FINAL REPORT
ASSESSING THE POTENTIAL FOR THE UPSTREAM CONTROL OF CONTAMINANTS PRESENT IN MATERIALS SPREAD TO LAND
SARA MONTEIRO, CAROL MILNER, CHRIS SINCLAIR, ALISTAIR BOXALL
DEFRA PROJECT: SP0578 FERA PROJECT: T6PU APRIL 2011
This report has been produced at The Food and Environment Research Agency on behalf of Defra EXECUTIVE SUMMARY
The UK produces over 100 million tonnes of biodegradable waste every year and a significant proportion of this is disposed of in landfills. In order to meet regulatory targets, the Government, local authorities and industry need to find alternatives to sending waste to landfill and, for some waste materials one option is to apply the material to soil.
The application of organic materials to soil not only provides nutrients and organic matter but also physical improvements. Each source of organic material has its own specific characteristic mix of organic matter, nutrients and structural improvers. When spread to land, organic materials recycle nutrients and organic matter back into the soil that otherwise would be destroyed by incineration or wasted in landfill. Requirements for the use of chemical fertilizer are also reduced by this practice. Inorganic materials can also improve the soil physical properties such as texture and porosity.
There is however potential disadvantages associated with land spreading of materials derived from wastes, primarily due to the potential contaminants they might contain. These disadvantages include threats to human and animal health, soil contamination and deterioration of soil structure, odour and visual nuisance, and pollution of water. There is therefore a need to gain an understanding of what contaminants are present in different waste types, the potential for these to enter the soil environment and, in instances where a contaminant poses a risk, approaches to control these risks.
Aim and scope
The overall aim of this project was therefore to identify contaminants and their sources in organic and inorganic materials spread to land in order to assist in the development of a strategy to help reduce the loadings of these contaminants at the source. This was addressed using a number of specific objectives:
To identify contaminants, and their sources, in organic and inorganic materials spread onto land; To quantify the relative contribution of total load that these sources represent in each material; To identify the relative importance of different waste materials in terms of inputs of contaminants to land; To identify approaches to reduce the loading at the source; To review relevant legislation and voluntary/advisory initiatives; and, To suggest best options for reducing inputs.
This study focused on a range of materials, namely: Sewage sludge Septic tank sludge
The Food and Environment Research Agency ii Livestock manure Biowaste Compost Digestate Industrial wastes: Pulp and paper industry sludge Waste wood, bark and other plant material Dredgings from inland waters Blood and gut contents from abattoir Textile waste Tannery and leather waste Waste from food and drinks preparation Waste from chemical and pharmaceutical manufacture Decarbonation sludge (predominantly inorganic) Sludge from the production of drinking water (predominantly inorganic) Waste lime and lime sludge (predominantly inorganic) Waste gypsum (predominantly inorganic)
Results and conclusions
Waste materials can be contaminated with a range of contaminants including potentially toxic elements (PTEs; Cu, Zn, Ni, Pb, Hg, Cd, Cr, As), organics (PCDDs, PCDFs, PAHs, PCBs, veterinary medicines, pesticides, pharmaceuticals, personal care products, endocrine disrupting substances) and animal and plant pathogens. These contaminants arise from a plethora of sources including households, highway runoff, industrial processes and combustion processes. The data on the occurrence of these contaminants varies depending on the waste type, with some materials having very limited data and some (most notably sewage sludge) having a significant amount of information on contaminant levels.
In order to assess the relative importance of different waste types as a source for soil contamination by a particular contaminant type, where possible, data on levels of contamination were combined with information on the application rates for the different waste types. This analysis demonstrated that for metals sewage sludge, compost, drinking water treatment sludge and meat processing liquids are the most important sources. For organics sewage sludge, dredgings, compost, abattoir waste and food and drink waste are important. For many contaminants, it was not possible to quantify the inputs from different waste materials so a more qualitative assessment was done. The results are shown in Table ES1.
The Food and Environment Research Agency iii Table ES1. Summary of the input of contaminants following the application of different wastes Contaminants Material Bulk industrial and Human Veterinary Biocides PTEs POPs Pesticides Pathogens domestic chemicals pharmaceuticals medicines and PCPs Sewage sludge ++ ++ + + ++ NR ++ unlikely Septic tank sludge ++ + + + ++ NR ++ ++ (if untreated) Livestock manures + + + + NR ++ NR ++ (if untreated) Compost + + + + NR NR NR + (low) Digestate + + + + NR NR NR + (low) Pulp and paper industry sludge + + + NR NR NR + unlikely Waste wood, bark and other + + + + NR NR + + (low) plant material Dredgings ++ ++ ++ + + + + + (low) Abattoir waste + + + + NR + NR + (medium) Textile waste + + + + NR NR + unlikely Tannery and leather sludge + + + + NR NR + unlikely Waste from food and drinks + + + NR NR NR NR + (low) preparation Waste from chemical and + + + NR + + + unlikely pharmaceutical manufacture Waste lime and lime sludge + + + NR NR NR NR unlikely Waste gypsum + + + NR NR NR NR unlikely Decarbonation sludge + + + NR NR NR NR + (low) Drinking water preparation + + + NR NR NR NR possible sludge NR – not relevant + relevant ++ one of the major sources
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A systematic approach was used to determine potential management options for different contaminant types. This considered regulatory approaches, control options at source as well as treatment options during the waste lifecycle. A number of options were highlighted including:
1. Sort and separate waste streams to reduce cross contamination of wastes. 2. Substitute persistent compounds, where alternative chemicals, that are less persistent, are currently available. 3. Use best available techniques in production processes 4. Restrict use of PTEs in animal feed by increasing the bioavailability of copper and zinc used, so that less is required. 5. Compost or thermophilic anaerobic digest to reduce some pathogens. 6. Consider the use of legislation to enforce these strategies. 7. Educate the public in the ultimate fate of waste materials and the need to control contaminant inputs.
Due to a lack of information in many areas covered in the report, it was not possible to produce definitive answers on the risks of different waste materials to the functioning of land and on how best to manage these. To address this, we therefore suggest that work in the future focuses on the following areas:
Consideration of a wider range of contaminant types; Consideration of a wider range of waste materials; Development of risk-based prioritisation schemes to identify contaminants of most concern; Development of a better understanding on the amounts of wastes materials applied to land; Establish the risks to the functioning of land; Study the benefits of different waste types in soil as well as the broader costs of waste material treatments and transport distances; Integrate waste disposal into risk assessment schemes for synthetic substances; Perform a social study on public awareness of waste and where it goes, followed by educational outreach about waste; Promote Green Chemistry for improving processes; and Assess waste mixtures and the best co-digestion practices.
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TABLE OF CONTENTS
1. INTRODUCTION...... 1 1.1. Waste in the UK ...... 2 1.2. Waste Strategy ...... 3 1.3. Landspreading ...... 4 1.4. Mechanisms for limiting contamination ...... 6 1.5. Aim and objectives ...... 6 2. APPROACH ...... 8 2.1. Data used ...... 8 2.2. Definition of terms ...... 8 2.3. Materials considered ...... 11 2.4. Contaminants ...... 12 2.4.1. Potentially toxic elements ...... 12 2.4.2. Organic compounds ...... 13 2.4.3. Pathogens ...... 24 3. CONCENTRATIONS OF CONTAMINANTS IN MATERIALS SPREAD ONTO LAND ...... 25 3.1. Sewage sludge ...... 25 3.1.1. Introduction ...... 25 3.1.2. Treatment ...... 25 3.1.3. Contaminants ...... 26 3.1.4. Legislation ...... 31 3.2. Septic tank sludge ...... 34 3.2.1. Introduction ...... 34 3.2.2. Contaminants ...... 34 3.3. Livestock manure ...... 35 3.3.1. Introduction ...... 35 3.3.2. Treatment ...... 35 3.3.3. Contaminants ...... 36 3.3.4. Legislation ...... 40 3.4. Biowaste ...... 43 3.4.1. Introduction ...... 43 3.4.2. Current techniques for dealing with biowaste ...... 43
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3.4.3. Treatment - Composting ...... 44 3.4.4. Treatment – Anaerobic digestion ...... 64 3.4.5. Legislation ...... 66 3.5. Industrial waste materials ...... 69 3.5.1. Introduction ...... 69 3.5.2. Legislation ...... 70 3.5.3. Pulp and paper industry Sludge ...... 71 3.5.4. Waste wood, bark or other plant material ...... 75 3.5.5. Dredgings from inland waters ...... 79 3.5.6. Abattoir wastes ...... 82 3.5.7. Textile industry waste...... 87 3.5.8. Tannery and leather waste ...... 90 3.5.9. Waste from food and drinks preparation ...... 92 3.5.10. Waste from chemical and pharmaceutical manufacture ...... 94 3.6. Inorganic wastes ...... 96 3.6.1. Sludge from the production of drinking water ...... 97 3.6.2. Decarbonation sludge ...... 99 3.6.3. Waste lime and lime sludge ...... 100 3.6.4. Waste gypsum ...... 101 4. CONTAMINANT LOADINGS FROM APPLICATION OF MATERIALS ONTO LAND...... 104 4.1. Introduction ...... 104 4.2. Contaminants ...... 106 4.2.1. PTEs...... 106 4.2.2. Organic compounds ...... 112 4.2.3. Pathogens ...... 116 5. IDENTIFICATION OF POSSIBLE STRATEGIES TO REDUCE CONTAMINATION OF MATERIALS SPREAD TO LAND ...... 122 5.1. Introduction and approach used ...... 122 5.2. Sewage Sludge ...... 124 5.2.1. Potentially toxic elements ...... 124 5.2.2. Organic compounds ...... 129 5.2.3. Pathogens ...... 133
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5.2.4. Summary ...... 133 5.3. Livestock manure ...... 137 5.3.1. Potentially toxic elements ...... 137 5.3.2. Organic compounds ...... 139 5.3.3. Pathogens ...... 140 5.3.4. Summary ...... 142 5.4. Municipal solid waste ...... 144 5.4.1. Potentially toxic elements ...... 144 5.4.2. Organic Compounds ...... 146 5.4.3. Pathogens ...... 146 5.4.4. Summary ...... 147 5.5. Paper and pulp waste ...... 150 5.5.1. PTEs...... 150 5.5.2. Organic Contaminants ...... 152 5.5.3. Pathogens ...... 153 5.5.4. Summary ...... 153 5.6. Waste wood, bark and other plant waste ...... 156 5.6.1. PTEs...... 157 5.6.2. Organic Compounds ...... 158 5.6.3. Pathogens ...... 159 5.6.4. Summary ...... 159 5.7. Dredgings from inland waters ...... 161 5.7.1. PTEs...... 162 5.7.2. Organic Contaminants ...... 162 5.7.3. Pathogens ...... 163 5.7.4. Summary ...... 163 5.8. Abattoir waste ...... 167 5.8.1. PTEs...... 167 5.8.2. Organic Contaminants ...... 168 5.8.3. Pathogens ...... 168 5.8.4. Summary ...... 169 5.9. Textile industry waste ...... 172
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5.9.1. PTEs...... 172 5.9.2. Organic Contaminants ...... 173 5.9.3. Pathogens ...... 176 5.9.4. Summary ...... 176 5.10. Tannery and leather waste ...... 179 5.10.1. PTEs...... 179 5.10.2. Organic Compounds ...... 180 5.10.3. Pathogens ...... 183 5.10.4. Summary ...... 183 5.11. Waste from food and drinks preparation ...... 185 5.11.1. PTEs...... 186 5.11.2. Organic Contaminants ...... 186 5.11.3. Pathogens ...... 187 5.11.4. Summary ...... 188 5.12. Waste from chemical and pharmaceutical manufacture ...... 191 5.12.1. PTEs...... 192 5.12.2. Organic Compounds ...... 192 5.12.3. Pathogens ...... 194 5.12.4. Summary ...... 194 5.13. Summary of Information ...... 197 5.14. Interpretation of information ...... 204 5.15. Significance ...... 206 5.16. The future ...... 207 5.16.1. Waste Management ...... 207 5.16.2. Agriculture ...... 207 5.16.3. Energy Production ...... 207 5.16.4. Population behaviour ...... 207 5.17. Discussion ...... 207 6. SUGGESTIONS FOR FURTHER STUDY ...... 209 7. REFERENCE LIST ...... 211 APPENDIX A ...... 230 APPENDIX B ...... 233
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APPENDIX C ...... 245 APPENDIX E ...... 249 APPENDIX F ...... 254
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LIST OF TABLES
Table 1.1 Recycling of selected metals as a percentage of consumption (Defra, 2007c) ...... 4 Table 1.2 Problems associated with and ultimate fate of different contaminants in waste materials (Amlinger et al., 2004a)...... 5 Table 2.1 Annual heavy metal inputs to agricultural land in England and Wales in 2004 (mg/kg)(ADAS, Imperial College, JBA Consulting, 2005) ...... 13 Table 2.2 Organic contaminants found in different material types ...... 14 Table 2.3 Volume of pharmaceutically active compounds sold in the UK (kg/year; data from EA, 2008b) ...... 19 Table 2.4 Major veterinary medicines in use in the UK (Boxall et al., 2004) ...... 21 Table 3.1 Examples of sewage sludge treatment processes (DoE, 1996a) ...... 26 Table 3.2 Concentrations of metals/elements in UK sewage sludge in mg/kg dry weight ...... 27 Table 3.3 Summary of range concentrations (minimum value, highest maximum and highest mean reported within the class) for organic contaminants detected in UK sewage sludge in mg/kg dry weight (unless otherwise stated; UKWIR, 1995; Wild and Jones, 1992; Wilson et al., 1997; Wild et al., 1993; Wang et al., 1995; Rogers et al., 1989; Nicholls et al., 2001; Bowen et al., 2003; McIntyre and Lester, 1982; McIntyre and Lester, 1984; Stevens et al., 2001; Stevens et al., 2003; Leschber, 2006; Sewart et al., 1995; Jones and Northcott, 2000) ...... 29 Table 3.4 Legislation/ voluntary initiatives on the use of sludge ...... 32 Table 3.5 Contaminants limits available in legislation, policy or voluntary initiatives for sewage sludge applied to land in Europe and UK (in mg/kg dry matter, unless otherwise stated) ... 33 Table 3.6 Examples of treatments for farm manures (Hickman et al., 2009) ...... 36 Table 3.7 Typical concentrations of PTEs in manures (ADAS, 2009) ...... 37 Table 3.8 Concentrations of veterinary medicines found in animal manures (Boxall et al., 2004) 38 Table 3.9 Sulfonamide and trimethoprim residues in manure samples in mg kg -1 fresh weight (Haller et al., 2002) ...... 39 Table 3.10 Pathogens found in animal manure (Nicholson et al., 2000) ...... 40 Table 3.11 Legislation/ voluntary initiatives on the use of livestock ...... 41 Table 3.12 Previous (SI 2000/2481) and current (EC, 2003) maximum permitted levels of zinc and copper in livestock feeds (mg/kg complete feed) ...... 42 Table 3.13 Production of mushrooms and spent mushroom compost in 1999 and 2003 (DETR, 2000; Defra, 2005b) ...... 46 Table 3.14 Concentrations of PTEs in green/food compost ...... 47 Table 3.15 Concentrations of PTEs in green compost ...... 49 Table 3.16 Concentrations of PTEs in municipal solid waste composts ...... 51 Table 3.17 Concentrations of PTEs in mechanical biological treatment compost-like outputs ...... 52 Table 3.18 Concentrations of PTEs in mechanical heat treatment compost-like outputs (CalRecovery, 2007) ...... 52 Table 3.19 Average metal content in potential MHT CLO and non-segregated municipal solid waste compost...... 53 Table 3.20 Heavy metal concentrations in compost of mixtures ...... 54
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Table 3.21 Concentrations of further potential toxic elements in compost ...... 55 Table 3.22 Concentrations of PAHs in composts in μg/kg dry weight (unless otherwise stated) .. 57 Table 3.23 Concentrations of PCBs in composts in μg/kg dry weight (unless otherwise stated) ... 58 Table 3.24 Concentrations of PCDD/Fs in composts in ng [I-TEQ]/kg dry weight (unless otherwise stated) ...... 59 Table 3.25 Use of pesticides on mushrooms grown in Great Britain in 2003 (CSL, 2004) ...... 63 Table 3.26 Concentrations of PTEs in digestate from the UK (ADAS, 2009) ...... 65 Table 3.27 Concentrations of organic compounds in Swiss digestates in µg/kg dry weight (dw) unless otherwise stated (Kupper et al., 2006) ...... 65 Table 3.28 Legislation/ voluntary initiatives on the use of compost/digestate ...... 67 Table 3.29 Limits for contaminants for compost (class 1 and 2), digestate and stabilised biowaste ...... 68 Table 3.30 Assessment of likely concentrations of organic contaminants in a range of wastes (Aitken et al., 2002) ...... 70 Table 3.31 Legislation/ voluntary initiatives on the use of industrial wastes on land ...... 71 Table 3.32 Concentrations of metals in paper sludge, de-inked paper pulp and waste paper (mg/kg dry solids; mean (min;max)) ...... 73 Table 3.33 Organic contaminants concentrations in the pulp and paper industry sludge (in mg/kg dry weight; Gendebien et al., 2001)...... 74 Table 3.34 Concentration of PTEs in waste wood, bark and other plant material (mg/kg dw; Davis and Rudd, 1999) ...... 76 Table 3.35 Concentrations of organic compounds detected in waste wood, bark and other plant material (Gendebien et al., 2001) ...... 76 Table 3.36. Plant pathogens and nematodes, hosts and common name of diseases caused, or of nematodes (Noble and Roberts, 2004) ...... 78 Table 3.37 PTEs /elements and other inorganic chemicals reported in dredgings (in mg/kg dw) . 80 Table 3.38 Summary of range concentrations (minimum value, highest maximum and highest mean reported within the class) for organic contaminants detected in sediments in µg/kg dry weight (unless otherwise stated)(Allchin et al., 1999; Eljarrat and Barcelo, 2003; Long et al., 1998; Daniels et al., 2000; Buser et al ., 1998; Braga et al., 2005; Ternes et al., 2002; López de Alda et al., 2002; Ferrer et al., 2004; Davis and Rudd, 1999; Metre and Mahler, 2005; Micić and Hofmann, 2009; Eljarrat and Barcelo, 2004) ...... 81 Table 3.39 Metal concentrations in abattoir wastes in the UK (mean (min; max) in mg/kg) ...... 85 Table 3.40 Organic contaminants in abattoir wastes (in mg/kg dry weight; Gendebien et al., 2001) ...... 86 Table 3.41 Metal concentrations in textile waste in mg/kg dw...... 88 Table 3.42 Organic compounds levels in textile waste in mg/kg dw (Gendebien et al 2001) ...... 90 Table 3.43 Concentrations for PTEs in tannery sludge (mg/kg dry weight) ...... 91 Table 3.44 Concentration of PTEs in the animal food production industry ...... 96 Table 3.45 Concentration of PTEs in the food and drinks production industry ...... 97 Table 3.46 Concentrations of organic contaminants detected in food and drink industry sludge (Gendebien et al., 2001) ...... 94 Table 3.47 Concentrations of PTEs in wastes from the chemical and pharmaceutical industry (Gendebien et al., 2001) ...... 95
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Table 3.48 Concentrations of PTEs in sludge from waterworks in mg/kg dry weight (WRc, 2009) 98 Table 3.49 Concentration of PTEs in decarbonation sludge in mg/kg dry weight (Gendebien et al., 2001) ...... 100 Table 3.50 Concentration of PTEs in waste lime and lime sludge (mg/kg dry weight) ...... 101 Table 3.51 Concentration of PTEs in waste gypsum from plasterboard (mg/kg dry weight) ...... 103 Table 4.1 Application rates of materials to land used to calculate input of contaminants ...... 105 Table 4.2 Heavy metal summary input following the application of different materials to land. Comparison with sewage sludge inputs...... 112 Table 4.3 Qualitative assessment of pathogens levels in materials applied to land ...... 116 Table 4.4 Summary of the input of contaminants following the application of different wastes 112 Table 5.1 Judgment for practicality and effectiveness ...... 123 Table 5.2 Domestic sources of metals/elements in wastewater (IC Consultants, 2001) ...... 125 Table 5.3 Domestic sources of potentially toxic elements in urban wastewater (modified from Lester, 1987 and WRc, 1994 as cited in IC Consultants, 2001) ...... 126 Table 5.4 Industrial sources of metals/elements in wastewater (IC Consultants, 2001) ...... 127 Table 5.5 Sources of organic contaminants in sewage sludge ...... 129 Table 5.6 Description of common additives in a range of personal care products (Xia et al., 2005) ...... 130 Table 5.7 Upstream control measures for reducing contaminants in sewage sludge ...... 135 Table 5.8 Upstream control measures for reducing contaminants in livestock manure ...... 143 Table 5.9 Upstream control measures for reducing contaminants in municipal solid waste ...... 148 Table 5.10 Upstream control measures for reducing contaminants in paper and pulp waste ..... 154 Table 5.11 Result of risk assessment of treated waste wood (WRAP, 2005) ...... 157 Table 5.12 Upstream control measures for reducing contaminants in wood, bark and other plant waste ...... 160 Table 5.13 Upstream control measures for contaminants in dredgings from inland waters ...... 164 Table 5.14 Upstream control measures for reducing contaminants in abattoir waste ...... 170 Table 5.15 BAT for the substitution of hazardous chemicals in the textile industry (IPPC, 2003a) ...... 174 Table 5.16 BAT for the selection of incoming fibre materials (IPPC, 2003a) ...... 175 Table 5.17 Chemical and Physical treatments of textile waste (Robinson et al., 2001)...... 176 Table 5.18 Upstream control measures for reducing contaminants in textile industry waste. .... 177 Table 5.19 Level of chemicals used to process salted bovine hides (IPPC, 2003b) ...... 181 Table 5.20 Substances currently used and BATs substitutes (IPPC, 2003b) ...... 182 Table 5.21 Upstream control measures for reducing contaminants in tannery and leather waste...... 184 Table 5.22 Upstream control measures for reducing contaminants in the food and drink industry waste...... 189 Table 5.23 Upstream control measures for reducing contaminants in the chemical and pharmaceutical industry waste...... 195 Table 5.24 Summary table for the most effective measure to reduce PTEs contamination according to highest input material...... 198 Table 5.25 Summary table for the most effective measures to reduce organic compounds contamination according to input materials...... 200
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Table 5.26 Summary table for the most effective measures to reduce pathogen contamination according to input materials...... 203
Appendices Table A - 1 Prioritisation assessment for veterinary compounds that have the potential to enter the environment (Boxall et al., 2003) ...... 230 Table A - 2 Concentrations reported for organic contaminants in sewage sludge in the UK ...... 233 Table A - 3 Plant toxins that may occur in green compost ...... 246 Table A - 4 Concentration ranges of compounds detected in bed sediments ...... 249
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LIST OF FIGURES
Figure 1.1. Estimated total annual waste arising by sector: 2004 (Defra 2007a)...... 2 Figure 1.2 Summary of the management of waste in 2004 (Defra 2007a)...... 3 Figure 1.3 The “Waste hierarchy” (EU, 2008; Defra, 2007b) ...... 3 Figure 4.1 Total metal input following the application of different materials ...... 106 Figure 4.2 Loading in g/ha following application of different materials to soils - Cadmium ...... 107 Figure 4.3 Loading in g/ha following application of different materials to soils - Chromium ...... 108 Figure 4.4 Loading in g/ha following application of different materials to soils - Copper ...... 108 Figure 4.5 Loading in g/ha following application of different materials to soils - Nickel ...... 109 Figure 4.6 Loading in g/ha following application of different materials to soils - Lead ...... 109 Figure 4.7 Loading in g/ha following application of different materials to soils - Zinc ...... 110 Figure 4.8 Loading in g/ha following application of different materials to soils - Mercury ...... 110 Figure 4.9 PTEs loading in g/ha following application of dredgings or sewage sludge to soils ... 111 Figure 4.10 PAH loading in g/ha following application of materials to soils ...... 113 Figure 4.11 PAH loading in g/ha following application of materials to soils ...... 114 Figure 4.12 PCBs loading in mg/ha following application of different materials to soils ...... 115 Figure 4.13 PCB loading in mg/ha following application of materials to soils ...... 115 Figure 5.1 Sewage sludge waste stream ...... 124 Figure 5.2 Livestock manure waste stream ...... 137 Figure 5.3 Municipal solid waste stream ...... 144 Figure 5.4 Paper mills waste stream ...... 150 Figure 5.5 Waste wood, bark and other plant waste ...... 156 Figure 5.6 Dredgings waste stream ...... 161 Figure 5.7 Abattoir waste stream ...... 167 Figure 5.8 Textile industry waste stream ...... 172 Figure 5.9 Tannery and leather waste stream ...... 179 Figure 5.10 Waste from food and drinks preparation stream ...... 185 Figure 5.11 Chemical and pharmaceutical manufacture waste stream ...... 191
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ABBREVIATIONS
BAT – Best Available Technique G/FC- Green/Food Compost CSF- Chemicals Stakeholder Forum EC – European Commission ERA – Environmental Risk Assessment EU – European Union EWC - European Waste Catalogue GC – Green Compost MBT – Mechanical Biological Treatment MHT – mechanical Heat treatment MSW – Municipal Solid waste MSWC- Municipal Solid waste compost PRTRs - Pollutant Release and Transfer Registers PVC - polyvinyl chloride REACh - Registration Evaluation and Authorisation of Chemicals STP – Sewage Treatment Plant USA – United States of America WFD – Water Framework directive
Potentially toxic elements: As - arsenic Cd – cadmium Cr – chromium Cu – copper Ni – nickel Pb – lead Hg – mercury Zn - zinc
Organic contaminants: AOX – adsorbable organic halides BBP - butyl benzyl phthalate BFRs- brominated flame retardants CBs – chlorobenzenes DBP - di-n-butyl phthalate DEHP - di(2-ethylhexyl)phthalate DIDP - diisodecyl phthalate DINP - diidononyl phthalate EDCs – endocrine disrupting chemicals HCBD - hexachlorobutadiene
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LAS – linear alkylbenzene sullfonates MBTE - methyl tertiary butyl ether NPE – nonylphenol ethoxylate NPs - nonylphenols PAHs – polycyclic aromatic hydrocarbons PBDEs – polybrominated diphenylethers PCBs – polychlorinated biphenyls PCDD/Fs – polychlorinated dibenzo dioxins/furans PCNs – polychlorinated naphthalenes PCP – pentachlorophenol PCPs – Personal Care Products POPs – Persistent Organic Pollutants PTEs- Potentially Toxic Elements TBBP-A - tetrabromobiphenol
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1. INTRODUCTION
The UK produces over 100 million tonnes of biodegradable waste every year and a significant proportion of this is disposed of in landfills. In order to meet regulatory targets, the Government, local authorities and industry need to find alternatives to sending waste to landfill and also explore opportunities to produce high quality materials from biodegradable wastes (EA, 2008a).
Once identified as waste, material falls under European and national legislation. The Waste Framework Directive 2008 regulates disposal of waste in Europe and prioritises prevention of waste and the reuse and recovery of waste (EU, 2008). In the UK, the Waste Framework Directive has been implemented by the following national legislation: the Environmental Protection Act (1990), the Control of Pollution (amendment) Act ( SI 1991/1618), the Waste Management Licensing Regulations ( SI 1994/1056), and the Controlled Waste Regulations (SI 1991/1624)(Wasteonline, 2005). Disposal and management of waste is further regulated by the Directive on the Landfill of Waste (EU, 1999), Landfill (England and Wales) Regulations (2002), and the Directive on Waste Incineration (EU 2000a). The Landfill Directive sets standards for design, operation, and aftercare of landfills and restricts the contents. Hazardous wastes are particularly restricted and the Directive lays down requirements to reduce the amount of biodegradable wastes going to landfill over certain time periods, e.g. the amount of biodegradable municipal waste being landfilled in 2020 must be reduced to 35% (by weight) of that in 1995. Moreover to increase the incentive to divert waste from landfill sites a landfill tax was introduced that charges for waste disposal to landfill (WRc, 2009).
Waste recovery by landspreading, when environmentally acceptable, is promoted by the legislative framework for waste management in the EU (EU, 2008) and in the UK. In the UK, it is estimated that the amount of wastes recycled to land is about 22 million tonnes dry solids per year. Farm wastes account for 94% of these wastes, with sewage sludge and other wastes accounting for 2% and 4%, respectively (Davis and Rudd, 1999).
A main requirement for the exemption for landspreading of controlled wastes is that an agricultural benefit or ecological improvement is achieved (EC, 2001). For conventional fertilizers such as livestock manures and sewage sludge, it has been proven that there is an agricultural benefit (ADAS, Rothamsted Research, WRc, 2007; Edmeades, 2003). However, this is not necessarily the case for other classes of wastes where there is insufficient information on the risks and benefits to land.
The range of names used for biodegradable wastes reflects a variety of uses, value, quality and impact on the environment. Among them sewage sludge, livestock manures, compost and digestate. Some are considered to be wastes, others products, depending on the circumstances (EA, 2009). Before application to land some of these wastes are treated and some are directly spread without further treatment. To avoid confusion, within this report the term “ material ” will be used for all wastes or products that can be spread to agricultural land.
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One area that needs consideration relates to the potential risks of chemical and biological contaminants that might arise from different materials applied to land (Davis and Rudd, 1999). Therefore, an inventory of contaminants and their sources in materials applied to land is performed within this report in order to develop a strategy to reduce loadings of these contaminants at the source.
1.1. Waste in the UK
The Environmental Services Association states that the total amount of waste produced in the UK is 434 million tonnes each year (ESA, 2009) although it does not specify the year or source of the data. Figure 1.1 shows the proportion of wastes produced by sector in the UK in 2004, and gives the total annual waste at 335 million tonnes (Defra 2007a). This figure, however, does not include manure and straw from the agricultural sector.
Figure 1.1. Estimated total annual waste arising by sector: 2004 (Defra 2007a).
The approaches used for the management of the waste produced in 2004 are shown in Figure 1.2, illustrating that in 2004 over 66% of waste was disposed of into or onto land or into water and only 32% was recycled, i.e. reprocessed into products, materials or substances whether for the original or other purposes.
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Figure 1.2 Summary of the management of waste in 2004 (Defra 2007a).
1.2. Waste Strategy
The European Union Directive 2008/98/EC (EU, 2008) defines a priority order in waste prevention and management legislation and policy as a “waste hierarchy” (Figure 1.3). Reduction of waste is the most preferable route toward sustainability, followed by reuse of waste. Recycling and composting have preference over energy recovery, and disposal is the least desirable option. Management of waste should follow this order of priorities. To move towards sustainable waste management, national waste strategies have also been produced for England and these were published in the Waste Strategy for England 2007 (Defra, 2007b).
Figure 1.3 The “Waste hierarchy” (EU, 2008; Defra, 2007b)
A number of directives encourage recycling of specific materials and these include the Directive on Batteries and Accumulators (EC, 1991a), the Packaging and Packaging Waste Directive (EU, 1994), and the Waste Electrical and Electronic Equipment (WEEE) Directive (EU, 2003). The Household Waste Recycling Act (2003) encourages domestic recycling by requiring all English waste collection authorities to collect a minimum of two types of recyclable waste. This service is already being provided for 90% of English households (Defra
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2009). Wastes such as glass, paper, plastic, and aluminium can be recycled into similar products.
Table 1.1 shows the percentage of consumption of selected materials recycled in 2003 (Defra 2007c).
Table 1.1 Recycling of selected metals as a percentage of consumption (Defra, 2007c) Ferrous metals Lead Paper & board Glass containers Aluminium packaging Plastic 33 60 38 35 26 10
Waste management options for biodegradable waste include, in addition to prevention at source, collection (separated or mixed waste), anaerobic digestion and/or composting, incineration, and landfilling. The environmental and economic benefits of different treatment methods depend significantly on local conditions such as population density, infrastructure and climate as well as on markets for associated products (energy and composts) (CEC, 2008).
Other waste types can be recycled or recovered in other ways. For instance, gypsum can be used to make plasterboard, quarry waste can be used for construction materials, and some wastes can be spread to land to improve soil properties.
The European Waste Catalogue 2002 (EWC) includes a list of waste types established by the European Commission (EC, 2000a), under which all wastes should be classified. It is brought in force by List of Wastes (England) and List of Wastes (Wales) Regulations 2005. The List of Waste codes are split into 20 chapters (2 digit code) based on the source from which the waste arises and then further split in to subchapters (up to 6 digit codes), but there is no specification on which wastes are allowed to be spread on land.
In a report for Defra (WRc, 2009) a large variability was observed across most parameters within the same waste code, since it includes many waste streams with different characteristics that should be evaluated in greater detail. Therefore, in this report the waste codes have not been used.
1.3. Landspreading
In the Waste Management Licensing (England and Wales) Regulations (2005), in paragraph 7 of Schedule 3, all materials allowed to be spread to agricultural land where “ such treatments results in benefit to agriculture or ecological improvement ” are presented (SI 2005/1728). To claim agricultural benefit it must be proved that the material will improve the soil for growing crops or grazing (WRc, 2009). The definition used by the Environment Agency for agricultural benefit/ecological improvement is that given by Davis and Rudd (1999) and may be considered in terms of: Crop yield and quality; Soil chemical properties; Soil physical properties; Soil biological properties; and The Food and Environment Research Agency 4
Soil water content.
Before application to land, some of these materials are treated and some are directly spread without further treatment. Composting is the most common biological treatment option and is the best suited method for the treatment of green waste and wood material (CEC, 2008). Anaerobic digestion is best suited for treating wet biodegradable wastes, including fat. It produces a gas mixture mainly composed of methane (50 to 75%) and carbon dioxide. The residue from the process, the digestate can be composted and used for similar purpose as compost.
The application of organic materials to soil not only provides nutrients and organic matter but also physical improvements. Each source of organic material has its own specific characteristic mix of organic matter, nutrients and structural improvers. When spread to land, organic materials recycle nutrients and organic matter back into the soil that otherwise would be destroyed by incineration or wasted in landfill. Requirements for the use of chemical fertilizer are also reduced by this practice (Amlinger et al., 2004a). Inorganic materials are used to improve the soils physical properties such as texture, porosity and alkalinity and may also provide some nutrients (Davis and Rudd, 1999).
There are however potential disadvantages associated with landspreading materials derived from wastes, primarily due to the potential contaminants they might contain. These disadvantages include threats to human and animal health, soil contamination and deterioration of structure, odour and visual nuisance, and pollution of water (Davis and Rudd, 1999; Gendebien et al., 2001). Table 1.2 summarises the threats from different contaminant classes and their fate once applied to soil. Excessive nutrient overloading, heavy metal contaminants, organic contaminants, and pathogens are the source of these threats (Amlinger et al., 2004a).
Table 1.2 Problems associated with and ultimate fate of different contaminants in waste materials (Amlinger et al., 2004a). Fate Threat in soil Degradation in soil Transference Excess carbon can temporarily immobilize nitrogen. Soil will rebalance with time, Leaching into water. Nutrients Excess nitrogen can contaminate although the time may be Uptake by plants. surface water. substantial Sorption on soil particles. Eutrophication. Impair mechanisms of microbe reproduction. Leaching into water. Accumulate in soil, do not Metals Accumulate in plants, animals and Uptake by plants. degrade. humans, causing health problems Sorption on soil particles. e.g. Mercury, chromium Bioaccumulation through plants and Some are persistent and animals to humans Leaching into water. accumulate, and others degrade Organic e.g. PCB and PAH. Uptake by plants. readily. Contaminants Toxic to plants and microbes so Sorption on soil particles. Degradation products can cause reduce soil functioning Volatilisation. more threats. e.g. antibiotics. Infection of plants, animals, and Spread by movement of soil, Pathogens humans ( e.g. Escherichia coli O157 Multiply in the right conditions. water, plants, animals, and and Salmonella) humans. The Food and Environment Research Agency 5
1.4. Mechanisms for limiting contamination
To protect soils, animals, humans and the environment the wastes spread on land need to be controlled. The Environment Agency regulates the use and disposal of wastes through the Environmental Permitting Regulations 2007 (WRc, 2009; EA, 2008a). Other legislation limits what and how much can be spread, where, how and when. For example: Any waste containing animal products including meat falls under the Animal By- products Regulation (EU, 2002). It may only be spread after being digested in an approved category 3 facility and may not be spread onto pasture land (WRc, 2009). Wood treated with copper chromium arsenate is not allowed to be composted for spreading onto land under the Control of Dangerous Substances Regulations (SI (2003/3274). The Sewage Sludge Directive (EC, 1986) regulates the use of sludge in agriculture to prevent harmful effects for soil, animals and humans. Waste can be treated to minimize harmful effects. Organic waste is stabilized by composting (aerobic digestion) or anaerobic digestion. These treatments may reduce levels of organic contaminants and pathogens. There are other possible treatments such as electro remediation for PTEs (Dach and Starmans, 2006; Petersen et al. 2007) and biological treatments such as using fungi to break down organic contaminants (Robinson et al., 2001).
It is better practice to prevent the contaminants from entering the production process and waste stream in the first place. A range of mechanisms exist to achieve this including: Environmental Risk Assessment (ERA) on chemicals can generate information about which chemicals are most hazardous and be used to manage their use; Green Chemistry research is developing new alternatives to hazardous substances and processes; and the REACh (Registration Evaluation and Authorisation of Chemicals) Regulations are beginning to provide information on which chemicals are the most hazardous. All this information can be used to improve production processes and reduce contamination risks. Recognition can be gained for using Best Available Techniques Not Entailing Excessive Cost (BATNEEC, from here on in called “BAT”) (Thompson et al. 2001). The development of standards for waste may also provide a mechanism to encourage producers of waste materials to minimise the level of contamination. The Publicly Available Specification 100, “PAS 100” (BSI, 2005) for composted materials is a non-statutory standard that demonstrates good practice and in composting organic material. The PAS 100 standard enables users of compost to be confident in its quality. A similar standard or award for all producers of organic waste to a recognised safe standard for land application would provide incentivise to use best practices. The choice of individuals can influence contamination. Public awareness of environmental issues enables educated choices that can drive changes in industry and practices.
1.5. Aim and objectives
The overall aim of this project is to identify contaminants and their sources in organic and inorganic materials spread to land in order to develop a strategy to help in reducing the loadings of these contaminants at the source.
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This was addressed using a number of specific objectives: To identify contaminants, and their sources, in organic and inorganic materials spread onto land; To quantify the relative contribution of total load that these sources represent in each material; To identify the relative importance of different waste materials in terms of inputs of contaminants to land; To identify approaches to reduce the loading at the source; To review relevant legislation and voluntary/advisory initiatives; and, To suggest best options for reducing inputs.
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2. APPROACH
2.1. Data used
The study was desk-based and utilised a range of information including:
Defra funded research European Commission reports Environment Agency reports Industry reports Confidential data Scientific literature
In addition, a workshop was held at Fera at Sand Hutton in October 2009 to present the interim results of the study and to gain feedback from a range of stakeholders. This report therefore also reflects some of the discussions at this workshop.
2.2. Definition of terms
Due to the fact that some wastes are landspread untreated and others treated (e.g. compost) within this report the term “ material ” is applied for all wastes/products applied to land. Below we define some material types and terms discussed in the report.
Waste
“biowaste ” is defined in the European Union Directive 2008/98/EC as “ biodegradable garden and park waste, food and kitchen waste from households, restaurants, caterers and retail premises and comparable waste from food processing plants .”
“by-product ” is defined in article 5 of the European Union Directive 2008/98/EC as a “substance or object, resulting from a production process, the primary aim of which is not the production of that item, may be regarded as not being waste referred to in point (1) of Article 3 but as being a by-product only if the following conditions are met: Further use of the substance or object is certain; The substance or object can be used directly without any further processing other than normal industrial practice; The substance or object is produced as an integral part of a production process; Further use is lawful, i.e. the substance or object fulfils all relevant product, environmental and heath protection requirements for the specific use and will not lead to overall adverse environmental or human health impacts”
“collection ” is defined in the European Union Directive 2008/98/EC as “ the gathering of waste, including the preliminary sorting and preliminary storage of waste for the purposes of transport to a waste treatment facility ”.
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“disposal ” is defined in the European Union Directive 2008/98/EC as “any operation which is not recovery even where the operation has as a secondary consequence the reclamation of substances or energy. ”
“end-of-waste status ” in article 6 of the European Union Directive 2008/98/EC “is applied to certain specified waste shall cease to be waste within the meaning of point (1) of Article 3 when it has undergone a recovery, including recycling, operation and complies with specific criteria to be developed in accordance with the following conditions: the substance or object is commonly used for specific purposes; a market or demand exists for such substance or object; the substance or object fulfils the technical requirements for the specific purposes and meets the existing legislation and standards applicable to products; and the use of the substance or object will not lead to overall adverse environmental or human health impacts”.
“green waste ” is defined within this report as source separated waste composed of garden or park waste, such as grass or flower cuttings, bush and tree cuttings, leaves, etc.
“recovery ” is defined in the European Union Directive 2008/98/EC as “any operation the principal result of which is waste serving a useful purpose by replacing other materials which would otherwise have been used to fulfil a particular function, or waste being prepared to fulfil that function, in the plant or in the wider economy ”.
“recycling ” is defined in the European Union Directive 2008/98/EC as “ any recovery operation by which waste materials are reprocessed into products, materials or substances whether for the original or other purposes. It includes the reprocessing of organic material but does not include energy recovery and the reprocessing into materials that are to be used as fuels or for backfilling operations” .
“re-use ” is defined in the European Union Directive 2008/98/EC as “ any operation by which products or components that are not waste are used again for the same purpose for which they were conceived” .
“separate collection ” is defined in the European Union Directive 2008/98/EC as “ the collection where a waste stream is kept separately by type and nature so as to facilitate treatment ”.
“treatment ” is defined in the European Union Directive 2008/98/EC as “ recovery or disposal operations, including preparation prior to recovery or disposal ”.
“waste ” is defined in the European Union Directive 2008/98/EC as “ any substance or object which the holder discards or intends or is required to discard ”. Anaerobic digestate
“anaerobic digestion ” is defined in the PAS for Anaerobic Digestion Materials (BSI, 2008) as the “process of controlled decomposition of biodegradable materials under managed The Food and Environment Research Agency 9
conditions where free oxygen is absent, at temperatures suitable for naturally occurring mesophilic or thermophilic anaerobic and facultative bacteria species, that convert the inputs to a methane rich biogas and whole digestate”
“separated fibre ” is defined in the PAS for Anaerobic Digestion Materials (BSI, 2008) as the “fibrous fraction of material derived by separating the coarse fibres from whole digestate” .
“separated liquor ” is defined in the PAS for Anaerobic Digestion Materials (BSI, 2008) as the “liquid fraction of material remaining after separating coarse fibrous particles from whole digestate” .
“whole digestate ” is defined in the PAS for Anaerobic Digestion Materials (BSI, 2008) as the “material resulting from a digestion process and that has undergone a post-digestion separation step to deriver separated liquor and separated fibre” .
Compost
“compost ” is defined in the Publicly Available Specification (PAS) for Composted Materials (BSI, 2005) as a “solid particulate material that is the result of composting, that has been sanitized and stabilized and that confers beneficial effects when added to soil, used as a component of a growing medium, or is used in another way in conjunction with plants”
“composting ” is defined in the Specification for Composted Materials (BSI, 2005) as “the process of controlled biological decomposition of biodegradable materials under managed conditions that are predominantly aerobic and that allow the development of thermophilic temperatures as a result of biologically produced heat”.
“green compost” is defined within this report as green waste compost derived from source- separated collection schemes.
“green/food compost” is defined within this report as compost derived from separately collected household waste, including kitchen waste.
“input material ” is defined in the Specification for Composted Materials (BSI, 2005) as the “biodegradable material going into a composting process”.
“mixed municipal solid waste compost” is defined within this report as compost derived from non-segregated municipal solid waste and represents the organic waste fraction in municipal waste.
“mechanical-biological treatment compost-like output” ” is defined within this report as compost derived from the mechanical-biological treatment of non-segregated municipal solid waste. “mechanical heat treatment compost-like output” is defined within this report as compost derived from the mechanical heat treatment of non-segregated municipal solid waste.
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“spent mushroom compost” is defined within this report as compost derived from the mushroom industry.
Sewage sludge
“domestic waste water ” is defined in Directive 91/271/EEC (EC, 1991b) as “waste water from residential settlements and services which originates predominantly from the human metabolism and from household activities”
"septic tank sludge " is defined in the Sludge (Use in Agriculture) Regulations 1989 (SI 1989/1263) as “the residual sludge from septic tanks and other similar installations for the treatment of sewage”
“sludge ” is defined in the Sludge (Use in Agriculture) Regulations 1989 (SI 1989/1263) as “the residual sludge from sewage plants treating domestic or urban waste waters and from other sewage plants treating waste waters of a composition similar to domestic and urban waste waters”
"treated sludge " is defined in the Sludge (Use in Agriculture) Regulations 1989 (SI 1989/1263) as “sludge or septic tank sludge which has undergone biological, chemical or heat treatment, long-term storage or any other appropriate process so as significantly to reduce its fermentability and the health hazards resulting from its use”
“urban waste water ” is defined in Directive 91/271/EEC (EC, 1991b) as “domestic wastewater or the mixture of domestic waste water with industrial waste water and/or run- off rain water”
2.3. Materials considered
This report focused on a range of materials, namely:
Sewage sludge Septic tank sludge Livestock manure Compost Digestate Industrial wastes: Pulp and paper industry sludge Waste wood, bark and other plant material Dredgings from inland waters Blood and gut contents from abattoir Textile waste Tannery and leather waste Waste from food and drinks preparation Waste from chemical and pharmaceutical manufacture Sludge from the production of drinking water (predominantly inorganic) The Food and Environment Research Agency 11
Decarbonation sludge (predominantly inorganic) Waste lime and lime sludge (predominantly inorganic) Waste gypsum (predominantly inorganic)
2.4. Contaminants
A wide range of potential contaminants have been considered within this report. These include: PTEs Organic contaminants Animal/Human pathogens Plant pathogens Physical contaminants
Nitrogen, phosphorous and potassium which are contaminants, when in excess, were not considered, because their levels are commonly used to govern choice and use of fertiliser. Potentially toxic elements, organic contaminants and pathogens are discussed in more detail below. The presence of degradation products derived from the compounds above must also be considered. Davis and Rudd (1999) suggested that when waste arises from the processes described above it should be subjected to a detailed evaluation and risk assessment.
2.4.1. Potentially toxic elements
Potentially toxic elements (PTEs) include the metals copper (Cu), zinc (Zn), nickel (Ni), lead (Pb), mercury (Hg), cadmium (Cd), chromium (Cr) and the element arsenic (As). Potentially toxic elements include uranium (U) and vanadium (V). Total quantities of PTEs entering the soil from diffuse and agricultural sources are much higher than their losses through leaching and plant uptake. Therefore, PTEs tend to accumulate in topsoils over time, which could have long-term implications for the quality of agricultural soils (ADAS, Imperial College, JBA Consulting, 2005). Some metals such as Cd, Pb and Hg have no known biological function and might therefore cause serious health problems if entering the human food chain (ADAS, Imperial College, JBA Consulting, 2005).
Soil protection policies in the UK (Defra, 2004a) and the EU (CEC, 2002) aim to strategically reduce PTEs input to soils. A quantitative inventory of PTEs inputs to agricultural soils through the application of materials to land is therefore needed to find appropriate ways of reducing inputs to soils. Atmospheric deposition of metals also occurs but much smaller amounts are added to soils when compared with amounts added through application of “wastes” (ADAS, Imperial College, JBA Consulting, 2005). In a Defra report (ADAS, Imperial College, JBA Consulting, 2005) annual heavy metal inputs to agricultural land in England and Wales (2004) from all the sources considered within that report are summarised in Table 2.1.
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Table 2.1 Annual heavy metal inputs to agricultural land in England and Wales in 2004 (mg/kg)(ADAS, Imperial College, JBA Consulting, 2005) Source Zn Cu Ni Pb Cd Cr As Hg Atmospheric deposition 2485 638 180 611 22 84 35 11 Livestock manures 1666 541 47 44 4 32 15 <1 Sewage sludge 385 271 28 106 2 78 3 1 Industrial wastes 65 25 4 7 1 6 nd <1 Inorganic fertilizers 199 67 30 13 9 94 6 <1 Phosphate fertilisers 152 22 15 2.4 7.1 74 5.1 <0.1 Agrochemicals 22 5 0 0 0 0 0 0 Irrigation water 5 2 0 0 0 0 0 nd Composts 52 13 5 28 <1 6 nd <1 Corrosion 59 nd nd nd nd nd nd nd Dredgings 615 86 77 152 2 83 22 <1 Lead shot nd nd nd 18000 nd nd nd nd Footbaths 381 0 nd nd nd nd nd nd Total 5934 1648 371 18960 39 383 80 13 nd – no data
For Zn and Cu, 30% of the total annual inputs to agricultural land were from livestock manures, which were a much less important source for the other metals. Approximately 90% of total Pb inputs were from lead shot, whereas dredgings were shown to be an important source of Ni, Cr and As, accounting for 22-27% of total inputs. For Cd, atmospheric deposition was the most important source (56%) followed by the use of inorganic fertilisers (mainly phosphate fertilisers) and lime that accounted for 23% of total inputs. Over 85% of Hg inputs were from atmospheric deposition (ADAS, Imperial College, JBA Consulting, 2005). Therefore, atmospheric deposition was an important source for many metals to agricultural land in terms of total quantities on a national scale. However, input rates on an individual field basis were small when compared to inputs from sewage sludge, composts and livestock manures. With the exception for dredgings and lead shot, the highest inputs rates for most metals were from sewage sludge and composts, applied at 250 kg total N/ha/yr. However, sewage sludge represented < 25% and compost <1% of the total metals inputs and the land receiving these materials was relatively small (< 1% of agricultural land received sewage sludge (ADAS, Imperial College, JBA Consulting, 2005).
2.4.2. Organic compounds
There are a large and diverse variety of chemicals that could be included in an assessment of the inputs of organic contaminants to soils. For instance, some 90 000 industrial and domestically employed organic compounds have the potential to be present in materials derived from wastes and applied to land (O’Connor et al., 2005). Therefore, with the application of those materials to soils, a large number of organic contaminants might also potentially be applied. Potential sources of organic contaminants inputs to soils include atmospheric deposition, sewage sludge, animal manure, compost and other materials, the use of pesticides and irrigation water.
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The fate of organic contaminants in the aquatic environment and their potential for direct impact on human health via the food chain has been extensively studied, but only recently has attention focused on the impacts of organic contaminants in soils. In a Defra report (ADAS, Imperial College, JBA Consulting, 2005) identified seven broad categories of organic contaminants that are described in more detail below: Persistent organic pollutants (POPs) Bulk chemicals used domestically and in the industry Human pharmaceuticals Veterinary medicines Pesticides Biocides and personal care products (PCPs) Endocrine disrupting chemicals (EDCs)
Organic contaminants that are likely to be present in materials to be spread to land are summarised in Table 2.2 (ADAS, Imperial College, JBA Consulting, 2005).
Table 2.2 Organic contaminants found in different material types Industrial Human Veterinary Biocides Material POPs and bulk Pesticides pharmaceuticals medicines and PCPs chemicals Sewage sludge x x x x NR x Manure x x x NR x NR Industrial wastes x x x x x x Compost x x x NR x NR Dredgings x x x x x X NR – not relevant
2.4.2.1. Persistent organic pollutants
Persistent organic pollutants (POPs) are organic compounds of natural or anthropogenic origin that are resistant to photolytic, chemical and/or biological degradation (UNEP, 1999). Specific characteristics of these compounds are low water solubility, high lipophilicity (dissolve in fats), which gives them the potential to bioaccumulate. POPs are also semi- volatile compounds and thus are able to be transported for long distances from the original source via the atmosphere and the aquatic environment (ADAS, Imperial College, JBA Consulting, 2005). Therefore, POPs are widely distributed and may be found at locations where they have not been used. Some POPs, including organochlorine pesticides, polychlorinated biphenyls (PCBs) and polychlorinated naphthalenes (PCNs) have been produced to use within industry and their use is now limited (ADAS, Imperial College, JBA Consulting, 2005). Others, such as brominated flame retardants (BFRs) are still produced in large quantities as high as 69 000 tonnes worldwide (Eljarrat and Barceló, 2004).
Some POPs, including polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polycyclic aromatic hydrocarbons (PAHs) are accidentally formed or as a by-product of industry or combustion process (ADAS, Imperial College, JBA Consulting, 2005). The Food and Environment Research Agency 14
Polycyclic aromatic hydrocarbons (PAHs) are a large group of compounds that comprises of two or more joined benzene rings. Chemical characteristics vary for the different PAHs. PAHs are a by-product of incomplete combustion and their main source is from burning fossil fuels (Erhardt and Prüeß, 2001). These compounds are also semi-volatile which makes them highly mobile throughout the environment (ADAS, Imperial College, JBA Consulting, 2005). The major source of PAH emissions are road transport combustion that contributes for 58% of the emissions in 2007 (NAEI, 2009). Domestic and other industrial combustions were the second major sources of emissions in the same year (NAEI, 2009). Many PAHs are known or suspected to be carcinogens, the most potent being benzo[1]anthracene, benzo[a]pyrene and dibenz[ah]anthracene (Erhardt and Prüeß, 2001).
Polychlorinated biphenyls (PCBs) are substances produced by chlorination of biphenyl. These are stable compounds, with low volatility and resistant to degradation at high temperatures (Erhardt and Prüeß, 2001). PCBs used to be widely used industrial chemicals used in dielectric fluids in electrical transformers and capacitors, hydraulic fluids, cutting and lubricating oils and additives in a vast number of materials such as paints, sealants and adhesives (ADAS, Imperial College, JBA Consulting, 2005). Their use has been banned since the late 1970s. There are 209 congeners (i.e. related chemicals) and PCBs are characterised by having low solubility and vapour pressure and are lipophilic, with high solubility in non- polar solvents, oils and fats (Eljarrat and Barceló, 2004).
Polychlorinated dibenzo-p-dioxins and -furans (PCDD/Fs) may form during the production of chlorinated compounds or during combustion processes (Erhardt and Prüeß, 2001). Waste incineration and coal combustion are the main sources of these compounds in the environment (ADAS, Imperial College, JBA Consulting, 2005). Dioxins and furans are persistent compounds, lipophilic, ubiquitous and bioaccumulate. They are also highly toxic, very stable compounds with extremely low water solubility. Only 17 of the 75 dioxin congeners and 135 furan congeners, which are chlorine substituted at all four lateral positions (the 2,3,7,8-substituted) are of particular interest due to their toxicity (ADAS, Imperial College, JBA Consulting, 2005). Analysis of PCDD/Fs is generally restricted to the eight tetra- to heptachlorinated homologue sums and the 17 2,3,7,8- substituted congeners. The 25 separate concentrations from this kind of analysis are often condensed into a single number, the toxicity equivalent (TE) that is calculated by summing the concentration and the toxicity of the analyte relative to 2,3,7,8-tetrachlorinedibenzodioxin, the most toxic PCDD/F congener (ADAS, Imperial College, JBA Consulting, 2005). These relative toxicities are referred to as toxicity equivalency factors (TEFs; McLachlan et al., 1996). Stricter controls are currently in place to limit the emissions of PCDD/Fs (ADAS, Imperial College, JBA Consulting, 2005). Polychlorinated naphthalenes (PCNs) have been used in different industries, including cable insulation, wood preservation, engine oil additives, electroplating masking compounds, feedstock for dye production, dye carriers, capacitors and refractive testing oils (ADAS, Imperial College, JBA Consulting, 2005). In the UK, the total production was estimated at 6,650 t (NAEI, 2003), but these compounds have not been produced in the UK for 30 years. Therefore, potential sources are thought to be the disposal routes of capacitors and engine oil, where the majority of PCNs is produced, as well as during incineration, where PCNs have been detected in incinerators emissions and are thought to be produced from the The Food and Environment Research Agency 15
combustion of PAHs (ADAS, Imperial College, JBA Consulting, 2005). Another source of PCNs emissions are landfills (NAEI, 2003).
