Wiener Mitteilungen Wasser Abwasser Gewässer

WIENER MITTEILUNGEN WASSER ABWASSER GEWÄSSER

Sewage Sludge Disposal sustainable and/or reliable solutions

Band 171 - Wien 2001 WIENER MITTEILUNGEN WASSER ABWASSER GEWÄSSER

Band 171

Sewage Sludge Disposal sustainable and/or reliable solutions

ÖWAV / EWA - Workshop- Wien 2001 Technische Universität Wien 10. - 11. September 2001

Herausgeber Prof. Dipl.Ing. Dr. H. Kroiß Technische Universität Wien Institut für Wassergüte und Abfallwirtschaft Veranstalter

Österreichischer Wasser- und W Abfallwirtschaftsverband

A Marc - Aurel - Straße 5 V 1010 Wien

European Water Association

Theodor-Heuss-Allee 17 53773 Hennef Germany

Institut für Wassergüte und Abfallwirtschaft TU- Wien

Karlsplatz 13 / 226 1040 Wien

Institut für Wassergüte und Abfallwirtschaft Karlsplatz 13/226; 1040 Wien Tel: + 43 1 58801-22611 Fax: + 43 1 58801-22699 Mail: [email protected]

Druck: Riegelnik 1080, Piaristengasse 19 ISSN 0279 - 5349 ISBN 3 - 85234 - 062 - 4 Contents

Le Moux, J., Gazzo, A 1 - 10 Disposal and recycling routes for sewage sludge: Sociological acceptance in Europe

Hahn, H. 11 - 20 Agricultural use of sewage sludge – a controversial issue

Bode, H., Schmitt, N. 21 - 32 New Sludge disposal concept 2000 of the River Association Ruhrverband

Brunner, P.H. 33 - 44 The role of sewage sludge in the context of the regional materials management

Böhm, R. 45 - 60 The hygienic aspect of sludge application in agriculture

Evans, T. 61 - 76 Marketing of sludge and quality assurance

Borraz, O. 77 - 88 The socio-economic problem – how to co-ordinate the many different interests and players affected by sludge application in agriculture

Piekema, P. 89 - 102 P recovery from sludge (in the context of P management)

Leitzinger, C. 103 - 112 Sludge disposal of the city of Zurich (co-incineration, actual and future options) Klager, F., Kroiss, H., Tikovsky, F. 113 - 130 Raw sludge incineration in Vienna (3 Mio PE) and its implications on waste water treatment (20 years of full scale experience)

Balmér, P. 131 - 142 Sludge treatment and disposal strategies in Sweden

Jepsen, S.E.. 143 - 156 Sludge handling and disposal strategies in Denmark

Schmidt, T. 157 - 166 Sludge disposal management in the context of regional waste management

Pollak, M. 167 - 180 Soil protection aspects of sludge application in agriculture

Kroiß, H. 181 - 184 Soil protection aspects of sludge application in agriculture Preface

In Europe, but also in many other countries of the world the necessity of water protection by waste water treatment is commonly accepted today. One of the consequences of waste water treatment is the production of sewage sludge. Those responsible of fulfilling the legal requirements for waste water treatment have to find sludge disposal methods taking into account that sludge production cannot be avoided or stopped. Sludge treatment and disposal have to comply with the following prerequisites:

S Sustainability (Health, resource and environmental protection aspects) S Reliability of disposal at any time (operational aspect) S Economical feasibility (cost minimisation aspects) S Public acceptance (agriculture, trade, retailers, consumers, etc.)

The EU-commission is on the way to develop a new guideline for agricultural use of sewage sludge in order to enhance the idea of recycling of the valuable compounds and to minimise the risk for the society and the environment.

The goal of the Workshop held in Vienna, organised in co-operation of the Austrian Water and Waste Management Association and the European Water Association was to bring together the expertise of European professionals coming from different disciplines and different countries involved in sludge disposal problems in order to discuss feasible solutions.

This booklet contains the material presented at this workshop together with a conclusion. We hope that this publication can contribute to spread knowledge and experience to a broad range of professionals in order to improve the discussion on solutions of a rather complex problem which finds public awareness mainly in the case of negative aspects or impacts. It seems that the socio-economic and political aspects need as much attention as the technological and organisational ones.

Disposal and recycling routes for sewage sludge: Sociological acceptance in Europe

J. Le Moux and A. Gazzo Andersen - Environment Risk Consulting

The debate on sludge recycling and disposal has recently been the target of growing interest. This is due to the fact that some concern was expressed about the potential risks of the agricultural use of sludge for health and the environment as early as the beginning of the 1990s. Therefore, most of the debate on sludge has focused on this route (past and present debate on disposal routes is not focused on sludge but relates to waste in general).

The debate on the use of sludge in agriculture originated mainly in Northern Europe at the beginning of the 1990s, before gaining in intensity from 1995 onwards. Analysing the context of this period is crucial to understanding the various stakeholders' attitudes, motivations and constraints concerning the use of sludge. In particular, the recent health "scares" related to GMOs (Genetically Modified Organisms), dioxins, and BSE (Bovine Spongiform Encephalopathy, that is, "mad cow disease") have cast doubts on the safety of the food products on the markets and on the ability of existing regulations and controls to minimise human exposure to potential risks.

The concern expressed about food safety is also related to growing pressure on the agricultural sector, which in certain countries is considered by consumer associations or nature protection associations as being too focused on intensive production and not sufficiently concerned about the impact of its activities on health and on the environment.

The above holds true for most European countries, however, certain countries are under considerable pressure from both sewage sludge, i.e. a high rate of production per inhabitant, and from other fertilising materials, in terms of nitrogen and phosphate content. This is one reason why the debate has not been 2 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna the same in all countries and has been most heated in the Netherlands, Flanders and Scandinavian countries.

Analysis by country

Past and current events show that it is possible to divide countries up into the following groups:

S In the Netherlands and Flanders, the debate on the use of sludge in agriculture is over, as the regulatory requirements have prevented almost all use of sewage sludge in agriculture since 1991 in the Netherlands and 1999 in Flanders.

S In countries such as Denmark and the United Kingdom, the debate is now mostly over. In Denmark, new regulations on the use of sludge in agriculture (Statutory Order no. 49 of January 20, 2000 on the Application of Waste Products for Agricultural Purposes) have played a large part in ending the debate, as they are considered sufficiently strict to reduce risks to an acceptable level. In the United Kingdom, the debate on sludge recycling was heated until an agreement was reached in September 1998 between Water UK, representing the 14 UK water and sewage operators, and the British Retail Consortium (BRC), representing the major retailers. In addition, farmers' associations support the agricultural use of sludge, both for economic and for agronomic reasons.

S The cases of Germany and Sweden are special. In Sweden, a voluntary agreement was signed in 1994 between the Swedish Environmental Protection Agency (SEPA), the Swedish Federation of Farmers (LRF) and the Swedish Water and Waste Water Association (VAV) concerning quality assurances relating to the use of sludge in agriculture. However, in October 1999 the LRF recommended that their members stop using sludge because of concerns about the quality of sludge. In Germany, opinion has recently swung in favour of agricultural land spreading, mainly because this practice is considered economically viable and it is considered that the potential risks are sufficiently reduced by the existing legislation. However, political developments in 2001 have considerably heated the debate, which is quite J. Le Moux and A. Gazzo 3 Disposal and recycling routes for sewage sludge: Sociological acceptance in Europe

high at present as some Länder support an increase of regulatory constraints on sludge landspreading.

S In Austria, France and Walloon, a national (or regional) agreement is currently under negotiation between the different parties, and hence the debate is heated. The situation is particularly tense in France where the farmers' unions supported, until recently, the development of the agricultural recycling of sewage sludge, on the condition that additional quality controls and an insurance fund system were set up. The situation has now changed, as farmers' unions (the FNSEA and CDJA) have asked for a ban on the use of sewage sludge, officially because the current methods used are not considered to be sufficient to address the risks related to the agricultural recycling of sludge.

S In Finland and Luxembourg, the farming community is generally hostile towards the use of sludge for land spreading, mainly because of the pressure to use animal manure for land spreading. For example, the Finnish Union of Agricultural Producers asked for a ban on the use of sewage sludge for land spreading in 1990, and have renewed their stand against the use of sludge in agriculture in 2001.

S In Ireland and Portugal, farmers support, in some cases, the agricultural use of sludge, both for economic and for agronomic reasons (mainly in terms of organic matter and phosphorus content), although it is difficult to obtain information on this matter. In both countries, the use of sludge seems to be too recent an issue to generate much public debate.

S In Spain, Italy and Greece, the debate remains limited, as far as can be judged from the available information.

This summary of the debate mostly shows that the debate is more "advanced" in Northern Europe, but remains limited in Southern Europe. In addition, it is important to mention that the debate is currently heated in certain countries (Austria, Walloon, France, Germany and Sweden).

A comparison with the national legal requirements also demonstrates that "tight" legal constraints (such as very low limit values for pollutants in 4 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna sludge) do not necessarily imply a greater acceptance of the use of sludge in agriculture. The Swedish example demonstrates this best.

Finally, a major trend in the current debate on the use of sludge is clearly the increasing number of agreements regulating the use of sludge. However, whereas voluntary agreements have proven to be successful in the UK, they did not prevent the current crisis in Sweden.

Analysis by stakeholder

Identifying the main positions, attitudes and constraints on the use of sludge by type of stakeholder is difficult mainly because of the various possible attitudes within one category, and because of the possible differences from one country to another. However, on the basis of the information collected in the course of this study, it is possible to give the following summary of the main stakeholders' positions (more details on the various possible attitudes within one category of stakeholder are set out in the body of the report):

S For farmers, the main motivation for the use of sludge in agriculture is the supply of organic fertiliser at a low cost. Their main constraints come from their customers, either food industries or retailers, who have specific quality requirements. In a growing number of cases, these quality requirements include restrictions on, and sometimes the prohibition of, the use of sludge in agriculture. In this context, the main consequences for farmers associated with the use of sludge in agriculture could be a reduction in their market share and a drop in profits, as well as additional liability costs in the event of an accident. In this context, farmers require (in countries where the debate is heated) that a guarantee system be set up, which would cover them against both possible risks, in order to continue using sludge.

S Landowners are generally hostile to the agricultural use of sludge. Their attitude is based on two major concerns: liability and land value. Landowners do not want to be held liable in the event of an accident (harm to humans, animals and ecosystems) caused by the use of sludge and wish to prevent any loss in the value of their land. The European Landowners' Organisation (ELO) adopted an official position concerning sludge recycling J. Le Moux and A. Gazzo 5 Disposal and recycling routes for sewage sludge: Sociological acceptance in Europe

in agriculture in January 1999, which provides safeguards for the use of sludge. In particular, the findings of the ELO focus especially on the need to strengthen legislation, the need to "ensure that suppliers accept liability for any economic loss or damage associated with spreading sludge on their land", for instance by drawing up a pan-European model contract similar to the model contract developed by the Country Landowner’s Association (CLA) in the UK.

S The main influences on the agrifood industry are marketing and public health concerns. The industry's brand image is one of its most valuable assets and its primary concern is therefore to protect its image from being tarnished. In this sense, the industry's attitude is mainly influenced by the way in which the general public perceives the potential risks of using sludge in agriculture. As most of the members of this industry are sludge producers as well, professional associations of food industries are, in most cases, officially in favour of maintaining the use of sludge in agriculture if the quality of sludge can be guaranteed. As sludge producers, these companies are obviously seeking low-cost sludge disposal routes.

S The main motivation for food retailers is to be able to purchase agricultural products at a low cost and to secure their market share by maintaining or improving the image of the quality and safety of their products. In this context, as there is still a great deal of scientific debate on the potential risks of the use of sludge in agriculture, land spreading could be perceived as a potential threat to their image. The main concern for food retailers involves the marketing stakes regarding product quality and, therefore, the extent to which the use of sludge may have an impact, whether real or perceived, on the quality of agricultural products.

S The main motivation for waste-water treatment companies is to maintain long-term disposal and recycling routes for the sludge produced at the lowest possible cost. These companies are therefore aware of the need to maintain agricultural land spreading as a major recycling route for sewage sludge, mainly for economic reasons. In this context, these companies are willing to improve their performance beyond that required by the regulations in order to protect the existing routes for sewage sludge. They are also aware of the need to improve practices, and also insist on the need to 6 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

introduce national policies aimed at improving and controlling the quality of waste water entering the sewers.

S The main waste management companies do not exclusively focus their business on sludge recycling. However, the main economic driver behind their subsidiaries specialised in organic waste management has led them to increase awareness of the importance of sludge quality control and of improving land spreading processes. In this respect, service quality assurance could become standard practice in Europe. In addition, waste management companies are increasingly developing the use of composted sludge, as compost has the advantage of reducing odours and of being a commercially viable product.

S Communities are in most cases seeking to maintain the existing disposal and recycling routes for sewage sludge that are both economically viable and safe in terms of health. In addition, communities are subject to strong pressure from their voters and are therefore concerned about limiting the "water bill". The "NIMBY" factor is also an important element which makes a difference between acceptance in rural and in urban communities.

S In most cases, national authorities have implemented policies supporting the use of sludge in agriculture, as it is considered to be the best economic and environmental option to deal with the increasing quantities of sludge produced. In this context, national authorities are seeking to increase confidence in the quality and safety of products cultivated on sludge fertilised soils.

S Consumer associations and nature protection associations have both played only a minor role in national debates on sludge recycling. Most consumer organisations involved in the debate on the use of sludge in agriculture have been largely preoccupied with food safety. In this respect, some consumer associations are concerned that the use of sludge in agriculture does not offer sufficient guarantees. The limited participation of consumer associations and the general public in the debate on sludge recycling can be explained by the lack of information made available to the public on these issues. J. Le Moux and A. Gazzo 7 Disposal and recycling routes for sewage sludge: Sociological acceptance in Europe

Simplified stakeholder ’s position concerning use of sludge in agriculture

Water and Farming Industrieswaste Local National Citizens community industry authorities authorities

Ministries WaterWater Ministries FoodFood treatmenttreatment Communities,Communities, andand other other ConsumerConsumer LandownersLandowners companiescompanies plantsplants and and townstowns relevantrelevant organisationsorganisations companies companies bodiesbodies

FarmersFarmers Waste Nature RetailRetail Waste Nature professionalprofessional managementmanagement RegionsRegions protectionprotection companiescompanies companies organisations representativesrepresentatives companies organisations

Individual LocalLocal Individual inhabitants Farmers inhabitants Farmers organisationsorganisations

Legend : : officially favourable : favourable under certain conditions : reluctant

The analysis of the stakeholders' positions shows that the main areas of consensus on sludge disposal and recycling routes are that the growing quantities of sludge must be treated in the aims of keeping both environmental and economic costs as low as possible. Similarly, improving practices, both with regard to the treatment and the use of sludge, is now considered as essential. In the context of uncertainties concerning the potential impacts on human health and the environment of the various disposal and recycling routes, all stakeholders are calling for additional research, in order to increase confidence in the use of sludge in agriculture.

Reducing constraints and encouraging the recycling of sludge

In order to encourage the recycling of sludge, the following should be taken into account:

S The development of agricultural recycling depends largely on the possibilities to improve the quality of the sludge itself and increase confidence in sludge quality. This implies the prevention of pollution of the waste water at source by reducing the possibilities for heavy metals and 8 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

organic compounds to enter the waste water sewage system and improving sludge treatment as well as ensuring the monitoring of sludge quality. These technical solutions however require major investment from the water companies or local authorities in charge of treating the waste water. The possibility to certify the treatment processes involved and the quality of sludge, either through independent "sewage sludge audits" or by the certification of sludge production and treatment processes, could help to increase confidence in sludge quality. Similarly, the quality standards of sludge recycling practices also need to be guaranteed, especially for agricultural recycling.

S One of the main issues with regard to sludge recycling in agriculture is the setting up of guarantee funds or insurance systems in order to cover any loss of profits, damages or other costs related to the use of sludge in agriculture. This would partially address the issue of liability, which is a vital concern for farmers and landowners in the debate over the use of sludge. In addition to economic instruments, legal provisions could be introduced to regulate producer liability.

S National regulatory requirements vary greatly from one country to another. In this area, national regulations, based on the same scientific grounds, should be considerably improved by the next Directive on sludge use, in order to provide long-term perspectives for the use of sludge. With regard to increasing confidence in the use of sludge, standardisation initiatives (continuation and completion of CEN TC 308 work on the production and disposal of sewage sludge) have a major role to play.

S The evolution of the debate on sludge disposal and recycling in Europe shows that the relationship between farmers and their customers (food industry and retailers) is crucial for the acceptance of the use of sludge in agriculture. Examples at national level show that an agreement at European level between representatives of food industries, retailers, farmers and sludge producers could enhance mutual confidence and information transfer. In this respect, efforts could be made to improve communication between the major stakeholders, for example by creating "contact points" similar to the national committees on sludge set up in several Member States. J. Le Moux and A. Gazzo 9 Disposal and recycling routes for sewage sludge: Sociological acceptance in Europe

S The current state of the debate on sludge recycling and disposal routes clearly shows that the current uncertainties over possible risks for human health and for the environment play a major part in the resistance against expanding various sludge recycling routes. The areas where scientific results are the most expected by the stakeholders contacted in the course of this study are possible effects of organic pollutants and pathogens in sludge. Progress in the social and political acceptance of sludge recycling could therefore be made by promoting research on these specific aspects, publishing the research results and making them widely available. In particular, there should be better dissemination of the results of current national research programmes on the effects of the agricultural recycling of sludge on health.

S In addition to the dissemination of research results, an important effort of communication on sludge use should be carried out. In particular, tools such as codes of practice for the recycling of sludge implemented on a voluntary basis should be considered. Communication should especially aim to promote high-quality sludge (with low levels of contaminants), which could be recognised as fertilisers (or as a component of fertiliser products) at European level. The development of labels at European level would enable users to identify high-quality sludge and to distinguish it from other types of sludge or waste, thus improving the image of sewage sludge itself. Therefore, labels on products could be a useful additional tool to labels on quality assurance, for encouraging the use of sludge in agriculture. The possibilities for providing more training opportunities to specific categories of stakeholders (farmers, for example) should also be examined.

Authors: Alexis Gazzo Jan Le Moux ANDERSEN - Environment Risk Consulting 41 Rue Ybry 92576 Neuilly sur Seine Cedex, France Tel : 00 33 1 55 61 08 21 e-mail: [email protected] 10 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna 11 Wiener Mitteilungen (2001) Band 171, 11-20 Copyright © 2001; Institut für Wassergüte / TU-Wien

Agricultural use of sewage sludge – A controversial issue

H.H.Hahn Institut für Siedlungswasserwirtschaft, Universität Karlsruhe

1 Preliminary Remarks

Agriculture has since long fulfilled the role of production on one hand and protection on the other, of innovation on one side and conservation on the other. Agriculture as the oldest activity of settled mankind is in many respects also one of its most noble.

Using residuals from the treatment of spent waters, formerly referred to as sewage sludge and more recently re-named ´biosolids´ for the fertilization and structural improvement of agricultural land also has had a considerable tradition. Very early wastewater collection occurred in many areas with the aim to use this water for agricultural irrigation with the added benefit of using also its constituents. As collected wastewater was not only used for irrigation but re- introduced into the aqueous environment and therefore treated, it was logical to make use of the material separated from the wastewater stream in the course of its treatment.

As the amount of water used by household and industry increased and the intensity of agricultural production called for mechanization and intensive fertilization the formerly symbiotic cooperation of farmer and biosolids producer became more and more obsolete and agricultural sewage sludge utilization was transformed into a convenient type of disposal. – In addition the quality of some sewage sludge changed due to the growing complexity of raw materials, production emissions and household goods that all ended up in those residuals from all anthropogenic activities of settled areas, for in some sense sewage sludge is also a mirror of all of man’s present and former activities. 12 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

It is understandable that agriculture in its role of protecting on one hand its products and on the other its resources with which produce is generated hesitates to cooperate in a purely disposal oriented scheme. And it is well advised to shy back from the use of all those residuals that producing and consuming mankind rids itself off. This reflects the present very heated and unfortunately also very emotional discussion of the benefits and disadvantages of agricultural use of biosolids in Germany.

The following remarks are a summary of some of these discussions, trying to maintain a position as objective as possible1. The discussion follows the pro and contra arguments listed in the following table 1.

2 Non-discriminating use of all types of secondary raw materials can create risks, also in agriculture.

In our industrial production as well as in our consumptive behavior we have learned to think in cycles as nature has taught us. Yet, after establishing such cycles, for instance in industrial production schemes it became apparent that there must be provisions for getting rid off of unwanted or dangerous material from such closed loops if the inherent accumulation and product impairment is to be stopped.

Past and present experiences with various types of material and energy cycles can be summarized into guidelines for a reasonable use of secondary materials as follows:

S The more closed the cycle is (i.e. next to no input of the material under consideration) the larger the danger of pollutant accumulation.

S The fewer the steps are within the use and re-use of raw materials in production is, i.e. the more directly consumption follows production which

1 This contribution is a summary and translation of a more extended German discussion given at a meeting of ATV-DVWK at Würzburg in 2001. H.H.Hahn 13 Agricultural use of sewage sludge – A controversial issue

then is followed again by the same production, i. e the more homogeneous the partners are in such cycles, the more critical is the quality impairment.

S The larger the number of additional or production aiding substances is, the higher is the ballast in the recycled material. The more a product consists of secondary raw material the higher the efforts in stopping pollutant accumulation must be.

S The more a product consists of secondary raw material the higher the efforts in stopping pollutant accumulation must be.

Table 1: Arguments for and against agricultural use of biosolids.

CONTRA agricultural use of biosolids PRO agricultural use of biosolids

As it is known from industrial water Agricultural use of water and also management: Closing water and spent waters: Such recycling of water other material cycles without leads logically to the use and pollutant export can lead to recycling of water constituents. dangerous accumulations.

Agricultural use of biosolids should There are more and more positive not be motivated by arguments of examples of the reasonable use of cost minimization and convenient secondary raw materials. disposal.

Importing biosolids of “unknown Limiting kind and amount of materials origin” onto agricultural areas can that are transported directly or cause specific damages. indirectly by (waste)water in order to maintain the option of agricultural use of the residuals of–water treatment is also a beneficial imperative for the overall sewage collection and treatment concept. 14 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

We have learned that agricultural use of biosolids can be a very expedient method of cost minimal disposal. However, this is the wrong type of argument: Agricultural use of biosolids should not at all be motivated by arguments of cost minimization and convenience maximization. If we would summarize the past and present experience it would read as follows:

S Historically wastewater constituents have been considered a significant side benefit for agricultural soils if sewage was used for irrigation.

S Then, as sewage collection and wastewater treatment became intensified with the very dynamic industrialization for instance after World War II there was definitely a phase of planning and building predominantly wastewater treatment plants without the simultaneous planning and building of sludge treatment facilities.

S In some instances this led to an emergency situation in the handling and safe (landfill) disposal of the produced sewage sludge and the pressure on agricultural use/disposal was high.

S The subsequent development of sludge handling processes and the construction of treatment facilities have taught us that sludge treatment and disposal can be as expensive as wastewater treatment (or even more expensive). – From that point of view it was understandable that the (economic) advantages of agricultural use were argued.

S In the phase of indiscriminant wastewater collection and treatment there were residuals produced that reflected more the complexity of today’s production and consumers spectrum than the promise of nutrients and structural improvement of agriculture. – And consequently there were undoubtedly cases of agricultural use that should not have occurred.

S Presently we witness another imparity in this field: the option of thermal use of sewage sludge has been developed to such a degree that the capacities for co-incineration of biosolids and conventional energy carriers are larger than the demand; this causes irresistible offers at low, non-market prices.

In some instances of sewage sludge utilization on agricultural areas in the past we have imported non-degradable and unwanted or even dangerous material H.H.Hahn 15 Agricultural use of sewage sludge – A controversial issue into these soils. This has caused specific damages. – To be fair, this has not occurred in a scale that would be alarming. But it has occurred either for reasons of carelessness or for the simple reason of seeking short-term benefits.

And it is this type of black-sheep behavior of indiscriminant disposal that has led to the development of a very tight network of regulations and supervision. From this we have learned the following:

S Mass-balances must be done as complete as possible for all substances used (or imported) on agricultural land, where in addition to the input all output and all possible transformations are quantitatively described.

S If import of questionable substances leads to loadings that are critical then not only one source of input but all must be scrutinized.

S Simultaneously we need information on permissible loadings (for instance specific heavy metals on soils used for specific crops); these permissible loadings or maximum concentrations are obtained from bioaccumulation factors, maximum daily intake factors in (human) nourishment and transfer functions for instance from a given soil to a specific plant and from there to the (human) food chain.

S Such data exist in a rather small number of instances; but the existence of those illustrates that a rational argumentation is possible and it also describes the type of information gather necessary.

3 Secondary raw materials become more and more valuable, also in water technology

Very early it was shown even in regions with relative abundance of water that agricultural use of spent waters was necessary. This recycling of water logically led to the use and recycling of water constituents that were removed in the course of pretreatment of irrigation waters as well.

Until very recently statistics on the agricultural use of biosolids in European countries (as for instance published by the European Water Association) show a 16 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna widespread use of these resources and therefore also a broad basis of experience. This positive as well as negative experience can be summarized as follows:

S There are acceptable and (in part scientific) proven limits or standards for the quality that a biosolids matrix should have so that its application on agricultural soils is beneficial.

S These standards are presently re-evaluated in the context of European legislature.

S Many sludge streams are of such quality that these limits are not at all reached. In fact there is as continuous improvement of many such sludge in terms of heavy metals content (so that various secondary fertilizers carry a lower load of heavy metals than some virgin mineral fertilizers).

S Agriculturally utilized sludge is highly quality controlled and accompanied by advice for the farmer in terms of nutrient content of the fertilizer and nutrient demand of the soil (giving the farmer a much better basis for all his decisions); this frequently leads to a lower application rate of biosolids on soil than would be permissible in general and specifically in terms of heavy metals or pollutants loading.

It has been mentioned that biosolids are valuable (secondary) fertilizer materials in addition to their contribution to structural improvement of soil matrices. In general we observe today that there are more and more positive examples of the reasonable use of secondary raw materials. And such use of raw materials becomes more and more beneficial in those instances where the store of primary raw materials begins to be exhausted as well as in those instances where the mining, producing and providing of such materials is transport- and energy- intensive.

Phosphorous, one of the main fertilizing components of biosolids, as such a raw material which begins to be exhausted in some of its natural sites. This has led to the development of recycling concepts.

S There are basically two different notions; one would be the “selective harvesting” of phosphorous from wastewaters in such amount and quality H.H.Hahn 17 Agricultural use of sewage sludge – A controversial issue

that it can be re-introduced into the overall phosphorous production cycle and, second, the “global” use of the phosphorous-rich sewage sludge as fertilizer (which contains some more fertilizer components in macro and micro fractions as well as the above mentioned potentially polluting materials form other anthropogenic activities.

S The “production” of fully re-usable phosphorous is still technically and economically in its development and can as of now not yet compete economically with the import of virginal phosphorous ores (or derivatives of that). – Thus it is reasonable to focus on and support the second concept of a more limited re-use of secondary phosphorous directly as fertilizer.

S As mentioned before this concept of agricultural re-cycling has not only had a long tradition with lots of experience collected in the course of its use but has become a vehicle of more rational analyses of farmers’ soils and soil improvement techniques.

S Yet, at the same time it must be said that a complete analysis of a specific sludge in terms of all its constituents which might even be technically feasible would be economically unadvisable or impossible. To insure oneself of the acceptable quality of a given sludge might require a complete input- output analysis for a specified region. And this is very much in keeping with the ideas of the new agriculture.

One of the only “indirect” yet most significant advantages of agricultural use of sewage sludge is to limit type and amount of materials that are transported directly or indirectly by (waste)water in order to maintain the option of agricultural use of the residuals of water treatment. It has been indicated before that there were cases of inadvertently harming agricultural soils by applying pollutant carrying sewage sludge.

These historical (and rather rare) incidences have led to careful analyses on sources of such pollutants and the control of these sources, besides intensive affords to repair the stated damage. We have learned that these sources can be found with an acceptable effort and we have also managed to control them to the degree needed. Thus, aiming for a potential use of biosolids from wastewater treatment in agriculture is also a beneficial imperative for the overall sewage collection and treatment concept: 18 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

S Historically our sewerage system has been developed primarily for domestic sewage; its collection, its routing and the concept of treating at the so-called endpoint all sewage might still be an acceptable solution today if only domestic waste is concerned. – However the introduction of urban runoff on one side and complex industrial wastes on the other, have led to a questioning of the concept of centrally collected, gravity transported, combined treated sewerage.

S Our concept of a central disposal system (collection, treatment and re- introduction into the aqueous environment) has formerly led to a dangerous dissipation of all kinds of dangerous and oftentimes anthropogenic pollutants.

S With checks on the collection system for the sake of producing agriculturally safe biosolids (for instance by strict standards for wastewater discharge into sewer systems) the overall concept of our sewerage has been improved or at least saved, be it by saving the structural stability of sewers, maintaining the well-functioning of treatments plants and guaranteeing the acceptability of discharged treated wastes and separated solids.

S If today we would relax the standards of discharge into the system, or not re- evaluate them continuously in the light of new insights because the ambitious aim of agricultural use of biosolids no longer exists then the overall situation in the operation of infrastructure and pollution control would be serious endangered.

4 Conclusions

One must not be very prophetic to predict a significant re-evaluation and re- orientation in the longstanding tradition of agricultural use of residuals from wastewater treatment. And it will be most likely that the total amount of sludge being utilized in this way will become smaller than it is now.

There are two aspects of such agricultural use of biosolids that make it worthwhile to try to maintain this option. First of all such use of secondary raw materials will remind us that there are other input streams as well as output and H.H.Hahn 19 Agricultural use of sewage sludge – A controversial issue that we must attempt to obtain an ever more complete picture of all these mass movements in the interest of our own health. And second, quantifying the requirements for good quality biosolids will provide a sound basis for the operation of our inherited disposal concepts using the well-developed infrastructure of central sewerage.

5 References

ATV (1996), Statistisches Datenmaterial, Hennef (1996)

Baumgart, H.-C., Schmelz, K.-G. (1995), „Kosten der Reststoffentsorgung/- verwertung unter besonderer Berücksichtigung privater Entsorger“, in ATV Fortbil-dungskurs Teil Schlammbehandlung und –verwertung, Hennef (1995)

Baumgarten, H-L. (1984), „Zum Einengen und Schließen von Wasserkreisläufen in Papierfabriken“, AVP Jahrestreffen 1983, Wochenblatt für Papierfabrikation 1984, 31-36

Dunbar, C. (1912); „Leitfaden der Abwasserreinigungsfrage“, 2. Auflage, Olden-bourg, Berlin (1912)

Friedrich, H., personal communication (2001)

Jeanmaire, N. personal communication (2001)

Kloke, R., Materialien zum ATV Fortbildungskurs D3, St. Augustin (1985)

Matthews, P.(1995), „Future prospects for sewage sludge disposal“, EWPCA Workshop, Urban Wastewater Treatment Directive, Hamburg, (1995)

Valdmaa, K. (1986): "Long-Term Field Trials with Wastewater Sludge in Comparison with Farmyard Manure and Commercial Fertilizer", in: "Recycling in Chemical Water- and Wastewater Treatment", ISWW Reihe Universität Karlsruhe, Bd. 50, Karlsruhe 20 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

Author: Prof. Dr. Ing. E.h. H.H.Hahn, Ph.D. Universität Karlsruhe Institut für Siedlungswasserwirtschaft Adenauerring 20 D-76128 Karlsruhe Telefon +49-721/608-2457 Fax: +49-721/607151 e-mail: isww@iswws1. bau-verm.uni-karlsruhe.de http://isww.bau-verm.uni-karlsruhe.de/ 21 Wiener Mitteilungen (2001) Band 171, 21-32 Copyright © 2001; Institut für Wassergüte / TU-Wien

New Sludge Disposal Concept 2000 of the River Association Ruhrverband

H. Bode and F.Schmitt Ruhrverband, Germany

"All expositions concerning the treatment and utilization of sewage sludge must not conceal the fact that wastewater treatment must lead to the final disposal of the sludge. A wastewater treatment plant that does not meet this requirement is useless. Even when the sewage sludge is incinerated or combusted there remain ashes which have to be disposed of."

Imhoff, K. (1951)

1 Introduction

Within the catchment area of the Ruhr river basin, covering about 4,500 m2, the Ruhrverband (Ruhr River Association) is responsible for both water quantity and water quality management. It operates 89 wastewater treatment plants, about 500 stormwater treatment plants, as well as 5 impounded lakes situated along the course of the river. The disposal of wastes such as sewage sludge, screenings, grit, drifting refuse and river sediments also falls within the scope of its remits. In 2000, Ruhrverband has established a new, future-oriented waste management concept that aims at environmental sustainability, disposal safety, economic efficiency and good operational practicability. In the upcoming years, approximately 60,000 t DS/a (tons of dry solids/year) of sewage sludge, 3,100 t DS/a of screenings, 3,800 t DS/s of grit and 500 t DS/a of drifting refuse will have be disposed of. 22 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

2 Ruhrverband’s Current Disposal Situation

In compliance with the current waste legislation of the state of North-Rhine- Westphalia, in general, and the special act under which the association was founded, in particular, the Ruhrverband is fully responsible for any waste generated in its facilities. Among the relevant waste categories are sewage sludge, screenings, grit, and drifting refuse from the impounding reservoirs. Like many other parties held responsible by law for waste disposal, also the Ruhrverband has passed through many stages of waste management mainly influenced by public acceptance and statutory orders. Before entry into force of the first sewage sludge ordinance in the early 80s, the bulk of all sewage sludge had been used in agriculture. With the metal-working industry being concentrated in the catchment area of the Ruhr river, it soon turned out that the new limit values could no longer be met. In response, on one hand a number of sewage sludge mono-landfills were built and on the other hand (where possible) the quality of sewage sludge was improved by intensified controlling of indirect discharging polluters. With this strategy it was possible to keep disposal costs at a low level. Consequently, the waste balance for the year 1998 exhibits a portion of around 63% for the dumping of sewage sludge on landfill sites most of which owned and operated by the Ruhrverband. And as no less than 32% of the overall sludge quantity were reused in agriculture and for recultivation purposes, only 5% had to be incinerated. In 1998, a total of around 82,770 t DS of sewage sludge – including not only the residuals from current operations but in addition some 17,000 t DS of old sludge from interim storage sites – were disposed of.

In the same year, an amount of 2,470 t DS of screenings had to be handled. With 1,530 t DS, the major part was incinerated in municipal waste incineration plants and the remaining portion dumped on external public landfills.

The situation for the disposal of grit was as follows: in 1998, some 3,970 t DS accumulated, 2,720 t DS of which were sent to the Ruhrverband’s own landfill sites and interim storage places, while 1,080 t DS were deposited on external landfills and 170 t DS used for composting purposes.

The 780 t DS of drifting refuse from the Ruhr reservoirs were completely composted in the association's own composting plant. H. Bode and F.Schmitt 23 New Sludge Disposal Concept 2000 of the River Association Ruhrverband

sewage sludge (82,770 t DS)

composting others recultivation 0,4% 21%

incineration 5,5% utilization by agriculture 10,6% landfills of Ruhrverband municipal landfills 53,5% 9,0%

screenings (2,470 t DS) grit (3,970 t DS) others 1,0% municipal intermediate landfills of landfills storages Ruhrverband 35,2% 36,3% 32%

municipal incineration utilization landfills 63,8% composting 27% 4%

Figure 1: Waste Balance of Ruhrverband in 1998 (DS = dry solids)

In the course of the last three years, the restrictions on the dumping of wastes with organic loads imposed from the year 2005 at the latest by the TA Siedlungsabfall (technical instructions for municipal waste management, (N.N., 1993)) have triggered a price war on the waste disposal market. As a result, the disposal costs have decreased markedly (Figure 2). To enhance comparability, also the pretreatment and transport costs of the different disposal options have been considered. For the traditional disposal routes 'agriculture' and 'recultivation', the orders placed by Ruhrverband averaged € 245/t DS and € 275/t DS respectively. Sewage sludges bound for municipal landfills were delivered at an average price of € 270/t DS. This compares with the elevated costs for incineration which, being essentially a function of the required pretreatment, were in the range of € 390/t DS. 24 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

600 agricultural utilization composting/recultivation landfilling incineration avg. 245 €/t avg. 275 €/t avg. 270 €/t DS DS DS avg. 390 €/tDS 500 ]

DS 400

300

200 specific costs [€/t

100

0 9 9 9 8 6 6 6 3 7 6 8 30 12 20 20 20 20 12 10 34 34 34 45 20 10 10 44 42 62 30 26 25 95 30 33 33 30 30 43 36 dry solids [%] disposal pretreatment

Figure 2: Specific Costs of different Sludge Orders for Sludge Disposal incl. Pretreatment

3 Future Waste Disposal Concept

3.1 Legal Requirements for Waste Disposal

Over the last decade, waste legislation has undergone significant changes, both at national and European level, which have affected the waste disposal scenario at Ruhrverband. The federal, nation-wide applicable technical instructions for municipal waste management established by the TA Siedlungsabfall (TASi) (N.N., 1993) rule out the depositing of solid wastes with a volatile organic content above 5% from 2005 onwards. Hence sewage sludges that naturally have an organic content greater than this 5-%-limit will have to be pre-treated by incineration or mechanical biological treatment. Though, in 1993, many experts and insiders were not so sure whether the TASi would be realised at all and despite controversial discussions on how things might turn out, the Ruhrverband immediately started to develop a new waste disposal concept with H. Bode and F.Schmitt 25 New Sludge Disposal Concept 2000 of the River Association Ruhrverband incineration as the key technology for the bulk of sludges produced in its facilities.

However, the ongoing political debate of the last few months has shown once again that incineration and subsequent depositing or utilization of the ashes is and will remain the safest method of sludge disposal at least for the next 10 years. Presently, a very focussed discussion is under way with regard to the traditional use of sludge in agriculture. While so far the problem of sewage sludge utilization has more or less been seen in isolation (KlärschlammVO, sewage sludge ordinance (N.N., 1992)) it is now being increasingly understood within the context of a holistic approach to environmental legislation geared to a sustainable waste management. For one thing, the act on soil conservation and protection in Germany and, for another, the law of fertilisers will doubtless have an impact on the pending sewage sludge ordinance (scheduled to come into force in 2002).

We at Ruhrverband assume that the German requirements will turn out to be even more stricter than those defined in the EU-Sewage Sludge Directive (N.N., 2000). And we think we are on the right course, as the utilization of sewage sludge in agriculture is going to play just a minor role in our future disposal concept. Figure 3 shows how an integrated waste management scheme might look like in 2005 and describes the disposal routes for the different types of waste. 26 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

stabilized sludge grit screenings flotsam

sludge dewatering lagoons 48 000 t DS 3 800 t DS 3100tDS 500 t DS 12 000 t DS

stationary grit-washing screening press mobile dewatering dewatering sort

44 000 t DS 10 000 t DS

municipal waste sludge incineration thermal sludge composting/ drying incineration mechanical- biological 1700 t DS gypsum salt treatment products of 250 t DS exhaust gas hazardous cleaning and drying waste

6 000 t DS 26 000 t DS 10 000 t DS 3100tDS

utilization by utilization of slag utilization of utilization utilization utilization of flotsam agriculture landfilling of slag dried sludges of grit of slag landfilling of flotsam

Figure 3: Disposal Routes for Waste from Wastewater Treatment in 2005

3.2 Future Disposal of Screenings

Considering the standards stipulated by the TASi and the Abfallablagerungsverordnung (N.N., 2001), the preferred solution for the disposal of screenings is thermal treatment in MSW incinerators which has already become normal practice for a fair portion of Ruhrverband's screenings. Prior to being incinerated, the screenings are dewatered in screening presses up to a dry solids content of 30 to 50%. Due to the availability of several disposal options, present-day prices for the incineration of screenings are the lowest ever. However, when the regulations will come into effect in 2005, requiring all MSW to be incinerated, it is expected that the incineration costs charged by MSW incinerators will increase. The new concept provides incineration of of 3,100 t DS per year which corresponds to about 7,500 t of screenings.

3.3 Future Disposal of Grit

Over the last years, apparatus construction in the field of grit washers has seen a rapid development. The hitherto used conventional grit washers did not allow the organic portion of the screenings to be decreased to a degree that would come at least somewhat closer to the envisaged 5%. So this is not an appropriate H. Bode and F.Schmitt 27 New Sludge Disposal Concept 2000 of the River Association Ruhrverband process step with which to prepare a waste product that can be landfilled in compliance with the new regulations. The Ruhrverband has decided all grit and sand resulting from wastewater treatment to be treated in grit washers. Thus it will be possible to meet the standards of landfilling as well as of utilization, for instance, in the building materials industry. As it is not reasonable, for economic reasons, to equip all wastewater treatment plants (WWTPs) with grit washers, only the large facilities will be retrofitted. Grit from smaller facilities will be transported to central grit washers located in the larger WWTPs. A major amount of grit will be treated in a two-stage grit washing plant owned and operated by a neighbouring water association. Around 3,800 t/a DS are expected to be disposed of in the years ahead whereby the material utilization of the grit, for example, in the building materials industry, is strongly favoured.

3.4 Future Sludge Disposal

It has been calculated that upon completion of the retrofitting programme for nitrogen elimination under way at all WWTPs of the Ruhrverband, around 60,000 t DS per year of sewage sludges from regular operations will have to be disposed of. To satisfy the requirements of the relevant law on waste defined by the Federal state, Ruhrverband has to guarantee disposal security for a period of no less than 10 years. Given the current political discussion on the issue of agricultural utilization and given the landfilling regulations stipulated by the TA Siedlungsabfall, this proof of disposal security can actually only be provided if the sewage sludges are incinerated. Co-combustion of sludge in coal-fired power stations or cement factories is, in principle, possible, but has repeatedly been the subject of vehement criticism in the past, so that Ruhrverband favours mono-combustion in fluidized-bed incineration plants, licensed in accordance with the 17th BimSchV (federal immission control ordinance), for the major amount of its sludges.

Following some thorough negotiations with several outside bidders and the planning and approval of an incineration plant of our own – that will not be built because it has come under some political pressure – the following strategy has been developed: 15,000 t DS of the overall quantity of sludges generated will be incinerated in the mono-combustion facility of the Wupperverband (Wupper River Association), located at Wuppertal-Buchenhofen. This will be done under a long-term contract due to expire in 2014. Some further 29,000 t 28 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

DS will be incinerated in a mono-combustion plant at Werdohl-Elverlingsen jointly owned by Ruhrverband and Elektromark (an energy supplier in the Sauerland region). It is still under construction and scheduled to go on stream next summer. 10,000 t DS will be dried to a solids content of 95% DS in the drying plant at Hattingen WWTP owned and operated by Ruhrverband prior to being delivered to various disposal facilities. The remaining 6,000 t DS are planned to be used in agriculture if this still will be possible (Figure 4).

In the decision-finding process in favour of the incineration plants, some further operational and economic criteria played an important role as, for example, the necessity to appropriately adapt the sludges to the purposes of the disposal route selected so to say at the source, i.e. inside the WWTP. This 'customisation' starts with the stabilisation whereby, depending on the process applied, different degrees of stabilisation may be achieved. And the degree of stabilisation influences, in turn, the dewatering behaviour. To give an example, it was found that in simultaneous aerobic stabilisation intermediate storage periods of several months or even several years – depending on the available storage capacity – markedly improve the consolidation behaviour of the sludge (Klopp, R., 1990).

t DS/a

70.000 60.000 50.000 40.000 30.000 20.000 10.000 0 1998 1999 2000 2001 2002 2003 2004 > 2005

landfilling utilization in agriculture and recultivation

drying and utilization incineration

storage

Figure 4: Changes in Disposal Strategy of Ruhrverband's Sludges H. Bode and F.Schmitt 29 New Sludge Disposal Concept 2000 of the River Association Ruhrverband

Disposal in incineration plants can be optimised by employing highly efficient dewatering units to minimise both transport and incineration costs which are a function of the solids content. Inorganic conditioners (like lime and iron) should not be used as they might lower the calorific value and cause technical problems, due to mass increase and adversely affect the combustion efficiency.

It goes without saying that while striving to select the best processing route, a close eye should not only be kept on the primary target, but also on secondary expenditures. That means, any 'side-effects' that might be associated with a specific treatment process should be identified such as, for instance, high personnel costs and/or operational expenses (ATV, 1999). Attention must also be paid to the sludge liquor. In case of low reserve capacities or elevated requirements as to effluent quality, the sludge liquor is to be managed in such a way that the limit values for nitrogen in the effluent will not be exceeded.

To allow an optimum timing for the conclusion of a contract, a careful assessment of the economic efficiency is needed. On the one hand, some money may indeed be saved by postponing the entry into the incineration market as long as possible. On the other hand, the incineration costs are beginning to rise again. Comparative calculations should be established under consideration of various dates of market entry and incineration costs for long disposal periods. Preferably long contract terms should be agreed upon. To find the best partner on the marketplace, it takes a good relationship of mutual trust and a careful weighing of all economic aspects. Along these guidelines, Ruhrverband finalised its cooperation contract with the Wupperverband, which will be valid until 2014, as early as in 1999.

Figure 5 shows the catchment area of Ruhrverband, the existing and planned incineration facilities for sewage sludge as well as the thermal sludge drying site at Hattingen WWTP. 30 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

Oberhausen Essen Bochum Schwerte M Mülheim öh Witten ne r Menden Möhne reservoir uh Ru Duisburg R hr H Arnsberg

Trocknungsanlage ö L n R

n Rh e ö n e

ei Hattingen n h n r Hagen e Iserlohn Brilon

V Meschede Velbert e ep o Sorpe n l n m E reservoir e Ennepetal Altena N

g R

e u

Henne reservoir r Werdohl-Elverlingsen W h r e n Plettenberg n Lüden- e scheid Ennepe reservoir 14 Talsperren (davon 7 eigene) Verse Buchenhofen reservoir Einzugsgebiet( derWupperverband Talsperren ) Attendorn Schmallenberg e Lenn 101 Kläranlagen Bigge reservoir 5 Stauseen 77 Pumpwerke Olpe sludge incineration 7 Rückpumpwerke e g g i 17 Wasserkraftwerke B thermal sludge drying 377 Niederschlagswasserbehandlungsanlagen

Figure 5: Wastewater Treatment Plants of Ruhrverband and Incineration Plants

The new waste disposal concept drawn up by Ruhrverband includes detailed logistics schemes for each WWTP. These plans had to be set up in order to determine for each plant whether besides a change of the disposal route also some further modifications such as, for example, new dewatering or interim storage facilities would be required. In order to ensure a secure sequence of charging, in particular, for the planned fluidised-bed incineration plant at Elverlingsen, some comprehensive planning work had to be done to optimise the transport logistics, given the fact that the licensing authorities have set the portion of sludge to be transported by train at as high a level as 70%. This is a big challenge not only for the operators of WWTPs.

4 Final Remarks

In 4 years at the latest, which will mark the end of the transitional period provided by the regulations of TA Siedlungsabfall and of AbfAblV, the only viable variants for sewage sludge disposal will be material utilization, incineration with subsequent disposal of the resulting ashes, and mechanical / biological pretreatment. The current EU activities to redesign the sewage sludge directive [N.N., 2000 b] and the waste-management related planning initiatives under way at the Ministry of Environment in North-Rhine-Westphalia [N.N., H. Bode and F.Schmitt 31 New Sludge Disposal Concept 2000 of the River Association Ruhrverband

2000 a] clearly indicate that from 2005 onwards the utilization in agriculture will probably be restricted to very few cases. Against this regulatory background, Ruhrverband began, already at an early date, to work out a future- oriented waste management concept that ensures disposal security in the long term. As it can be expected that the prices for sludge disposal will continue to rise once the restrictions for landfilling will be in place in 2005, Ruhrverband decided to enter the incineration market some years ahead of that date. It concluded a long-term disposal contract, thereby taking advantage of the currently still moderate price level. Simultaneously, a new incineration plant is currently being built by the association in co-operation with an energy supplier which will be put into service in middle of 2002. Hence, from next year onwards, the greatest share of the sewage sludge stream generated at Ruhrverband's WWTPs, will be disposed of via the thermal route.

The waste management concept 2000 established by Ruhrverband satisfies all waste-related requirements set by the Federal state of North-Rhine-Westphalia, in particular, those relating to the 10-year-period of disposal security as well as those relating to the state government's firm intention to give priority to sewage sludge incineration. Compliance with these statutory regulations involves substantial investments. Therefore, the Ruhrverband expects from the state government the necessary planning stability and reliability to allow these investments to be written off over a reasonable period of time. And there's no denying that there will probably be further fundamental changes in waste legislation at ever shorter intervals. However, all parties and operators concerned should be granted reasonable transitional periods, as otherwise the rising wastewater and disposal charges might reignite discussions on deregulation and privatisation. 32 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

5 References

ATV Kostenstrukturen der Klärschlammbehandlung ATV-Arbeitsbericht der AG 3.1.5 „Kostenstrukturen der Klärschlammbehandlung und –entsorgung“, ka, 5/1999 Imhoff, K. Taschenbuch der Stadtentwässerung, R. Oldenbourg Verlag, München – Wien, 14. Auflage, 1951 Klopp, R. Unveröffentlicherter Laborbericht des Ruhrverbandes, Essen, 1990

N.N. Klärschlammverordnung (AbfKlärV), BGBL I 1992 S. 912 ff., 1997 S. 446 ff N.N. Abfallwirtschaftsplan für Abfälle aus Kläranlagen in Nordrhein-Westfalen – Entwurf. Ministerium für Umwelt, Raumordnung und Landwirtschaft Nordrhein-Westfalen, 2000 a N.N. TA Siedlungsabfall: Dritte allgemeine Verwaltungsvorschrift zum Abfallgesetz: Technische Anleitung zur Verwertung, Behandlung und sonstigen Entsorgung von Siedlungsabfällen vom 14. Mai 1993, Bundesanzeiger S. 4967 N.N. Schlämme – Arbeitsunterlage – 3. Entwurf Zweiter Entwurf der EU-Kommission zur Novellierung der EU- Klärschlammdirektive, Brüssel, den 27. April 2000 b N.N. Abfallablagerungsverordnung (AbfAblV), Verordnung über die umweltverträgliche Ablagerung von Siedlungsabfällen und über biologische Abfallbehandlungsanlgen vom 17. Februar 2001 BGBL Nr. 10/2001 S. 305 - 324

Authors: Prof. Dr.-Ing. Harro Bode Dr.-Ing. Ferdinand Schmitt Ruhrverband Kronprinzenstraße 37 D-45128 Essen 33 Wiener Mitteilungen (2001) Band 171, 33-44 Copyright © 2001; Institut für Wassergüte / TU-Wien

Sewage Sludge and Regional Materials Management

P.H.Brunner Institute for Water Quality & Waste Management, TU Vienna

Contribution of sewage sludge to regional material flows

Regional flows Mass DM C N P Cd [%]

Total flow 100 100 100 100 100 100

MSW 0.2 4 2 9 6 20

sludge 0.3 0.3 0.2 3 8 1

Regional nitrogen flow by food chain

nitrogen [kg/c.y]

food agriculture PHH 18 8 processing 3,7

10 4,3 3,7

agricultural processing sewage and wastes wastes MSW 34 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

Partitioning of food-derived N in households

3 nitrogen respiration [% of input] transpiration

100 human food body kitchen 13 70 feces urine

89 8 6 total food wastes to STP waste garbage sewer sewage system

MSW treatment

Regional phosphorous flow by food chain

phosphorus [kg/c.y]

food 51agriculture processing 0,4 PHH

4 0,6 0,4

agricultural production sewage and wastes wastes MSW P.H.Brunner 35 Sewage Sludge and Regional Materials Management

Partitioning of food derived-P in households

0 phosphorus respiration [ % of input ] transpiration

100 human food body kitchen 23 63 feces urine

91 9 5 total food garbage wastes to sewage STP waste sewer system

MSW treatment

Main elements in sewage sludge

element typical content [mol/kg DM] [g/kg DM] hydrogen 34 34 carbon 18 220 oxygen 11 170 silica 2.3 65 calcium 1.9 73 nitrogen 1.9 27 phosphorus 1.1 34 aluminum 0.9 25 magnesia 0.4 9 iron 0.3 20 sulfur 0.2 8 titanium 0.1 5 36 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

Inorganic trace elements

element typical content [mg/kg DM] zinc 1 000 copper 800 lead 400 silver 10 arsenic 7 cadmium 5 mercury 6 antimony 2 selenium 2 gold 1

Organic trace compounds

mg/kg TS organic compounds metals 10.000

LAS 1.000 m 1986 Zn m 1988 100 NP Pb

1 Sn- Cd OC 0,1 PHT PAK PCB

0,01 < < HCB DDE PCDD DDT 0,001 P.H.Brunner 37 Sewage Sludge and Regional Materials Management

Material flow through sludge incineration

sludge centrifuge backflow STP DEWATERING sludge

dryer condensate STP DRYING

air dry sludge other waste incineration INCINERATION aux. fuel flue gas

ESP filter ash landfill flue gas APC CONTROL

NaOH scrubber flue gas atmosphere waste water filter cake landfill NaOH neutralization treated water surface waters system boundary

Sludge total mass flow through incineration

backflow [t/d] 100 % sludge 810 centrifuge 670 STP 83 %

sludge 140

condensate dryer 74 STP 9.1 %

dry sludge 63 fuel 5 incinerator ash air 250 19 landfill 2.4 % ESP other waste 5 off gas 300 filter cake 2 landfill 0.2 % treated ww water, chemicals 230 scrubber 220 receiving waters 27 % 300 atmosphere 37 % flue gas

system boundary 38 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

Sludge dry matter flow through incineration

[kgTS/d] backflow 100 % sludge 32 000 centrifuge 650 STP 2 %

sludge 32 000

condensate dryer 15 STP 0.05 %

dry sludge 32 000

fuel 1 400 incinerator ash 18 000 landfill 56 % other waste 2 300 ESP

off gas 11 filter cake 95 landfill 0.31 % treated ww receiving water water, chemicals 27 scrubber 2 0.0062 % flue gas 5 atmosphere 0.015 %

system boundary

Carbon flow through incineration

[kg C/d] backflow 100 % sludge 7 800 centrifuge 160 STP 2 %

sludge 7 600

condensate dryer 15 STP 0.19 %

dry sludge 7 600

fuel 1 100 incinerator ash 49 landfill 0,63 % other waste 900 ESP

off gas 9 700 filter cake 4 landfill 0.05 % treated ww scrubber 4 receiving water 0.05 % 9 700 atmosphere 124 %

flue gas system boundary P.H.Brunner 39 Sewage Sludge and Regional Materials Management

Zinc flow through incineration

[kg Zn/d] backflow 100 % sludge 65 centrifuge 3.2 STP 4.9 %

sludge 62

condensate dryer 0.12 STP 0.19%

dry sludge 62

ash incinerator other waste 0,91 63 landfill 96 % ESP

off gas 0.19 filter cake 0.09 landfill 0.5 % treated ww scrubber 0.0021 receiving water 0.0032 % flue gas 0.096 atmosphere 0.15 %

system boundary

Sinks for material flows from sludge incineration

constituent atmosphere water landfill [%] carbon 124 2 0.7 nitrogen 63 38 0.7 dry matter 49 2 57 mass 37 120 2.6 mercury 14 12 72 sulfur 3.8 34 65 zinc 0.15 5 96 cadmium 0.15 5 95 40 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

Material flow by sludge land filling

sludge centrifuge backflow STP DEWATERING sludge leachate hydrosphere landfill off-gas atmosphere LANDFILL system boundary

Mass flow by sludge land filling

100 centrifuge 83 STP

0.5 atmosphere landfill +7.5 9 hydrosphere

system boundary P.H.Brunner 41 Sewage Sludge and Regional Materials Management

Dry matter flow by sludge land filling

[ % ]

100 centrifuge 2 STP

14 atmosphere landfill +74 10 hydrosphere

system boundary

Carbon flow by sludge land filling

[ % ]

100 centrifuge 2 STP

30-70 atmosphere landfill +(21-66) 2-7 hydrosphere

system boundary 42 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

Zinc flow by sludge land filling

[ % ]

100 centrifuge 5 STP

0.0003 atmosphere landfill +95 0.1-0.3 hydrosphere

system boundary

Nitrogen flow by sludge land filling

100 centrifuge 35 STP

10-20 atmosphere landfill + (45-25) 10-20 hydrosphere

system boundary P.H.Brunner 43 Sewage Sludge and Regional Materials Management

Sinks for material flows from sludge incineration

constituent atmosphere water landfill [%] carbon 124 2 0.7 nitrogen 63 38 0.7 dry matter 49 2 57 mass 37 120 2.6 mercury 14 12 72 sulfur 3.8 34 65 zinc 0.15 5 96 cadmium 0.15 5 95

Conclusions

•Sewage sludges have comparatively: - low resource potential - low pollutant potential

•Incineration - mineralizes organic compounds - reduces landfill volume by ~98 % (~65%*) - concentrates metals in ash landfill

•Land filling - concentrates metals in organic landfills - poses a long term risk due to C and N stock 44 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

References

Brunner, P.H. (1992) "Entscheidungshilfen zur Frage "Deponieren oder Verbrennen von Klärschlamm", In: Schriftenreihe des Österreichischen Wasserwirtschaftsverbandes (ÖWWV) Heft 88, Wien.

Baccini, P., Brunner, P.H. (1991) "The Metabolism of the Anthroposphere", Springer Verlag, Berlin, Heidelberg, New York, London.

Author: O.Univ.Prof.Dr. Paul H. Brunner Vienna University of Technology Institute for Water Quality and Waste Management Karlsplatz 13/226.4 1040 Vienna, Austria Tel. +43-1-58801-22641 Fax: +43-1- 5042234 e-mail: [email protected] http://awsnt.tuwien.ac.at/ 45 Wiener Mitteilungen (2001) Band 171, 45-60 Copyright © 2001; Institut für Wassergüte / TU-Wien

Public health aspects connected with agricultural utilization of sewage sludge

R. Böhm Universität Hohenheim, Germany

1 Introduction

Like other urban wastes, sewage sludge may contain different kinds of pathogens that are infectious for different species of animals and plants as well as for humans. The origin and nature of organic wastes such as different types of sludge always causes a hygienic risk in storage, collection, processing, handling and utilisation. These risks exist both when the organic wastes are generated during the treatment of industrial or municipal wastewater, and when the sludge results from industrial processing of organic material. Therefore hygienic principles must be followed in processing, storage, transport and distribution of such materials. Recycling of organic material to agriculture is a desirable aim from the point of view of saving raw materials which are of limited availability such as phosphorous, but this aim may conflict with the necessity to protect humans, animals and plants from undesired infections as well as with general aims of environmental protection. This report covers only the hygienic aspects of the use of sludge on land. However, undesired organic and inorganic pollutants can also cause risks and must be kept in mind.

2 Hygienic risks

Three main types of risks related to human and animal pathogens should be considered under public health aspects in processing and recycling sludge (BÖHM, 1995; BÖHM et al., 1996; STRAUCH, 1998)

" occupational health risks 46 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

" risks concerning product safety

" environmental risks

Occupational health considerations in collecting and processing of organic wastes and sludges are not the main subject of this contribution, more details may be found in HICKY and REIST (1975), GRÜNER (1996) and BÖHM (1998). Hygienic risks due to sludge and related products will be discussed here. This includes the direct transmission of pathogens to humans or animals and plants of agricultural importance as well as the introduction of these pathogens into the biozoenosis and environment by the application of such material as organic fertilizers.

2.1 Pathogens in sewage sludge

The basic hygienic risk is the occurrence of pathogens in sewage sludge. This is the starting point for epidemiological reflections and necessary precautions. Ta- bles 1 - 4 show a survey on such pathogens according to STRAUCH (1991).