2.4.2.2. Bulk industry and domestic chemicals
A large amount of organic compounds are produced for industrial and domestic purposes. Since these compounds comprise many chemicals, some have been selected on the basis of their significance in wastewaters and water systems (ADAS, Imperial College, JBA Consulting, 2005). Pollutant Release and Transfer Registers (PRTRs), which is a catalogue of potential harmful pollutant released or transferred to the environment from a variety of sources, include 104 substances in the proposed changes to the UK PRTR water for 2005 to 2007 (EA, 2005). With the exception of 10 inorganic elements, all other compounds are organic contaminants (ADAS, Imperial College, JBA Consulting, 2005). This list includes POPs, industrial bulk chemicals and pesticides. A set of criteria based on persistence, bioaccumulation and toxicity has been developed by the UK Chemicals Stakeholder Forum (CSF; Defra, 2005a) and applied to the high volume production chemicals (> 1000 t per year) used in the UK. Approximately 70 compounds meet the criteria (Defra, 2005a).
Some of the largest volumes of bulk chemicals produced include surfactants used in the manufacture of detergents plasticizing agents and solvents (ADAS, Imperial College, JBA Consulting, 2005). Total consumption of surfactants in Europe for industrial and domestic purposes was 1.7 million tonnes in 2000, 85% of which used in domestic products (CETOX, 2000).
Linear alkylbenzene sulphonates (LAS) are widely used anionic surfactants in detergents and cleaning products (Erhardt and Prüeß, 2001). LAS are not generally regarded as toxic and were not included within the list of Priority Hazardous Substance within the Water Framework Directive (WFD), in the UK PRTR or recognised as a chemical of concern by the UK CSF. Risk assessments concluded that the ecotoxicological parameters of LAS have been sufficiently characterized and that the ecological risk of LAS is judged to be low (HERA, 2004; OECD, 2005). LAS have also been reported to be readily degradable under aerobic conditions, whereas it was stable under anaerobic conditions (Madsen et al., 1997).
Nonylphenol ethoxylates (NPEs) were extensively used as surfactants in hygienic products, cosmetics, cleaning products, and in emulsifications of paints and pesticides (Erhardt and Prüeß, 2001). These chemicals are listed in the WFD Priority Hazardous Substances due to concerns regarding the endocrine disrupting properties exhibited by the breakdown products of NPEs, the nonylphenols (NPs). It is included in the proposed UK PRTR list for water and NP is on the UK CSF list of chemicals of concern. Therefore, the use of NPEs is decreasing in the UK, with voluntary removal from the market occurring within a Voluntary Agreement on risk reduction for NP and NPEs (Defra 2004b). 4-nonylphenol is a degradation product of non-ionic alkylphenol polyethoxylate surfactants (Jones and Northcott, 2000). Octylphenols, which are a related group of chemicals used as surfactants, are also a group under review of the WFD Priority Substances and are included in the UK PRTR for water, the UK CSF list and in the UK Voluntary Agreement on risk reduction for NP and NPEs (Defra, 2004b).
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Plasticisers and additives are added to polymers to give plastics useful properties such as resistance to fire, strength, flexibility and colour (ADAS, Imperial College, JBA Consulting, 2005). These chemicals are mainly used as softeners in plastic, and other uses include additive functions in paints, lacquers, glues and inks (Erhardt and Prüeß, 2001). DEHP is a WFD proposed Priority Substance and is on the proposed UK PRTR for water but does not appear on the UK CSF list. There are five phthalate plasticizers: di(2-ethylhexyl)phthalate (DEHP), diisodecyl phthalate (DIDP) and diidononyl phthalate (DINP), butyl benzyl phthalate (BBP) and di-n-butyl phthalate (DBP). Of these compounds, DEHP is the most used and accounts for 51% of the market (Erhardt and Prüeß, 2001; HSDB, 2000). The majority of plasticizers used (> 90%) are phthalate-based compounds and are mainly used to plasticize PVC (polyvinyl chloride; CSTEE, 1999). Concentrations of phthalates in PVC range from 15 to 50%. Since phthalates are not chemically combined with PVC they are slowly released to the environment during use of after disposal (ADAS, Imperial College, JBA Consulting, 2005). Worldwide, global production of DEHP was estimated to be approximately 2 million tonnes (Koch et al., 2003a,b).
Adsorbable organic halogen compounds (AOX) are a wide range of compounds defined by the binding of a halogen containing chemical to activated carbon. The formation of AOX has been reported following drinking water disinfection by both chlorination and ozone. These disinfection processes may lead to the formation of trihalomethanes with bromine derivatives also formed if bromine is present in the water (Erhardt and Prüeß, 2001). The main sources of AOX arise from the use of chlorinated wood polymers (lignin, polyphenols and cellulose) and printing inks in the bleaching process of paper pulp (Gibbs et al., 2005). Other industries, including the manufacture of polyvinyl chloride (PVC) and waste incineration are also important sources of AOX (Erhardt and Prüeß, 2001).
Solvents are widely used chemicals within the industry and include chemicals such as benzene, carbon tetrachloride, dichloroethane, tri- and tetrachloroethene, and di- and trichloromethane. With the exception of dichloroethane, all these compounds are listed on the proposed UK PRTR for water (EA, 2005). Benzene, dichloromethane and trichloromethane are WFD priority substances.
Other substances that are used as intermediates during production/synthesis processes include hexachlorobutadiene (HCBD), which is a proposed UK PRTR list for water, and C 10-13 chloroalkanes, that are included on both the UK PRTR and the UK CSF list. Lecloux (2004) reported that the commercial production of HCBD has been virtually eliminated in Europe. Flame retardants are used in the textile industry, in plastics, packaging material, polyurethane foam for use in furniture and upholstery, electronic equipment, aircraft and motor vehicles (ADAS, Imperial College, JBA Consulting, 2005). There are 30 different aromatic, aliphatic and inorganic flame retardants, most of which contain halogens (Litz, 2002). Flame retardants that are of concern are polybrominated diphenyls that have similar properties to PCBs and have restricted usage, polybrominated diphenylethers (PBDEs) and tetrabromobiphenol A (TBBP-A) that have similar properties to dioxins (ADAS, Imperial College, JBA Consulting, 2005). These compounds are persistent and may bioaccumulate in the environment (ADAS, Imperial College, JBA Consulting, 2005). Brominated flame retardants may make up as much of 10 to 30% of the plastics used (e.g. printed circuit The Food and Environment Research Agency 17
boards, computer housings and other electronic equipment; Eljarrat and Barceló, 2004). Brominated flame retardants have been included in the list of priority pollutants of the Commission for the Protection of the Marine Environment of the North-East Atlantic (OSPAR).
The most widely used PBDEs are nominally deca-, octa- and penta- brominated forms. Most of the inputs into the environment are from volatilization during the service life of the foam, from weathering and wearing of the products in which the foam is present and during disposal and recycling operations (ADAS, Imperial College, JBA Consulting, 2005). The most important five brominated compounds have been prioritised for risk assessment at the European level and two of these, pentaBDE and octaBDE, have been banned from the European market in 2004 (EPCEU, 2003). PentaBDE is a WFD Priority Hazardous Substance and is listed in the UK CSF (Defra, 2005a). Brominated diphenyl ethers are also on the proposed UK PRTR for water (EA, 2005). A series of reviews regarding the effects of brominated flame retardants in health and the environment have been published in the literature: special volume of Environment International (Vol 29 (6):663-885), on the State-of-Science and Trends of BFRs in the Environment (Letcher, 2003), and also on BFRs in the environment (Wit, 2002).
Chlorobenzenes (CBs) were mainly used as intermediates during pesticide and other chemicals synthesis. Examples of chlorobenzenes are 1,4-DCB, which is used in deodorants and as a moth repellent, and the higher chlorinated benzenes TCBs and 1,2,3,4-TeCB, which are used as components of dielectric fluids. All TCB isomers, PCB and HCB are included on the UK PRTR list for water (EA, 2005).
Pentachlorophenol (PCP) was used for timber preservation and as a textile preservative. Production of PCP was banned in the EU in 1992 and its use as intermediate in the chemical industry was banned in 2000 (ADAS, Imperial College, JBA Consulting, 2005). PCP is a proposed UK PRTR list compound (EA, 2005). The main source of this compound is from wastewater collection systems from industrial releases, and also diffuse inputs from in surface water runoff.
The final compound to be considered is methyl tertiary butyl ether (MTBE) that is widely used as an oxygenate of unleaded petrol. It can be blended with petrol in any proportion up to 15% to achieve the required octane level of the fuel. In the EU the maximum permitted level is up to 5% by volume in petrol but average levels are lower than this value (~1.6% in the EU and < 1% in the UK; ADAS, Imperial College, JBA Consulting, 2005). The estimated annual production of MTBE in the EU is 3 million tonnes. MBTE is highly soluble in water and mobile in soil and is generally reported as persistent (Squillace et al., 1998). In Europe, a risk evaluation was performed for MTBE (CEC, 2001) and it was concluded that it is not carcinogenic, mutagenic or a reproductive toxin and thus does not represent a risk to human health or require further risk reduction measures to protect the terrestrial environment (ADAS, Imperial College, JBA Consulting, 2005). To protect groundwater, measures were considered necessary for prevention of spillages and leakage of underground storage tanks (CEC, 2001).
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2.4.2.3. Human pharmaceuticals
Pharmaceuticals from a wide spectrum of therapeutic classes are used in human and veterinary medicine worldwide. Pharmaceutically active compounds are defined as substances used for prevention, diagnosis or treatment of a disease and for restoring, correcting, or modifying organic functions (Daughton and Ternes, 1999). Volumes of selected pharmaceuticals sold in the UK and used in human therapy are summarized in Table 2.3. Table 2.3 Volume of pharmaceutically active compounds sold in the UK (kg/year; data from EA, 2008b) Therapeutic class Compound UK, 2004 Antibiotics Macrolides Azithromycin 756 Clarythromycin 8 807 Erythromycin 48 654 Penicillins Penicillin V 32 472 Amoxicillin 149 764 Sulfonamides Sulfamethoxazole 3 113 Sulfadiazine 362 Quinolones Ciprofloxacin 16 445 Tetracyclines Tetracycline 2 101 Other Trimethoprim 11 184 Analgesics and anti - inflammatories Acetaminophen 3 534 737 Acetylsalicylic acid 177 623 Diclofenac 35 361 Ibuprofen 330 292 Naproxen 33 580 Beta-blockers Acebutolol 943 Atenolol 49 547 Metoprolol 3 907 Propranolol 9 986 Hormones Progesterone 751 Lipid regulators Fibrates Gemfibrozil 1 418 Fenofibrate 2 815 Statins Simvastatin 14 596 Selective serotonin Fluoxetine 4 826 reuptake inhibitors Paroxetine 2 663 Citalopram 4 799 Other classes Antiepileptic Carbamazepine 52 245
In human therapy, most medical substances are administrated orally. After administration, some drugs are metabolised, while others remain intact, before being excreted. Therefore, a mixture of pharmaceuticals and their metabolites will enter municipal sewage and sewage treatment plants (STP; Kümmerer, 2004). During sewage treatment, pharmaceuticals can undergo different fates: microorganisms (e.g. activated sludge) degrade the pharmaceutical and convert it to water and carbon dioxide (e.g. aspirin);
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the drug or metabolites do not degrade and if they are lipophilic they will remain in the sludge and then be released onto soil following landspreading; the drug or metabolites do not degrade and if they are hydrophilic are released into the environment via the treated wastewater effluent. When this wastewater is used for irrigation pharmaceuticals will enter the soil environment.
Depending on their polarity, water solubility and persistence, some of these compounds may not be completely eliminated or transformed during sewage treatment and, therefore, pharmaceuticals and their metabolites may enter surface waters through domestic, industrial, and hospital effluents (Monteiro and Boxall, 2010). Sorptive pharmaceuticals could also present a risk to the environment through the disposal of sewage sludge on agricultural soils and eventual runoff to surface waters or leaching to ground waters after rainfall (Topp et al., 2008). The impact of human pharmaceuticals on the environment will depend on the usage amount, the degree of metabolism, degradation during storage prior to landspreading and toxicity to terrestrial organisms. Some pharmaceuticals, such as the sulphonamide and tetracycline antibiotics are used both in human and in animal health and thus it is not possible to differentiate between the sources entering the soil environment. In Europe, two thirds of all antibiotics are used in human medicine and one third for veterinary purposes (ADAS, Imperial College, JBA Consulting, 2005).
The data concerning the occurrence of human pharmaceuticals is limited for the UK. Nevertheless, most of the compounds summarized in Table 2.3 have been detected in effluents and surface waters worldwide. Monteiro and Boxall (2010) recently published a review on the occurrence and fate of human pharmaceuticals in different environmental compartments.
2.4.2.4. Veterinary medicines
Whilst human medicines are only used in therapy, veterinary medicines are widely used in feed additives for prevention, as growth promoters, and to maintain animal health. In intensive production systems, veterinary medicines are used routinely and wastes from these facilities tend to contain significant residues of drugs (ADAS, Imperial College, JBA Consulting, 2005). Major veterinary medicine groups that are in use in the UK are summarized in Table 2.4.
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Table 2.4 Major veterinary medicines in use in the UK (Boxall et al., 2004) Group Chemical class Major active ingredients Ectoparasiticides Organophosphates Diazinon Synthetic pyrethroids Flumethrin Cypermethrin Amidines Amitraz Antibiotics Tetracyclines Oxytetracycline Chlortetracycline Tetracycline Sulphonamides Sulfadiazine Sulfadimidine β-Lactams Amoxicillin Procaine penicillin Procaine benzylpenicillin Aminoglycosides Neomycin Apramycin Macrolides Tylosin Fluoroquinolones Enrofloxacin 2,4-Diaminopyrimidines Trimethoprim Pleuromutilins Tiamulin Lincosamides Lincomycin Clyn damycin Endectocides Macrolide endectins Ivermectin Doramectin Eprimomectin Pyrimidines Pyrantel Morantel Benzamidazoles Triclabendazole Fenbendazole Others Levamisole Nitroxynil
Hormones Altrenogest Progesterone Medroxyprogesterone Delmadinone Methyltestosterone Estradiol benzoate Ethinyl estradiol Antifungals Biguanide/gluconate Chlorhexidine Azole Miconazole Others Griseofulvin Anaesthetics Isoflurane Halothane Procaine Lido/lignocaine Euthanasia products Pentobarbitone Analgesics Metamyzole Tranquilizers phenobarbitone NSAIDs Phenylbutazone Caprofen Enteric bloat preparations Dimethicone Poloxalene
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For animals on pasture, veterinary medicines are directly excreted onto the soil and might be released as the parent compound or/and metabolites. When the animals are housed, the slurry and manure produced is collected and after a period of storage, applied onto land (ADAS, Imperial College, JBA Consulting, 2005).
Due to the large number of compounds in use, environmental monitoring of the compounds used as veterinary medicines is impractical. Therefore, Boxall et al. (2003) proposed a two- stage scheme for identifying and prioritizing compounds that have the greatest potential for environmental impact.
The first stage involved two steps: firstly, groups of substances were ranked according to their usage: usage higher than 10 tonnes per year were classed as high; usage quantities between 1 and 10 tonnes per year were classed as medium; those used in quantities below 1 tonne per year were classed as low; compounds for which usage could not be determined were classed as unknown. Secondly, the potential for substances to enter the environment was assessed based on information on the target group, route of administration, metabolism and the potential for the substance to degrade during storage. Substances were then classified as having high, medium, low or unknown potential to enter the environment.
In the second stage, a hazard assessment for compounds with high, medium or unknown potential to enter the environment and of high, medium, low or unknown usage is used. Compounds with medium potential and low usage are compounds with low potential to enter the environment and are not required to undergo hazard assessment. The compounds identified as having the greatest potential to cause environmental impacts from this prioritization exercise are listed in Appendix A.
2.4.2.5. Pesticides
Approximately 85% of a pesticide applied to crops may reach soil where it can undergo biological or chemical transformation (Margni et al., 2002). Some pesticides are mobile and readily biodegradable whereas others can be persistent, accumulate in the environment and be toxic to soil organisms (HRI, 2002). Application of sludge has been shown to increase the degradation of some pesticides (Sanchez et al., 2004). However, even if the pesticide degrades, Sinclair and Boxall (2003) reported that 30% of pesticide breakdown products were more toxic than the parent compound.
In livestock industry, farm operations are a significant source of pesticides to surface and groundwaters, and soil can also be contaminated by pesticide residues during washing and cleaning of used materials.
In sewage sludge, there is a concern over persistent pesticide compounds (especially organochlorines) due to the potential soil accumulation and long-term impacts in the environment (Bowen et al., 2003). Modern pesticides have been developed with higher biodegradability in the environment and also during wastewater treatment and thus their presence is less of a concern than in the past (ADAS, Imperial College, JBA Consulting, 2005).
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In compost, a number of chlorinated pesticides have been found but generally in very small amounts. Composts made with wood treated with high persistence/toxicity pesticides usually used as wood preservatives should be excluded from the production of marketable compost products or for land application.
However, the implications for soil quality mainly arise from direct applications of pesticides to crops and soils and from the application of animal manures rather than from inputs via agricultural application of sewage sludge.
2.4.2.6. Biocides and personal care products
Biocides and personal care products are widely used in domestic products such as clothing, furnishings and hygiene products (ADAS, Imperial College, JBA Consulting, 2005). They are discharged into sewage treatment plants and thus enter soils via the application of sewage sludge onto fields or when wastewater effluents are used for irrigation.
Triclosan is an antimicrobial agent that is used in a variety of products. Triclosan is used as an antiseptic agent, as a preservative in medical products, including hand disinfecting soaps, medical skin creams, and dental products (ADAS, Imperial College, JBA Consulting, 2005). It can also be found in everyday products such as toothpaste, mouthwash, soaps, household product cleaners, and also in textiles, shoes, and carpets. In Europe, approximately 350 tonnes of triclosan are used per year (Singer et al., 2002).
Organotins are the most widely used organometallic compounds that are used as agrochemicals and general biocides with a wide range of applications. Some organotins, such as tributyl-, triphenyl- and tricyclohexyltin derivatives are very toxic to the environment (Erhardt and Prüeß, 2001).
Musk xylene and musk ketone are used as substitutes for natural musk in perfumes, cosmetics, soaps and washing agents, fabric softeners, and air fresheners (Erhardt and Prüeß, 2001).
2.4.2.7. Endocrine Disrupting chemicals
While endocrine disrupting compounds can occur in many of the chemical classes described in the previous sections, the increasing concern over these substances justifies a separate category. A significant industrial xenobiotic oestrogen mimic is 4-tert-nonylphenol, which has been implied to be the dominant endocrine disruptor in some industrialised river reaches (ADAS, Imperial College, JBA Consulting, 2005). Polybrominated flame retardants, dioxins, and furans may possess some endocrine active properties. These compounds bioaccumulate, and additive effects may mean that low concentrations of xenobiotic endocrine active substances will have a cumulative negative effect (Johnson and Jürgens, 2003).
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2.4.3. Pathogens
In England and Wales, the number of reported cases of food-borne illness was estimated to be approximately 1.34 million in 2000 (Adak et al., 2002). The main causative agents were bacteria, especially Escherichia coli , Salmonella , Campylobacter and Listeria , the protozoan pathogens Cryptosporidium and Giardia, and viruses (ADAS, Imperial College, JBA Consulting, 2005). Routes by which pathogens may enter the food chain include the application of organic manures and water applied to crops, especially ready to eat crops that are not generally cooked before consumption (ADAS, Imperial College, JBA Consulting, 2005). It is important to note that the use of manures or water containing pathogens does not necessarily result in a higher risk to food safety since subsequent treatments such as washing or cooking may limit the potential for disease transmission.
Sources of biological contaminants to soils are through the application of sewage sludge and septic tank sludge, livestock manures, irrigation water, compost and industrial wastes. From these sources, as a result of the large quantities involved, the common prevalence of pathogens and the relative lack of controls in place, the application of livestock manures to agricultural land and deposition during grazing in the field is the most important source of enteric pathogens to soils (ADAS, Imperial College, JBA Consulting, 2005).
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3. CONCENTRATIONS OF CONTAMINANTS IN MATERIALS SPREAD ONTO LAND
3.1. Sewage sludge
3.1.1. Introduction
Within this report, the term sewage sludge only covers residual sludge from sewage plants treating domestic or urban waste waters and from other sewage plants treating waste waters of a composition similar to domestic and urban waste waters. This sludge has been treated by a biological, chemical or heat treatment that reduces fermentability and possible health hazards associated from its use. In most cases, data collected did not specify the form of the sludge (e.g. pelletized, cake, etc).
Sewage sludge is the residue collected following treatment of waste water. Sewage sludge contains significant proportions of nitrogen, phosphorus and organic matter that, when used in agriculture, are enough to supply nutrient requirements for most crops (DoE, 1996a). Other benefits arising from sludge application are stabilisation and improvement of soil structure, improvement of pH, and increased water holding capacity (helps reducing flood risk; DoE, 1996a). However, it may also contain traces of many contaminating substances used in our modern society. During wastewater treatment, potentially toxic elements and hydrophobic organic contaminants in wastewater largely transfer to the sewage sludge, which may cause potential implications on the further usage of sludge (IC Consultants, 2001). The production of sewage sludge is increasing and its use as fertilizer to agricultural fields is consistent with the EC policy of waste recycling. However, sludge quality must be improved and monitored to secure that the application to land is the most sustainable option (IC Consultants, 2001).
3.1.2. Treatment
Raw or untreated sewage sludge cannot be applied onto agricultural land, whether it is used for food or non-food purposes (WRc, 2009). Therefore, sewage sludge needs to be treated before land application. Conventional treated sludge refers to sludge treated by biological, chemical or heat treatment, and ensures that 99% of pathogens have been eliminated (The Safe Sludge matrix, 2001). The most common form of treatment is anaerobic digestion. Enhanced treated sludge is a term to describe treatment processes that are capable of eliminating the pathogen Salmonella and 99.9999% pathogens (The Safe Sludge matrix, 2001).
Examples of sewage sludge treatment processes are summarized in Table 3.1.
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Table 3.1 Examples of sewage sludge treatment processes (DoE, 1996a) Process Descriptions Sludge Pasteurisation Minimum of 30 minutes at 70°C or minimum of 4 hours at 55°C (or appropriate intermediate conditions), followed in all cases by primary mesophilic anaerobic digestion. Mesophilic Anaerobic In a primary sludge digestion, a mean retention period of at least 12 days at a Digestion temperature of 35±3°C or of at least 20 days primary sludge digestion at a temperature of 25±3°C, followed in each case by a secondary sludge digestion which provides a mean retention period of at least 14 days. Thermophilic Aerobic Mean retention period of at least 7 days digestion. All sludge to be subject to a Digestion minimum of 55°C for a period of at least 4 hours. Composting (Windrows or The compost must be maintained at 40°C for at least 5 days and for 4 hours Aerated Piles) during this period at a minimum of 55°C within the body of the pile followed by a period of maturation adequate to ensure that the compost reaction process is substantially complete. Lime Stabilisation of Addition of lime to raise pH to greater than 12.0 and sufficient to ensure that the Liquid Sludge pH is not less than 12 for a minimum period of 2 hours. The sludge can then be used directly. Liquid Storage Storage of untreated liquid sludge for a minimum period of 3 months. Dewatering and Storage Conditioning of untreated sludge with lime or other coagulants followed by dewatering and storage of the cake for a minimum period of 3 months. If sludge has been subject to primary mesophilic anaerobic digestion, storage to be for a minimum period of 14 days.
3.1.3. Contaminants
3.1.3.1. PTEs
During sewage treatment, the majority of metals transfer from wastewater to sewage sludge and may accumulate. The application of sludge to land is mainly dictated by nutrient content (phosphorus and nitrogen). However, the sludge quality regarding potentially toxic elements should be considered in terms of the long-term sustainable use of sludge onto land (IC Consultants, 2001).
Concentrations
Concentrations of PTEs and elements reported in sewage sludge in the UK are summarised in Table 3.2.
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Table 3.2 Concentrations of metals/elements in UK sewage sludge in mg/kg dry weight Sewage sludge survey Data from Gendebien et al., 1999 Sleeman, 1984 EA, 2007 Metal/element England and Wales England and Wales Scotland Northern Ireland UK (n=555) Mean Mean Median n Mean Median n Mean Median n Range Mean Antimony NA NA NA NA NA NA NA NA NA NA <2-572 8 Arsenic NA 6 2.5 861 3.2 3.67 35 NA NA NA <2-123 6 Barium NA NA NA NA NA NA NA NA NA NA 23-3104 323 Bismuth NA NA NA NA NA NA NA NA NA NA <2-557 10 Bromine NA NA NA NA NA NA NA NA NA NA 4-1049 38 Cad mium 1.56 3.4 1.6 1049 1.4 1.2 57 2.1 1.4 27 <2-152 9 Chromium 104.10 163 24 1220 81 37 59 50 29 27 4-23195 197 Cobalt NA NA NA NA NA NA NA NA NA NA <2-617 10 Copper 311.27 565 376 1223 620 254 59 583 350 27 69-6140 589 Fluorine NA 224 161 820 91 65 25 NA NA NA NA NA Gallium NA NA NA NA NA NA NA NA NA NA <2-15 3 Germanium NA NA NA NA NA NA NA NA NA NA <2-9 <2 Iron NA NA NA NA NA NA NA NA NA NA 2480-106812 16299 Lead 138.26 221 96 1218 271 170 59 156 106 27 43-2644 398 Manganese NA NA NA NA NA NA NA NA NA NA 55-13902 376 Mercury 1.03 2.3 1.4 1200 2.5 2 49 2.4 2 27 <2-140 4 Molybdenum NA 8 5 883 2.9 3.65 40 NA NA NA <2-154 5 Nickel 37.13 59 20 1219 31 20 56 38 22.5 27 9-932 61 Niobium NA NA NA NA NA NA NA NA NA NA <2-41 5 Rubidium NA NA NA NA NA NA NA NA NA NA <2-232 23 Selenium NA 2 1.6 879 0.86 1.08 25 NA NA NA <2-15 3 Silver NA NA NA NA NA NA NA NA NA NA <2-1252 25 NA- not available n – number of samples
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Table 3.2 (cont.) Concentrations of metals/elements in UK sewage sludge in mg/kg dry weight Sewage sludge survey Data from Gendebien et al., 1999 Sleeman, 1984 EA, 2007 Metal/element England and Wales England and Wales Scotland Northern Ireland UK (n=555) Mean Mean Median n Mean Median n Mean Median n Range Mean Stro ntium NA NA NA NA NA NA NA NA NA NA 45-1335 158 Tellurium NA NA NA NA NA NA NA NA NA NA <2-2 <2 Thallium NA NA NA NA NA NA NA NA NA NA <2-5 <2 Tin NA NA NA NA NA NA NA NA NA NA 19-683 90 Titanium NA NA NA NA NA NA NA NA NA NA 355-11629 1677 Tungsten NA NA NA NA NA NA NA NA NA NA <2-1418 7 Uranium NA NA NA NA NA NA NA NA NA NA <2-18 2 Vanadium NA NA NA NA NA NA NA NA NA NA 7-660 29 Yttrium NA NA NA NA NA NA NA NA NA NA <2-34 8 Zinc 763.49 802 559 1223 644 508 50 668 745 27 279-27600 1144 Zirconium NA NA NA NA NA NA NA NA NA NA 14-2500 91 NA- not available n – number of samples
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3.1.3.2. Organic compounds
Adsorption to the sludge is the fate of many organic compounds during sewage treatment (ADAS, Imperial College, JBA Consulting, 2005). The range of organic contaminants detected in sewage sludge is much greater than the number of potentially toxic elements in sludge that are monitored and controlled, with 42 compounds being regularly detected in sewage sludge (IC Consultants, 2001). The Water Framework Directive (WFD) aims to cease the emissions, discharges and losses of priority hazardous substances including PAHs, PCBs and PCDD/Fs. PAHs and PCDD/Fs produced during incineration are subjected to stringent air quality emission standards and therefore, further reducing the inputs of these organic compounds as well as PCBs in sewage sludge seems unlikely (ADAS, Imperial College, JBA Consulting, 2005).
Concentrations
A summary of the range concentrations of organic contaminants by class reported in sewage sludge in the UK is presented in Table 3.3. All data, including individual compounds can be found in Appendix B.
Table 3.3 Summary of range concentrations (minimum value, highest maximum and highest mean reported within the class) for organic contaminants detected in UK sewage sludge in mg/kg dry weight (unless otherwise stated; UKWIR, 1995; Wild and Jones, 1992; Wilson et al., 1997; Wild et al., 1993; Wang et al., 1995; Rogers et al., 1989; Nicholls et al., 2001; Bowen et al., 2003; McIntyre and Lester, 1982; McIntyre and Lester, 1984; Stevens et al., 2001; Stevens et al., 2003; Leschber, 2006; Sewart et al., 1995; Jones and Northcott, 2000) Contaminant Minimum Maximum Mean (highest) Alkyl and aromatic am ine 2.2 3.8 2.32 Carbonyl 1.4 2.3 10.1 Chlorinated phenols 0.0004 93.3 1.36 Chlorobenzenes ND 192000 108875 Halogenated aliphatics 0.0001 93.1 7.97 Monocyclic hydrocarbons 0.0046 22.1 6.3 and heterocycles Non -halogenated NA NA 540 aliphatics Organo tins 0.01 1.3 0.36 Pesticides ND 70 0.042 Phthalate acid esters/ trace 430 NA Plasticizers ∑ PAHs 1 246 36 ∑ PCBs 44 μg/kg dw 180 μg/kg dw 81 μg/kg dw
∑PCDD/Fs (C 11 -C18 ) 8.880 μg/kg dw 428.00 μg/kg dw 75.3 μg/kg dw PCNs nd 78 μg/kg dw 31 μg/kg dw Surfactants 450 25300 NA Synthetic musks ND 81 27 dw – dry weight
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Persistent organic pollutants controls introduced between 1980 and 1990 have been effective in reducing the main sources of PAHs, PCBs and PCDDs/Fs (Smith, 2000). These controls also reduced inputs to urban wastewater and therefore concentrations of POPs in sewage sludge were reduced.
A screening study performed by Bowen et al (2003) showed that some Priority Substances are present at measurable concentrations. In the same study, NPEs in sewage sludge in UK sewage treatment plants (STPs) with concentrations ranging from 1.0 to 350 μg/L with an average value of 79.5 μg/L (Bowen et al., 2003). In Europe and in the UK, NPE concentrations (including nonylphenol) in sludge ranged from 10 to over 1000 mg/kg, which would exceed the proposed limit of 10 mg/kg discussed by the European Commission in proposals for the future revision of the sludge directive (EC, 2000b). Octyl phenols have not been detected in UK STPs (Bowen et al., 2003).
Chlorobenzenes have been reported as one of the important groups of POPs in sewage sludge and sludge-treated soil (Wang and Jones, 1994; Beck et al., 1995). In contrast, Bowen et al (2003) did not detected chlorobenzenes in influents to STPs due to their withdrawal from use.
Bowen et al. (2003) also reported that concentrations of solvents in crude sewage were very variable between sites and substances. Carbon tetrachloride was below detection limits in STPs and benzene and dichloroethane were almost entirely below detection limits. Trichloroethene and tetrachloroethene were detected at 14 and 21 STPs (out on 30 STPs sampled), respectively. Dichloromethane and trichloromethane (chloroform) were found in most influent samples up to 5 μg/L. Bowen et al (2003) did not detect C10-13 chloroalkanes and HCBD in any influent from STPs in the UK, and concluded that since they are used as intermediates in industrial processes they are unlikely to be present in significant quantities in diffuse inputs to sewerage systems.
DEHP is one of the most frequently detected priority pollutants in industrial and municipal sewage sludge. DEHP has a draft limit proposed for sludge of 100 mg/kg dry weight (EC, 2000b).
A large part of LAS is adsorbed onto sewage sludge during the primary sewage treatment and therefore will not go through the secondary sewage treatment, which is the aeration tank, and thus not degraded during sewage treatment (De Wolfe and Feitjel, 1997).
In a study of 12 liquid digested sewage sludge’s, no correlations have been found between concentrations of 15 volatile organic compounds (VOC) (e.g. chloroform, benzene), the volume of industrial input to STPs, influent treatment, population served and sludge dry solids content (Wilson et al., 1994).
Pentachlorophenol was not detected in any influent samples from a UK STP in screening study performed by Bowen et al (2003) and it was concluded that the widespread occurrence of PCP in wastewater effluent and sludge is very unlikely.
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Regarding pharmaceutical compounds, data on the concentrations of pharmaceuticals in sludge applied to land is very limited for the UK. Removal of pharmaceuticals during sewage treatment is very variable and depends on the pharmaceutical. Whereas high removal has been reported for some pharmaceuticals (e.g. salicylic acid, acetaminophen), very low removal has been reported for others (e.g. carbamazepine, diatrizoate; Monteiro and Boxall, 2010). Golet et al. (2002) and Göbel et al. (2005) reported the occurrence of antibiotics in sewage sludge samples from Switzerland. Average concentrations of sulfonamide and macrolide antibiotics, and trimethoprim ranged from 28 to 68 μg/kg of dry weight (Göbel et al., 2005). The antidepressant fluoxetine was detected in treated sludge samples from nine different STPs in the US (Kinney et al., 2006). In North America, the occurrence of carbamazepine (Kinney et al., 2006) and its major metabolites has been reported in raw and treated sludge samples (Miao et al., 2005). In Germany, Ternes et al. (2002) detected estrone and 17β-estradiol in activated and digested sludge up to 37 μg/kg and 49 μg/kg, respectively.
Runoff of pharmaceuticals from an agricultural field following the application of sewage sludge has also been reported (Topp et al., 2008). Recent investigations also show that around 90% of the potential oestrogenic activity in urban wastewater is reduced during sewage treatment and that less than 3% is transferred to the sludge (ADAS, Imperial College, JBA Consulting, 2005).
3.1.3.3. Pathogens
Concerns of using sewage sludge in agriculture led to the development of the “Safe Sludge Matrix” between the UK Water Industry and the British Retail Consortium in January 1999. Under the terms of the “Matrix”, the use of raw sewage sludge on agricultural land growing food crops ceased at the end of 1999 and sludge used to grow non-food crops ceased at the end of 2005 (ADAS, Imperial College, JBA Consulting, 2005). Therefore, conventional sewage sludge treatment ensures that 99% of pathogens have been destroyed and enhanced treatment of sewage sludge ensures that it is free from Salmonella and 99.9999% of pathogens have been destroyed (ADAS, Imperial College, JBA Consulting, 2005).
3.1.4. Legislation
Legislation and voluntary initiatives for the use of sewage sludge on land and what is covered within the legislation is summarized in Table 3.4. The Sewage Sludge Directive (EC, 1986) regulates the use of sludge in agriculture to prevent harmful effects for soil, animals and humans and this is being reviewed this year (2009).
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Table 3.4 Legislation/ voluntary initiatives on the use of sludge Title Measures P/L/V PTEs OCs Pathogens EC Sludge Directive 86/278/EEC European legislation on sludge use in L D I D (1986) agriculture Implements Sludge Directive. Sets maximum permitted heavy metal Sludge (Use in Agriculture) contents in soils where sludge can be L D I D Regulations (1989) applied, and maximum sludge metal loading rates Draft revision of Sludge Proposes new limits on heavy metal and L D D D Directive (suspended) OC additions with sludge Draft Revised Sludge (Use in Agriculture) Regulations (and Enshrines the requirements of the Safe L D I D associated revised Code of Sludge Matrix Practice) Manual of Good Practice for the Forestry Commission. Limits for sludge Use of Sewage Sludge in application in forestry (same as for V D I D Forestry (1992) agriculture) Manual of Good Practice for the WRc. Limits for sludge application in land Use of Sewage Sludge in Land V D I D restoration (same as for agriculture) Reclamation (1999) Code of Practice for Agriculture Guidelines based on sludge regulations V D I D (1996) Specifies treated sludge types that can Safe Sludge Matrix (2000) be applied to agricultural land and V I I D harvest/grazing intervals PTEs – potentially toxic elements; OCs – organic compounds P-Policy, L- Legislation, V-Voluntary measure D - Direct, I - Indirect . Legislation has a direct effect if its purpose is to control/limit inputs of a contaminant to soil. Indirect legislation may have implications for contaminant inputs to soil without this being its primary purpose.
Contaminant limits available in legislation, policy or voluntary initiatives for sewage sludge applied to land in Europe and UK are summarised in Table 3.5. The UK regulations do not set maximum metal concentration limits values in the applied sludge, but instead set maximum concentrations limits in soils receiving sludge and maximum annual metal loadings rates, as a 10 year average.
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Table 3.5 Contaminants limits available in legislation, policy or voluntary initiatives for sewage sludge applied to land in Europe and UK (in mg/kg dry matter, unless otherwise stated) European Union UK Sewage sludge Soils following the application of sewage sludge Contaminants Current Proposed Sludge (Use in Agriculture) Regulations Sewage sludge Working Document Code of Practice for the Agricultural Use of Sewage sludge 1989 directive 86/278/EEC on sludge- 3rd draft PTEs /elements Maximum permitted annual average rate of Limit according to soil pH PTE addition over a 10 year period (kg/ha) 5.0<5.5 5.5<6.0 6.0 -7.0 >7.0 5.0<5.5 5.5<6.0 6.0 -7.0 >7.0 Zn 2500-4000 2500 200 250 300 450 200 200 200 300 15 Cu 1000-1750 1000 80 100 135 200 80 100 135 200 7.5 Ni 300-400 300 50 60 75 110 50 60 75 110 3 For pH 5.0 and above Pb 750-1200 750 300 N/A N/A N/A 300 0.15 Cd 20-40 10 3 N/A N/A N/A N/A3 15 Hg 16-25 10 1 N/A N/A N/A 1 0.1 Cr N/A 1000 N/A N/A N/A N/A 400 15 Mb N/A N/A N/A N/A N/A N/A 4 0.2 Se N/A N/A N/A N/A N/A N/A 3 0.15 As N/A N/A N/A N/A N/A N/A 50 0.7 Fluoride N/A N/A N/A N/A N/A N/A 500 20 Organic Compounds AOX N/A 500 N/A N/A N/A LAS N/A 2600 N/A N/A N/A DEHP N/A 100 N/A N/A N/A NPE N/A 50 N/A N/A N/A PAH N/A 6 N/A N/A N/A PCB N/A 0.8 N/A N/A N/A PCDD/Fs N/A 100 ng TE/kg dm N/A N/A N/A NA – not available
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3.2. Septic tank sludge
3.2.1. Introduction
About 5% of the UK population is served by septic tanks and cesspits. There are no data on the quantities or composition of septic sludge applied to agricultural land. “Septic tank sludge” is defined as the residual sludge from septic tanks.
3.2.2. Contaminants
3.2.2.1. Heavy metal
Data on the chemical composition of septic tank sludge indicated that the Zn content was 650 mg/kg dry solids, which was less than the average zinc content in sewage sludge (802 mg/kg dry solids; ADAS, Imperial College, JBA Consulting, 2005). Whereas no other data was found for concentrations of PTEs in septic tank sludge, it has been reported that levels of metals in this sludge are usually low and that no metal contamination should arise when it is applied to land (Carlton-Smith and Coker, 1985).
3.2.2.2. Organic contaminants
As for sewage sludge, a range of organic compounds including pharmaceuticals, hormones, fragrances, and personal care products are expected to be present in septic tank sludge.
3.2.2.3. Pathogens
In regard to pathogen content, these wastes have a high potential to present a microbiological risk to man and animals since they mainly consist of human excreta and wastewaters (Davis and Rudd, 1999). No published data was found reporting amounts of pathogens in septic tank sludge. However, it can be assumed that the pathogen content will be similar to untreated sewage sludge.
Septic tank sludge is not covered by the “Safe Sludge Matrix” and can only be applied to land under a Waste Management Licence (SI, 2005/1728). It is likely that septic tank sludge is disposed into a sewage treatment plant and not directly applied to land. However, in some cases septic tank sludge is still spread untreated to land (EA, 2008a). Since septic tank sludge is not covered by the “Safe Sludge Matrix” several options are available for its use or disposal: - sludge can be taken to a sewage treatment works under a paragraph 10A exemption under the Environmental Permitting (England and Wales) Regulations 2007 (EA, 2009).; - taken to an appropriate licensed/authorised waste facility; or - spread to land under a Waste Management License.
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3.3. Livestock manure
3.3.1. Introduction
Within this report, the livestock manures considered are cattle manure (including dairy and beef slurry and dairy and beef farmyard manure), pig slurry and pig farmyard manure, sheep manure, horse manure, poultry manure (including layer manure and poultry litter ash) and broiler litter (including broilers, turkeys, pullets, other hens and other poultry).
Livestock manures are produced from animal production activities, with solid manures comprising a mix of excreta and bedding (normally cereal straw, wood shavings and sawdust), and liquid manures (i.e. slurry) composed of a mixture of excreta and waste water from farming activities (SORP, 2003). Around 96 million tonnes of farm manures are applied each year in the UK (Hickman et al., 2009). In 2003, from the total amount of applied manure, 81% were from cattle, 11% from pigs, 5% from poultry and 3% from sheep (SORP, 2003).
Farm manures, both solid and slurries are beneficially applied to agricultural land to meet crop nutrient requirements and to improve soil fertility. Most of the nutrients contained in livestock diets are excreted in dung and urine. Hence, manures contain valuable amounts of major plant nutrients (i.e. nitrogen, phosphorus and potassium), as well as other nutrients such as sulphur and magnesium and trace elements (SORP, 2003). The fertiliser value of manures and slurries is very variable from farm to farm and dependent on a range of factors including the type of livestock (species, breed and age), diet, type of production, housing system and waste handling system (Gendebien et al., 2001). However, farm manures can contain unwanted compounds such as PTEs, organic compounds (especially veterinary medicines) and pathogens.
As there is a limited retail market for these materials, agriculture and land restoration/reclamation provide the most sustainable re-use and recycling routes (SORP, 2003).
3.3.2. Treatment
Fresh solid manure or slurry can be applied to land, but should not be applied within 12 months of harvesting a ready-to-eat crop, including a minimum period of 6 months between the manure application and drilling/planting of the crop (Hickman et al., 2009). This is because manures can contain pathogens that may cause food borne illness. Therefore, the management and handling of farm manures, particularly the length of time they are stored, are important factors in the survival of microorganisms (Hickman et al., 2009). Examples of treatments for farm manures are presented in Table 3.6.
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Table 3.6 Examples of treatments for farm manures (Hickman et al., 2009) Treatment Definition Solid manures and slurries are batch stored for at least 6 months (with no Batch storage additions of fresh manure during this period). The manure should be treated as a batch and turned regularly (at least twice within the first 7 days) either with a front-end loader or preferably with a purpose-built compost turner. This should generate high Composting temperatures over a period of time (e.g. above 55 oC for 3 days) which are effective in killing pathogens and this temperature should be monitored. The compost needs to mature as part of the treatment process. The whole process should last for at least 3 months. Farm manures are put into a digester to produce digested solids and Anaerobic digestion liquids, which can be both used as fertilizers. It also produces biogas that can be used as a fuel or to generate energy.
Lime treatment of Addition of quick lime to raise the pH to 12 for at least 2 hours. It is an slurry effective method of inactivation of pathogens.
3.3.3. Contaminants
3.3.3.1. PTEs
PTEs , especially copper and zinc are present in livestock feeds at background concentration and can still be added as supplements for health and welfare reasons or as growth promoters. A number of international authorities and scientific bodies have published recommendations on trace elements allowances for farm livestock. There is evidence that the immune status and health of livestock may be enhanced with certain trace elements at levels above those considered to be necessary to maintain normal metabolism, growth production and reproduction (ADAS, 2002).
Concentrations
Concentration of PTEs in livestock manures and poultry litter ash are presented in Table 3.7.
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Table 3.7 Typical concentrations of PTEs in manures (ADAS, 2009) Livestock manures 2Poultry litter ash Metal Dairy slurry Dairy FYM Beef FYM Pig slurry Pig FYM Layer manure 1Broiler litter Fibrophos Cropcare /element (n=25) (n=18) (n=15) (n=49) (n=26) (n=17) (n=19) Mean (Min; Max) in mg/kg dw As NA NA NA NA NA 1.33 (0.29; 4.27) 0.67 (0.16; 2.35) NA NA Cd 0.16 (0.05; 1.17) 0.37 (0.05; 1.09) 0.32 (0.05; 0.703) 0.3 (0.05; 7.45) 0.44 (0.05; 1.26) 0.65 (0.05; 1.5) 0.26 (0.05; 0.73) NA NA Cr 2.94 (0.5; 13.83) 14.85 (0.05; 76.7) 16.92 (1.83; 43.10) 2.29 (0.5; 15.68) 22.65 (1.96; 190) 4.94 (1.81; 9.34) 4.64 (1.49; 10.3) NA NA Cu 175.5 (27.3; 1090) 51.5 (7.49; 164) 40.07 (12.40; 129) 279 (19.9; 1333) 199 (25.8; 707) 56.7 (7.97; 98.5) 84.5 (40.6; 127) 500 291 Mb NA NA NA NA NA NA NA 30 11 Ni 4.66 (2.02; 18.75) 11.28 (2.5; 40.5) 28.71 (2.5; 345) 3.49 (2.5; 30.9) 12.01 (2.5; 171) 19.86 (2.5; 177) 5.38 (2.5; 28.9) NA NA Pb 3.36 (1; 14.77) 6.71 (1.0; 24) 7.68 (1; 23.2) 3.92 (1; 16.2) 13.87 (1; 109) 3.56 (1; 6.08) 2.92 (1; 7.24) NA NA Se NA NA NA NA NA NA NA 5 3 Zn 232 (49; 1090) 141 (33; 311) 143 (35.8; 270) 870 (66; 5174) 631 (146; 1830) 287 (55.9; 463) 346 (152; 526) 2000 162 FYM- farm yard manure NA-not available 1- Includes broilers, turkeys, pullets other hens and other poultry. 2 - Data from analysis provided on the company websites or in published product information brochures. This material is sold as a fertiliser.
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3.3.3.2. Organic compounds
Some farm manures may contain contaminants such as residual hormones, antibiotics, pesticides and other undesirable substances (Kuepper, 2003). Detergents and cleaning agents might also be found since these are used to clean facilities. Steven and Jones (2003) quantified PCDD/Fs in samples of cattle, pig, sheep and chicken manure. TEQs ranged from 0.19 ng TEQ/kg dry solids for pig manure to 20 ng TEQ/kg dry solids for one cattle manure sample.
Boxall et al. (2003, 2004) have reviewed the environmental significance of veterinary medicines in the UK. Data for soil and manure concentrations of veterinary medicines were very limited for the UK. The available data presented by Boxall et al. (2003; 2004) for animal manures are listed in Table 3.8.
Table 3.8 Concentrations of veterinary medicines found in animal manures (Boxall et al., 2004) Concentration detected in ng/L Compound Therapeutic use Country (unless otherwise stated) Cattle faeces/manure [14 C] ceftiotur Antibiotic 11.3 – 216.1 mg kg -1 (equivalent) USA Chlortetracycline Antibiotic 7.6 ± 2.7 μg kg -1 Germany 12-75 μg kg -1 USA 0.3 ± 0.0 – 9.0 ±0.7 mg kg -1 Denmark 0.2-3.8 mg kg -1 (dry weight) Tanzania Ivermectin Endectocide 0.07-0.36 mg kg -1 (wet weight) Australia 0.353 mg kg -1 USA 13-80 μg kg -1 USA 0.24-0.27 USA Monensin Coccidiostat 0.7 – 4.7 Canada Sulphadimethoxine Antimicrobial 300-900 mg kg -1 Italy Tetracycline Antibiotic 2.5 ± 1.2 μg kg -1 Germany Pig faeces/manure Chlortetracycline Antibiotic 3.4 – 1001.6 μg kg -1 Germany Ivermectin Endectocide 0.22 – 0.24 mg kg -1 USA Tetracycline Antibiotic 44.4 – 132.4 μg kg -1 Germany Sheep faeces/manure Ivermectin Endectocide 0.63 – 0.714 mg kg -1 USA Poultry faeces/manure Chlortetracycline Antibiotic 22.5 μg g -1 Canada [14 C]narasin Antibiotic 1 ± 0.3 – 725 ± 60.3 μg kg -1 (equivalent) USA Horse faeces/manure Ivermectin Endectocide 0.05 – 8.47 μg g -1 USA
In another study, Haller et al. (2002) investigated six different sources of slurry from cattle and pig farms that used medicinal feed during a study to develop appropriate analytical techniques for determination of antibiotic in manures. Sulfamethazine was detected in all six samples whereas five samples contained its metabolite N-acetyl- sulfamethazine in concentrations 3 to 50 times below concentrations of the parent compound. Although this metabolite does not have antimicrobial characteristics, it can be transformed onto the parent compound in manure (Berger et al., 1986 as The Food and Environment Research Agency 38
cited in Haller et al., 2002). Total sulfonamide concentrations (sulfamethazine + sulfathiazole) were above than 20 mg/kg (fresh weight). Other sulfonamides such as sulfaguanidine, sulfadiazine, sulfamethoxazole and sulfadimethoxine were not detected in any of the samples. The slurry was collected over a period of time, including when no veterinary medicines were being administrated. In consequence, the manure was diluted with material from medication free time periods. The extent to which antibiotic contaminated slurry is diluted in this way depends on the size of the slurry storage tank, relative to the period over which the drug is being administered, and the rate of slurry production. Furthermore, degradation will take place during the storage period, suggesting that manure excreted directly in the field has the potential to contain much higher concentrations of antibiotic than material from housed stock, which may be diluted with uncontaminated slurry (Boxall et al., 2004). Reported concentrations of antibiotics in manures from this study are presented in Table 3.9.
Table 3.9 Sulfonamide and trimethoprim residues in manure samples in mg kg -1 fresh weight (Haller et al., 2002) Fattening Compound Mother pigs with farrows Fattening pigs calves Sample A B C D E F Sulfamethazine 8.7 (8.9) 5.5 3.3 0.23 0.13 (0.11) 3.2 4-N-acetyl-sulfamethazine 2.6 (2.7) 0.59 0.15 ND D D Sulfathiazole 12.4 (12.4) D ND 0.10 0.17 (0.17) ND Trimethoprim D ND ND ND ND ND Dried mass content (%) 3.3 3.4 1.8 3.7 3.2 1.1 Results determined by external calibration (and determined by standard addition in parenthesis for samples A and E) D – detected, but below 0.1 mg/kg ND- not detected
3.3.3.3. Pathogens
Animal manures contain pathogenic elements in variable quantities depending on the animal health. Pathogenic microorganisms such as Escherichia c. O157 , Salmonella, Listeria, Campylobacter, Cryptosporidium and Giardia have all been isolated from cattle, pig and sheep manures (ADAS, Imperial College, JBA Consulting, 2005). Of these, Salmonella is of particular concern with 323 reported isolations in pigs in the UK in 1998 and 37% of all isolates typing as multi-drug resistant S. typhimurium DT104. One study of fecal swabs taken from animals at an abattoir in North Yorkshire found that 13% of beef cattle, 16% of dairy cattle, 2% of sheep and < 1% of pigs produced faeces containing E. coli O157 (Chapman et al., 1997). A more recent study found E. coli O157 in 22 % of sheep and 16% of pig excreta samples that indicate that the prevalence among these species might be increasing (Hutchison et al., 2004). The most commonly pathogens found in poultry manure are Salmonella , and Campylobacter. Listeria might be present but it has not been regarded as a widespread problem. E coli have not been reported to date in UK poultry manures (ADAS, Imperial College, JBA Consulting, 2005). Pathogens found in manure are presented in Table 3.10. The Food and Environment Research Agency 39
Table 3.10 Pathogens found in animal manure (Nicholson et al., 2000) Pathogens Cattle Pigs Sheep Poultry E. coli O157 x x x - Sa lmonella x x x x Listeria x x NR x Campylobacter x x x x Cryptosporium x x x - Giardia x x NR - NR – not reported
Factors such as the age, diet and management of animals, as well as regional and seasonal influences affect the number of microorganisms in manures. These pathogens may also be present in dirty water, yard runoff and leachate from stored manures (Hickman et al., 2009).
3.3.4. Legislation
Legislation and voluntary initiatives for the safe use of livestock manures on land and what is covered within the legislation is summarized in Table 3.11.
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Table 3.11 Legislation/ voluntary initiatives on the use of livestock Title Measures P/L/V PTEs OCs Pathogens Control of Pollution (Silage, Regulations for the prevention of pollution from Slurry and Agricultural Fuel L I I I silage effluent, slurry, dirty water and fuel oil Oil) Regulations (1991) Commission Regulation (EC) Reduced limits on Zn and Cu in feeding stuffs L D 1334/2003 The Feeding Stuffs Sets limits on trace elements and contaminants in L D Regulations (2000) animal feedstuffs Action Programme for Limits the quantities and timing of manures that Nitrate Vulnerable Zones can be applied in NVZs. Based on nitrogen content (England and Wales) L I I I but will also limit contaminant application rates Regulations 1998 (SI and minimise pathogen transfer to water. 1998/1202) Controls on pathogens in bathing waters. May Bathing Water Directive L I have implications for manure spreading Shellfisheries Directive (EC Controls on pathogens in commercial shellfish L I Directive 91/492) beds. May have implications for manure spreading Food Safety (Fishery Products and Live Shellfish) Implements the Shellfisheries Directive L I (Hygiene) Regulations (SI 1998/994). Contains manure management notes for organic UKROFS Standards L I I I farmers Protecting our Water, Soil A code of good agricultural practice for farmers, V I I I and Air (2009) growers and land managers Managing Farm Manures for Food Safety : Guidelines for Growers to Minimise the Risks of FSA Guidance Note (2009) V I I I Microbiological Contamination of Ready to Eat Crops PTEs – potentially toxic elements; OCs – organic compounds P-Policy, L- Legislation, V-Voluntary measure D - Direct, I - Indirect. Legislation has a direct effect if its purpose is to control/limit inputs of a contaminant to soil. Indirect legislation may have implications for contaminant inputs to soil without this being its primary purpose.
The current UK recommendations for trace elements in livestock diets were established around 20 years ago (ARC, 1975, 1980, 1981, 1983) and may not reflect the higher requirements of modern livestock breeds and veterinary practices. A recent EU initiative has proposed a reduction in the levels of PTEs, especially copper and zinc, in livestock diets to try to minimize their subsequent environmental impact in land applied manures (CEC, 2000). In January 2004 a recent legislation came into force (EC, 2003) to reduce the maximum permitted levels of zinc and copper supplementation in livestock diets (ADAS, Imperial College, JBA Consulting, 2005). Previous and current maximum permitted levels of zinc and copper in livestock feeds are presented in Table 3.12.
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Table 3.12 Previous (SI 2000/2481) and current (EC, 2003) maximum permitted levels of zinc and copper in livestock feeds (mg/kg complete feed) Zinc Copper Livestock category Previous Current Previous Current Up to 16 weeks - - 175 - Up to 12 weeks - - - 170 17 weeks – 6 Pigs - - 100 25 months Other pigs - - 35 25 All pigs 250 150 - - Layer 250 150 35 25 Poultry Broiler grower 250 150 35 25 Broiler finisher 250 150 35 25 Pre-rumination - 200 - 15 Ruminants Dairy and beef cattle 250 150 35 35 Sheep 250 150 15 15
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3.4. Biowaste
3.4.1. Introduction
Biowaste is defined as biodegradable garden and park waste, food and kitchen waste from households, restaurants, caterers and retail premises, and comparable waste from food processing plants. It does not include forestry or agricultural residues, manure, sewage sludge, or other biodegradable waste such as natural textiles, paper or processed wood. It also excludes those by-products of food production that never become waste (CEC, 2008).
The total annual arising of biowaste in the EU is estimated at 76.5-102 million tonnes food and garden waste included in mixed municipal solid wastes, and up to 37 million tonnes from the food and drink industry. Biowaste is a putrescible, wet waste with two major streams – green waste from parks and gardens; and kitchen waste. The former includes usually 50-60% water and more wood (lignocelluloses); the latter contains no wood but up to 80% water (CEC, 2008).
3.4.2. Current techniques for dealing with biowaste
Separate collection schemes work well specially for green waste. The kitchen waste are often collected and treated as part of the mixed Municipal Solid Waste (MSW). Benefits of separate collection include the diversion of biodegradable waste from landfills, enhancing the calorific value of the remaining MSW, and generating a cleaner biowaste fraction, which allows the production of high quality compost and facilitates gas production (CEC, 2008).
Landfilling, although it is considered the worst option, is still the biggest MSW disposal method in the EU. The main environmental threat from biowaste is the production of methane in landfills, which accounted for 3% of total greenhouse gas emissions in the EU in 1995 (CEC, 2008).
Incineration – biowaste is usually incinerated as part of MSW and incineration can be regarded as energy recovery or as disposal.
Biological treatment includes composting and anaerobic digestion and is classified as recycling when compost/digestate is used on land. If that use is not envisaged, it is classified as pre-treatment before landfilling or incineration.
Mechanical Biological Treatment (MBT) – MBT refers to the process for treatment of mixed waste and municipal solid waste feedstocks. MBT includes mechanical sorting and separation of waste into fractions of biodegradable and non- biodegradable materials. The biodegradable fraction may be treated by different biological stabilisation processes that may include composting or anaerobic digestion. Another option is the use of the high calorific fraction of municipal solid waste to solid recovered fuel. New techniques for solid fuel recovery are currently The Food and Environment Research Agency 43
under trial (i.e. plasma treatment, gasification and pyrolysis) but are not in use in the UK or other European countries (EA, 2009).
Mechanical heat treatment (MHT) - MHT is a process that is currently used to treat clinical waste and is now being proposed to treat municipal solid waste. MHT is a process that uses thermal treatment in conjunction with mechanical processing. The aim of this treatment is to separate a mixed waste stream into a number of components that are easier to separate for recycling and recovery (Enviros, 2007). The autoclave process uses non-segregated household waste as the waste stream that is enclosed into a horizontal cylindrical autoclave. Following autoclaving, the waste is discharged and undergoes a mechanical separation. Depending on the treatment, the biodegradable fraction of municipal solid waste including paper, card, food leftovers, and other materials (e.g. nappies) are turned into a fibre like material that is currently being studied for its reuse (Papadimitriou et al., 2008). The biodegradable fraction may be treated by different biological stabilisation processes that may include composting or anaerobic digestion.
3.4.3. Treatment - Composting
3.4.3.1. Introduction
Compost is derived from biowastes that have been treated by composting. Within this section, input waste streams considered were: green wastes (i.e. garden and park waste), green/food waste (organic household waste), mixed waste and municipal solid waste (MSW), and mushroom waste.
Composting is an aerobic stabilisation process that has the potential to biodegrade relatively persistent organic compounds. In 2007/08, 5 million tonnes of source segregated waste was composted in the UK (WRAP, 2009).
Composted materials mostly comprise composts derived from green wastes and a limited amount of domestic solid waste compost. The survey of UK composting shows that in 2003/4, of the 1.97 million tonnes of wastes composted, 73% was household waste, 4% municipal non-household waste and 23% commercial wastes (Slater et al., 2005). Compost products were distributed to several markets and outlets, with agriculture the largest and the fastest growing outlet. Approximately 40% of all composted products were used in agriculture during 2003/4 (Slater et al., 2005).
Amlinger et al. (2004b) reported an extensive review on PTEs and organic compounds from composted wastes used as fertilisers. In this review, the following compost types were identified as defined by characteristics of source materials: Green compost from garden and park waste materials (grass clippings, bush and tree cuttings, leaves, flowers, etc). Green/food compost (Amlinger et al.(2004b) report this compost as biowaste compost); and
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Mixed municipal solid waste derived compost (MSWC) and the stabilised organic waste fraction from mechanical biological treatment plants (MBTC).
In this section composts were derived from:
1. Source- separated collection schemes that include:
green compost (GC); and green/food compost (G/FC).
2. Non-segregated waste that include:
mixed municipal solid waste compost (MSWC); MBT compost-like output (CLO) - in the 1970s and 1980s, significant development took place across the EU, targeted at treating unsorted municipal solid waste (MSW) by a system of mechanical and biological treatment. However, the quality of the compost-like output (CLO) from these plants was relatively poor compared to source-segregated composts (Partl and Cornander, 2006). Large quantities of physical contaminants such as glass and plastics remained in the compost along with significant quantities of metal particles, producing a compost- like material with a limited market for use. Modern plants and newly developed technologies for recycling non-segregated MSW have been built over the last 15 years. However, CLO have still very variable composition across different countries (Zmora-Nahum et al. 2007), between individual plants within the same country or region (Lasaridi et al. 2006) and seasonally (Amlinger et al. 2004b). This is not surprising in relation to MBT compost-like output as few plants have identical feedstock or plant technology (Tayibi et al. 2007). MBT CLO may be of potential benefit for soil improvement because it contains plant nutrients and stabilized organic matter (EA, 2009). However, a higher level of contamination contained in MBT CLO (relative to other types of compost produced from separately collected green waste) limits the end use for MBT outputs. MHT CLO - following mechanical heat treatment, the end fibre is still unstable and might release odours if stored and therefore the fibre needs to be stabilized through composting or anaerobic digestion. MHT CLO may be of potential benefit for soil improvement since it contains plant nutrients and organic matter. However, it can also contain a higher level of contamination since it is derived from non-source segregated MSW.
3. Mushroom compost
The amount of Spent Mushroom Compost (SMC) produced by the mushroom industry can be estimated from mushroom production data. Fresh mushroom production of 453 kg per week generates between 160 and 170 m 3 fresh SMC per year (DETR, 2000). Mushroom production in the UK fell by about 32% between 1999 and 2003, thus the production of SMC also fell. No specific data is available on the amounts of SMC used in agriculture so it has been assumed that spreading SMC to The Food and Environment Research Agency 45
agricultural land accounts for the SMC that was not used in the other 3 outlets (gardeners, local authorities and the landscape industry; Table 3.13). By this calculation, the amount of SMC used in agriculture was estimated as about 50% of SMC annually. The estimated annual production of SMC is in the range 400,000 to 600,000 t and thus represents a significant quantity compared to other industrial and biowastes applied to land.
Table 3.13 Production of mushrooms and spent mushroom compost in 1999 and 2003 (DETR, 2000; Defra, 2005b) 1999 2003 Mushroom production (t y -1) 79 439 53 345 Compost production (m 3 y-1) 556 073 – 595 792 387 415 - 400 087 Adjusted compost make (m 3 y-1)a 575 000 394 000 Outlets Gardeners 77 500 53 104 b Local authorities 14 000 9 593 b Landscape industry 190 500 130 534 b Agricultural land c 293 000 200 769 b a – amount of compost generated annually rounded to average range b- figures calculated from 1999 ratios c- assumed from difference between total amount of compost generated and that is used in other outlets
3.4.3.2. Contaminants in compost
PTEs
1. Source-segregated compost Concentrations of PTEs in composts derived from source-segregated green/food waste and green waste are presented in Tables 3.14 and 3.15, respectively.
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Table 3.14 Concentrations of PTEs in green/food compost Metal/element (mg/kg dry weight) Country Statistics Number of samples Reference Cd Cr Cu Hg Ni Pb Zn As Median 552-582 0.38 24 47 0.16 19 37 174 NA aAmlinger and Peyr, 2001 Median 0.74 31 70 0.20 23 67.5 236.5 28 5.7 aZehtner et al., 2001 Austria [mean] [0.72] [31.3] [76] [0.22] [33.3] [73.4] [237] Median 0.67 32.47 53.8 0.16 21.82 39.21 205 6.88 46 aBala, 2002 [mean] [0.7] [32.11] [56.5] [0.16] [22.27] [41.94] [219] [7.07] Belgium Median 195 0.82 22 45 0.15 12 69 229 NA aDevliegher, 2002 Denmark Mean 4 0.48 11 60 0.11 9.3 41 150 3.4 aPetersen, 2001 Finland Mean 3-6 0.6 NA NA 0.09 9.67 30.00 NA 6.00 aVuorinnen, 2002 Mean 20-28 0.9 29 96 0.6 24 86 289 Hogg et al., 2002 France Median 0.86 30.20 89.00 0.50 20.20 92.95 241.70 9.20 12-27 Charonnat et al., 2001 [mean] [1.07] [42.81] [109.77] [0.63] [25.51] [106.05] [325.66] [9.05] Median 6414-6446 0.53 25 49 0.18 16 57 196 NA aReinhold, 1998 Mean 17500 0.5 23 45 0.14 14 49 183 NA aZAS, 2002 Germany Mean 19 plants 0.45 27.2 67.9 0.23 18.5 42.7 196 NA aMarb et al., 2001 Mean 193 0.6 32 40 0.2 20 60 178 NA aSihler and Tabasaran, 1996 Median 60 0.46 NA 42.5 0.13 NA 42.5 180 4.0 aStock et al., 2002 Ireland Mean 19 0.6 15.3 46 0.4 19 31.7 138.5 NA aNí Chualáin, 2004 Median 1.08 23.1 74.9 26.2 70.7 180 Italy 127 NA NA aCentemero, 2002 [mean] [1.38] [33.1] [89.1] [26.3] [84.4] [219] Luxembourg Mean 175 0.41 32.0 38.6 0.12 15.8 48.7 218.6 7.2 (n=88) aMathieu, 2002 Median NA 0.3 17 29 0.12 7 57 157 NA Hogg et al., 2002 Mean 4 0.47 16 27 0.13 10 78 204 3.8 aDriessen and Roos, 1996 Netherlands Mean 811 0.52 20.82 36.41 0.14 10.79 63.42 189.48 3.76 aBrethouwer, 2002 Mean 172 0.4 14 30 0.13 8 56 159 5 aKoopmans, 1997 a – as cited in Amlinger et al., 2004b NA – not available
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Table 3.14 (cont.) Concentrations of PTEs in green/food compost Metal/element (mg/kg dry weight) Country Statistics Number of samples Reference Cd Cr Cu Hg Ni Pb Zn As Median 0.54 25.5 69 0.11 11.25 23.9 264 12 NA aLystad, 2002 [mean] [0.66] [24.3] [78] [0.22] [11.11] [44 .56] [331] Norway Median 0.32 14 52 0.07 10 20 197 9 plants NA Paulsrud et al., 1997 [mean] [0.36] [15] [53] [0.11] [10] [24] [210] Spain Med <1.5 27 88 0.2 23 56 202 32-56 NA aGiró, 2002 (Catalunya) [mean] [<1.1] [32] [95] [0.3] [31] [64] [214] Mean 5 plants 0.37 9.7 48 0.08 5.8 17 157 NA aLundeberg, 1998 Sweden Mean 5 0.33 9.7 27 0.05 7.9 18 93.7 NA aLundeberg, 2002 Median 0.36 22.78 47.00 0.12 15.10 44.50 162.0 88-137 NA aGolder, 1998 Switzerland [mean] [0.39] [24.45] [56.08] [0.17] [16.95] [48.06] [173.9] Mean NA 0.36 22.3 57.7 0.128 16.3 49.3 183.5 NA aCandinas et al., 1999 Median 60 0.51 16 50 0.20 18 102 186 NA Hogg et al., 2002 Mean 6 0.55 20.3 84.3 0.16 25.4 79.9 185. NA aBywater, 1998 Mean 4-15 1.0 49 47 NA NA 87 290 NA aWalker, 1997 UK ADAS, Imperial College, JBA 1Mean NA 0.6 19.8 46 0.2 17 96 182 NA Consulting, 2005 2Mean 99-102 0.62 21.4 54.5 0.20 15.6 99.7 186.1 NA WRAP, 2009 a – as cited in Amlinger et al., 2004b 1- Data from 1995-2004 from WRAP (2004) and the Composting Association. Assumes a dry solids content of 65%. 2 - Only results from PAS 100 certified green composts
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Table 3.15 Concentrations of PTEs in green compost Number of Metal/element (mg/kg dry weight) Country Statistics Reference samples Cd Cr Cu Hg Ni Pb Zn As Median 33 0.47 26 35 0.12 22 34 164 NA aAmlinger, 2000 Austria Median 0.71 24 46 0.20 19.0 58.0 236.5 14 NA aZehtner et al., 2001 [mean] [0.69] [31.9] [104] [0.25] [25] [81.3] [302] Belgium Median 229 0.70 17 32 0.12 9 44 169 NA aDevliegher, 2002 Denmark Mean 10 0.34 8.8 28 0.07 5.7 23 140 2.8 aPetersen, 2001 Finland Mean 5 0.3 NA NA 0.06 11.4 7.14 NA 1.82 aVuorinnen, 2002 Mean 336 1.4 46 51 0.5 22 87 186 NA Hogg et al., 2002 France Median 0.8 34.16 43.75 0.30 18.54 63.00 170.00 7.32 22-123 aCharonnat et al., 2001 [mean] [1.37] [45.60] [50.78] [0.52] [22.41] [87.33] [186.45] [8.94] Mean 5 plants 0.33 26.6 39.6 0.12 18.5 25.6 126 NA aMarb et al., 2001 Mean NA 0.70 27.04 32.67 0.27 17.53 60.8 167.82 NA aFricke and Vogtmann, 1993 Germany Median 82-86 0.28 28.9 36.7 0.118 13.1 31.0 141 4.61 aBeuer et al., 1997 Median 12 0.71 NA 42.0 0.16 NA 56.0 205 5.4 aStock et al., 2002 Ireland Mean 4 0.9 31.7 67.3 0.1 38.5 91.8 257.5 NA aNí Chualáin, 2004 Median 0.95 33.4 62.7 23.1 71.7 165.8 [4.5] Italy 70 NA aCentemero, 2002 [mean] [0.88] [43.4] [71.1] [29.9] [83.2] [181.5] (n=43) 6.1 Luxembourg Mean 57 0.34 23.7 32.4 0.13 12.8 44.5 164.1 aMathieu, 2002 (n=43) Median NA NA 19 28 0.1 9 49 134 NA Hogg et al., 2002 Netherlands Mean 4 0.62 25 28 0.092 14 41 144 5.1 aDriessen and Roos, 1996 Sweden Mean 6 plants 0.48 13 41 0.06 7.3 25 168 NA aLundeberg, 1998 Mean 29 0.67 20.9 51.1 0.17 18.7 118.2 198 NA aBywater, 1998 UK Mean 4-15 0.075 20 37 NA NA 87 214 NA aWalker, 1997 1Mean 22-24 0.8 23.5 54.5 0.35 12.6 115.5 188.9 NA WRAP, 2009 a – as cited in Amlinger et al., 2004b 1 – Only results from PAS 100 certified green composts
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Comparisons between metal levels in G/FC and GC showed that Cu, Pb, Zn and Hg had lower concentrations in GC than in G/FC (Breuer et al., 1997 as cited in Amlinger et al., 2004b). For Cd, Cr and Ni no difference was identified. Comparison between G/FC and GC for several countries, Amlinger et al (2004b) concluded that: Concentration levels for PTEs in G/FC tend to increase more significantly than levels for PTEs in GC, which might be partly due to less effective source separation schemes in some cases. The difference is more significant in countries that are in the starting phase of separate collection systems. Countries that are introducing separate collection systems for green and household waste (UK, France, Spain and Italy) generally show higher concentrations of PTEs in composts when compared to countries with an established source separation in place (The Netherlands, Denmark, Austria). In G/FC the difference in metal concentrations decreases in the sequence: Cu>Cd, Ni, Pb, Zn>Cr, Hg. In GC the difference in metal concentrations decreases in the sequence: Pb, Cd, Cr>Cu>Hg, Ni, Zn. The effect for Pb might be due to a higher level of attention paid to green waste coming from roadsides and high traffic areas in most countries with “mature” schemes.
In a recent study in the UK from WRAP (2009) there was almost no difference in heavy metal content from GC and G/FC.
2. Non-source segregated composts
Concentrations for PTEs in mixed municipal solid waste compost, and in MBT CLO are presented in Tables 3.16 and 3.17, respectively.
In Table 3.18, the average, minimum and maximum concentrations of metals detected in the MHT CLO and the potential average metal content for compost or digestate, assuming 50% dry matter reduction during biological treatment, are presented.
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Table 3.16 Concentrations of PTEs in municipal solid waste composts Metal/element (mg/kg dry weight) Reference Number of Country Statistics (as cited in Amlinger et samples Cd Cr Cu Hg Ni Pb Zn As al., 2004b) Mean 32 5.0 98 333 - 80 728 1,450 NA Lechner, 1989 Austria Mean 25 3.3 85 455 2.5 71 461 1,187 NA Amlinger et al., 1990 Median 1.66 109.82 153.00 1.50 44.35 313.75 559.50 France 9-56 [12.69] Charonnat et al., 2001 [mean] [4.62] [126.34] [164.37] [1.64] [60.35] [325.92] [554.28] Mean 128 3.0 164 330 2.3 87.6 588 915 NA Ulken, 1987 Germany mean NA 5.5 71 274 2.4 45 513 1,570 NA LAGA, 1985 Ireland Mean 6 2.5 106 454 0.4 102 274 775 NA Ní Chualáin, 2004 Median 2.90 72.7 114.0 35.8 385.0 703 Italy 14 NA NA Centemero, 2002 [mean] [2.80] [78.9] [177.8] [41.8] [365.7] [1,025] Mean 49-68 1.66 198 400 1.5 61 326 820 NA Canet et al., 2000 Spain Means of 2 plants NA 1 66/71 144/336 NA 73/104 185/213 283/533 NA Giró Fontanals, 1998
Median 3 80 217 1 65 428 454 (Catalunya) 3-207 NA Giró, 2002 [mean] [4.1] [109] [431] [1] [71] [636] [647] Mean 18 (1 plant) 0.265 9.74 58.15 0.105 21.28 121.0 199.2 NA Anderson, 2002 UK mean 4-15 5.5 71 274 NA NA 513 1,510 NA Walker, 1997
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Table 3.17 Concentrations of PTEs in mechanical biological treatment compost-like outputs Metal/element (mg/kg dry weight) Reference Number of Country Statistics (as cited in Amlinger samples Cd Cr Cu Hg Ni Pb Zn As et al., 2004b) Range 0.7 -6.1 24 -344 161 -500 0.1 -4.1 18 -253 64 -963 235 -990 NA Austria 9 Amlinger et al., 2000 Median 2.7 209 247 1.3 149 224 769 NA France mean 100 4.5 122 162 1.6 60 319 542 NA Hogg et al., 2002 Range 0.22 -1.87 3.7 -50.6 25.3 -306 0.001 -0.93 9.6 -93.9 73.4 -683 130 -560 NA UK 16 (1 plant) Anderson, 2002 Median 0.41 15.8 91.1 0.15 31.0 166.8 286 NA
Table 3.18 Concentrations of PTEs in mechanical heat treatment compost-like outputs (CalRecovery, 2007) Fibre metal content Metals *Potential average content for fibre compost or digestate Mean [min; max] Cd 1.8 [0.4 ; 6.5] 3.6 Cr 85.4 [20; 265] 170.8 Cu 68.2 [34; 82] 136.4 Pb 99.9 [38; 330] 199.8 Hg <0.06 [<0.01; 0.14] <0.12 Ni 21.1 [10; 58] 42.2 Zn 389.6 [150; 720] 779.2 * assuming a 50% dry matter reduction during biological treatment
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A study carried out for DG Environment in 2004 showed that the levels of metals from material derived from MBT plants (MBT CLO) can be two to 10 times greater than those present in compost derived from source-separated green waste (Amlinger et al. 2004b). Older and more recent data on concentrations of PTEs in MSWC and stabilized material from mechanical biological treatment, modern pre- treatment techniques and general source segregation for paper, glass, metals and hazardous waste are still no guarantee of a significant reduction of heavy metal levels (Amlinger et al. 2004b).
In Table 3.19 the potential average metal content of the MHT CLO was compared to mean metal contents from compost derived from non-segregated municipal solid waste following mechanical and biological treatment (Amlinger et al., 2004b). With the exception of Hg that is detected in the fibre at much lower concentrations, all other metal concentrations are within the range of metal content in compost derived from municipal solid waste. Cd and Cr in the potential fibre-based compost are found to be at the upper range levels, whereas Cu, Pb, Ni are closer to the lower range concentrations. Zn content is in the middle of the range and Hg is below the lower range. Therefore, treatment of municipal solid waste by autoclaving seems to have greater potential than the use of mechanical and biological treatment for the production of quality material (CalRecovery, 2007).
Table 3.19 Average metal content in potential MHT CLO and non-segregated municipal solid waste compost. Average metal content (mg/kg dm) Compost Cd Cr Cu Pb Hg Ni Zn Potential metal content in 3.6 170.8 136.4 199.8 <0.12 42.2 779.2 MHT CLO MSW compost 1.7-5.0 70-209 114-522 181-720 1.3-2.4 30-149 283-1570 (Amlinger et al., 2004b)
Mixtures of feedstock materials for composting
Different feedstocks might also be mixed to derive composts. Concentrations of potential toxic elements in compost mixtures are presented in Table 3.20.
Further potentially toxic elements
Concentrations in composts of other potentially toxic elements are presented in Table 3.21.
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Table 3.20 Heavy metal concentrations in compost of mixtures Metal/element (mg/kg dry weight) Country Statistics Mixture n Reference Cd Cr Cu Hg Ni Pb Zn As Belgium Median *Humotex 9 0.6 25 36 0.1 12 63 199 N A aDevliegher, 2002 Median 1.00 34.35 106.00 0.70 24.21 52.63 316.85 France Compost of mixtures 12-14 NA Charonnat et al., 2001 [mean] [1.02] [48.44] [114.10] [0.64] [28.73] [54.08] [361.06] Germany mean Mowed material from roadside 46 0.9 70 65 0.3 47 142 215 NA aSihler and Tabasaran, 1993 Ireland mean Composted fish waste 5 1.0 43 33.3 0.1 8.7 8.9 67.3 NA aNí Chualáin, 2004 Median 0.92 12.7 44.0 12.7 11.2 284 Butchery-waste+greenwaste 16 NA NA aCentemero, 2002 [mean] [0.94] [13.4] [47.8] [16.6] [13.9] [296] Italy Median Growing media for gardening 0.86 33.6 63.8 25.2 27.8 20. 61 NA NA aCentemero, 2002 [mean] uses (with compost) [1.08] [33.7] [60.8] [27.1] [47.5] [241] Mean Waste of bulbs 4 0.24 9.5 9.5 0.17 7.0 21 53 2.3 aDriessen and Roos, 1996 Mean Mowed material from roadside 4 0.38 18 22 0.12 9.9 49 122 3.7 aDriessen and Roos, 1996 Mean Horticultural waste 4 0.6 20 41 0.24 13 68 266 2.1 aDriessen and Roos, 1996 Mixture of horse manure, straw, Netherlands Mean peat, plaster. It’s the final product 4 0.35 12 44 0.044 9.6 19 174 0.9 aDriessen and Roos, 1996 (substract) of mushrooms Mean Topsoil of heather (sod) natural 4 0.43 4.7 8.4 0.072 7.0 42 27 2.4 aDriessen and Roos, 1996 area in the Netherlands Mean MXD-composted source segregated material of mixed or 14 0.67 42.4 76.9 0.25 16.4 103.9 267 NA aBywater, 1998 UK undetermined origin Mean Composted commercial single- 3 0.37 5.5 31.6 17.8 0.05 5.3 117 NA aBywater, 1998 substrate matter a – as cited in Amlinger et al., 2004b *Humotex is the product made from anaerobic digestion and consequent aerobic stabilisation of biowaste
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Table 3.21 Concentrations of further potential toxic elements in compost Compost Metal/element (mg/kg dry weight) Country Statistics n Reference type Al As B Be Co Fe Mn Mo Na Sb Se Sn Tl V Median 11,541 5.7 8.2 0.5 7.2 643 2.2 1.2 <5 <2.5 26 aZethner et NA 15-42 NA NA NA [mean] [11,880] [6.4] [9.5] [0.5] [9.3] [830] [2 .7] [1.8] [<5] [<2.5] [29] al., 2000 Austria Median 11,794 6.88 6.55 14,418 1.97 25.5 NA 65 NA NA NA NA NA NA NA NA aBala, 2002 [mean] [11,914] [7.07] [7.26] [15,299] [1.89] [26.8] Median OHWC 6,083 3.41 20.5 5.29 9,612 401 2958 0.17 0.072 aBreuer et 3-196 NA NA NA NA NA [mean] [6,485] [3.65] [21.5] [5.49] [9,811] [400] [3008] [0.17] [0.074] al., 1997 Germany Median 6,194 4.61 18.5 6.4 11,358 487 285 0.14 0.099 aBreuer et GC 4-86 NA NA NA NA NA [mean] [6,239] [4.74] [20.5] [6.4] [11.991] [495] [319] [0.15] [0.092] al., 1997 Median 9.2 11,640 0.5 Charonnat OHWC 9-14 NA NA NA NA [430] [1.81] NA NA NA NA NA [mean] [9.05] [10,350] [0.78] et al., 2001 France Median 7.32 6,600 262 1.6 0.36 Charonnat GC 15-58 NA NA NA NA NA NA NA NA NA [mean] [8.94] [8,140] [293] [3.15] [1.14] et al., 2001 OHWC including Range of 10 2.17- 0.13- 0.80- 0.70- 0.50- 18.20- aBecaloni et agro- NA NA NA NA NA NA NA NA means plants 14.25 0.50 4.50 50.00 1.50 96.00 al., (o.J) industrial Italy sludges
Range of 3 7.60- 0.21- 0.8- 1.03- 0.88- 21.13- aBecaloni et GC NA NA NA NA NA NA NA NA means plants 12.51 0.31 1.60 6.00 1.50 66.50 al., (o.J)
a – as cited in Amlinger et al., 2004b
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3.4.3.3. Organic compounds
General
Limits for organic contaminants in compost do not exist. This situation is especially relevant for compost-like outputs, where recent evidence suggests that too little effort has been invested in assessing risks from organic compounds, such as pharmaceuticals, fragrances, surfactants, and ingredients in household cleaning products, likely to be found in waste streams destined for land (Eriksson et al . 2008).
Fungicides, disinfectants and insecticides are used in mushroom production. Therefore, the use of spent mushroom compost in agriculture, gardening and landscaping means that any pesticide residues will be added to soils.
Pesticides of concern that have been frequently detected in composts include: carbaryl, atrazine, chlordane, 2.4-D, dieldrin, chlorpyrifos, diazinon, malathion, and others (Swedish EPA, 1997). Degradation-resistant herbicides have been identified as a source of plant phytotoxicity of composts, even at very low concentrations and this raises the possibility that all composts may be required to pass a bioassay to assure absence of potential to harm plants (Hogg et al ., 2002). Certain herbicides, such as chlorpyralid and picloram, are very persistent to degradation and research suggests that they may decompose slower in compost than in natural soils (Hogg et al., 2002).
Concentrations
In the review from Amlinger et al. (2004b), selection criteria for the evaluation of organic contaminants were set based on their potential occurrence in compost, the availability of published data, and knowledge of physicochemical properties and feasibility of chemical analysis. The compounds considered were: PCBs; PPCDD/Fs; PAHs; Chlorinated pesticides and adsorbable organic halogen (AOX) (aldrin, biphenyl, o-phenylphenol chlordane, dieldrin, endrin, heptachlor, DDT [1,1,1-trichlor-2,2-bis(p-chlorphenyl)ethan], lindane, HCH-isomers [hexachlorcyclohexan], hexachloro-benzene, hexachlorobenzol, hepta- chlor, pentachlorophenol, pyrethroids, thiabendazole); LAS; NPE; Di (2-ethylhexyl) phthalate (DEHP); Butylbenzyl phthalate (BBP); Dibutyl phthalate (DBP).
Concentrations of PCBs, PAHs and PCDD/Fs in composts are presented in Tables 3.22, 3.23 and 3.24, respectively.
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Table 3.22 Concentrations of PAHs in composts in μg/kg dry weight (unless otherwise stated) Compost type Reference Country PAHs Statistics G/FC GC MSWC ∑ 15 US EPA PAHs aKrauss, 1994 Germany Mean 2175 (n=-26) 2655 (n=4) NA (without acenaphtylene) Berset and Holzer, 1995 Switzerland ∑ 16 US EPA PAHs Mean 2698 (n=2) 2492 (n=1) NA aHund et al., 199 9 Germany ∑ 16 US EPA PAHs Mean 2786 (n=7) 3309 (n=1) NA ∑ 15 US EPA PAHs aZethner et al., 2000 Austria Mean 965 (n=29) 774 (n=13) NA (without naphthalene) ∑ 15 US EPA PAHs Vergé-Leviel, 2001 France Mean 3200 (n=3) 1670 (n=1) NA (without acenaphtylene) Houot et al., 2002 France ∑ 16 US EPA PAHs Mean 2779 (n=1) NA NA aKuhn and Arnet, 2003 Switzerland ∑ 16 US EPA PAHs Mean 4119 (n=4) NA NA bKumer, 1992 NA ∑ 16 PAHs Mean 0.8-1.04 mg kg -1 dm NA 4.41 mg kg -1 dm bFricke and Vogtmann, 1993 NA ∑ 6 PAHs Mean 1707 1560 NA bSchwardorf et al., 1996 NA NA Median 3.9 mg kg -1 dm 3.8 mg kg -1 dm NA bBreuer et al., 1997 NA ∑ 16 PAHs Median 3584 3586 NA bAmlinger, 1997 (sp323) NA NA Mean 1.2 mg kg -1 dm (n=6) 1.7 mg kg -1 dm (n=3) NA bZethner et al., 2001 Austria NA Median 962 (n=42 plants) NA bMarb et al., 2001 Germany ∑ 16 PAHs Mean 4573 (n=15) 2674 (n=5) NA bStock and Friedrich, 2001 NA NA Median 1.9 mg kg -1 dm (n=30) NA bStock et al., 2002 NA ∑ 16 US EPA PAHs Median 2.35 mg kg -1 dm (n=60) 2.16 mg kg -1 dm (n=12) NA 1.4-11.19 mg kg -1 dm 1.51-1.68 mg kg -1 dm 1.47-4.99 mg kg -1 dm Houot et al., 2003 NA NA Range (n=4) (n=2) (n=5) a – as cited in Brändli et al., 2005 b- as cited in Amlinger et al., 2004b
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Table 3.23 Concentrations of PCBs in composts in μg/kg dry weight (unless otherwise stated) Compost type Reference Country PCBs Statistics G/FC GC MSWC Brändli et al., 2007a Switzerland ∑ 7 PCBs Median NA 26 (31 plants) NA Berset and Holzer, 1995 Switzerland ∑ 6 PCBs Mean 69.8 (n=2) 30.6 (n=1) NA aAldag and Bischoff, 1995 Germany ∑ 6 PCBs Mean 52.5 (n=8) 61.0 (n=6) NA aHund et al., 1999 Germany ∑ 6 PCBs Mean 41.8 (n=7) 41.7 (n=1) NA Vergé-Leviel, 2001 France ∑ 6 PCBs Mean 85.0 (n=3) 59.0 (n=1) NA 0.44 mg kg -1 dm 0.24 mg kg -1 dm aKumer, 1992 NA ∑ 6 PCBs Mean 1.68 mg kg -1 dm (3 plants) (5 plants) 0.150-0.860 mg kg -1 dm 0.030-0.480 mg kg -1 dm 0.730-1.680 mg kg -1 dm bKrauβ et al., 1992 NA ∑ 6 PCBs Range of means (6 plants) (9 plants) (4 plants) bKrauβ et al., 1992 NA ∑ 6 PCBs Mean 104 45 NA bFricke et al., 1991 NA ∑ 6 PCBs Median 0.23 mg kg -1 dm 0.15 mg kg -1 dm NA bFricke and Vogtmann, 1993 NA ∑ 6 PCBs Mean 0.26 mg kg -1 dm 178 1,493 bSchwardorf et al, 1996 NA ∑ 6 PCBs Median 0.08 mg kg -1 dm 0.07 mg kg -1 dm NA bBreuer et al., 1997 NA ∑ 6 PCBs Median 56 51 NA 0.03 mg kg -1 dm 0.03 mg kg -1 dm bAmlinger (1997[sp277] NA ∑ 6 PCBs Mean NA (n=6) (n=3) bZethner et al., 2000 Austria ∑ 6 PCBs Median 11.6 (n=29) 7.2 (n=13) NA bMarb et al., 2001 Germany ∑ 6 PCBs Mean 43.0 (n=15) 29.0 (n=5) NA bStock and Friedrich, 2001 NA ∑ 6 PCBs Median 25 (n=30) NA NA bStock et al., 2002 NA ∑ 6 PCBs Mean 9.79 (n=60) 11.08 (n=2) NA 41-293 Houot et al., 2003 NA ∑ 6 PCBs Range 34-104 (n=4) 19-66 (n=2) (n=5) aTimmermann et al., 2003 NA ∑ 6 PCBs Mean 51 (n=30) NA NA bKrauss, 1994 Germany ∑ 6 PCBs Mean 32.4 (n=33) 28.0 (n=20) NA bBayerisches Landesamt fur Germany ∑ 6 PCBs Mean 32.4 (n=33) 75.9 (n=27) NA Umweltschultz, 1995 a – as cited in Brändli et al., 2005 b- as cited in Amlinger et al., 2004b
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Table 3.24 Concentrations of PCDD/Fs in composts in ng [I-TEQ]/kg dry weight (unless otherwise stated) Compost type Reference Country PCDD/Fs Statistics G/FC GC MSWC aKummer, 1990 Germany ∑ 17 PCDD/Fs Mean 10.6 (n=8) 12.5 (n=9) NA aHarrad et al., 2001 USA ∑ tetra- to octa-PCDD/Fs Mean NA 21423 ng/kg dw (n=13) NA aMalloy et al., 1993 USA ∑ tetra- to octa-PCDD/Fs Mean NA 21427 ng/kg dw (n=7) NA aKrauss, 1994 Germany ∑ 17 PCDD/Fs Mean 9.9 (n=-33) 5.2 (n=20) NA aAldag and Bischoff, 1995 Germany ∑ 17 PCDD/Fs Mean 5.5 (n=8) 12.0 (n=5) NA bBayerisches Landesamt fur Germany ∑ 17 PCDD/Fs Mean 11.4 (n=28) 11.4 (n=8) NA Umweltschultz, 1995 aKummer, 1996 Germany ∑ 17 PCDD/Fs Mean 14.8 (n=1) 11.0 (n=1) NA aZethner et al., 2000 Austria ∑ 17 PCDD/Fs Mean 6.9 (n=29) 5.1 (n=13) NA bMarb et al., 2001 Germany ∑ 17 PCDD/Fs Mean 10.7 (n=15) 9.3 (n=5) NA 9.6 or 894 ng/kg dw 13.2 or 894 ng/kg dw bWeiss, 2002 Germany ∑ 17 PCDD/Fs Mean NA (n=3) (n=2) a – as cited in Brändli et al., 2005 b- as cited in Amlinger et al., 2004b
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PCBs have been banned from industrial processes and therefore their occurrence in the environment is decreasing. Generally, PCBs were detected in higher concentrations in composts from urban areas. Some, but not all, studies showed higher concentrations in G/FC than in GC. PCB content in compost from MSW was around 50 to 100-fold higher than that found in compost from source separated G/FC and GC. Input of PCBs to soil from compost was less than from atmospheric deposition rates (Amlinger et al., 2004b).
Concentrations of PCDD/Fs in composts are dependent on the background concentrations in the soil (when soil is added to speed the composting process) and the source material following diffuse emissions in the catchment area of the composting plant. No clear difference could be observed between rural and urban areas. Several studies showed lower amounts of PCDD/Fs in GC than in G/FC (Krauss, (1994), Kummer (1996) and Zehtner et al. (2000) as cited in Amlinger et al., 2004b). PCDD/Fs content in composts from mixed municipal solid waste was generally 50 to 100 times higher than in compost from source-segregated bio and green waste. In general, PCDD/Fs tend to concentrate during degradation because of mass loss during mineralization of organic matter. Therefore, lower concentrations of PCDD/Fs were observed in biowaste feedstocks than in the finished composts.
Higher concentrations of PAHs are assumed to be found in urban areas. Only a slight trend indicated that concentrations of PAHs in G/FC were higher than in green compost and PAH content in composts from mixed municipal solid waste were generally 1 to 10 times higher than in compost from source-segregated biowaste.
Overall, the review from Amlinger et al. (2004b) concluded that concentrations of PCBs, PCDD/Fs and PAHs in biowaste compost were similar to soils background concentrations. Therefore, it was concluded that threshold limits for these compounds are not required for the safe use of compost derived from source segregated organic waste materials. This was not the case for mixed waste compost, where higher concentrations of these organic compounds have been reported. Amlinger et al. (2004b) recommended the monitoring of these compounds when mixed waste compost is used for land application, and that the use of this compost should be limited to non-food areas such as land reclamation of Brownfield sites, surface restoration on landfill sites, or on noise protecting structures besides roads and railways. Maximum concentrations of PCDD/Fs in compost from mixed waste collection systems samples were still below the permitted levels for these compounds in sewage sludge.
In the provinces of Quebec and Nova Scotia, Canada, concentrations of dioxins/furans, dioxin-like PCBs and PAHs were measured in 14 composts (Groeneveld and Hébert, 2005). Dioxins and furans had low concentrations, with an average of 9.7 ng I-TEQ kg -1 DS, and a range of 1.0 to 31 ng I-TEQ kg -1. Dioxins/furans in all the compost samples tested were between 10 and 300 times lower than the risk based limit of 300 ng TEQ DFP (TEQDFP-WHO98, sum of dioxins (D), furans (F) and dioxin-like compounds (P) originally proposed by US EPA). On average, dioxin- like PCBs represented less than 20% of the TEQ DFP total. PAH content was generally
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low, with 96% of all analyses with concentrations below the limits of detection or quantification. Groeneveld and Hébert (2005) concluded that there was no justification to include dioxins/furans, PCBs or PAHs as parameters in compost quality criteria.
Brändli et al. (2005) reviewed available data on persistent organic pollutants (POPs) in composts and main feedstocks from more than 60 reports. Median concentrations of the sum of 16 PAHs, the sum of 6 PCBs and the sum of 17 PCDD/Fs were higher in green waste than in organic household and kitchen waste. In foliage, persistent organic pollutants concentrations were up to 12 times higher than in other feedstock materials. In contrast, compost from organic household waste and green waste contained similar amounts of PAHs, PCBs and PCDD/Fs. During composting, concentrations of three ring PAHs decreased, whereas five- to six-ring PAHs and PCBs increased due to mass reduction during composting. PCDD/Fs accumulated by up to a factor of 14. As expected, urban feedstock and compost had higher concentrations of POPs than rural material. Highest concentrations of POPs were usually observed in summer samples, in accordance to what have been generally observed for PCBs, but not for PAHs and PCDD/Fs. Median concentrations of POPs in compost were greater than for arable soils but were within the range of many urban soils.
Overall, of the seven types of feedstocks investigated, foliage contained the highest concentrations of PAHs, PCBs and PCDD/Fs. Bark, shrub, clippings and grass showed the lowest concentrations of POPs, followed by organic household waste and green waste. The higher concentrations observed in foliage and green waste might be explained by the efficient filter characteristics of these materials. Similar concentrations of POPs were observed for green/food waste and green waste composts; this can be attributed to the fact that food waste is often blended with green waste for aerobic composting. PAHs concentrations in feedstocks and compost were similar, whereas for PCBs concentrations in compost were at the higher end of feedstock concentrations, suggesting that degradation/volatilization of the lower molecular weight PAH congeners occurs, whereas it was not apparent for the heavier molecular weight PAHs, PCBs or PCDD/Fs. The increase of PCDD/Fs concentrations in compost when compared to feedstock materials was larger than could be accounted for by the mass balance and loss of volatile solids during composting, suggesting that for the main POP classes investigated, atmospheric deposition may be a relevant input source for these compounds.
The majority of chlorinated pesticides are banned in the EU. A considerable number have been analysed in compost but they are rarely detected and only in very small amounts (Amlinger et al., 2004b; Brändli et al., 2005). In general, G/FC have larger concentrations of these compounds than green compost. Organochlorine pesticides, pyrethroids and thiabendazole were close to the detection limits and below permitted values for fertilizer regulations (Amlinger et al., 2004b). The AOX and chlorinated pesticide groups comprise a wide range of compounds with different properties and thus behaviour during composting. Composting generally decreases concentrations for most of these compounds. The exception is for compounds used
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for wood preservation that given their high persistence and toxicity, should be excluded from the production of compost products or any recycling to land. Biphenyl, which is a fungicide widely used in citrus production, was detected in all composts and Brändli et al. (2005) suggested that the main route of entry is via organic household wastes. Other citrus fungicides such as o-phenylphenol and thiabendazole were also detected in compost, whereas pesticides such as cyfluthrin, deltamethrin and fenpropathrin were rarely measured and reported.
LAS, NPE, DEHP, and PBDE are rapidly degraded under aerobic conditions during composting. Very low concentrations have been reported in the literature reviewed by Amlinger et al. (2004b). Therefore, there is no evidence for a need for limit values. Median concentration of DEHP in compost was 300 μg/kg dry weight (Brändli et al., 2005). DEHP content in compost containing green/food waste was higher than in GC, which indicated a potentially larger plastic content in organic household waste. Polybrominated diphenylethers (PBDEs) are used as flame retardants and are detected at increasing concentrations in the environment and were detected in compost at 12.2 μg/kg dry weight (Brändli et al., 2005).
Mushroom compost
In mushroom production, fungicides, disinfectants and insecticides are used (ADAS, Imperial College, JBA Consulting, 2005). Spent mushroom compost may be applied to land and is marketed for horticultural use, which implies that any pesticide residues will also be added to soils. Pesticides are applied as sprays or drenches (43%) or in irrigation systems (47%) with aerosol and wash-down methods accounting for 5% each. Insecticides and disinfectants are used between crops and thus directly applied to the compost and surrounding trays, boxes and ancillary equipment. Pesticides are used in all stages of crop production. Mushrooms are present on the compost surface for only about two weeks of the crop production cycle. On average, crops receive two treatments of disinfectant, one of insecticide and one of fungicide during each crop cycle (CSL, 2004). In the UK, the use of pesticides by the mushroom industry is shown in Table 3.25.
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Table 3.25 Use of pesticides on mushrooms grown in Great Britain in 2003 (CSL, 2004) Treated square metres Kg active substance used Disinfectant Formaldehyde 459 883 4 040 Sodium hypochlorite 3 080 175 893 All disinfectants 3 540 058 4 933 Fungicides Carbendazim 353 647 426 Prochloraz 3 832 452 1 775 Pyrifenox 142,084 142 All fungicides 4 328 183 2 3 43 Insecticides Bendiocarb 357 958 28 Diflubenzuron 338 653 298 Other insecticides 23 485 1 All insecticides 720 096 32 6 All registered pesticides 1 8 667 543 7 603 Biological control agents Steinernema feltiae 675 569 NA Heterorhabditis megid as 5 695 NA All biological agents 681 264 NA All non -registered substances 2 5 668 350 152 039 NA – not available 1- Registered pesticides refers to those active substances and formulations approved under the Control of Pesticides Regulations (COPR) 1986 as amended and the Plant Protection Products Regulations (PPPR) 2003 2- Non-registered substances do not infer non-approved use of pesticides but refers to the use of chemicals and biological agents that do not come under COPR (1986) or PPPR (2003).
Mushroom production fell by about 30% since 1999 and over the same period the amount of pesticide active ingredient decreased by 68%. This accounted for by a fall in insecticides use of 82%, disinfectants by 74% and fungicides by 26%, due to the withdrawal of the approval of several active ingredients (Chemical Regulation Directorate), with no replacement alternative compound approved for these uses. In both 1999 and 2003 surveys there was no record of the use of compost sterilants (CSL, 2004) and the use of organophosphates and organochlorines is also absent from the 2003 survey data.
In conclusion, SMC is likely to contain pesticides and residues of other chemicals but the range of chemicals used seems to have decreased in recent years due to the withdrawal of pesticides previously approved for use in mushroom production.
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3.4.3.4. Pathogens in composts
The composting process involves the creation of high temperatures within a pile that would usually be enough to kill most enteric pathogens if correctly managed (ADAS, Imperial College, JBA Consulting, 2005).
In May 2000, the Composting Association provided the industry with standards for composts and these formed the Publicly Available Specification for Composted Materials (PAS 100) published by the British Standards Institution (BSI, 2005). The composts have to be tested for the human pathogen indicator species Salmonella and E. coli. To comply with PAS100, which is a voluntary standard, Salmonella sp must be absent in a 25 g sample and the E. coli content must be below 1000 cfu/g. Compliance with the industry standards and specifications is voluntary (ADAS, Imperial College, JBA Consulting, 2005).
3.4.4. Treatment – Anaerobic digestion
3.4.4.1. Introduction
Digestate is derived from biowastes that have been treated by anaerobic digestion. Anaerobic digestion is a process that breaks down organic matter under anaerobic conditions. This process can be used to treat a range of wastes including sewage sludge, organic farm wastes, municipal solid wastes, green wastes and organic industrial and commercial wastes. Before being digested, the feedstock needs pre- treatment. The purpose of this treatment is to mix different feedstocks, add water, or to remove undesirable materials such as plastics and glass to produce better digestate quality and to allow a more efficient digestion.
The digestion process takes place in digesters, which have different characteristics and properties and accordingly are more or less suitable for a specific feedstock. At present there are more mesophilic (35˚C) than thermophilic digesters (55˚C).
The by-products of the anaerobic digestion process are biogas and digestate. Biogas can be upgraded by removing carbon dioxide and the water vapour and then used in a CHP (Combined Heat and Power) unit to produce electricity and heat. The digestate is composed of whole digestate, separated liquor and separated fibre and can be used as a fertilizer or further processed into compost to increase quality. This type of biological treatment has become well established in some EU countries but currently under-utilised in the UK (BSI, 2008). Anaerobic digestion is used for the treatment of: Liquids with low dry matter (sugar processing waters) Liquids with a higher organic matter (slurry, sewage and food processing sludge) Solid biodegradable materials (food waste, crops, solid manure)
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3.4.4.2. Contaminants PTEs
Heavy metal concentrations in anaerobic digested samples derived from food wastes for the UK are summarised in Table 3.26.
Table 3.26 Concentrations of PTEs in digestate from the UK (ADAS, 2009) Metal Concentration in mg/kg DM Cd 1.5 Cr 15.3 Cu 60.6 Hg ND Ni 11.0 Pb 80.3 Zn 291.4 As ND
Organic compounds
Very little is known on concentrations of organic compounds in digestates. Data was not found for anaerobic digestates from the UK but was found for Swiss digestates from kitchen or green waste (Kupper et al. 2006). These data are shown on Table 3.27.
Table 3.27 Concentrations of organic compounds in Swiss digestates in µg/kg dry weight (dw) unless otherwise stated (Kupper et al., 2006) Organic compound Mean Median n ∑ 15 PAHs 5925 4202 13 ∑ 7 PCBs 32 31 13 4.1 ng WHO -TEQ/Kg 3.7 ng WHO -TEQ/Kg aDL PCBs 5 dw dw PCDD/Fs 3.2 ng I -TEQ/Kg dw 2.7 ng I -TEQ/Kg dw 5 PBDE (pentaBDE) 2.7 1.9 5 PBDE (octaBDE) 0.3 0.3 5 PBDE (decaBDE) 13.8 10.0 5 Hexabromocyclododecane 187 174 5 Tetrabromobisphenol A 0.9 1.0 5 ∑ perfluorinated sulfonates 3.9 2.3 5 ∑ perfluorinated carboxilates 4.1 3.1 5 ∑ fluorooctane sulphonamides 0.3 0.3 5 and -sulfonamidoethanols bPesticides 114 78 5 Pht halates - DEHP 1140 1140 2 Pht halates - DBP ND ND 2 NP ND ND 2 WHO- World health Organization; I – international; TEQ- toxicity equivalents) a- Dioxin Like PCBs b- ∑ of 271 compounds (86 fungicides, 86 herbicides, 92 insecticides, 5 acaricides, 1 nematicide, 1 plant growth regulator) The Food and Environment Research Agency 65
Pathogens
Temperature is the most important factor when considering the reduction of pathogens during anaerobic digestion (Sahlström, 2003). Experimental investigations demonstrate that Escherichia coli and Salmonella spp. are not damaged by mesophilic temperatures, whereas rapid inactivation occurs by thermophilic digestion (Smith et al., 2005). On the other hand, in another study, mesophilic anaerobic digestion has been shown to reduce levels of pathogens in animal waste (Kearney et al., 2008).
A draft has been prepared for a Publicly Available Specification (PAS) for whole digestate, separated liquor and separated fibre derived from the anaerobic digestion of source-segregated biodegradable materials (BSI, 2008). The purpose of this PAS is to ensure that digested materials are made using suitable input materials and effectively processed by anaerobic digestion. As for composted materials, digested materials are proposed to be tested for the human pathogen indicator species Salmonella spp and E. coli.
3.4.5. Legislation
Legislation for the application of compost or digestate to soils is similar since currently there is not any legislation on how to deal with biowastes (Table 3.28). However, in the UK there is a Publicly Available Specification (PAS) for both compost (BSI, 2005) and digestate (BSI, 2008) to ensure the production of quality materials from both these treatment processes. However, these PAS are voluntary.
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Table 3.28 Legislation/ voluntary initiatives on the use of compost/digestate Title Measures P/L/V PTEs OCs Pathogens Defra to encourage the development of quality Waste Strategy 2000 standards for compost. WRAP to take measures to P I I I increase composting. Sets targets to reduce biodegradable wastes going Landfill Directive to landfill (and hence increase amounts L I I I (EC/31/1999) composted and reused). Animal By-Products Requires treatment of food waste (in response to L I (Amendment) Order (2001) foot and mouth outbreak). Biological Treatment of Not applied. ? D I Biowaste, 2001 – 2nd draft Specification for BSI Standards for composts including heavy Composted V D I D metals, Salmonella and E. coli. Materials (PAS100 : 2005) Specification for BSI Standards for digestate including heavy Anaerobically Digested V D I D metals, Salmonella and E. coli. Materials (PAS 110 : 2008) Decision of 28 August 2001 (2001/688/EC). Ecological criteria for the award of Products shall not contain bark that has been the Community eco-label treated with pesticides. to soil improvers and growing media PTEs – potentially toxic elements; OCs – organic compounds P-Policy, L- Legislation, V-Voluntary measure D - Direct, I - Indirect . Legislation has a direct effect if its purpose is to control/limit inputs of a contaminant to soil. Indirect legislation may have implications for contaminant inputs to soil without this being its primary purpose.
Limits Limits for contaminants in composts are available from PAS 100:2005 and are presented in Table 3.29. There are no limits for organic contaminants in composts. In Annex III of the 2001 Biowaste Working Document (EC, 2001) specific limit values for two grades of ‘compost’ were proposed (Class 1 and 2) and also for ‘stabilised biowaste’ materials, a term used to cover MBT outputs and similar materials. The two classes of compost/digestate from source-separated feedstock were considered suitable for land application on land growing food crops. However, the stabilized biowaste was considered unsuitable for use on pasture or food crops, but suitable for landscape restoration, road construction, etc.
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Table 3.29 Limits for contaminants for compost (class 1 and 2), digestate and stabilised biowaste UK EC, 2001 (proposed) Digestate Compost Normal/exceptional upper limit PAS 100:2005 Class 2 Stabilised biowaste PAS 110: 2008 (Class 1) (Proposed) PTEs /elements (mg/kg dry weight) Cd 1.5 1.5/1.9 1.5 5 Cr 100 100/113 150 600 Cu 200 100/125 150 600 Hg 1.0 1.0/1.3 1 5 Ni 50 50/63 75 150 Pb 200 200/250 150 500 Zn 400 200/250 400 1500 Pathogens Salmonella absent Absent in 25 g fresh matter NA NA 1000 CFU/g fresh E. coli 1000/ 1500CFU/g dry matter NA NA mass Physical contaminants 0.5 (of which 0.25 is Total glass, plastic and plastic) 0.5/ 0.6 % mass/mass dry matter other non-stone NA NA % mass/mass of air of which none are “sharps” fragments > 2 mm dry sample Stones > 4 mm in No upper limit, declare as part of 8 % mass/mass of air grades other than typical or actual characteristics, NA NA dry sample “mulch” % m/m dry matter 2/3 viable weed seeds per Weed seeds 0 NA NA propagules per litre CFU – colony forming units
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3.5. Industrial waste materials
3.5.1. Introduction
Industrial waste is generated by factories and industrial plants. In England and Wales, approximately 50 million tonnes of industrial waste are produced every year and, of this, only 2.6% were used on land (FoE, 2003). According to the Waste Management Licensing (England and Wales)(2005) agricultural land can be treated with wastes from a range of industries when such “ treatments result in benefit to agriculture or ecological improvement ”.
Industrial wastes included in the regulations and considered in this section are: Pulp and paper industry sludge Waste wood, bark and other plant material Dredgings from any inland waters Blood and gut contents from abattoirs Textile waste Tannery and leather sludge Waste from food and drinks preparation Waste from chemical and pharmaceutical manufacture Waste lime and lime sludge Waste gypsum Decarbonation sludge Drinking water treatment sludge
Natural compounds such as oils and fats may be present in high levels in dairy, wool scouring, abattoir, meat processing, oil crushing and rendering wastes (Davis and Rudd, 1999). Detrimental effects on plant growth have been observed with wastes that have above 4% fat or oil content. Oils and fats are likely to coat soil particles, thus producing a waterproof barrier, and plants are not able to extract the water (ADAS, Imperial College, JBA Consulting, 2005). Microbial breakdown of the oil or fat can also result in temporary anaerobic conditions that may cause crop damage. Therefore, the pre-treatment of these wastes is recommended to reduce the fat or oil content to < 4% by separation and alternative disposal of this component of the waste (Davis and Rudd, 1999).
Organic contaminants in materials spread onto land are not routinely monitored and may raise concerns about the potential quality and impacts of these wastes. Nevertheless, quantities applied onto land are small and according to Aitken et al. (2002) they are not likely to represent a significant issue for may industrial wastes applied onto land as they are not in direct contact with organic chemicals, such as in a manufacturing process or from urban or industrial discharges (Table 3.30). Some exceptions include residuals from processes where colouring, bleaching or preservative agents and pesticides might be used (ADAS, Imperial College, JBA Consulting, 2005). The Food and Environment Research Agency 69
Table 3.30 Assessment of likely concentrations of organic contaminants in a range of wastes (Aitken et al., 2002) Waste Risk Waste soil or compost L Waste wood, bark and other plant matter L Waste food, drin k or materials used in their preparation L Blood and gut contents from abattoirs L Waste lime L Lime sludge from cement manufacture or gas processing L Waste gypsum L Paper waste sludge, waste paper and de -inked paper pulp M Dredgings from any inland waters L Textile waste M Septic tank sludge M Sludge from biological treatment plants M Waste hair and effluent treatment sludge from tanneries M L = low unlikely to be a problem M = Moderate a possible problem unless strict precautions are followed H= high likely to be a serious problem unless strict precautions are carried out
3.5.2. Legislation
There is no specific legislation on the landspreading of industrial wastes to land. In the European Commission working document on the Biological Treatment of Biowaste (EC, 2001) all the biowastes suitable for biological treatment and/or spreading on the soil are listed in Appendix C. In the Waste Management Licensing for England and Wales (2005) legislation a list of wastes that can be spread on land is also available. Legislation for the use of industrial wastes on land are reported in Table 3.31.