Table 1: SELECTION OF BACTERIAL PATHOGENS TO BE EXPECTED IN SEWAGE AND SEWAGE SLUDGE, Strauch (1991), modified

Primary pathogene Secondary pathogene Salmonella spp. Escherichia Shigella spp. Klebsiella Escherichia coli Enterobacter Pseudomonas aeruginosa Serratia Yersinia enterocolitica Citrobacter Clostridium perfringens Proteus Clostridium botulinum Providencia Bacillus anthracis Multiresistant bacteria Listeria monocytogenes Vibrio cholerae Mycobacterium spp. Leptospira spp. Campylobacter spp. Staphylococcus Streptococcus R. Böhm 47 Public health aspects connected with agricultural utilization of sewage sludge

From the variety of bacterial pathogens Salmonella spp. are the most relevant since they can infect or contaminate nearly all living vectors from insects to mammals.

Multiresistant bacteria are becoming increasingly important since their transmission via the environment as well as the introduction of resistance genes into other bacteria may cause tremendous problems in human and veterinary medicine (TSCHÄPE, 1996). Among viral pathogens, enteroviruses, caliciviruses and rotaviruses are the most relevant from the point of view of environmental risks (METZLER et al. 1996). Special regard must be paid to the parasitic pathogens, not only to eggs of round- and tapeworms but to Giardia lamblia and Cryptosporidium parvum.

Table 2: SELECTION OF VIRUSES EXCRETED BY HUMANS WHICH CAN BE EXPECTED IN SEWAGE AND SEWAGE SLUDGE (STRAUCH, 1991; HURST, 1989)

Virus group Number Diseases or symptoms caused of types

Enterovirus - Poliovirus 3 Poliomyelitis, meningitis, fever - Coxsackievirus A 24 Herpangina, respiratory disease,meningitis, fever - Coxsackievirus B 6 Myocarditis, congenital heart anomalies, meningitis, respiratory disease, pleurodynia, rash, fever - Echovirus 34 Meningitis, respiratory disease, rash, diarrhoea, fever - New „numbered“ 4 Meningitis, encephalitis, respiratory disease, acute haemorrhagic enteroviruses conjunctivitis, fever Adenovirus 41 Respiratory disease,eye infections Reovirus 3 Not clearly established Hepatitis A-virus 1 Infectious hepatitis Rotavirus 4 Vomiting and diarrhoea Astrovirus 5 Gastroenteritis Calicivirus (Norwalk 2 Vomiting and diarrhoea agent) Coronavirus 1 Common cold Adeno-associated virus 4 Not clearly established but associated with respiratory disease in children Parvovirus 2 One type possibly associated with enteric infection 48 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

Table 3: SELECTION OF PATHOGENIC YEASTS AND FUNGI AND FUNGI TO BE EXPECTED IN SEWAGE AND SEWAGE SLUDGE (STRAUCH 1991)

Yeasts Fungi

Candida albicans Aspergillus spp. Candida krusei Aspergillus fumigatus Candida tropicalis Phialophora richardsii Candida guillermondii Geotrichum candidum Crytococcus neoformans Trichophyton spp. Trichosporon Epidermophyton spp.

Table 4: SELECTION OF PARASITES TO BE EXPECTED IN SEWAGE AND SEWAGE SLUDGE, STRAUCH (1991), modified

Protozoa Cestodes Nematodes

Cryptosporidium parvum Taenia saginata Ascaris lumbricoides Entamoeba histolytica Taenia solium Ancylostoma duodenale Giardia lamblia Diphyllobothrium latum Toxocara canis Toxoplasma gondii Echinococcus granulosus Toxocara cati Sarcocystis spp. Trichuris trichiura

2.1 Pathogens in sludges of other origin

The spectrum of pathogens found and in which concentrations depends on the origin of sludges. Sludge of animal origin such as from slaughterhouses or meat processing industries will generally contain mostly animal pathogens or zoonotic agents. Table 5 gives an overview of the bacterial counts found in bovine rumen content of selected species, and Table 6 summarizes the pre- valance and resistance of parasitic agents from the gut of cattle and their potential hygienic hazard. Nearly all gut related pathogens can be found in slaughterhouse effluents. If sludges are of plant origin or have been processed by using plant material, they may contain plant-pathogenic viruses, fungi, bacteria, parasites and undesired weeds. This will cause an additional phytohygienic risk if the final product is used in agriculture as fertilizer (BÖHM et al. 1997). R. Böhm 49 Public health aspects connected with agricultural utilization of sewage sludge

Table 5: BACTERIAL COUNT* INCLUDING SALMONELLA OF RUMEN CONTENT COLLECTED FOR FURTHER PROCESSING

Sample TBC EBA E. coli FCS Salmonella pH- DM Value

02.03.95 5.7x107 4.3x105 4.3x105 2.1x106 7.5x102 6.02 19.90 4.3x100 11.10.95 4.9x108 1.5x106 2.3x104 2.5x105 7.48 12.92 S. Thyphimur 08.01.96 4.8x108 2.3x107 2.3x107 7.5x106 7.5x102 6.68 19.92 (1) (2) 5.4x108 2.3x107 9.3x106 2.3x107 4.3x103 7.41 19.92 (3) 5.7x108 2.3x107 9.3x106 3.8x107 2.3x106 7.07 19.92 (4) 6.9x108 2.3x107 2.3x107 2.3x107 4.3x103 7.20 19.92 (5) 9.9x108 4.3x107 9.3x106 4.3x107 2.3x103 7.85 19.92 07.03.96 4.4x108 2.9x105 9.3x104 9.3x105 9.3x102 7.25 21.08 (1) (2) 4.6x108 2.4x106 9.3x105 2.4x106 4.3x103 7.15 21.08 (3) 8.4x107 2.4x106 2.4x106 9.3x105 2.4x103 6.79 21.08 (4) 3.6x108 9.3x107 4.3x105 9.3x105 2.4x103 7.24 21.08 (5) 3.1x108 9.3x105 9.3x105 2.4x106 4.3x103 7.16 21.08 * CFU/g TBC = Total Bacterial Count 37 °C FCS = Fecal Streptococci EBA = Enterobacteriaceae DM = Dry Mater

Table 6: PREVALENCE AND RESISTANCE OF PARASITIC AGENTS FROM THE GUT OF CATTLE AND THEIR POTENTIAL HYGIENIC HAZARD (BÜRGER AND STOYE, 1978, MODIFIED)

Parasite Prevalencea Resistanceb Priority as a hygienic hazard

Protozoa

Cryptosporidia +++ +++ 1 Eimeria spp. +++ +++ 2 Helminths Trichostrongylus spp. +++ ++ 3 Strongyloides papillosus ++ + Oesophagostomum spp. ++ ++ Fasciola hepatica ++ +++ 4 Dictyocaulus viviparus ++ 50 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

Trichuris spp. + ++ Dicrocoelium dendriticum + +++ Moniezia spp. + + Toxocara vitulorum + +++

a +++ regular ++ frequent +occasional b +++ high ++ intermediate + low

3 Epidemiological importance of sludge related pathogens

Pathogens may survive for a remarkable period of time in sludges and the environment. This is a basis for the resulting epidemiological risks. (STRAUCH 1998). Possible means of transmission are summarized in Table 7.

The direct or indirect transmission of zoonotic agents to farm animals is generally regarded as the most relevant risk factor of agricultural utilization of untreated or insufficiently treated sludge. This direct relationship between fertilizing with sewage sludge and infection in cattle fed with forage after spreading was reported by BREER (1981) for Salmonella (Fig. 1). The transmission of parasites was observed much earlier.

Table 7: EPIDEMIOLOGICAL IMPORTANCE OF PROCESSED WASTES AND RESIDUALS AND THEIR RESULTING PRODUCTS

A. DIRECT TRANSMISSION TO FARM ANIMALS CONTAMINATION OF MEADOWS INTRODUCTION OF PATHOGENS BY STORAGE AND PROCESSING CLOSE TO SUSCEPTIBLE ANIMALS AEROGENIC TRANSMISSION BY SPREADING OF MATERIALS INTO FARM LAND B. DIRECT TRANSMISSION TO HUMANS HANDLING OF CONTAMINATED PRODUCTS IN THE HOUSEHOLD OCCUPATIONAL EXPOSURE TO CONTAMINATED PRODUCTS ACCIDENTAL TRANSMISSION TO IMMUNCOMPROMISED PERSONS C. INDIRECT TRANSMISSION TO FARM ANIMALS VIA FEED FROM CONTAMINATED SITES VIA LIVE VECTORS D. INDIRECT TRANSMISSION TO HUMANS VIA INTRODUCTION OF ZOONOTIC AGENTS INTO THE FOOD-CHAIN VIA FOOD CONTAMINATED BY LIVING VECTORS R. Böhm 51 Public health aspects connected with agricultural utilization of sewage sludge

E. INTRODUCTION INTO THE ENVIRONMENT GENERATION OF CARRIERS IN THE FAUNA INTRODUCTION INTO THE MICROFLORA

Figure 1: SEASONAL DISTRIBUTION OF SALMONELLA ISOLATIONS FROM DAIRY CATTLE FED WITH FORAGE AFTER SPREADING OF SEWAGE SLUDGE DURING THE WINTER AND AFTER HAY MAKING (BREER, 1981)

Although transmission to humans via products based on sludge or containing insufficiently treated sludge in households (OTTOLENGHI et HAMPARIAN, 1987) may be a relatively rare event, this must be regarded as a real risk. In addition, accidental contact of imunocompromised persons to contaminated sludge or sludge products may result in infection. The occupational risks in processing and handling of sludge and related products must be taken into account but will not be discussed in detail. Indirect transmission to humans is of special importance, because the introduction of pathogens into the food chain via contaminated fertilizer leading to contaminated animal feed resulting in infection of farm animals and / or excretion of pathogens is of basic epidemiological significance. The risk of transmission of pathogens to human food by living vectors such as insects, rodents and birds from processing, handling and agricultural utilization of slurry should also be taken into account. 52 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

Table 8 demonstrates the importance of birds as carriers of salmonella. Sewage treatment plants have been identified as one of the sources of infection in sea- gulls. Additional means of introduction of certain pathogens were demonstrated by KÖHLER (1993). He identified a Salmonella Enteritidis lysotype in waste delivered from West-Berlin to a waste disposal site in the former GDR and followed the introduction of this pathogen via birds into the chicken populations and finally to humans via products containing eggs. This historical example can be followed in table 9.

Table 8: DETECTION OF SALMONELLA IN SEA-GULL DROPPINGS (Hellmann, 1977)

Number of Salmonella Number of Predominant References Site Samples positive Serovars Serovars

S. Brandenburg

S. Typhimurium PAGON et al. Lake Konstanz 996 6,9 8 (1974) S. Manchester

S. Newport

Steinhuder 95 9,5 6 S. Typhimurium Meer 13,9 12 S. Agona HEILMANN et al. PURIFICATION 187 S. Montevideo (1973) POND OF SUGAR PLANT LEHRTE

S. Typhimurium WUTHE, H.H BREEDING 196 12,25 12 S. Thompson (1973) COLONY S. Infantis S. Enteritidis

S. Typhimurium EDEL, W. et al. Walcheren 60 26,7 10 S. Montevideo (1972) (NL) S. Infantis

Hamburg, S. Typhimurium MÜLLER, G. WASTE 1037 35,6 S. Paratypi B 13 (1965) WATER 134 76,9 S. Manchester PURIFICATION S. Infantis PLANT R. Böhm 53 Public health aspects connected with agricultural utilization of sewage sludge

Table 9: TIME TABLE OF TRANSMISSION OF S. ENTERITIDIS (LYSOTYPE 17) FROM WEST BERLIN WASTES TO BIRDS OF THE SCHÖNEICHE WASTE DISPOSAL SITE IN THE FORMER GDR (KÖHLER, 1993)

1989 1990 1991 1992 Total ORIGIN I II III IV I II III IV I II III IV I II III IV CHILDREN 5108 23 BERLIN-WEST WASTE DISPOSAL SITE SEA GULLS 325 AND CROWS DOVE 112 ORANIENBURG CHICKEN 17 12 12 2 43 CHICKEN TRANSPORT 53 8 CAGES HUMANS ZOSSEN 1438 22 20 POTSDAM BRANDENBURG CAKE 11 2 PUDDING BLACK GROUSE 11 TOTAL 5101123151222468 23104

WILLIAMS et. al (1977) as well as several other authors (COULSEN et. al, 1983; MAYR, 1988) described the importance of vectors in the transmission of Salmonella to farm animals and humans. FOSTER and SPECTOR (1995) described specific molecular mechanisms responsible for the ability of Salmonella to survive environmental stress. This means that the introduction of pathogens in the environment leads to carriers in the natural fauna and to the introduction of transmissible undesired properties of bacteria such as antibiotic resistance plasmids into the microflora and biozoenoses. Figure 2 shows a simplified scheme of the ways in which drugs can be introduced into the environment. When these drugs are antibiotics, this means that selection of resistant pathogens can take place at every stage of distribution. This elevates the risk of spreading resistant bacteria in an uncontrolled manner. 54 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

4 Strategies to achieve hygienic safety in treatment and use of organic sludge

A compilation of bacterial, fungal, parasitic and viral pathogens for humans and animals which may be present in organic wastes is given above. Plant pathogens can also be significant if sludges other than sewage sludge are used which contain significant amounts of material of plant origin. An extensive list of phytopathogenic viruses, bacteria, fungi and seeds is given by MENKE (1992).

Since it is impossible to test treated sludge for each of the pathogenic agents which can occur, other strategies are necessary in order to assure the hygienic safety of the processed material. The first step in such a strategy is to find a representative indicator organism which can be used to analyse the product for hygienic safety as well as to evaluate the treatment process for its capability to inactivate pathogens which are of epidemiological relevance. The second step which is necessary in this connection is to define hygienic requirements for the treatment itself, since due to the large volume of the product to be controlled as well as to the inhomogenity of distribution of pathogens in the material only products processed in a validated process should be distributed to the consumer or user. This means that the following strategies must be combined with each other in order to assure hygienic safe utilization of the processed sludges

" Validation of treatment (disinfection by chemical, physical or biological means)

" Continuous registration of the relevant process parameters (e.g. temperature, pH-value, exposure time)

" Microbiological supervision of the final product (indicators)

" Restriction of the utilization of the final product. R. Böhm 55 Public health aspects connected with agricultural utilization of sewage sludge

HUMAN MEDICINES Domestic sewage

Sewage sludge

Se wage ef flu ent

VETERINARY Crops MEDICINES

Slurry Li vestock treatment excreted in faeces/urine Di rect exc retio n onto pasture Soil organisms

Li vestock treatments applied as dip or local application

Grassland inv erte brat es

Terrestrial vertebrate wildlife

Aq uat i c Fish farm medicines o rganisms

Micro organisms

Figure 2: Simplified diagram showing the relationship between medical product uses and environmental risk assessment schemes 56 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

The combination of certain restrictions in using sewage sludge as fertilizer and/or soil improver and the type of treatment used with a system of process validation and steady supervision of relevant process data as well as of the final product, as shown in Fig. 3., should provide reasonable protection for farmers, consumers and the environment against hygienic threats. Even if a list of approved treatment processes is available, the methods for the validation of the treatment procedures themselves must be elaborated on EU-level.

I II III PROCESS VALIDATION PROC ESS S UPERV ISION PRODUCT SUPERVISION of the treatment process Cont inuous recording of - Regulary supervision of total ly or in par t relevant pr ocess data e.g. the treated sludge or temperature, pH-value, fi nal pr od u ct concerningits reliability to inactivaterepresentative input-output - e.g. absen ce of test orga nisms Data must be filed for at Salmonella in 50 g l east 5 years

Figure 3: Process validation and supervision combined with product supervision in order to assure hygienic safety of sewage sludge and related products for use as fertilizer or soil improver

5 References

BÖHM, R., FINK; A., MARTENS, W., PHILIPP, W., WEBER, A., WINTER, D. (1997), Abschlußbericht zum Forschungsvorhaben 02-WA 9257/5 "Veterinär- und seuchenhygienische Untersuchungen zur Überprüfung von Gülleaufbereitungsverfahren und der erzeugten Gülleaufbereitungsprodukte", Insitut für Umwelt- und Tierhygiene, Universität Hohenheim, D-70593 Stuttgart

BÖHM, R., MARTENS, W., BITTIGHOFER, P.M. (1998): Aktuelle Bewertung der Luftkeimbelastung in Abfallbehandlungsanlagen. M.C. Baeza- Verlag, Witzenhausen

BREER, C. (1981): Freilandbiologie und Infektzyklen der Salmonellen. Schweiz. Arch. Tierheilk., 123, 89-96 R. Böhm 57 Public health aspects connected with agricultural utilization of sewage sludge

BÜRGER, H.-J., STOYE, M. (1978): Parasitological problems associated with recycling of animal excretions, pp 24-34. In: W.R. KELLY (ed.): Animal and human health hazards associated with the utilization of animal effluents. ECE- EUR 6009, Office for the official publications of the European Communities, Luxembourg

COULSON, J.C., BUTTERFIELD, J. and THOMAS, C. (1983): The herring gull Loras argentatos as a likely transmitting agent of Salmonella montevideo to sheep and cattle. J. Hyg. Camb. 91, 437-443

EDEL, W., GUINNEE, P.A.M., VAN SCHOTHORST, M. and KAMPELMACHER, E.H. (1972): The roll of effluents in the spread of salmonellae. Zbl. Bakt. Abt. Orig. A 221, 547-549

FOSTER, J.W., and SPECTOR, M.P. (1995): How Salmonella survive against the odds. Annu. Rev. Microbio., 49, 145-174

GRÜNER, C. (1996): Gesundheitszustand und Belastung von Beschäftigten im Abfallbereich. Erste Ergebnisse und Schlussfolgerungen für die Praxis, pp 315- 334. In: Biologische Abfallbehandlung III (Wiemer, K., Kern, M., Eds.), Baetza-Verlag, Witzenhausen

HEILMANN, G., HÖPKEN, W. und MÜHLENBERG, W. (1973): Salmonellen bei Lachmöwen - ein neues Problem für die Landwirtschaft. Gesh.Wes. Desinfektion 65, 145-147

HELLMANN, E. (1977): Latente Salmonellen-Infektionen der Tiere und ihre Ursachen. Wiener Tierärztl. Mschr., 64, 173-180

HICKEY, J.K.S. and REIST, P.L. (1975): Health Significans of Airborne Microorganisms from Wastewater Treatment Processes. Journal WPCF 47, 12, 2741-2773

HURST, C.J. (1989): Fate of viruses during wastewater sludge treatment processes. CRC Crit. Rev. Envir. Control, 18, 317-343

KÖHLER, B. (1993): Beispiele für die Anreicherung von Salmonellen in der Umwelt. Dtsch. tierärztl. Wschr., 100, 264-274 58 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

MAYR, A. (1983): Verbreitung von Infektionserregern über Abfälle durch Haus-, Gemeinde und Freilandungeziefer unter besonderer Berücksichtigung der Gesundheit des Menschen. Zbl. Bakt.Hyg., I. Abt. Orig. 1B, 178, 53-60

MENKE, G. (1992): Hygienische Aspekte der Bioabfallkompostierung. Teil 1: Phytohygiene, pp 68-73. In: Proc. Symposium des Umweltministeriums Baden- Württemberg und der LG-Stiftung "Natur und Umwelt", 26. März 1991 in Stuttgart, "Bioabfallkompostierung - Chance der Abfallverwertung oder Risiko der Bodenbelastung?". Stuttgart: LG-Stiftung "Natur und Umwelt", Königstr. 3- 5, D-70173 Stuttgart

METZLER, A., REGLI, W., LEISINGER, M., Heider, H., SCHWEIZER, K. und TABISCH, A. (1996): Viren und Parasiten im Trinkwasser: Risiken und Prävention. Mitt. Gebiete Lebensm.Hyg. 87, 55-72

MÜLLER, G. (1965): Die Salmonellen im Lebensraum einer Großstadt (Untersuchungen über Vorkommen und Lebensdauer in der Außenwelt). Beitr.Hyg. Epidemiol. 19, J. Ambrosius Barth Verlag, Leipzig

OTTOLENGHI, A.C. and HAMPARIAN, V.V. (1987): Multiyear study of sludge application to farmland: Prevalence of bacterial enteric pathogens and antibody status of farm families, Appl. Environ. Microbiol. 53, 5, 1118-1124

PAGON, S., SONNABEND, W. und KRECH, U. (1974): Epidemiologische Zusammenhänge zwischen menschlichen und tierischen Salmonella- Ausscheidern und deren Umwelt im schweizerischen Bodenseeraum. Zbl. Bakt. Abt. I Orig. B 158, 395-411

STRAUCH, D. (1991): Survival of pathogenic micro-organisms and parasites in excreta, manure and sewage sludge, Rev. Sci. Techn. Off. Int. Epiz. 10. 813-846

STRAUCH, D. (1998): Pathogenic micro-organisms in sludge. Anaerobic digestion and disinfection methods to make sludge usable as fertiliser. European Water Management 2, No. 2, 12-26

TSCHÄPE, H. (1996): Die Verbreitung antibiotikaresistenter Keime in der Umwelt mit besonderer Beachtung der Salmonellen. Dtsch. tierärztl. Wschr. 103, 273-277 R. Böhm 59 Public health aspects connected with agricultural utilization of sewage sludge

WILLIAMS, B.M., RICHARDS, D.W., STEPHENS, D.P., and GRIFFITHS, T. (1977): The transmission of S. livingslone to cattle by the herring gull (Larus argentatus). Vet. Rec. 100, 450-451

WUTHE, H.H. (1973): Salmonellen in einer Brutkolonie von Lachmöven. Berl. Münch. Tierärztl. Wschr. 86, 255-256

Author: Prof. Dr. Reinhard Böhm Universität Hohenheim, Institut für Umwelt und Tierhygiene sowie Tiermedizin mit Tierklinik –460- D-70593 Stuttgart 60 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna 61 Wiener Mitteilungen (2001) Band 171, 61-76 Copyright © 2001; Institut für Wassergüte / TU-Wien

Marketing of sludge and quality assurance

T. Evans Stonecroft, England

Abstract: This paper discusses the importance of quality assurance and of marketing in achieving sustainable and reliable solutions for the use or disposal of sewage sludge. These considerations are equally applicable to other biomaterials, for example composted biowaste or animal manures. The author’s experience has been that it is impossible to be confident in the consistency of operations unless there is quality assurance (QA). An organisation that is not confident in the consistency of operations may be vulnerable to causing harm, to legal and financial liability and to loss of reputation. The paper also recommends complementing QA with HACCP (Hazard Analysis and Critical Control Point) which it recommends is a better way to design processes in order to achieve sustainable and reliable outputs. Stakeholder acceptance is essential to the longevity of strategies for the use or disposal sludges and other biomaterials. The paper discusses the advantages of looking at the situation from the stakeholders’ perspectives and of communicating with them, which is the essence of marketing.

Keywords: Biosolids, Branding, Environmental liability, HACCP, Marketing, Quality assurance, Sustainability

1 Introduction

Applying the principles of marketing and of quality assurance are important components of achieving sustainable and reliable solutions for the use or disposal of sewage sludge. But this is equally true for any business. The definition of sustainability that I think is appropriate is “Actions today that do not compromise the freedom of action of future generations”. Like all other definitions of sustainability this one is open to debate but sustainable development does not mean no-change. Human activity has changed the 62 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna landscape over millennia. Some of the landscape features that we treasure today are entirely the product of human intervention and activity.

Sewage sludge is an inevitable consequence of treating wastewater. We can change the form and quantity but it is impossible to entirely eliminate a solids- rich residual, even if this is ash. This residual has to be managed properly otherwise the wastewater treatment performance will be compromised. Recovered water is another product of wastewater treatment, and its composition is usually the subject of legally binding restrictions.

Quality assurance (QA) brought a revolution to manufacturing industry in terms of increasing product reliability. In general those that did not apply QA found themselves at a competitive disadvantage because customers wanted the greater reliability that QA enabled. The exceptions were those who created a cachet attached to their products which meant that people were prepared to tolerate a lack of reliability for the prestige of owning one of their products. However customers still prefer greater reliability and longevity even from these up- market products. Creating a brand image that makes people overlook, or tolerate, certain imperfections is the product of good marketing and/or good luck. But it is not likely to apply to sewage sludge.

Wastewater treatment is subject to legal obligations, for example, the recovered water must not exceed certain limits (e.g. SS, BOD, NH4, P), health and safety obligations to employees, etc. If the sludge is to be used on land it is subject to limits and if it is burnt the emissions must not exceed limits. QA enables process steps to be performed consistently in order to achieve the intended results. Whilst operators can take justifiable pride in consistently achieving their regulated limits, the public is less inclined to celebrate this success because there is an assumption that reputable organisations operate within the law, so there are no prizes for not breaking the law. Figure 1 shows the journey to sustainability as represented by the DuPont chemical company. DuPont places Compliance [with legal obligations] at the beginning of the journey because, as discussed above, it is a “given”, i.e. it is expected that the business will not break the law. T. Evans 63 Marketing of sludge and quality assurance

Sustainability Inherently Safer Products & Processes B u Clean Greater Stewardship- Technology s Less Material i Renewable n Resource Resources e Efficiency s s Goal Is Zero V a Public Trust l u Compliance e Business, Safety, Health, Environment Integration

Figure 1 The journey to sustainability (Wika, 1998)

Building Public trust is also regarded as a foundation step on the road to sustainability. DuPont is not merely altruistic in having set a company goal of sustainability. It appreciates that a business that is not sustainable has a limited future. It has also found that applying the model increased shareholder return by 400% and decreased injury, illness, incidents, waste & emissions by 60% at a time when raw material & energy consumption increased by 40% because of increased output. This model has great relevance to the matter of using and disposing sewage sludge.

Odour is a good example of the weakness of just meeting the requirements of regulations. The 1986 EU Sludge Directive (CEC, 1986) does not mention odour and neither does the federal regulation in the USA (USEPA, 1993). But most people with practical experience know that odour can generate more public reaction than anything else. In the USA many counties (sub-divisions of States) have passed ordinances restricting or banning the use of biosolids because of public opposition created by odour from biosolids-application. The biosolids complied with the federal and State regulations, but they stank. Looking at the question of odour dispassionately, it is very doubtful whether any amount of public-acceptance work could persuade people that they should tolerate the odour. Therefore public trust necessitates treating the biosolids so that they are not offensive, especially when spread. 64 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

2 Quality assurance

The principle of QA is to harmonise the way that each step in a process is performed in order that it is performed the same way throughout the coverage of the programme and by every individual, be they experienced or a new recruit to the job. Figure 2 illustrates the QA cycle. After deciding the Scope of the scheme, a Procedure is designed for each step in the process; it is then tested to check that it is practicable before it is put into operation. Performance is monitored and if weaknesses or areas for improvement are found the Procedure is re-designed and the cycle starts again.

design

monitor test

operate

Figure 2 The Quality Assurance cycle

One of the features of QA is that actions are recorded so that they can be verified and traced. Some criticise QA for being cumbersome and generating paperwork.

I was introduced to QA in 1989 when I was running a biosolids (treated sewage sludge) recycling programme for about 2.5 million population equivalent. This was subsequently adopted as the business model for the whole of Thames Water’s biosolids programme and it increased to 6.5 million p.e. This operates in the southeast of England, around London, which is the most populous area of the country.

Everybody in the team thought they were doing the job properly and were complying with all of the legal obligations, but when we examined it, everybody was doing things differently. As examples we all knew that we T. Evans 65 Marketing of sludge and quality assurance should leave an untreated margin around private wells, explain to farmers what they could grow on treated fields and find out if there were any pre-existing crop or veterinary problems, but when we examined activities it was seldom possible to prove that every one the necessary things had been done. This obviously meant that the company was vulnerable. The company could have suffered financial liability and/or damage to the reputation of the biosolids programme. By early 1993 we had QA accreditation for our biosolids programme and were receiving biosolids from treatment processes that were also quality assured. We built to a position of consistently achieving 100% compliance measured by an independent team.

The last thing that I wanted when I was running such a large operation was that somebody else would claim to have found an adverse effect of which I had no prior knowledge. Due diligence studies into the effects of using biosolids were therefore part of the programme. If there was an adverse effect of which we had been unaware I considered it better to know about it as soon as possible in order that corrective action could be taken if that were possible, or the strategy could be changed before damage was done if that was necessary. We found no emerging issues that gave us cause to contemplate changing our strategy radically. Continuous improvement became part of the culture.

3 HACCP

QA will assure that operations are performed in a consistent, traceable manner. HACCP (Hazard Analysis and Critical Control Point) is a very useful complement to QA when it is applied to the design of the process. HACCP was developed in the 1960s to improve the confidence in the safety of food supplied to astronauts for the USA’s manned space-flight programme. Prior to HACCP there had been reliance on “end-of-pipe” testing, but it was realized that this only told you that the sample you tested was acceptable. You did not know about the material that had not been tested, i.e. the food that was going to be sent into space because it had not been tested. HACCP has been adopted by the United Nation’s Codex Alimentarius Commission and Food & Agriculture Organisation / World Health Organisation Food Standards Program (Codex, 1997) and by national governments. Today HACCP is the basis of food safety 66 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna and has also been adopted by some non-food industries, but it is not yet widely recognised by the water industry.

HACCP has become the core of biosolids management in the UK as a result of discussions with the food industry, by whom it is known and trusted; that means we are speaking the same language. But the benefits go much deeper than semantics and building confidence in a major stakeholder. Important though that is, I think it is actually a better way to design the management of a process.

The first step in HACCP is to decide what you are producing and the intended uses of the product (for example, biosolids that will be used to fertilise soil for growing a range of crops) and then determine the associated hazards. They might include metals, organics, pathogens, odour, public hostility, litter, water pollution, prosecution for non-compliance, etc. Using a decision tree (Figure 3) you then look at each step in the production process to see whether it is capable of bringing the risk from any of the hazards associated with the product to acceptable levels. If the process step is capable of controlling the risk it is a Critical Control Point (CCP) for that risk, unless there is possibility of unacceptable re-contamination further down the process. The minimum operating conditions (capable of controlling the risk) are the Critical Limits (CL) of the CCP. Thus if every part of the production goes through the CCP, and if the CCP continuously operates within its CL, you know the risk is controlled. CCPs have to be monitored and the results recorded; these records are the proof of satisfactory control. End-of-pipe testing is then merely used to verify that the CCP is operating and the CL are appropriate. Another element of HACCP is defining Corrective Actions – what do you do when the CL or verification go out of range? The requirement to define Corrective Actions is a very important feature because it forces you to plan for the downside. T. Evans 67 Marketing of sludge and quality assurance

Modify steps in process or product

Q1 Do preventative control measures exist? Yes No Is control at this step necessary for No Not a CCP STOP1 safety? Yes

Is the step specifically designed to eliminate or Q2 reduce the likely Yes occurrence of a hazard to an acceptable level?

Could contamination with identified hazard(s) occur in excess of acceptable Q3 Not a CCP STOP level(s) or could these No increase to unacceptable levels?

Yes

Will a subsequent step eliminate identified Critical Control Point Q4 hazard(s) or reduce likely No occurrence to acceptable CCP level(s)?

1 Proceed to next identified hazard in the described process Yes Not a CCP STOP1 2 Acceptasble and unacceptable levels need to be determined within the overall objectives in identifying the CCPs of the HACCP plans

Figure 3 HACCP decision tree

HACCP is complementary to QA; it is not an alternative. HACCP comes first because it is the tool to design the process; QA standardises the operating procedures. People coming from a tradition of regulation often (wrongly) resist defining CCPs because they think of them as points of regulation whereas they should regard CCPs as a defence because they demonstrate due diligence. It takes some time (and help) to get into the HACCP way of thinking; to get full value the facilitator should understand the biosolids business. HACCP enables innovation. It is proactive, verifiable, and focuses resources where they are needed. It creates solutions that are appropriate to each individual situation. 68 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

This is in marked contrast to prescriptive regulation, which is very unlikely to anticipate every possible local variation and peculiarity.

If I were running a biosolids programme today, I would welcome HACCP with its systematic approach to hazard identification and risk control, because it is a better way to design the process. Of course, HACCP can’t help to control hazards that you don’t identify so it is important to be honest and dispassionate. The last thing a biosolids programme needs is a hostile front-page news story.

HACCP can be applied to the whole biosolids process, from control of pollutants at the source through biosolids treatment to land-application. It can increase the confidence of producers, users, and stakeholders, and thus help to assure longevity to a biosolids programme.

HACCP was introduced to the water industry in the UK during discussions with the British Retail Consortium (BRC). The BRC represented all of the food industry trade associations in discussions with the water industry about the efficacy of using biosolids on land. The discussions led to an agreement on how biosolids should be treated, applied and used in farming (ADAS, 1999). This agreement was not the destination of the journey to sustainable use, much work is continuing, but it was a very significant milestone.

Sometimes people suggest there should be a de minimus limit below which QA (and HACCP) is an unwarranted burden. The case of Walkerton in rural southern Ontario, Canada demonstrates the error of such a suggestion. Walkerton is a small town with 4900 residents. In May 2000 it was struck by infection of E. coli O157:H7. Seven people died and 2,300 became violently ill. The town water supply comes from 3 wells; the chlorine dosing equipment was poorly maintained. One of the wells was not sealed to the rock around the shaft, and it was downhill from a small, cattle farm. The ground was swampy and the aquifer below was covered by only 2.4 metres of sand, gravel and rock - not enough to filter out bacteria before water reached the well. Another well was artesian and had a very weak overflow flap valve. The laboratory had repeatedly reported bacterial contamination of Walkerton’s water. In May 2000 there was heavy rain, which caused run-off from local farmland. Run-off water got into the wells, the chlorine dosing was not working properly [again] the water superintendent put the lab’s report of failing water aside [again] thinking he could solve the problem and E. coli O157:H7 was pumped into pumped into T. Evans 69 Marketing of sludge and quality assurance the town’s water supply with disastrous consequences. HACCP and QA would have prevented this tragedy of errors. My local village butcher’s shop is required to have HACCP, can there really be a valid argument for exempting a facility producing biosolids for use on land?

4 Marketing

If a man ...... make a better mousetrap than his neighbour, ...... the world will make a beaten path to his door.” Ralph Waldo Emerson

Emerson might be correct, but if the man has a production line continuously producing large numbers of these super mousetraps it is necessary to tell the world that they exist and how wonderful they are. Otherwise there will be a mountain of mousetraps before a market for them spontaneously generates. That’s the situation for the recyclers of biomaterials.

Merely by saying that the mousetraps carry the EU’s СЄ safety mark won’t create the market. Public and stakeholder confidence is not created by regulatory limits. The public assumes that regulatory limits are safety thresholds; that’s if they trust the government policy makers. Ratcheting down limits does not increase confidence, it merely brings the whole process into question, because it is seen as a demonstration that the policy makers were wrong the first time. As DuPont showed in their model (Figure 1) Compliance is a given.

To create a market the producer is well-advised to understand what potential customers want and then produce something that has the features, benefits and price that will induce customers to purchase. If a new product is going to be a substitute for existing products in an established market, success can be achieved by establishing a better position on the Cost-Quality-Price triangle (Figure 4). However success can also be achieved through better positioning so that there is better awareness of the product. 70 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

Price

Cost Quality

Figure 4 The Cost, Quality, Price triangle

Markets can also be created for products that people do not know that they want. For example there is now a huge market for bottled water, even where the quality of tap water is perfectly acceptable, there has been no history of buying bottled water and where tap water beats bottled water in blind tastings.

Marketing can be defined as the identification of customer needs and their satisfaction at a profit – in the case of biomaterials this could be at least cost. One can consider three classifications of organisation depending on their orientation:

S A marketing orientation involves identifying customers’ (and stakeholders’) needs

S A product orientation focuses on making products and expecting people to buy them,

S A selling orientation stresses aggressive selling to move [dispose] the product

My experience has been that marketing and a good brand can be very valuable for biosolids recycling. Market research showed that farmers wanted the physical properties and fertility of their soils improved. They wanted their gateways, farm roads, etc. respected and they did not want aggravation from neighbours about odour or vehicle nuisance. They wanted to be able to predict the amount of complementary fertiliser needed to give optimum yields with confidence. They also wanted to be confident that by having their land treated with biosolids they would not compromise the saleability to of their produce, or T. Evans 71 Marketing of sludge and quality assurance the capital value of their land. The agreement with the food industry (ADAS, 1999) has been vital in answering the question about saleability of produce. In order that we could be sure that biosolids were only used on land that we had sampled and approved we applied the biosolids. Therefore farmers did not have to handle the biosolids and they were not concerned about the physical form in which they were applied, provided application was even.

By field experiments we were able to benchmark the fertiliser replacement value of our different types of biosolids into the established models for mineral fertilisers. This enabled confident communication of fertiliser-replacement information in language that farmers and agronomists understood. The work of delivery and application was undertaken by contractors but the Specification to which they worked required even, monitored application and reinstatement of any damage. This was encapsulated in a strong brand and readily identifiable livery. But the brand was only applied to an operation when it attained the required levels of quality.

Market research had showed that farmers wanted to be confident that by having their land treated with biosolids they were not going to jeopardise the saleability of their produce, or the capital value of their land. The food industry in the UK is very integrated with more than 60% of food being sold by 4 retailers. In order to protect their brands and reputations, they tell farmers how they want crops grown that they will buy. Thus the food industry has become a very powerful surrogate buyer of agricultural inputs, including biosolids. The logical step was to find out what these stakeholders wanted, to learn about their business drivers and to explain our business – in other words, market research. Neither party understood the other’s business. After we had discussed the science and the controls associated with using biosolids on land the food industry representatives acknowledged that the management of chemical hazards was adequate. However they had residual concern about biological hazards. The process conditions, cropping restrictions and barrier controls had been designed in the 1980s, but since that time food related illness had increased enormously, responsibility for food safety had been placed on all parts of the production and distribution chain and new organisms had emerged. The food industry representatives queried whether practices that were good enough in the mid- 1980s were still appropriate at the end of the 1990s. To bridge this gap the water industry changed sludge treatment, cropping restrictions and biosolids 72 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna application methods voluntarily as a precaution and initiated jointly steered research into pathogen die-off during treatment in order that risk could be assessed objectively. Part of marketing is finding out what customers want. Finding out what these surrogate customers wanted led to an agreement between the food industry and the biosolids producers (ADAS, 1999).

In the case of the landowners they were concerned about possible long-term impact, gradual pollution and emergence of some factor of which we are not currently aware. The likelihood of an emergent risk seems pretty small, given the amount of research into the effects of biosolids and the huge improvement in quality over recent years. But it is hard to refute the theoretical possibility or the challenge that scientists had not predicted DDT, asbestos, etc. so how can we know there will not be a new issue. In this case the customers wanted indemnity. Indemnity seems reasonable if biosolids producers believe that their activity is sustainable. In this case one of the largest underwriters offered an insurance solution to biosolids producers that were prepared to base the biosolids processes on the principles of HACCP and to have independently audited QA. The offer was strict-liability insurance against latent-defects emerging in 25 years following an application; it would be transferable to a new owner if the land were sold. The European Commission’s considerations on environmental liability (CEC, 2000) are likely to make such insurance a more common feature of business.

5 Branding

A brand can encapsulate the whole experience of a product. Brands can be very valuable. They need to be created with care and maintained. If the brand-values are diluted the product can become devalued. Similarly a brand, which had once appeared to be impregnable, can become discredited if an organisation loses its vision.

Brands can also be very motivational for those within an organisation because, if they believe in the brand, it gives them a common identity. It has been said that a brand should run though the whole organisation like the letters through a stick of rock, or the marzipan through a loaf of stollen. T. Evans 73 Marketing of sludge and quality assurance

Whether or not you like their products and methods, the McDonald’s and Coca- Cola brands have global success because when customers see the brand they are confident in the experience that they are going to receive. QA is fundamental to achieving this consistency of product wherever in the world it has been cooked or bottled.

Branding enabled us to differentiate our quality assured biosolids operation from competitors offering other biomaterials (brewery waste, papermill sludge, cess and septic waste, etc.). Agronomists advised their clients that they should use TERRA ECO·SYSTEMS and the fertiliser advice we gave because it would increase their profit. However they advised against accepting other biomaterials because their quality and application were inconsistent and unpredictable and therefore they [the agronomists] could not advise on how to farm the treated land. The following conversation between two farmers was relayed to me:

Farmer 1: “Are you going to have sludge on your land?”

Farmer 2: “No, but I’m going to give that TERRA a try, it looks like pretty good stuff.”

This differentiation was achieved through researching customers’ needs, understanding (and communicating) the features and benefits of our products and by unremitting pursuit of quality – clean trucks and workwear, well maintained equipment, rapid reinstatement of any damage, etc.

Developing appropriate Specifications for the work, and being prepared to pay an appropriate rate for the work were essential parts of attaining this high quality. Before 1992 there were contracts with lower rates and lower quality. They were losing customers, alienating communities and bringing Thames Water and its sludge into disrepute. That was why the decision was taken in 1992 to apply the TERRA model was to all the biosolids operations. As each operation attained the quality and values it was brought into the brand.

One of my wastewater treatment sites composted dewatered sewage sludge with straw, after maturation the product was very well stabilised and met the most rigorous pathogen requirements (Lasiridi et al.). Since the 1980s there has been intensive campaigning in Britain against the extraction of peat for horticultural purposes because there is a limited area of lowland raised bogs in GB and they 74 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna have significant ecological value. The campaign included regular references on prime-time television gardening programmes so that there was a high level of public awareness. In 1993 I trialed a range of formulations and found it was technically feasible to make peat-free growing media based on the composted sludge that performed as well as the brand-leading media (Evans & Rainbow, 1998). Subsequently our market research showed that 35% of gardeners had tried peat-alternatives but all found them inferior to peat-based media, which was why peat-alternatives had established <5% market share. Gardeners said they would like to use peat-alternatives provided they performed as well as the brand-leading media and were similarly priced. They were not worried that we were considering offering sewage-derived materials. To make sure there was no room for misunderstanding bags and point of sale signs are clearly labelled “based on sewage cake sanitised by composting with straw”. After a 3-year development programme we had a range of technically proficient products in bags with attractive designs (again supported by market research). The brand had established recognition in southeast England because of the trucks delivering to farms. The quality was consistent (because of QA) and we set the prices to match the brand-leaders. We launched at the major national gardening trade show in September 1996 and to an extent relied on Emerson’s dictum. The market did grow but we had underestimated the need to tell retailers about the products and why they should stock them. However by devoting more effort to selling we established nationwide distribution in the first year and a trebling of sales year-on-year. Hobby gardeners and professional growers became very loyal to the products, because they performed very well. There was not one question about the heavy metal content, etc.; the question simply was not relevant to the customers.

6 Conclusion

The answers to achieving sustainable and reliable solutions to the use or disposal of sewage sludge and other biomaterials are the same as for any other business. Installing the appropriate technology is only part of the answer. It has to be operated so as to give consistent quality and the solution must be acceptable to the customers and the stakeholders. Thus, quality assurance and marketing are essential components of achieving sustainability. Quality T. Evans 75 Marketing of sludge and quality assurance assurance for assuring that the outputs of the process comply with standards, regulations and customers’ and stakeholders’ expectations and marketing for communication with customers and stakeholders. This communication means talking with customers and stakeholders, listening to what they have to say, and if there is a gap, discussing a strategy to close it. Most industries spend huge amounts of money and resources researching people’s attitudes and telling them about their products. Is it surprising that myths about the dangers of sludge use or disposal persist when the industry invests so little in communication?

7 References

ADAS (1999) The safe sludge matrix – guidelines for the application of sewage sludge to agricultural land. BRC, Water UK, ADAS

CEC (1986) Commission of the European Communities (1986) Council Directive of 12 June 1986 on the protection of the environment, and in particular of the soil, when sewage sludge is used in agriculture (86/278/EEC). Official Journal of the European Communities, No L181/6-12.

CEC (2000) White Paper on Environmental Liability COM(2000) 66 final Brussels 9 February 2000

Codex (1997) Basic Texts On Food Hygiene Codex Alimentarius, June 1997

Evans T.; Rainbow A. (1998). Wastewater biosolids to garden centre products via composting. Acta Horticulturae no 469, 157-168.

Lasaridi, K.E.; Stentiford, E.I.; Evans, T. 1999 Windrow composting of wastewater biosolids: process performance and product stability assessment. IWA conference “Disposal and utilisation of sewage sludge: treatment methods and application modalities” 13-15 October 1999, Athens

USEPA (1993). Standards for the Use and Disposal of Sewage Sludge. 40 CFR Part 503. Federal Register 58 (32), 9248-9415. (19 February 1993). 76 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

Wika, D. G. The journey to sustainability. IAWQ International Symposium on Management and Operation of Environmental Control Systems in the Chemical and Petrochemical Industry, Salvador, Brazil November 1998

Author: Dr Tim Evans TIM EVANS ENVIRONMENT Stonecroft, Park Lane, Ashtead, Surrey, KT21 1EU, England tel/fax: 00 44 1372 272 172 email: [email protected] 77 Wiener Mitteilungen (2001) Band 171, 77-88 Copyright © 2001; Institut für Wassergüte / TU-Wien

The sociological and economic challenges in using wastewater sludge as fertiliser for food production in France

Olivier Borraz Centre de Sociologie des Organisations, France

A recent study by consulting firm Arthur Andersen regarding the situation of sewage sludge recycling in Europe (and some other industrial countries) outlined a general tendency throughout Europe as to how the question was put on the agenda, tackled and solved. Not surprisingly, the Nordic countries were the first to react at the turn of the 1990s while the countries bordering the Mediterranean were not yet officially confronted with the problem, i.e. the question had not yet reached the political agenda. According to the study, a similar pattern emerged, in which the issue : gained access to the public sphere through a controversy over the sanitary risks related to the use of sludge in agriculture ; mobilized representatives from agriculture, the food industry and the wastewater treatment industry ; forced public officials to react ; which they did through the adoption of stricter regulation.

In this trend, France occupied an intermediate position, confronted with a crisis that countries situated north has already solved (Holland, Sweden, Germany, Finland and Denmark ; the only exception being Great-Britain) while the countries of the south were expected to encounter the issue soon. Unfortunately, if France has followed the above mentioned steps and has adopted stricter regulation, it has not yet come to term with the difficulties surrounding the use of sludge in agriculture.

Nonetheless, the study by Arthur Andersen underpins an important dimension regarding sewage sludge recycling : this issue is strongly linked to economic, political and regulatory trends throughout Europe. The emergence of the issue in any one of the countries mentioned is often related to national regulation 78 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna concerning food production standards in other European countries (such was the case with wheat produced by French farmers which could not be sold to German industrials, or canned vegetables for the Nordic markets). It is also related to European regulation regarding the use of sludge in agriculture (the 1986 council directive). Furthermore, countries follow closely their neighbours’ policies in the field of environmental and food security (not only for competitive reasons) since a gap between national regulations can have various consequences (e.g. the exportation of sludge toward countries with less severe regulation). Finally, one must not discard the fact that debates over sludge in some countries and the public decisions which follow can foster controversy in neighbouring countries. In summing up, the issue of sludge recycling has a strong European dimension.

Yet, this issue is also and maybe foremost embedded in a national context ; we shall see further down that in the case of France, this in turn refers to a local context as well. This embededdness can be observed through the processes by which the issue is put on the agenda, the procedures adopted to find a solution, the decisions that are taken and their implementation. Hence, it is difficult to apply the same framework of analysis to different national configurations. Furthermore, the debates over the use of sludge in agriculture reveal major transformations taking place in the different national economic sectors ; in the case of France : water industry, agriculture, food production and retailers. Finally, political institutions are also solicited : in France, an intricate institutional framework is undergoing deep changes, in the aftermath of decentralization reforms and under pressure from the European Union. The debate over sludge recycling in agriculture interferes with all these elements.

Stressing the strong national dimension underlying the debates and negotiations over the use of sludge in agriculture is not meant to deny the impact of the European factors mentioned above. It is destined to push forward the idea that solutions to the recycling of sewage sludge can only be national, and in the case of France essentially local, but that in order for these solutions to be implemented successfully, European regulation (as well as national regulation where local solutions are at stake) must take into consideration the particular nature of sludge and the fact that subsidiarity is called for in finding stable solutions. Olivier Borraz 79 The sociological and economic challenges in using wastewater sludge as fertiliser for food production in France

I will begin by analysing the French situation and more precisely I will point out the elements that stand in the way of a national agreement on the issue. I will then try to isolate what makes for the particular nature of sludge and in so doing suggest some solutions in terms of participatory procedures.

A long and quiet crisis

The controversies in France over the use of sewage sludge in agriculture date back to the early 1990s. Staged at the local level, they were for the most part due to problems of odours and in the east of France the importation of German sludge. The issue rose to national status in 1997, precisely when new and tougher regulation was issued. This paradox can be explained by the fact that between the moment the ministry of environment decided to write a new décret and the moment it was published, several events had occurred : the first mad cow crisis, the debate over genetically modified organisms, the renegotiation of the common agricultural policy.

The first event served as a matrix for subsequent food safety crisis, building on the previous blood scandal to promote health security as a major theme on the political agenda. More precisely, the mad cow crisis suggested that the introduction of foreign (i.e. outside, non natural) ingredients in the food production chain was a major source of danger. Sludge was rapidly compared to animal feed produced with animal by-products : the fact that there was nothing “natural” in using it to produce food and the vested financial interests served to stigmatise sludge recycling in agriculture.

The second event entertained the confusion between health and environmental risks. As in the case of sewage sludge, what was initially and fundamentally an environmental issue became a problem of health risk, the two dimensions being difficult to set apart. But the GMO debate also gave the opportunity to transfer the responsibility for health and environmental risks from the farmers to their suppliers (or in other circumstances to their buyers). Farmers were no more the culprits in damaging the environment (water pollution) and poisoning consumers (ESB) : they were now the victims of those who supplied them with dangerous products without giving them the necessary information or in some case forcing them to use it ; and in general under the domination of powerful 80 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna financial interests (suppliers or retailers) imposing drastic conditions on the food production process. This gave them a new and even stronger position in negotiating the use of sludge in agriculture, calling for witness public opinion.

Finally, the third event revealed the growing tensions among the representatives of French farmers. While on the one hand, the largest federation of farmers’ unions (FNSEA) opposed the new common agricultural policy, the wheat (corn in G-B), corn (maize in G-B) and beet producers were (successfully) negotiating directly with Brussels, bypassing both the FNSEA and the French ministry of agriculture in order to obtain special conditions. This division between the big farmers on the one hand (and also the richest, those who contribute the most to the French trade balance and who sell their products on international markets) and the FNSEA on the other (more interested in preserving a productive model built up from the 1960s on, in close relation with the ministry of agriculture, and careful to represent the interests of farmers in their diversity, notably in terms of size) manifested itself quite clearly in the case of sludge. While the FNSEA took an active part in writing the new regulation on the use of sludge in agriculture (which it approved but wanted to use as a bargaining advantage to negotiate less severe regulation on more important issues, namely water pollution), the wheat, corn and beet producers took position against this use, arguing that their foreign buyers did not want products grown on soil having received sludge (or at least imposing stricter measures on the use of sludge), that the mad cow crisis should serve as a warning of what public opinion is not ready to accept any more, and that the new regulation left many questions unanswered as to the risks related to sludge used in agriculture (thus indirectly accusing the FNSEA of having badly defended farmer interests).

By their attacks, the wheat, corn and beet producers opened a controversy at the national level which had two major consequences : the new regulation published end of 1997 lost most of its credibility and effectiveness ; a national roundtable with all the different stakeholders was organized early 1998 to bring back public trust in this issue. Two years later, after much discussion and the production of various studies and reports, the debate was suspended. Yet no national agreement has been reached – even though three ministers in July 2000 openly called for the development of sludge recycling in agriculture as the best available solution for disposing of sludge. Olivier Borraz 81 The sociological and economic challenges in using wastewater sludge as fertiliser for food production in France

Failure to reach a national agreement can be accounted for by the fact that the themes around which the negotiations were undertaken were imposed by the representatives of the farmers’ unions, namely : protecting the farmer’s main working tool (land) from any ban or loss of value due to sludge recycling ; getting official recognition by society that farmers taking sludge were doing society a favour ; demanding a special fund in case the use of sludge proved to be dangerous (in the light of new scientific evidence) or harmful to the crops.

The fact that these themes were central in the negotiations is directly related to the power wielded by the farmers’ unions in France, their strong and ancient ties with the ministry of agriculture and their capacity to negotiate with public officials. But it had two consequences.

- These themes exacerbated oppositions among the participants and made it difficult to reach an agreement. In particular, the representatives of local elected officials as well as consumer associations refused a special fund, arguing that there was no reason why such a fund should be created (it would set a precedent) and that it would have an impact on the water bill (on which wastewater treatment is financed). They were simply not ready to satisfy farmers so easily with such a symbolic measure and no guarantee that farmers would keep taking sludge. They were helped by the ministry of finance who, in order to protect the insurance companies from unfair competition and fearful of any innovation that could serve as a precedent, blocked the idea of a fund and argued that insurance companies could very well do the job. Simultaneously, the landowners demanded that they be asked to give their authorisation before a farmer renting his land received any sludge. This was considered by other participants as unacceptable, since it would give the landowners an influence they have been losing regularly since the 1960s, due to the efforts of the FNSEA to protect farmers against their landowners. But since landowners were a major ally of the FNSEA in demanding a fund, the latter had to work out a compromise since landowners firmly opposed any agreement leaving their demands unsatisfied.

- Major issues related to sludge recycling in agriculture were left aside, notably the local dimension on the one hand and the health risks and the attitude of the food industry and big retailers on the other hand. 82 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

The reasons for which local associations and individuals opposed sludge recycling in agriculture, namely odours and various inconveniences due to the transport and spreading of sludge, were not discussed at the national level. More generally, the debates, discussions and negotiations referred only marginally to local factors, the difficulties encountered by professionals in sludge recycling, local administrations, farmers, or the solutions found locally to build trust and stability around this issue. For instance, if the debate over the institution of a special fund occupied in the national roundtable much of the participants’ time and energy, it would have had little impact on the decision taken by farmers at the local level ; those that refused to take sludge did so on a basis which could not be altered by a fund : either they were under strong pressure from their immediate environment or they had received precise indications from their buyers. The fund would not change this situation.

Even though health risks and the attitude of the food industry and big retailers accounted for most of the refusal by farmers or the different actors along the food production chain to accept the use of sludge in agriculture, they were marginal in negotiations at the national level. When it became apparent that a national agreement would not be reached, the blame for the difficulties encountered in recycling sludge was put on retailers and the food industry, accused of acting solely for marketing motives, but no effort was made to negotiate with them, let alone attempt to understand their positions on the issue. Yet it was apparent that their decisions were not taken on the basis of any risk assessment but simply on the basis of previous crisis (ESB, listeria, dioxine, Coca Cola) which had had strong financial implications : hence, they were simply anticipating a new crisis, this time around sludge (which, if it occupied so many people in debating over the risks and gave rise to so many discussions, carried high economic risks). More generally, most of the discussions and negotiations in the national roundtable were concerned with the risk for the environment (taken as a productive resource for the farmers) and only addressed the health risks as a minor objection that could easily be overridden.

In summing up, not only was it difficult to reach an agreement, given the oppositions among the participants to the roundtable and the diversity of their Olivier Borraz 83 The sociological and economic challenges in using wastewater sludge as fertiliser for food production in France interests, but had it been reached, it would not have answered the basic reasons for which more and more farmers were refusing to use sludge on their land. In other words, further actions would still have to be taken. But by failing to reach an agreement, participants in the roundtable comforted those that expressed doubts regarding sludge recycling : there must be a problem, else why didn’t they agree ?

It must be noted that the disagreements were not on health or environmental risks. Among all the participants, there was a general agreement that the use of sludge in agriculture, if it abided by regulation, carried no risks (at least on the basis of present scientific facts) and that it was probably the best way (both from an ecological and an economic point on view) to eliminate this residue. The large quantity of research on the subject of sludge recycling and its impacts on soil and crops, both in European and French research programs going back to the early 1970s, as well as the experience accumulated in sludge recycling beginning in the mid-1970s, were determining elements in achieving this agreement : there was simply no indicators of risk available and more important no accidents that could be directly imputed to sludge recycling in agriculture (the only referenced case, that of a mare in Normandy, being much debated). Documents reflecting this consensus, both on scientific and technical data, were published by participants to the roundtable in order to inform all those concerned.

Nonetheless, it proved impossible to achieve consensus around the ways and means to organise the use of sludge in agriculture : this is an issue which is fundamentally local in nature and which holds too many different meanings for the different stakeholders.

Coming to terms with sludge recycling

The essence of the roundtable organised at the national level was to put all the different stakeholders together and to get them to come to an agreement. This proved impossible for reasons already mentioned but more fundamentally because the issue of sludge is not one easily agreed upon and because its elimination in France is primarily a local problem. 84 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

Sludge holds different meanings, conveys different representations and carries different values for the stakeholders. It can be seen as waste, a dangerous material, a fertiliser, an industrial by-product, a new source of expenses, a financial risk or an opportunity to negotiate on other issues. While some express doubts over the heavy metals found in sludge, others prefer to worry about the organic compounds or the micro-organisms. For some it must remain free for the farmer using it while others insist on the fact that it has, even in that case, a financial value. If some participants in the roundtable had a clear idea as to what sludge exactly was, others simply did not know at the start and yet had to define a position.

In these circumstances, it proved very difficult to obtain a single unified representation, let alone an agreement as to how sludge should be recycled and how that should be financed. Such was not the case at the local level, where agreements seemed easier to come by – even though they remain rare.

First of all, sludge disposal is a real and very concrete problem to solve for local actors – in contrast with the discussions in the national roundtable. Figures and scientific data given at the national level give a very approximate picture of the nature of the problem at the local level : they tend to agglomerate facts highly diverse in their meaning and value. In other words, they build an artefact – the national problem of sludge disposal in France – which has little in common with the way the problem is defined and addressed at the local level. The important diversity in sludge composition, in conditions of treatment and storage, in land- use, in types of culture, in climate and types of soil, etc. simply does not fit with the idea that there is a single problem to solve at the national level. This did not help participants in the national roundtable in grasping the exact nature of the problem – in contrast with local actors who can easily understand what is at stake and the consequences of a general disagreement.

This does not mean that representations and meanings easily converge locally. Quite the contrary : sludge is a problem common to worlds that largely ignore each other. It is not the same problem for each of them, yet they have to find a solution which requires they get to know and understand each other better. For example, the social distance between farmers and urbanites recently installed in a (former) rural setting is immense, and it is often the latter that protest against the smell of sludge spread by the former, who resent having people from the Olivier Borraz 85 The sociological and economic challenges in using wastewater sludge as fertiliser for food production in France city complaining about living conditions in the countryside. These are two totally different worlds in values, manners, behaviour, etc. and sludge is just an excuse or an opportunity for these differences to come out and raise against each other groups of individuals. The same can be said of urban elected officials, the whole food production chain, wastewater treatment industrials and farmers. In all these cases, actors know very little about each other and are not able to predict one another’s behaviour. They must learn to understand each others’ stakes, interests, constraints and representations in order to come to terms with the disposal of sludge, i.e. to achieve mutual recognition, to take mutual engagements and to agree on the definition and modalities of sludge recycling. This agreement also entails coming to terms on the economic value they give to this residue and to its use in agriculture. This value as well as the terms in which the issue is settled remain strictly local, embedded in a social context of relations.

If we try to analyse the conditions that lie beneath such an agreement, it is easy to see that they refer mainly to trust and credibility : “social bonding creates solidarities of credibility.”1

It is because local stakeholders were given the opportunity to work out together a common problem and, in so doing, learn about each other, that they were able to predict each others’ attitudes, gain confidence and slowly build up trust. And once this trust was obtained, coming to terms with sludge became much easier. But these terms remained local, i.e. the participants agreed on a solution regarding their own sludge but not the one produced by neighbouring territories.