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Table 3.31 Legislation/ voluntary initiatives on the use of industrial wastes on land Title Measures P/L/V PTEs OCs Pathogens Industrial wastes used in agriculture are exempt if Waste Management Licensing it is shown that they provide “agricultural benefit L D I I Regulations (2005) and ecological improvement” Environmental Permitting Exemption from an environmental permit for a (England and Wales) L I I I range of industrial wastes Regulations 2007 EU Animal By-Products Blood needs to be treated before land application L I Regulations (2002) UK Animal By-Products Implements the ABPR in the UK L I Regulations (2005) Code of practice for “Properly Qualified Advice” should be sought for Landspreading Paper Mill assessment of the suitability of a landspreading V D I I Sludge (1998) site and paper waste properties for landspreading Defra guidance: Application f dredging to agricultural land The N content of dredging must be taken into L I I I (2002). Particularly in relation account when spreading to agricultural land to the NVZ Action Programme Biological Treatment of Not applied D I Biowaste, 2001 – 2nd draft PTEs – potentially toxic elements; OCs – organic compounds P-Policy, L- Legislation, V-Voluntary measure D - Direct, I - Indirect . Legislation has a direct effect if its purpose is to control/limit inputs of a contaminant to soil. Indirect legislation may have implications for contaminant inputs to soil without this being its primary purpose.
3.5.3. Pulp and paper industry Sludge
3.5.3.1. Introduction
In this section, the pulp and paper sludge category includes: paper waste sludge, waste paper and de-inked paper pulp.
Paper mills have been spreading paper wastes on agricultural land for around 30 years. The quantity of paper waste materials spread on agricultural land in England and Wales in 2003 was estimated to be 280 000 tonnes on a dry solids basis and were applied to 10 500 hectares of agricultural land (Gibbs et al., 2005).
There are a number of benefits of the application of paper wastes to agricultural land including liming value, nutrient supply and soil conditioning properties and these were confirmed by experimental data (Gibbs et al., 2005). Application of organic matter applied as paper waste improves soil characteristics such as porosity, moisture retention, structural stability and bulk density, and soil biological activity and microbial and faunal populations (Gibbs et al., 2005). Reported negative impacts included heavy metal load, organic contamination and odour generation. Nevertheless, levels of these contaminants were similar to those of other commonly applied organic materials (Gibbs et al., 2005). Another reported disadvantage was the high carbon/nitrogen (C/N) ratio that will deprive crops of nitrogen or immobilize nitrogen in the soil matrix (Davis and Rudd, 1999). However, the addition of extra inorganic fertilizer nitrogen has been reported to overcome this problem (Gibbs et The Food and Environment Research Agency 71
al., 2005). Generally, no extra nitrogen has been applied following spreading of biologically treated paper wastes, while extra nitrogen has been applied when paper wastes have been chemically/physically treated (Gibbs et al., 2005).
3.5.3.2. Treatment
Based on nutrient content and heavy metal concentrations, paper wastes produced in England and Wales can be split into two categories: (i) paper wastes with a biological element in the treatment processes and (ii) paper wastes with none or small biological element in the treatment process. Paper waste from paper mills result from two-treatment routes - primary and secondary treatment processes. While the primary treatment is a physical treatment, the secondary treatment may be chemical/physical or biological (Gibbs et al., 2005). The sludge produced may be composted, or anaerobically digested. It may also be used for co-digestion with other wastes.
3.5.3.3. Contaminants
PTEs
Concentrations
Regarding dry solids, total nutrient content and heavy metal loadings, there are clear differences between secondary biologically treated paper waste and primary or secondary chemically/physically treated paper wastes. Biologically treated paper wastes have lower dry solids content, higher nutrient and heavy metal content than chemically/physically treated wastes. Data on the concentration of PTEs found for paper waste following the different treatments are presented in Table 3.32. In general, heavy metal concentrations in paper wastes are below those found in sewage sludge (Gendebien et al., 1999), and similar to those present in animal manures (ADAS, 2002) or other organic waste materials (Gendebien et al., 2001).
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Table 3.32 Concentrations of metals in paper sludge, de-inked paper pulp and waste paper (mg/kg dry solids; mean (min;max)) Gibbs et al., 2005 Davis and Rudd, 1999 WRc, 2009 2 Secondary 3 Secondary 4 Paper waste sludge, Metals 1 Primary treated Paper waste sludge, waste biologically treated chemically/physically waste paper and de- n paper sludge paper and de-inked paper pulp paper waste treated paper sludge inked paper pulp Cd <0.2 (<0.2; 0.9) 0.7 (0.4; 1.1) <0.2 (<0.2) 0.02 (<0.25; 0.5) 0.29 (0.03; 5.07) 289 Cr 4.9 (1.2; 23.9) 18.2 (8.0; 41.4) 6.8 (0.2; 15.6) 2.4 (<1.0; 16.1) 11.97 (1.32; 82.6) 289 Cu 38.7 (10.8; 82.4) 110.2 (92.7; 123.6) 57.5 (5.8; 294.0) 32.8 (2.0; 349.0) 75.3 (2.5; 487.0) 293 Hg <0.2 (<0.2) <0.2 (<0.2) <0.2 (<0.2) <0.01 (<0.01; 0.03) 0.09 (0.01; 2.5) 283 Ni 2.8 (<0.2; 16.9) 10.5 (2.5; 33.4) 3.3 (<0.2; 7.5) 1.3 (<1.0; 8.7) 11.5 (0.02; 292.3) 282 Pb 8.4 (2.1; 46.9) 29.1 (23.3; 36.4) 7.8 (<0.2; 38.9) 1.7 (<1.0; 14.8) 7.67 (0.005; 85.9) 289 Zn 51.4 (12.2; 186.2) 138.5 (95.6; 226.5) 115.3 (6.5; 437.2) 29.4 (1.3; 157.0) 60.6 (0.16; 310.0) 294 NA- not available; n- number of samples; 1-assumes dry solids content of 42.6%; 2- assumes dry solids content of 27.5%; 3- assumes dry solids content of 39.8%; 4- These data is an average of the metal content in paper waste sludge, waste paper and de-inked pulp paper.
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Organic compounds
Organic contaminants in this waste include surfactants used in flotation process (Tandy et al., 2008), and fatty and resin acids and PAH’s (Beauchamp et al., 2002; Rashid et al., 2006). Beauchamp et al. (2002) claimed that the sludge could contain 150 different organic compounds.
Concentrations
Average concentrations of organic contaminants in paper waste sludge have been reported by Gendebien et al. (2001) for France, Benelux, England and Finland and these data are summarized in Table 3.33.
Table 3.33 Organic contaminants concentrations in the pulp and paper industry sludge (in mg/kg dry weight; Gendebien et al., 2001). Contaminant Min Max Average Fluoranthene 0.01 <0.1 <0.05 Benzo(b)fluoranthene <0.005 0.04 <0.02 Benzo(a)pyrene <0. 005 0.03 <0.02 Sum of 7 PCBs 0.002 <1 <0.5
Data has also been found for Canada. Webber (1996) reported that total concentrations of dioxin and furans (PCDD/Fs) were low and that 2,3,7,8- tetrachlorodibenzo-p-dioxin toxicity equivalents (TEQ) ranged from 1.3 to 13.6 ng/kg dry solids. In combined primary and secondary sludges from a paper mill in Canada, PCDD/Fs were below 12 ng TEQ/kg dry solids when treated with chlorine and below 3.5 ng TEQ/kg dry solids when no chlorine was used. A review on the organic contaminants of paper mill sludges in Canada reported low concentrations for phenolics, polychlorinated biphenyls, xylene, phthalate esters, chlorodioxin/furans and volatile compounds (Bellamy et al., 1995). In another study, Trepanier et al. (1998) reported levels below the limits for soils in de-inked paper sludges for aromatic hydrocarbons, polychlorinated byphenyls and polynuclear aromatic hydrocarbons. Overall, concentrations of these organic contaminants in paper sludges were low, within the acceptable Canadian limits, and would not pose any constrain on the application of paper wastes in agriculture.
Levels of AOX in paper sludges were reported to reach or exceed 500 mg/kg dry solids (Welker and Schmitt, 1997). However, these compounds are insoluble in water and environmental impacts due to landspreading are likely to be insignificant (Gibbs et al., 2005).
Pathogens
With regard to pathogens content in paper wastes, Davis and Rudd (1999) concluded that they can be regarded as pathogen and parasite free and that no risks to human health, animal, or plants would arise. However, data on the survey performed by
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Gibbs et al. (2005) revealed the presence of E. coli levels that ranged from non detectable to 20,000 colony-forming units per gram of dry solids in paper wastes that had undergone secondary biological treatment (e.g. composting). During biological treatment, re-growth of pathogens might be possible if the optimal temperature has not been reached (above 55°C; Elving, 2009). It is however unlikely pathogens would be present in primary or secondary chemically/physically treated materials (Gibbs et al., 2005).
3.5.4. Waste wood, bark or other plant material
3.5.4.1. Introduction
Waste wood, bark or other plant material might originate from timber yards (sawdust and shavings), municipal parks and gardens, from any processing of vegetable matter (e.g. sugar beet, vegetables, green waste), chipboard, fibreboard and medium density fibreboard processing, pallets and reclaimed timber from building sites and packing crates (Davis and Rudd, 1999).
In the UK, 10 million tonnes of waste wood are being produced each year, most of which goes to landfill.
The high organic carbon content of waste wood, bark or other plant matter has long- term benefits to agricultural land. Immediate benefits to discourage weed growth and conserve soil moisture are obtained by applying chipped wood or bark as a mulch (Davis and Rudd, 1999). Potential negative impacts are dependent on the nature of the production process. Following application to land, wood products with a high C/N ratio can temporarily remove plant-available nitrogen from the soil. Additional inorganic nitrogen should be applied to the soil to compensate for this and avoid crop yield and quality loss.
3.5.4.2. Treatment
The physical quality of these materials might be improved by screening and shredding. Many of these materials are suitable for composting (Gendebien et al., 2001). Much of the plant material waste from parks and gardens goes to mechanical biological treatment facilities or straight to compost.
3.5.4.3. Contaminants
PTEs
Heavy metal content of wood wastes and other plant materials are low. CCA, copper organics, and metals in paints may be present in wood waste. PTEs are unlikely in plant waste and untreated wood unless they have been grown on contaminated ground. Heavy metal concentrations reported for these wastes are from the UK and are presented in Table 3.34.
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Table 3.34 Concentration of PTEs in waste wood, bark and other plant material (mg/kg dw; Davis and Rudd, 1999) Metals Mean (min; max) Cd <0.25 Cr 3.3 (<1; 9.9) Cu 4.8 (3.1; 6.4) Hg <0.01 Ni 0.3 (<1; <1) Pb 2.4 (<1; 3.7) Zn 18.5 (14.6; 22.3)
Organic compounds
Pesticides, creosote, light organic solvent preservatives (LOSP), micro-emulsion, paint and stain, and varnish may be present in the waste.
Wood preservatives and pesticides such as pentachlorophenol, lindane or copper chrome arsenate might be present in these wastes and therefore, the presence of contaminants should be investigated prior to application. Concentrations of organic compounds detected in waste wood, bark and other plant material are reported in Table 3.35.
Table 3.35 Concentrations of organic compounds detected in waste wood, bark and other plant material (Gendebien et al., 2001) Organic compound Mean Sum of 6 PAHs 0.6 Sum of PCBs 0.008 PCDD/F green waste 4.96 ± 3.56 ng TEQ/kg ± SD PCDD/F in bark 1 ± 0.57 ng TEQ/kg ± SD
Pathogens
Wood waste from joinery and similar processes are unlikely to contain any harmful organisms (Davis and Rudd, 1999).
With green plant material and rotted roots there is a possibility of plant pathogens, particularly fungi being present (Davis and Rudd, 1999). Therefore, the origin of waste plant matter has to be considered in case diseased material is present that could act a source of infection for crops. Examples are haulms of potatoes infected with the potato blight fungus Phytophthora infestans and rotten wood may harbour the honey fungus, Armilleria , which can destroy trees and shrubs (Gendebien et al., 2001). Noble and Roberts (2004) reviewed plant pathogens and nematodes, and common name of plant diseases caused by these (Table 3.36). In Appendix D, plant
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toxins that may occur in green compost are listed and these can also be present in plant material (WRAP, 2009).
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Table 3.36. Plant pathogens and nematodes, hosts and common name of diseases caused, or of nematodes (Noble and Roberts, 2004)
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Table 3.36 (cont.) Plant pathogens and nematodes, hosts and common name of diseases caused, or of nematodes (Noble and Roberts, 2004)
3.5.5. Dredgings from inland waters
3.5.5.1. Introduction
Dredging is an activity essential to navigation, maintaining the ecology and biodiversity of waterways and adjacent land, the management of flood risk and drainage activity. The consequences of not dredging, or carrying out limited dredging, can be significant (AINA, 2007).
Dredgings are usually deposited near the area where they have been taken and if suitable might be applied onto surrounding areas as it is very expensive to transport the material, since it is heavier because of water content. Dredgings that are unsuitable for landspreading due to contamination are disposed into landfills (Gendebien et al., 2001).
Potential benefits for the application of dredgings to land are the supply of organic matter and nutrients in the form of phosphate and organically bound nitrogen (Davis and Rudd, 1999). If the dredgings are sandy and thus low on organic carbon content they can be used for levelling purposes (Davis and Rudd, 1999). Disadvantages for the landspreading of dredgings are mainly due to levels of contaminants and the presence of undegradable plastic litter and metal scrap items that they might contain, which could impede cultivation of the soil and be hazardous to farm animals (Davis and Rudd, 1999). The mud of dredgings contains a high proportion of silts and clays that are highly adsorptive of bacteria and viruses as well as metals and organic contaminants (Davis and Rudd, 1999).
3.5.5.2. Treatment
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Following recovery, dredgings are likely to be anaerobic and odorous and will probably need to be aerated before landspreading (Gendebien et al., 2001). If there is the presence of plastic and scrap metals they also need screening.
3.5.5.3. Contaminants
PTEs
The data available on heavy metal and other elements concentrations are from samples of dredgings from a 100 km length canal (Davis and Rudd, 1999) and other places in the UK (WRc, 2009). Available data are summarized in Table 3.37. Heavy metal content in dredgings is high.
Table 3.37 PTEs /elements and other inorganic chemicals reported in dredgings (in mg/kg dw) Davis and Rudd, 1999 ADAS , 2009 WRc, 2009 Metals/elements Mean (min; max) *Mean Mean (min; max) n Ag 0.1 (0; 23.1) NA NA NA As 47.4 (9; 873) 19.0 NA NA B 45.0 (9.9; 172) NA NA NA Ba 243.8 (38.6; 731) NA NA NA Be 1.8 (0.8; 9.7) NA NA NA Cd 2.2 (0; 21) 3.0 0.76 (0.05; 4.2) 18 Co 36.4 (15; 94) NA NA NA Cr 159.7 (25; 4011) 82.0 23.8 (3.03; 86.8) 18 Cu 136.8 (26; 1357) 152.0 56.6 (2.12; 242.8) 19 Hg 83.0 (0.1; 1570.7) 1.6 0.38 (0.04; 1.9) 18 Mg NA NA 3501.5 (9.88; 17204.3) 9 Mo 1.6 (0; 7.1) NA NA NA Ni 79.3 (34; 204) 73.0 105.3 (7.8; 973.1) 18 Pb 408.9 (22; 8275) 166.0 168.4 (0.01; 1750) 19 Sb 10.0 (0; 146) NA NA NA Se 3.7 (0.1; 23.1) NA NA NA Sn 33.2 (9.7; 278) NA NA NA Tl 0.1 (0; 5.2) NA NA NA Va 68.7 (37.8; 104) NA NA NA Zn 958.1 (154; 6671) 545.0 213.4 (25.9; 1063.0) 19 Inorganic compounds Cyanides 0.6 (0; 2.6) NA NA NA Sulphides 1805.1 (0; 6330) NA NA NA NA - not available *Mean analysis of 1000 British Waterways canal dredging samples based on 48% dry matter content.
Organic compounds
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A summary of the range concentrations of organic contaminants by class reported in sediments is presented in Table 3.38. All data, including individual compounds can be found in Appendix E.
Table 3.38 Summary of range concentrations (minimum value, highest maximum and highest mean reported within the class) for organic contaminants detected in sediments in µg/kg dry weight (unless otherwise stated)(Allchin et al., 1999; Eljarrat and Barcelo, 2003; Long et al., 1998; Daniels et al., 2000; Buser et al ., 1998; Braga et al., 2005; Ternes et al., 2002; López de Alda et al., 2002; Ferrer et al., 2004; Davis and Rudd, 1999; Metre and Mahler, 2005; Micić and Hofmann, 2009; Eljarrat and Barcelo, 2004) Contaminant Minimum Maximum Mean (highest) Brominated flame retardants <0.17 750 86.39 Pesticides nd 11 658 3002 Pharmaceuticals nd 48.6 NA Phenols 2.1 292 23.4 Pht halates (DEHP) 229 19 421 7871 ∑ PAHs 0 203 8900 (median) ∑ PCBs NA NA 108 (median) ∑PCDD/Fs 0.02 59 000 NA Surfactants <0.5 2.83 mg/kg 30
Contamination of freshwaters with micro-organic compounds from agricultural or industrial sources is common worldwide (Long et al., 1998). Long et al (1998) investigated the pollution by organic contaminants in riverine systems in Northeast England. Bed sediments from six freshwater tributaries of the Humber River were collected for one year in 1995-96. In another study, Daniels et al (2000) collected river bed sediments cores below a depth of 5 cm from a urban catchment and from a rural river in South England. Results from these studies can be seen in Appendix E.
Metre and Mahler (2005) presented the trends of organic contaminants detected in sediment cores from 38 USA lakes over a period of 30 years. The two main conclusions were that organochlorine pesticides and PCBs concentrations were decreasing over time, whereas PAHs concentrations are increasing (Metre and Mahler, 2005).
Pharmaceutical concentrations in sediments, which are mainly hormones and steroids, have been also recently published in a review paper (Monteiro and Boxall, 2010).
Pathogens
Risks from pathogens in sediments have been reported to be low and unlikely to be a problem when this organic material is spread onto land (SEPA, 1998). However, a recent publication reported that bacteria counts within sediment compartments were consistently higher than for the water alone, and that the bed sediment were The Food and Environment Research Agency 81
found to represent a possible reservoir of pathogens (Droppo et al., 2009). Levels of pathogens in bed sediment in colony-forming units were 1,3 x 10 5 for E. coli and 1.2 x 10 5 for Salmonella (Droppo et al., 2009). The lack of understanding on pathogen/sediment associations may lead to an inaccurate estimate of public health risk (Droppo et al., 2009). 3.5.6. Abattoir wastes
3.5.6.1. Introduction
In this section, wastes from abattoirs include blood, gut contents, wash waters, and sludge from dissolved air flotation (DAF) treatment where this process has been used for the separation solids from any liquid waste materials of the abattoir (Davis and Rudd, 1999).
It has been reported that 21% of an animal is waste when processed (Gendebien et al., 2001). Some of the abattoir wastes, such as bones and hoof parts are recycled in other industries (e.g. fertiliser and gelatine). In the EU, between 5 to 10 % of abattoir waste is applied to land following composting or without any further treatment. This waste mainly consists of gut contents, wash waters and blood (Gendebien et al., 2001). For small-scale abattoirs, landspreading of the waste is probably the best environmental option but likely to be much less appropriate for large-scale operations (Mittal, 2007).
Whereas waste blood and stomach contents have a high fertilizer value due to their high nitrogen, phosphorus and potassium content, which makes them a good source of plants nutrients, wash waters contain lower levels of nutrients (Mittal, 2007). Abattoir wastes may also have a high conductivity and fat content (Davis and Rudd, 1999). Blood and gut content from abattoirs are included in the exempt industrial wastes for land application. Since most of the exempt wastes are not pre-treated or stored at the point of source, it can cause public nuisance due to odours, environmental concerns and if spread on the soil surface it is unsightly and may have the potential for disease transmission (Mittal, 2007). It is recommended that these wastes should be immediately incorporated into arable land, or applied to grassland by sub-surface injection following a 3 week period to allow the injection slots to close before the use of the grass for grazing or conservation (Davis and Rudd, 1999).
Blood
Waste blood is produced in large quantities from abattoirs and used to be applied onto land without further treatment as a source of nutrients. Nitrogen content in waste blood is extremely high, typically exceeding 15 kg/m 3 total nitrogen and 2 kg/m 3 of ammonium nitrogen. The high nitrogen content combined with potassium and phosphorus contents of 1 to 2 kg/m 3, waste blood provides a good source of plant nutrients, which are in a more available form when compared to other organic wastes (Davis and Rudd, 1999). Potential disadvantages are if applied in excess to plant requirements, these high levels of elements might cause water pollution and pose a danger to plant health (Gendebien et al., 2001). Abattoir wastes also have a The Food and Environment Research Agency 82
high biological oxygen demand (BOD) that makes it readily degradable by soil microorganisms and thus over application can result in anaerobic soil conditions (Davis and Rudd, 1999). In the EU, however, from the 1 st May 2003, the EU Animal By-products Regulations require that certain by-products need to be treated before disposal (Defra, 2003). Therefore, it is no longer permitted the disposal of untreated blood to sewers or landfill or to recover untreated blood via application on land.
Gut contents
Gut contents mainly consist of partially digested feed or vegetable matter. Nitrogen (5 kg/m 3), phosphorus (1 kg/m 3) and potassium (1 kg/m 3) levels are high and in a balanced mixture (5:1:1). Gut contents also contain ammonium nitrogen as an added benefit (Davis and Rudd, 1999). The main disadvantages of gut contents are the odours depending on the storage period and it might also contain pathogens.
Wash waters
Large volumes of wash waters are produced within abattoirs. These wash waters might contain urine and dung from animal holding areas and washings from distribution vehicles. Levels of nitrogen (1 kg/m 3), phosphorus (0.5 kg/m 3) and potassium (0.5 kg/m 3) are lower when comparing to other abattoir wastes. A moderate content of ammonium nitrogen (0.25 kg/m 3) is also available. Agricultural benefit from wash waters from abattoirs might not be achieved unless it is used for irrigation (not for growing crops or grassland). This water waste might also contain pathogens (Davis and Rudd, 1999).
Other abattoir wastes
Other abattoir wastes include waste from where animals are temporarily kept (also known as lairage), wastes from biological treatment plants and fat (Davis and Rudd, 1999; WRc, 2009). Due to the amount of blood in wastes for treatment and disposal, the nitrogen content can be very high, in excess of 8 kg/m 3 and ammonium nitrogen typically exceeding 1 kg/m 3. Potassium, phosphorus and magnesium can be in excess of 1 to 2 kg/m 3. Different types of abattoirs produce different types and amounts of fat, but chicken processing plants are sources of high fat materials. Adverse effects on plant growth following application of animal fat have been observed at relatively low fat percentages when compared to wastes containing other fats and oils (Davis and Rudd, 1999). These wastes should also be incorporated into the soil.
3.5.6.2. Contaminants
PTEs
In the UK, the presence of metals has been reported for abattoir wastes (Davis and Rudd, 1999) and a recent study from WRc (2009) collated data from different kinds of abattoir wastes that can be spread onto land. Metal levels in blood (not treated The Food and Environment Research Agency 83
for data before 2003 and treated for data after 2003), gut contents and wash water from these studies are summarised in Table 3.39.
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Table 3.39 Metal concentrations in abattoir wastes in the UK (mean (min; max) in mg/kg) Davis and Rudd, 1999 WRc, 2009 Metals Blood n Gut contents n Wash waters n Blood n Gut contents n Wash waters n <0.25 90.36 0.01 0.02 82 <0.25 6 <0.25 14 10 4 7 Cd (<0.25; 0.68) (0.002; 0.5) (0.006; 0.018) (0.005; 0.05) 0.3 0.2 1.1 3.5 0.26 0.32 80 5 14 10 3 7 Cr (<1.0; 3.2) (<1.0; <1.0) (<1.0; 10.5) (0.01; 7.7) (0.132; 0.34) (0.01; 1.53) 3.2 2.4 2.1 35.9 1.06 0.59 54 5 12 11 4 8 Cu (0.3; 34.1) (0.8; 7.5) (1.0; 5.5) (0.23; 53.2) (0.80; 1.39) (0.005; 3.65) <0.01 0.03 <0.01 0.04 0.02 3.41 Hg 79 5 14 8 3 7 (<0.01; 10.24) (<0.01; 0.14) (<0.01; 0.04) (0.0002; 0.05) (0.0001; 0.04) (0.42; 9.62) 0.4 0.8 <1.0 4.32 0.29 0.30 83 6 14 10 3 7 Ni (<1.0; 5.7) (<1.0; 4.6) (<1.0; 4.35) (2.0; 4.9) (0.25; 0.33) (0.03; 1.11) 0.3 0.4 <1.0 91.3 0.16 0.18 Pb 83 6 14 9 4 7 (<0.1; 10.0) (<1.0; 2.1) (<1.0; 1.5) (0.5; 116.3) (0.11; 0.23) (0.06; 0.5) 12.8 9.0 18.4 11.3 8.4 123.1 73 6 13 11 5 8 Zn (1.0; 87.2) (2.4; 34.1) (1.8; 115.0) (0.03; 40) (4.98; 13.4) (35.3; 293.7) n – number of samples
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Organic compounds
In addition to veterinary medicines described in the livestock manure section, wash water chemicals may contaminate the waste stream. Careful selection of washing detergents using Environmental Risk Assessment (ERA) will minimise any risk from cleaning chemicals.
Very few data was found in the literature reporting the investigation of organic contaminants in abattoir wastes and these data has been summarized in Table 3.40 (Gendebien et al., 2001). SEPA (1998) reported a low risk for adverse effects from organic contaminants, and that these compounds in abattoir wastes are unlikely to pose any problems.
Table 3.40 Organic contaminants in abattoir wastes (in mg/kg dry weight; Gendebien et al., 2001) Stomach contents Sludge Organic contaminants Min Max Min Max Fluoranthene <0.1 <0.5 <0.1 <0.5 Benzo(b)fluoranthene <0.1 0.4 <0.1 0.4 Benzo(a)pyrene <0.1 0.6 <0.1 0.6 Su m of 7 PCBs <0.0007 0.2 <0.0007 0.2
Pathogens
Abattoirs veterinary ante-mortem inspections ensure that the animal used for human consumption is not suffering from any noticeable disease. However, slaughtered animals may carry pathogenic bacteria without any symptoms and thus abattoir wastes should be used with caution (Davis and Rudd, 1999).
In a study by Pepperel et al. (2003), 28 commercial abattoirs were surveyed for quantitative levels of pathogens in wastes to be applied onto land. In all wastes studied (lairage, lairage/stomach content, stomach content, blood and effluent) the most common bacterial pathogen found was Campylobacter , with an average incidence of 5.7%. This pathogen was detected in effluent and blood from poultry abattoirs (12.5%, each) and in lairage and blood from red meat abattoirs (8.3%, each). Another pathogen, Listeria monocytogenes was found in only 1.1% of all waste samples but not in any sample from poultry abattoirs. Salmonella and E.coli were not isolated from any abattoir waste sample. The overall incidence of the protozoan pathogens Giardia and Cryptosporidium in red meat waste abattoirs was around 52.5% and 40%, respectively. The most contaminated waste type with protozoan pathogens was lairage waste followed by effluent (Pepperel et al., 2003). In another study, Mittal (2004) reports that abattoir wastewater contains several million colony forming units (cfu) per 100 ml of total coliform, faecal coliform and Streptococcus groups of bacteria and that the presence of these non-pathogenic microbes indicates the possible presence of pathogens of enteric origin such as the ones mentioned in the study by Pepperel et al. (2003).
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3.5.7. Textile industry waste
3.5.7.1. Introduction
Textile waste comprises either textile processing industry sludge or wool industry waste. Sludge from process industry may be liquid or in viscid form, depending on the level of dewatering. Wool waste is very fatty, viscid sludge that cannot be spread as it is. However, it can be spread in the form of dry waste (wool dust).
Textile industries use large volumes of water because textile products undergo different and successive treatments such as pre-washing, bleaching, pre-treatment, dying, soaping, washing, initial dressing, second dressing, rinsing, etc. Quality of the effluents produced by the textile processing industry depends on the type of fibres, the dyeing and printing processes and the products used. The effluents have a high chemical oxygen demand (COD), which is difficult to breakdown by chemical or biological processes.
Textile waste contains little organic matter, average nitrogen content and low levels of phosphorus and potassium that are not very beneficial for plant growth. Textile waste also has low C/N ratio that would make the little organic matter break down quickly following application to soils (Gendebien et al., 2001). Therefore, textile waste has low agronomic value that could be improved with liming or composting with an additional carbonaceous structuring medium. On the other hand, waste from the wool industry has much more agronomic value due to higher potassium and magnesium content.
3.5.7.2. Treatment
Some textile industries have on-site effluent treatment plants that usually use traditional biological procedures that might be preceded by physical-chemical pre- treatment. Characteristics of sludge from the treatment of textile industry effluent are dependent of the type of treatment applied to the liquid waste, which might be physical-chemical (coagulation-flocculation) or/and biological (Gendebien et al., 2001).
Concentrates from washing the wool contain fatty matter that cannot be applied to land as they stand. Therefore, these wastes need to be mixed with bark to make them like pellets so they not adhere to the handling equipment. This type of mixture can create a potassium based organic medium. This breaks down slowly in the soil due to soil nitrogen and is rich in potassium, sodium and magnesium (Gendebien et al., 2001).
The dust from the wool is a dry waste with a C/N ratio of around 6, and rich in potassium and nitrogen. However, it can cause problems since it can contain plant seeds that following application colonise the area being spread (Gendebien et al., 2001).
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3.5.7.3. Contaminants
PTEs
Textile processing sludge can contain higher levels of metals than other industrial sludges that are spread onto land. Dyes used in the textile industry may contain various metals that contribute for the colouring effect. Therefore, the washing process takes dyes residues into effluents treatment plants that can concentrate into the sludge. Levels of metals on the order of several 100 mg/kg can result (Davis and Rudd, 1999). Chromium levels, for example, are generally higher than those found in domestic sewage sludge due to the use of metalliferous dyestuffs. However, levels are still below the limits established for landspreading (Gendebien et al., 2001). Concentrations of metals from wastes derived from the textile industry are reported in Table 3.41. Wool washing/wool combing industry by-products contain few metals.
Table 3.41 Metal concentrations in textile waste in mg/kg dw. Textile waste sludge Wool scourers Metal /element *Gendebien et al., 2001 WRc 2009 (n=6) *Gendebien et al., 2001 WRc 2009 (n=5) Mean (min; max) Cd 0.5 (0.15; 1.2) 0.26 (0.08; 0.3) 0.5 (<0.25; 0.7) 0.17 (0.12; 0.18) Cr 40 (<1; 430) 9.5 (0.005; 11.4) 14 (1.5; 20) 11.5 (10.9; 14.0) Cu 131 (0.5; 892) 31.5 (0.5; 37.7) 13 (1.7; 26) 29.3 (22.7; 31.0) Hg (0.4 (<0.01; 3.1) 0.25 (0.005; 0.30) 0.06 (<0.01; 0.1) 0.22 (0.006; 0.27) Ni 8 (<1; 31) 7.9 (0.005; 17.4) 7 (0.5; 9) 2.6 (0.9; 9.5) Pb 7 (<1; 22) 12.0 (6.1; 13.2) 7 (1.3; 11) 5.3 (4.7; 5.5) Se 4.6 (1.8; 5.4) NA 8 NA Zn 188 (1.4; 1249) 266.2 (49.3; 310) 62 (12; 95) 301.8 (124.6; 346.1) *number of samples is not available NA – not available
Organic contaminants
All waste types from textile manufacturing contain a variety of organic contaminants. Textile industry includes finishing processes where the textiles are dyed. Methods used for bleaching the fabric can lead to concentrations of organo-halogenated compounds in the sludge. Oxidisation techniques such as ozonation and UV radiation are now being tested to destroy some of the AOX present in the sludge (Gendebien et al., 2001).
Wool processing by-products are likely to contain organic compounds from treating fleeces with pesticides that end up in the sludge when the wool is washed. Pesticides are used to treat sheep, such as sheep dip or to treat the wool. Organophosphorus and organochlorine compounds are often found in association with the grease fraction of the sludge. Imported wool can be found to contain compounds such as gamma-HCH (lindane) and DDT. Surfactants are widely used in the textile finishing industry. All types of surfactants (anionic, non-ionic, cationic and amphoteric) are used but anionic and non-ionic substances dominate. Surfactants in the textile industry serve mainly as detergents, The Food and Environment Research Agency 88
wetting agents, de-aeration agents, leveling, dispersing and softening agents, emulsifying and spotting agents, anti-electrostatics, foaming and defoaming agents, after-treatment agents for improving dye fastness improvement and accelerating dye fixing (OECD, 2004).
Collection water also contains small amounts of degradation products that result from the breaking down of bleaching agents and dyestuffs.
Most industries are negligible sources of PCDD/Fs to municipal wastewater treatment (ADAS, Imperial College, JBA Consulting, 2005). Nevertheless, industrial sources of PCDD/Fs to wastewater can be important. In a study by Klöpffer et al. (1990 cited in McLachlan et al., 1996) identified the textile industry as the most important industrial sources of PCDD/Fs to wastewater treatment plants. They also suggested that pentachlorophenol that contains trace amounts of PCDD/Fs was a major source of contamination within the textile industry.
In the textile industry, biocides are also used to control bacteria, fungi, mold, mildew, and algae. This control reduces or eliminates the problems of deterioration, staining and odours (White and Kuehl, 2002). About 5 % of textiles are finished with biocides for the consumer end-use (OECD, 2004). In the carpet industry biocides play an important role to impart wool fibre lifetime. Mothproofing agents formulated from synthetic pyrethroids (permethrin and cyfluthrin) are used against a range of textile pests. Permethrin -based formulations account for approximately 90 % of the market (OECD, 2004). Additionally, biocides may be present on textiles for the following reasons: Biocides are used to improve storage stability of textiles (preservation agents); Biocides in raw cotton fibres such as insecticides (organochlorines, organophosphates, pyrethroids, and carbamates), herbicides, harvest aid chemicals; and Residues of biocidal chemicals are used to prevent or treat sheep infestations by external pests (ectoparasites such as ticks, mites and blowfly) and might therefore be present in greasy wool. These are removed in wool scouring into the wastewater. Biocide contents of the processed wools is variable and dependent of the countries of origin of the wools: Organochlorines: 0.2 to 5 g t -1 greasy wool Organophosphates: 1 to 19 g t -1 greasy wool Pyrethroids: 0.05 to 6.3 g t -1 greasy wool.
Biocides typically used in the textile industry include (OECD, 2004): 2,2’-Dihydroxy-5,5’-dichlorodiphenylmethane 2-Phenylphenol Sodium-2-phenyl-phenolate. Quaternary ammonium salts Copper-8-quinolinolate Dichlorophen Zinc naphthenate The Food and Environment Research Agency 89
Thiobendazone Organotin compounds 2,4-Dichlorobenzyl alcohol 2-Bromo-2-nitropropane-1,3-diol.
Concentrations for organic compounds in textile waste are presented in Table 3.42.
Table 3.42 Organic compounds levels in textile waste in mg/kg dw (Gendebien et al 2001) Textile waste sludge Wool scourers Organic compounds Mean min; max Fluoranthene 0.06 <0.01; 0.04 Benzo(b)fluoranthene 0.05 <0.01; <0.01 Benzo(a)pyrene 0.02 <0.01; 0.01 Sum of 7 PCBs 0.01 <0.05; <0.05
Pathogens
Pathogens may be present in waste from fibre production but not from wastes further down the manufacturing line. In theory, there is still a risk that wool wastes might contain spores of the anthrax bacillus, Bacillus anthracis . However, preventive industrial practices and the virtual elimination of human and animal anthrax from most developed countries imply that the risk of using such wastes is negligible (Davis and Rudd, 1999).
3.5.8. Tannery and leather waste
3.5.8.1. Introduction
Wastes within this category are similar to textile wastes. The raw material in tannery industry is mammalian skin, which is derived principally from animals that are butchered for the food industry. The tannery process consists of transforming the raw hide into leather that has a significant value. This process follows a sequence of organised chemical reactions and mechanical processes using machinery. Among these processes, tanning is the fundamental stage that confers to leather its stability and characteristics (Gendebien et al., 2001). The manufacture of leather generates both liquid and solid wastes. The latter consist of hairs that can be composted if they are pre-degraded in the preparation of hides. The tanning operation is carried in an aqueous environment and during this operation collagen, the principal protein of the skin, will fix the tanning agents to their reactive sites to stop putrefaction. In order to be transformed into a commercial product, the leather is dried with colouring agents and then fat liquored with the natural or synthetic fats in order to render the leather flexible (Gendebien et al., 2001). The products that are capable of being fixed to skin are many and varied but they can be classified into three groups: Mineral tannins (mostly chromium). Quick, simple and very cost effective, that means 70% of used tannins. But the chromium has a very high impact on the environment. The Food and Environment Research Agency 90
Vegetable type tannins (mimosa, chestnut, quebracho). 20% of used tannins. Liquid sludge from vegetable tannins has no impact on the environment. Other organic tannins (formaldehyde, synthetic tannins, fish oil).
Tanneries are a process within the textile industry but tannery wastes can contain particular contaminants. Tanneries wastes contain high levels of nitrogen that are highly available due to the low C/N ratio of liquid sludge. However, it can also contain high levels of chromium and salts. These wastes can be odorous due to their high sulphide content.
Only sludge from tanneries using vegetable tannins can be landspread. The spreading of tannery sludge coming from a process using mineral tannins is often blocked because of its heavy metal content.
3.5.8.2. Treatment
Most tannery sludges are dewatered to reduce the storage space required and transportation costs (Gendebien et al., 2001). Composting of dewatered sludge can further reduce storage, odour problems and improve the C/N ratio (Gendebien et al., 2001). Fertilisers can be produced from tannery sludges with the addition of lime to the wastewater making it alkaline, then adding ferrous or aluminium sulfate to coagulate it. The mixture is then dewatered, leaving a sludge containing about 20% dry matter. The sludge can be fermented and composted before the application to land (Gendebien et al., 2001).
3.5.8.3. Contaminants
PTEs
Tannery wastes can contain high levels of chromium, which is particularly toxic for the environment and the regulations set strict tolerance levels both in sludge and in the soil. Levels of other PTEs are low. Tanning agents are chosen for the particular properties they give leather, and chromium is the most popular. Concentrations of PTEs in tannery sludge are presented in Table 3.43.
Table 3.43 Concentrations for PTEs in tannery sludge (mg/kg dry weight) Dav is and Rudd, 1999 Gendebien et al., 2001 Metals Mean (min; max) Cd <0.25 (<0.25; 0.04) 0.17 (0.15; 0.7) Cr (169.0; 305.0) 128 (92; 162) Cu <1.0 (<1.0; 1.6) 10 (8; 13) Hg <0.001 0.03 (0.03; 0.04) Ni <1.0 (<1.0; 0.84) 1.5 (1.1; 2) Pb <1.0 (<1.0; 2.1) 4 (2; 5) Zn (2.8; 10.2) 27 (20; 31)
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Organic compounds
Biocides may be used in a variety of processes in the tannery industry, and halogenated biocides are still in use (IPPC, 2003). Surfactants are also used in tanneries in many different processes including liming, degreasing, tanning and dyeing. The most commonly used surfactant is NPE (IPPC, 2003). No data has been found on the concentrations of organic compounds in tannery leather waste.
Pathogens
Pathogens may be present on the hides and remnant flesh at the very initial stages of the tanning process. Chemical and other treatments given to hides in tanneries effectively disinfect the waste, with the exception of the spores of the anthrax bacillus. In the past, infections occurred in workers handling these materials and sporadic cases in animals have been reported. However, these problems have now disappeared, as anthrax in farm animals is extremely rare in the UK (Davis and Rudd, 1999). 3.5.9. Waste from food and drinks preparation
3.5.9.1. Introduction
Waste from food and drinks preparation includes animal food wastes, such as dairy, egg processing, and meat processing, wastes from the breweries, distilleries and soft drinks preparation, and sugar and preserves producers. In this section wastes from animal food production are separated from wastes from other food and drinks preparation.
A large volume of waste from food and drink processing industries is re-used in animal feed (e.g. vegetable residue, oil production residue) and in the production of organic fertilisers.
The food processing industry uses large volumes of water, which produces large volumes of wastewater that is generally loaded with organic matter. The effluent produced in food industry contains high amounts of potassium, and since it is in solution in the liquid phase it is thus rapidly available to plants. Food processing industry effluent is variable in composition depending on the type of industry and the period of the year for seasonal industries and this effluent is either spread directly to land or treated in an on-site or domestic/industrial wastewater treatment plant, which generates sludge. The sludge produced by the effluent treatment plants contains high levels of organic matter and nitrogen with a low C/N ratio and needs to be stabilised because it ferments very easily, since the organic matter it contains break down rapidly. Therefore, these wastes can be odorous during storage and spreading.
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Food and drink processing industries effluents are frequently loaded with chloride and sodium from the cleaning agents used. If it is spread in too large quantities or under the wrong conditions, salts can damage soil structure, reduce the availability of soil water for plant uptake and be toxic to plant growth (Gendebien et al., 2001). The limiting factor for fertilizer irrigation and/or for spreading effluent or sludge is generally the nitrogen level for the dairy industry and frequently the potassium level for other industries.
Animal food wastes
This section examines waste management for three animal food categories: dairy, egg processing and meat processing.
Dairy wastes
The waste stream characteristics are dependent on the product being processed. In general, wastes from the dairy industry contain high concentrations of organic materials (e.g. proteins, carbohydrates and lipids), high nitrogen concentrations, high-suspended oil and/or grease contents, which need special treatment to minimize environmental problems.
Dairies use large volumes of water, mainly for cleaning. Many dairies have their own effluent treatment plants and produce large amounts of sludge that also contains high levels of nitrogen, potassium, phosphorus and organic matter. The more common practice throughout the dairy industry is to salvage, pool, and isolate recovered whey and dairy products for use as animal feed (Chambers, 1999). Land application is usually the last option for disposal of salvaged whey and dairy products. Application rates per acre and fertilizer value such as nitrogen and phosphates need to be considered when this method is used (Chambers, 1999).
Egg processing
During the processing of eggs the major sources that generate waste are during shell washing, candling (technique that uses light to check the quality of the egg), sizing and the washing and cleaning operations. Incidental waste is also generated from broken eggs. Whereas in rural settings most waste streams are applied onto land as fertilizer, in non-rural settings many facilities discharge to a sewage treatment plant (Chambers, 1999).
Meat processing
At meat processing plants where products are prepared for human consumption (e.g. pies, canned meat, stock, etc). Edible fats are rendered into edible tallow and lard. Some rendering of inedible fats and blood processing might also be carried out. Common salt and a range of chemicals for curing, smoking, preserving and colouring are used. These include sulphur dioxide (a preservative), potassium nitrate (for pickling), sodium nitrate (meat colour fixative) and sodium nitrite (for curing, The Food and Environment Research Agency 93
colouring and preserving). Detergents, bleach and disinfectants are also used for maintaining plant hygiene (DoE, 1995).
Preserves producers
Preserves producing industries produce an effluent that contains high levels of organic matter, potassium, chloride and sodium resulting from washing, peeling, blanching vegetables, and washing the equipment and the production areas (Gendebien et al., 2001).
Breweries and distilleries
Effluents from the brewing and distilling industry are usually treated in a treatment plant and might also be anaerobically digested. Anaerobic digestion is to reduce the amount of sludge being produced and to generate energy to heat the reactor where the process occurs (Gendebien et al., 2001). Brewery industry wastes contain grain husks and yeast separated during malting and brewing processes that is mainly used as animal feed or reprocessed for use in food or nutrient materials (Gendebien et al., 2001). Distillery effluent contains high levels of potassium, sodium and sulphur and little suspended material.
Sugar producers
Sugar producing effluents contain high levels of suspended materials including soil particles and other organic residues. These effluents contain high levels of potassium, nitrogen, chloride and sodium. Sludge generated by this industry are mainly waste lime and pulp residues.
Soft drink waste
In the soft drinks industry, most of the water is used for rinsing containers, equipment, floor washing, etc. Therefore, the waste produced by this industry is low in solids but may have high sugar content (Gendebien et al., 2001).
3.5.9.2. Treatment
Stabilisation of the sludges from the food and drinks industry might be achieved with liming (Gendebien et al., 2001). It is also possible to compost food processing industry sludge, which enables the organic matter to be stabilised, reduces the odour and increases its agronomic value. Anaerobic digestion is also a possibility and is a very effective method for transforming the organic matter in methane, which generates a gas with a high calorific value that can be re-used by the company (Gendebien et al., 2001). This process is frequently used within the food processing industry and significantly reduces the amount of organic carbon from the effluent, producing a minimum amount of sludge.
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3.5.9.3. Contaminants
PTEs
Very few PTEs are found in typical effluent from this industry. Small amounts of PTEs in dyes and inks may enter from packaging and using inks without metals would eliminate this source. Another minor source of PTEs is the inevitable wearing of machinery. Concentrations of metals in sludge and liquid wastes from the animal food production are compiled in Table 3.44. In Table 3.45, concentrations of PTEs in different food and drink industries are also reported.
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Table 3.44 Concentration of PTEs in the animal food production industry Animal food processing Dairy Egg processing Liquid waste Sludge Metals Davis and Rudd, 1999 WRc, 2009 n WRc, 2009 n WRc, 2009 n WRc, 2009 n Mean (min; max) in mg/kg dry weight <0.25 6.1 22.4 64.2 58.2 Cd 143 17 96 52 (<0.25; 0.5) (0.005; 416.7) (0.5; 46.1) (0.14; 1111.1) (0.01; 333.3) 0.4 41.5 222.2 304.2 131.2 Cr 147 17 102 52 (<1.0; 8.9) (0.12; 500) (0.5; 500) (2.48; 1111.1) (0.5; 1040) 2.4 167.8 1272.6 1225.5 912.8 Cu 183 20 112 75 (0.0; 15.8) (0.1; 5866.7) (13.8; 3963.1) (5.6; 7766.7) (0.94; 15680) <0.01 5.4 2.8 7.57 6.41 Hg 138 10 87 48 (<0.01; 0.14) (0.007; 41.7) (0.05; 4.6) (0.003; 111.1) (0.0004; 33.3) 0.3 82.3 546.0 1127.0 817.8 Ni 149 20 112 62 (<1.0; 3.7) (1.6; 1416.7) (100; 1880) (1.7; 4800) (8.2; 2980) 5.8 18.1 34.7 80.8 62.5 Pb 145 20 101 52 (<1.0; 250) (0.06; 416.7) (0.5; 50) (0.98; 1111.1) (0.5; 333.3) 1.7 269.5 1395.9 1612.1 601.0 Zn 184 20 112 75 (0.1; 209.0) (0.5; 5958.3) (7.0 5; 5000) (9.3; 7400) (2.8; 3123.3) n – number of samples
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Table 3.45 Concentration of PTEs in the food and drinks production industry Beverages Baking Vegetable/fruit processing 1Sludge Davis and Rudd, Gendebien et al., Metals WRc, 2009 n WRc, 2009 n WRc, 2009 n 1999 2001 Mean (min; max) in mg/kg dry weight 0.03 271.0 97.4 94.6 0.8 Cd 73 60 196 (<0.25; 1.1) (0.006; 2500) (0.02; 714.3) (0.001; 1428.6) (0.01; 10) 3.2 256.8 180.6 180.8 28 Cr 81 60 203 (<1.0; 78) (0.07; 2500) (0.12; 714.3) (0.1; 1428.6) (0.05; 240) 3.1 1103.9 717.6 1205.3 57 Cu 120 74 235 (0.2; 314.0) (0.06; 9928.6) (2.04; 4020) (0.06; 9928.6) (0.10; 379) <0.02 34.6 12.6 16.9 0.2 Hg 59 46 157 (<0.01; 0. 65) (0.01; 250) (0.02; 71.4) (0.02; 384.6) (<0.01; 8) 2.4 593.8 544.9 604.3 14 Ni 97 66 224 (<1.0; 154) (0.03; 2700) (1.13; 2957.1) (0.14; 6300) (0.10; 154) 1.3 258.0 115.5 106.8 10 Pb 84 60 201 (<1.0; 63) (0.04; 2500) (0.38; 714.3) (0.03; 1428.6) (0.10; 250) 3.7 Se NA NA NA NA NA NA NA (0.35; 6) 9.9 875.6 958.3 673.1 199 Zn 123 74 231 (0.2; 163.0) (0.19; 4075) (0.06; 5000) (0.07; 6200) (0.10; 1815) n– number of samples 1 – not specified from which industry the sludge is from NA – not available
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Organic compounds
Wastes from the food and drink industry are by nature free of contaminants (Davis and Rudd, 1999). Nevertheless, Gendebien et al. (2001) reported concentrations for a range of organic contaminants detected in these wastes. These data are listed in Table 3.46.
Table 3.46 Concentrations of organic contaminants detected in food and drink industry sludge (Gendebien et al., 2001) Organic contaminant Mean (min; max) Fluoranthene 0.2 (0.01; 0.3) Benzo(b)fluoranthene 0.04 (0.01; 0.05) Benzo(a)pyrene 0.04 (0.01; 0.06) ∑ 7 PCBs 0.07 (0.02; 0.21)
Pathogens
The origin and processing of food and drink industry wastes use raw materials that are liable to contain enteric pathogenic bacteria such as Salmonella , E. coli O 157 and Campylobacter spp. In the past, outbreaks of bacterial gastro-enteritis have been blamed to the food industry, such as dried egg, coconut and milk powder, and animal and fish meals (Davis and Rudd, 1999). Waste food that has been cooked can be assumed to be pathogen free but only immediately after production since the potential for recontamination by enteric pathogens is possible if the wastes are allowed to be browsed by rodents and scavenging birds (Davis and Rudd, 1999).
Food and drink industry wastes can also contain plant pathogenic organisms. In particular potato nematode cysts, which constitute a major pest for potato crops, are endemic in Europe and can be in the effluent discharged from vegetable processing factories. Water and soil sediment from potato starch and sugar factories may contain cysts and spread the pests if landspread. Beet necrotic yellow vein virus (BNYVV) is a causal agent of rhyzomania in sugar beet and could potentially occur in the sludge receiving discharges from infected crops (Gendebien et al., 2001).
Wastes from the brewery and distillery industry can be considered pathogen free because of the processes to which they have been subjected. Those from preparation of fruit juices and soft drinks are pathogen free due to their acidity.
3.5.10. Waste from chemical and pharmaceutical manufacture
3.5.10.1. Introduction
Chemical and pharmaceutical manufacture waste is sludge from the biological synthesis of chemicals and pharmaceuticals, respectively. The chemical and pharmaceutical industry covers a wide range of industries such as ammonia, ammonium sulphate and gelatine production (Gendebien et al., 2001).
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Wastes produced in the pharmaceutical industry are mainly biomass, which are cells from the fermentation process, synthesis residues, alcohol and organic solvents from the cleaning processes, product residues and dust from reprocessing. Pharmaceuticals are produced using synthesis or fermentation. Wastes generated by synthesis are generally synthesis residues and solvents, whereas wastes generated by fermentation are typically biomass and fermentation liquid (Gendebien et al., 2001). Of these wastes, fermentation residues are the most likely to be landspread since the biomass breaks down in the soil providing nutrients for plant growth.
Large volumes of waste are produced by the chemical industry, some of them with agronomic benefits if landspread. These include waste ammonia, ammonium sulphate and wastes from the manufacture of fertilisers. The quality of these wastes is very variable and in some countries their application to land is not allowed. Some of these wastes contain nutrients that are beneficial to plant growth, such as ammonium and ammonium sulphate that have very high nitrogen content. These wastes should therefore be applied to land at very low rates.
3.5.10.2. Treatment
Depending on the nature and origin of the waste, they can be treated by stabilisation via digestion or composting or addition of lime or a controlled pasteurisation process (Gendebien et al., 2001).
3.5.10.3. Contaminants
PTEs
PTEs may be added as ingredients for the product, e.g. mineral supplements, or may enter from catalysts. The raw animal, plant and fungi material could introduce PTEs and this can be controlled as described in the previous section on livestock manure. Concentrations of PTEs in different wastes from the chemical and pharmaceutical industry are presented in Table 3.47.
Table 3.47 Concentrations of PTEs in wastes from the chemical and pharmaceutical industry (Gendebien et al., 2001) Type of waste Ammonium Gelatine Metals Pharmaceutical Ammonia sulphate production Mean (min; max) in mg/kg dry weight Cd <0.25 0.2 (<0.25; 1) <0.25 1.3 (0.7; 2.5) Cr <1.0 3 (<1.0; 25) <1.0 14 (6; 37) Cu 3.5 (0.0; 13) 4 (<1.0; 18) 0.6 (<1.0; 2.2) 17 (4; 45) Hg <0.01 <0.01 0.1 (<0.01; 0.6) 1.3 (0; 10) Ni 0.5 (<1.0; 3.4) 0.3 (<1.0; 1.7) <1.0 (<1.0; 1.0) 14 (1; 39) Pb <1.0 2 (<1.0; 19) <1.0 12 (2; 22) Zn 6.3 (0.5; 19.5) 5 (<1.0; 18) 0.9 (<1.0; 2.8) 411 (92; 1178)
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Organic compounds
A large variety of organic contaminants may be present depending on what is being produced. The waste of most interest for land spreading is that of ammonia types from fertiliser manufacture, and waste from the fermentation process in pharmaceutical primary process (Gendebien 2001). Particular care needs to be taken when biomass originates from antibiotic production. Most antibiotics are removed during the extraction process but the sludge might still contain traces. Therefore, antibiotics remaining in the waste may have adverse effects on soil microorganisms that could result in dissemination of resistance to antibiotics in the long term. Organic chemical entry is tightly controlled in this industry to ensure the exact content of the product. Research into alternative pharmaceuticals and chemical treatments provide new information about less persistent chemical options. This is achieved through Green chemistry techniques, environmental risk assessment and use of REACh data (Clark 2006).
Pathogens
Pathogens are present in animal, plant and fungi raw material waste. As discussed in previous sections, pathogens have diffuse sources that are not controllable. They enter the process with raw material but will be eliminated as waste before reaching the primary and secondary processing stages to avoid contamination of the product. It is possible that pathogens are present at later stages for testing the product if appropriate.
3.6. Inorganic wastes
Inorganic wastes arising from industry and considered in this section are: decarbonation sludge; sludge from the production of drinking water; waste lime, lime sludge and waste gypsum.
Soil pH and Liming
In soils, the pH is very important for optimal plant development and agricultural crop production. A range of factors, including soil type, soil structure, rainfall, and the agricultural production system influences soil pH. Soil pH tends to decrease due to rainfall and the removal of elements by crop production and harvesting. Therefore, it is important to maintain soil pH. This is done by regularly adding basic elements such as calcium and magnesium as liming materials.