It would be mistaken to infer from this analysis that agreements can only be local – or to put it differently that the solution to sludge disposal in France can only come from a sum of local agreements. The conditions given above can also apply to national interest groups, but in a setting more limited in scope than the previous roundtable. In a sense, the main obstacle to reaching a national agreement was the diversity of stakeholders invited to the negotiation : every

1 T. Riordan, C. Marris and I. Langford, “Images of science underlying public perceptions of risk” in Science, Policy and Risk, The Royal Society, London, 1997, p. 16. 86 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna time a partial agreement seemed close at hand, a small number of participants would oppose it firmly and call for a new round of discussions, threatening to block the whole procedure. Hence, the idea is to organise discussions in more limited settings, in scale or in scope, than the national roundtable.

Limited discussions, for example those that were held recently between the water industry and the food production industry and retailers, offer better chances to reach a common representation of the issue at stake and, on this basis, achieve mutual recognition and mutual engagements. The diversity of meanings held by sludge makes it difficult for more than a limited number of participants to come to terms with it – unless the problem is very real and concrete, as is the case at the local level. Two or three stakeholders can agree on common terms, which leave aside minor aspects of the issue. Knowing that these minor aspects can be of importance for other actors who will push them forward. In other words, given the diversity of representations conveyed by sludge and given the complexity of the product, it is necessary to adapt the terms of negotiation and the institutional setting to the different dimensions of the problem, to address in different terms the different stakeholders according to their representations and interests.

Such an attitude is of importance, not only in order to find stable solutions to the problem of sludge disposal, but also in building credibility around scientific data as well as public regulation. The debates over sludge recycling in France often illustrate a well known fact : the lack of trust in scientific expertise and public officials, after a series of sanitary crisis going back to the 1980ss. The discussions organized, either at the local level or between a limited number of participants, serve precisely the purpose of building faith and credibility in scientific results and official texts, not on the basis of their innate authority but in regard to the way they are discussed, appropriated, understood and eventually completed. In other words, the agreements which can be achieved between different stakeholders are not only a social production, free of any scientific or legal basis. Quite the contrary, they rely heavily on these to organize discussions and negotiations.

In this respect, and regarding the special case of sludge, European and national regulation should not attempt to organize in detail the use of sludge in agriculture, to define precise measures and means in order to reach predefined Olivier Borraz 87 The sociological and economic challenges in using wastewater sludge as fertiliser for food production in France objectives. It should be conceived to foster discussions and negotiations capable of achieving such settlements as those mentioned above. It should neither make it harder for interest groups to reach an agreement, nor make it harder for sludge to adjust to different systems of representations. Regulation should on the contrary fix limits, define objectives and then leave it to stakeholders to find a concrete solution to reach these. Experience shows that these limited (in scale or in scope) agreements often define stricter conditions than existing regulation, but on more appropriate items.

Author: Olivier Borraz Centre de Sociologie des Organisations Centre National de la Recherche Scientifique 19 rue Amélie, F-75007 Paris e-mail: [email protected] 88 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna 89 Wiener Mitteilungen (2001) Band 171, 89-102 Copyright © 2001; Institut für Wassergüte / TU-Wien

Recovery of phosphate

P. Roeleveld and P. Piekema STOWA Dutch Foundation of Applied Water Research

Contents

• Introduction, phosphate cycle

• P-recovery incentives and potentials

• P-recovery techniques • Results of inventory study in The Netherlands

• Conclusions 90 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

Traditional P-cycle

Modern throughput P-system P. Roeleveld and P. Piekema 91 Recovery of phosphate

Future P-cycle

P-recovery incentives

Stimulating factors:

• EC Urban Waste Water Treatment Directive

• Limits to sludge application on land

• High sludge treatment costs (The Netherlands, Japan)

• P-recovery policy of industry (CEEP)

• P-recovery policy of government (Sweden, UK)

• Struvite deposit problems • A demand for sustainable phosphorus resources 92 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

Drivers for the water industry

Potential for cost savings: chemical dosing and sludge handling costs

Potential for cost recovery: sale of recovered phosphate product

Potential to enhance phosphorus removal: achieve lower effluent phosphorus concentrations

Publicity on P-recovery

Several activities to reach all actors:

• SCOPE newsletter

• two special issues of Environmental Technology

• 1st Int. Conf. in Warwick in 1998 (100 visitors) • 2nd Int. Conf. in Noordwijkerhout in 2001 (270 visitors) P. Roeleveld and P. Piekema 93 Recovery of phosphate

P-recovery techniques

Biological P-removal is a facilitating process

• Calcium phosphate formation (Crystalactor®) • Struvite precipitation (Phosnix®) • Precipitation as aluminium or iron phosphate ... But also ion exchange resins, magnetic separation, adsorption ...

And there are also different techniques for incinerated sewage sludge

P-recovery techniques

Calcium phosphate (Crystalactor®)

• Experience on full scale in The Netherlands • High quality product • Can be used by fertiliser industry and phosphate industry

Crystalactor® at Westerbork, The Netherlands 94 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

P-recovery techniques

Struvite (Phosnix®)

• Experience on full scale in Japan and Italy • High quality product • Can be used as fertiliser or in certain phosphate industry process routes

Ube Industries Sakai plant, Japan

P-recovery techniques

Ferri phosphate from sludge hydrolysis (Krepro®)

• Experience on full scale in Sweden

• High quality product

• Can be used as fertiliser P. Roeleveld and P. Piekema 95 Recovery of phosphate

Economic feasibility

Feasiblity depends strongly on circumstances per country, determining factors are:

• P-concentration in influent • sludge handling costs and disposal routes • costs of the P-recovery technique • market value of P-recovery products

Inventory study in The Netherlands

Clients: STOWA, Thermphos and CEEP

Consultant: Haskoning B.V.

Objective:

Which phosphate rich streams are available from wwtp’s that can be used for production of elementary phosphorus ? 96 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

Thermphos B.V.

Base material: Phosphate ore (600.000 tons/year)

Phosphate usage: 190.000 tons P2O5 / year

Production: Elementary phosphorus

Aim: Replacement of 20% base material by phosphate rich streams within 5 years

Option: Usage of phosphate-rich sludge from wwtp’s

Requirements for P-rich streams

• Dry solids: > 75%

• P2O5: > 18% of dry solids

• Iron (Fe): Maximum of 0,5% if P2O5=20% ? 2000 tons / year extra • Zinc (Zn): ? 20 tons / year extra • Cu / Cr / Ni / Co / V: ? 2 tons / year extra P. Roeleveld and P. Piekema 97 Recovery of phosphate

Phosphate flow through wwtp’s

Pre-settler Anaerobic Anoxic Aerobic Settler

FeCl3

( Sludge processing 24.000 tons (350.000 tons d.s. / year) P2O5 / year

63% 9% 3% 24% )* +,1% Ashes Compost Wet oxidation Thermally dried Other

Requirements versus availability

100% 90% 80% Min. D.s.% 70% 60% D.s% 50% Fe% 40% P2O5% 30%

20% Min. P2O5% 10% Max. Fe % 0% Ashes Wet dried Compost oxidation Thermally Bio-sludge 98 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

Phosphate flow through wwtp’s

Pre-settler Anaerobic Anoxic Aerobic Settler

FeCl3

( Sludge processing 24.000 tons (350.000 tons d.s. / P O / year year) 2 5

) 63% 9% 3% 24% 1% *+, Ashes Compost Wet oxidation Thermally dried Other

Bottlenecks and solutions

Metal concentration too high:

• dosing of aluminium chemicals at wwtp’s • implementation of side-stream processes - e.g. with the Crystalactor®

P2O5 concentration too low: • implementation of side-stream processes - e.g. with the Crystalactor® P. Roeleveld and P. Piekema 99 Recovery of phosphate

Side-stream implementation

Pre-settler Anaerobic Anoxic Aerobic Settler

Precipitation Sludge separation Thermphos

Crystalactor®

Qualification of side-stream sludge

Precipitation D.s.% = 2%

P2O5%=29%Further research Cu/Zn/Fe = <<<

Crystalactor® D.s.% = 90%

P2O5%=24%Feasible ! Cu/Zn/Fe = <<< 100 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

Perspective for The Netherlands

Current : 72 wwtp’s with Bio-P removal Within 2010 : 29 to be built with Bio- removal

Max. 5% of Thermphos base material

Conclusions of the inventory

• Yearly amount of P2O5 from wwtp’s : 24.000 tons • Main bottlenecks for usage by Thermphos B.V.: - Too low dry solids concentration

- Too low P2O5 concentration - Too high metal concentration (Fe / Cu / Zn)

• Direct usage of wwtp-sludge : Not feasible

Solution : implementation of Crystalactor® Covers all bottlenecks About 5% of Thermphos base material can be made available within 2010 P. Roeleveld and P. Piekema 101 Recovery of phosphate

Results from the 2nd Int. Conf.

For the situation in the Netherlands

• Besides Thermphos, also the fertiliser industry became interested • Therefore the Crystalactor® is not the only option, also struvite and iron precipitation can be applied • A working group will be formed with all actors in the industrial column of P-recovery, also animal waste, waste processing and different industries • The P-recovery working group will start a lobby towards the regulators

P-recovery web site

For more information:

visit the P-recovery website on

http://www.nhm.ac.uk/mineralogy/phos 102 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

Examples of other Dutch research

• Reduction of sludge by higher organisms (predators)

• Energy recovery from sludge (e.g. pyrolysis)

• Sludge reduction by ozone

• Reduction of pollution by dispersed sources (is a slow proces)

The sludge cycle is one of the important issues in the research strategy of STOWA 2001 - 2005

References

1st International Conference on Phosphorus Recovery from Sewage and Animal Wastes, Warwick University, UK, 6th & 7th May 1998.

2nd International Conference on Recovery of Phosphates from Sewage and Animal Wastes, Noordwijkerhout, Holland, 12-13 March 2001 Authors: Peter Piekema DHV Water BV P.O. Box 484 NL-3800 AL Amersfoort Paul Roeleveld STOWA P.O. Box 8090 NL-3503 RB Utrecht Tel: +31 30 232 1199 Email: [email protected] 103 Wiener Mitteilungen (2001) Band 171, 103-112 Copyright © 2001; Institut für Wassergüte / TU-Wien

Sludge Disposal of the city of Zurich (co-incineration, actual and future options)

Ch. Leitzinger Entsorgung und Recycling Zürich

structure

short presentation of the Waste Management of the city of Zurich history and actual situation of the sludge-disposal demands of the sludge-disposal agricultural utilization thermal utilization future options 104 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

Scope of duties of the Waste Management to transform thermical energy Department are from solid waste to clean the city - streets to deliver of heat to - parks to transport solid waste the district heating

to build and to to run and to maintain the maintain the waste- sewage-system water- treatment plant Ch. Leitzinger 105 Sludge Disposal of the city of Zurich (co-incineration, actual and future options)

ORGANISATION ERZ (valid from 01.04.01) board of directors

sewage compost- and city cleaning transport- waste district system wastewater logistics incineration heating treatment plant plant operative divisions

commercial services

finance services

marketing and sales

Public Relations

service divisions human resources

special projects

important material fluxes wastewater- treatment plant

120‘000 t solid 160‘000 t solid waste waste Zürich 11‘000 t sludge dm (90% dm)

WIP 2 WIP 1 heat production heat production deficit surplus 106 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

wastewater treatment plant Werdhölzli

population equivalent: 425‘000 average flow: 70 mio m3 / year cleaning performance: carbon (TOC) 6950 t / year, (95 %) nitrogen (tot. N) 1180 t / year, (66 %) phosphorus (tot. P) 290 t / year, (90%) screenings 1825 t / year grit chamber material 1500 t / year grease / oil 180 t / year sludge quantity: 11‘000 t dm / year

wastewater- treatment plant Werdhölzli

water treatment preliminary treatment (screen, primary treatment) denitrifikation nitrifikation phosphate precipitation filtration Ch. Leitzinger 107 Sludge Disposal of the city of Zurich (co-incineration, actual and future options)

wastewater treatment plant Werdhölzli

sludge treatment

anaerobic digestion sludge dewatering (30% dm) sludge drying (90% dm)

composition of the sewage sludge

activated sludge organics 70% anorganics 30%

SiO2 Fe2O3 CaO Al2O3 degradably (55 %) not degradably (45 %) (30-50 %) (20 %) (15 %) (10 %)

sludge stabilisation

bio - gas stabilized sludge

organic substance anorganic substance 108 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

requests of the sewage sludge disposal

continuity

law disposal security

ecology economy

continuity

prolonged period

few alternatives continuity of the disposal

long development times

(t TS / a)

15000

10000

5000

0 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000

agriculture cement industry Ch. Leitzinger 109 Sludge Disposal of the city of Zurich (co-incineration, actual and future options)

disposal reliability

continuous increasing influence on waste sludge- concentration water treatment limited batch/stock few customers capacity clear disposal volume reduction solutions

1200 professionalism 1200 1070

1000

800 590 600 2.5 % 4.0 % 400 5.0 % 100 30

200 30 % 90 % sludge output(t day) / 0 r n io y st Drying ge i watering D e Primar D re-Thickene SedimentationP

economy

cost structure 9 900

8 800

7 700 sludge treatment 6 600 13.4 5 500 44 % 4 400 (Mio CHF) (CHF / t dm) water treatment 3 300

2.4 2 200 8 % 14.9 1 100 48 % 0 0

sludge disposal 6 7 8 90 91 92 93 9 9 9 9 9 9 9 1 1 1 1 1994 1995 19 19 19

total netto costs: 30.7 Mio transport and utilization costs specific costs 110 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

ecology

0.2% heavy metals 5% Al2O3

9%CaO

10% effective use of the Fe2O3 valuable material the whereabouts of the pollutants

comparison of the 25% SiO2 51% different ways energy

development of the sludge disposal

12000

10000

8000 burn

6000 landfill agriculture 4000 cement industry (t dry material / year) 2000

0 1995 1988 1989 1990 1991 1992 1993 1994 1996 1997 1998 1999 2000 2001 burn tests in the waste incineration plant Ch. Leitzinger 111 Sludge Disposal of the city of Zurich (co-incineration, actual and future options)

requests for the sewage sludge disposal

? continuity ? ? ?? law disposal ? agricultural use of disposal sewage sludge ? reliability

?? ecology economy ??

important material fluxes wastewater- treatment plant

less solid more solid waste waste Zürich 4‘000 t dm 7‘000 t dm (30% dm) (90% dm)

WIP 2 WIP 1 heat production heat production smaller deficit smaller surplus 112 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

the benefit of incinerating sludge in the waste incineration plant

ecological benefit balanced energy - management economic benfit smaller cash flow possibility to sell sludge disposal capacity long term basis for price control disposal reliability 2 very strong customers

Author: Dipl.Ing. Christoph Leitzinger Entsorgung und Recycling Zürich Bändlistraße 108 CH-8010 Zürich Telefon +41-1/645 55 30 e-mail: [email protected] 113 Wiener Mitteilungen (2001) Band 171, 113-130 Copyright © 2001; Institut für Wassergüte / TU-Wien

Raw sludge incineration in Vienna (3 Mio PE) and its implications on waste water treatment (20 years of full scale experience)

F. Klager*, H. Kroiss **, F. Tikovsky*** *Entsorgungsbetriebe Simmering GmbH, Wien, **Vienna University of Technology, *** Fernwärme Wien AG

1 Introduction

Vienna has a population of about 1,8 Mio inhabitants and an area of about 400 km2. Most of the settled area is equipped with a combined sewer system with relatively long interceptors along the rivers. The dominating river is the Danube (mean flow ~ 1800 m3/s), which is also the final receiving water for the waste water.

In the near future all the waste water collected during dry weather will reach the Main Waste Water Treatment Plant of Vienna (MTPV) which belongs to the largest municipal treatment plants (4 Mio PE) in the world. The existing treatment plant is in operation since 1980. Therefore 20 years of development and experience with sludge treatment and disposal can be reported. At the same time it is possible to show the close relationship between waste water and sludge treatment in regard to process reliability and treatment efficiency.

2 Historic development

The permit for the existing Main Treatment Plant of Vienna dates back to the years 1969 and 1970. This plant was designed for 3 Mio. population equivalents (PE). The treatment efficiency requirement was a 70% BOD-reduction. The limnolgists at that time only claimed mechanical treatment. The process technology is a conventional mechanical biological treatment with a high rate 114 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna activated sludge process (MCRT ~ 1 day). The basic design for the sludge treatment and disposal consisted in thickening anaerobic mesophilic digestion and agricultural use of the digested sludge without mechanical dewatering using large storage ponds in the agricultural area.

Intensive field investigations into the land application of the sludge at the large agricultural area in the northeast of the City showed this solution to be feasible from the economic, technical and environmental considerations. These investigations included a campaign for confidence building with the farmers of the region.

Finally this solution failed on the political level as no agreement could be achieved in regard to the reliability requirements for sludge disposal claimed by the City of Vienna. Already at this time the main problem with agricultural use of sewage sludge of today was detected. As a consequence of the failure to reach a reliable solution the construction of sludge treatment facilities was stopped and new concepts of sludge treatment and disposal had to be discussed, while the construction of the waste water treatment facilities was nearly finished. It took several years to agree on a new solution that was based on the following concept:

S Thickening of the raw sludge on site of the MTPV

S Pumping the thickened sludge to a newly established private company (EbS) for sludge handling and disposal and for hazardous waste treatment and incineration. The sludge line consisted of dewatering by centrifuges and fluidised bed incineration and “adequate” off-gas treatment facilities.

S Using the excess heat from incineration for electric power production and district heating

S Landfill disposal of slag and ashes at a municipal land fill site.

The long decision period including the discussion on air pollution requirements resulted in a marked delay of the project. In June 1980 both plants went into operation.

The first years of operation revealed many problems caused by a lack of experience in design and operation of raw sludge incineration plants but also F. Klager*, H. Kroiss **, F. Tikovsky*** 115 Raw sludge incineration in Vienna (3 Mio PE) and its implications on waste water treatment (20 years of full scale experience) the difficulty to co-ordinate a public and a private operated enterprise for optimum overall performance. Many of these problems also affected the waste water treatment efficiency. During the first years of operation a continuous improvement of the situation occurred, the sludge handling and off-gas treatment technology was further developed and optimised and only one responsible operator for both plants was installed. Meanwhile an economic, reliable and environmentally sound solution for sludge and hazardous waste treatment and disposal can be demonstrated.

Due to the development in population, waste production, legal requirements and technology the future extension of both plants is on the way.

3 Waste Water Treatment Plant

3.1 Present situation

The Main Treatment Plant of Vienna actually treats approx. 90% of the Vienna sewage. Only the Blumental plant serves the drainage area of Liesing with separate sewer system in the south of Vienna. In addition some of the surrounding communities are also connected to MTPV.

The MTPV processes an average daily flow of ~500,000 m³, the actual BOD load is corresponding to ~3.25 million PE. The existing plant is designed for the biological treatment of a maximum flow of 12 m³/sec while the mechanical treatment for a maximum rain weather flow of 24 m³/sec. The mean dry weather flow is about 6m3/s, the peak flow about 9 m3/s.

Six screw pumps raise the wastewater to the six fine screen (6mm) lines followed by rectangular grit chambers. The screenings are dewatered and transported to sealed containers for incineration. This is also the case for the material collected in the gravel traps and grit chambers. The degritted waste water is divided into two symmetric treatment lines consisting of primary and biological treatment. Mechanical treatment consists of eight rectangular settling tanks with a total surface of 9.470 m² and a volume of 28.500 m³. The primary effluent discharges to four aeration tanks with a total volume of 42.000 m³. The activated sludge is aerated by 32 cone aerators. The activated sludge is evenly 116 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna distributed to 16 rectangular secondary settling tanks with scrapers, where the sludge is separated from the treated effluent. Two screw pumps return the settled sludge to the aeration tanks. The effluent is discharged into the Danube Canal as receiving water.

Primary and secondary sludge from the mechanical and biological treatment process are pumped to four thickeners. The thickeners have an overall capacity of 13.500 m³. They are completely covered and equipped with biofilters for odour control. Gravity thickening results in total dry solids (TDS) concentrations of up to 5,0 %.

3.2 Expansion of the Main Treatment Plant of Vienna (under construction)

3.2.1 Treatment efficiency and capacity requirements (design data) In 1996 a new emission regulation was issued by the Austrian Federal Ministry for Agriculture and Forestry in accordance with the EU Guideline for Municipal Waste Water 91/271.

According to the Austrian regulations waste water treatment plants >50.000 PE have to meet the following minimum requirements relevant for the MTPV: F. Klager*, H. Kroiss **, F. Tikovsky*** 117 Raw sludge incineration in Vienna (3 Mio PE) and its implications on waste water treatment (20 years of full scale experience)

Table 1: Effluent standards for municipal waste water treatment (1996)

Parameter Dim. compliance

BOD5 mg/l 15 95 percentile

COD mg/l 75 95 percentile

NH4-N* mg/l 5 95 percentile

TotN-removal % 70 yearly mean**

TotP mg/l 1,0 yearly mean

*Temperature >8°C, ** Temperature > 12°C in the aeration tank. The concentrations must never exceed 200% of the standards. The compliance is based on daily flow proportional composite homogenised samples, and daily sampling (Self end external monitoring).

These standards are in accordance with EU 91/271 guideline for “sensitive areas” and include a requirement for nearly complete nitrification throughout the year.

In order to meet the above mentioned requirements and to cope with the anticipated future development of waste water flow and pollution load it is necessary to:

S change the treatment concept and

S enlarge the capacity

Due to the growth of Vienna’s population and additional sewer connections within and outside of Vienna, the wastewater pollution load is expected reach 4.0 million population equivalents by the year 2010.

The design of the extension is based on the following data:

mean dry weather flow 680.000 m³/d, peak 9,4m³/s

maximum wet weather flow 18 m3/s

BOD-load 240 t/d. 118 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

In order to reduce combined sewer overflow to the receiving rivers the large volume of the interceptors will be used for storage during rain weather conditions applying flow control systems.

3.2.2 Biological treatment process The selection of the process was guided by the following principles:

1. Reliability to meet the legal requirements

2. Flexibility in operation

3. Minimisation of costs

4. No discharge of untreated waste water during extension phase

Many different variants were suggested several even tested in pilot scale. A comprehensive evaluation finally led to the selection of a novel two stage activated sludge process concept which makes optimal use of the reactor volume at any time of the year i.e. for all temperature ranges. It combines the advantages of two stage process for reliable nitrification with optimal use of the volume for denitrification in both stages (recirculation of treated effluent from the second stage to the first stage for denitrification, bypass of primary effluent to the second stage, and use of the sludge of the first stage as substrate for denitrification in the second stage (Hybrid process), recirculation of the excess sludge of the second stage to the first stage in order to enable nitrification also in the first stage) This concept does only little affect the existing plant and enables different operational modes. F. Klager*, H. Kroiss **, F. Tikovsky*** 119 Raw sludge incineration in Vienna (3 Mio PE) and its implications on waste water treatment (20 years of full scale experience)

BP BYPASS SC 2 SC 1 HYBRID®

RS RS

ES RF

BP Bypass line SC 1 Sludge circulation line 1 RS Return sludge RF Recirculation flow SC 2 Sludge circulation line 2 ES Excess sludge

Figure 1: Treatment scheme for the extension of the MTPV

3.2.3 Pilot investigations and dynamic simulation In order to verify the selected process configuration under real conditions and to develop a mathematical model for the process a comprehensive pilot investigation program was started on site of the MTPV in close co-operation with the Institute for Water Quality and Waste Management of the Vienna University of Technology.

The results clearly show that it will be possible to achieve the required treatment efficiency under different loading conditions, temperatures and also during typical repair and maintenance situations. In order to simulate the different operational modes of the plant and to design and optimise the control and monitoring system for the plant the commonly applied activated sludge model (ASM) had to be adapted to the special conditions of this two stage process. With the new dynamic model “ASM-Vienna”, developed at the University of Technology it is possible to verify the N-removal efficiency which has to be met as a yearly mean using the operational data from the existing Treatment Plant. It is possible to simulate the N-removal capacity for different (automatic) control strategies. With the help of this dynamic simulation tool it will also be possible to check the consequences of operational changes before they are transferred to practical application. 120 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

3.2.4 Realization of the second stage The newly built second stage activated sludge plant consists of 15 lines with one aeration tank and one secondary sedimentation tank each. The total aeration tank volume is 171.000 m3 . There is an intermediate pumping station after which the mixture of wastewater ( e.g. effluent of the first stage) and return sludge from all lines is distributed into the 15 lines.

The aeration tanks are subdivided into three main cascades. The first cascade is not aerated and acts as pre-denitrification tank. The following two cascades of the aeration tank can be operated as simultaneous nitrification/denitrification tanks. The aeration capacity and the aerated volume can be controlled in a wide range in order to meet the two main goals at the same time. The first goal is to have stable nitrification which is strongly influenced by the temperature. The second goal is to achieve maximum N-removal by denitrification in the anoxic zones of the aeration tanks.

In regard to N-removal there is a strong influence of sludge treatment technology on the denitrification requirements in the biological treatment system. Due to the low sludge age in the first stage (existing plant) up to 45% of the nitrogen content in the influent is contained in the raw sludge. Due to the short detention time in the thickening and dewatering stage of the sludge treatment system most of the nitrogen remains with the solids. As they are immediately incinerated after dewatering. About 40% of the nitrogen is removed from the water without using denitrification. In order to achieve a 70% nitrogen removal only 30% of the nitrogen content of the raw waste has to be removed by denitrification.

In the case anaerobic sludge digestion is applied before disposal only about 15 to 20 % of the nitrogen in the influent remains in sludge leaving the treatment plant. The rest (up to 20 % of the nitrogen contained in the influent) will be returned to the influent by the supernatant and filtrate from post-thickening and dewatering processes. As a consequence the denitrification capacity has to be in the range of at least 50% of the nitrogen load in the influent. This normally is not a problem for one stage activated sludge processes but is an important challenge for two stage processes. There are several separate treatment processes for nitrogen removal from the return flows of sludge handling but they cause additional costs. F. Klager*, H. Kroiss **, F. Tikovsky*** 121 Raw sludge incineration in Vienna (3 Mio PE) and its implications on waste water treatment (20 years of full scale experience)

As a consequence of the implications of sludge treatment and nitrogen removal by denitrification it has to be considered that cost comparisons of different waste water treatment processes must include the sludge line and the nitrogen return flows from there. Phosphorus removal normally is not affected by the sludge treatment.

Enhanced biological phosphorus removal in the first biological stage will play a limited role. The reliability of phosphorus removal will be provided by simultaneous phosphate precipitation with iron salts in the aeration tanks.

The 15 circular secondary clarifiers have a diameter of 64 meters. The clarifiers are equipped with double scrapers and submerged outlet pipes. Part of the nitrate-containing effluent from the secondary clarifiers is recirculated to the first stage during dry weather flow for denitrification in the first cascade of the high loaded aeration tank. At maximum wet weather flow conditions this recirculation will completely be stopped. By the recirculation control a nearly constant hydraulic loading of the secondary clarifiers is achieved.

Due to the extension of the waste water treatment plant also sludge production will increase. The following table shows the design data which have been developed for the adaptation of the sludge handling facilities from today until the year 2015. All data are for dry solids production in t/d.

Table 2: Dry solids production, design data. In t/d.

Year Dim. Median 85%-percentile Max. RW

1997 t/d 180 220 280

2005 (before extension) t/d 210 240 300

2005 (after extension) t/d 230 250 320

2015 t/d 245 265 345 122 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

4 Sewage Sludge Treatment

4.1 General remarks

Actually ~ 1,5 million tons of thickened sludge per year with approx. 5 % dry solids (DS) are produced in the MTPV. This corresponds to a mean sludge load of about 210 (metric) tons of dry solids per day. The daily sludge production has to be dewatered by centrifuges and incinerated.

In practice the sludge production in the waste water treatment plant strongly varies from day to day and even from month to month as can be seen from the following figure. This is one of the challenges for design and especially for the operation of raw sludge incineration plants.

The main causes for these variations are sediment accumulation in the sewer system during dry weather and rapid transport to the treatment plant during high flow situations especially at the beginning of rain or snow melting events. Such events can cause DS production up to ~ 240 t/d. Immediately after such rain events primary sludge production is strongly reduced due to sediment build-up in the sewer system. If this coincides with weekends during summertime sludge production can go down below 100 tDS/d due to the low pollution load reaching the MTPV. As primary sludge has better dewaterability characteristics as secondary sludge the peak loads of DS are normally linked with high DS concentrations in the dewatered sludge and a lower calorific value. This reduces the variation of the required incineration capacity. In the future it is planned to equalise the incineration requirements by having a mixed incineration of other wastes. F. Klager*, H. Kroiss **, F. Tikovsky*** 123 Raw sludge incineration in Vienna (3 Mio PE) and its implications on waste water treatment (20 years of full scale experience)

DS (t/d) 300

250

200 February 2000

150

sludge production 100

August 2000 50

0 1 2 3 4 5 6 7 8 9 10111213141516171819202122232425262728293031 days

Figure 2: Sludge production. Dry solids in t/d.

Raw sludge normally is already anaerobic when it reaches the thickeners at the MTPV, this is especially the case in summertime at high temperatures. The detention time of the solids in the thickeners has to be optimised in regard to the dewaterability characteristics. They rapidly deteriorate if gas production from anaerobic degradation processes starts due to a too long detention time. Small gas bubbles attached to the sludge flocs and enclosed into the large flocs created by the addition of flocculants cause a marked decrease of the density of the solids. This in turn reduces the separation and dewatering characteristics in centrifuges.

The pre-thickened sludge from the thickeners at the MTPV is pumped into one of two storage tanks. The storage tanks compensate for unsteady sludge delivery. In order to maintain good dewatering characteristics an overall detention time of the sludge in the thickeners and storage tanks should never exceed one day. From these storage tanks the pre-thickened sludge is pumped to the sludge dewatering stations via two ring-pipes.