When evaluating a lime product there are two important factors:
The Total Neutralising Value (TNV) The total neutralising value of a lime product is determined by comparing the neutralising value of the product to the total neutralising value of pure calcium carbonate, which has a value of 100. The ground limestone (calcium carbonate) is the most common form of lime
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sold and has a TNV of 90%. The standard for licensed ground limestone products is a TNV greater than 90% (Gendebien et al., 2001).
The fineness There is also a standard of fineness for licensed ground limestone products to guarantee the good efficacy of the TNV. The standard for licensed ground limestone products is a fineness of 100% through a 35 mm sieve and 35% through a 0.15 mm sieve. The fineness and uniformity of the fineness of the product has a direct impact on the ability to spread the product evenly and guarantee its solubility. A finer material will react faster with the soil than a product that has large particle sizes (Gendebien et al., 2001). Lime application is of agronomic benefit in regions with acid or neutral soil.
3.6.1. Sludge from the production of drinking water
3.6.1.1. Introduction
Following the treatment of raw water for the production of drinking water, the residue arising is sludge, which is composed of impurities removed and precipitated from the water together with the residues from any chemical treatment used.
Waterworks sludge can be classified either as a coagulant, natural, groundwater or softening sludge (Gendebien et al., 2001). Typically, surface water is treated by chemical coagulation and rapid gravity filtration, which produces aluminium or ferric sludge if aluminium and iron are used as the coagulant chemical. Therefore, coagulant sludge has a gelatinous appearance and contains high concentrations of aluminium or iron salts with a mixture of organic and inorganic materials and hydroxide precipitates. Natural sludge or slow sand sludge results from the washing of slow sand filters. Softening sludge resulting from the softening of hard waters mainly contains calcium carbonate and magnesium hydroxide precipitates with some organic and inorganic substances.
Waterworks sludge does not contain any obvious attributes that could be associated with agricultural benefit. Therefore, spreading of these wastes to agricultural land or other land is potentially a major disposal route. Nevertheless, in some circumstances, there might be an agricultural benefit since waterworks sludge can contain sulphur, trace elements and small amounts of organic matter. Benefits resulting from the application to land of coagulant sludge are not easily demonstrated. Softening sludge can be used for liming of agricultural land. Natural sludge or slow sand sludge may contain enough organic matter with organically bound nutrients that makes them beneficial for agricultural land (Gendebien et al., 2001).
The application of waterworks sludge to land raises some concerns about the potential adverse effects on plant growth, concentrations of PTEs and aluminium and possible contamination of surface or groundwaters. Accumulation of aluminium or iron due to extended applications of sludge is not likely to cause problems, especially if the soil pH is above 6.0. Nevertheless, in Scotland, concerns were raised that aluminium rich sludge applied to acidic soils could have deleterious effects on the growth of barley, particularly if soil pH falls below 5.5 (Gendebien et al., 2001). Accumulation of iron in the topsoil of The Food and Environment Research Agency 97
pasture land, after application of sludge from drinking water treatment plants, could have deleterious effect on the copper metabolism of grazing animals, especially sheep. It has been reported that aluminium and iron hydroxides in coagulant sludges can adsorb soluble phosphorus and thus reduce its availability to plants and affect plant growth. However, if necessary, the co-application of this sludge with sewage sludge or the addition of supplemental phosphorus to the soil would eliminate this effect (Gendebien et al., 2001).
The application of sludge from drinking water treatment plants to forest land has been investigated in several countries. In one USA study, liquid alum sludge has been applied to deciduous and coniferous forested land, and after one year it was concluded that no adverse effects on tree growth or nutrient uptake occurred in the short term. However, trees grow slowly and thus measurements need to continue for many years before conclusions can be drawn (Dillon, 1997).
Land reclamation could also be a significant disposal route for waterworks sludge. Potential benefits of using sludge from drinking water treatment include the pH buffering capacity, soil conditioning properties and capacity to adsorb metals (Gendebien et al., 2001).
3.6.1.2. Contaminants
PTEs
The quality of the sludge will depend on the type of treatment used. If low-grade coagulant chemicals are used, the sludge might be contaminated with PTEs . Concentrations of PTEs in sludge generated from drinking water production were obtained from WRc (2009) and are listed in Table 3.48.
Table 3.48 Concentrations of PTEs in sludge from waterworks in mg/kg dry weight (WRc, 2009) Metal Mean (min; max) n Cd 56.6 (0.0005; 5917.2) 107 Cr 1077.3 (0.01; 112 426) 107 Cu 2374.7 (0.001; 242 603) 107 Hg 17.4 (0.000002; 1775.1) 105 Ni 1302.5 (0.02; 118 343) 106 Pb 1997.6 (0.005; 207 101) 107 Zn 9590.3 (0.03; 994 082) 107
Organic compounds
The formation of AOX has been reported following drinking water disinfection by both chlorination and ozone. These disinfection processes may lead to the formation of trihalomethanes with bromine derivatives also formed if bromine is present in the water (Erhardt and Prüeß, 2001). However, concentrations of organic compounds in sludge arising from the preparation of drinking water have not been found. The Food and Environment Research Agency 98
Pathogens
There is a possibility that sludge from drinking water treatment plants can contain pathogens such as Cryptosporidium , which can be removed from the raw water at the treatment plant.
3.6.2. Decarbonation sludge
3.6.2.1. Introduction
In power stations, boilers that use hot water need a conditioning system to treat cubic meters of water coming from river, ground water or spring. The soluble residues, such as calcium and magnesium bicarbonates, present in the water make it hard, which affects pipes and the boiler durability. Therefore, a process of chemical precipitation is used to reduce hardness from the water, known as “lime softening”. This process causes soluble salts to become insoluble and then they are removed by sequential sedimentation. Lime is predominantly used for maintaining the pH value at the ideal range for the precipitation of decarbonation sludge. Other processes might also be used to precipitate soluble salts from water and those influence the size of the carbonate particles and reactivity of this lime with the soil. In some installations, the precipitation is performed on a sandy substrata and gives small granulates of carbonate that have very low reactivity with the soil.
The origin of the water used in the boiler influences sludge quality. Therefore, if the water is from canal or river in industrial zones it may contain hydrocarbons and heavy metal residues, whereas no problems arise if it is ground water (Gendebien et al., 2001).
In decarbonation sludge, the only significant elements obtained are calcium and magnesium. The agronomic value of this waste is the benefit that calcium adds to the soil and agricultural crop production. In analysis carried out, the total neutralising value of the decarbonation sludge cakes at 60% dry matter was 30% total neutralising value.
3.6.2.2. Treatment
A dewatering system is required to dry the sludge. The dewatering process highly influences the dry matter content. A mechanical dewatering process using a belt press generates calcium cake at approximately 55 to 60% dry solid content that has a good stability on land. However, other systems might generate calcium cake with a dry matter content of 15 to 20%, which can cause storage problems (Gendebien et al., 2001).
3.6.2.3. Contaminants
PTEs
Metal (as PTEs) content from decarbonation sludge is presented in Table 3.49 and this data is mainly for Belgium. The Food and Environment Research Agency 99
Table 3.49 Concentration of PTEs in decarbonation sludge in mg/kg dry weight (Gendebien et al., 2001) Metal Mean (min; max) Cd 0.2 (0.07; 0.9) Cr 11 (0.7; 26) Cu 9 (0.6; 20) Hg 0.06 (0.01; 0.16) Ni 10 (0.8; 32) Pb 16 (0.8; 36) Zn 51 (9; 110)
Organic compounds
When water is pumped from canal or river from industrial zones it may contain hydrocarbons (Gendebien et al., 2001). However, no information has been found on concentrations of organic compounds in decarbonation sludge.
Pathogens
Due to the high pH of lime sludge, these sludges are expected to be pathogen free.
3.6.3. Waste lime and lime sludge
3.6.3.1. Introduction
The two biggest producers of waste lime are cement manufacture and gas processing (Davis and Rudd, 1999).
Waste lime from cement manufacture consists of cement kiln dust, which is a mixture of calcium carbonate and calcium oxide. Other wastes might also be produced but in much lower amounts (Davis and Rudd, 1999). Advantages for the landspreading of these wastes are mostly due to their liming value. Neutralizing values typically range from 20 to 40% and vary with the moisture content of the material (Davis and Rudd, 1999). Application rates for these wastes are usually low and should be based on the neutralizing value. Soil pH should be determined before landspreading since agricultural benefit is only achieved if the land has lime requirements. Potential disadvantages may arise from the fact that cement kiln dusts are likely to contain residues from the combustion of materials used to generate the high temperatures required for the manufacturing process. Waste lime from gas processing is produced from the production of acetylene gas. This waste lime contains a high percentage of calcium hydroxide, which makes it a high quality amendment material due to its high neutralizing value. Other nutrients and other contaminants may be present in this waste but levels are dependent on the nature of the production process (Davis and Rudd, 1999). The production of acetylene gas involves the reaction of calcium carbide with water, with the production of lime as a by-product. Other The Food and Environment Research Agency 100
compounds are also produced, such as thiourea, for which consequences of landspreading is unknown (Davis and Rudd, 1999).
3.6.3.2. Contaminants
PTEs
PTEs are present in liming materials and other inorganic fertilizers (e.g. nitrogen, phosphate, potash). Reported levels of metals in waste lime and sludge lime from cement manufacture and gas processing are compiled in Table 3.50.
Table 3.50 Concentration of PTEs in waste lime and lime sludge (mg/kg dry weight) Lime sludge Metal Davis and Rudd, 1999 WRc, 2009 Mean (min; max) Mean (min; max) n Cd 1.0 (<0.25; 8.0) <0.25 (<0.25; 2.47) 1.0 (0.37; 1.8) 6 Cr 10.7 (0.5; 31.5) 38.5 (<1.0; 614) 17.1 (7.95; 33) 6 Cu 12.7 (0.3; 46.0) 9.9 (0.4; 26.2) 46.8 (8.8; 180) 6 Hg 0.5 (0.5; 3.5) <0.01 (<0.01; 0.02) 0.18 (0.005; 0.5) 6 Ni 5.8 (0.1; 25.0) 3.0 (0.7; 8.5) 8.9 (7.6; 11.2) 4 Pb 145 (0.0; 1000) 1.2 (<1.0; 6.97) 29.7 (4.8; 89) 6 Zn 44.4 (0.2; 153.0) 35.9 (2.1; 270.0) 47.9 (17; 96) 6
Organic compounds
Depending on the manufacture process, cement kiln dusts are likely to contain residues from the combustion of materials used to generate the high temperatures required. Some cement manufacturers have recently started to use waste organic solvents as fuel sources for these processes and thus organic residues may occur in kiln dust (Davis and Rudd, 1999).
Pathogens
Due to their high pH, ranging from 10 to above 12, lime sludge and waste lime is self- disinfecting, as long as the pH is maintained. Therefore, these wastes are inherently pathogen free.
3.6.4. Waste gypsum
3.6.4.1. Introduction
Gypsum is a mineral (hydrated calcium sulphate) that is used in the preparation of plaster and plaster-based building materials. Industrial gypsum is a by-product from the manufacture of phosphoric acid (phosphogypsum), from the neutralisation of sulphuric acid in many chemical processing industries (waste acid neutralisation gypsum), from the
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capture of sulphur dioxide in the flue gases of fossil-fuel powered generators (flue gas desulphurisation gypsum) and from salt extraction (Davis and Rudd, 1999).
Gypsum should be analysed for calcium, sulphur and potentially toxic elements. Depending on the results, applications of gypsum as soil conditioner can be made to heavy land (high clay content), or to sulphur deficient land in accordance to crop requirements for this nutrient. Excessive additions of sulphur to land can lead to copper deficiency in livestock (Gendebien et al., 2001).
The use of gypsum as a soil conditioner is well known. Gypsum is used to restore the structure of saline sodic soils, especially those affected by flooding from seawater. Gypsum is also beneficial in less extreme cases, where poorly structured clays can be improved on a long term by additions of gypsum. There is little, if any, structural benefit from adding gypsum to very light soils such as sands and loamy sands (Davis and Rudd, 1999). Gypsum also contains large amounts of sulphur, which can be as high as 20% depending on the purity of the product. Many agricultural soils are becoming sulphur deficient due to reductions in atmospheric depositions of sulphur in acid rains and as such sulphur containing fertilisers are increasingly being used (Davis and Rudd, 1999). Recently, following the application of gypsum, unexpected improvements in crop yields occurred that may have resulted from correction of sulphur deficiency that have not been previously diagnosed.
The presence of other plant nutrients is dependent on the process from which the material is derived, and gypsum wastes can also contain quantities of phosphate that also have an agronomic value.
Acid neutralisation gypsum
Large volumes of sulphuric acid waste are produced from a wide range of industrial processes. The acid is used for the extraction of a range of chemical compounds, especially for the extraction of mineral ores. As a consequence, the acid contains many different contaminants derived from the primary raw materials that can be carried over in the neutralisation process and therefore present in the gypsum produced.
Flue gas delphurisation gypsum
Flue gas desulphurisation (FGD) gypsum is produced primarily to remove sulphur dioxide in flue gases. Benefits from the application of fuel gas sulphurisation are similar to other sources of high purity gypsum. However, gypsum from this source does not usually contain other beneficial nutrients.
3.6.4.2. Contaminants
PTEs
Contamination from metals is common in gypsum due to the use of strong acids used in mineral based industries that will also extract metals (Gendebien et al., 2001). The majority of FGD gypsum is produced from coal-fired power stations and thus contains a range of The Food and Environment Research Agency 102
metals as well as combustion products. Concentrations of PTEs in waste gypsum from plasterboard are presented in Table 3.51. No data has been found for metals in acid neutralisation gypsum.
Table 3.51 Concentration of PTEs in waste gypsum from plasterboard (mg/kg dry weight) 1Davis and Rudd, 1999 WRc, 2009 Metals Mean (min; max) n Cd 1.4 (0.1; 5.0) 0.02 1 Cr 51.0 (1.6; 466.0) 21.6 1 Cu 12.0 (1.2; 31.8) 4.41 1 Hg 0.1 (0.0; 0.2) 0.05 1 Ni 32.5 (1.0; 144.0) 10.58 1 Pb 53.0 (1.3; 404.0) 2.03 1 Zn 124.0 (2.4; 1075.0) 8.51 1 1- no data from where the gypsum is coming from
Organic compounds
FGD gypsum is produced to remove sulphur dioxide in flue gases. Therefore, other contaminants might be adsorbed in the flue gases and the nature of these contaminants is dependent on the fuel used in the combustion process. Gypsum derived from the burning of other materials may contain complex organic compounds. However, a detailed description of potential contaminants in gypsum is not possible due to the wide range of different industries (Davis and Rudd, 1999). No data has been found for organic compounds in gypsum.
Pathogens
As in the production of lime, heat is used to prepare plaster and therefore it is a disinfected product and inherently free of pathogens (Davis and Rudd, 1999).
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4. CONTAMINANT LOADINGS FROM APPLICATION OF MATERIALS ONTO LAND
4.1. Introduction
The previous section only collated information on the occurrence of different contaminants in different waste types. To quantify the importance of different waste types in term of potential for soil contamination, information on the application rate of the individual waste materials and concentrations of contaminants in the different materials are needed.
In this section, levels of contaminants from different materials that were compiled in the previous chapter are used together with the application rates that are summarised in Table 4.1. The input from each contaminant to land (g/ha) for different materials is calculated by multiplying the concentration of the contaminant (mg/kg) by the application rate (tonnes/ha). Care needs to be taken when using concentrations of contaminants on a dry/fresh weight basis with application rates on the same basis. If information on the dry matter content is available then data on a fresh weight basis can be converted to dry weight basis. For livestock manures, input of contaminants were based on the maximum application rate of 250 Kg N/ha per year. Nitrogen equivalents for different livestock manures were obtained from Fiona Nicholson (pers. communication).
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Table 4.1 Application rates of materials to land used to calculate input of contaminants Dry solids Material Tonnes/ha Content (%) Sewage sludge 6.5 DW NA Livestock manures (based on an application rate of 250 kg N/ha) Dairy slurry 69.4 FW 10 Dairy FYM 41.7 FW 25 Beef slurry 69.4 FW 10 Beef FYM 41.7 FW 25 Pig slurry 56.8 FW 6 Pig FYM 35.7 FW 25 Sheep FYM 35.7 FW 25 Layer manure 13.2 FW 35 Broiler litter 8.3 FW 60 Compost Green compost 33 FW 60 Green/food compost 23 FW 60 Digestate 30 FW 3.5 Drinking water preparation sludge 102 FW NA Paper waste Primary treated 69 FW 42.6 Biologically treated 33 FW 27.5 Physico -chemically treated 69 FW 39.8 Abattoir waste Blood 69 FW NA Gut contents 55.5 FW NA Wash waters 134 FW NA Textile waste Sludge 18 FW NA Wool scourers 15 FW NA Food and drinks Beverages 150 FW NA Baking 128 FW NA Vegetable processing 158 FW NA Animal food production- egg 193 FW NA processing Animal food production- dairy 132 FW NA Meat processing - liquid 215 FW NA Meat processing - sludge 143 FW NA Waste lime and lime sludge 60 FW NA Gypsum from plasterboard 20 FW NA Dredgings 753 FW 48 FYM – farmyard manure DW – dry weight FW – fresh weight
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For each contaminant, the loading to soils from different materials for which data is available is presented in column graphs for comparison. Different classes of materials are represented by different colours. At the end of each contaminant section a discussion is presented.
At the end of this chapter, a summary table is presented showing the relevance of contaminants for each material.
4.2. Contaminants
4.2.1. PTEs
In Figure 4.1, the total metal content, i.e. sum of Cd, Cr, Cu, Ni, Pb, Zn and Hg, loading from materials that are applied to land is shown.
Figure 4.1 Total metal input following the application of different materials
Individual PTEs loading from different materials and respective sources are presented for cadmium (Fig. 4.2), chromium (Fig. 4.3), copper (Fig. 4.4), nickel (Fig. 4.5), lead (Fig. 4.6), zinc (Fig. 4.7), and mercury (Fig. 4.8).
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The input of PTEs following the application of dredging to soils is separately considered since concentrations of PTEs are much higher than inputs from any other materials (Fig 4.9). Input of PTEs following application of sewage sludge is presented in the same graph for comparison.
At the end of this section, a summary table (Table 4.9) of heavy metal input following the application of different materials to land and comparison with input from sewage sludge is presented.
Figure 4.2 Loading in g/ha following application of different materials to soils - Cadmium
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Figure 4.3 Loading in g/ha following application of different materials to soils - Chromium
Figure 4.4 Loading in g/ha following application of different materials to soils - Copper
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Figure 4.5 Loading in g/ha following application of different materials to soils - Nickel
Figure 4.6 Loading in g/ha following application of different materials to soils - Lead
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Figure 4.7 Loading in g/ha following application of different materials to soils - Zinc
Figure 4.8 Loading in g/ha following application of different materials to soils - Mercury
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Figure 4.9 PTEs loading in g/ha following application of dredgings or sewage sludge to soils
Discussion
With the exception of dredgings, when considering the total input of PTEs, loading following the application of sewage sludge is still greater than any other material. A similar loading of PTEs is obtained following the application of composts, drinking water preparation sludge and meat processing liquid (Figure 4.1). Loadings of PTEs following the application of dredging are greater for all individual or total amount of metals than inputs from any other materials (Figure 4.9).
When considering individual PTEs, with the exception of copper and zinc in pig slurry and farmyard manure, livestock manures represent a much lower input of metals than sewage sludge. Copper and zinc loading from pig slurry and farmyard manure is greater than for the other livestock manures but still represent a lower input than sewage sludge. Loading of copper similar to sewage sludge loadings are found following application of biologically treated paper waste, egg and meat processing (Figure 4.4). With the exception for dredging, chromium and zinc inputs from sewage sludge are greater than for any other material (Figures 4.3 and 4.7). With the exception for lead, compost loadings of PTEs are very similar to inputs from sewage sludge. Input of lead is much higher from composts than from sewage sludge. Greater inputs of nickel are found for meat processing (liquid and sludge), egg processing and drinking water preparation sludge. Cadmium inputs are greater for waste lime and lime sludge, green compost, and food and drink wastes than loadings from sewage sludge application. Loadings of mercury are unknown for a range of materials. Nevertheless, inputs following the application of gypsum from plasterboard are greater than inputs from sewage sludge. Similar mercury inputs are from green composts and food and drinks wastes (Table 4.9). The Food and Environment Research Agency 111
Table 4.2 Heavy metal summary input following the application of different materials to land. Comparison with sewage sludge inputs. Material Cd Cr Cu Ni Pb Zn Hg SUM Sewage sludge heavy metal mean 10 680 2025 240 900 4960 6.7 8820 loading (g/ha) Livestock manures Dairy slurry << << < << << << NA << Dairy FYM << << << << << << NA << Beef slurry << << << << << << NA << Beef FYM << << << << << << NA << Pig slurry << << < << << < NA < Pig FYM < << < << << < NA < Sheep FYM << << << << << << NA << Layer manure << << << << << << NA << Broiler litter << << << << << << NA << Compost Green compost > < < = >> < = = Green/food compost = < < = >> < < = Digestate << << << << << << NA << Drinking water preparation sludge > < < >> < < < = Paper waste Primary treated NA < < << << << NA < Biologically treated = < = = < < NA < Physico-chemicallly treated NA < < << << < NA < Abattoir waste Blood = << < = << << << << Gut contents << << << << << << << << Wash waters << << << << << << << << Textile waste Sludge << << << << << < << < Wool scourers << << << << << < << < Food and drinks Beverages >> << << < << << = << Baking >> << << = << << = << Vegetable processing >> < < > << << = < Animal food production- egg >> << = >> << << << < processing Animal food production - dairy = << << < << << < << Meat processing - liquid >> = = >> << < < = Meat processing - sludge >> < < >> << << < < Waste lime and lime sludge >> < << = << << << < Gypsum from plasterboard << < << << << << >> << Dredgings >> >> >> >> >> >> >> >> << much lower < lower = similar > higher >> much higher
4.2.2. Organic compounds
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With the exception of selected classes of organic compounds in sewage sludge, data on organic compounds in materials applied to land is very scarce. In some cases a sum of organic compounds concentrations are given, whereas in others only concentrations for individual compounds are available (e.g. PAHs). Some organic contaminants are only relevant for some materials (e.g. veterinary medicines are only relevant for livestock manures). An important factor also to be taken into account is that the usage of organic compounds such as PAHs and PCBs has significantly decreased over the last decades and PCBs have been banned. Therefore, the use of older data is not likely to be relevant today.
Because of these factors, data on contaminants from which inputs can be quantitatively comparable from different wastes is only available for PAHs and PCBs. Therefore, organic compounds loading from different materials and respective sources are only discussed for PAHs (Figures 4.10 and 4.11, Table 4.10) and PCBs (Figures 4.12 and 4.13, Table 4.11). At the end of this section a general discussion on the persistence of organic contaminants is presented and then a more detailed discussion on organic compounds in sewage sludge, composts and livestock manures is also presented.
In Figure 4.10, loading of a sum of 16 PAHs following the application of sewage sludge, pulp and paper sludge and composts compliant with PAS 100 (BSI, 2005) are presented. Loadings of PAHs are greater from the application of sewage sludge than from the application of composts or paper sludge.
Figure 4.10 PAH loading in g/ha following application of materials to soils
*
* value shown represent maximum mean PAH
For other materials, such as abattoir waste, textile waste and food and drink sludge, only applications based on a fresh weight basis are available, whereas concentrations of PAHs are on a dry matter basis. Also for all these materials concentrations are for an individual The Food and Environment Research Agency 113
compound and not for a sum of PAHs. Nevertheless, loadings of PAHs for these materials can still be compared but it is not possible to compare with inputs from sewage sludge and composts.
Figure 4.11 PAH loading in g/ha following application of materials to soils
**
*
** **
Note: application rates for abattoir waste, textile and food drink sludge are on a fresh weigh basis. If corrected for a dry weight basis values would be lower *Maximum loading for one PAH (benzo(a)pyrene) **Results only available for one PAH (fluoranthene): - textile sludge and food and drink sludge values represent mean - textile - wool scourers value represent maximum value
In Figure 4.12, loading of a sum of 7 PCBs following the application of sewage sludge and composts compliant with PAS 100 (BSI, 2005) are presented. Loadings of PCBs are greater from the application of composts than from the application of sewage sludge.
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Figure 4.12 PCBs loading in mg/ha following application of different materials to soils
As for the quantification of PAHs in different materials, for abattoir waste, textile waste and food and drink sludge, only applications based on a fresh weight basis are available, whereas concentrations of PCBs are on a dry matter basis. Nevertheless, loadings of PCBs for these materials can still be compared but it is not possible to compare with inputs from sewage sludge and composts (Figure 4.13).
Figure 4.13 PCB loading in mg/ha following application of materials to soils
*
Note: application rate for abattoir waste, textile and food drink sludge are on a fresh weigh basis. If corrected for a dry weight basis values would be lower (depends of dry matter content) * Maximum loading for PCBs The Food and Environment Research Agency 115
4.2.3. Pathogens
Concentrations of pathogens in different material types that are applied to land are not available. Nevertheless, the likelihood of pathogens in different materials can be assessed and is presented in Table 4.3.
Table 4.3 Qualitative assessment of pathogens levels in materials applied to land Material type Pathogens lev el Controls applied Sewage sludge Unlikely Yes (legislation) Septic tank sludge High (if not treated) No Livestock manures High (if not treated) No Compost Low Yes (voluntary) Digestate Low Yes (voluntary) Pulp and paper industry sludge Unlikely No Waste wood, bark and other plant material Low No Dredging from inland waters Low No Abattoir wastes Medium No Textile waste Unlikely No Tannery and leather waste Unlikely No Waste from food and drinks preparation Low No Waste from chemical and pharmaceutical Unlikely No manufacture Waste lime and lime sludge Unlikely No Waste gypsum Unlikely No Decarbonation sludge Low No Drinking water production sludge Possible No
Discussion
For most other contaminants and waste types, data on concentrations are limited do it is not possible to establish, in a quantitative way, the likely input rates to land. However, for many contaminants, qualitative information that can be used to provide a guide as to which waste material type is most important for a particular contaminant is available. For example, it is known that veterinary medicines are only used in animal farming and that the main route of input to land will be via the application of manure or slurry to land. The results of this more qualitative assessment are presented in Table 4.4.
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Table 4.4 Summary of the input of contaminants following the application of different wastes Contaminants Material Bulk industrial and Human Veterinary Biocides Metals POPs Pesticides Pathogens domestic chemicals pharmaceuticals medicines and PCPs Sewage sludge ++ ++ + + ++ NR ++ unlikely Septic tank sludge ++ + + + ++ NR ++ ++ (if untreated) Livestock manures + + + + NR ++ NR ++ (if untreated ) Compost + + + + NR NR NR + (low) Digestate + + + + NR NR NR + (low) Pulp and paper industry sludge + + + NR NR NR + unlikely Waste wood, bark and other plant + + + + NR NR + + (low) material Dredgings ++ ++ ++ + + + + + (low) Abattoir waste + + + + NR + NR + (medium) Textile waste + + + + NR NR + unlikely Tannery and leather sludge + + + + NR NR + unlikely Waste from food and drinks + + + NR NR NR NR + (low) preparation Waste from chemical and + + + NR + + + unlikely pharmaceutical manufacture Waste lime and lime sludge + + + NR NR NR NR unlikely Waste gypsum + + + NR NR NR NR unlikely Decarbonation sludge + + + NR NR NR NR + (low) Drinking water preparation sludge + + + NR NR NR NR possible NR – not relevant + relevant ++ one of the major sources
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5. IDENTIFICATION OF POSSIBLE STRATEGIES TO REDUCE CONTAMINATION OF MATERIALS SPREAD TO LAND
5.1. Introduction and approach used
In this section, the aim is to identify potential upstream control measures for reducing contaminants in waste streams that can be landspread. This was achieved by: 1. Identifying major sources for contaminants in materials that are landspread using information from the previous section (section 4). 2. Identifying upstream control measures that would reduce contamination of the waste streams. 3. Using information from previous sections to try to identify potential treatments to eliminate contaminants from waste streams. 4. Identifying the most effective measures from 2 for reducing the levels of contaminants in the waste streams without compromising the benefits to soil.
Effective measures are those that are practical, do not cause further contamination or inhibition of treatments, and that might be applied as a control measure at the source to reduce levels of contaminants in the final material and thus minimise the need for treatment.
In order to identify strategies to reduce inputs of contaminants, eleven waste streams were identified and studied:
1. Sewage sludge 2. Livestock manure 3. Municipal solid waste 4. Paper and pulp waste 5. Wood, bark and other plant waste 6. Dredging from inland waters 7. Abattoir waste 8. Textile industry waste 9. Tannery and leather waste 10. Waste from food and drinks preparation 11. Waste from basic organic chemical and pharmaceutical companies
Information was gathered for each production process and the waste generated by it. This was translated into ‘the waste production processes’. The processes for each waste stream are briefly described and illustrated with a diagram to show the path of the contaminants to land. The diagrams divide into 5 sections:
Contaminants – all contaminant groups are shown and those relevant to the waste type are filled in white. Source – these are the raw materials or entry stages into the waste stream. Production – these are the sludges resulting from processes in the manufacturing system.
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Processing – are the post manufacturing system treatments to turn the waste product or sludge into a useable biosolid for land application, e.g. composting. Use – landspreading.
A literature review was undertaken to identify techniques to eliminate, reduce, or treat contaminants found in the processes. Where information was unavailable, the opinion and judgment of this report’s authors has been used to suggest a control measure. Traces of all contaminants are possible in all waste streams. However, these might be so small that they are not of concern in the final material.
The practicality and effectiveness for each upstream control measure has been judged from low to high. Table 5.1 shows a description and examples of judgments made.
Table 5.1 Judgment for practicality and effectiveness Practicality Description Example Low Non -practical Several years of research needed Medium Possible to apply Not too much effort to apply High Easy to apply Already available Effectiveness Description Example Low Not very effective Represents only small proportion of contamination Medium Effective Some reduction of contamination High Very effective Substitution of chemicals
At the end of each waste stream section, contaminants of concern for each contaminant type and their major source have been included and possible upstream control measures have been proposed. In these tables the strategies judged most effective for each contaminant are presented in bold. The judgement was made from the available information in previous sections and the following statements: 1. No contamination is most preferable (taking the view that over long periods of time persistent contaminants accumulate even if only applied in small quantities). 2. The elimination and substitution of persistent contaminants at the source is more efficient than removing them later in the process. 3. No measure should cause further contamination or inhibit later treatments. 4. No measure should be excessively expensive or complex.
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5.2. Sewage Sludge
Sewage sludge is the residue collected following treatment of waste water. Sewage derives from domestic sources and small businesses, runoff, diffuse sources and storm drain overflow, and industry treated waste. Figure 5.1 illustrates the path of contaminants from sewage sludge to land. The nature of sewage treatment concentrates contaminants into the sludge so that the effluent can be released safely into water bodies and is regulated by the Urban Waste Water Treatment Directive (EC, 1991b).
Figure 5.1 Sewage sludge waste stream
Contaminant Organic contaminants
POPs POPs Bulk Chemical Pharma- ceuticals Veterina- rydrugs Pesticide s /Biocides personal care products Pathogen PTEs PTEs
Source
Domestic Urban runoff Commercial
Production
Primary Secondary Tertiary Treatment Treatment Treatment
Sludge
Processing
Compost Anaerobic Advanced digestion treatments
Use
Land Application
5.2.1. Potentially toxic elements
5.2.1.1. Sources
The presence of PTEs in sludge is due to domestic, road-runoff and industrial inputs to the urban wastewater collection systems (IC Consultants, 2001). Major sources of emission of PTEs to urban wastewater have usually been from industrial sources (IC Consultants, 2001). However, more stringent controls to industry have significantly reduced the levels of PTEs into urban wastewater (Gendebien et al., 1999). Domestic sources of PTEs are presented in Tables 5.2 and 5.3.
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Domestic sources for PTEs
In domestic wastewater, faeces contribute 60 to 70% of the load of Cd, Zn, Cu and Ni and above 20% of the input of these metals are from mixed water from domestic and industrial sources. Major sources of metals in faeces are from food products and supplements, since metals and other elements may enter the food chain from growth and harvesting through to storage and processing. Furthermore, certain food groups can accumulate some elements. For example, fish and shellfish are known to accumulate As and Hg, while cereals can accumulate Cd (FSA, 2004). The other main sources of metals in domestic wastewater are from personal care products, pharmaceuticals, cleaning products and liquid wastes. The main source of Cu in hard water areas is from plumbing, contributing more than 50% of the Cu load and Pb inputs equivalent to 25% of the total load of this element have been reported in districts with extensive networks of Pb pipework for water conveyance (IC Consultants, 2001).
Table 5.2 Domestic sources of metals/elements in wastewater (IC Consultants, 2001) Metal/element Sources Arsenic inputs come from natural background sources and from household products such as washing products, medicines, garden products, wood preservatives, old paints and pigments Arsenic Arsenic is present mainly as DMAA (dimethylarsinic acid) and as As (III) (arsenite) in urban effluents and sewage sludge (Carbonell -Barrachina et.al ., 2000). Cadmium is mainly found in rechargeable batteries for domestic use (Ni-Cd batteries), in paints and in photography. The main sources in urban wastewater are from a wide range of sources such Cadmium as food products, bodycare products, detergents and storm water. In food products the main source of Cd is likely to be the use of phosphate fertilizers. Copper Major sources of copper are from corrosion and leaching of plumbing, fungicides (cuprous chloride), pigments, wood preservatives, larvicides (copper acetoarsenite) and antifouling paints. Major source for lead is from old lead piping in the water distribution system. It can also be found Lead in cosmetics, glazes on ceramic dishes and porcelain (now banned in glazes), crystal glass, solder, pool cue chalk (as carbonate), and in old paint pigments (as oxides, carbonates). Lead can also be found in wines, from lead-tin capsules used on bottles and from old wine processing installations. Most mercury compounds and uses are now banned with the exception of mercury being used in thermometers in some EU countries and dental amalgams. Mercury can still be found as an Mercury additive in old paints and marine antifouling (mercuric arsenate), in old pesticides (mercuric chloride in fungicides, insecticides), in wood preservatives (mercuric chloride), in embalming fluids (mercuric chloride), in germicidal soaps and antibacterial products (mercuric chloride and mercuric cyanide), as mercury-silver tin alloys and for “silver mirrors”. Can be found in rechargeable batteries (Ni-Cd), protective coatings, in alloys used in food Nickel processing and sanitary installations. Selenium comes from food products and food supplements, shampoos and other cosmetics, old Selenium paints and pigments. Originates mainly from small scale photography, household products such as polishes, and Silver domestic water treatment devices. Zinc input are from corrosion and leaching of plumbing, water-proofing products (zinc formate, zinc oxide), anti-pest products (zinc arsenate - in insecticides, zinc dithioamine as fungicide, rat poison, rabbit and deer repellents, zinc fluorosilicate as anti-moth agent), wood preservatives (as Zinc zinc arsenate), deodorants and cosmetics (zinc chloride and zinc oxide), medicines and ointments (zinc chloride and oxide as astringent and antiseptic, zinc formate as antiseptic), paints and pigments (zinc oxide and carbonate), colouring agent in various formulations (zinc oxide), a UV absorbent agent in various formulations (zinc oxide), "health supplements" (as zinc ascorbate or zinc oxide).
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The main domestic sources of potentially toxic elements in wastewater were estimated by WRc (1994) to be (in order of importance):
Cadmium: faeces > bath water > laundry > tap water > kitchen Chromium: laundry > kitchen > faeces > bath water > tap water Copper: faeces > plumbing >tap water > laundry > kitchen Lead: plumbing > bath water > tap water > laundry > faeces > kitchen Nickel: faeces > bath water > laundry > tap water > kitchen Zinc: faeces > plumbing > tap water > laundry > kitchen.
In terms of contributions to domestic wastewater, household washing products contributed 73% of As, 6.5% of Cd, 5.6% of Cr, and 3.2% of Ni (Jenkins and Russel, 1994). In this same study, household washing products contributed for 0.5% or less for Hg, Ag, Pb, Cu and Zn. The source of As was also found to be the phosphate used in some of these products (Jenkins and Russel, 1994).
Table 5.3 Domestic sources of potentially toxic elements in urban wastewater (modified from Lester, 1987 and WRc, 1994 as cited in IC Consultants, 2001) Product type Ag As Cd Co Cr Cu Hg Ni Pb Se Zn Amalgam fillings and thermometers x Cleaning products x x Cosmetics, shampoos x x x x x x x Disinfectants x Fire extinguishers x Fuels x x x x Inks x x Lubricants x x x Medicines and ointments x x x x x Health supplements x x x x x Food products x x x x x Oils and lubricants x x x x Paints and pigments x x x x x x x x x x Photographic (hobby) x x x Polish x x x Pesticides and gardening products x x x x x Washing powders x x x Wood preservatives x x x Other sources Faeces and urine x x x x x x x x x Tap water x x x x x Water treatment and heating systems x x x x x
In a study in Sweden, domestic and some industrial sources of metals to a wastewater treatment plant were investigated and results showed that it was possible to identify the sources for Cu and Zn, as well as for Ni and Hg (70% found). Other metal sources are not well understood or underestimated (Cd 60%, Pb 50%, Cr 20% known; Sörme and Lagerkvist, 2002). In this same study, the major sources of Cu were tap water and roof runoff; the major sources for Zn were galvanised material and car washes; the major sources for Ni were chemicals used in sewage treatment plants and drinking water itself; and finally the
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major source for Hg was the amalgam in teeth. For Pb, Cr, and Cd, where sources were poorly understood, the major source was car washes (Sörme and Lagerkvist, 2002).
Commercial sources of PTEs
Commercial sources of PTEs are summarised in Table 5.4.
Table 5.4 Industrial sources of metals/elements in wastewater (IC Consultants, 2001) Metals/elements Sources Cadmium can originate from laundrettes, small electroplating and coating shops, plastic Cadmium manufacture, and is also used in alloys, solders, pigments, enamels, paints, photography, batteries, glazes, artisanal shops, engraving and car repair shops. Chromium is present in alloys and is discharged from diffuse sources and products such as Chromium preservatives, dying, and tanning activities. Chromium III is used as a tanning agent in leather processing. Chromium IV i s now restricted with few commercial sources. Copper is used in electronics, plating, paper, textile, rubber, fungicides, printing, plastic, and Copper brass and other alloy industries. It can also be emitted from various small commercial activities and warehouses, as well as buildings with commercial heating systems. Lead is used as fuel additive that has now been almost banned in the EU. It is also used in Lead batteries, pigments, solder, roofing, cable covering, lead jointed waste pipes and PVC pipes (as an impurity), ammunition, chimney cases, fishing weights yacht keels and other sources. Mercury is used in the production of electrical equipment and also as a catalyst in chlor-alkali processes for chlorine and caustic soda production. Main sources in effluents are from dental Mercury practices, clinical thermometers, glass mirrors, electrical equipment and traces in disinfectant products (bleach) and caustic soda solutions. Zinc is used in brass and bronze, alloy production, galvanization processes, tyres, batteries, Zinc paints, plastics, rubber, fungicides, paper, textiles, taxidermy and embalming fluid (zinc chloride), building materials and special cements (zinc oxide, zinc fluorosilicate), dentistry (zinc oxide), and also in cosmetics and pharmaceuticals.
5.2.1.2. Upstream control measures
In Section 4, input for Cr, Cu, Pb and Zn following sewage sludge application to soils were more significant than input for other metals. Therefore, sources for these metals in sewage sludge are used to identify potential upstream control measures. With the exception of dredging, input for Cr and Zn to soils from the application of sewage sludge are higher than for any other material. Faeces contribute 60 to 70% of the load of Cd, Zn, Cu and Ni; and are therefore a major source for these metals in sewage sludge. Another source for Cu and Zn is from the corrosion and leaching of pipework, which is also the major source for Pb. For Cr, major domestic sources in sewage sludge have been from household washing products (5.6%) and faeces, whereas major commercial sources are from car washes (20%), the use of chromium as preservative, and from dying and tanning activities. During sewage treatment, the relative distribution of individual PTEs in the treated effluent and in the sludge indicated that Mn and Cu (>70%) mainly accumulate in the sludge, whereas 47-63% of Cd, Cr, Pb, Ni and Zn remain in the treated effluent (Karvelas et al., 2003).
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Potential control measures at the source for these metals are presented below. Reducing metal levels in health supplements. A more rigorous study on the benefits of essential and other minerals in supplements would add clarity in this area. For example, Cr is included in health supplements but there is no biochemical evidence for a physiological function (Stearns, 2000). However, reducing levels of metals in supplements is an impractical approach since these compounds are added because they are trace elements. Also, health supplements are likely to represent only a small proportion of inputs for these metals to sludge.
To reduce inputs of Zn, Cu and Pb to wastewater from the corrosion and leaching of plumbing, other materials could be used. Old pipework, which is responsible for the input of Pb to wastewater, or Cu and Zn use in plumbing (e.g. brass) could be replaced with other materials such as polyvinyl chloride (PVC) or chlorinated polyvinyl chloride (CPVC; e.g. Flowguard or PlatinumXCELL or other plastic. Advantages for using plastic are the much cheaper costs and that it is easier to install, but these are less durable than copper fittings. Replacement of old pipework would take sometime to achieve, however, inputs of these metals to sewage sludge would significantly decrease.
Since car washes are responsible for 20% of Cr inputs into wastewater treatment plants, granular activated carbon (GAC) filters are a water treatment option that may lead to significant reductions in the levels of Cr in sewage sludge.
To educate the public to choose products which are more environmentally friendly. This can be done using ecolabelling in products. A good example is the EU Ecolabel, which is a voluntary scheme first established in 1992, and now reviewed in 2009, that encourage businesses to market products and services that are kinder to the environment (EC, 2009). Products and services awarded the Ecolabel carry the flower logo that allows consumers to identify them easily. Public awareness campaigning would increase the use of these products and services.
More regulation of the industry output, especially for the automotive, construction, and the electronics industry, such as to limit the metal content in finished products and applying legislation to achieve this. However, the practicality of this approach would be low since it would take a long time to achieve.
Research into the development of new substitute materials for metals. Some examples are further discussed within this section for some industries. However, the practicality of this approach would be low since it would take a long time to achieve and there is the need of further research.
5.2.1.3. Treatment
Electro remediation is a method that was developed for the removal of metals from soils. The method is based on the application of a direct-current electric field to soil to remove certain contaminants (e.g. metals). Ottosen et al. (2007) successfully applied this method for the removal of Cd in wastewater sludge.
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5.2.2. Organic compounds
5.2.2.1. Sources
Inputs of persistent organic pollutants to sewage sludge now principally reflect (ADAS, Imperial College, JBA Consulting, 2005): Background inputs to the sewer from normal dietary sources; Background inputs by atmospheric deposition due to remobilisation/volatilisation from soil and cycling in the environment (e.g. PCBs and PAHs); Atmospheric deposition from waste incineration (e.g. PCDD/Fs); Atmospheric deposition from domestic combustion of coal; Biodegradation during sludge treatment; and Volatile solids destruction during sludge treatment.
Many widely used household products that contain hazardous chemicals, including cleaning products, laundry detergents, disinfectants, pesticides, cosmetics, and pharmaceuticals and personal care products, are often present in the effluents treated by sewage treatment plants.
Sources of organic compounds in sewage sludge are presented in Table 5.5.
Table 5.5 Sources of organic contaminants in sewage sludge Organic compound Sources PAHs The major source of PAH emissions are road transport combustion that contributed for 58% of the emissions in 2007 (NAEI, 2009). Domestic and other industrial combustions were the second major sources of emissions in the same year (NAEI, 2009). PCBs Atmospheric deposition onto paved surfaces followed by runoff. Their use has been banned since the late 1970s. PCDD/Fs The most likely source of PCDD/Fs in sludge is atmospheric deposition onto roads followed by transport in runoff to the water system. However, Horstmann and McLachlan (1994) have shown that these contaminants are transferred from textiles to human skin during wearing and therefore were present in shower water and washed out from textiles during washing. LAS LAS are widely used anionic surfactants in detergents and cleaning products (Erhardt and Prüeß, 2001) NPE NPE are extensively used as surfactants in hygienic products, cosmetics, cleaning products, and in emulsifications of paints and pesticides (Erhardt and Prüeß, 2001) Pentachlorophenol The main source of pentachlorophenol is from wastewater collection systems from industrial releases, and also diffuse inputs from surface water runoff. Human Following administration, pharmaceuticals are not completely absorbed and are excreted in pharmaceuticals urine and faeces to sewage treatment, where they are not completely eliminated and are discharged in effluents or in sewage sludge. Improper disposal of drugs might also be a source for these compounds in sludge. Pesticides Especially organochlorines. However, the implications for soil quality mainly arise from direct applications of pesticides to crops and soils and from the application of animal manures rather than from inputs via agricultural application of sewage sludge. Biocides and PCPs They are widely used in domestic products such as clothing, furnishings and hygiene products.
In Table 5.6, common additives used in a range of personal care products are also presented.
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Table 5.6 Description of common additives in a range of personal care products (Xia et al., 2005) Common additive Active compound Description - Musk ketone - Musk xylene Synthetic musks in personal care products are - Galaxolide (HHCB) distributed the following way: - Tonalide (AHTN) - 41% in candles, air fresheners and aroma therapy Fragrances - Phantolide (AHMI) - 25% in perfumes, cosmetics and toiletries - Traseolide (ATII) - 34% in soaps, shampoos, and detergents - Celestolide (ADBI) (Fragranced Products information network, 2004) - Cashmeran (DPMI) Used as additive in flexible polyurethane foam, textile - Tetrabromobisphenol A coatings, and coatings for furniture, in plastics for - Polybrominated diphenylether electrical and electronic equipment, wire, in cable (PBDEs) insulation and electrical connectors, automobiles, and - Polybrominated biphenyl construction and building materials (Bromine Science Flame retardants - Pentabromochloro-cyclohexane and Environmental Forum, 2004). Distribution of the - Hexabromocyclodocdecane 1.14 million tons Mg global consumption of flame - Pentabromotoluene retardants in 1998: - Tetrabromophtalic anhydride -Al-, Mg-, and N-based 56%, Br-based = 23%, P-based = - Tris(2,3-dibromopropyl)phosphate 15%, Cl-based = 6% Bactericide added in detergents, dishwashing detergents, laundry soaps, deodorants, cosmetics, Triclosan (2,4,4_-trichloro-2_- lotions, creams, toothpastes and mouthwashes, hydroxy diphenyl ether) footwear, and plastic wear. It interferes with an enzyme crucial to the growth of bacteria. Bactericide and virucide added in dishwashing detergents, soaps, general surface disinfectants in Disinfectants, hospitals, nursing homes, veterinary hospitals, antiseptics Biphenylol commercial laundries, barbershops, and food processing and pesticides plants. It is used to sterilize hospital and veterinary equipment. Bactericide and fungicide added in disinfectant solutions Chlorophene and soaps. DEET ( N,N -diethyltoluamide) Pesticide added in insect repellant. Butylparaben (alkyl-p- Fungicide added in cosmetics, toiletries, hydroxybenzoates) and food. alkylphenol poliethoxylates Nonionic surfactants added in detergents. (usually branched nonyl or octyl) Sodium Surfactants Ionic surfactants added in detergents. Dodecylbenzenesulfonate Ionic surfactants added in detergents, preservative and Benzalkonium chloride disinfectant in contact lens solutions.
5.2.2.2. Upstream control measures
As for PTEs, the most efficient way to avoid contamination of the sludge with organic compounds would be to reduce their usage at the source.
Atmospheric deposition onto paved surfaces followed by runoff is the major source of PCBs and PCDD/Fs to wastewater. Since emissions controls are already in place (e.g. PCBs have
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been banned) from the main point sources for these organic contaminants and that the main source is from atmospheric deposition, there is little scope to further reduce the inputs of these substances to wastewater or sludge at the source (IC Consultants, 2001). However, during transportation of atmospheric deposits (i.e. runoff), there is a scope to reduce transfer of contaminants into wastewater. To increase To increase water quality from road-runoff some Best Management Practices (BMPs) have been tested by the US Geological Survey (Smith, 2002). One of these BMPs was a deep sumped hooded catch basin to reduce sediment and associated constituents from highway runoff. Results have shown a reduction of around 10% for PAHs.
Potential measures that can be applied at the source to reduce levels of organic contaminants in sludge are presented below.
Pharmaceutical compounds are not completely eliminated during sewage treatment and, therefore, are present in sewage sludge. Upstream control measures to reduce pharmaceutical compounds at the source might be: Drug take back schemes of unused/expired medication are a key mechanism for reducing the discharge of pharmaceuticals to wastewaters. Although the improper disposal of unused/expired pharmaceuticals is believed to be minor, drug take back schemes are still considered important. The practicality and effectiveness for this approach are high since these schemes are already available. These can be more successful with high levels of public awareness and education on the environmental impacts of the disposal of unused/expired drugs (Clark et al., 2008). Risk classification schemes could be used to identify to doctors and general public which pharmaceuticals pose the greatest environmental risk. The aim is that doctors prescribe drugs of low environmental risk. Such a classification scheme was recently developed and introduced in Sweden (Stockholms Läns landsting, 2006). Therefore, a target disposal advice for the less environmentally safe drugs could possibly reduce levels discharged in the environment. However, doctors are most likely to prescribe more efficacious treatments, regardless of the environmental impact. Incentivise might be given to the pharmaceutical companies to make more benign-by-design drugs (e.g. designed to be biodegradable) and the adoption of green chemistry methods and technologies (Clark et al., 2008). These technologies range from novel green catalytic methods, to reduction in solvent use, waste minimization and elimination of hazardous agents (Clark et al., 2008). On a long-term this approach would significantly reduce pharmaceuticals in sludge, however, the practicality of this approach at present is low. Promotion of greener drugs so that providers and consumers can make an informed choice (e.g. hospitals/national and local authorities; Clark et al., 2008). This could be a practical and effective approach. However, greener drugs are still under research and several years are needed for their development. In household toilets, urine source separation might be efficient in reducing amounts of pharmaceuticals in wastewater. Pharmaceutical partition
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between urine and faeces; however, they are expected to be released at higher concentrations in urine. The urine source separation is a new technology that diverts faeces from urine by the use of separate outlet named NoMix-technology. Therefore, by using the NoMix technology, amounts of pharmaceuticals could be greatly reduced in wastewaters. Sweden is the pioneer country using the NoMix-technology that is now being studied in 38 Nomix-projects in seven Northern and Central European countries (Lienert and Larsen, 2010). A global application of this technology is not practical at present. However, locally it could be applied to some institutions (e.g. hospitals and nursing homes). This approach would be very effective in reducing amounts of pharmaceuticals in wastewaters. Alter prescription practices. For example, the prescription of starter packs at the beginning of the treatment and reviewing the patient consumption over time would be likely to reduce amounts of pharmaceuticals prescribed. This approach would be effective on the amount of pharmaceuticals that require disposal.
The new legislation enforced in 2007 and known as REACh (Registration, Evaluation and Authorization of Chemicals) could help reducing levels of organic compounds in sludge (EC, 2006) and controls the manufacture, marketing and use of chemicals around Europe and will require the chemicals industry to provide health and safety information as well as environmental risks on the chemicals produced. This legislation will identify chemicals that can pose an environmental risk and these will need to be substituted by less harmful chemicals since they will not be allowed in the market. On a long term, this will be an effective approach but in practice it will take a number of years to achieve.
Some organic contaminants used in household products can be substituted for less harmful substances (e.g. surfactants in detergents can be substituted by biodegradable substances such as alcohol ethoxilates). Some examples that might be used for reducing levels of organic compounds in sludge are presented below. While the legislation is gradually being enforced, some pressure can be applied to the industry for the substitution of the most harmful substances. Consumer awareness:, Greenpeace published a document titled “Cleaning up our chemical homes- Changing the market to supply toxic-free products” to try to provide information to consumers about the hazardous substances that may be present in products, and to encourage manufacturers to substitute hazardous substances with safer alternatives (Greenpeace, 2007). Products from different companies, including well known brands, were categorised green (no hazardous chemicals used), amber or red according to the hazardous chemicals their products would contain. A chemical database was launched targeting a specific list of hazardous chemicals, including phthalates, synthetic musks, brominated flame retardants, organotins and nonylphenols, and it has been shown that substitution of these substances by safer chemicals is possible in a range of different industries (Greenpeace, 2007).
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The ecolabelling of products to influence the consumer to choose less harmful products can greatly reduce levels of these chemicals in sludge. A successful example occurred in Sweden, where the market shares for ecolabelled detergents increased by 95%. This was only achieved with extensive public awareness campaigning.
5.2.2.3. Treatment
A screening study performed by Bowen et al (2003) showed that some Priority Substances are present at measurable concentrations. Due to the volatile characteristic of these compounds, they are expected to be significantly reduced during standard sewage treatment (ADAS, Imperial College, JBA Consulting, 2005).
Some organic contaminants are removed to the sludge during aerobic wastewater treatment. This is the case for detergent residues (e.g. nonylphenol), surfactants (e.g. LAS), and plasticizing agents (e.g. DEHP). Some organic compounds might be removed by biodegradation during anaerobic digestion, but in general the removal achieved is in the range of 15 to 35%. Aerobic composting and thermophilic digestion processes are usually more effective for degradation of organic contaminants when compared to mesophilic anaerobic digestion (e.g. LAS and NPE; IC Consultants, 2001). In another study, Wetzig (2008) investigated conventional wastewater treatment including coagulation-flocculation and flotation, anaerobic digestion, irrigation and soil passage, a membrane bioreactor, and ozonation for the removal of seven representative pharmaceuticals. None of these treatments was able to eliminate them all, but anaerobic digestion eliminated some.
5.2.3. Pathogens
With the development of the “Safe Sludge Matrix”, sewage sludge needs to be treated before being applied to land. Therefore, during conventional sewage treatment, 99% of pathogens have been removed, and with enhanced treatment sludge is free from Salmonella and 99.9999% of pathogens have been destroyed (ADAS, Imperial College, JBA Consulting, 2005).
5.2.3.1. Upstream control measures
Pathogens do not present a concern for sewage sludge since it undergoes treatment. There are no source control measures to reduce pathogens in sewage sludge.
5.2.3.2. Treatment
Composting, anaerobic digestion, and thermal drying at high temperatures will reduce pathogens in sludge from wastewater treatment plants.
5.2.4. Summary
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Table 5.7 summarises the contaminants that raise more concern in sludge, their major sources and upstream control measures for reducing major contaminants. The strategies that were considered to be the more effective in reducing specific types of contaminants are presented in bold.
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Table 5.7 Upstream control measures for reducing contaminants in sewage sludge Contaminants of concern Major source s Potential upstream control Practicality Effectiveness Justification Car wash water treatment GAC filters could possibly reduce Cr inputs Car washes High High (GAC filter) into wastewater treatment. Chromium Reducing levels in health Health supplements are likely to comprise only Faeces Low Low supplements a small proportion of PTEs loading in faeces. Old pipework Replace metal pipework with The use of plastic pipework would Lead Medium High corrosion plastic pipework significantly reduce amounts of Pb in sludge. It is not possible to control Health supplements are likely to comprise only PTEs Faeces Low Low levels of PTEs in faeces a small proportion of PTEs loading in faeces. Copper Plumbing Replace metal pipework with The use of plastic pipework would Medium High corrosion plastic pipework significantly reduce amounts of Cu in sludge. It is not possible to control Health supplements are likely to comprise only Faeces Low Low levels of PTEs in faeces a small proportion of PTEs loading in faeces. Zinc Plumbing Replace metal pipework with The use of plastic pipework would Medium High corrosion plastic pipework significantly reduce amounts of Zn in sludge. PAHs could possibly be reduced by using a Atmospheric PAHs Catch basin in motorways Medium Medium catch basin to recover sediments and deposition therefore PAHs sorbed onto these. Atmospheric PCBs, PCDD/Fs Measures already in place - - PCBs have been banned. deposition Separation between urine and faeces using the NoMix technology would significantly Urine separation (NoMix reduce levels of pharmaceuticals in sludge. Organic Medium High technology) Although this approach would not be practical compounds for all households it could be locally applied (e.g. hospitals). Pharmaceuticals Urine and faeces Doctors are most likely to prescribe the most Risk classification schemes Medium High efficacious treatment regardless of the environmental impact. This might involve using schemes which Benign-by-design drugs Low High incentivise industry to find these more attractive and several years of research.