In order to improve the sludge dewatering characteristics the sludge is preheated and flocculants are added before entering the centrifuges. The dewatered sludge produced by two adjacent centrifuges is collected in the 124 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna hopper of one piston pump. These piston pumps transport the dewatered sludge through a high pressure piping system to the fluidised bed incinerators. The dewatered sludge is incinerated at a temperature of about 850 ° C. The energy content of the gas is used for electric power generation.

The ash produced during the incineration is contained in the flue gas and is removed by means of electrostatic precipitators. This water insoluble ash is transported to a landfill. The flue gas is cleaned in a wet scrubbing system and activated carbon filters.

Due to the extension of the MTPV for better treatment efficiency and higher pollution loads an increase in the sewage sludge production of about 20 % has to be assumed. The sludge treatment capacities at the incineration plant have to be extended at the same time as the waste water treatment plant.

4.2 Dewatering in centrifuges (decanters)

Sludge dewatering plays a decisive role in several aspects. The separation efficiency is responsible for the return of solids with the centrate to the waste water treatment plant, where these solids can cause intensification of anaerobic processes in the primary sludge and in the worst case a decreased MCRT in the aeration tanks. The DS concentration in the dewatered sludge (cake) is very important for the energy balance. As the two requirements (excellent solids separation and high DS concentration in the cake) normally cannot be achieved with the same operational scheme a difficult optimisation process for the operation of the waste water and the sludge handling processes is essential. A lot of effort was put in the optimisation of the dewatering process in order to minimise the addition of external fossil energy sources.

The sludge dewatering station consists of 22 large high speed centrifuges. The choice to use centrifuges for sludge dewatering was based on their favourable operational characteristics, as continuous operation, low space requirements, high efficiency and closed machinery, which is especially important in regard to odour control with raw sludge

From the very beginning it was the aim to realise a self-supporting incineration of the sewage sludge which can only be achieved by reducing the water content of the dewatered sludge cake. In this way it is possible to fully use the F. Klager*, H. Kroiss **, F. Tikovsky*** 125 Raw sludge incineration in Vienna (3 Mio PE) and its implications on waste water treatment (20 years of full scale experience) incineration capacities for the sludge disposal instead of burning oil. The limit for mechanical dewatering of municipal sludge lies in the range of 40-45 % DS. By increasing the temperature before the centrifuges to about 50°C in heat exchangers the DS concentration could be raised from about 35 % to 39 %. At the same time the flocculent consumption could be reduced by about 10 %.

4.3 Incineration in Fluidised Bed Furnaces

Fluidised bed technology (FBC) is a very proven system for the incineration of sewage sludge. Some of the well known advantages of fluidised bed incinerator technology are:

S excellent reactive conditions in the fluidised bed

S relatively low temperatures with perfectly even temperature distribution

S very good burn out and incineration efficiency

S no moving components in the combustion chamber

S decreased excess air volume with reduced exhaust gas volumes

At the sludge treatment plant the dewatered sludge is transported by twin-piston pumps through a high-pressure piping system to the fluidised bed incinerators. The longest distance between the pumps and the incineration is almost 220 meters. For the improvement of the transport characteristics of the dewatered sludge a polyelectrolytic lubricant is added by high pressure pumps.

The furnace has to be started up with burners until the corresponding temperatures are reached. The minimum bed temperature is approx. 600 ° C, the freeboard temperature approx. 700 – 800°C. Sludge is pumped directly into the sand bed causing a nearly 10 % higher capacity-rate in comparison to an input above the bed.

Three stationary fluidised bed units are in operation, two designed for a capacity of 120 t DS/d, one for 160 t DS/d according to a content of 36 % DS in the dewatered sludge. 126 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

Due to the expected increase in the sludge volume the installation of a further fluidised bed reactor is necessary. A special feature of this fourth fluidised bed incinerator will be the co-incineration of pre-treated municipal waste and dewatered sewage sludge. The design capacity of this specially adapted furnace will be:

S for dewatered sewage sludge 160 t DS/d (36% DS; 68% organic DS; 14 MJ/kg heating value)

S for municipal waste 288 t/d (20% ash; 20 % water content; 11 MJ/kg heating value).

The pre-treated municipal waste will be supplied comminuted with a maximum length of 250 mm and free of iron and non iron metals. A combined incineration of sewage sludge and waste is possible which enables an optimisation of the incineration plant operation

The following materials can also be added to this incinerator in a smaller amount:

S dried sewage sludge

S used activated carbon

S waste oil

S waste solvents

S pre-treated plastics

Such a flexible composition of the feed material gives more flexibility for the economic optimisation of waste management for the city of Vienna.

4.4 Flue Gas Cleaning System

All incineration lines for the sewage sludge and hazardous waste have the same flow sheet for flue gas cleaning:

- electrostatic precipitator (with three fields) for dust separation F. Klager*, H. Kroiss **, F. Tikovsky*** 127 Raw sludge incineration in Vienna (3 Mio PE) and its implications on waste water treatment (20 years of full scale experience)

- denoxing System - SNCR (selective non catalytic reduction of NOx)

- heat shift system

- wet scrubbing system for halogen and SO2 removal

- activated coke adsorption filter to cut the dioxin/furan/mercury emissions to the required level

- analytic control system

- liquid residue treatment

The principle of the Denox process is the reduction of NOx with a 25% aqueous ammonia solution which is added behind the furnace at temperatures between 850 °C and 1050°C

The flue gas is cleaned in two scrubbers. HCl, HF, heavy metals and mercury are separated in the first scrubber whereas SO2 is separated in the second scrubber. The waste waters derived from the wet cleaning system of all incineration lines are purified in two identical waste water treatment lines.

The last step in the flue gas cleaning system is the activated carbon adsorption filter. Remaining pollutants after the scrubbing (organic substances, dioxins, furans and mercury) are separated there. A counter-current type of reactor is used. The charged carbon is directly fed to the fluidised bed incinerators. 128 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

Table 3: Off gas standards and the historic and actual operational data

Compound Dim. Operational Operational Standards results after results today emission start up (1988) regulation

Hg mg/Nm3 0,12 < 0,0008 0,05 PCCD/F ng/Nm3 0,4 (CHC) 0,018 0,1 dust mg / Nm3 0,7 < 0,3 10,0 3 SO2 mg / Nm 3,8 1,6 50,0 HCl mg / Nm3 0,4 <0,1 10,0 HF mg / Nm3 0,02 < 0,1 0,7 Pb Zn mg / Nm3 0,016 Sum 0,0016 Sum 0,5 Cr As mg / Nm3 < 0,001 < 0,0075 Ni mg / Nm3 < 0,006 0,00009 Cd mg / N m3 < 0,001 0,0134 Cu mg / Nm3 < 0,001 0,00009 Sum 0,5

The whole flue gas cleaning system has a present capacity of 464.000 Nm3/h. After the installation of the fourth fluidised bed line it will be increased up to 538.000 Nm3/h.

The ashes from the incineration process and the filter cake from the water treatment system are put to landfills.

The multistage cleaning process ensures that the standards of the Austrian Clean Air Act are met.

4.5 Power Management

In each incineration line a 3-draught steam boiler is installed. The steam generated in the boiler drum leaves the boiler with a pressure of 53 bar and with a temperature of 350 ° C. F. Klager*, H. Kroiss **, F. Tikovsky*** 129 Raw sludge incineration in Vienna (3 Mio PE) and its implications on waste water treatment (20 years of full scale experience)

Two steam turbines with generators are installed. The capacity of the steam turbines is approx. 90 t steam/h.

On the one hand steam is used for the production of electricity, which is completely used on site. The electric capacity installed is 8,0 MW.

On the other hand steam is used for preheating the combustion air and boiler feed water as well as also for district heating after heat transformation. The thermal capacity installed is 40,0 MW.

5 Conclusion

From more than 20 years of full scale operation of the Main Treatment Plant of Vienna and the sludge treatment and disposal via dewatering and incineration the following conclusions can be drawn:

S As the successful operation of the waste water treatment plant fully relies on reliable sludge disposal at any time and as they are linked by material and energy flows design and operation of both plants can only be optimised together. This is especially true for raw sludge incineration as this sludge cannot be stored for more than about one day without severe operational problems on both sides.

S Raw sludge incineration offers the opportunity to remove up to 40% of the nitrogen in the influent of the treatment plant with the sludge. This in turn results in cost reductions for N-removal at the treatment plant.

S Raw sludge incineration with highly efficient dewatering before incineration and an sophisticated air cleaning technology results in an economic, reliable and environmentally sound solution for sludge disposal even in a long prospective.

S Raw sludge incineration is only favourable for large treatment plants and small distances between waste water treatment and sludge incineration. The operation of the complex incineration plant together with hazardous waste treatment needs excellent well trained personal 130 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

and special expertise in repair and maintenance and trouble shooting as sludge production cannot be stopped.

S Due to the low emissions to the air the influence of the incineration plant on air quality in Vienna is hardly detectable.

S The co-incineration of sewage sludge and pre-treated solid waste fractions will improve the operation of the fluidised bed incineration plant and make it more economic.

By the end of the year 2004 an Austrian regulation prohibits landfill disposal of materials with an organic content of more than 5 % total organic carbon (TOC). The sludge treatment an disposal system of the City of Vienna will not be affected by this new legal situation. Regarding the actual development in agriculture and soil protection policy a reliable disposal option in agricultural use, landscape engineering or land reclamation cannot be achieved even an excellent stabilisation (e.g. by anaerobic sludge digestion) would be installed.

The decision to use raw sludge incineration for the MTPV 25 years ago was a very courageous and risky decision by the city council of Vienna at that time. From the actual and future prospective it was a wise decision.

Authors: Dipl.Ing. Franz Klager EBS GmbH 11. Haidequerstraße 6 A-1110 Vienna e-mail: [email protected] o.Univ.Prof. Dipl.Ing. Dr. Helmut Kroiß Institute for Water Quality & Waste Management Vienna University of Technology Karlsplatz 13/226 A-1040 Vienna e-mail: [email protected] SR Dipl.Ing. Franz Tikovski Fernwärme Wien GmbH Spittelauer Lände 45 A-1090 Vienna e-mail: [email protected] 131 Wiener Mitteilungen (2001) Band 171, 131-142 Copyright © 2001; Institut für Wassergüte / TU-Wien

Sludge treatment and disposal strategies in Sweden

Peter Balmér VA-strategi , Sweden Abstract: The developments in sludge treatment and disposal, sludge quality and regulations in Sweden are briefly reviewed. Present sludge quality is presented. The current discussion on sludge quality and sustainability is reviewed and future options for sludge treatment and disposal are discussed.

1 Developments in wastewater treatment and sludge disposal

In the mid 1960-ies about one third of the sewered population in Sweden was connected to secondary treatment plant, one third to primary treatment plant and one third had no treatment. Some sludge was disposed of in agriculture and some in landfills. Most municipalities experienced no major problems with sludge disposal.

By the end of the 1960-ies the number of wastewater treatment plants (WWTP) began to increase rapidly due to government subsidies of investments in WWTP. The new plant had all secondary-chemical treatment or chemical treatment. Existing plants were also upgraded to chemical treatment. As a result sludge volumes increased.

With the introduction of atomic absorption spectrophotometry in the end of the 60-ies heavy metals were detected everywhere and also in sludge. This caused considerable concern. The national health authority made a survey of the sludge quality at the Swedish WWTP and found that the quality at plants with no or small industrial connections fell within the range given in table 1. This quality was judged as acceptable for application on farmland and was taken into the regulations. The presence of regulations seemed to restore the confidence in sludge quality. In the 70-ies and up to 1986 a large part of the sludge was disposed of on agricultural land but a large part was also landfilled. 132 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

Table 1: Concentrations of heavy metals in “non-polluted” sludge around 1970

Metal “Normal concentration” mg/kg DS

Cadmium 5-15 Chromium 50-200 Copper 500-1500 Lead 100-300 Mercury 4-8 Nickel 25-100 Zinc 1000-3000

During these years the policy of the National Swedish Environmental Protection Agency was that industrial discharges and landfill leachates after adequate pretreatment should be connected to municipal WWTP. The industrial connections and the presence of sludge quality regulations made industrial discharge surveillance an important tasks for all major wastewater treatment agencies. The quality of WWTP sludge improved considerably as can be seen if data in table 1 are compared to table 2.

2 Present sludge quality and regulations

Levlin et al. (2001) as compiled sludge quality data of 1997 for 171 of the 289 municipalities in Sweden. The data is reproduced in table 2. The 10-percentile values can be assumed to be representative of the sludge quality at treatment pants with no industrial connections and with separate storm sewers in the catchment area. Balmér (2001) compiled data on different sources of heavy metals to a large WWTP and made a prediction of attainable sludge quality if only households were connected to the plant. Balmér´s attainable values agree well with the 10-percentile values of Levlin et.al. Peter Balmér 133 Sludge treatment and disposal strategies in Sweden

Table 2: Concentrations of heavy metals in Swedish wastewater sludges in 1997 and regulated maximum allowable concentrations.(Levlin et.al. 2001)

Metal 10-percentile median 90-percentile max. conc.

mg/kg DS mg/kg DS mg/kg DS mg/kgDS

Cadmium 0.59 1.10 1.88 2 Chromium 13 23 48 100 Copper 120 270 580 600 Lead 13 27 54 100 Mercury 0.35 0.80 1.60 2.5 Nickel 6.6 12 25 50 Zinc 264 450 720 800

Table 3: Maximum allowable annual loading of heavy metals on agricultural soil calculated as a 7-year average.

Metal loading g/ha,year

Cadmium 0.75 Chromium 40 Copper 300 Lead 25 Mercury 1,5 Nickel 25 Zinc 600

In table 2 are also given the maximum acceptable concentrations of heavy metals if sludge is used on agricultural land. In table 3 the maximum annual loading of heavy metals on agricultural land is given. The addition of sludge may also depend on the phosphorus concentration. The acceptable addition of phosphorus, calculated as a 7 year average, depends on the phosphorus status of the soil. For most Swedish soils the acceptable load is 22 kg P/ha,year. This 134 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna means that for many sludges it is a heavy metal that is the limiting factor. The limiting metal is in most cases cadmium but also copper and lead are often limiting.

The content of anthropogenic organic substances is not regulated but in a guiding document recommendations for maximum concentrations are given. In table 4 these values are given together with actual data from Levlin et.al.(2001). Nonyl-phenol-etoxylate tensides are phased out from detergents and many other products and there is a continuing decrease in concentrations.

Table 4: Median concentrations of some organic substances in wastewater sludge 1997

Substance concentration

mg/kg DS

Nonylphenol 16 Toluen 1.0 PAH, sum of six 1.2 PCB, sum of seven 0.59

3 Sludge treatment and disposal

Practically all medium-sized and large WWTP digest and dewater the sludge. Some plants have aerobic stabilisation and some treat the dewatered sludge with quick-lime.

The annual amount of sludge according to the national survey is 221,000 tons DS. Based on per capita sludge production data from well-controlled plants, the author believes the actual figure to be somewhat lower.

The national farmers association has recommended it´s members not to use sludge. In spite of this it is believed that about 20 % of the sludge is applied to agricultural land. During the last years increasing amounts of sludge has been Peter Balmér 135 Sludge treatment and disposal strategies in Sweden used for the production of soil substitutes that are used at roadsides, on golf courses and for similar purposes. A considerable amount of digested and dewatered sludge is also used directly without further processing in urban areas. Since January 2000 there is a landfill tax of 250 SEK/ton. This gives incitements to find other outlets for sludge than landfilling.

4 Current topics in sludge discussions

4.1 Hygiene

Present regulations have no requirement for hygienisation of sludge but there are strong restrictions on where and then sludge can be applied. This means that in practise sludge can be used only on land for the production of corn and oilseed crops. These restrictions have so far given sufficient protection. Recent out-breaks of animal diseases in Europe, increasing tourism, fear of resistant bacterial strains etc has put focus on the hygienic quality of sludge. The present regulation are now under review and the author believes that the outcome will be new regulations with stricter hygienic requirements. For the larger and medium-sized treatment plants this is not believed to cause any major problems. The smaller plants can encounter considerable problems if the regulations do not take the special situation for these plants into account.

4.2 Cadmium levels

The relation between cadmium intake any kidney damage is widely accepted in the medical profession. Some researchers consider the present WHO recommendations of 450 µg Cd/week as far too high. It is also expressed that the present Cd-intake in Sweden of 10-15 µg Cd/capita,d will result in kidney damages to the most sensitive part of the population.

As a result of the concern over cadmium intake there is a general ban on cadmium and cadmium concentration in mineral fertilisers is limited to 100 mg Cd/kg P. A large producer of mineral fertilisers now markets a product with less then 5 mg Cd/kg P. As sludge has a cadmium level of 35-45 mg Cd/kg P it is argued that it is an inferior product. As can be seen from table 2 the acceptable annual load of cadmium on agricultural land is extremely low. Even if all 136 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna sewage sludge in Sweden, with it´s present quality, was spread on agricultural land for 100 years, the average soil cadmium level would not increase more than 1 %. This is, however, considered totally unacceptable by influential environmentalists, and especially the cereal industry is reluctant to accept crops grown on sludge amended soils. The reason is of course fear of public acceptance.

4.3 Other elements

Today the concentration and the application rates of seven metals are regulated. What other elements are present in sludge and may any of these elements be harmful? Such questions have often been raised recently and in order to provide better information, the National Swedish EPA and the Research Committee of the Swedish Water and Wastewater Works Assn (VAV) initiated a survey of the concentration of all metals and some other elements in Swedish sludges. The results (Eriksson 2001) show that for about half of the 61 elements investigated the levels in sludge are the same or lower than the levels in agricultural soils. For another quarter of the investigated elements, the concentrations in sludge is higher than in agricultural soils but sludge has to used more than 1000 years on the same soil in order to double the soil concentration. The concentrations in sludge and soil of elements, that have higher concentrations in sludge than in soil, are reproduced in table 5.

One of the official environmental goals of Sweden states that the concentration of elements in the environment shall be close to the natural background levels. With this in mind the elements listed in table 5 are problematic even if it is difficult to find any well-founded reason for concern.

4.4 Trace organic substances

The media image of WWTP and sludge consists of a picture where all the chemicals that are produced in “the chemical society” must end up somewhere and that place is the WWTP where it is concentrated in the sludge. When wastewater and sludge are characterised for trace organic and the concentration of most substances is found to be low or below the detection limit, the response is that only some hundreds of substances have been analysed for, while there are millions of possible compounds and even more possible metabolites and Peter Balmér 137 Sludge treatment and disposal strategies in Sweden degradation products not analysed for. In addition one of the national environmental goals is that substances of anthropogenic origin shall not be present in the environment or only present in negligible concentrations.

Table 5: Elements with sludge to soil concentration ratios over 2 (Eriksson 2001)

Element Median Median Sludge/soil-ratio concentration in concentration in sludge soil

mg/kg DS mg/kg DS

Ag 5.4 0.09 60 Au 0.57 <0.005 >100 B324.86.7 Bi 0.58 0.12 4.8 Cd 1.2 0.15 8 Hg 0.9 0.038 24 In 0.10 <0.04 >2 Mo 6.3 0.36 18 Pb 39 17 2.3 Pd 0.24 <0.04 >6 Ru 0.08 <0.04 >2 Sb 1.3 0.25 5.2 Se 1.8 0.21 8.6 Sn 20 1.4 14 U 8.1 3.5 2.3 W 3.5 1.3 2.7 Zn 500 67 7.5

Paxeus (1999) analysed wastewater from large and medium-sized WWTP:s and from small WWTP:s without industrial connections and found no large differences. He analysed for 263 substances, 87 were not detected or detected in concentrations below 0.1 µg/l. With the exception of substances, whose 138 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna presence is obvious, like fatty acids, koffein, nicotine, tensides and ftalates only a handful of substances were found in concentrations above 10 µg/l.

Brominated flame retardants came in focus in 1999 after a newspaper story. Although it soon became clear that sludge is a negligible route to the environment for brominated flame retardants and concentrations are low (VAV 2000) some environmentalists continue to use it as an argument against sludge.

Pharmaceuticals and oestrogenicis are substances that have attracted more and more interest during the last years. This has lead to that also the recycling of urine, that for several years has been advocated as a universal solution by influential groups, now is being questioned.

4.5 Sustainability

Sustainability is a main topic in the discussion of urban water and wastewater systems. The sustainability of our present systems is questioned. Wasting valuable resources, demanding too much capital, building up a future “mountain of maintenance” and dispersing of pollutants are criticisms often heard. On the other hand the water industry claims that our present system protects environment effectively and provides the urban population with a cost-efficient service. In order to resolve this controversy and to set the path for the future The Foundation for Strategic Environmental Research (MISTRA) has initiated a six-year research program now under way since two years (Malmquist 1999, Hellström et.al. 2000).

A major issue in the discussion on sustainability is the recycling of nutrients in food back to agricultural land. Phosphorus is an essential element for life and the known phosphorus resources are believed to be exhausted within 100-200 years. When phosphorus removal is employed in WWTP:s a substantial amount of the phosphorus removed from agricultural soil with crops can be recovered. Use of wastewater sludge in agriculture is the most apparent way to achieve this recirculation. However, the long-time sustainability of this option is questioned based on the metal content of sludge. Another option is to collect urine and or faecal matter separately. The different option will be evaluated in the MISTRA programme mentioned above. Peter Balmér 139 Sludge treatment and disposal strategies in Sweden

In a recent governmental paper it was proposed that 75 % of the phosphorus in wastes should be recovered before the year 2010. In Sweden the Kemira Company has developed a process (Krepro) for the extraction of phosphorus from sludge. So far there are no full scale installations of the Krepro-process. In Denmark a process for extraction of phosphorus from incinerated sludge ashes has been developed. It is interesting to note that these potential possibilities already has made environmental authorities to decide that, if incineration is employed, phosphorus should be extracted from sludge before or after incineration.

Most interest on resources has been on phosphorus. However, in a shorter time perspective the farming community seems to be more interested in nitrogen recycling due to expected increase in nitrogen prices.

5 Trends in sludge treatment technology

The Department of Environment of the Swedish government has requested the National Swedish EPA to review current regulations and to conduct an investigation in order to evaluate how in increased recirculation of phosphorus from wastes can be attained. The outcome of this is believed to determine, to a large degree, the future in sludge treatment and disposal.

As a regulation of the hygienic quality of sludge is one expected outcome it is believed that thermophilic digestion, pasteurisation, quick-lime additions or some other method for hygienisation will be part of the treatment scheme at plants that intend to utilise sludge on land. The Cambi process may also be a possibillity to achieve hygienisation and has been consideration for some plants.

The extraction of phosphorus from sludge is planned (but not decided) for the city of Malmö and the city of Falun has decided to incinerate the sludge and to extract phosphorus from the ashes. It is believed that other cities will await the experiences from these plants before considering any phosphorus extraction process.

Several municipalities consider incineration of sludge. VAV has made a preliminary study indicating that about seven regional incineration plants are 140 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna needed. However, the environmental authorities have so far been reluctant to incineration as long as it does not include a phosphorus recovery step. In Sweden a large part of the solid wastes are incinerated in incinerators with advanced flue gas treatment. An obvious solution could therefore be to co- incinerate sludge. However, from the year 2002 it will not be allowed to landfill combustible wastes and this will put such demand on incineration capacity that there will be very limited room for sludge. Incinerator capacity will probably be expanded and co-incineration cannot be ruled out.

As an alternative to incineration, one company in Sweden has started to market wet oxidation at supercritical conditions. So far only short term trials in pilot- scale has been conducted, but there is some interest in the technology, especially as it may be more suitable for smaller scales than conventional incineration.

Drying-pelletisation has attracted some interest as sludge pellets may be a suitable fertiliser in forestry. One plant has been built.

6 Trends in sludge disposal

The agricultural route is today not considered as reliable and landfilling of biodegradble organic wastes will be prohibited from 2005. All municipalities are today therefore trying to find alternatives to meet this situation. The results of the on-going regulation review at the National Swedish EPA as well as the revised EU Directive will have a large impact on preferred solutions.

Many alternatives are discussed and so far no clear preferences have emerged. Incineration with or without phosphorus recovery has been discussed above.

Whether the agricultural route will be used in the future or not will depend on how the agricultural-food industry complex appraise the image threat from known and unknown contaminants versus the will to demonstrate an attitude positive to recirculation of resources. The preference of local politicians, responsible for water and sewage, is to re-establish the agricultural route. Peter Balmér 141 Sludge treatment and disposal strategies in Sweden

In the present situation with so many insecurities interest is concentrated on solutions that are reliable for at least a number of years and not entailing too much investments. Solutions already used or under consideration are:

- the use of sludge or sludge mixtures as final top cover on landfills, as a considerable number of landfills will be closed down in the years to come due to the EU Landfill Directive

- the use of sludge as a soil substitute in urban areas and on golf courses and for similar purposes

- the production of a soil substitute from sludge and different admixtures

- dedicated land disposal.

Whether any of these alternatives also may be viable in a longer perspective depend tto a large degree on future regulations.

7 References

Balmér P (2001): Possibilities to improve the quality of wastewater sludges. Paper presented at the conf. “ Sludge management entering the 3rd millenium”, Taipeh 25-28 March 2001.

Hellström D, Jeppsson U and Kärrman E (2000): A framework for systems analysis of sustainable urban water management. Environmental Impact Assessment Review 20, 311-322.

Levlin E, Tideström H Kapilashrami S, Stark K and Hultman B (2001): Slamkvalitet och trender för slamhantering (Sludge quality and trends for sludge management) In Swedish.

VA-FORSK report, in press.

Malmquist P-A (2001): Sustainable urban water management – A Swedish national research programme. Presented at the Nordic Conference “Rensing av kommunalt spildevann”, Copenhagen 17-18 Feb 2001. To be published at www.vav.se. 142 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

Paxeus N (1999): Organiska för(or)eningar i avloppsvatten från kommunala reningsverk (Organic substances in wastewater from municipal wastewater treatment plants) In Swedish. VA-FORSK report 1999-1

VAV (Swedish Water and Wastewater Works Assn.) 2000, Bromerade flamskyddsmedel (PBDE och PBB) – ett problem? (Brominated flame retardants (PBDE and PBB) – a problem) In Swedish. VAV publication M113.

Sludge Handling Strategies in Denmark

S.E. Jepsen Danish Environmental Protection Agency, Denmark

1 Introduction

Denmark has a long tradition for utilizing the nutrients from sludge in agriculture. This tradition goes back to the collection of night soil in the cities, which was then utilized on the surrounding farmland. In the course of time the quality of the sludge deteriorated due to the extension of the sewer systems and the connection of waste water from more complex industrial productions together with the collection of sludge from domestic areas combined with the use of more complex products in the society in general. Therefore the recycling of sludge to agriculture more or less ceased in the 70’ties. In Denmark great efforts have been made over the last decades to regulate the discharge of toxic substances (heavy metals and organic micropollutans) to the sewer systems in order to improve the sludge quality. This has resulted in sludge of good quality and has increased the utilization of sludge in agriculture, reaching 70% in the mid 90’ties. Since then the recycling ratio has declined to around 60% due to new strict limit values for organic micropollutans in sludge.

2 Political Priorities

The overall political priority in Denmark is expressed through the Waste Action Plan (“Affald 21") adopted by the Danish Parliament. This plan gives the overall priorities for handling of all waste in accordance with the Waste Directive: 144 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

S Prevention S Recycling S Incineration with heat recovery S Landfilling

When it comes to handling sludge, it must be stressed that it is not possible to prevent the formation of sludge, considering the fact that the protection of the aquatic environment is given high priority as another important environmental goal.

Recycling of the nutrients in sludge as fertilizer in the agricultural production is given the highest political priority, mainly because phosphorous is a limited resource with around 100 years of supply left from known sources. Furthermore the import of P-fertiliser will introduce new heavy metals (especially cadmium) into Denmark, where sludge utilization can be seen as recycling of existing metals within the society. The nutrients cannot be exploited if the sludge is incinerated or dumped at landfills. For every kilogram of phosphorous “lost” with sludge that is incinerated or dumped at landfills one kilogram of P- fertiliser from virgin resources will be needed. This results in a production of approximately 18 kg waste per kg P (the so-called “ecological backpack”). To allow the sludge to be recycled in the agricultural production, the purity of the sludge has to be high both with respect to heavy metals as well as organic micropollutans, and also with respect to hygienic property in order to secure a humanly and environmentally safe use of the sludge. Sustainable sludge recycling is a matter of building up confidence among farmers, food industry, retailers and consumers.

Sludge, which is not suitable for land recycling due to the content of heavy metals or organic micropollutants, should be either incinerated or used in industrial productions, like cement industries or production of sandblast agent.

The Danish waste policy is supported by a waste taxation law, which put taxes on the least preferred disposal routes in order to promote the municipalities to recycle as much sludge as possible, and to put efforts into improving the quality of the sludge to extend the sludge recycling. The tax rates are described in Table 1 (all taxes are based on dewatered sludge). If sludge is dried before entering S.E. Jepsen 145 Sludge Handling Strategies in Denmark the incineration plant, the tax will be three times the weight to avoid construction of dryers, etc., and to avoid sludge treatment facilities being built just to save taxes. As can be seen the tax on landfilling is higher than for incineration in order to support the waste hierarchy.

Table 1: Waste Taxation in Denmark

Tax, DKK per ton Tax, approx. Euro per ton

Recycling 0 0 Incineration 330 44 Landfill 375 50

3 Danish Regulation of Sludge Recycling to Agriculture

In Denmark recycling of sludge to agriculture is regulated through a Statutory Order on utilization of waste products to agriculture/1/. This Order regulates all waste products suitable to utilization as fertilizer or soil improver, e.g. sludge, source separated organic householdwaste, sludge and waste from food industries, fermentation waste from biotechnological industries. The overall aim of the regulation is to set up minimum quality criteria to be met by all waste products with respect to heavy metals and organic micropollutants. In order to secure that all sludge used in agriculture fulfils the statutory order, the Order also sets up rules for application with maximum dosage of nutrient and dry matter and strict control patterns.

The limit values for heavy metals in the Danish Statutory Order are given in Table 2 together with the limit values of the existing EU Sludge Directive/2/ from 1986 and the proposed revised limit values indicated in the 3rd Draft of the Working Document on Sludge/3/, which indicates the future European regulation. 146 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

Table 2: Heavy Metal Limit Values in Denmark and EU

Heavy DK DK EU EU EU metal /1/ /1/ Directive Working- Working- /2/ paper/3/ paper/3/

Mg/kg DM Mg/kg P Mg/kg DM Mg/kg DM Mg/kg P

Cd 0.8 100 20 – 40 10 250

Cr 100 - - 1,000 25,000

Cu 1,000 - 1,000 – 1,000 25,000 1,750

Hg 0,8 200 16 – 25 10 250

Ni 30 2.500 300 – 400 300 7,500

Pb 120 10.000 750 – 1,200 750 18,750

Zn 4,000 - 2,500 – 2,500 62,500 4,000

The Danish limit values are much lower than the limit values in the 86 Directive, as well as the proposed future limit values (as can be seen from the table). The Danish limit values are set-up based on the precautional principle, focusing on long term protection of the agricultural soil. Microbiological diversity and the risk of up-take by plants are the main basis for the Danish limit values.

Besides heavy metals, the Danish regulation include limit values for four organic micropollutans. These limit values were decided in 1996 after a large survey/4/ on the occurrence and toxicity of a large number of micropollutans. In the study around 120 different micropollutants were measured in the sludge from 20 waste water treatment plants. The detected concentrations, combined with existing knowledge about the toxicity and fate of the micropollutants in the S.E. Jepsen 147 Sludge Handling Strategies in Denmark soil and the environment, led to limit values for four micropollutants that were found possibly could occur in concentrations close to the NOEC (no effect concentration) in soil or which could cause long-term effect. The four organic micropollutants regulated are:

S LAS: Anionic detergent (1,300 mg/kg DM) S Nonylphenols + nonylphenol with 1 and 2 ethoxylates: Non-ionic detergent (30 mg/kg DM) S DEHP: Plastisizer mainly in PVC (50 mg/kg DM) S Sum of PAH: 9 different PAH components, mainly from oil products and poor incineration (3 mg/kg DM)

Besides the quality demand in the form of limit values, the Statutory Order also includes requirements for control and sampling and rules of application. In general waste products shall be used as fertilizer in agriculture and according to the agronomic needs of the plants, in order to prevent pollution of the groundwater and surface water. Therefore the following maximum dosages of nutrients and dry matter are included in the Order:

S 210 kg Nitrogen per ha and year S 30 kg Phosphorous per ha and year (P can be dosed for three years) S 7 tons of dry matter per ha and year

The sludge has to be sampled and analysed by certified laboratories and the results are sent directly to the Plant Directorate, which controls that the quality is sufficiently high. This Directorate controls all other fertilizers as well, and thus farmers have high confidence in this control scheme (resulting in the sludge being sufficiently controlled). Finally the Order includes growth restrictions, depending on the treatment method (sanitized or stabilized) to protect from pathogenic microorganisms in the sludge. 148 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

4 Improvement of the Sludge Quality

The quality of the sludge has to be high in order to extend recycling of sludge to agriculture, and the content of heavy metals and organic micropollutants has to be as low as possible. In general three methods can be applied as tools to improve the sludge quality:

1. Removal of the toxic substances through removal from products, etc. (Substitution Strategy) 2. Control of the discharge from point sources and specific regulation and treatment of the point sources (Control Strategy) 3. Treatment and removal at the treatment plant (Treatment Strategy)

Normally a combination of the three methods will be necessary to retrieve a sludge quality of sufficiently high quality to be recommended as fertilizer in agriculture.

The most harmful substances have to be substituted from the products to avoid human exposure in general and to protect the environment. Specific control and discharge permits to the discharges of known toxic substances are efficient tools to improve the sludge quality, and can be applied for large industries as well as local dentists (for the removal of mercury).

The treatment possibility only exists if the toxic components that exceed the limit value are the organic micropollutants. In Danish investigations it has been shown that all the four organic micropollutants can be degraded if the sludge is post-treated under aerobic conditions, e.g. through composting.

5 Sludge Amounts in Denmark

In Figure 1 the development in amounts of sludge in Denmark from 1987 to 1999 is shown. From 1987 to 1994 the amounts of sludge in Denmark increased because the Danish waste water treatment plants were extended for nutrient removal, phosphorous as well as nitrogen, which results in larger sludge production per person equivalent connected. From 1994 until now the amount S.E. Jepsen 149 Sludge Handling Strategies in Denmark of sludge has been more or less stable with an annual production between 150,000 and 160,000 tons of dry matter per year. In the period from 1987 to 1995 the utilization of sludge in agriculture was increased from around 42% to 70%. This dramatic increase was achieved through great efforts by the Danish municipalities to improve the sludge quality through control of the discharge of heavy metals from the industrial point sources, combined with establishment of clear national rules for sludge utilization, including control of the quality of the sludge.

80 180000

70 160000

60 140000 120000 50 100000 40 80000

% of total 30 60000 20 40000 Tons Dry Matter pr. year 10 20000 0 0 1987 1994 1995 1996 1997 1998 1999

Agriculture Incineration Landfill Other Total (t DS/year)

Figure 1: Sludge Production and Sludge Handling in Denmark

Details of the sludge handling routes in 1999 are shown in Figure 2. Direct agricultural recycling accounts for around 57% (DM), and agricultural recycling after long-term storage for several years in reed bet mineralization plants accounts for 5% of the dry matter. Sludge in Denmark is typically dewatered to between 15 and 30% dry matter at the waste water treatment plant before final handling, but the biological mineralization plants receive the sludge with a dry matter content between 0,5 and 1%. This explains the differences between wet weight sludge and dry matter sludge in Figure 2. With the present sludge 150 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna utilization in agriculture approximately 3% of the Danish farmland is used for sludge application.

Industrial utilization of sludge in Denmark is a growing area. This is partly due to the fact that the dried sludge can be used in cement kilns, in which the inorganic part of the sludge is incorporated into the cement, and partly because a company in Denmark is planning a factory that shall produce sandblast agent, based on composted/mineralized sludge combined with other waste products.

50 Sludge in DM Sludge in WW 40

% of total sludge amount % 10

0 Agriculture Incineration Landfill Longtime Industrial storage utilisation

Figure 2: Sludge Handling Routes in Denmark in 1999

6 Sludge Quality

Sludge contains beneficial as well as problematic substances. The main beneficial component in sludge is the phosphorous content, but also the content of nitrogen, potassium and micro-nutrient are important. Besides the sludge has a liming effect. The average concentration of nutrients in Danish sludge is given in Table 3. S.E. Jepsen 151 Sludge Handling Strategies in Denmark

Table 3: Average Content of Nutrients in Danish Sludge

Nutrient Concentration Amount utilized in

kg/ton DM agriculture, 1999, tons

Phosphorous 3.1 2,500

Nitrogen 4.3 3,700

Potassium 3.2 174

Heavy metal concentration in sludge used for land application and that of all Danish sludge is given in Table 4. The Table shows that the efforts to improve the quality from 1987 to 1997 by lowering the content of heavy metals have been very effective, while no change can be detected from the last three years. It can also be seen that the quality of the sludge recycled as fertilizer in agriculture has a higher quality than the total sludge This is mainly due to the high concentration of heavy metals in the Copenhagen area, where the sludge is incinerated.

Table 4: Average Heavy Metal Concentrations in Danish Sludge in 1987, 1997 and 1999

Heavy 1987 1997 1999 Agric. 1999 metal mg/kg DM mg/kg DM mg/kg DM mg/kg DM

Cd 4.99 1.97 2.00 1.35 Cr 32.0 33.2 25.2 Cu 262 285 242 Hg 3.76 1.41 1.20 0.99 Ni 48.0 22.9 25.7 22.2 Pb 174 71.4 81.2 49.8 Zn 760 764 686 152 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

Concerning the the four organic micropollutants, the concentrations in the Danish sludge in 1997, 1998 and 1999 is given in Figure 3 to 6 as quantiles for all sludge.

140,0 NPE 120,0

100,0 1997 80,0 1998 60,0 1999 40,0

20,0

Concentration in mg/kg DM 0,0 0 102030405060708090100 % of sludge amount, all sludge

Figure 3: Concentration of Nonylphenols as Quantiles of all Sludge in 1997, 1998 and 1999

4.000 LAS 3.500

3.000

2.500 1997 2.000 1998 1999 1.500

1.000

500 Concentration in mg/kg DM 0 0 102030405060708090100 % of sludge amount, all sludge

Figure 4: Concentration of LAS as Quantiles of All Sludge in 1997, 1998 and 1999 S.E. Jepsen 153 Sludge Handling Strategies in Denmark

120,0 DEHP 100,0

80,0 1997 60,0 1998 1999 40,0

20,0 Concentration in mg/kg DM 0,0 0 102030405060708090100 % of sludge amount, all sludge

Figure 5: Concentration of DEHP as Quantiles of All Sludge in 1997, 1998 and 1999

7,0

6,0 PAH

5,0 1997 4,0 1998 3,0 1999

2,0

1,0 Concentration in mg/kg DM 0,0 0 102030405060708090100 % of sludge amount, all sludge

Figure 6: Concentration of 9 PAH as Quantiles of All Sludge in 1997, 1998 and 1999

From Figure 3 it can be seen that the content of nonylphenols have decreased especially from 1997 to 1998. This improvement of the sludge quality is expected to be a result of the voluntary agreement between the Ministry of Environment and the soap and detergent industry to cease the use of nonylphenolethoxylates in soap, washing powder and industrial cleaning agents, and to substitute the harmful detergents with other detergents which are more environmentally friendly. 154 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

Concerning the other three organic micropollutants, there is no clear development in the concentrations over the three years they have been measured regularly. As for heavy metals the quality of the part of the sludge that is used for agriculture is significantly higher than the quality of the remaining part. This is illustrated in Figure 7 with data for nonylphenol and nonylphenol with 1 and 2 ethoxylates.

80 NPE 70

50 Anaerobe 40

20 Aerobe 10

Concentration in mg/kg DM 0 0 102030405060708090100 % of sludge amount in DS, all sludge

Figure 7: Concentration of Nonylphenol as Quantile of Sludge Amount for All Sludge and Sludge Used in Agriculture in 1999

60 NPE 50

40 All sludge

20 Agriculture 10 Concentration in mg/kg DM 0 0 102030405060708090100 % of total sludge amount

Figure 8: Concentration of Nonylphenol as Quantile of Sludge Treated with Aerobic and Anaerobic Processes at the Waste Water Treatment Plant S.E. Jepsen 155 Sludge Handling Strategies in Denmark

The degradability of nonylphenol under aerobic- and anaerobic process conditions at the treatment plant is shown in Figure 8 as an example for the degradation of organic micropollutants. It can be seen that there is a clear difference in the quantile for anaerobic treated sludge and aerobic treated sludge, which clearly indicates that nonylphenols can be degraded aerobically. For LAS this difference is even clearer, while the differences for DEHP and the sum of PAH is less pronounced. For PAH other investigations have shown that only the PAH’s with three and four rings can be degraded within reasonable time.

7 Future Perspectives and Uncertainties

Sludge utilization in agriculture is an area in which it is essential that the necessary confidence among the different stakeholders is established. Sludge utilization is a long chain of stakeholders, which is no stronger than the weakest link. Therefore regularly and efficient control with the quality of the sludge and with the use of the sludge at the farmland are important tools to secure acceptance and confidence, not only among the farmers but also among the food producers, the retailers, the consumer associations and the consumers in order to maintain a common understanding that the use of sludge in agriculture is a sound and sustainable waste handling route.

Another important aspect of the long-term protection of agricultural recycling of sludge is the necessary openness among the central authorities to openly and actively investigate the realities behind new problems coming up in the public discussion. As an example bromated flame retardant were discussed in Denmark and besides the other problems with this agent, it was asked if the flame retardants would occur in sludge. As all substances used in the society more or less can be detected in sludge, bromated flame retardants could also be found. After an investigation of the concentrations in sludge and soil and an evaluation of potential human and environmental risks, it was concluded that the compounds should not be regulated in sludge because other ways of exposure were much more critical. The occurrence in sludge that is used in agriculture will not cause effect to the soil environment in the measured very low concentrations. Instead, the use of bromated flame retardants in the society 156 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna should be lowered and ceased if possible. Substitution of components like flame retardants has to be done internationally.

Public acceptance of sustainable recycling of nutrients from the waste products to agriculture requires that the regulation and handling of uncertainties is taken very serious, and a solution is based on the precautional principle. The Danish limit values for organic micropollutants can be seen as an example of this.

With a clear political priority promoting recycling of sludge to agriculture Denmark has been able to improve the sludge quality to an extent where a high recycling ratio of sludge could be maintained. Introduction of organic micropollutants in the Danish legislation have reduced the recycling, but it is expected that more than 50% of the sludge in the future will be able to meet with the strict quality criteria and will be utilized in agriculture.

8 References

/1/: The Danish Ministry of Environment and Energy. Statutory Order No. 49 of 20th January 2000 on Application of Waste Products for Agricultural Purposes (in Danish).

/2/: The EU Sludge Directive, Directive 86/278/EEC of 12th June 1986 on the Protection of the Environment and in Particular of the Soil, When Sewage Sludge is Used in Agriculture.

/3/: Working Document on Sludge, 3rd Draft, April 2000, ENV.E.3.

/4/: Danish Environmental Protection Agency, Environmental Project No. 366. (1997). Use of Waste Products in Agriculture.

Author: Svend-Erik Jepsen Danish Environment Protection Agency Strandgade 29 DK-104 Copenhagen e-mail: [email protected] 157 Wiener Mitteilungen (2001) Band 171, 157-166 Copyright © 2001; Institut für Wassergüte / TU-Wien

Sludge disposal management in the context of regional waste management (Zürich, CH)

T. Schmidt Amt für Abfall, Wasser, Energie und Luft, Zürich

Abstract: About 99 % of the 1.2 million inhabitants of the Canton of Zürich are connected to municipal wastewater treatment plants. The mechanical and biochemical wastewater treatment yields some 606‘000 m3 of sewage sludge per year, containing around 30'000 tons of dry solids (year 2000). Sewage sludge is defined by the corresponding laws as waste as well as recyclable fertilizer. Actually about 30 % of this sewage sludge is being used as agricultural fertilizer, 70 % are being incinerated or used as energy source for the cement production. A task of the cantonal administration is to provide a sustainable sewage sludge management as part of federal and cantonal waste management by applying federal laws. Although recovering nutrients, like phosphorus and nitrogen, for plant growth makes ecologically sense, more extensive discussions about the risks of using sewage sludge as fertilizer have increased since the beginning of the current year. Heavy metal-concentrations in sewage sludge are much lower than two decades ago due to wastewater pretreatment in industrial companies. But the effects of persistant organic pollutants or endocrinous substances are quite uncertain. The problem of the BSE (Bovine Spongiform Encephalopathy) has shown an especially stimulating effect on media and the public debate. A decreasing image of sewage sludge may cause a marketing-risk for farmers using this kind of fertilizer. The abolition of the agricultural use of sludge is considered as possible, the influence of consumer behaviour and the influence of big food distributors will probably be important on this matter. Loosing the option of agricultural use could be an opportunity for research of new ways of using the valuable substances present in sewage sludge.

Kurzfassung: Von den rund 1.2 Mio. Einwohnern des Kantons Zürich sind ca. 99 % an eine kommunale Abwasserreinigungsanlage angeschlossen. Die mechanische und biochemische Reinigung der entsprechenden Abwässer führt zu einer Klärschlammmenge von etwa 606'000 m3 pro Jahr, was ca. 30'000 Tonnen Trockensubstanz entspricht (Jahr 2000). Gemäss den entsprechenden Gesetzen hat Klärschlamm den rechtlichen Status als Abfall und als Abfalldünger. Gegenwärtig werden rund 30 % der jährlich anfallenden Klärschlammmenge landwirtschaftlich 158 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

verwertet, 70 % werden der Verbrennung zugeführt oder in der Zementindustrie als Brennstoff verwertet. Eine Aufgabe der kantonalen Verwaltung besteht darin, eine nachhaltige Klärschlammbewirtschaftung im Rahmen der Abfallwirtschaft zu gewährleisten, indem die Bundesgesetzgebung entsprechend umgesetzt wird. Obwohl die Rückgewinnung von Pflanzennährstoffen, wie Phosphor und Stickstoff, ökologisch sinnvoll ist, haben dieses Jahr die Diskussionen um Risiken der landwirtschaftlichen Klärschlammverwertung deutlich zugenommen. Die in Schlämmen festzustellenden Schwermetallkonzentrationen konnten dank Massnahmen in Industrie- und Gewerbebetrieben in den letzten beiden Dekaden deutlich gesenkt werden. Hingegen besteht Unsicherheit im Bezug auf Auswirkungen schwer abbaubarer organischer und endokriner Substanzen. Das Thema BSE (Bovine Spongiforme Enzephalopathie) hat sich im Rahmen der öffentlichen Debatte als besonders medienwirksam erwiesen. Ein sich verschlechterndes Image des Klärschlammes kann für Landwirte, welche ihn als Dünger einsetzen, zu einem eigentlichen Marktrisiko führen. Zur Zeit wird eine Abkehr von der Klärschlammdüngung für möglich gehalten, wobei der Einfluss seitens Konsumenten und Grossverteiler hierbei nicht zu unterschätzen ist. Der Wegfall der landwirtschaftlichen Klärschlammverwertung könnte stimulierend auf die Erforschung neuer Wege zur Nutzung der im Schlamm vorhandenen Wertstoffe wirken.

1 Management of waste and sludge in Switzerland

Situated in the center of Europe, Switzerland has got 7.123 million inhabitants, who live in an area of 41'285 km2. Water is a quite characteristic element of the alpine and pre-alpine landscapes, appearing as numerous rivers, brooks, lakes, glaciers and snowy peaks.

About 94% of Switzerland‘s inhabitants are connected to one of approx. 980 municipal wastewater treatment plants (WWTPs). The wastewater treatment yields about 4 million m3 of sewage sludge per year (1998), containing some 199'800 tons of dry solids (t DS). This amount is supposed to increase slightly up to about 210'000 t DS until 2005.

According to different corresponding federal laws, sewage sludge has got the legal position as waste as well as recyclable fertilizer. The most important related laws and decrees regulate the following issues:

S Protection of the environment (USG, 1983), T. Schmidt 159 Sludge disposal management in the context of regional waste management (Zürich, CH)

S Prevention of water pollution (GSchV, 1998), S Soil pollution (VBBo, 1998), S Ecologically hazardous substances (StoV, 1986/’92), S Waste management (TVA, 1990), S Application of fertilizers (DüV, DüBV, 2001).

Sewage sludge management responds to the priorities of Swiss waste management, which are:

1. Prevention 2. Reduction 3. Recycling 4. Sustainable disposal Actually sludge disposal takes place in the following way (1998):

S Incineration 81'555 t DS/y 41 % S Cement production 20‘481 t DS/y 10 % S Agriculture (liquid, dewatered, dried) 78'246 t DS/y 39 % S Composting 6'247 t DS/y 3 % S Disposal at a refuse disposal site (now forbidden) 3'276 t DS/y 7 % S Total 199'805 t DS/y 100%

According to the corresponding law (TVA, 1990) sewage sludge must be incinerated, if it can’t be reused (because of heavy metal concentrations above the limits, for instance). The option of sludge disposal in refuse disposal sites isn‘t allowed any more since 2000, but still practised because of lacking incineration capacities in some parts of Switzerland.

The advantage of agricultural use of sewage sludge consists in recycling substances, such as phosphorus, nitrogen, organic matter etc., for plant growth and enhancement of soil quality, corresponding to the principle of closed nutrient cycles. But, unfortunately, sewage sludge as well contains hazardous 160 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna substances. In order to limit their impact on agricultural soils, the following limits are defined (StoV):

S Maximum application of sludge: 5 t DS/ha*3 years S Limits (g/t DS) for concentrations of:

Pb 500 Cd 5 Cr 500 Co 60 Cu 600 Mo 20 Ni 80 Hg 5 Zn 2000 AOX (recommended) 500 S For epidemiological reasons, sludge applied on vegetable-growing and animal feed-growing areas must be pasteurized.

If spread sewage sludge showed concentrations around the valid limits, continuing with the sludge fertilization as nowadays still would be possible for about 80 years from now on, until agricultural soils would result over-polluted. Generally, actual concentrations lie clearly bellow the limits, at a level where agricultural soils supposingly bear the corresponding impact for about 200 years more.

Present contribution of sewage sludge on the total freight of substances, spread through all kind of fertilizers in Switzerland (per year, 1994/‘95): T. Schmidt 161 Sludge disposal management in the context of regional waste management (Zürich, CH)

element total fertilizers sewage sludge % of sewage sludge

P, 1'000 t/y 33.9 2.9 9 N, 1'000 t/y 208 4.8 2 Cd, t/y 0.91 0.22 24 Cr, t/y 86.2 8.7 10 Cu, t/y 157.7 41.1 26 Hg, t/y 6.1 0.21 3 Ni, t/y 25.2 3.8 15 Pb, t/y 38.1 15.9 42 Zn, t/y 678 132 19

The phosphorus contribution of sludge (2'900 t/y) comes to more than 30% of the amount contained in commercial fertilizers (7‘700 t/y). Although the entire phosphorus content of sludge is taken into account for nutrient balances, different research works have indicated, that according to the manner of phosphorus precipitation on WWTPs, 100 % of this nutrient may not always be disposable for plant growth.

Reusing sewage sludge as fertilizer also is of important concern to the prevention of water pollution: groundwater may show excessive nitrate concentrations, surface water stretches may receive overloads of nutrients like phosphorus and nitrogen, causing eutrophication.

Economic aspects: the agricultural use of sewage sludge (actually approx. 40% in whole Switzerland) helps to save disposal costs of about 23 million € per year. The fertilizer value of applied sludge is estimated on approx. 4 to 5 million €/y.

2 Sludge management in the Canton of Zürich

According to the Swiss political system, also waste management is caracterized by federal structures: the cantons are responsible to apply national law in their 162 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna areas. In order to exercise this task, cantons are authorized either to relax or to tighten federal laws when enacting cantonal laws and regulations.

2.1 Wastewater treatment and sludge production

With its approx. 1.2 million inhabitants, the Canton of Zürich is the most populated one in Switzerland. The capital, the City of Zürich and its surrounding communities form the biggest Swiss urban area, with approx. 1 million inhabitants.

Around 99 % of the inhabitants are connected to 77 municipal WWTPs, designed for more than 500 population equivalents (PE), and 36 municipal WWTPs for less than 500 PE. Furthermore there are 85 small private WWTPs in action. In the year 2000 about 260 million m3 of wastewater were treated, producing approx. 30'280 t DS of sewage sludge. This amount of sludge has been constant throughout the past years and won’t probably change a lot in the near future. Actually, about one third is being used as fertilizer, two thirds are incinerated or used in the cement production.

Sewage sludge disposal in the Canton of Zürich (year 2000):

S Incineration 8'650 t DS/y 29 % S Cement production 11‘330 t DS/y 37 % S Agriculture (liquid) 7'570 t DS/y 25 % S Agriculture (dewatered) 1'490 t DS/y 5 % S Agriculture (dried) 1'240 t DS/y 4 % S Total 30'280 t DS/y 100 %

During the first half of the 1990‘ies, about two thirds of the accumulated sludge were used as fertilizer in the agriculture. The reduction up to now is due to:

S The major part of farms have committed themselves to the norms of integrated/natural production, which entitles farmers to certain state subsidies; thus the control of applied fertilizers (prevention of excessive application of nutrients) has become stricter for these farms, T. Schmidt 163 Sludge disposal management in the context of regional waste management (Zürich, CH)

S The demand for compost has increased, S The image of sewage sludge has suffered from cases of misuse (excessive application, dubious business of certain sludge dealers).

2.2 The Sludge Management Plan (1995)

According to federal legislation, tha cantons have to provide a plan for sewage sludge management. The Sludge Management Plan was approved in 1995 by the cantonal government. Its two priorities are:

S The agricultural use for sludge of good quality (low heavy metal content in relation to the phosphorus content), if possible in areas/regions close to the producing WWTP, S A sustainable way of sludge disposal for 100 % of the sewage sludge produced in the Canton of Zürich, in case the agricultural option is not given: the so called 2nd Disposal Option (incineration, use as energy source for cement production).

The cantonal department for environmental protection (AWEL) is responsible for the WWTPs, and also for the sewage sludge management. In order to check the quantities of sludge used every year as fertilizer, the AWEL runs a phosphate balance (P2O5 spread as sludge and compost), containing data about origins and destinations of sludge deliveries. Based on these data, the departement of agriculture examines the correct application of fertilizers by farmers, which is a condition for receiving the corresponding state subsidies.

In order to ensure the 2nd sludge disposal option, every WWTP is assigned to an incineration plant (directly, or via dewatering/drying plants). Contracts between such sludge processing plants and the corresponding WWTPs guarantee the needed capacities and regulate the contributions of WWTP-holders to related inversions.

Typical costs for different ways of sludge disposal (not including costs for WWTP - internal sludge treatment, like pasteurization, digestion etc.): 164 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

S Direct delivery to farmers: 70 to 200 €/t DS (expenses for farmers) S Delivery via sludge dealers: 200 to 400 €/t DS S Incineration/cement production: 470 a 930 €/t DS

2.3 Current situation, debate about risks

The following aspects characterize the current situation of sludge management, as perceptible by the cantonal administration performing its corresponding tasks:

S For its quality, nearly 100 % of sewage sludge produced in the Canton of Zürich could be used as fertilizer. However, the current demand limits this option on about one third of the sludge to be disposed every year. Thus, WWTP-holders often find themselves forced to decide for the more expensive option of incineration or use as energy source in cement production. As part of municipal administrations, WWTP-holders may be under certain political pressure to reduce running costs, on the other hand some farmers don’t mind receiving the expences of 3 € up to 13 € per cubic metre of liquid sewage sludge for accepting this fertilizer. This difference of disposal costs, above mentioned, shows a stimulating effect on the (sometimes a bit mafia-like) activities of certain sludge dealers.

S Although the assignement of WWTPs to sludge treatment plants in order to assure capacities for incineration / cement production for 100 % of the sewage sludge is generally accepted, some WWTP-holders showed a certain resistance: they asserted the laws of free trade to be applied as well on the sector of disposal (some incineration plants out of the Canton of Zürich offer their services for lower prices).

S Exercising the tasks related to sludge management, the AWEL often faces the dilemma between ecological goals (sludge disposal in the region of the producing WWTP, to keep transportation distances short) and principles of the free trade (the liberty of consumers to decide for products, no matter where they are produced, should be applied on the disposal sector as well). T. Schmidt 165 Sludge disposal management in the context of regional waste management (Zürich, CH)

S Since the beginning of the current year, discussions about the risks of using sewage sludge as fertilizer have increased. Whereas heavy metal- concentrations are much lower than two decades ago, due to measures of wastewater-pretreatment in industrial enterprises, there is much uncertainty about the effects of persistant organic pollutants or endocrinous substances. The problem of BSE has shown an especially activating effect on media and the public debate. There isn’t yet secured knowledge about BSE-infection risks related to agricultural use of sludge, the probability is considered as low. Anyway the state administration recommended to take measures of prevention, like stopping to use sludge from WWTPs as fertilizer, if for instance the wastewater of big slaughterhouses etc. is treated there.

3 Future prospects, conclusions

Actually it’s difficult to predict the short- or medium-term development of sewage sludge disposal options. Different signals though suggest, that an abolition of the agricultural use of sludge could happen soon:

S Several agricultural associations are demanding the prohibition of agricultural use by the public administration,

S Two big food distributors have already prohibited the use of sludge for certain (ecological) label products to their contracted farmers,

S Sewage sludge as an „end of pipe-product“ is probably suffering a loss of image because of the current debate. Thus farmers using sludge, face another kind of risk, the ‚marketing risk‘: Consumers may avoid to buy agricultural products, having been fertilized with sewage sludge.

In Switzerland, as in the EU, the present discussion shows two opposing points of view:

S To avoid ecological, epidemiological and marketing risks, the agricultural use of sludge should be abolished, 166 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

S In order to spare limited natural resources as phosphorus, sludge recycling makes sense.

However, an abolition of agricultural use of sewage sludge at short-term is considered as possible. Among cantonal (environmental) administrations, intentions to improve the inter-cantonal cooperation of waste-, and particularly sludge- management have been manifested. On behalf of the federal administration, actually a study about the risks of using recyclable fertilizers is being elaborated. The publication is planned for mid-September of the current year. Results probably won’t lead to a legal prohibition of sewage sludge for agricultural use, but rather to recommendations for cautious sludge diposal management.

Consumer behaviour and the big food distributors will probably have a crucial influence on the future acceptance of sludge as a fertilizer.

Although disposal costs would increase in case of abolishing the agricultural option, in the long-term sludge disposal (including treatment) probably would become more economical: incineration plants would work at a more optimal capacity level, and WWTP - internal sludge treatment, such as pasteurization, would become unnecessary.

An abolition of agricutural use of sewage sludge could be an opportunity to stimulate further re-search activities, not only in order to improve and optimize the efficiency of incineration plants, but to develop methods and technologies of reusing valuable substances contained in sludge, such as phosphorus and nitrogen.

Author: Thomas Schmidt AWEL – Amt für Abfall, Wasser, Energie und Luft Abt. Gewässerschutz Hadturmstrasse 104 CH-8005 Zürich e-mail: [email protected] 167 Wiener Mitteilungen (2001) Band 171, 167-180 Copyright © 2001; Institut für Wassergüte / TU-Wien

Soil protection aspects of sludge application in agriculture

M. Pollak wpa consulting engineers, Vienna

Soil protection aspects of sludge application in agriculture

Michael Pollak wpa consulting engineers gmbh, Vienna [email protected] 168 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

Soil protection aspects of sludge application in agriculture

soil protection - soil functions

criteria for sustainable soil use

special criteria for reuse of organic waste

examples and results

sustainable soil protection

• Maintenance of ecological functions and functions related to human health, human activity, groundwater protection and food production

• Protection and preservation of a finite, scarce and non-renewable resource with varying biological, chemical and physical properties

Special emphasis should be given to time and space variability; limited resilience. M. Pollak 169 Soil protection aspects of sludge application in agriculture

main soil functions

ecological socio-economical

• production of • source of raw biomass materials • filter, buffer and • infrastructural basis transformation • geogenic and • biological habitat, cultural heritage gene reserve

criteria for sustainable soil use

• prevention of irreversible soil loss and soil degradation

– consideration of site-related soil potentials

– use of best available technologies and practice 170 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

criteria for agricultural use of organic waste (sewage sludge, compost ...)