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Table 5.7 (cont.) Upstream control measures for reducing contaminants in sewage sludge Contaminants of concern Major sources Potential upstream control Practicality Effectiveness Justification Several more years of research are needed for Urine and faeces Promotion of greener drugs Medium High the development of greener drugs. Take-back schemes are the most practical Take-back schemes for safe High High approach since they are already used as a disposal method to dispose off drugs safely. The prescription of starter packs at the beginning of the treatment and review patient Alter prescription practices Medium High consumption over time might decrease Pharmaceuticals amount of drugs disposed off. Improper disposal Doctors are most likely to prescribe the most Risk classification schemes Medium High efficacious treatment regardless of the environmental impact. This might involve using schemes which Organic Benign-by-design drugs Low High incentivise industry to find these more compounds attractive and several years of research. Several more years of research are needed for Promotion of greener drugs Medium High the development of greener drugs. The use of more biodegradable materials would reduce levels for these organic compounds in sludge. Some are already Detergent Development of substitutes Medium High available and are ecolabelled. The use of LAS, DEHP, NP, residues, and ecolabelling these materials would be likely to flame retardants, plasticizers, significantly increase with extensive public Surfactants. personal care awareness campaigns. products For legislation to be enforced several years REACh Low High are needed and therefore practicality is low for the present.
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5.3. Livestock manure
PTEs, veterinary medicines, biocides, cleaning chemicals and pathogens enter the waste stream via bedding, the animal and cleaning products. The manure and slurry are often stored before land application but can be spread directly. Figure 5.2 illustrates the pathway of contaminants from livestock manures to land.
Figure 5.2 Livestock manure waste stream
Contaminant Organic contaminants
PTEs
POPs Bulk Chemical Pharma- ceuticals Veterina- ry drugs Medicine Pesticide Biocides / PCPs Pathogen
Source
Bedding Animal Cleaning
Production
Manure Slurry
Processing
Stored Compost Anaerobic Co -digestion digestion
Use Land Application
5.3.1. Potentially toxic elements
5.3.1.1. Sources
The metal content of animal manures is a reflection of their concentration in feed and the efficiency of feed conversion by the animal (Nicholson and Chambers, 1997, 2001). Manure might also contain metals ingested through drinking water, that have been added with bedding materials (e.g. straw), from the corrosion of galvanised metal used in the construction of some livestock housing (Zn), or from footbaths used as hoof disinfectants (Zn and Cu; ADAS, Imperial College, JBA Consulting, 2005). The addition of chromium, nickel, lead and arsenic to animal feedstuffs in not allowed under UK or EU regulations (ADAS, Imperial College, JBA Consulting, 2005). The majority of zinc and (53%) and copper (67%) in animal manure inputs come from pigs and poultry production (Chambers et al., 1999).
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5.3.1.2. Upstream control measures
For all livestock, the majority of metals consumed in feed is excreted in the faeces or urine and will therefore be present in manure that is subsequently applied to land. The animals excrete almost all the metals they are fed (Petersen et al., 2007).
In Section 4, input for Cu and Zn following the application of livestock manure, especially pig manure, were more significant than input for other metals. Therefore, sources for these metals in livestock manure are used to identify potential upstream control measures, which are presented below. Sources of Cu and Zn in animal manure are from the addition of these metals to feedstuffs. Therefore, the most important measure to reduce amounts of Cu and Zn in livestock manures is to restrict their incorporation in feedstuffs. This has been recently addressed by a legislation enforced in 2003 (EC, 2003), which reduces the maximum permitted levels of Zn and Cu supplementation in livestock diets. This legislation has been recently applied and therefore practicality is high. However, concentrations for Cu and Zn in livestock manures reported after 2003 are still high. Thus, this approach as yet to be effective in reducing levels for these metals in manure. Further controls are possible through better tailoring the metal levels in feed to the needs of the animal and increasing their bioavailability in the diet. In a meeting in Geneva in 2007, 250 experts discussed how the livestock sector, especially pig farming, is emerging as a significant contributor to environmental concerns (Koeleman, 2007). Experts agreed that the most effective way to reduce the amount of metals in manures is to increase their bioavailability in animal diet. The major conclusion at this meeting was that the current levels of minerals in animal diets within the EU are still too high (Koeleman, 2007). However, to lower the current limits in a sensible way more research is needed on the actual requirements of animals in different life stages, the metal bioavailability, interactions between different minerals, and the use of organic trace element formulations. Nevertheless, some measures have been proposed for the reduction of metals in pig feed: The period when high amount of Zn is added to weaning pig’s diet can be reduced to ten days, which would significantly reduce the amount of metals excreted in manure (Koeleman, 2007). More research is needed to provide evidence for this approach. Several studies have been performed that showed that faecal Zn and Cu concentrations were reduced when a combination of organic and inorganic minerals was fed compared to when only inorganic mineral were fed (sulphate form; as cited in Koeleman, 2007). Also gilts 1 fed reduced concentrations of Cu, Zn, Fe and Mn had lower concentrations in faeces during all phases of production and this did not negatively impact the growth or the reproduction of the gilts or the growth of their offspring (Koeleman, 2007). Research has only been applied to pigs and more research is needed to provide evidence for this approach in other livestock. Mineral supplementation may not be essential since minerals are already present in feed. Premixes may be added irrespective of the contents of the feed (Koeleman, 2007). However, there is no substantive evidence on this. 1 Immature female pigs with fewer than two litters The Food and Environment Research Agency 138
5.3.1.3. Treatment
Storage and composting reduce the volume of manure without reducing the amount of metals and so concentrate them compared to fresh manure (Petersen et al., 2007). In contrast co-digestion or mixing with other wastes dilutes the metals present. Metals in slurry will be found less in the liquid phase and more in the sludge after settlement. Electro remediation could also remove metals from liquid manure (Dach and Starmans, 2006; Petersen et al., 2007).
5.3.2. Organic compounds
5.3.2.1. Sources
Veterinary medicines are extensively used in livestock production to treat diseases and protect animal health. Therefore, veterinary medicines may be present in excreta of farm animals (Boxall et al., 2003, 2004). In the UK, approximately 40 to 45% of the therapeutic use of the 459 tonnes of antimicrobials used are administrated to pigs, suggesting that areas of pig production or where pig slurry is applied on a regular basis will be the most likely to have an impact from the presence of antimicrobials in manures (Burch, 2003).
5.3.2.2. Upstream control measures
Antibiotics are mostly excreted unmetabolised (Sarmah et al., 2006). For example, 65% of cephalosporins (a class of antibiotics) were found to be eliminated in urine (Beconi-Barker et al., 1996). In the animal, the drugs can be metabolised and can be designed to be more effectively metabolised. However, metabolites formed can also be detrimental to the environment. Further information provided by veterinary scientists on medicines may lead to more efficient use by the animal and less excretion.
The most important organic compounds present in manures are veterinary medicines, which include vaccines, antibiotics, antihelmintics (drugs to deal with worms) and Ectoparasiticides (antiparasitic drugs). Potential measures to reduce the amount of veterinary medicines present in livestock manure are presented below.
The current choice of which treatment, within a range of authorised treatments, that is best to prevent or control the condition in the animal relies on the farmer as stated in the Health and Safety Executive (HSE) leaflet. The HSE advises farmers or animal handlers to choose less hazardous chemicals where possible. For example, HSE advise the use of water-based vaccine instead of an oil-based one. An option for the application of this measure would be to educate farmers and veterinarians on which products to use to reduce environmental impact. The practicality of this approach is high since this option is already available for some substances, however, it is unlikely that this measure would greatly reduce amounts for veterinary medicines in manures because for most veterinary medicines these are not available.
Veterinary medicines are typically used in livestock in a prophylactic manner to prevent diseases. Restricting veterinary medicine use to only treat animals that are showing signs of illness would greatly reduce the amount of these organic The Food and Environment Research Agency 139
compounds from manures. This could be done by separating sick animals to try to avoid the spread of disease to healthy animals. This approach would be likely to significantly reduce amounts of veterinary medicines in manures.
Improved animal husbandry practices such as a shift to less intensive rearing and increased attention to hygiene. This can resolve many of the situations where the disease and stress load on animals might warrant the use of veterinary medicines (WHO, 1997; Witte, 1998). The practicality for this approach is low since less intensive rearing will not be easily achieved with the increase of animal production in recent years and there is no evidence that this would reduce disease in animals.
Development of benign-by-design veterinary medicines that would be more biodegradable than the ones that are currently used. However, the practicality for this approach is low since several years of research would be needed.
5.3.2.3. Treatment
The effectiveness of any treatment depends on the particular drug in the manure. Some medicines and their metabolites are persistent and are not completely removed through anaerobic digestion and composting (e.g. oxytetracycline and metabolites; Arikan et al., 2006, 2007). Some may inhibit the anaerobic digestion process (e.g. chlortetracycline; Sanz et al., 1996). It is beyond the scope of this study to look at these drugs in detail but as more data is gathered and ERA performed, there will be more knowledge of the best treatment methods.
5.3.3. Pathogens
5.3.3.1. Sources
Animal manures contain pathogenic elements in variable quantities depending on the animal health. Pathogenic microorganisms such as Esherichia c. O157 , Salmonella, Listeria, Campylobacter, Cryptosporidium and Giardia have all been isolated from cattle, pig and sheep manures (ADAS, Imperial College, JBA Consulting, 2005).
5.3.3.2. Upstream control measures
Veterinary medicines are administered to reduce certain harmful pathogens and diseases. Waste from infected animals with high risk diseases such as BSE should be disposed of separately and not spread on land. However, most pathogens of concern to human health do not affect animals and so are not treated with medicines.
Upstream measures to reduce pathogens in manures are presented below.
Keep animals healthy and comfortable. Sick or stressed animals are more likely to shed pathogens in their manure. Simple management practices such as vaccinations, adequate access to feed and water, appropriate space allowance, right temperature and ventilation, on-farm sanitation and good animal husbandry practices can reduce
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pathogens in manures (Spiehs and Goyal, 2007). This is a practical approach that might significantly reduce pathogens in manures.
The type of animal housing facility can also reduce the levels for some pathogens. For example, Salmonella levels decreased when slotted floors are used when compared to other types of floors such as concrete for swine (Davies et al., 1997). This might be due to the fact that animals housed on solid floors are often exposed to contaminated faeces, whereas the contaminated faeces from animals in a slotted floor barn fall to the underground pit (Spiehs and Goyal, 2007). Although this approach is possible and could reduce levels for some pathogens, it is unlikely they would be significantly reduced.
Pathogens in manure can be reduced by diet selection (Spiehs and Goyal, 2007). One way to achieve this is by adding antimicrobials to livestock diets. However, if antimicrobials are used to control pathogens in manures, producers should only use this approach only to treat specific diseases (Spiehs and Goyal, 2007). This approach might reduce pathogens in manures; however, it would also increase amounts of veterinary medicines.
5.3.3.3. Treatment
Literature suggests that temperature is the most important factor determining pathogen survival in manures (Nicholson et al., 2007). In general, pathogens are destroyed after a short time at high temperatures (> 55°C) and by freezing. Nevertheless, even at lower to moderate temperatures a decline of pathogens numbers occurs over time, especially under dry conditions or exposure to UV radiation. The rate of pathogen decline in manures is dependent on the storage and weather conditions. Temperature, aeration, pH and manure composition have been shown to influence the rates of pathogens decline during storage. With increased storage duration, pathogen levels gradually decline (ADAS, Imperial College, JBA Consulting, 2005). Due to the lower temperatures in winter than in summer, pathogen survival times are increased. Solid manure storage for one month is likely to be sufficient to ensure elimination of most pathogens, provided that elevated temperatures (> 55°C) have been reached within the pile. However, a small risk might still exist since pathogens may survive in the cooler exterior or dryer part of the heap. Therefore, the turning and composting of manures to thoroughly mix and promote higher temperatures should ensure effective pathogen kill.
Anaerobic and aerobic treatment of slurry can reduce the levels of slurry pathogens. However, this is an expensive approach and would only be partially effective on the reduction of pathogen levels. A more appropriate way would be to increase slurry storage capacities, which would not only reduce pathogen levels but would also have the potential for improved nutrient management practices (ADAS, Imperial College, JBA Consulting, 2005).
Many farmers spread manures directly onto soils because they do not have storage facilities or for convenience and thus this practice presents a higher risk of pathogen transfer to soils since there is no storage time for the decline of pathogen levels (ADAS, Imperial College, JBA Consulting, 2005). The Food and Environment Research Agency 141
5.3.4. Summary
Table 5.8 summarises the contaminants that raise more concern in livestock manure, their major sources and upstream control measures for reducing major contaminants. The strategies judged to be more effective are shown in bold.
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Table 5.8 Upstream control measures for reducing contaminants in livestock manure Contaminants of concern Major source s Potential upst ream control Practicality Effectiveness Justification Legislation has been applied and levels Reduce levels in feedstuffs High Medium remain too high. Copper With increased bioavailability of copper and zinc in animal diet, then it is likely that lower amounts are Increase bioavailability in animal diet Medium High PTEs Feedstuffs needed in feedstuffs, which would therefore effectively reduce levels in manure. Zinc Use of combination between organic Research is only available for pigs and Low Medium and inorganic minerals formulations more evidence is needed Reduce period of animal intake Low High More evidence needed Educate farmers to choose less Would not greatly reduce amounts in High Low hazardous chemicals manure Restricting veterinary medicine use to Restrict veterinary medicines to sick sick animals would greatly reduce the High High animals amount of these organic compounds Organic Veterinary Prevention and from manures. compounds medicines treatment of animals Improvement of animal husbandry Less intensive rearing is not a practical Low Medium practices (e.g. less intensive rearing) approach. This might involve using schemes which incentivise industry to find these more Benign-by-design drugs Low High attractive but several years of research required. Sick or stressed animals are more Keeping animals healthy and Medium High likely to shed pathogens in their comfortable manure. Pathogens NA Faeces Use of slotted floors for animal housing Low Medium Pathogens not greatly reduced Change of diet by addition of Would increase amounts of organic High High antimicrobials compounds instead NA – not available
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5.4. Municipal solid waste
Municipal solid waste (MSW) contains domestic waste, kerbside collected waste, source separated waste, and non-municipal waste. The waste can be source segregated or mechanically separated. From the wide range of origins there are a wide range of contaminants. Figure 5.3 shows the path of contaminants from MSW to land.
Figure 5.3 Municipal solid waste stream
Contaminant Organic contaminants
POPs POPs Bulk Chemical Pharma- ceuticals Veterina- ry drugs Pesticide s /Biocides personal care products Pathogen PTEs PTEs
Source
Municipal waste Non-municipal waste
Production
Mechanical Source separation separation
Processing
Compost Anaerobic digestion
Use
Land Application
5.4.1. Potentially toxic elements
5.4.1.1. Sources
There is variability in levels of PTEs in this waste stream due to location, seasonality and collection method (Amlinger et al., 2004b).
Metal contaminants can be introduced into MSW by batteries, consumer electronics, ceramics, light bulbs, house dust and paint chips, lead foils (e.g. wine bottle closures), used motor oils, plastics, and some glass and inks can (Richard and Woodbury, 1998). Batteries are a significant source of metals in MSW. Even after 80% of lead-acid automobile batteries are recovered for recycling, the remaining 20% are estimated to contribute 66% of
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the lead MSW in the USA (Richard and Woodbury, 1998). Ni-Cd household batteries may be responsible for up to 52% of the Cd (Richard and Woodbury, 1998). Source-segregated feedstock materials, standardised to an organic matter content of 30% dry matter, frequently exceed the averaged limit-values for biowaste compost in the EU (Amlinger et al., 2004b): Paper (Cu, Zn) Potatoes (Cd, Cu, Zn) Tomatoes (Cd) Spinach (Cd) Mushroom (Cd, Cu, Hg, Zn) Garden waste (Cd) Kitchen waste (Cd, Ni) Wood chippings (Pb, Zn)
5.4.1.2. Upstream control measures
Some upstream control measures can be used for all contaminants, including PTEs and these are presented below.
Segregation of municipal solid waste is one of the best approaches for reducing contaminants, including PTEs, and cross contamination between different waste types in feedstock materials for composting or anaerobic digestion. Mechanical and biological treatment (MBT) facilities include magnetic and electrical separation techniques to remove metal waste (Defra, 2007d). However, source separation is more effective than mechanical sorting (Braber, 1995). This approach would not only increase the amount of waste that is recycled but also the quality of the final output materials. Educating people on reducing household waste and increasing recycle and/or reuse of materials would be extremely effective in reducing contaminants.
Stewardship schemes might be used to increase recycling, reduce waste and therefore all contaminants and these might include: “pay by weight” contract – this scheme has been used at some UK universities and involves the weighing of each collected container. The outcome was a reduction of the average number of empty bins collected per week and consequent financial savings. This approach could be used for commercial organisations and industry. The beverage container refund program has been very successful in Canada, with a 95% return rate. In this scheme, a small amount of money is charged upfront when the beverage is bought and is refunded when the recipient is returned. This could be applied to cans, bottles and plastic containers.
In Section 4, input for Cd, Cr and Pb following the application of composted materials to soils, were more significant than input for other PTEs or any digestates. Pb input from composted materials is significantly greater than for any other material that is applied to land. Therefore, sources of these metals in compost and digestate are used to identify
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potential upstream control measures specifically for these metals, which are presented below.
Recycling would significantly decrease amounts of PTEs in waste feedstocks. For example, recycling batteries would significantly decrease amounts of Cd and Pb, recycling paper would decrease amounts of Cr, and separation of kitchen waste would decrease further amounts of Cd. This would be the more efficient approach to use and would also reduce waste volume.
Use of rechargeable batteries is a practical and effective approach to reduce contamination.
Using Cd -free batteries. This approach is practical and is likely to greatly reduce amounts of Cd in MSW.
5.4.1.3. Treatment
The organic fraction from MSW is composted or anaerobically digested which may increase the heavy metal concentration due to the decreasing volume.
5.4.2. Organic Compounds
5.4.2.1. Sources
Organic compounds, such as pharmaceuticals, fragrances, surfactants, and ingredients in household cleaning products, are likely to be found in waste streams (Eriksson et al . 2008).
Degradation-resistant herbicides, even at very low concentrations, have been identified as a source of plant phytotoxicity of composts derived from garden waste (Hogg et al., 2002).
5.4.2.2. Upstream control measures
Strategies to reduce the amount of organic compounds at the source in municipal solid waste are similar to those applied for the reduction of organic compounds in sewage sludge (section 5.2). Upstream control measures previously presented for PTEs might also be used to reduce organic compounds from municipal solid waste.
5.4.2.3. Treatment
Mechanical sorting is not effective at removing most organic contaminants, but the biological treatments will digest some. For example, composting and anaerobic digestion remove some organic compounds (e.g. LAS and low molecular weight phthalate esters, respectively; Amlinger et al., 2004b).
5.4.3. Pathogens
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Separation of waste streams may separate types of pathogen to some extent but pathogens multiply and cross contamination is likely.
5.4.3.1. Treatment
Composting and anaerobic digestion can significantly reduce pathogens. Only source segregated waste can be composted or anaerobically digested to meet the PAS 100 and PAS 110 standards, respectively (BSI, 2005).
5.4.4. Summary
Table 5.9 summarises the reduction techniques. The strategies that are considered more effective are presented in bold.
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Table 5.9 Upstream control measures for reducing contaminants in municipal solid waste Contaminants of concern Major source s Potential upstream control Practicality Effectiveness Justification Source segregation of waste/ Involves extensive public awareness but recycling Medium High effective measure. (e.g. stewardship incentive sche mes) Batteries Use of rechargeable batteries High Medium Less often disposed but still disposed. Cadmium The use of Cd-free batteries is likely to Use of Cd-free batteries High High greatly reduce cd in MSW and these are already available. Only represents a small proportion of Cd in Kitchen waste Source segregation of waste Medium High PTEs MSW. Source segregation of waste/ Involves extensive public awareness but recycling Medium High effective measure. (e.g. stewardship incentive schemes) Chromium Paper Cr in paper is mainly from inks. Thus, the Use of metal free inks High High usage of metal-free inks would greatly reduce levels for Cr in MSW. Recycling Lead mainly comes from car batteries for Lead Batteries (e.g. stewardship incentive High High which there are already available schemes schemes) for recycling. Take-back schemes are the most practical Take-back schemes for safe disposal High High approach since they are already used as a method to dispose off drugs safely. The prescription of starter packs at the beginning of the treatment and review Alter prescription practices Medium High patient consumption over time might Pharmaceuticals, Organic decrease amount of drugs disposed off. veterinary Improper disposal compounds Doctors are most likely to prescribe the medicines Risk classification schemes Medium High most efficacious treatment regardless of the environmental impact. This might involve using schemes which Benign-by-design drugs incentivise industry to find these more Low High attractive but several years of research required.
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Table 5.9 (cont.) Upstream control measures for reducing contaminants in municipal solid waste Contaminants of concern Major sources Potential upstream control Practicality Effectiveness Justification Pharmaceuticals, Several more years of research are needed veterinary Improper disposal Promotion of greener drugs Medium High for the development of greener drugs. medicines Biopesticides are biodegradable pest management tools based on beneficial Use of biopesticides High High organisms and made with biologically based active ingredients. Pesticides Improper disposal Organic Use/disposal guidance Medium Medium Not as effective as chosen option. compounds For legislation to be enforced several years REACh Low High are needed and therefore practicality is low for the present. Detergent Use/disposal guidance Medium Medium Not as effective as chosen option. LAS, DEHP, NP and residues, other organic For legislation to be enforced several years surfactants, compounds REACh Low High are needed and therefore practicality is low plasticizers for the present.
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5.5. Paper and pulp waste
Paper mills process virgin wood and recycled paper into pulp and then paper. Figure 5.4 illustrates this waste production stream. Some UK mills are authorized under Integrated Pollution Control demonstrating the use of Best Available Techniques Not Entailing Excessive Cost (BATNEEC; Thompson et al., 2001).
Figure 5.4 Paper mills waste stream
Contaminant Organic contaminants
-
POPs POPs Bulk Chemical Pharma- ceuticals Veterina ry drugs Pesticide s Biocides / personal care Pathogen PTEs PTEs
Source Recycled Virgin wood Deinking and bleaching chemicals
Production Deinking sludge Primary sludge
Activated Combined sludge sludge
Processing
Compost Anaerobic Co -digestion Incineration digestion
Use Land Application
5.5.1. PTEs
5.5.1.1. Sources
Sources of metals in paper and pulp waste are from the printing inks in the form of metal- based pigments, driers or as contaminants in the raw materials used in the formulation process (Napim, 2010). These include metallic printing inks, generally based upon systems containing Cu and brass (alloy of Cu and Zn), and inks that use metal-based driers, which include driers based on Zn and Ca. Impurities and contaminants in inks might include PTEs such as Cd, Cr and Pb (Napim, 2010). From recycled paper, metals are introduced primarily through inks, in the deinking sludge. Copper is the most significant metal in deinking paper sludge (Beauchamp et al., 2002; Rashid et al., 2006). As more paper is being recycled the levels of copper in paper wastes
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have increased (Tandy et al., 2008). To reduce the inputs, inks without metal content should be used on papers destined to be recycled.
PTE may also be introduced through wood if the trees have been treated with CCA (copper, chromium and arsenic) or if trees have been grown on contaminated soil, but this is not considered as a major route.
5.5.1.2. Upstream control measures
The processes used in paper and pulp industries are designed to remove the trace metals from effluent so that it can be reused or disposed off, which leaves the trace metals in the sludge.
According to section 4, the PTEs of higher concern in paper waste are Cd, Cr, Pb and Zn. Upstream control measures for the paper and pulp industry are presented below.
Use of metal-free inks – this would be the most effective strategy to reduce metal contamination in sludge. Metal-free inks are vegetable oil-based (Telschow, 1994) and can prevent pollution in: the waste ink produced by a printer, that is currently disposed of as hazardous waste; the printed materials that are landfilled or incinerated; and the sludge that is created during the deinkning and repulping of waste paper fibres as they are made into recycled paper (Telschow, 1994).
Separate de-inking sludge from other waste - keeping de-inking sludge separated from other sludges that do not contain such high levels of PTEs would also be likely to reduce contamination. This approach is practicable and effective, however, not as effective as eliminating the use of metals in the first instance.
Use of untreated wood as raw material – making sure that the wood used in paper industry does not contain PTEs reduces contamination of paper waste by these contaminants. This would require analysis of the raw materials in the paper and pulp industry, but would not be very effective since a much larger proportion of metals are from the use of inks.
5.5.1.3. Treatment
The METIX-AC is a process to remove metals from sludge. It involves the chemical leaching of metals from sludge with the use of sulphuric acid and strong oxidants (e.g. hydrogen peroxide). This process has been shown to remove copper, cadmium, and zinc from sludge, while preserving satisfactory levels of nutrients (Barraoui et al., 2008). However, Barraoui et al. (2008) concluded that this method was inefficient for the removal of Cr and Pb from all tested sludges and is probably not adapted for the removal of Cu from the pulp and paper industry sludge.
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5.5.2. Organic Contaminants
5.5.2.1. Sources
Many chemicals are added in the production process, chlorine for bleaching (measured as AOX), surfactants in the flotation process (Tandy et al., 2008), biocides to stop microbial growth (PITA, 2009), and dyes to colour the paper. Naturally occurring fatty and resin acids are present (Beauchamp et al., 2002; Rashid et al., 2006). Organic contaminants may also be present in recycled paper ink and coatings. Appendix F shows a list of potential contaminants (DoE, 1996b).
5.5.2.2. Upstream control measures
The most important organic contaminants in the paper and pulp industry are the chlorine products used during the bleaching process, measured as AOX. Upstream control measures for reducing concentrations of organic compounds in the paper and pulp industry are presented below.
Use of non-chlorinated products in the bleaching process - public concern about the environmental hazard of using chlorine in the bleaching process has resulted in a dramatic decrease over the last decade (IPPC, 2001). Therefore, there was also an increase on the use of Totally Chlorine Free (TCF) and Elementary Chlorine Free (ECF) bleaching processes, which reduced the chlorinated organic substances in the waste. This is the most effective and practical approach to reduce organic compounds contamination in waste.
Environmental risk assessment on the chemicals added to the paper making processes would allow educated choices on chemicals to use and encourage research on alternatives. The use of legislation, such as REACh, could enforce this measure. Practicality for this approach is judged low since several years are still needed for legislation to be enforced.
Separate collection and intermediate storage of waste fractions at the source would minimise the solid waste and increase the recovery, recycling and re-use of these materials when possible (IPPC, 2001). This approach would be effective, however, not as effective as eliminating the use of contaminants in the first instance.
5.5.2.3. Treatment
During activated sludge treatment, which breaks down organic contaminants (AOX and chlorinated phenols), filamentous algae may build up and cause further operational problems. Chemicals can be added to prevent this but a better alternative is to use an ultrafiltration membrane to exclude the microorganisms or pre-treatment ozonation (Thompson et al., 2001).
Anaerobic digestion and composting are the most common treatments for paper and pulp sludge. Resin, fatty acids and PAHs are mostly undetectable after 24 weeks of composting
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(Beauchamp et al., 2002). In a comparative study of different treatments Pokhrel and Viraraghavan (2004) concluded that anaerobic followed by aerobic treatment was the best combination. Although, the long residency time of anaerobic digestion has been a deterring factor in its use, new improvements in technology including thermophilic digesters may encourage use (Elliott and Mahmood, 2007).
Deinking paper sludge has been successfully treated using supercritical water oxidation by a Swedish company “Chematur”. However it has not become a common treatment due to expense and transport, and reactors need to be designed to deal with specific wastes (Kritzer and Dinjus, 2001). Fungal treatments for colour removal are also proved to be effective (Pokhrel and Viraraghavan, 2004).
5.5.3. Pathogens
5.5.3.1. Sources
Thermo tolerant coliform bacteria enter the paper process through wood chips (Beauchamp et al., 2006).
5.5.3.2. Upstream control measures
Despite the chemicals used in the processes pathogens have been reported to survive in paper mill effluents, to increase density in the primary clarifier and to multiply in the combined sludges (Beauchamp et al., 2006). Keeping sludges with coliforms separated will reduce cross contamination. Nevertheless, pathogens are not expected to be of concern in paper and pulp waste.
5.5.3.3. Treatment
Deinking sludge and biological treatment sludge are both successfully composted, separately and together, without other amendments and can reach thermophilic conditions required for sanitation (Gea et al., 2005).
5.5.4. Summary
Table 5.10 summarises the reduction techniques. The strategies judged the more effective for each contaminant are shown in bold.
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Table 5.10 Upstream control measures for reducing contaminants in paper and pulp waste Contaminants of concern Major source s Potential upstream control Practicality Effectiveness Justification Using metal-free inks would eliminate PTEs in the ink produced by a printer; in the Use of metal-free inks High High printed materials that are landfilled or Cadmium Ink incinerated; in the sludge created during de-inking in paper recycling. Separate de-inking sludge from other paper Not as effective as eliminating the use of Medium High waste PTEs in inks. Using metal-free inks would eliminate amount of PTEs in the waste ink produced Use of metal-free inks High High by a printer; in the printed materials that Lead Ink are landfilled or incinerated; in the sludge created during de-inking in paper recycling. Separate de-inking sludge from other paper Not as effective as eliminating the use of Medium High waste PTEs in inks. Using metal-free inks would eliminate PTEs in the waste ink produced by a printer; in PTEs Use of metal-free inks High High the printed materials that are landfilled or incinerated; in the sludge created during Ink Chromium de-inking in paper recycling. Treated wood Separate de-inking sludge from other paper Not as effective as eliminating the use of Medium High waste PTEs in inks. Use of untreated wood as raw material in Medium Low Not a significant reduction of Cr. paper industry Using metal-free inks would reduce amount of PTEs in the waste ink produced Use of metal-free inks High High by a printer; in the printed materials that are landfilled or incinerated; in the sludge Ink Copper created during de-inking in paper recycling. Treated wood Separate de-inking sludge from other paper Not as effective as eliminating the use of Medium High waste PTEs in inks. Use of untreated wood as raw material in Medium Low Not a significant reduction for Cu. paper industry
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Table 5.10 (cont.) Upstream control measures for reducing contaminants in paper and pulp waste Contaminants of concern Major sources Potential upstream control Practicality Effectiveness Justification Using Totally Chlorine Free (TCF) and Elementary Chlorine Free (ECF) bleaching Use of non-chlorinated compounds High High processes reduces concentrations of chlorinated organic substances in waste. Organic Chlorine products AOX used in the bleaching Not as effective as eliminating the use of Compounds Separate collection of waste fractions Medium High process AOX in inks. For legislation to be applied several years REACh Low High are needed and therefore practicality is low at present.
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5.6. Waste wood, bark and other plant waste
Figure 5.5 illustrates the path of contaminants in wood and plant waste. Wood waste is being increasingly reused where possible, and what is not reused, can be recovered for land spreading. Wood that is reused for other products such as cardboard or fibreboard will eventually become waste again with the potential for soil application.
Much of the plant material waste from parks and gardens are treated by mechanical biological treatment facilities or composted.
Figure 5.5 Waste wood, bark and other plant waste
Contaminant Organic contaminants
-
POPs POPs Bulk Chemical Pharma- ceuticals Veterina ry drugs Pesticide s / Biocides personal care products Pathogen PTEs PTEs
Source
Untreated Reclaimed/ Plant material wood treated wood
Production
Wood and plant Waste
Processing
Compost Anaerobic digestion
Use
Land Application
Risk assessment has shown that more research is needed before treated wood can be composted for soil application (Table 5.11; WRAP, 2005). Copper, chromium and arsenic (CCA) and creosote treated wood is regulated under the Environmental Protection (Control of Dangerous Substances) Regulations (SI 2003/3274) and The Creosote (Prohibition on Use and Marketing) Regulations (SI 2003/791) respectively and cannot be used for soil application.
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Table 5.11 Result of risk assessment of treated waste wood (WRAP, 2005)
5.6.1. PTEs
5.6.1.1. Sources
Accurate data on wood waste is not readily available, but a study of waste wood from Civic Amenity sites found that 85% of the wood was treated with some product (WRAP, 2005). Treated waste wood includes wood treated with CCA, copper organics, creosote, light organic solvent preservatives (LOSP), paint and stain, and varnish. However, PTEs content of wood wastes are likely to be low. PTEs are unlikely in plant waste and untreated wood unless they have been grown on contaminated ground.
Most treated wood is not suitable for use as compost and should not be used. However, waste wood may be used for other products that eventually find their way back into the waste stream e.g. via chipboard or packaging. For this reason, a record from where wood has been sourced would be useful to identify potential contaminants without testing.
5.6.1.2. Upstream control measures
No data has been found on the input of PTEs from waste wood, waste bark and other plant waste to soil following landspreading. However, inputs of PTEs are likely to be low.
The most efficient approaches to reduce PTEs contamination in wood, where treatments using PTEs are used, are presented below.
Restrict the use of PTEs during wood treatment- wood is treated with CCA and copper organics. Restricting the use of these PTEs based preservatives reduces the amount of the PTEs in wood. This approach might not be practicable, since no data on other methods to treat wood have been found.
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Separate woods according to the treatment to which they were subjected. For example, SMARTWaste (www.smartwaste.co.uk) is a waste auditing tool in operation in the UK where the waste wood is separated into 12 groups, one of which is timber. This increases the amount of wood that can be composted, re-used and recycled. This approach has been used and therefore practicality is judged as high. It would also be effective since different treatments might be applied for the removal of different contaminants.
5.6.1.3. Treatment
Although treated wood cannot be used, some emerging technologies have produced good recovery rates of wood and metals. A dual remediation process using oxalic acid and Bacillus licheniformis CC01 removed 78% copper, 97% chromium, and 93% arsenic from waste wood (Claussen, 2000). In another study, 93% of copper, 95% of chromium, and 99% of arsenic were removed by electrodialytic removal (Ribeiro et al., 2000).
5.6.2. Organic Compounds
5.6.2.1. Sources
Creosote, light organic solvent preservatives (LOSP), micro-emulsion, paint and stain, and varnish may be present in wood waste. Regarding plant waste, pesticides are used on plants and are therefore likely to enter the plant waste stream. More research is needed before composting wood treated with organic chemical preservatives, paint, and varnish (WRAP, 2005).
5.6.2.2. Upstream control measures
Upstream control measures to reduce concentrations of organic compounds in wood waste, bark waste and other plant material are presented below.
Source separation of woods according to the treatment to which they were subjected (e.g. SMARTWaste). Again, this approach seems to be effective in separating different contaminants that might be removed with further treatment.
Environmental risk assessment of chemicals used – this measure applies to wood and plant waste. For example, environmental risk assessment of preservatives and pesticides applied to wood and plant, respectively, would allow educated choices on which chemicals to use and encourage research on alternatives. The use of legislation, such as REACh, could enforce this measure. Practicality for this approach is judged low since several years are still needed for legislation to be enforced.
Alternatives for pesticides – biopesticides are an alternative to persistent compounds. These are biodegradable pest management tools based on beneficial microorganisms, nematodes or other safe, biologically based active ingredients. This approach is the more effective way to reduce pesticide residues in plant waste. But biopesticides are not available for all plant protection product requirements.
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Usage/ disposal guidance for the use of pesticides by the public– presently, guidance on how to use pesticides and on how to dispose them after usage is not very clear. This approach would be effective to reduce pesticide contamination; however, eliminating the use of these chemicals in the first instance is more effective.
Composting of the waste will break down some organic contaminants but more field research is needed to get accurate data.
5.6.3. Pathogens
Pathogens are not deliberately introduced but can always be present.
5.6.3.1. Sources
With green plant material and rotted roots there is a possibility of plant pathogens, particularly fungi being present (Davis and Rudd, 1999). A list of potential toxins found in green compost and that could also be found in plant waste is presented in Appendix D. Therefore, the origin of waste plant matter has to be considered in case diseased material is present that could act a source of infection for crops.
5.6.3.2. Treatment
Anaerobic digestion or composting the waste will reduce pathogens to an acceptable level. Treating plants and wood to remove pathogens will add other contaminants to the waste stream.
5.6.4. Summary
Table 5.12 summarises the upstream control measures that can be applied to reduce contaminants for wood, bark and other plant waste streams. The strategies judged to be more effective for each contaminant are shown in bold.
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Table 5.12 Upstream control measures for reducing contaminants in wood, bark and other plant waste Contaminants of concern Major source s Potential upstream control Practicality Effectiveness Justification Separation of woods according to Arsenic treatment received e.g. Separate woods according to treatment High High SMARTWaste. This would increase received. the re-use, recycle and composting of PTEs Chromium Wood treatment wood waste.
Restrict the use of PTEs based No other treatments seem to be Copper Low High preservatives. available. Separation of woods according to treatment received e.g. Separate woods according to treatment Creosote, High High SMARTWaste. This would increase received. preservatives, micro- the re-use, recycle and composting of Wood treatment emulsion, paint and wood waste. stain, and varnish For legislation to be enforced several REACh Low High years are needed and therefore practicality is low at present. Organic Biopesticides are biodegradable pest Compounds management tools based on Use of biopesticides High High beneficial organisms and made with biologically based active ingredients. Not as effective as eliminating the use Pesticides Plant treatment Use/disposal guidance Medium Medium of these chemicals in the first instance. For legislation to be enforced several REACh Low High years are needed and therefore practicality is low at present. Plant This will avoid contamination of Pathogens Fungi Carefully select raw material High High Wood wastes with fungi or plant pathogens
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5.7. Dredgings from inland waters
Figure 5.6 shows that contaminants enter the water and either settle into or are adsorbed onto the sediment.
Figure 5.6 Dredgings waste stream Contaminant Organic contaminants
-
POPs POPs Bulk Chemical Pharma- ceuticals Veterina ry drugs Pesticide s / Biocides personal care products Pathogen Heavy Metals
Source
Sewage works Industrial Agricultural land Diffuse sources output discharge
Water and Sediment
Production
Drained on adjacent land
Processing
Compost Anaerobic digestion
Use
Land Application
Contaminants can enter from both diffuse and point sources and the types and quantities vary widely due to location of the waterway. Whether it is a rural or industrial area, fast or slow flowing waterway, and frequently or rarely dredged waterway, will affect the contaminant content of the dredging. Sediments may have built up for years and may have been taken from places where there are industrial areas. Therefore, contaminants related to those industries may be detected in those sediments (Gendebien et al., 2001). By dewatering the sediment alongside the waterway, rain and leachate may wash metals in solution back to the waterway and re-contaminate the sediment and surrounding soil.
According to section 4, input of PTEs following the application of dredging to soil is much higher than inputs from any other materials. However, areas from where those concentrations are reported are not specified and might be from urban and extremely polluted areas. Therefore, before application, levels of contaminants should be checked and if levels of contaminants are high those sediments should not be applied to land.
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5.7.1. PTEs
5.7.1.1. Sources
The main source of PTEs into the water is from sewage works and industrial discharges. PTEs might also enter waterways through the runoff from fields where sewage sludge or livestock manures have been applied. The Water Framework Directive (WFD) works to reduce inputs into waterways but PTEs may still be present from past releases. Therefore, sources of PTEs in dredging materials are the same as the ones discussed for sewage sludge (section 5.2.) and livestock manure (section 5.3.).
5.7.1.2. Upstream control measures
According to section 4, concentrations of PTEs in sediments are so high that they were not comparable to any other waste. Upstream control measures to reduce concentrations of PTEs in dredging are presented below.
Upstream control measures for reducing PTEs in dredgways are the same as those discussed for sewage sludge (section 5.2.) and livestock manure (section 5.3.) and these would likely to reduce amounts of PTEs discharged by municipal and industrial STPs and/or runoff from fields. Livestock manure upstream control measures have been considered less effective than sewage sludge approaches since PTEs in runoff are likely to represent a small proportion of PTEs applied to fields. Measures for sewage sludge would reduce amounts of organic compounds in effluents directly discharged from sewage treatment plants into surface waters, and could therefore reduce levels in dredgings. However, since PTEs do not degrade, they will still be present due to existing contamination.
5.7.1.3. Treatment
The digestion of the dredging will not reduce the metal content, but leaching may. Use of sensors to provide data on the sediments may guide potential choices of treatment needed before spreading the dredgings Alcock et al. (2003). Records of previous tests and contaminant levels in areas will provide a history for dredged waterways. Therefore contamination may be able to be predicted and suitable treatments selected if appropriate or cost effective.
5.7.2. Organic Contaminants
5.7.2.1. Sources
Organic contaminants can enter from diffuse sources such as runoff from agricultural land and point sources in industry or sewage works. Therefore, sources of organic contaminants in dredging are likely to be the same as sources of organic contaminants in sewage sludge (section 5.2.) and livestock manure (section 5.3.).
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Decreasing the use and production of persistent organic contaminants in general will reduce what enters waterways. The WFD is designed to reduce such inputs into waterways. Persistent contaminants will be still present even if their use has been banned (e.g. DDT).
5.7.2.2. Upstream control measures
Upstream control measures to reduce organic compound contamination in sediments are presented below.
Suggested measures to control organic compound contamination in sewage sludge (section 5.2.) and manure (section 5.3.) will also be relevant for dredgings. Measures for sewage sludge would reduce amounts of organic compounds in effluents directly discharged from sewage treatment plants into surface waters and could therefore reduce levels in dredgings.
5.7.2.3. Treatment
At the sediment floor of waterway the processes are predominantly anaerobic. By bringing the sediment out of the water into the air the aerobic processes take place. This will allow degradation of some contaminants. Composting will continue and increase degradation of organic contaminants but some may persist.
5.7.3. Pathogens
5.7.3.1. Sources
Pathogen sources in waterways are likely to be the same as sources for PTEs and organic compounds. When the sediments are out of the water and in the right conditions pathogens might continue to multiply.
5.7.3.2. Treatment
Composting will reduce most pathogens if a sufficient temperature is reached.
5.7.4. Summary
Table 5.13 summarises the upstream control measures that can be applied to reduce contaminants for dredging from inland waters. The strategies judged to be more effective for each contaminant are shown in bold.
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Table 5.13 Upstream control measures for contaminants in dredgings from inland waters Contaminants of concern Major source s Potential upstream control Practicality Effectiveness Justification Car wash water treatment GAC filters could possibly reduce Cr inputs Car washes High Medium (GAC filter) into wastewater treatment. Chromium Reducing levels in health Health supplements are likely to comprise only Human faeces Low Low supplements a small proportion of PTEs loading in faeces. Old pipework Replace metal pipework with The use of plastic pipework would Lead Medium Medium corrosion plastic pipework significantly reduce amounts of Pb in sludge. It is not possible to control Health supplements are likely to comprise only Faeces Low Low levels of PTEs in faeces a small proportion of PTEs loading in faeces. Plumbing Replace metal pipework with The use of plastic pipework would Medium Medium corrosion plastic pipework significantly reduce amounts of Cu in sludge. Represent only a small proportion of Cu in Reduce levels in feedstuffs High Low runoff. Copper Increase bioavailability in Represent only a small proportion of Cu in Medium Low animal diet runoff. Feedstuffs Use of combination between Represent only a small proportion of Cu in PTEs organic and inorganic minerals Low Low runoff. formulations Represent only a small proportion of Cu in Reduce period of animal intake Low Low runoff. It is not possible to control Health supplements are likely to comprise only Human faeces Low Low levels of PTEs in faeces a small proportion of PTEs loading in faeces. Plumbing Replace metal pipework with The use of plastic pipework would Medium Medium corrosion plastic pipework significantly reduce amounts of Zn in sludge. Represent only a small proportion of Zn in Reduce levels in feedstuffs High Low runoff. Zinc Increase bioavailability in Represent only a small proportion of Zn in Medium Low animal diet runoff. Feedstuffs Use of combination between Represent only a small proportion of Zn in organic and inorganic minerals Low Low runoff. formulations Represent only a small proportion of Zn in Reduce period of animal intake Low Low runoff.
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Table 5.13 (cont.) Upstream control measures for contaminants in dredgings from inland waters Contaminants of concern Major source s Potential upstream control Practicality Effectiveness Justification Atmospheric PCBs, PCDD/Fs Measures already in place - - PCBs have been banned. deposition PAHs could possibly be reduced by using a Atmospheric PAHs Catch basin in motorways Medium Medium catch basin to recover sediments and deposition therefore PAHs sorbed onto these. Separation between urine and faeces using the NoMix technology would significantly Urine separation (NoMix reduce levels of pharmaceuticals in sludge. Medium Medium technology) Although this approach would not be practical for all households it could be locally applied (e.g. hospitals). Doctors are most likely to prescribe the most Urine and faeces Risk classification schemes Medium Medium efficacious treatment regardless of the environmental impact. This might involve using schemes which Benign-by-design drugs Low Medium incentivise industry to find these more Organic attractive and several years of research. compounds Several more years of research are needed for Promotion of greener drugs Medium Medium the development of greener drugs. Pharmaceuticals Take-back schemes are the most practical Take-back schemes for safe High Medium approach since they are already used as a disposal method to dispose off drugs safely. The prescription of starter packs at the beginning of the treatment and review patient Alter prescription practices Medium High consumption over time might decrease amount of drugs disposed off. Improper disposal Doctors are most likely to prescribe the most Risk classification schemes Medium High efficacious treatment regardless of the environmental impact. This might involve using schemes which Benign-by-design drugs Low High incentivise industry to find these more
attractive and several years of research. Several more years of research are needed for Promotion of greener drugs Medium High the development of greener drugs.
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Table 5.13 (cont.) Upstream control measures for contaminants in dredgings from inland waters Contaminants of concern Major sources Potential upstream control Practicality Effectiveness Justification The use of more biodegradable materials would reduce levels for these organic compounds in effluents and therefore in . Development of substitutes and Detergent Medium High Some are already available and are LAS, DEHP, NP, and ecolabelling residues, ecolabelled. The use of these materials would other organic surfactants, be likely to significantly increase with contaminants plasticizers extensive public awareness campaigns. For legislation to be enforced several years are REACh Low High needed and therefore practicality is low for the present. Organic Educate farmers to choose less High Low Would not greatly reduce amounts in manure. compounds hazardous chemicals Restricting veterinary medicine use to sick Restrict veterinary medicines to High High animals would greatly reduce the amount of Prevention and sick animals Veterinary these organic compounds from manures. treatment of Improvement of animal medicines Less intensive rearing is not a practical animals husbandry practices (e.g. less Low Medium approach. intensive rearing) This might involve using schemes which Benign-by-design drugs Low High incentivise industry to find these more attractive and several years of resear ch. Keeping animals healthy and Sick or stressed animals are more likely to High High comfortable shed pathogens in their manure.
Animal Use of slotted floors for animal Pathogens NA Low Medium Pathogens not greatly reduced. faeces housing
Change of diet by addition of Would increase amounts of organic High High antimicrobials compounds instead.
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5.8. Abattoir waste
Waste in an abattoir derives from the unused animal parts, blood, and the animals gut contents. Waste also comes from washing of the animals and the equipment. Figure 5.7 shows the path of contaminants to land.
Figure 5.7 Abattoir waste stream
Contaminant Organic contaminants
-
POPs POPs Bulk Chemical Pharma- ceuticals Veterina ry drugs Pesticide s /Biocides personal care products Pathogen PTEs
Source Guts content Blood and Cleaning flesh chemicals
Production
Dissolved Air Flotation Separation of diseased animals
Processing
Compost Anaerobic Incineration digestion
Use
Land Application
Abattoir wastes are composted or subject to anaerobic digestion prior to land application. Dissolved air flotation separates the solid and effluent waste of the slaughtered animal so they can be disposed of separately. Blood is collected for separate treatment or processing (Defra, 2003).
5.8.1. PTEs
5.8.1.1. Sources
PTEs sources in abattoir waste are the same as sources for animal manure (section 5.3) and similar to animal manure, copper and zinc are the predominant PTEs present.
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5.8.1.2. Upstream control measures
Upstream control measures for the reduction of PTEs contamination would be the same as the ones suggested for livestock manure (section 5.3). These measures could reduce levels of PTEs in animals and also in manures. This information is included in the summary table (Table 5.14) to avoid repetition in the text.
Separation of the gut contents from the other waste- this measure reduces amounts of PTEs in the final waste stream and is an approach that is already being use.
5.8.1.3. Treatment
As with animal manure, there is no treatment proven to remove PTEs.
5.8.2. Organic Contaminants
5.8.2.1. Sources
In addition to veterinary medicines described in section 2.4.2.4, wash water chemicals used in abattoirs may contaminate the waste stream.
5.8.2.2. Upstream control measures
Upstream control measures for the reduction of organic compounds contamination would be the same as the ones suggested for livestock manure (section 5.3). This information is included in the summary table (Table 5.14) to avoid repetition in the text.
ERA of chemicals used as detergents - ERA of detergents used to clean abattoirs would allow educated choices on which chemicals to use and encourage research on alternatives.
Separate gut contents from other wastes – gut contents will have higher amounts of veterinary medicines when animals have been treated.
5.8.2.3. Treatment
Anaerobic digestion and composting will degrade some organic contaminants.
5.8.3. Pathogens
Many pathogens are found in abattoir waste such as Esherichia c. O157 , Salmonella, Listeria, Campylobacter, Cryptosporidium and Giardia .
5.8.3.1. Sources
Pathogens are present in animals as discussed in section 5.3.3.3 .
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5.8.3.2. Upstream control measures
Upstream control measures to reduce pathogen contamination in livestock manure (section 5.3.) will reduce pathogen content in abattoir waste. This information is included in the summary table to avoid repetition in the text.
5.8.3.3. Treatment
Digesting and composting the waste reduces the pathogenic content. The Animal By- product Regulations (EU, 2002) specify treatment of temperatures reaching 70 °C for one hour and waste having a maximum particle size of 12mm.
5.8.4. Summary
To reduce contamination of abattoir waste, upstream control measures suggested for livestock manure are likely to be the more appropriate for this waste stream and these are presented in Table 5.14.
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Table 5.14 Upstream control measures for reducing contaminants in abattoir waste Contaminants of concern Major source s Potential upstream control Practicality Effectiveness Justification Legislation has been applied and Reduce levels in feedstuffs High High levels remain too high. Still present in the diet but lower Copper Increase bioavailability in animal diet Medium High amounts. Gut contents from Use of combination between organic and Research is only available for pigs Low Medium PTEs feedstuffs inorganic minerals formulations and more evidence is needed. Reduce period of animal intake Low Medium More evidence needed. Zinc Separate gut contents from the Keep gut contents separated from other other abattoir waste reduces High High waste amounts of Cu and Zn in the final waste. Educate farmers to choose less hazardous Would not greatly reduce High Low chemicals amounts in animals. Restricting veterinary medicine use to sick animals would greatly Restrict veterinary medicines to sick animals High High reduce the amount of these organic compounds both in animals and in manure. Gut content - used Improvement of animal husbandry practices Less intensive rearing is not a Veterinary for Low Medium (e.g. less intensive rearing) practical approach. medicines prevention and This might involve using schemes treatment of animals Organic which incentivise industry to find Benign-by-design drugs Low High compounds these more attractive and several years of research. Separate gut contents from the Keep gut contents separated from other other abattoir waste reduces High High waste amounts of medicines in the final waste. LAS, NP and For legislation to be enforced other organic Detergent residues, several years are needed and compounds in REACh Low High surfactants therefore practicality is low for cleaning the present. products
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Table 5.14 (cont.) Upstream control measures for reducing contaminants in abattoir waste Contaminants of concern Major source s Potential upstream control Practicality Effective ness Justification Sick or stressed animals are more Keeping animals healthy and comfortable High High likely to shed pathogens in their manure. Pathogens NA Animal faeces Use of slotted floors for animal housing Low Medium Pathogens not greatly reduced. Would increase amounts of organic Change of diet by addition of antimicrobials High High compounds instead. NA – not available
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5.9. Textile industry waste
Textile manufacturing begins with making fibres from plants, animal wool, or synthetics. Fibres are made into yarn and then fabric to produce a variety of goods from designer clothing to carpets. Figure 5.8 demonstrates the migration of contaminants.
Figure 5.8 Textile industry waste stream
ContaminantOrganic contaminants
-
PTEs PTEs
POPs POPs Bulk Chemical Pharma- ceuticals Veterina ry drugs Pesticide s Biocides /personal care products Pathogen
Source
Dying washing and Natural fibre Synthetic fibre bleaching chemicals
Production
Yarn and fabric Yarn and fabric treatment Dyeing waste production waste waste
Processing
Compost Anaerobic Co -digestion Other digestion
Use
Land Application
5.9.1. PTEs
5.9.1.1. Sources
Dyes are the major source of metals into the textile processes (Davis and Rudd, 1999). Metals can be present for two reasons. First, metals are used as catalysts during dye manufacture and may be present as impurities. Second, in some dyes the metal is chelated with the dye molecule (IPPC, 2003a). For example, chromium may be used in wool dyeing as a mordant, which is a substance used to set dyes on fabrics by forming a coordination complex with the dye which then attaches to the fabric (Binkley et al., 2000). Zinc compounds are used to flameproof wool (DoE, 1996c). Other traces of metals may enter from raw fibre, water, corrosion, and chemical impurities (Binkley et al., 2000).
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5.9.1.2. Upstream control measures
A reference document on Best available Techniques (BAT) for the textile industry has been produced by the European Commission (IPPC, 2003a). Major sources of PTEs in textile waste are from the use of dyes.
Upstream control measures for the textile industry are presented below.
Reduce the amount of PTEs in dyes – these are present in dyes as impurities or used within the dyeing process as catalysts. To reduce PTEs in the textile industry starting products should be carefully selected and these would reduce impurities. Substitution of PTEs as reaction catalysts by other substances would reduce the amount of PTEs in dyeing waste. This would involve finding substitutes for PTEs and this might require several years; however, it would be an effective measure to reduce PTEs contamination in waste.
Separate dyeing and post-dyeing waste from other waste streams- keeping waste streams with PTEs separate will avoid contamination of other sludges by PTEs, as these are only present in dyeing and post dyeing waste. This is the most practical and effective approach.
Environmental risk assessment of the treatments used – this would provide data to choose the best practice techniques and provide guidelines or legislation to limit the use of metals within the textile industry. However, this approach might also require several years to be applied.
5.9.1.3. Treatment
Electrolysis could recover the metals especially as they will be in solution, but no literature currently exists on proven techniques.
The quality of the sludge can be improved during the treatment process; chemical products such as chromium and copper salts are being replaced by products with lower environmental impact on the water quality or that are more readily biodegradable.
5.9.2. Organic Contaminants
5.9.2.1. Sources
Raw material fibres are likely to contain pesticides or/and other preparation agents. For example, fleeces from sheep may contain traces of sheep dip chemicals.
During production and treatment potential chemical pollutants are added. Processes are dependent on specific textiles and include dyes, pesticides, special finishes, flame retardants, and insect proofers. Public fashion demand can drive choice of dyes and types of material (Correia et al., 1994).
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5.9.2.2. Upstream control measures
The Ecological and Toxicological Association of the Dyestuffs Manufacturing Industry (ETAD) aims to minimize contamination of the environment (Robinson et al., 2001) and REACh (2007) require environmental risk assessment of chemicals before new releases. This does not mean that older chemicals are assessed and this is an area for further study.
Substitution of persistent chemicals - BAT suggested by the Integrated Pollution Prevention and Control (IPPC) follows certain principles in the selection of chemicals: Where it is possible to achieve the desired process without the use of chemicals then their use should be avoided; and Where this is not possible, chemicals that pose a lowest environmental risk should be used when available.
Separate waste from processes that use persistent chemicals - similarly to metal contamination, any waste from a process with persistent chemicals should be kept separate. Waste effluent can be recycled and the treatment chemicals recovered, which reduces contaminants in waste.
BAT for the substitution of hazardous chemicals in textile industry are presented in Table 5.15.
Table 5.15 BAT for the substitution of hazardous chemicals in the textile industry (IPPC, 2003a) Chemical BAT Surfactants Substitute alkylphenol ethoxylates and other hazardous surfactants with susbtitutes that (e.g. are readily biodegradable or bioeliminable in the waste water treatment plant and do not alkylphenolethoxylates) form toxic metabolites (e.g. alcohol ethoxylates) Complexing agents Avoid or reduce the use of complexing agent in pretreatment and dyeing processes by a (e.g. EDTA) combination of: - softening of fresh water to remove the iron and the hardening alkaline-earth cations from the process water; - using a dry process to remove coarse iron particles from the fabric before bleaching . This treatment is convenient when the process starts with an oxidative/desizing step, otherwise a huge amount of chemicals would be required to dissolve the coarse iron particles in a wet process. However, this step is not necessary when an alkaline scouring treatment is carried out as a first step before bleaching; - removing the iron that is inside the fibre using acid demineralisation, or better, nonhazardous reductive agents before bleaching heavily contaminated fabrics; and - applying hydrogen peroxide under optimal controlled conditions. select biodegradable or bioeliminable complexing agents Antifoaming agents minimise or avoid their use by: - using bath-less air-jets, where the liquor is not agitated by fabric rotation; - re-using treated bath; and select anti-foaming agents that are free from mineral oils and that are characterised by high bioelimination rates.
Careful selection of raw materials - currently textile manufacturers are not well informed about the quality and quantity of substances applied in the fibre during upstream processes (e.g. preparation agents, chemicals, knitting oils). For example,
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fleeces from sheep may contain traces of sheep dip. Patterson et al. (2004) suggests three methods for reducing pollution from sheep dip chemicals: Test incoming wool and only accept it if suitable; Accept only wool with either lipophiphilic or hydrophilic pesticides to ensure the pesticide is removed into either the aqueous or solid waste; and Ensure degradation of the pesticide before acceptance by using with-holding times between dipping and shearing.
Table 5.16 lists identified BAT for some raw materials to prevent at the source that pollutants in the raw material fibre enter the finishing process (IPPC, 2003a).
Table 5.16 BAT for the selection of incoming fibre materials (IPPC, 2003a) Raw material BAT Man-made fibres - select material treated with low -emission and biodegradable /b ioeliminable preparation agents. Cotton - select material sized with low add-on techniques (pre-wetting of the warp yarn) and high-efficiency bioeliminable sizing agents; - use the available information to avoid processing fibre material contaminated with the most hazardous chemicals such as pentachlorophenol; and - use organically grown cotton when market conditions allow. Wool - use the available information to avoid processing fibre material contaminated with the most hazardous chemicals such as OC pesticides residues; - minimise at source any legally used sheep ectoparasiticides by encouraging the development of low pesticide residue wool by continuing dialogue with competent bodies responsible for wool production and marketing in all producing countries; and - select wool yarn spun with biodegradable spinning agents instead of formulations based on mineral oils and/or containing APEO.
5.9.2.3. Treatment
The nature of dyes is to resist decomposition so that they stay bright and colourful. Robinson et al. (2001) reviewed chemical, physical and biological treatments of textile waste containing dyes. Table 5.17 summarises chemical and physical methods. Sorption to wood chips followed by treatment with white rot fungi is the optimum treatment as the wood chips provide an ideal substrate for the fungi and then it can be digested before land spreading (Robinson et al., 2001).
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Table 5.17 Chemical and Physical treatments of textile waste (Robinson et al., 2001).
Biological treatments perform well at degrading various dyes. Anaerobic digestion was found to be effective for AZO dyes, but co-digesting may be necessary to provide enough carbon to begin the process. Surfactants that are present in the effluent can inhibit anaerobic digestion depending on concentration (Feitkenhauer and Meyer, 2002).
5.9.3. Pathogens
5.9.3.1. Sources
Wool and plants may introduce pathogens into the textile processes. Pathogens might be present in waste from fibre production but not in wastes further down the manufacturing line.
5.9.3.2. Treatment
The dry dust, dirt, hair and vegetable matter etc from raw materials in fibre production is composted before land application to remove pathogens.
5.9.4. Summary
Table 5.18 summarises the upstream control measures for reducing contaminants from textile industry waste. Measures that have been judged to be more effective are shown in bold.
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Table 5.18 Upstream control measures for reducing contaminants in textile industry waste. Contaminants of concern Major source s Potential upstream control Practicality Effectiveness Justification Reduce amounts of metals in dyes Low High Several years might be needed. Separation of dyeing and post- dyeing wastes from the other Separate wastes that contain PTEs. High High waste streams reduces PTEs Chromium Dyes contamination of the final waste. Several years are needed and ERA of treatments used Low High therefore practicality is low for the present. PTEs Reduce amounts of metals in dyes Low High Several years might be needed. Separation of dyeing and post- dyeing wastes from the other Separate wastes that contain PTEs High High Dyes waste streams reduces PTEs Zinc Flameproof wool contamination of the final waste. Several years are needed and ERA of treatments used Low High therefore practicality is low for the present. Substitution of persistent chemicals by others less Surfactants, Substitution of persistent chemicals. High High hazardous reduces amount of complexing agents, Processes used organic compounds in wastes. antifoaming agents, These are already available. Flame retardants Separate the wastes from the different Less effective than chosen Organic Medium High processes. measure. compounds Biopesticides are biodegradable pest management tools based on Use of biopesticides High High beneficial organisms and made Biocides Animal treatment with biologically based active ingredients. Use/disposal guidance Medium Medium Not as effective as chosen option. ERA – environmental risk assessment
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Table 5.18 (cont.) Upstream control measures for reducing contaminants in textile industry waste. Contaminants of concern Major source s Potential upstream control Practicality Effectiveness Justification For legislation to be enforced several years are needed and Biocides (cont.) Animal treatment REACh Low High therefore practicality is low for Organic the present. compounds Testing of raw material or Preparation agents, Raw materials Careful selection of raw materials. High High incoming fibres before accepting knitting oils for processing.
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5.10. Tannery and leather waste
The leather and tannery industry takes animal skins together with bits of flesh and dirt and turns them into preserved, flexible, attractive leather. This is achieved by pre-tanning or beamhouse processes where hair, dirt and flesh are removed, and the tanning and finishing processes which include dyeing, trimming and protecting the leather. Figure 5.9 illustrates the processes involved.
Figure 5.9 Tannery and leather waste stream
Contaminant Organic contaminants
-
POPs POPs Bulk Chemical Pharma- ceuticals Veterina ry drugs Pesticide s /Biocides personal care products Pathogen PTEs
Source
Chemicals Hides, skin, flesh, dirt, hair
Production
Pre-tanning / Beamhouse Tanning waste Finishing waste waste
Processing
Compost Anaerobic Co -digestion digestion
Use
Land Application
5.10.1. PTEs
5.10.1.1. Sources
Cr is used as a tanning agent and is the main PTE associated with the leather industry. Tanning agents are chosen for the particular properties they give leather, and Cr is the most popular.
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5.10.1.2. Upstream control measures
Separation of wastes containing PTEs- if Cr is used for tanning, separation of waste before tanning allows that wastes, (e.g. hairs and trimmings), to be used and composted without contamination from the heavy metal.
Substitution of Cr - to reduce contamination of tannery and leather waste some substitutes are available: 20 to 35% of the fresh Cr input can be substituted by recovered chrome (IPPC, 2003b); Gluaraldehyde performs as a good alternative to Cr tanning giving better leather properties than other alternatives such as iron-complexes, aluminium options, and titanium and synthetic resins (Chakraborty et al., 2008); and Aluminium sulphate and vegetable tannin’s (e.g. Acacia nilotica ssp.tomentosa ) are also shown to have good leather properties (Haroun et al., 2008).
5.10.1.3. Treatment
Due to costs of treatments and pollution control Cr is often recovered and recycled. Complete recovery of chrome salts can be achieved with ultrafiltration (Scholz and Lucas, 2003). Katsifas et al. (2004) studied the biodegradation of Cr shavings using Aspergillus carbonarius isolate in solid state fermentation experiments. A 97% liquefaction of the tannery waste was achieved and the liquid obtained was used to recover Cr. A proteinaceous liquid was also obtained with the potential to be applied to land.
If high levels of Cr (in the proposed EU regulation for sludge this is 1000 mg/kg dry matter) are present in the waste it must be disposed of and not used for landspreading. However, Cr, Cd, and Pb concentrations all decrease during composting, probably due to leaching of the mobile metals; but Cu and Zn do not leach (Haroun et al., 2007). Ahmed et al. (2007) also reported loss of Cr during composting through leachate. Containing the compost to collect the leachate is necessary in this case to avoid contaminating the composting site.
Anaerobic digestion of tannery waste is also possible. However, vegetable tanning agents were shown to inhibit the methanogenic stage of anaerobic digestion of tannery waste, while Cr tannins had much less effect (Bajwa and Forster, 1988).
5.10.2. Organic Compounds
5.10.2.1. Sources
All the organic chemicals used in the processes serve a purpose and cannot be simply removed (IPPC, 2003b): biocides are used in the curing, soaking, pickling, tanning and post-tanning processes; Halogenated organic compounds are established use in tanneries; however, they can be substituted with one exception – the dry-degreasing of Merino sheepskins;
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Surfactants are used in processes such as soaking, liming, degreasing, tanning and dyeing. The most used surfactant is nonylphenolethoxilate because of its emulsifying property; and Complexing agents such as EDTA and NTA are used as sequestering agents.
The consumption level of the main process chemicals, tanning agents and auxiliary chemicals for a conventional tanning process for salted, bovine hides is shown in Table 5.19.
Table 5.19 Level of chemicals used to process salted bovine hides (IPPC, 2003b) Chemical consumption % Standard inorganic (without salt from curing, acids, bases, sulphides, 40 ammonium-containing chemicals) Tanning chemicals (chrome, vegetable and alternative tanning agents) 23 Finish chemicals (pigments, special effect chemicals, binders and 10 crosslinking agents) Fat liquoring agents 8 Standard organic, not mentioned below (acids, bases, salts) 7 Organic solvents 5 Dyeing agents and auxiliaries 4 Enzyme 1 Surfactants 1 Biocides 0.2 Others (sequestering agents, wetting agents, complexing agents) ? TOTAL 100
5.10.2.2. Upstream control measures
Upstream control measures to reduce organic compounds contamination in tannery and leather waste are presented below.
Restrict amount of organic compounds used- chemicals are used in excess to ensure good penetration especially the beamhouse processes. All the treatments are expensive and so the chemicals are recovered and reused. Up to 90% of beamhouse chemicals and vegetable tannins can be recovered using microfiltration. This is an effective approach to reduce contaminants going to the waste (Scholz and Lucas, 2003).
Research of alternative treatments to find less persistent options- to achieve this environmental risk assessment should be used with best available techniques. Lazzeri et al. (2006) confirmed that mineral oils used in both tannery and textile industries could be replaced by High Oleic Sunflower Oil (HOSO) which has a higher biodegradability. To apply this change requires no modification of facilities.
Substitution of the most harmful chemicals used during the tanning process- BATs substitutes that are less harmful and can be used in the tanning industry are listed in Table 5.20.
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Table 5.20 Substances currently used and BATs substitutes (IPPC, 2003b) SUBSTANCE BAT SUBSTITUTE Biocides Products with the lowest environmental and toxicological impact, used at the lowest level possible e.g. sodium- or potassium-di- methyl-thiocarbamate Halogenated organic compounds They can be substituted completely in almost every case. This includes substitution for soaking, degreasing, fat liquoring, dyeing agents and special post-tanning agents -Exception- the cleaning of Merino sheepskins Organic solvents Finishing: (non-halogenated) • Aqueous-based finishing systems -Exception: if very high standards of topcoat resistance to wet- The finishing process and the rubbing, wet-flexing and perspiration are required degreasing of sheepskins are the major • Low-organic solvent-based finishing systems areas of relevance. • Low aromatic contents Sheepskin degreasing: • The use of one organic solvent and not mixtures, to facilitate possible re-use after distillation Surfactants e.g. alcohol ethoxylates, where possible APEs such as NPEs Complexing agents EDDS and MGDA, where possible EDTA and NTA Ammonium deliming agents Partially with carbon dioxide and/or weak organic acids Dyestuffs De-dusted or liquid dyestuffs • High-exhausting dyes containing low amounts of salt • Substitution of ammonia by auxiliaries such as dye penetrators • Substitution of halogenic dyes by vinyl sulphone reactive dyes Fat liquoring agents Free of agents building up AOX -Exception: waterproof leathers • Applied in organic solvent-free mixtures or, when not possible, low organic solvent mixtures • High-exhausting to reduce the COD as much as possible Finishing agents for topcoats, binders • Binders based on polymeric emulsions with low monomer (resins) and cross-linking agents content • Cadmium- and lead-free pigments and finishing systems Others: Free of agents building up AOX - Water repellent agents - Exception: waterproof leathers - Brominated and antimony containing • Applied in organic solvent-free mixtures or, when not possible, flame retardant low organic solvent mixtures • Free of metal salts - Exception: waterproof leathers • Phosphate-based flame retardants APEs – alkyl phenol ethoxylates NPEs – nonylphenol ethoxylates NTA – nitrilo triacetate EDDS- ethylene diamine disuccinate MGDA – methyl glycine diacetate
5.10.2.3. Treatment
Activated sludge and co-composting can be used to treat tannery sludge. However after activated sludge treatment it was found that the dehairing sludge toxicity was not fully removed. The resulting toxicity was suspected to be caused by chloride and ammonia (Vidal et al., 2004). Another complication is that waste from dehairing does not compost by itself,
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or with de-inking sludge from paper mill waste, but sewage sludge did improve the co- composting treatment (Barrena et al., 2007).
Use of hair-save practices- hair can be removed by high organic chemical dissolving processes or hair-save practices, which use less contaminant and produce a compostable by-product. Treatment of the wastewater from dissolving hairs is more expensive so the hair-save practices have become more popular and use less organic compounds (Barrena et al., 2007).
5.10.3. Pathogens
5.10.3.1. Sources
Pathogens may be present on the hides and remnant flesh at the very early stages. The chemicals and toxic environment of the tanning processes will eliminate pathogens, and pathogens are not a high risk in this waste stream.
5.10.3.2. Treatment
If any pathogens survive, they will be reduced by composting.
5.10.4. Summary
Table 5.21 summarises the upstream control measures for reducing contaminants in the tanning and leather waste. Upstream control measures judged more effective are presented in bold.
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Table 5.21 Upstream control measures for reducing contaminants in tannery and leather waste. Contaminants of concern Major source s Potential upstream control Practicality Ef fectiveness Justification Chromium can be substituted by Substitution of chromium High High biodegradable materials that are PTEs Chromium Tanning agent already available. Less effective than chosen Separate wastes that contain chromium High High approach. Biopesticides are biodegradable pest management tools based on Biocides Animal treatment Use of biopesticides High High beneficial organisms and made with biologically based active ingredients. Restrict amounts of organic compounds used in Less effective than chosen Medium High Organic the processes. approach. AOX, organic compounds Substitution of persistent solvents, chemicals by others less hazardous complexing agents, Processes used Substitution of persistent chemicals. High High reduces amount of organic surfactants, compounds in wastes. These are dyestuffs, fat already available. liquoring agents Research of alternative treatments that use less Several years might be needed for Low High persistent contaminants. the application of this measure.
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5.11. Waste from food and drinks preparation
The food and drink industry produces product-specific wastes with different characteristics. Some are primary production wastes e.g. dairy, sugar beet and brewery industries, and some secondary from semi-processed products e.g. jam and confectionary. The waste stream of the food and drinks production industry is complex but can be generalised for this purpose (Figure 5.10).
Figure 5.10 Waste from food and drinks preparation stream
Contaminant Organic contaminants
-
POPs Bulk Chemical Pharma- ceuticals Veterina ry drugs Pesticide s /Biocides personal care products Pathogen PTEs
Source
Animal Plant Food / drink Cleaning Packaging additives chemicals
Production Bulk waste Processing Overproduction Packaging waste waste waste Waste water
Processing
Compost Anaerobic digestion
Use
Land Application
Darlington et al. (2009) describes a waste model applicable to the whole food industry using five waste categories: 1. Bulk waste – the inedible parts of the raw ingredients from animals and plants. 2. Waste water – the cleaning, preparation and cooking water. 3. Processing wastes – the unused, spoiled or rejected waste from processing. 4. Packaging wastes – plastic, glass and paper waste. 5. Overproduction waste – end of line, unfit, or unsellable waste.
These five waste categories are used instead of each specific food and drink product line. A separation is also evident between animal and plant derived waste. Animal waste falls under the Animal By-products legislation (EU, 2002) and must be dealt with accordingly. This
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section will not repeat investigating unprocessed animal products. Refer to livestock manure (section 5.3) and abattoir waste (section 5.7) for contaminant sources from animal waste, flesh, and blood.
5.11.1. PTEs
5.11.1.1. Sources
Some PTEs, such as Cd, Cu, Zn and Ni are present in vegetables. For example, potatoes, tomatoes, spinach, and mushrooms contain Cd, and potatoes also contain Zn and Cu.
PTEs should not be a primary concern of the food and drink industry. However, high inputs to soils have been found for Cd and Cu. A proportion is from the processing of some vegetables, such as potatoes, tomatoes and mushrooms. PTEs in dyes and inks may enter from packaging, and another minor source of PTEs is the inevitable wearing of machinery.
5.11.1.2. Upstream control measures
Upstream control measures for reducing the amounts of contaminants in waste from food and drink production are presented below.
Separate wastes - Sorting the packaging waste so that any with highly inked and dyed material with metal content is kept separate would avoid it contaminating the other waste streams. Also, the use of inks without metals would eliminate this source. This is judged as the most effective approach for reducing PTEs contamination in the final waste.
For reducing contamination from the processing of vegetables, no upstream control measures can be applied. However, this contamination is likely to only represent a small proportion of PTE contamination.
Maintain machinery in good condition – this would reduce any PTEs contamination from the wearing of machinery. However, this would only represent a small proportion of the contamination and would not be very effective.
5.11.1.3. Treatment
It would not be efficient to treat the waste packaging for the amount of metal present.
5.11.2. Organic Contaminants
5.11.2.1. Sources
Very few dangerous chemicals and pollutants are used in food manufacture (Darlington et al., 2009). Some cleaning chemicals, preservative chemicals, plastics for packaging, and pesticides, insecticides and fungicides will be present (Mardikar and Niranjan, 1995).
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5.11.2.2. Upstream control measures
Some upstream control measures for reducing organic contaminants in food and drink waste are presented below.
Environmental risk assessment of chemicals used – the environmental risk assessment of preservatives and pesticides added to vegetables, and to detergents and cleaning agents used in the food and drinks industry, would allow educated choices on which chemicals to use and encourage research on alternatives. The use of legislation, such as REACh, could enforce this measure. Practicality for this approach is judged low since several years are still needed for legislation to be enforced.
Separating waste streams – this ensures that pesticides in vegetable washing and cleaning chemicals do not contaminate the wastes from later in the process. This is judged the most effective approach to reduce levels of organic compounds in the final waste.
Alternatives for pesticides – biopesticides are an alternative to these persistent compounds. These are biodegradable pest management tools based on beneficial microorganisms, nematodes or other safe, biologically based active ingredients. This approach is the more effective way to reduce pesticide residues in vegetables.
5.11.2.3. Treatment
Anaerobic digestion and composting will breakdown some organic contaminants.
5.11.3. Pathogens
5.11.3.1. Sources
Pathogens are present in meat, eggs, plants and most foods. They cannot be avoided in food industry waste.
5.11.3.2. Upstream control measures
The use of cleaning chemicals and hygienic conditions integral to food processing will limit the pathogens during processing but not eliminate them. Therefore, the measure that can be applied is shown below.
Separation of the different wastes - keeping the packaging waste stream separate to the food and drink waste streams, the animal waste streams separate to the vegetable waste streams, and the raw separate from the processed streams will minimize cross contamination.
5.11.3.3. Treatment
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Waste of animal origin or waste that has come into contact with waste of animal origin must be treated in an approved facility for category 3 animal by-products (EU, 2002). The facility can either anaerobically digest or compost the waste but it must reach 70 °C for one hour and have a maximum particle size of 12mm. The plant material and parts of the packaging waste can be digested too.
5.11.4. Summary
Table 5.22 summarises the upstream control measures for reducing contaminants in the food and drink industry waste. Upstream control measures judged more effective are presented in bold.
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Table 5.22 Upstream control measures for reducing contaminants in the food and drink industry waste. Contaminants of concern Major source s Potential upstream control Practicality Effectiveness Justification No approaches have been Vegetables NA - - identified. Only a minor proportion of PTEs Wearing machinery Maintain machinery in good conditions High Low would be reduced. Cadmium An effective measure to keep the Separate the wastes from the different different contaminants separated Packaging High High processes. in the different waste streams to avoid cros s contamination.
No approaches have been PTEs Vegetables NA - - identified.
Only a minor proportion of PTEs Wearing machinery Maintain machinery in good conditions High Low Copper would be reduced.
An effective measure to keep the Separate the wastes from the different different contaminants separated Packaging High High processes. in the different waste streams to avoid cross contamination. Restrict amounts of organic compounds used in Less effective than chosen Medium High the processes. approach. Substitution of persistent Detergents and chemicals by others less hazardous Surfactants, LAS Substitution of persistent chemicals. High High cleaning products reduces amount of organic Organic compounds in wastes. compounds Several years might be needed for REACh Low High the application of this measure. An effective measure to keep the Separate the wastes from the different different contaminants separated Plastics Packaging High High processes. in the different waste streams to avoid cross contamination. NA – non available
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Table 5.22 (cont.) Upstream control measures for reducing contaminants in the food and drink industry waste. Contaminants of concern Major source s Potential upstream control Practicality Effectiven ess Justification Several years might be needed for REACh Low High the application of this measure. Organic Biopesticides are biodegradable Pesticides Vegetable washing pest management tools based on compounds Use of biopesticides High High beneficial organisms and made with biologically based active ingredients. An effective measure to keep the Separate the wastes from the different different contaminants separated Pathogens NA Food High High processes in the different waste streams to avoid cross contamination. NA – non available
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5.12. Waste from chemical and pharmaceutical manufacture
The industry of fine chemicals 1 includes the manufacture of dyes and pigments, plant health products and biocides, pharmaceutical products, organic explosives, organic intermediates, surfactants, flavours, plasticizers, etc (IPPC, 2006). Waste production from the manufacture of pharmaceuticals (as a representation of fine chemicals) is generalised and illustrated in Figure 5.11 (DoE, 1995).
Figure 5.11 Chemical and pharmaceutical manufacture waste stream
Contaminant Organic contaminants
-
ydrugs POPs POPs Bulk Chemical Pharma- ceuticals Veterina r Pesticide s Biocides / personal care products Pathogen PTEs PTEs
Source
Plants, animals, fungi Chemicals
Production Primary processes Secondary processes
Pre-processing Fermentation Mixed and waste waste other waste
Processing
Compost Anaerobic Other disposal digestion routes
Use
Land Application
Figure 5.11 shows three types of waste: 1. Processing raw materials from plants, animals and fungi produces waste that can be stabilised and used similarly to other animal and plant wastes. 2. Fermentation waste from primary processes is the main source of biomass (Gendebien et al., 2001). 3. In smaller plants and plants with primary and secondary processes waste streams are often mixed (DoE, 1995).
1 Fine chemicals are pure, single chemical substances that are commercially produced by chemical reactions into highly specialized applications.
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In the secondary processing of chemical and pharmaceutical manufacture, “bulking” ingredients are used, e.g. starches and sugars to make the chemicals into pills and medicines. The waste from these could also be used for soil amendment after digestion but no evidence was available in the existing literature.
Hazardous waste from chemical and pharmaceutical manufacture is not considered viable as an organic waste stream for land spreading. This may include test animals and plants, highly contaminated wastes, and wastes that would inhibit the digestion processes (Gupta, 2006).
5.12.1. PTEs
5.12.1.1. Sources
PTEs may be added as ingredients for the product, e.g. mineral supplements, or may enter from catalysts. The raw animal material could introduce small levels of PTEs.
5.12.1.2. Upstream control measures
Upstream control measures for the chemical and pharmaceutical industry are similar to those that have been presented for other waste types, such as the animal manure (section 5.3). The practicality and effectiveness of those measures are judged for the chemical and pharmaceutical waste industry and this information is presented on the summary (Table 5.23). These include:
Separation of waste streams - this ensures that any with PTEs contamination do not mix with less contaminated streams. It is in the nature of the industry to carefully control the ingredients and contents of the processes, so it is assumed that wastes with PTEs contamination could be identified and directed towards other disposal options.
Research on green chemistry techniques – these can be employed to find alternatives to PTEs in the manufacturing industry, e.g. alternative catalysts (Clark, 2006).
5.12.1.3. Treatment
Waste streams for landspreading from this industry are commonly stabilised by anaerobic digestion or composting which do not reduce PTEs levels.
5.12.2. Organic Compounds
5.12.2.1. Sources
The chemistry of fine organic intermediates shows an enormous diversity. However, the number of operations and processes used are similar. These include charging/discharging of reactants and solvents, inertisation, reactions, crystallisations, phase separations, filtrations, distillation and product washing (IPPC, 2006). The Food and Environment Research Agency 192
The key environmental issues of this industry are emissions of volatile organic compounds, wastewaters with potential high loads of non-degradable organic compounds, large quantities of spent solvents and non-recyclable waste (IPPC, 2006). Pharmaceutical residues might also be present in the final waste. Sources of organic compounds might also be brought into this industry through animals, plant and fungi.
5.12.2.2. Upstream control measures
Upstream control measures applied for animal manures (section 5.3) and plant waste (section 5.6) are also relevant for this waste stream. The practicality and effectiveness of those measures are judged for the chemical and pharmaceutical waste industry and this information is presented on the summary table and include:
Separation of waste streams ensures maximised use of potential to spread to land and less contamination. Knowing exactly what is in the waste stream from records of the processes involved allows careful choice as to whether they can be used on soil. This a practical approach since it is already in use and an effective measure to reduce contamination in the final waste stream.
Research into alternative pharmaceuticals and chemical treatments provide new information about less persistent chemical options. This is achieved through green chemistry techniques, environmental risk assessment and use of REACh data (Clark, 2006). However, in the manufacture of fine organic chemicals, the substitution of chemicals by less persistent chemicals is very difficult. Therefore, BATs are to segregate and pretreat the waste streams and dispose of mother liquors from halogenations and sulphachlorinations processes (IPCC, 2006). This approach would take several years to put in place since a lot of research is still needed.
5.12.2.3. Treatment
BAT for the manufacture of fine organic chemicals are the establishment of mass balances for volatile organic compounds on a yearly basis, to carry out a detailed waste stream analysis in order to identify the origin of the waste stream and a basic data set to enable management and suitable treatment of exhaust gases, waste water streams and solid residues (IPPC, 2006). Another BAT is the re-use of solvents as far as purity requirements allow. Waste is commonly stabilised using anaerobic digestion or composting. These treatments digest some organic contaminants whilst other contaminants may inhibit the process e.g. surfactants (Feitkenhauer and Meyer, 2002). Depending on the contents of the waste stream, the optimum process can be chosen to maximise effect and minimise contamination.
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5.12.3. Pathogens
5.12.3.1. Sources
As discussed in previous sections, pathogens have diffuse sources that are not controllable. They enter the process with raw material but will be eliminated as waste before reaching the primary and secondary processing stages to avoid contamination of the product.
5.12.3.2. Upstream control measures
The preparation of the plants, animals, and fungi will most likely occur at separate sites than the primary and secondary chemical processes. Therefore the waste streams can easily be kept separate. Any pathogens used to test products will be carefully controlled as hazardous materials by the industry and disposed of as such. Nevertheless, upstream control measures to reduce pathogen contamination before entering this industry are the same as that for plant waste (section 5.6) and for livestock manure (section 5.3). Practicality and effectiveness for those measures are judged for the chemical and pharmaceutical waste industry and this information is presented on the summary table to avoid repetition.
5.12.3.3. Treatment
Thermophilic treatment, either anaerobic digestion or composting will kill most pathogens.
5.12.4. Summary
Table 5.23 summarises the upstream control measures for reducing contaminants in the chemical and pharmaceutical industry waste. Upstream control measures judged more effective are presented in bold.
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Table 5.23 Upstream control measures for reducing contaminants in the chemical and pharmaceutical industry waste. Contaminants of concern Major source s Potential upstream control Practicality Effectiveness Justification Legislation has been applied and levels Reduce levels in feedstuffs High Medium remain too high. Copper With increased bioavailability of copper and zinc in animal diet, then it is likely that lower amounts are Increase bioavailability in animal diet Medium High Feedstufs needed in feedstuffs, which would therefore effectively reduce levels in PTEs manure. Zinc Use of combination between organic Research is only available for pigs and Low Medium and inorganic minerals formulations more evidence is needed. Reduce period of animal intake Low High More evidence needed. Separate the wastes from the An effective measure to treat these High High different processes. wastes in an appropriate way. All PTEs Processes used Several years are needed and therefore Green chemistry Low High practicality is low for the present . Educate farmers to choose less Would not greatly reduce amounts in High Low hazardous chemicals manure. Restricting veterinary medicine use to Restrict veterinary medicines to sick sick animals would greatly reduce the High High animals amount of these organic compounds Organic Veterinary Prevention and from manures. compounds medicines treatment of animals Improvement of animal husbandry Less intensive rearing is not a practical Low Medium practices (e.g. less intensive rearing) approach. This might involve using schemes which incentivise industry to find these more Benign-by-design drugs Low High attractive and several years of research.
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Table 5.23 (cont.) Upstream control measures for reducing contaminants in the chemical and pharmaceutical industry waste. Contaminants of concern Major sources Potential upstream control Practicality Effectiveness Justification Separate the wastes from the An effective measure to treat these Pharmaceuticals Processes High High different processes. wastes in an appropriate way. Biopesticides are biodegradable pest management tools based on Use of biopesticides High High beneficial organisms and made with biologically based active ingredients. Pesticides Plant treatment Use/disposal guidance Medium Medium Not as effective as chosen option. Organic compounds For legislation to be enforced several REACh Low High years are needed and therefore practicality is low for the present. For legislation to be enforced several REACh Low High years are needed and therefore Solvents Processes practicality is low for the present. Separate the wastes from the An effective measure to treat these High High different processes. wastes in an appropriate way. Sick or stressed animals are more Keeping animals healthy and High High likely to shed pathogens in their comfortable manure. NA Animal faeces Use of slotted floors for animal Pathogens not greatly reduced. Low Medium Pathogens housing Change of diet by addition of Would increase amounts of organic High High antimicrobials compounds instead. Separate the wastes from the An effective measure to treat these Fungi Plant High High different processes. wastes in an appropriate way. NA – non available
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5.13. Summary of Information
The strategies judged most effective for each individual contaminant of concern for each waste stream are summarised for PTEs, organic compounds and pathogens in Tables 5.24, 5.25 and 5.26, respectively. This information has been taken from the summaries at the end of each waste stream section. Dredgings from inland waters have not been included in the summary table since input to soil levels for all contaminants were much higher than for any other material.
For PTEs, where inputs to soils following the application of different materials were available and comparable for individual contaminants, materials with the highest PTEs input to soils were selected to build the table.
For organic compounds, inputs to soil following application were not comparable between the different materials. Therefore, for each individual contaminant, all materials that contained the organic compound have been included in Table 5.25 since it could not be judged which ones have the higher input to soils following landspreading.
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Table 5.24 Summary table for the most effective measure to reduce PTEs contamination according to highest input material. PTEs Waste type Major sources Potential upstream control Practicality Effectiveness Justification Separation of woods according to treatment Wood, bark and other Wood Separate woods according to Arsenic High High received e.g. SMARTWaste. This would increase plant waste treatment treatment received. the re -use, recycle and composting of wood waste. The use of Cd-free batteries is likely to greatly MSW Batteries Use of Cd-free batteries High High reduce Cd in MSW and these are already available. Using metal-free inks would reduce amount of PTEs in the waste ink produced by a printer; in the Paper and pulp waste Ink Use of metal-free inks High High printed materials that are landfilled or incinerated; Cadmium and in the sludge created during de-inking in paper recycling. An effective measure to keep the different Separate the wastes from the Food and drinks industry Packaging High High contaminants separated in the different waste different processes streams to avoid cross contamination. Car wash water treatment (GAC GAC filters could possibly reduce Cr inputs into Sewage sludge Car washes High High filter) wastewater treatment. MSW Cr in paper is mainly from inks. Thus, the usage of Ink Use of metal free inks High High metal-free inks would greatly reduce levels for Cr Paper and pulp waste in MSW. Separation of woods according to treatment Wood, bark and other Wood Separate woods according to Chromium High High received e.g. SMARTWaste. This would increase plant waste treatment treatment received the re-use, recycle and composting of wood waste. Separation of dyeing and post-dyeing wastes from Textile industry Dyes Separate wastes that contain PTEs High High the other waste streams reduces PTEs contamination of the final waste. Tannery and leather Chromium can be substituted by biodegradable Tanning agent Substitution of chromium High High industry materials that are already available. Plumbing Replace metal pipework with The use of plastic pipework would significantly Sewage sludge Medium High corrosion plastic pipework reduce amounts of Cu in sludge. Livestock manure With increased bioavailability of copper and zinc in Copper Increase bioavailability in animal animal diet, then it is likely that lower amounts are Abattoir waste Feedstuffs Medium High Chemical and diet needed in feedstuffs, which would therefore pharmaceutical industry effectively reduce levels in manure.
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Table 5.24 (cont.) Summary table for the most effective measure to reduce PTEs contamination according to highest input material. PTEs Waste type Major sources Potential upstream control Pract icality Effectiveness Justification Using metal-free inks would reduce amount of PTEs in the waste ink produced by a printer; in the Paper and pulp waste Ink Use of metal-free inks High High printed materials that are landfilled or incinerated; in the sludge created during de-inking in paper recycling. Copper Separation of woods according to treatment (cont.) Wood, bark and other Wood Separate woods according to High High received e.g. SMARTWaste. This would increase plant waste treatment treatment received. the re -use, recycle and composting of wood waste. An effective measure to keep the different Separate the wastes from the Food and drinks industry Packaging High High contaminants separated in the different waste different processes. streams to avoid cross contamination. Mercury Gypsum Unknown NA - - NA Drinking water sludge Nickel Unknown NA - - NA Food industry Batteries, wood Recycling Lead mainly comes from batteries for which there MSW preservatives, (e.g. stewardship incentive High High are already available schemes for recycling. biocides schemes) Using metal-free inks would reduce amount of Lead PTEs in the waste ink produced by a printer; in the Paper and pulp industry Ink Use of metal-free inks High High printed materials that are landfilled or incinerated; in the sludge created during de-inking in paper recycling. Plumbing Replace metal pipework with The use of plastic pipework would significantly Sewage sludge Medium High corrosion plastic pipework reduce amounts of Zn in sludge. Livestock manure With increased bioavailability of copper and zinc in Increase bioavailability in animal animal diet, then it is likely that lower amounts are Abattoir waste Feedstuffs Medium High Zinc Chemical and diet needed in feedstuffs, which would therefore pharmaceutical industry effectively reduce levels in manure. Dyes Separation of dyeing and post-dyeing wastes from Textile industry Flameproof Separate wastes that contain PTEs High High the other waste streams reduces PTEs wool contamination of the final waste. NA – not available
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Table 5.25 Summary table for the most effective measures to reduce organic compounds contamination according to input materials. Organic Waste type Major sources Potential upstream control Practicality Effectiveness Justification compound Using Totally Chlorine Free (TCF) and Elementary Chlorine products Use of non-chlorinated Chlorine Free (ECF) bleaching processes reduces Paper and pulp industry used in the High High compounds concentrations of chlorinated organic substances bleaching process AOX in waste. Substitution of persistent chemicals by others less Tannery and leather Substitution of persistent Processes used High High hazardous reduces amount of organic compounds industry chemicals. in wastes. These are already available Creosote, preservatives, Separation of woods according to treatment Wood, bark and plant Separate woods according to micro-emulsion, Wood treatment High High received e.g. SMARTWaste. This would increase waste treatment received. paint and stain, the re-use, recycle and composting of wood waste. and varnish The use of more biodegradable materials would Detergent Sewage sludge reduce levels for these organic compounds in residues, Development of substitutes sludge. Some are already available and are plasticizers, Medium High and ecolabelling ecolabelled. The use of these materials would be personal care Flame retardants MSW likely to significantly increase with extensive products public awareness campaigns. Substitution of persistent chemicals by others less Substitution of persistent Textile industry Processes used High High hazardous reduces amount of organic compounds chemicals. in wastes. These are already available The use of more biodegradable materials would Sewage sludge reduce levels for these organic compounds in Detergent Development of substitutes sludge. Some are already available and are LAS, DEHP, NP residues, Medium High and ecolabelling ecolabelled. The use of these materials would be plasticizers MSW likely to significantly increase with extensive public awareness campaigns. PAHs could possibly be reduced by using a catch Atmospheric PAHs Sewage sludge Catch basin in motorways Medium Medium basin to recover sediments and therefore PAHs deposition sorbed onto these. PCBs Atmospheric Measures already in place (e.g. PCBs have been Sewage sludge Measures already in place - - PCDD/Fs deposition banned).
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Table 5.25 (cont.) Summary table for the most effective measures to reduce organic compounds contamination according to input materials. Organic Waste type Major sources Potential upstream control Practicality Effectiveness Justification compound Wood, bark, and plant Plant treatment Biopesticides are biodegradable pest management waste Use of biopesticides High High tools based on beneficial organisms and made Pesticides/Biocides Food and drink industry Vegetable washing with biologically based active ingredients. Careful selection of raw Testing of raw material or incoming fibres before Textile industry Raw materials High High materials. accepting for processing. Separation between urine and faeces using the NoMix technology would significantly reduce Urine separation (NoMix Sewage sludge Urine and faeces Medium High levels of pharmaceuticals in sludge. Although this technology) approach would not be practical for all households it could be locally applied (e.g. hospitals). Pharmaceuticals Take-back schemes are the most practical Sewage sludge Take-back schemes for safe Improper disposal High High approach since they are already used as a method disposal MSW to dispose off drugs safely. Chemical and Separation of the wastes from An effective measure to treat these wastes in an Processes High High pharmaceutical industry the different processes. appropriate way. An effective measure to keep the different Separate the wastes from the Plastics Food and drinks industry Packaging High High contaminants separated in the different waste different processes. streams to avoid cross contamination. Preparation Careful selection of raw Testing of raw material or incoming fibres before agents, knitting Textile industry Raw materials High High materials. accepting for processing. oils Substitution of persistent chemicals by others less Tannery and leather Substitution of persistent Processes used High High hazardous reduces amount of organic compounds industry chemicals. Solvents in wastes. These are already available. Chemical and Separation of the wastes from An effective measure to treat these wastes in an Processes High High pharmaceutical industry the different processes. appropriate way. The use of more biodegradable materials would reduce levels of these organic compounds in Development of substitutes sludge. Some are already available and are Surfactants Sewage sludge Detergent residues Medium High and ecolabelling ecolabelled. The use of these materials would be likely to significantly increase with extensive public awareness campaigns.
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Table 5.25 (cont.) Summary table for the most effective measures to reduce organic compounds contamination according to input materials. Organic Waste type Major sources Potential upstream control Practicality Effectiveness Justification compound Textile industry Substitution of persistent chemicals by others less Substitution of persistent Surfactants Processes used High High hazardous reduces amount of organic compounds Tannery and leather chemicals. industry in wastes. These are already available. Complexing Textile industry Substitution of persistent chemicals by others less agents, Substitution of persistent Processes used High High hazardous reduces amount of organic compounds antifoaming Tannery and leather chemicals. in wastes. These are already available. agents, industry Prevention and Restricting veterinary medicine use to sick animals Veterinary Livestock manure Restriction of veterinary treatment of High High would greatly reduce the amount of these organic medicines medicines to sick animals Abattoir waste animals compounds from manures. Substitution of persistent chemicals by others less Dyestuffs, fat Tannery and leather Substitution of persistent Processes used High High hazardous reduces amount of organic compounds liquoring agents industry chemicals. in wastes. These are already available.
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Table 5.26 Summary table for the most effective measures to reduce pathogen contamination according to input materials. Pathogens Waste type Major sources Potential upstream control Practicality Effectiveness Justification Livestock manures Animals kept healthy and Sick or stressed animals are more likely to shed Abattoir waste Animal faeces High High comfortable pathogens in their manure. Chemical and NA pharmaceutical industry An effective measure to keep the different Separate the wastes from the Food and drink industry Food High High contaminants separated in the different waste different processes streams to avoid cross contamination. Waste wood, bark, and This will avoid contamination of wastes with fungi Plant, wood Carefully select raw material High High other plant material or plant pathogens. Fungi Chemical and Separate the wastes from the An effective measure to treat these wastes in an Plant High High pharmaceutical industry different processes. appropriate way. NA – not available
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5.14. Interpretation of information
The individual upstream control options from Tables 5.24, 5.25, and 5.26, and information presented in the waste stream sections can be interpreted into seven over-arching options applicable to a number of the different waste streams.
1. Sort and separate waste streams to reduce cross contamination of wastes. This upstream control measure has been identified as the most effective measure to reduce PTEs in the food and drinks industry, to reduce organic contaminants in wood, bark and plant waste, and to reduce both organic compounds and pathogens in the chemical and pharmaceutical industry and in the food and drink industry. For other waste types, although this measure has not been selected as the most effective, contamination in the final waste can be reduced in all cases. For example, source separation of municipal waste and separation of waste streams in industrial processes. The earlier different waste streams are separated within the process, the less volume becomes contaminated and needs treatment. Kerbside collections are increasing for MSW. Charging for collection of unsegregated waste would improve the performance of kerbside collection. But, this is only feasibly if the infrastructure to collect the separated waste is in place. Another example is the textile and tannery and leather industries, where separating waste streams can isolate contamination from specific processes such as tanning or dyeing. However, waste stream separation may require infrastructure or production process changes that may be possible for large companies but not for smaller ones.
2. Substitution of persistent compounds, where alternative (less persistent) chemicals are currently available.
This upstream control measure has been selected to be highly practical and effective in removing organic compounds contamination for the textile and tannery and leather industry where more biodegradable options are already available in most cases. This is also effective for reducing PTEs contamination in the paper and pulp, textile and tannery and leather industries, and in MSW waste streams where paper, textile and leather waste is present. Metal-free inks are currently available and can be used in the paper and pulp industry. Regarding the textile and tannery and leather industry, demand for metalliferrous dyes and inks are mostly for fashion rather than necessity so alternatives are possible without harm. Vegetable tannins perform well giving good leather qualities (Haroun et al., 2008), as does gluaraldehyde (Chakraborty et al., 2008), so there should be no need for the continuation of chrome as a tannin. However, the whole process must be considered because, for example, some vegetable tannins inhibit anaerobic digestion methanogenosis (Bajwa and Forster, 1988). Other dyes may also cause contamination and so a full risk assessment of the types of dyes should be performed so that the least hazardous can be used. For plant treatment, some pesticides can also be substituted by biopesticides, which are already available to be used as pest management tools and these are biodegradable.
3. Use Best Available Techniques in production processes.
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Using BAT means separating waste streams and applying environmental risk assessment (ERA) data to choose the least hazardous substances. ERA provides data to allow intelligent choices of substances to use in production processes. Comparisons can be made between substances and how they behave and degrade in the environment. REACh (2007) provides information on chemicals and their possible degradation products. REACh does not provide information on pharmaceuticals. At present regulations state that all new medicines must have an ERA but older ones do not (SI 1991/1914) . This should be rectified and all substances studied.
The PAS 100 compost quality protocol encourages the use of BAT to develop a product that is no longer classed as waste. The Environment Agency is working with the Waste & Resources Action Programme (WRAP) to develop more quality protocols for other waste streams. Approaching the waste management process as a whole system and waste as a by- product leads naturally into using BAT.
This strategy may require a change in thought processes in some sectors where quick profit is the primary motivation.
4. Restrict use of PTEs in animal feed by increasing the bioavailability of copper and zinc used, so that less is required.
There are already restrictions on how much copper and zinc can be added to animal feed, but improving the bioavailability of the metals will allow the limits to be lowered further. (EC, 2003; Revy et al., 2006). Studies have shown that a 35% reduction is possible without depriving the animal of supplements.
5. Compost or thermophilic anaerobic digestion to reduce some pathogens.
Pathogen inputs are very difficult to control. Treatment is the best option for reducing pathogens in the waste stream. Digestion is regulated by Animal by-product regulations (EU, 2002) and the quality protocol for compost, PAS100 (BSI, 2005). Unfortunately some contaminants can interfere with the digestion process.
6. Use legislation to enforce these strategies.
Examples of legislation that already positively affect these processes are the Water Framework Directive (EU, 2000b), the Animal By-products Regulations (EU, 2002), the regulation on batteries (EC, 1991a), and the Packaging Waste Directive (EU, 1994). Legislation can ensure that it is the producer’s responsibility for waste to have minimum contamination and that BAT and ERA are not ignored. Redefining organic waste destined for soil application as a “by-product” of processes would encourage consideration of its content. For example by-products of the food and drink industry that go directly into further food or drink processes are no longer classified as waste (AEA, 2007). There is always resistance to change especially when it requires extra effort and resources. Changing the approach to waste management will need legislation to back it up.
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7. Education of the public.
Each individual has a very small impact but by far the greatest contamination comes from all the individuals together. For example, metals in sewage sludge are the highest but each individual contributes a tiny amount. The public choosing chlorine-free paper helped make it a more common practice, and therefore reduced contamination levels in paper waste. By educating the public to the fate of metals and chemicals and contents of their consumables, they are able to make intelligent choices which can benefit the environment.
5.15. Significance
The aim of this work was to identify potential options for reducing the contaminants in organic waste streams that can be applied to land. Seven potential options have been identified across eleven waste streams. However, the current limitations and additional factors to be considered of these options must be acknowledged. These include:
This project did not include quantification of contaminant level or reduction, and no assessment of risk of each contaminant to soil. This will be important in any adoption of the strategies in the field. These strategies are only viable if the cost of implementing them does not exceed the gain. Costs of storing and/or transporting the bulky wastes limit their use. Waste application is limited by agricultural seasons and so the waste requires storage until it is the time to be spread. Smaller industries may not have facilities for the amount of storage required on site, and neither the producer of the waste, nor the farmer will want to incur the expense of storing it elsewhere. Similarly transport is only feasible within a certain distance from the site of production, due to expense and carbon footprint. Changing chemicals, waste handling procedures and treatment technologies may result in added expense. Installation of equipment (capital cost) and running it or transporting the waste to the treatment site may be a barrier to uptake. However, in the case of anaerobic digestion the process provides producers with a path to reduce and recover expenses from waste management. Anaerobic digestion not only makes biogas to use as fuel, but also stabilises and reduces the volume of waste. The reduced volume is easier to store and transport. The value of the organic waste to the soil must also be acknowledged. The nutrient levels and physical improvements are important qualities which vary with waste type and in excess they themselves can become contaminants. An approach that considers nutrient level, risk, cost, and the interest and practicalities of each individual industry is necessary. This “whole system” approach would improve these strategies and increase the significance of this work.
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5.16. The future
We are living in rapidly changing times. Predicted climate change is driving changes in waste management, and also in agriculture, energy production, and human behaviour. These changes will impact the quantity and quality of organic wastes and their fate.
5.16.1. Waste Management
Reducing waste is higher on the waste hierarchy than recycling waste. Industries are actively involved in reducing their waste streams, recovering chemicals, and minimising packaging (Defra, 2007b). However efficient the technology, there will still be waste, but over the coming years the volume and content will change.
5.16.2. Agriculture
Climate change predictions generally show the UK becoming warmer and drier (UKCIP, 2009). This will increase demand for irrigation. Industries that use a lot of water may change their waste and effluent treatment processes to use this water as irrigation and couple it with fertilisation. As fossil fuels become increasingly scarce the fertilisers made from them will increase in price, so organic waste fertilisers will become more popular.
5.16.3. Energy Production
The move towards sustainable energy production has increased the number of incineration and biogas plants in the UK. Incineration burns waste leaving ash with much less nutrient value for land than the digestate from biogas plants. Recovering waste for energy is lower down the waste hierarchy than recycling it to land. However, biogas production or anaerobic digestion produces both gas for energy and a digestate for soil application.
5.16.4. Population behaviour
The public can react badly to the smell and appearance of organic waste spread onto land. This issue will need to be addressed to gain support for increased landspreading. The population has purchasing power e.g. public awareness of chlorine use in the paper industry caused choice of chlorine free paper and motivated more change (Thompson et al., 2001). If the population takes climate change and sustainability seriously they will be able to drive changes in many industries, encourage Green Chemistry principles and reduce contamination and environmental damage.
5.17. Discussion
The most efficient way to reduce contamination in organic waste streams spread onto land is not to introduce the contaminant in the first place. The use of PTEs and persistent organic contaminants should be restricted especially as they are difficult to remove or treat once in a process. It is difficult to restrict entry of pathogens into waste streams, and the most efficient way to reduce them is thermophilic composting or anaerobic digestion.
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Controlling the inputs to products that are all destined to become waste eventually, controls the contents of the waste. It is important to increase the amount of data on chemical substances, their fate, transformation products, and risks through ERA and REACh, so that contamination can be minimised.
In a lot of industries, chemicals that are currently being used can be substituted by others that do not pose environmental concern. Therefore, these persistent chemicals should be substituted and this strategy could be enforced by the use of legislation, such as REACh.
Using best available techniques and best practices for waste management can be achieved by considering waste a by-product of another process. Waste can no longer be dumped and forgotten as it is becoming a valuable resource for fertiliser and energy. Legislation controls the use of waste and Quality protocols can be used to ensure the use of BAT and ERA in industry.
The public also need information about waste. The cumulative impact of each individual’s waste habits is massive and needs to be controlled by educating the public to allow then to make intelligent choices about products to buy and disposal techniques.
The information produced in this study provides a useful framework to identify sources and controls of contaminants in waste streams. It will be added to a larger project including quantification of contaminants and assessment of risk, so that priority strategies can be identified. Further work is suggested towards a “whole system” approach that considers benefits to soil and economics as well as risk.
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6. SUGGESTIONS FOR FURTHER STUDY
This study has attempted to review information of the inputs and concentrations of a range of contaminant types in a variety of waste types that could be applied to land. It has attempted to establish the relative importance of different waste types in terms of the inputs of specific contaminants to land and has explored ways in which contaminant levels could be reduced, if deemed to be of concern. However, due to a lack of information in many areas covered in the report, it is not yet possible to come up with definitive answers on the risks of different waste materials to the functioning of land and on how best to manage these. We therefore suggest that work in the future focuses on the following areas:
Consideration of a wider range of contaminant types – this study has only explored a handful of contaminants from different classes yet a much wider range of contaminants is likely to be present. It would be valuable if an inventory of major contaminants associated with different materials entering the waste stream was developed and methods for quantifying levels of these be developed. Transformation products should also be considered as in some instances these can pose a greater risk than the parent compound.
Consideration of a wider range of waste materials – this study has shown that good information is available for only a few materials. We need to develop a better understanding of the levels of contaminants in the other materials (e.g. compost and digestate) as well as future waste materials that might be applied to land.
Development of risk-based prioritisation schemes – it will be impossible to explore the risks of all waste and contaminant types to ecosystem functioning. It may therefore be appropriate to develop risk-based prioritisation approaches for identifying contaminants and waste materials of most concern. Prioritisation schemes of this type have been successfully applied in a number of other areas.
Development of a better understanding on the amounts of wastes materials applied to land – this work should consider both application rates in terms of tonnes/ha as well as information on the spatial degree of application and frequency of application to a site.
Establish the risks to the functioning of land – for contaminants of concern, a detailed assessment of the risks to land and associated water bodies is required. These assessments should not be done on a single contaminant basis but should also consider the potential for combination effects.
Study the benefits of different waste types in soil as well as the broader costs of waste material treatments and transport distances – this will then allow an informed decision to be made as to the suitability of a particular management strategy.
Integrate waste disposal into risk assessment schemes for synthetic substances – as more waste is likely to be applied to land in the future, it seems timely to integrate
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waste disposal aspects into environmental risk assessment schemes for synthetic substances. This is already done for veterinary compounds in manure and slurry and for some pharmaceuticals in sewage sludge.
Perform a social study on public awareness of waste and where it goes, followed by educational outreach about waste – ultimately this could assist in controlling the inputs of selected contaminants to waste streams.
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APPENDIX A Table A - 1 Prioritisation assessment for veterinary compounds that have the potential to enter the environment (Boxall et al., 2003) Potential to enter Hazard to terrestrial Therapeutic group Chemical group Major usage compounds Usage class the environment organisms Oxytetracycline High Low Tetracyclines Chlortetracycline High High Very high Tetracycline High Unknown Sulfadiazine High High Potentiated Trimethoprim High High Unknown sulphonamides Baquiloprim Unknown Unknown Amoxicillin High Unknown Procaine penicillin Unknown Very high β- Lactams High Procaine benzylpenicillin Unknown Unknown Clavunalic acid Unknown Unknown Antimicrobials Dihydrostreptomycin High Unknown Neomycin High Unknown Aminoglycosides High Apramycin High Unknownery high Flavomycin Unknown Unknown Tylosin High Low Monensin Unknown Very high Macrolides High Salinomycin sodium Unknown Very high Flavophospolipol Unknown Unknown Pleuromutlins Tiamulin Unknown Medium Medium Lincomycin Unknown Very high Lincosamides Medium Clyndamycin Unknown Unknown Pyrimidines (wormers) Morantel Medium Medium Unknown Endoparasiticides Cypermethrin High Unknown Pyrethroids (sheep dips) Medium Flumethrin High Unknown
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Table A-1 (cont.) Prioritisation assessment for veterinary compounds that have the potential to enter the environment (Boxall et al., 2003) Potential to enter Hazard to terrestrial Therapeutic group Chemical group Major usage compounds Usage class the environment organisms Triclabendazole Medium Unknown Azoles (Wormers) Fenbendazole Unknown Medium Unknown Endoparasiticides Levamisole Unknown Unknown Macrolide Ivermectin Medium Medium Very high endectins Amprolium Medium Very high Clopidol Unknown Unknown Endoparasiticides- Lasalocid sodium Unknown Unknown High coccidiostats Maduramicin Medium Very high Nicarbazin Unknown Unknown Robenidine hydrochloride Unknown Unknown Cephalexin Unknown Unknown Florfenicol High Very high Other antibiotics Tilmicosin Unknown Medium Unknown Oxolinic acid High Unknown Lido/lignocaine hydrochloride Unknown Unknown Endoparasiticides Others Nitroxynil Unknown Medium Unknown Enrofloxacin High Unknown Antimicrobials Fluoroquinolones Medium Sarafloxacin High Very high Dinmethicone Unknown Unknown Poloxalene Unknown Unknown Enteric preparations Toltrazuril Unknown Low Unknown Decoquinate Unknown Unknown Diclazuril Unknown Unknown
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Table A-1 (cont.) Prioritisation assessment for veterinary compounds that have the potential to enter the environment (Boxall et al., 2003) Potential to enter Hazard to terrestrial Therapeutic group Chemical group Major usage compounds Usage class the environment organisms Phosmet High Ectoparasiticides Unknown/low Unknown Piperonyl butoxide Medium Amidines (sheep Amitraz High Unknown Unknown dip) Delamethrin High High Unknown Cypromazine High Unknown Organophosphate Diazinon High High Very high
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APPENDIX B
Table A-2 Concentrations reported for organic contaminants in sewage sludge in the UK Compound CAS Sludge Range Mean Median Reference mg/kg dw μg/kg dw mg/kg dw μg/kg dw mg/kg dw μg/kg dw Alkyl and aromatic amine EDTA 150-43-6 NS 2.2-3.8 2.32 1.2 UKWIR, 1995 Carbonyl Nitroacetic acid 625 -75 -2 NS 1.4 -23 10.1 8.5 UKWIR, 1995 Chlorinated phenols Chlorophenol 25167-80-0 NS 0.0277-93.3 Wild a nd Jones, 1992 2,3-dichlorophenol NS 0.0004-0.072 0.024 0.005 UKWIR, 1995 2,4-dichlorophenol 120-83-2 AN 0.160 ± 0.006 W ilson et al., 1997 2,4-dichlorophenol 120-83-2 NS 0.35-2.6 1.36 1.25 UKWIR, 1995 2,4-dichlorophenol 120-83-2 AN 7.2 - 52.6 Wild et al., 1993 2,5 -dichlorophenol 583 -78 -8 AN 0.017± 0.001 Wilson et al., 1997 2,5 -dichlorophenol 583 -78 -8 NS 0.018 -0.4 0.1 0.059 UKWIR, 1995 2,5-dichlorophenol 583-78-8 AN 0.36 - 8.24 Wil d et al., 1993 2,6 -dichloroph enol 87 -65 -0 AN 0 - 0.74 Wild et al., 1993 2,6-dichlorophenol 87-65-0 NS 0.002-0.036 0.015 0.0135 UKWIR, 1995 3,4-dichlorophenol 95-77-2 AN 0.51 - 3.63 Wild et al., 1993 3,4-dichlorophenol 95-77-2 NS 0.025-0.18 0.065 0.054 UKWIR, 1995 3,5-dichlorophenol 59-35-5 AN 0.017± 0.001 Wil son et al., 1997 3,5 -dichlorophenol 59 -35 -5 AN 0.11 - 1.55 Wild et al., 1993 2,3,4,5 -tetrachlorophenol 4901 -51 -3 AN 0.005 ± 0.0001 Wilson et al., 1997 2,3,4,5-tetrachlorophenol 4901-51-3 AN 0.01 - 0.73 Wild et al., 1993 2,3,4,5-tetrachlorophenol 4901-51-3 NS 0.002-0.036 0.013 0.009 UKWIR, 1995 2,3,4,6-tetrachlorophenol 58-90-2 AN 0.08 - 0.64 Wild et al., 1993 2,3,4,6-tetrachlorophenol 58-90-2 NS 0.004-0.031 0.016 0.015 UKWIR, 1995 2,3,4,6-tetrachlorophenol 58-90-2 NS 0.004-0.031 0.016 0.015 UKWIR, 1995 2,3,5,6 -tetrachlorophenol 935 -95 -5 AN 0.04 - 0.36 Wild et al., 1993 2,3,5,6 -tetrachlorophenol 935 -95 -5 NS 0.002 -0.018 0.009 0.011 UKWIR, 1995 2,3,4- trichlorophenol 15950-66-0 AN 0.022 ± 0.0002 Wilson et al., 1997 2,3,4 - trichlorophenol 15950 -66 -0 AN 0 - 0.25 Wild et al., 1993
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Table A-2 (cont.) Concentrations reported for organic contaminants in sewage sludge in the UK. Compound CAS Sludge Range Mean Median Reference mg/kg dw μg/kg dw mg/kg dw μg/kg dw mg/kg dw μg/kg dw Chlorinated phenols (cont.) 2,3,4 - trichlorophenol 15950 -66 -0 NS 0.013 0.013 UKWIR, 1995 2,3,4 - trichlorophenol 15950 -66 -0 NS 0.03 - 1.06 Wild et al., 1993 2,3,6-trichlorophenol 933-75-5 AN 0.015 ± 0.0003 Wilson et al., 1997 2,3,6-trichlorophenol 933-75-5 NS 0.02 - 0.11 Wild et al., 1993 2,3,6-trichlorophenol 933-75-5 NS 0.002-0.005 0.003 0.003 UKWIR, 1995 2,4,5-trichlorophenol 95-95-4 AN 0.014 ± 0.0001 Wilson et al., 1997 2,4,5-trichlorophenol 95-95-4 NS 0.05 - 1.38 W ild et al., 1993 2,4,5 -trichlorophenol 95 -95 -4 NS 0.002 -0.067 0.026 0.023 UKWIR, 1995 2,4,6-trichlorophenol 88-06-2 AN 0.100 ± 0.002 Wilson et al., 1997 2,4,6-trichlorophenol 88-06-2 NS 0.16 - 5.06 W ild et al., 1993 2,4,6-trichlorophenol 88-06-2 NS 0.008-0.254 0.058 0.026 UKWIR, 1995 3,4,5-trichlorophenol 609-19-8 AN 0.028 ± 0.001 Wilson et al., 1997 3,4,5-trichlorophenol 609-19-8 NS 0.004-0.007 0.025 0.017 UKWIR, 1995 3,4,5-trichlorophenol 609-19-8 NS 0.07 - 1.52 Wild et al., 1993 pentachlorophenol 87 -86 -5 NS 0.005 -0.101 0.043 0.0305 UKWIR, 1995 pentachlorophenol 87 -86 -5 AN 0.1 - 2.04 Wild et al., 1993 Chlorobenzenes Chlorobenzene 108-90-7 NS 35100-192000 108875 101050 UKWIR, 1995 1,2-dichlorobenzene 95-50-1 NS nd-0.126 0.0174 0.0066 Wang et al., 1995 1,2-dichlorobenzene 95-50-1 NS 71.3-4110 877 237.5 UKWIR, 1995 1,2-dichlorobenzene 95-50-1 NS 1.5-13.6 7.5 8.5 UKWIR, 1995 1,3-dichlorobenzene 541-73-1 NS 13-467 110 47.2 UKWIR, 1995 1,3 -dichlorobenzene 541 -73 -1 NS 0.6 -40.2 5.3 2 UKWIR, 1995 1,3-dichlorobenzene 541-73-1 NS nd-0.101 0.0107 0.00296 Wang et al., 1995 0.00776- 1,4-dichlorobenzene 106-46-7 NS 0.0298 0.0255 Wang et al., 1995 0.00718 1,4 -dichlorobenzene 106 -46 -7 NS 561 -2320 1310 1250 UKWIR, 1995 1,4 -dichlorobenzene 106 -46 -7 NS 1.6 -33.9 14.3 12.65 UKWIR, 1995
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Table A-2 (cont.) Concentrations reported for organic contaminants in sewage sludge in the UK. Compound CAS Sludge Range Mean Median Reference mg/kg dw μg/kg dw mg/kg dw μg/kg dw mg/kg dw Chlorobenzenes (cont.) 1,3,5 -trichlorobenzene 108 -70 -3 NS nd -0.00391 0.00122 0.00081 Wang et al., 1995 1,3,5 -trichlorobenzene 108 -70 -3 NS 0.005 -39.7 0.06 UKWIR, 1995 1,3,5-trichlorobenzene 108-70-3 NS 0.11-0.65 0.34 0.27 UKWIR, 1995 1,2,4-trichlorobenzene 120-82-1 NS nd-0.0144 0.00263 0.00194 Wang et al., 1995 1,2,4-trichlorobenzene 120-82-1 NS 14.7-1070 264 51.1 UKWIR, 1995 1,2,4-trichlorobenzene 120-82-1 NS 0.02-4.8 0.92 0.36 UKWIR, 1995 1,2,3-trichlorobenzene 87-61-6 NS nd-0.00129 0.00021 nd Wang et al., 1995 1,2,3 -trichlorobenzene 87 -61 -6 NS 2.35 -484 107 9.11 UKWIR, 1995 1,2,3-trichlorobenzene 87-61-6 NS 0.04-1.23 0.31 0.16 UKWIR, 1995 1,2,4,5-tetrachlorobenzene 95-94-3 NS nd-0.00097 0.00033 0.00025 Wang et al., 1995 1,2,4,5-tetrachlorobenzene 95-94-3 NS 2.19-38.2 11.4 5.76 UKWIR, 1995 1,2,3,4-tetrachlorobenzene 12408-10-5 NS nd-0.00728 0.00189 0.00026 Wang et al., 1995 1,2,3,4-tetrachlorobenzene 12408-10-5 NS 0.22-45.4 11 4.41 UKWIR, 1995 1,2,3,4-tetrachlorobenzene 12408-10-5 NS 0.01-0.22 0.13 0.13 UKWIR, 1995 1,2,3,5 -tetrachlorobenzene 634 -90 -2 NS 0.43 -101 13 2.48 UKWIR, 1995 (1,2,3,5 + 1,2,4,5) - NS 0.01-0.21 0.11 0.1 UKWIR, 1995 tetrachlorobenzene 0.00010- pentachlorobenzene 608-93-5 NS 0.00069 0.00039 Wang et al., 1995 0.00283 pentachlorobenzene 608-93-5 NS 2.16-37.36 9.8 4.85 UKWIR, 1995 0.00074- hexachlorobenzene 118-74-1 NS 0.00251 0.00253 Wang et al., 1995 0.00550 hexachlorobenzene 118 -74 -1 NS 8.03 -90.1 26.1 17.2 UKWIR, 1995 hexachlorobenzene 118-74-1 NS 0.017 UKWIR, 199 5 0.0001- hexachlorobenzene 118-74-1 NS 0.013 0.002 UKWIR, 1995 0.055 hexachlorobenzene 118 -74 -1 NS 0.0002 -0.32 0.023 0.009 UKWIR, 1995 hexachlorobenzene 118-74-1 NS 0.01-0.09 0.09 0.09 UKWIR, 1995 sum of chlorobenzenes 0.0109- NS 0.0674 0.0389 Wang et al., 1995 (10 compounds) 0.327 Sum of chlorobenzenes NS <0.01-40.2 Rogers et al., 1989 (11 compounds)
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Table A-2 (cont.) Concentrations reported for organic contaminants in sewage sludge in the UK. Range Mean Median Reference Compound CAS Sludge mg/kg dw μg/kg dw mg/kg dw μg/kg dw mg/kg dw μg/kg dw Halogenated aliphatics (short chain) Chloroform 67 -66 -3 NS <0.1 -2.2 Wild and Jones, 1992 1,1 -Dichloroethane 75 -34 -3 NS 1.92 -16.6 7.97 7.11 UKWIR, 1995 Methylchloride 74-87-3 NS 0.06-30 Wild and Jon es, 1992 Trichloroethane 71-55-6 NS 0.011-0.119 0.038 0.029 UKWIR, 1995 2.00E-05-8.00E- Trichloroethane 71-55-6 NS 4.00E-04 0.7 UKWIR, 1995 04 Trichloroethane 71-55-6 NS 1.00E-04-0.028 0.007 0.006 UKWIR, 1995 Trichloroethane 71-55-6 NS 0.003 UKWIR, 1995 Tetrachloroethane 25322-20-7 NS <0.1-5.0 Wild and Jones, 1992 Tetrachloroethane 25322-20-7 NS 0.027-0.084 0.012 0.032 UKWIR, 1995 Tetrachloroethene 127-18-4 NS 0.004-0.515 0.093 0.047 UKWIR, 1995 Tetrachloromethane 56 -23 -5 NS <0.1 -0.2 Wild and Jones, 1992 Tetrachloromethane 56 -23 -5 NS 0.003 -0.1 0.019 0.007 UKWIR, 1995 Halogenated aliphatics (short DS 1.8-93.1 Nicholls et al., 2000 and medium chain) Monocyclic hydrocarbons and heterocycles Benzene 71 -43 -2 NS 0.084 -0.317 Bowen et al., 2003 Benzene 71 -43 -2 NS 0.0046 -0.483 Bowen et al., 2003 Benzene 71 -43 -2 NS 0.11 -0.317 0.084 0.211 UKWIR, 1995 m, p- Xylene 1330-20-7 AN 6.300 ± 0.910 Wilson et al., 1997 m, p- Xylene 1330-20-7 NS 0.276-22.1 5.05 3.79 U KWIR, 1995 o-Xylene 95-47-6 NS 0.22-7.18 1.73 1.46 UKWIR, 1 995 Toluene 108-88-3 NS nd-0.137 Wild and Jones, 1 992 Non-halogenated aliphatics n-alkanes (C17 -C32) NS 265 UKWIR, 1995 n-alkanes (C12-C25), pristine NS 540 UKWIR, 1995 and phytane Organotins Sum of organotins NS 0.01 -1.3 0.36 0.2 UKWIR, 1995 Pesticides Aldrin 309-00-2 AS 0.01 - 0.04 McIntyre and Le ster, 1984 Aldrin 309 -00 -2 PT 0.01 - 0.02 McIntyre and Lester, 1984
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Table A-2 (cont.) Concentrations reported for organic contaminants in sewage sludge in the UK. Range Mean Median Reference Compound CAS Sludge mg/kg dw μg/kg dw mg/kg dw μg/kg dw mg/kg dw μg/kg dw Pesticides (cont.) Chlordane 57 -74 -9 DS nd Stevens et al., 2003 DDT 50 -29 -3 DS nd Stevens et al., 2003 dieldrin 60-57-1 NS 0.01-53 Wild and Jones, 19 92 dieldrin 60-57-1 NS ND - 1.26 McIntyre and Les ter, 1982 endosulfan 115-29-7 DS nd Stevens et al., 2003 endrin 72-20-8 AS ND - 0.02 McIntyre and Leste r, 1984 endrin 72-20-8 PT 0.01 - 0.19 McIntyre and Les ter, 1984 endrin 72 -20 -8 AS 0.01 - 1.17 McIntyre and Lester, 1984 Hexachlorobenzene 118-74-1 DS 0.0064-0.260 0.042 0.022 Stevens et al., 2003 o,p-DDD 53-19-0 DS nd Stevens et al., 2003 o,p-DDE 3424-82-6 DS nd Stevens et al., 2003 p,p'-DDD 72-54-8 DS nd Stevens et al., 2003 p,p'-DDE 72-55-9 DS 0.006-0.028 0.013 0.013 Stev ens et al., 2003 p,p'-DDE 72-55-9 NS 0.01 - 0.49 McIntyre and L ester, 1982 Permethri n 52645 -53 -1 NS <0.01 -40.8 Rogers et al., 1989 α-hexachlorocyclohexane 319 -84 -6 DS nd Stevens et al., 2003 β-hexachlorocyclohexane 319 -85 -7 DS nd Stevens et al., 2003 γ -hexachlorocyclohexane 58-89-9 DS nd Stevens et al., 2003 γ -hexachlorocyclohexane 58-89-9 NS <0.01-70 W ild and Jones, 1992 γ -hexachlorocyclohexane 58-89-9 NS ND - 0.93 McIntyre and Lester, 1982 γ -hexachlorocyclohexane 58-89-9 AS 0.01 - 0.21 McIntyre and Lester, 1984 γ -hexachlorocyclohexane 58-89-9 PT 0.02 - 0.61 McIntyre and Lester, 1984 γ -hexachlorocyclohexane 58 -89 -9 AS 0.01 - 0.23 McIntyre and Lester, 1984 Phthalate acid esters/Plasticizers Di-n-butylphthalate 84-74-2 0.2-430 Wild and Jone s, 1992 Di-n-octylphthalate 117-84-0 trace-115 Wild and J ones, 1992 Polynuclear aromatic hydrocarbons (PAH) 1-Methylnaphthalene 90-12-0 DS 2.4-39 9.9 5 Stev ens et al., 2003 1-Methylphenanthrene 832-69-9 DS 0.46-8.1 3.9 3.5 Stevens et al., 2003 2,3,6 -trimethyl naphthalene 829 -26 -5 DS 0.96 -15 6.9 5.7 Stevens et al., 2003 2,6 -dimethyl naphthalene 581 -42 -0 DS 5.0 -110 30 18 Stevens et al., 2003 2-methyl naphthalene 91 -57 -6 DS 5.9 -93 24 13 Stevens et al., 2003
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Table A-2 (cont.) Concentrations reported for organic contaminants in sewage sludge in the UK. Compound CAS Sludge Range Mean Median Reference mg/kg dw μg/kg dw mg/kg dw μg/kg dw mg/kg dw μg/kg dw Polynuclear aromatic hydrocarbons (PAH)(cont.) acenaphthene 83-32-9 DS 1.7-6.6 4 3.9 Stevens et al., 2003 acenaphthene 83-32-9 D 0.9-2.1 1.45 1.46 UKWIR, 1995 acenapht hene 83 -32 -9 IMAN <0.3 -6.3 2.2 1.3 UKWIR, 1995 acenaphthylene 208 -96 -8 DS 0.030 -0.10 0.060 0.050 Stevens et al., 2003 acenaphthylene 208 -96 -8 D <0.38 -1 0.450 0.300 UKWIR, 1995 acenaphthylene 208 -96 -8 I <0.38 -7.83 8.900 7.800 UKWIR, 1995 anthracene 120-12-7 DS 0.38-1.8 0.72 0.65 Steven s et al., 2003 anthracene 120-12-7 NS 0.003-1.71 0.23 Bowen et al., 2003 anthracene 120-12-7 D <0.3-1.25 0.8 0.8 UKWIR, 1 995 anthracene 120-12-7 I <0.3-10.6 3.7 3.02 UKWIR, 1995 benzo[a]anthracene 56 -55 -3 DS 0.6 -2.8 1.8 1.8 Stevens et al., 2003 benzo[a]pyrene 50-32-8 DS 0.69-4.0 2.1 2.1 Steve ns et al., 2003 Benzo[b]fluoranthene 205-99-2 NS 2.1-14.8 Wild and Jones, 1992 benzo[b]fluoranthene 205-99-2 DS 1.1-7.2 3 2.9 S tevens et al., 2003 benzo[e]pyrene 192-97-2 DS 0.82-4.4 2.2 2 Steven s et al., 2003 benzo[ghi]perylene 191-24-2 DS 0.47-2.3 1.3 1.1 Stevens et al., 2003 Benzo[ghi]perylene 191-24-2 NS nd-0.3 Wild an d Jones, 1992 benzo[j+k]fluoranthene DS 0.7 -4.5 2.2 1.9 Stevens et al., 2003 bipheny l 92 -52 -4 DS 1.7 -28 6.3 4 Stevens et al., 2003 chrysene 218 -01 -9 DS 1.0 -6.0 2.6 2.3 Stevens et al., 2003 chrysene 218 -01 -9 D <0.3 -1.5 0.34 <0.3 UKWIR, 1995 chrysene 218-01-9 IMAN <0.3-1.18 0.6 0.79 UKWIR, 1995 dibenz[ah]anthracene 53-70-3 DS 0.060-0.38 0.19 0.19 Stevens et al., 2003 Fluoranthene 206-44-0 NS 2.2-28.5 Wild and Jon es, 1992 Fluoranthene 206-44-0 NS 1.1-4 2.3 Bowen et al. , 2003 Fluoranthene 206 -44 -0 NS 1.04 Bowen et al., 2003 Fluoranthene 206 -44 -0 D 1.1 -4 2. 3 2.5 UKWIR, 1995 Fluoranthene 206-44-0 I 0.3-7.2 4.5 5.6 UKWIR, 1 995 Fluoranthene 206-44-0 NS 0.34-11.4 2.06 UKWIR, 1995 fluoranthene 206-44-0 DS 1.4-7.4 4.9 5.4 Stevens et al., 2003 fluorene 86-73-7 DS 3.6-8.1 5.7 5.7 Stevens et a l., 2003 fluorene 86-73-7 D 1.26-2.54 1.95 1.81 UKWIR, 19 95 fluorene 86 -73 -7 I 3.4 -15.8 6.1 5.85 UKWIR, 1995
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Table A-2 (cont.) Concentrations reported for organic contaminants in sewage sludge in the UK. Compound CAS Sludge Range Mean Median Reference mg/kg dw μg/kg dw mg/kg dw μg/kg dw mg/kg dw μg/kg dw Polynuclear aromatic hydrocarbons (PAH) (cont.) indeno[1,2,3- 193-39-5 DS 0.39-2.7 1.1 1.1 Stevens et al., 2003 cd]pyrene Naphthalene 91 -20 -3 DS 0.15 -19 3.7 1.4 Stevens et al., 2003 Naphthalene 91-20-3 NS 0.8-3 1.8 1.9 UKWIR, 1995 Naphthalene 91-20-3 IMAN 0.5-14.9 7.4 5.9 UKWIR, 1995 Naphthalene 91-20-3 NS nd-5.8 Wild and Jones, 1992 Perylene 198-55-0 DS 0.12-0.61 0.36 0.35 Stevens et al., 2003 Phenanthrene 85 -01 -8 NS 2.1 -8.3 Wild and Jones, 1992 Phenanthrene 85 -01 -8 D 2.4 -6.1 3.9 3.3 UKWIR, 1995 Phenanthrene 85 -01 -8 I <0.3 -32.4 10.6 6.47 UKWIR, 1995 Phenanthrene 85-01-8 DS 3.2-16 7 6.4 Stevens et al., 2003 Pyrene 129-00-0 NS 1.2-36.8 Wild and Jones, 19 92 Pyrene 129-00-0 DS 2.1-5.6 4.2 4.5 Stevens et al ., 2003 Pyrene 129-00-0 D 0.8-2.15 1.5 1.66 UKWIR, 1995 Pyrene 129-00-0 I <0.3-7.1 3.4 3.5 UKWIR, 1995 PAHs NS 1 to 10 Wild et al., 1992 PAHs NS 67-246 Leschber, 2006 PAHs NS 18 -46 34 Leschber, 2006 PAH (sum of 16 DS 18-50 36 34 Stevens et al., 2003 compounds) Polychlorinated byphenils (PCBs) arochlor 1016 12674 -11 -2 NS 0.20 -75 Wild and Jones, 1992 arochlor 1248 12672 -29 -6 NS nd Wild and Jones, 1992 arochlor 1260 11096-82-5 NS 0.02-0.46 Wild and Jones, 1992 6 25569-80-6 NS 0.008-0.7 0.019 UKWIR, 1995 8 34883-43-7 NS 0.002-0.021 0.009 UKWIR, 1995 18 37680-65-2 DS 1.5-1.4 5.7 5 Stevens et al., 2 003 18 37680 -65 -2 NS 0.001 -0.018 0.009 UKWIR, 1995 22 38444 -85 -8 DS 1.7 -43 9.3 6 Stevens et al., 2003 28 7012-37-5 DS 5.1-26 12 11 Stevens et al., 200 3 28 7012-37-5 NS 0.001-0.021 0.01 UKWIR, 1995 28 7012-37-5 NS 0.0005-1.626 0.142 0.007 UKWIR, 1995 31 16606-02-3 DS 3.5-56 13 8.1 Stevens et al., 2 003 44 41464-39-5 DS 1.0-6.5 3.1 2.8 Stevens et al., 2003
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Table A-2 (cont.) Concentrations reported for organic contaminants in sewage sludge in the UK. Compound CAS Sludge Range Mean Median Reference mg/kg dw μg/kg dw mg/kg dw μg/kg dw mg/kg dw μg/kg dw Polychlorinated byphenils (PCBs) (cont.) 41/64 DS 1.3-7.3 3.4 3.1 Stevens et al., 2003 49 41464-40-8 DS 1.7-13 4.6 3.8 Stevens et al., 2003 52 35693 -99 -3 DS 3.1 -28 12 8.7 Stevens et al., 2003 52 35693 -99 -3 NS 0.003 -0.041 0.011 UKWIR, 1995 54 15968 -05 -5 DS nd Stevens et al., 2003 61 33284 -53 -6 NS 0.001 -0.032 0.002 UKWIR, 1995 60/56 DS 0.4-4.8 1.8 1.9 Stevens et al., 2003 61/74 NS 0.0004-0.456 0.042 0.005 UKWIR, 1995 66 32598-10-0 NS 0.001-0.009 0.007 UKWIR, 1995 70 32598-11-1 DS 2.7-33 8.3 6.1 Stevens et al., 2003 74 32690 -93 -0 DS 1.7 -8.7 3.5 3 Stevens et al., 2003 77 32598-13-3 DS 0.540-4.270 Sewart et al., 19 95 77 32598-13-3 DS 0.238-54.500 Stevens et al., 2001 87 38380-02-8 DS 0.9-5.3 2.6 2.1 Stevens et al., 2003 82/151 NS 0.001-0.028 0.012 UKWIR, 1995 90/101 DS 3.8-74 13 8.2 Stevens et al., 2003 95 38380-02-8 DS 2.3-22 6.4 4.4 Stevens et al., 2003 99 38380 -01 -7 DS 1.1 -4.9 2.6 2.1 Stev ens et al., 2003 99 38380 -01 -7 NS 0.001 -0.02 0.006 UKWIR, 1995 101 37680 -73 -2 NS 0.001 -0.047 0.016 UKWIR, 1995 104 56558 -16 -8 DS nd Stevens et al., 2003 104 56558-16-8 NS 0.001-0.02 0.011 UKWIR, 1995 105 32598-14-4 DS nd Stevens et al., 2003 105 32598-14-4 NS 0.002-0.026 0.012 UKWIR, 1995 110 38380-03-9 DS 1.5-10 4.6 4 Stevens et al., 2 003 110 38380 -03 -9 MAN 0.001 -0.043 0.014 UKWIR, 1995 114 74472 -37 -0 DS nd Stevens et al., 2003 118 31508-00-6 DS 1.6-20 6.1 5.2 Stevens et al., 2003 118 31508-00-6 NS 0.0007-0.091 0.017 0.002 UKWIR, 1995 126 54765-28-8 DS nd-0.280 Sewart et al., 1995
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Table A-2 (cont.) Concentrations reported for organic contaminants in sewage sludge in the UK. Compound CAS Sludge Range Mean Median Reference mg/kg dw μg/kg dw mg/kg dw μg/kg dw mg/kg dw μg/kg dw Polychlorinated byphenils (PCBs ) (cont.) 126 54765-28-8 DS 0.0199-6.520 Stevens et al., 2001 123 65510 -44 -3 DS 0.3 -8.4 4 3.4 Stevens et al., 2003 132 38380-05-1 DS 10 to 39 20 19 Stevens et al., 2003 138 35065-28-2 DS 6.9-23 13 12 Stevens et al., 2 003 138 35065-28-2 NS 0.002-0.047 UKWIR, 1995 141 52712-04-6 DS 1.3-5.7 2.8 2.3 Stevens et al. , 2003 149 38380 -04 -0 DS 5.7 -20 11 8.9 Stevens et al., 2003 149 38380 -04 -0 NS 0.002 -0.065 0.019 UKWIR, 1995 151 52663 -63 -5 DS 2.1 -7.6 3.8 2.9 Stevens et al., 2003 153 35065-27-1 DS 7.3-27 14 13 Stevens et al., 2 003 153 35065-27-1 NS 0.001-0.049 0.012 UKWIR, 1995 155 33979-03-2 DS nd Stevens et al., 2003 156 38380-08-4 DS 0.5-2.1 1.1 0.97 Stevens et al., 2003 157 69782-90-7 DS 0.1-0.49 0.31 0.29 Stevens et al., 2003 158 74472 -42 -7 DS 0.2 -2.3 1.2 1 Stevens et al., 2003 167 52663-72-6 DS 0.2-1.1 0.49 0.4 Stevens et al., 2003 169 32774 -16 -6 DS nd -0.055 Sewart et al., 1995 169 32774-16-6 DS 0.0045-2.010 Stevens et al., 2001 170 32774-16-6 DS 1.3-8.6 3.3 2.3 Stevens et al. , 2003 170 32774-16-6 NS 0.001-0.061 0.021 UKWIR, 1995 174 35065-30-6 DS 1.6-9.7 3.9 2.9 Stevens et al. , 2003 180 38411 -25 -5 DS 4.7 -23 10 8.5 Stevens et al., 2003 180 38411 -25 -5 NS 0.002 -0.043 0.013 UKWIR, 1995 183 35065 -29 -3 DS 1.2 -5.7 2.6 2.1 Stevens et al., 2003 187 52663-76-0 DS 2.6-12 5.8 4.8 Stevens et al., 2003 187 52663-76-0 NS 0.001-0.018 0.005 UKWIR, 1995 187 52663-76-0 NS 0.001-0.018 0.005 UKWIR, 1995 188 52663-76-0 DS nd Stevens et al., 2003 189 52663-76-0 DS 0.010-0.35 0.17 0.17 Stevens et al., 2003 194 35694 -8-7 DS 0.1 -7.5 2.6 2 Stevens et al., 2003 199 52663-73-7 DS 0.090-1.3 0.35 0.26 Stevens et al., 2003
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Table A-2 (cont.) Concentrations reported for organic contaminants in sewage sludge in the UK. Compound CAS Sludge Range Mean Median Reference mg/kg dw μg/kg dw mg/kg dw μg/kg dw mg/kg dw μg/kg dw Polychlorinated byphenils (PCBs ) (cont.) 194/205 NS 0.002-0.035 0.01 UKWIR, 1995 201 40186 -71 -8 NS 0.001 -0.013 0.006 UKWIR, 1995 203 52663-76-0 DS 1.4-11 3.1 2.5 Stevens et al., 2003 206 40186-72-9 NS 0.001-0.02 0.008 UKWIR, 1995 208 52663-77-1 NS 0.001-0.021 0.006 UKWIR, 1995 PCB (sum) NS 0.05-0.5 Bowen et al., 2003 PCB (sum of 7 compounds) DS 44 -180 81 71 Stevens et al., 2003 three PCBs (non -ortho - DS 0.272-63 0.695 Stevens et al., 2001 substituted) Polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs) 0.00204- Monochlorodibenzodioxins DS Stevens et al., 2001 0.0548 Monochlorodibenzofurans DS 0.00797-1.410 Sew art et al., 1995 Dichlorodibenzodioxins DS 0.793-5.250 Steve ns et al., 2001 Dichlorodibenzofurans DS 3.250-414.00 Sewart et al., 1995 Trichlorodibenzodioxins DS 0.0114 -1.470 Stevens et al., 2001 Trichlorodibenzofurans DS 0.0262 -1.020 Stevens et al., 2001 Tetrachlorodibenzodioxins DS nd-0.190 Steven s et al., 2001 0.00335- Tetrachlorodibenzodioxins DS Sewart et al., 1995 0.0768 Tetrachlorodibenzofurans DS nd -0.430 Stevens et al., 2001 Tetrachlorodibenzofurans DS 0.0451 -0.180 Stevens et al., 2001 Pentachlorodibenzodioxins DS nd-0.480 Steven s et al., 2001 Pentachlorodibenzodioxins DS 0.0362 -0.308 Sewart et al., 1995 Pentachlorodibenzofurans DS nd-0.500 Stevens et al., 2001 Pentachlorodibenzofurans DS 0.0551-0.396 Sew art et al., 1995 Hexachlorodibenzodioxins DS 0.040-1.660 Stev ens et al., 2001 Hexachlorodibenzodioxins DS 0.0890-274.0 Sew art et al., 1995 Hexachlorodibenzofurans DS nd -0.800 Stevens et al., 2001 Hexachlorodibenzofurans DS 0.0876 -1.120 Stevens et al., 2001
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Table A-2 (cont.). Concentrations reported for organic contaminants in sewage sludge in the UK. Compound CAS Sludge Range Mean Median Reference mg/kg dw μg/kg dw mg/kg dw μg/kg dw mg/kg dw μg/kg dw Polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs) (cont.) Heptachlorodibenzodioxins DS 0.380-150.00 St evens et al., 2001 Heptachlorodibenzodioxins DS 0.423-22.50 Sew art et al., 1995 Heptachlorodibenzofurans DS 0.155 -3.090 Stevens et al., 2001 Heptachlorodibenzofurans DS 0.167 -4.150 Sewart et al., 1995 Octachlorodibenzodioxins DS 0.460 -59.00 Stevens et al., 2001 Octachlorodibenzodioxins DS 2.320 -51.50 Sewart et al., 1995 Octachlorodibenzofuran DS 0.020-1.980 Steven s et al., 2001 Octachlorodibenzofuran DS 0.192-2.591 Sewart et al., 1995
Total C 14 -C18 DD/Fs DS 4.030-85.30 15.2 6.53 Stevens et al. , 2001 Total C 11 -C18 DD/Fs DS 8.880-428.00 75.3 23.3 Stevens et al. , 2001 Polychlorinated naphthal enes (PCNs) 19 DS nd-1.8 0.5 0.2 Stevens et al., 2003 23 DS nd-20 10 9.7 Stevens et al., 2003 15 DS 12 to 78 27 23 Stevens et al., 2003 16 DS 13-97 31 26 Stevens et al., 2003 42 DS 0.3-0.8 0.5 0.5 Stevens et al., 2003 PCN 4-11* DS nd-0.4 0.2 0.2 Stevens et al., 200 3 38(40) DS 1.5 -3.9 2.4 2.2 Stevens et al., 2003 46 DS nd -1.5 0.9 0.9 Stevens et al., 2003 33/34/37 DS 1.9 -4.4 3 2.9 Stevens et al., 2003 47 DS 0.6 -3.2 1.1 0.9 Stevens et al., 2003 36/35 DS 0.2-1.1 0.6 0.6 Stevens et al., 2003 52/60 DS nd-0.9 0.3 0.3 Stevens et al., 2003 59 DS nd-1.9 0.4 nd Stevens et al., 2003 19 DS nd-1.8 0.5 0.2 Stevens et al., 2003 23 DS nd -20 10 9.7 Stevens et al., 2003 15 DS 12 to 78 27 23 Stevens et al., 2003 16 DS 13-97 31 26 Stevens et al., 2003 42 DS 0.3-0.8 0.5 0.5 Stevens et al., 2003 PCN 4-11* DS nd-0.4 0.2 0.2 Stevens et al., 200 3 38(40) DS 1.5-3.9 2.4 2.2 Stevens et al., 2003 46 DS nd-1.5 0.9 0.9 Stevens et al., 2003
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Table A-2 (cont.) Concentrations reported for organic contaminants in sewage sludge in the UK. Compound CAS Sludge Range Mean Median Reference mg/kg dw μg/kg dw mg/kg dw μg/kg dw mg/kg dw μg/kg dw Polychlorinated naphthalenes (PCNs) (cont.) 33/34/37 DS 1.9-4.4 3 2.9 Stevens et al., 2003 47 DS 0.6-3.2 1.1 0.9 Stevens et al., 2003 36/35 DS 0.2 -1.1 0.6 0.6 Stevens et al., 2003 52/60 DS nd -0.9 0.3 0.3 Stevens et al., 2003 59 DS nd -1.9 0.4 nd Stevens et al., 2003 Surfactants LAS AN 9300-18800 Jones and Northcott, 2000 LAS NS 800-14300 Wild and Jones, 1992 Nonylphenol NS 450-25300 Wild and Jones, 1992 Synthetic musks Amberette 83 -66 -9 DS nd Stevens et al., 2003 Cashmeran 33704-61-9 DS nd Stevens et al., 200 3 Celestolide (ADBI) 13171-00-1 DS 0.010-0.26 0.071 0.035 Stevens et al., 2003 Galaxolide (HHCB) 1222-05-5 DS 1.9-81 27 26 Stev ens et al., 2003 Musk moskene 116-66-5 DS nd Stevens et al., 20 03 Musk ketone 81-14-1 DS nd Stevens et al., 2003 Musk xylene 81-15-2 DS nd Stevens et al., 2003 Phantolide (AHMI) 15323 -35 -0 DS 0.032 -1.1 0.41 0.39 Stevens et al., 2003 Musk tibetene 145 -39 -1 DS nd Stevens et al., 2003 Tonalide (AHTN) 1506 -02 -1 DS 0.12 -16 4.7 4 Stevens et al., 2003 Traseolide (ATII) 68140 -48 -7 DS 0.044 -1.1 0.45 0.45 Stevens et al., 2003
EDTA- ethylenediaminetetraacetic acid; NS- not specified; DS-digested sludge; AN- anaerobically digested; I- industrial; D- domestic; IMAN- industrial mesophilic anaerobically digested; MAN- mesophilic anaerobically digested.
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APPENDIX C
ANNEX I CATEGORIES OF WASTE
Q1 Production or consumption residues not otherwise specified below Q2 Off-specification products Q3 Products whose date for appropriate use has expired Q4 Materials spilled, lost or having undergone other mishap, including any materials, equipment, etc., contaminated as a result of the mishap Q5 Materials contaminated or soiled as a result of planned actions (e.g. residues from cleaning operations, packing materials, containers, etc.) Q6 Unusable parts (e.g. reject batteries, exhausted catalysts, etc.) Q7 Substances which no longer perform satisfactorily (e.g. contaminated acids, contaminated solvents, exhausted tempering salts, etc.) Q8 Residues of industrial processes (e.g. slags, still bottoms, etc.) Q9 Residues from pollution abatement processes (e.g. scrubber sludges, baghouse dusts, spent filters, etc.) Q10 Machining/finishing residues (e.g. lathe turnings, mill scales, etc.) Q11 Residues from raw materials extraction and processing (e.g. mining residues, oil field slops, etc.) Q12 Adulterated materials (e.g. oils contaminated with PCBs, etc.) Q13 Any materials, substances or products the use of which has been banned by law Q14 Products for which the holder has no further use (e.g. agricultural, household, office, commercial and shop discards, etc.) Q15 Contaminated materials, substances or products resulting from remedial action with respect to land Q16 Any materials, substances or products which are not contained in the abovementioned categories.
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APPENDIX D
Table A - 3 Plant toxins that may occur in green compost Potenti ally hazardous agents – Plant Toxins
Volatile oils : (mustard oil, horseradish, wild radish) 1. n-propyl disulphate (Wild Garlic, Allium ursinum , & other onions) 2. Mercurialine (Dog’s Mercury, Mercurialis perennis ; Annual Mercury, Mercurialis annua ) 3. Tetrahydrocannabinols (Cannabis, Cannabis sativa ) 4. Protoanemonin (Wood Anemone, Anemone nemerosa ; Buttercup, Ranunculus spp.) Tannins: Tannic acid (Oak, Quercus spp.; Bracken, Pteridium aquilinum ; broomrape)
Alkaloids: 1. Aconitine (Monkshood/Wolf’s-bane, Aconitum napellus ) 2. Ajacine/Ajaconiine (all delphiniums) 3. Aquaticine ( Senecio aquaticus ) 4. Atropine, hyoscyamine, hyoscine (Deadly Nightshade, Atropa belladonna ; Henbane, Hyoscyamus niger; Thorn-apple, Datura stramonium ) 5. Berberine (Barberry, Berberis spp.) 6. Bryonicine (White Bryony, Bryonia dioica ) 7. Buxine (Box, Buxus sempervirens ) 8. Chelidonine/homochelidonine/chelerythrine/sanguinarine (Celandines, Chelidonium majus ; horned or sea poppy) 9. Colchicine, colchiceine (Meadow Saffron, Colchicum autumnale ) 10. Coniine, methylconiine, coniceine, conhydrine (Hemlock, Conium maculatum ; fool’s parsley) 11. Cynapine (Fool’s parsley) 12. Cytisine (Laburnum, Laburnum anagyroides; broom) 13. Ephedrine (Monkswood, Aconitum napellus ; Yew, Taxus baccata ) 14. Imperialine (fritillary) 15. Isatadine ( Senecio isatadeus ) 16. Jacobine, jacodine, jaconiine (all Ragwort, Senecio spp.) 17. Lobeline (lobelias) 18. Lupinine, lupinidine, l-lupanine, dl -lupanine, hydroxylupanine (Lupins, Lupinus spp.) 19. Lycorine, galanthamine (Daffodil, Narcissus spp.) 20. d-lysergic acid amide or ergine (Morning Glory, Ipomoea spp.) 21. Morphine (Opium Poppy, Papaver somniferum ) 22. Nicotine (tobacco inc. ornamental varieties) 23. Palustrine (Horsetails, Equisetum spp.) 24. Rhoeadine (Field Poppy, Papaver rhoeas ) 25. Solanine, solanein, solanidine (Woody Nightshade, Solanum dulcamara; Black/Garden Nightshade, Solanum nigrum ; Potato foliage & green potato, Solanum tuberosum ; tomato foliage) 26. Solanocapsine (Christmas Cherry, Solanum capsicastrum and Solanum pseudocapsicum ) 27. Sparteine (broom) 28. Taxine (Yew, Taxus baccata ) 29. Temuline (darnel)
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Table A - 3 (cont.) Plant toxins that may occur in green compost Glycosides: 1. Aesculin (Horse Chestnut, Aesculus hippocastanum ; Ash, Fraxinus excelsior ) 2. Amygdalin, glycoside + emulsion, enzyme = hydrocyanic acid (kernals of apple, pear, plum, cherry, peach, apricot, almond & leaves of Cherry Laurel, Prunus laurocerasus ) 3. Bryonin (White Bryony, Bryonia dioica ) 4. Convallotoxin, Convallamarin, convallarin convalloside (Lilly of the valley, Convallaria majalis ) 5. Cyanogenetic glycosides (Marsh & Sea arrow grass) 6. Cyclamin (Cyclamins) 7. Digitoxin, digitalin (Foxglove, Digitalis purpurea ; water figwort) 8. Emodin (Buckthorn, Rhamnus cathartica ; Alder) 9. Euonymine (Spindle Tree, Euonymus europaeus ) 10. Helleborein/Helleborin (Hellebores, Veratrum spp.) 11. Ilicin (Holly, Ilex aquifolium ) 12. Iridin/Irisin (Irises, Iris spp.) 13. Linamarin (glycoside and goitrogen) 14. Ligustrin (Privet, Ligustrum spp.) 15. Lotaustralin (white clover) 16. Narthecin (Bog Asphodel, Narthecium ossifragum ) 17. Paridin (herb paris) 18. Phytolaccin, phytolaccatoxin (Pokeweed, Phytolacca Americana ) 19. Prunasin (Bracken, Pteridium aquilinum ; Cherry Laurel, Prunus laurocerasus ) 20. Ranunculin (Wood Anemone, Anemone nemorosa ; Traveller’s Joy, Clematis vitalba ; Buttercup, Ranunculus spp.) 21. Saponin(s) (chickweed; corn cockle; pinks & carnations; fat hen, Chenopodium album ; nightshade; herb paris; Ivy, Hedera helix ; Dog’s Mercury, Mercurialis perennis ; Annual Mercury, Mercurialis annua ; Lily of the Valley, Convallaria majalis ; Bog Asphodel, Narthecium ossifragum ; Solomon’s Seal, Polygonatum multiflorum) 22. Scillarens (Bluebell, Hyacinthoides non-scripta ) 23. Scoparin (broom) 24. Scillaine (Daffodil, Narcissus spp.) 25. Similacin (Scarlet pimpernel) 26. Sinigrin (Horse Radish, Armoracia rusticana ) Phyto -dynamic substances : (buckwheat; St. John’s wort; Bog Asphodel, Nart hecium ossifragum ; yellow trefoils)
1. Furocoumarins (Giant Hogweed, Haracleum mantegazzianum ) 2. Hypericin (St. John’s Wort, Hypericum perforatum ) Proteins, peptides & amino acids 1. Ricin (Caster Oil Plant, Ricinus communis ) 2. Viscotoxin A & B (Mistletoe, Viscum album )
Enzymes: 1. linamarase (Flax) 2. Thiaminase (destroys vit B1; Horsetails, Equisetum spp.; Bracken, Pteridium aquilinum )
Carcinogens: 1. Ptaquiloside (Bracken, Pteridium aquilinum )
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Table A - 3 (cont.) Plant toxins that may occur in green compost Oxali c acid and soluble oxalates: (fodder beets & mangles; wood sorrels; Docks & sorrels; rhubarb; water pepper; knotweed; peachwort) 1. Ca Oxylate crystals (Cuckoo Pint, Arum maculatum ; Black Bryony, Tamus communis ) 2. Ca Oxylate sap (Dumb Cane, Dieffenbachia spp.; Cheese Plant, Monstera deliciosa ; Elephant’s Ear, Philodendron spp.; Arum Lily, Zantedeschia spp.) 3. Oxalates (Fat Hen, Chenopodium album ; Rhubarb, Rheum rhaponticum ) Others/not able to group: 1. Hydrocyanic acid (apricot, cherry, peach & plum kernels; apple & pear pips; cherry laurel; linseed; millet; sorghums; wild white clover; juncus; yew) 2. Thiouracil, and other goitrogens (cabbages, esp. kale) 3. Aflatoxin 4. Molybdenum, ‘teart pastures’ 5. Potassium nitrate/nitrites (taken up by fodder crops inc. oats, beet, turnips, kale, rape) 6. Dicoumarol (from breakdown of coumarin in damaged clover) 7. Mezerein, daphnetoxin (Mezereon, Daphne mezereum ; Spurge Laurel, Daphne laureola ) 8. Cicutoxin (Cowbane, Cicuta virosa ) 9. Oenathotoxin (Hemlock Water Dropwort, Oenanthe crocata ) 10. Euphorbiosteroid (Spurges inc. dog’s mercury & annual mercury) 11. Diterpene esters (Sun and Petty Spurge, Euphorbia helioscopia and Euphorbia peplus ; Poinsettia, Euphorbia pulcherrima ) 12. Lantadene A (Lantana, Lantana spp.) 13. Andromedotoxin or acetylandromedol (Rhododendrons, azaleas & kalmias; Pieris, Pieris spp.) 14. Fagin, Beech, Fagus sylvatica Limited info: 1. Glycoside, Oleander, Nerium oleander 2. Alkaloids, Comfrey, Symphytum officinale 3. Cyanide-producing glycoside, Elder, Sambucus spp. 4. Snowberry, Symphoricarpos rivularis 5. Cypress, Cupressus spp.
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APPENDIX E
Table A-4 Concentration ranges of compounds detected in bed sediments Compound Mean (min; max) Country Reference μg/kg DW Brominated flame retardants 2,2’,4,4’ -TeBDE 45.06 (<0.3; 368) UK Allchin et al., 1999 2,2’,4,4’,5 -PeBDE 86.39 (<0.6; 898) UK Allchin et al., 1999 2,2’,3,4,4’ -PeBDE 9.36 (<0.4; 72) UK Allchin et al., 1999 Tetra+Penta -BDEs 40 (21; 59) Japan Eljarrat and Barcelo, 2003 BDE -47 Maximum - 490 Sw eden Eljarrat and Barcelo, 2003 BDE -47 3.2 (<0.17; 6.2) Europe Eljarrat and Barcelo, 2003 BDE -99 Maximum - 750 Sweden Eljarrat and Barcelo, 2003 BDE -99 3.6 (<0.19; 7) Europe Eljarrat and Barcelo, 2003 BDE -100 Maximum - 170 Sweden Eljarrat and Barcelo, 2003 BDE -47+99+100 Maximum – 9.6 Sweden Eljarrat and Barcelo, 2003 BDE -209 Maximum - 360 Sweden Eljarrat and Barcelo, 2003 Pesticides Sum of DDT Median – 17 USA (all lakes) Metre and and Mahler, 2005 Sum of DDT Median - 29 USA (dense urban lake) Metre and and Mahler, 2005 Sum of DDT Median - 9 USA (light urban lake) Metre and and Mahler, 2005 Sum of DDT Median - 4 USA (reference lake) Metre and and Mahler, 2005 Atrazine 30 (1; 166) England Long et al., 1998 Carbaryl 119 (21; 333) England Long et al., 1998 Carbaryl 0.5 (<0.5; 15) England (urban) Daniels et al., 2000 Carbaryl 0.6 (<0.5; 10) England (rural) Daniels et al., 2000 Cis -Permethrin 1392 (3; 5 451) England Long et al., 1998 Cyanazine 53 (1; 146) England Long et al., 1998 Cypermethrin 743(4 ; 1 140) England Long et al., 1998
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Table A-4 (cont.) Concentration ranges of compounds detected in bed sediments Compound Mean (min; max) Country Reference μg/kg DW Pesticides (cont.) Deltamethrin nd England Long et al., 1998 Desmetryn 56 (2; 311) England Long et al., 1998 Diazinon 1936 (30; 11 658) England Long et al., 1998 Dimethoate 67 (5; 310) England Long et al., 1998 Fenitrothio n 17 (1; 114) England Long et al., 1998 Fenpropimorph 5 (<0.5; 197) England (urban) Daniels et al., 2000 Fenpropimorph 3 (<0.5; 92) England (rural) Daniels et al., 2000 Fenvalerate 332 (11; 336) England Long et al., 1998 Flutriafol 4 England Long et al., 1998 Lindane 141 (6; 487) England Long et al., 1998 Linuron 51 England Long et al., 1998 Linuron 11 (<0.5; 132) England (urban) Daniels et al., 2000 Linuron 11 (<0.5; 53) England (rural) Daniels et al., 2000 Malathion 52 (1; 305) England Long et al ., 1998 Parathion 78 (1; 613) England Long et al., 1998 Prometryn 295 (2; 3 050) England Long et al., 1998 Prometryn 1 (<0.5; 8) England (urban) Daniels et al., 2000 Prometryn 2 (<0.5; 7) England (rural) Daniels et al., 2000 Propanil 46 (3; 161) England Long et al., 1998 Propazine 3002 (1; 3 020) England Long et al., 1998 Propiconazol 48 (21; 96) England Long et al., 1998 Simazine 58 (1; 539) England Long et al., 1998 Terbutryn 26 (1; 94) England Long et al., 1998 Trans -Permethrin 189 (3; 567) England Long et al., 1998
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Table A–4 (cont.) Concentration ranges of compounds detected in bed sediments Compound Mean (min; max) Country Reference μg/kg DW Pesticides (cont.) Trifluralin 3 (1; 8) England Long et al., 1998 α-BHC 45 (8; 164) England Lo ng et al., 1998 Pharmaceuticals Diclofenac nd Switzerland Buser et al ., 1998b 17 α - Ethinylestradiol (<0.05 ; 0.5) Australia Braga et al., 2005 17 α - Ethinylestradiol (< 0.4 ; 0.9) Germany Ternes et al., 2006 17 α - Ethinylestradiol (nd; 22.8) Spain Ló pez de Alda et al., 2002 17 β - Estradiol (0.22; 2.48) Australia Braga et al., 2005 17 β - Estradiol (<0.2; 1.5) Germany Ternes et al., 2006 Diethylstilbestrol nd Spain López de Alda et al., 2002 Estradiol nd Spain López de Alda et al., 2002 Estriol (nd ; 3.37) Spain López de Alda et al., 2002 Estrone (nd; 11.9) Spain López de Alda et al., 2002 Estrone (0.16; 1.17) Australia Braga et al., 2005 Estrone (<0.2; 2) Germany Ternes et al., 2006 Diphenhydramine (<5; 48.6) USA Ferrer et al., 2004 Phenols 23. 4 (2.1; 292) UK Davis and Rudd, 1999 Phtalates DEHP 7871 (229; 19 421) England Long et al., 1998 Polynuclear aromatic hydrocarbons (PAH) Sum of PAHs 16 (0; 203) UK Davis and Rudd, 1999 Sum of 13 PAHs Median – 3400 USA (all lakes) Metre and and Mahle r, 2005 Sum of 13 PAHs Median - 8900 USA (dense urban lake) Metre and and Mahler, 2005 Sum of 13 PAHs Median - 1300 USA (light urban lake) Metre and and Mahler, 2005
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Table A–4 (cont.) Concentration ranges of compounds detected in bed sediments Compou nd Mean (min; max) Country Reference μg/kg DW Polynuclear aromatic hydrocarbons (PAH)(cont.) Sum of 13 PAHs Median - 320 USA (reference lake) Metre and and Mahler, 2005 Fluoranthene 2576 (36; 15 307) England Long et al., 1998 Fluoranthene 27 (<0.5; 702) England (urban) Daniels et al., 2000 Fluoranthene 40 (<0.5; 369) England (rural) Daniels et al., 2000 Naphthalene 452 (22; 2 717) England Long et al., 1998 Naphthalene 9 (2; 39) England (urban) Daniels et al., 2000 Naphthalene 16 (5; 39) England (rural) Daniels et al., 2000 Pyrene 2226 (32; 11 854) England Long et al., 1998 Pyrene 30 (<0.5; 729) England (urban) Daniels et al., 2000 Pyrene 65 (1; 533) England (rural) Daniels et al., 2000 Polychlorinated Biphenils (PCBs) Sum of PCBs Median – 43 USA (all lakes) Metre and and Mahler, 2005 Sum of PCBs Median - 108 USA (dense urban Metre and and Mahler, 2005 lake) Sum of PCBs Median - 15 USA (light urban lake) Metre and and Mahler, 2005 Sum of PCBs Median - nd USA (reference lake) Metre and and Mahler, 2005 Surfactant England Long et al., 1998 Nonylphenol 30 (6; 69) England Long et al., 1998 Nonylphenol 2 (<0.5; 23) England (urban) Daniels et al., 2000 Nonylphenol 5 (<0.5; 15) England (rural) Daniels et al., 2000 Nonylphenol Maximum - 2.83 mg/kg Austria Micić and Hofmann, 2009 Nonylphenol monoethoxylate Maximum – 2.10 mg/kg Austria Micić and Hofmann, 2009 Nonylphenol diethoxylate Maximum – 0.28 mg/kg Austria Micić and Hofmann, 2009 Octylphenol Maximum – 0.035 mg/kg Austria Micić and Hofmann, 2009
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Table A-4 (cont.) Concentration ranges of compounds detected in bed sediments Compound Mean (min; max) Country Reference μg/kg DW Polychlorinated dibenzo -p-dioxins and dibenzofurans(PCDD/Fs) Min; Max in pg TEQ/ g DW PCDD/F 0.1; 15.6 USA Eljarrat and Barcelo, 2004 PCDD/F 0.4; 12 Austria Eljarrat and Barcelo, 2004 PCDD/F 0.1; 17.5 Germany Eljarrat and Barcelo, 2004 PCDD/F 0.08; 9.4 Russia Eljarrat and Barcelo, 2004 PCDD/F 0.4; 3.7 Spain Eljarrat and Barcelo, 2004 PCDD/F 1.8; 7.7 Spain Eljarrat and Barcelo, 2004 PCDD/F 0.02; 24 Japan Eljarrat and Barcelo, 2004 PCDD/F 0.04; 4.4 Korea Eljarrat and Barcelo, 2004 PCDD/F 223; 250 USA (polluted) Eljarrat and Barcelo, 2004 PCDD/F 10; 761 USA (polluted) Eljarrat a nd Barcelo, 2004 PCDD/F 20; 230 Finland (polluted) Eljarrat and Barcelo, 2004 PCDD/F 100; 59 000 Finland (polluted) Eljarrat and Barcelo, 2004 PCDD/F 434; 923 Netherlands (polluted) Eljarrat and Barcelo, 2004 PCDD/F 352; 1849 Netherlands (polluted) Elj arrat and Barcelo, 2004 PCDD/F 1.1; 150 Norway (polluted) Eljarrat and Barcelo, 2004 Sum of DDT (dichlorodiphenyltrichloroethane) – p,p’-DDT + p,p’-DDD + p,p’-DDE
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APPENDIX F Figure A - 1 A list of potential contaminants in paper production (DoE, 1996a)
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