• quality criteria: ( agricultural benefits ( ecological improvement • quality insurance ( periodical determination and of nutrients and PTEs improvement : ( monitoring of PTEs (type and limit-values) to the state of knowledge ( source-orientated reduction concepts

PTEs = potentially toxic elements

First point: key justifications! not yet regulated ; existing quality criteria mainly deal with PTEs and thresholdlimits;

For instance a definition of minimum-concentrations for nutrients (e.g. phosphorus) in sludge; ecological improvement also takes into account related effects such as minimizing transport, building up of a “sludge (waste)-consciousness”; accepting recycle strategies instead of linear material fluxes; reduced demand of non-renewable materials (e.g. apatite) and energy; M. Pollak 171 Soil protection aspects of sludge application in agriculture

agricultural benefits

2t dm of sludge per ha and year providing:

• fertilizing effects P2O5 (P,N) Nt • soil improvement (CaO, OM) CaO OM 10 100 1000 kg/ha

Graph: 25 to 75 percentile from 300 municipial sewage sludges from Lower Austria (1994 to 2001)

ecological improvement

mineral fertilizers sewage sludge

Cd Cd

P2O5 P2O5

0.1 1 10 100 1000 10000 100000 0.1 1 10 100 1000 10000 Mg per year Mg per year 172 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

Austria (1999) uses about 48.000 Mg of P2O5 from mineral fertilizers; which is equivalent to 1,2 Mg Cd net-import to Austria; (average Cd-Content is 25mg

Cd/kg P2O5;) On the other hand Austria produces about 200.000 Mg dm of sewage sludge with 2,8 - 5,6% P2O5 potentially äquivalent to 5.600 - 11.200 Mg P2O5 (12 to

23% of total P2O5) and 190 - 380 kg Cd; (16 to 32% of Cd-Import) (25 - 75% percentile from 400 municipial sludges (Lower Austria) = 22 - 46mg

Cd/kg P2O5; mean = 34mg Cd/kg P2O5);

ecological improvement

1300 1

1250 1200 1200 0,91 0.9 1150

1100 0,86

1050 kg Cd per year per kg Cd 0.8 g Cd per ha and g Cd per ha year and 1000 990 950

900 0.7 without with reuse of sewage sludge

Reuse of 200.000t dm of sewage sludge with an average P2O5-content of 4,2% and an average Cd-content of 34mg Cd per kg P2O5 would have the following effects: - decrease of Cd net-import from 1200kg to 990kg per year - increase of Cd-load per hectar and year from 0,857g to 0,911g

Germany: BBSchG:allowable additional load per year (zulässige Zusatzfracht): 6g Cd ; where 3g per ha could be “used” for agricultural imissions; M. Pollak 173 Soil protection aspects of sludge application in agriculture

quality insurance 1994 - 2000

(concentrations related to %P2O5)* Hg Cd Ni Pb Cr Cu Zn

0 20 40 60 80 100 120 % of limit value (Class II) *data from waste water treatment plant Amstetten, Lower Austria

Ranges of heavy metal concentrations of sewage sludge of the Amstetten wastewater treatment plant (1994 to 2000, 4 analyses/year).

** quality-class II and III * mean of 398 analyses 1994-2001, Lower Austria; standardized to 10% CaO

Lower mg/kg dm 86/278/EEC Average* Austria** Cd 20 – 40 2 – 8 1,4 Cr - 50 – 500 45 Cu 1000 – 1750 300 – 500 206 Hg 16 – 25 2 - 8 1,4 Ni 300 – 400 25 – 100 27 Pb 750 – 1200 100 – 400 59 Zn 2500 – 4000 1500 – 2000 845 Co - 10 – 100 4,8 AOX - 500 218 PCB(6) - each<0,2 0,02 PCDD/PCDF - 100ngTE 13 174 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

quality improvement

175 Cd 150 5

O 125 2

100

75 mg Cd/ kg P

0 93 94 95 97 98 99 01 02

398 sludge analyses from 103 treatment plants1994 - 2001, Lower Austria

A slight decreasing trend can be detected, which is due to 2 effects: - increase in phosphorus-content because of now obligible phosphorus elimination - source oriented reduction/avoidance because of new emission-standards for industries and small enterprises (IndirekteinleiterVO) M. Pollak 175 Soil protection aspects of sludge application in agriculture

monitoring 1.2

1.0

0.8

0.6

0.4 mg Cd / kg Boden Cd / kg mg

0.2

0.0 Erst- Wiederholungs- untersuchung

Cd- concentrations in upper soil layers before (Erst-) and after (Wiederholungsuntersuchung) 6 years of sludge application (2 Mg/ha and year)

monitoring

0.2

0.1

-0.1

-0.2 r = -0,071

-0.3 Change of concentration of Change dm soil in mg/kg 0 10 20 30

Cd-load from sewage sludge (g/ha)

70 plots with 6years sewage sludge application (average 2 Mg dm/year). 176 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

Concentrations in soil-depth 0 - 20 cm; data show no evidence Cd-increase due to sludge application.

monitoring

atm. Dep. 9 %

min. fertilizers 12 % sewage sludge 38 %

manure 41 %

Cd Input; average for 70 plots

Different Cd-sources for 70 agricultural plots. M. Pollak 177 Soil protection aspects of sludge application in agriculture

monitoring

120

100

60 manure 40 min. fertilizers

Cd input in g/ha Cd input 20 sewage sludge 0 1 3 4 5 6 9 10 11 12 13 14 farm

Different Cd-sources for 14 farms.

monitoring of PTEs

• Organic pollutants like PCDD/Fs or PCB range within background • evaluation of toxicological significance of surface active agents (LAS, NP) and plasticizers (DEHP) 178 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

DEHP = Di(2-ethyl-hexyl-phthalate) LAS = Linear Alkyl Benzol Sulfonate NP = Nonylphenol

source orientated concepts

20 18 16 14 additional Cu- 12 load 10 8 6

Cu in g/PE.a 4 2 bottle- yeast- sediments ? erosion- Soil sediments ? 0 cleaning Cu- pesticides harvest wine treatments 8.2.96 4.3.96 18.4.96 15.5.96 30.6.96 31.7.96 29.8.96 24.9.96 23.10.96 19.11.96

Data from waste water treatment plant Wagram West, Lower Austria

Additional Cu-load to the waste water treatment plant due to wine production. M. Pollak 179 Soil protection aspects of sludge application in agriculture

source orientated concepts

250

200

150 Cu Linear (Cu) 100 % of class II class % of 50

0 4 4 5 5 5 5 6 7 7 9 9 9 9 9 9 9 9 9 ______5 6 4 8 0 0 9 3 4 1 1

Cu-concentration of municipial sewage sludge in a wine-growing region; decrease as an effect of the information an controlling campaign.

source orientated concepts

1600

Cu 1200

Hg 800 400 mg/kg dm 0 before after dentist 180 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

Cu and Hg concentrations in the sewer sediment before an after the inflow of a dentist‘s wastewater.

summary agricultural (re)use of sewage sludge/organic waste-products requires best qualities and special regard to: • site conditions • varying composition • nutrient-oriented loads • application standards/BAT • monitoring • further quality improvement

Detailed information resp. references on special topics to be requested from the author.

Authors: DI Michael Pollak wpa consulting engineers gmbh Lackierergasse 1 / 4 A -1090 Wien e-mail: [email protected] 181 Wiener Mitteilungen (2001) Band 171, 181-184 Copyright © 2001; Institut für Wassergüte / TU-Wien

Conclusions from the EWA/ÖWAV Workshop on Sludge Disposal

H. Kroiss Vienna University of Technology

Every sludge disposal option has to be reliable for the treatment plant operator at any time as sludge is a necessary by-product fulfilling the legal requirements for waste water treatment.

If a disposal option is not reliable over a long period (15 to 20 years) different options have to be provided simultaneously As a consequence investments for adequate sludge treatment and disposal facilities will markedly increase.

Costs for different sludge treatment and disposal options strongly depend on the size and the regional context of the treatment plants.

In the context of regional material fluxes sewage sludge has a low resource potential and a low pollution potential despite the fact that it can be characterised as a sink, concentrating the waste water compounds.

Mass flow of nutrients (N, P) in the sewage sludge is comparatively small as compared to the losses of nutrients from agriculture.

The most valuable element in the sludge is phosphorus. as the availability of phosphorus minerals for the production of low cost market fertiliser is limited. Up to 90% of the phosphorus of the waste water can be recovered in the sludge at relatively low costs. The easiest way of P-recycling is agricultural sludge application.

The recovery of phosphorus from the sludge is the topic of international research. Sludge incineration does not inhibit P recovery in the future. P recovery from the sludge is a technological (organic matrix, iron) and an economic problem. 182 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

Nitrogen contained in sewage sludge is normally low as compared to the nitrogen flow in the waste water and very low as compared to the losses of nitrogen from agriculture. Nitrogen is not a limited resource. Nitrogen contained in the sludge is important if sludge is put to landfill as it will result in long-term ammonia leaching.

Organic matter of the sludge is very low as compared to the organic material flows in agriculture. The value of the organic material in the sludge can only play a local role mainly in hot arid climates.

Agricultural use of sewage sludge can be seen as the option with the lowest “loss” of valuable compounds of the sludge, especially phosphorus, and the lowest increase of entropy. The reliability of this disposal route for the treatment plant operator depends on several major pre-requisites:

S Reliability in regard to hygiene S Reliability in regard to long-term soil protection S Public acceptance (politicians, media) S Acceptance by all stakeholders involved in sludge application and its consequences (farmers, farmer unions, land owners, food industry, food trade, retailers, consumers, consumer associations, NGOs, etc.)

The first two prerequisites can be based on scientific research and risk assessment. As a consequence only for these two aspects quality criteria and adequate procedures can be developed and introduced into a legal framework and quality assurance procedures. The other two have to be tackled by sociology, psychology and political science and have a strong educational aspect.

The rate of sludge application in agriculture (t/ha/a) is normally limited by the P-requirements of the agricultural soils. Therefore a relation of the heavy metal limit concentrations to the P-content of the sludge is reasonable for soil protection considerations.

As long as sludge is a “waste” and “waste” is linked with negative aspects in public opinion it will be difficult to convince all people that agricultural use of H. Kroiss 183 Conclusions from the EWA/ÖWAV Workshop on Sludge Disposal sludge is a sustainable way of disposal. The connotation of “waste” and “hazard” has a reasonable educational aspect, this has to be kept in mind.

Practical experience with sludge disposal is different in different European countries (S, DK, G, F, CH):

S Different countries have developed different strategies and have changed their strategy during the last decade

S Policy aspects as decision making procedures and continuity in political strategy play a key role in all the countries. There is also a strong relation between these political factors and the costs for sludge disposal and the preferred disposal route.

S Even very elaborated legal frameworks with very stringent quality criteria can have detrimental effects on agricultural use of sludge if they are not based on consensus and confidence of all parties involved.

S A comprehensive legal framework for soil protection including all materials applied on land seems to be much more efficient in regard to sludge recycling than separate requirements for sewage sludge, mineral fertiliser, manure, compost etc.

S Hygienic problems with controlled sewage sludge application in agriculture are much less with application on arable land than on grass land. Even for the application on arable land the salmonella problem could need special attention. BSE and MFD seem not to represent an elevated hygienic risk.

S For large treatment plants in agglomerations (e.g. > 1 Mio. PE) raw sludge incineration with ash disposal can be an economic and ecologically sound solution.

S The development of low cost small incineration plants (for digested sludge) meeting advanced off gas standards is in progress.

S Co-incineration of digested sludge with cement and solid waste can result in economically sound solutions. In regard to P-recovery it does not represent a sustainable solution. 184 Sewage Sludge Disposal – Sustainable and/or reliable solutions EWA - Workshop 2001, Vienna

S For the very large number of small treatment plants (e.g. <20.000 PE) agricultural use of sewage sludge seems to be the most economic and sustainable solution as long as source abatement of possibly hazardous substances is successful.

S The concentrations of heavy metals and other hazardous substances in most of the sewage sludges in the countries with a high standard of source control are in the same range and far below the current European standards. These concentrations are excellent indicators for the progress in water protection by source control. Sludge analysis remains an important monitoring tool for source control even if the sludge is not used in agriculture or on soils.

S Sludge disposal of dewatered sludge in landfills should be avoided as it results in long term monitoring requirements especially for ammonia leaching.

S Changes in sludge disposal technology need time for the adaptation process which often exceeds several years (design, permit procedure, construction) while sludge production can not be stopped. This message has to be transported to the political decision makers.

Author: o.Univ.Prof. Dipl.Ing. Dr. Helmut Kroiß Institute for Water Quality & Waste Management Vienna University of Technology Karlsplatz 13/226 A-1040 Vienna e-mail: [email protected] Band Nr Preis €

WIENER MITTEILUNGEN WASSER • ABWASSER • GEWÄSSER

Eine von den Wasserbauinstituten an der Technischen Universität Wien, den Instituten für Wasserwirtschaft der Universität für Bodenkultur und dem Österreichischen Wasser- und Abfallwirtschaftsverband herausgegebene Schriftenreihe

Band Nr Preis € 1 Das Wasser (1968) Kresser W. vergriffen

2 Die Gesetzmäßigkeiten der stationären Flüssigkeitsströmung durch gleichförmig rotierende zylindrische Rohre (1968) Breiner, H. vergriffen

3 Abwasserreinigung - Grundkurs (1969) von der Emde, W. vergriffen

4 Abwasserreinigungsanlagen - Entwurf-Bau-Betrieb (1969) 4. ÖWWV-Seminar, Raach 1969 vergriffen

5 Zukunftsprobleme der Trinkwasserversorgung (1970) 5. ÖWWV-Seminar, Raach 1970 vergriffen

6 Industrieabwässer (1971) 6. ÖWWV-Seminar, Raach 1971 vergriffen

7 Wasser- und Abfallwirtschaft (1972) 7. ÖWWV-Seminar, Raach 1972 vergriffen

8 Das vollkommene Peilrohr (Zur Methodik der Grundwasserbeobachtung) (1972) Schmidt, F. vergriffen

9 Über die Anwendung von radioaktiven Tracern in der Hydrologie (1972) Pruzsinsky, W. Über die Auswertung von Abflußmengen auf elektronischen Rechenanlagen Doleisch, M.: 18

10 1. Hydrologie-Fortbildungskurs (1972) vergriffen

Anhang I Band Nr Preis €

11 Vergleichende Untersuchungen zur Berechnung von HW-Abflüssen aus kleinen Einzugsgebieten (1972) Gutknecht, D. vergriffen

12 Uferfiltrat und Grundwasseranreicherung (1973) 8. ÖWWV-Seminar, Raach 1973 vergriffen

13 Zellstoffabwässer-Anfall und Reinigung (1972) von der Emde W., Fleckseder H., Huber L.,Viehl K. vergriffen

14 Abfluß - Geschiebe (1973) 2. Hydrologie-Fortbildungskurs 1973 vergriffen

15 Neue Entwicklung in der Abwassertechnik (1983) 9. ÖWWV-Seminar, Raach 1974 vergriffen

16 Praktikum der Kläranlagentechnik (1974) von der Emde W. vergriffen

17 Stabilitätsuntersuchung von Abflußprofilen mittels hydraulischer Methoden und Trendanalyse (1974) Behr, O.: 18

18 Hydrologische Grundlagen zur Speicherbemessung(1975) 3. Hydrologie-Fortbildungskurs 1975 vergriffen

19 Vorhersagen in der Wasserwirtschaft (1976) 1. Hydrologisches Seminar des ÖWWV 1976 10

20 Abfall- und Schlammbehandlung aus wasserwirtschaftlicher Sicht (1976) 11. ÖWWV-Seminar, Raach 1976 vergriffen

21 Zur Theorie und Praxis der Speicherwirtschaft (1977) 2. Hydrologisches Seminar des ÖWWV 1977 22

22 Abwasserreinigung in kleineren Verhältnissen (1977) 12. ÖWWV-Seminar, Raach 1977 vergriffen

23 Methoden zur rechnerischen Behandlung von Grundwasserleitern (1977) Baron W., Heindl W., Behr O., Reitinger J. vergriffen

24 Ein Beitrag zur Reinigung des Abwassers eines Chemiefaserwerkes, eines chemischen Betriebes und einer Molkerei (1978) Begert A. vergriffen

Anhang II Band Nr Preis €

25 Ein Beitrag zur Reinigung von Zuckerfabrikabwaser (1978) Kroiss H. vergriffen

26 Methoden der hydrologischen Kurzfirstvorhersage (1978) Gutknecht D. vergriffen

27 Wasserversorgung-Gewässerschutz (1978) 13. ÖWWV-Seminar, Raach 1978 vergriffen

28 Industrieabwasserbehandlung - Neue Entwicklungen (1979) 14. ÖWWV-Seminar, Raach 1979 vergriffen

29 Probleme der Uferfiltration und Grundwasseranreicherung mit besonderer Berücksichtigung des Wiener Raumes (1979) Frischherz H. vergriffen

30 Beiträge zur Hydraulik, Gewässerkunde und Wasserwirtschaft (1979) o. Univ.-Prof. DDr. Werner Kresser zum 60. Geburtstag vergriffen

31 Grundwasserzuströmungsverhältnisse zu Horizontalfilterrohrbrunnen (1980) Schügerl W. vergriffen

32 Grundwasserwirtschaft (1980) 3. Hydrologisches Seminar des ÖWWV 1980 25

33 Kulturtechnik und Wasserwirtschaft heute (1) (1980) vergriffen

34 Behandlung und Beseitigung kommunaler und industrieller Schlämme (1980) 15. ÖWWV-Seminar, Raach 1980 vergriffen

35 Faktoren, die die Inaktivierung von Viren beim Belebungsverfahren beeinflussen (1980) Usrael G. vergriffen

36 Vergleichende Kostenuntersuchungen über das Belebungsverfahren (1980) Flögl W. vergriffen

37 Ein Beitrag zur Reinigung und Geruchsfreimachung von Abwasser aus Tierkörperverwertungsanstalten (1980) Ruider E. vergriffen

38 Wasserwirtschaftliche Probleme der Elektrizitätserzeugung (1981) Schiller, G.: vergriffen

Anhang III Band Nr Preis €

39 Kulturtechnik und Wasserwirtschaft heute (1981) Teil 2 vergriffen

40 Wasseraufbereitung und Abwasserreinigung als zusammengehörige Techniken (1981) 16. ÖWWV-Seminar, Raach 1981 vergriffen

41 Filterbrunnen zur Erschließung von Grundwasser (1981) ÖWWV-Fortbildungskurs 1981 29

42 Zur Ermittlung von Bemessungshochwässern im Wasserbau (1981) Kirnbauer R. 22

43 Wissenschaftliche Arbeiten, Zeitraum 1977 bis 1981 (1981) 25

44 Kulturtechnik und Wasserwirtschaft - heute (1981) Teil 3 25

45 Verbundwirtschaft in der Wasserversorgung (1982) ÖWWV-Fortbildungskurs 1982 29

46 Gewässerschutzplanung, deren Umsetzung und Zielkontrolle im Einzugsgebiet des Neusiedler Sees (1982) Stalzer W. vergriffen

47 Wechselwirkung zwischen Planung und Betrieb von Abwasserreinigungsanlagen, Erfahrungen und Probleme (1982) 17. ÖWWV-Seminar, Ottenstein 1982 vergriffen

48 Kleinwasserkraftwerke - Notwendigkeit und Bedeutung (1982) Flußstudien: Schwarza, kleine Ybbs, Saalach vergriffen

49 Beiträge zur Wasserversorgung, Abwasserreinigung, Gewässerschutz und Abfallwirtschaft (1982) o. Univ.-Prof. Dr.-Ing. W. v.d. Emde zum 60. Geburtstag vergriffen

50 Kulturtechnik und Wasserwirtschaft - heute (1982) Teil 4 vergriffen

51 Sicherung der Wasserversorgung in der Zukunft (1983) 18. ÖWWV-Seminar, Ottenstein 1983 vergriffen

52 Thermische Beeinflussung des Grundwassers (1983) ÖWWV-Fortbildungskurs, 1983 vergriffen

Anhang IV Band Nr Preis €

53 Planung und Betrieb von Regenentlastungsanlagen (1984) ÖWWV-Fortbildungskurs, 1984 vergriffen

54 Sonderabfall und Gewässerschutz (1984) 19. ÖWWV-Seminar, Gmunden 1984 vergriffen

55 Naturnahes Regulierungskonzept "Pram" (1984) 26

56 Blähschlamm beim Belebungsverfahren (1985) ÖWWV-Fortbildungskurs, 1985 vergriffen

57 Chemie in der Wassergütewirtschaft (1985) ÖWWV-Fortbildungskurs, 1985 vergriffen

58 Klärschlamm - Verwertung und Ablagerung (1985) 20. ÖWWV-Seminar, Ottenstein 1985 vergriffen

59 Wasserkraftnutzung an der Thaya (1985) Pelikan B. 23

60 Seminar "Wasser - Umwelt - Raumordnung" (1985) 16

61 Gewässerschutz im Wandel der Zeit Ziele und Maßnahmen zu ihrer Verwirklichung (1985) Fleckseder, H. vergriffen

62 Anaerobe Abwasserreinigung (1985) Kroiss H. vergriffen

63 Kleine Belebungsanlagen mit einem Anschlußwert bis 500 Einwohnergleichwerte (1985) Begert A. vergriffen

64 Belüftungssysteme beim Belebungsverfahren (1986) ÖWWV-Fortbildungskurs, 1986 vergriffen

65 Planung und Betrieb von Behandlungsanlagen für Industrieabwässer (1986) 21. ÖWWV-Seminar, Ottenstein 1986 vergriffen

66 Ausspracheseminar Grundwasserschutz in Österreich (1986) ÖWWV-Fortbildungskurs, 1986 29

67 Kulturtechnik und Wasserwirtschaft heute (5) (1986) vergriffen

Anhang V Band Nr Preis €

68 Zur mathematischen Modellierung der Abflußentstehung an Hängen (1986) Schmid B.H. 22

69 Nitrifikation - Denitrifikation (1987) ÖWWV-Fortbildungskurs, 1987 vergriffen

70 Flußbau und Fischerei (1987) vergriffen

71 Wasserversorgungung und Abwasserreinigung in kleinen Verhältnissen (1987) 22. ÖWWV-Seminar, Ottenstein 1987 vergriffen

72 Wasserwirtschaft und Lebensschutz (1987) Wurzer E. vergriffen

73 Anaerobe Abwasserreinigung Grundlagen und großtechnische Erfahrung (1988) ÖWWV-Fortbildungskurs, 1988 vergriffen

74 Wasserbau und Wasserwirtschaft im Alpenraum aus historischer Sicht (1988) 22

75 Wechselbeziehungen zwischen Land-, Forst und Wasserwirtschaft (1988) ÖWWV-Fortbildungskurs, 1988 vergriffen

76 Gefährdung des Grundwassers durch Altlasten (1988) 23. ÖWWV-Seminar, Ottenstein 1988 vergriffen

77 Kulturtechnik und Wasserwirtschaft heute (6) (1987) vergriffen

78 Wasserwirtschaftliche Planung bei mehrfacher Zielsetzung (1988) Nachtnebel, H.P. 25

79 Hydraulik offener Gerinne (1989) Symposium, 1989 vergriffen

80 Untersuchung der Fischaufstiegshilfe bei der Stauhaltung im Gießgang Greifenstein (1988) Jungwirth M., Schmutz S. vergriffen

81 Biologische Abwasserreinigung (1989) ÖWWV-Fortbildungskurs, 1989, TU-Wien vergriffen

82 Klärschlammentsorgung (1989) 24. ÖWWV-Seminar, Ottenstein 1989 vergriffen

Anhang VI Band Nr Preis €

83 Viruskontamination der Umwelt und Verfahren der Kontrolle (1990) 2. Symposium 18

84 Schadstofffragen in der Wasserwirtschaft (1989) ÖWWV-Fortbildungskurs 1989, TU-Wien 29

85 Schlußbericht zum Forschungsvorhaben Trinkwasseraufbereitung mit Ultraschall, Projekt Abschnitt I (1989) Frischherz H.; Benes E.; Ernst J.; Haber F.; Stuckart W. 18

86 Umfassende Betrachtung der Erosions- und Sedimentationsproblematik (1989) Summer W. 25

87 Großräumige Lösungen in der Wasserversorgung (1990) 25. ÖWWV-Seminar, Ottenstein 1990 vergriffen

88 Revitalisierung von Fließgewässern (1990) Beiträge zum Workshop Scharfling, 1989 vergriffen

89 Kulturtechnik und Wasserwirtschaft heute (1990) Teil 9 vergriffen

90 A Study on Kinematic Cascades (1990) Schmid B.H. 18

91 Snowmelt Simulation in Rugged Terrain - The Gap Between Point and Catchment Scale Approaches (1990) Blöschl G. 18

92 Dateninterpretation und ihre Bedeutung für Grundwasserströmungsmodelle (1990) Blaschke A.P. nicht erschienen

93 Decision Support Systeme für die Grundwasserwirtschaft unter Verwendung geografischer Informationssysteme (1990) Fürst J. 18

94 Schlußbericht zum Forschungsvorhaben Trinkwasseraufbereitung mit Ultraschall; Projekt-Abschnitt 1990 (1990) Frischherz H., Benes E., Stuckhart W., Ilmer A., Gröschl M., Bolek W. 18

95 Anaerobe Abwasserreinigung - Ein Modell zur Berechnung und Darstellung der maßgebenden chemischen Parameter (1991) Svardal K. 22

Anhang VII Band Nr Preis €

96 EDV-Einsatz auf Abwasserreinigungsanlagen (1991) ÖWWV-Fortbildungskurs 1991, TU-Wien 29

97 Entfernung von Phosphorverbindungen bei der Abwasserreinigung (1991) ÖWWV-Fortbildungskurs 1991, TU-Wien 25

98 Auswirkungen der Wasserrechtsgesetznovelle 1990 auf Behörden, Planer und Betreiber kommunaler Abwasserreinigungsanlagen - aus technischer, rechtlicher und wirtschaftlicher Sicht (1991) 26. ÖWWV-Seminar, Ottenstein 1991 36

99 Geruchsemissionen aus Abwasserreinigungsanlagen (1991) ÖWWV-Fortbildungskurs 1991, 22

100 Anpassung von Kläranlagen an den Stand der Technik (1992) ÖWWV-Fortbildungskurs 1992, TU-Wien vergriffen

101 Umweltbezogene Planung wasserbaulicher Maßnahmen an Fließgewässern (1992) Pelikan B. 18

102 Erfassung hydrometeorologischer Elemente in Österreich im Hinblick auf den Wasserhaushalt (1992) Behr O. i.V.

103 Wasser- und Abfallwirtschaft in dünn besiedelten Gebieten (1992) 27. ÖWWV-Seminar Ottenstein 1992 36

104 Virus Contamination of the Environment (1992) Methods and Control vergriffen

105 Fließgewässer und ihre Ökologie (1993) ÖWAV-Fortbildungskurs 1992, TU-Wien 22

106 Festlegung einer Dotierwassermenge über Dotationsversuche (1992) Mader H. 22

107 Wasserrechtsgesetznovelle 1990 und neue Emissionsverordnungen (1992) Vorträge anläßlich der UTEC 1992 29

108 Chemische Analytik für einen zeitgemäßen Gewässerschutz (1992) Vorträge anläßlich der UTEC 1992 29

109 Kulturtechnik und Wasserwirtschaft heute (1994) Teil 10 - Beiträge zum Seminar an der Universität für Bodenkultur im November 1994 i.V.

Anhang VIII Band Nr Preis €

110 Bemessung u. Betrieb von Kläranlagen zur Stickstoffentfernung (1993) ÖWAV-Seminar 1993, TU-Wien 36

111 Wasserreserven in Österreich - Schutz und Nutzung in Gegenwart und Zukunft (1993) 28. ÖWAV-Seminar Ottenstein 1993 vergriffen

112 Contamination of the Environment by Viruses and Methods of Control (1993) 18

113 Wasserkraft () O.Univ.-Prof. Dipl.-Ing. Dr.techn. S. Radler anläßlich seiner Emeritierung vergriffen

114 Klärwärter-Grundkurs (1994) 2. Auflage 1994 vergriffen

115 Beitrag zur Reduzierung der Abwasseremissionen der Bleicherei beim Sulfatverfahren (1994) Urban W. ISBN 3-85234-001-2 22

116 Eigenüberwachung von Abwasserreinigungsanlagen für den Gewässerschutz (1994) ÖWAV-Seminar 1994, TU-Wien ISBN 3-85234-002-0 25

117 Abwasserreinigungskonzepte - Internationaler Erfahrungsaustausch über neue Entwicklungen (1995) ÖWAV-Seminar 1994, TU Wien ISBN 3-85234-003-9 25

118 3 Jahre WRG-Novelle (1994) 29. ÖWAV-Seminar: Ottenstein 1994 ISBN 3-85234-004-7 19

119 Landeskulturelle Wasserwirtschaft (1994) anläßlich der Emeritierung von o.Univ.-Prof. Dipl.-Ing. Dr. H. Supersperg vergriffen

120 Gewässerbetreuungskonzepte - Stand und Perspektiven (1994) Beiträge zur Tagung an der BOKU 1994 ISBN 3-85234-010-1 32

121 Generelle Entwässerungsplanung im Siedlungsraum (1996) ÖWAV-Seminar 1995, TU Wien ISBN 3-85234-011-X 29

Anhang IX Band Nr Preis €

122 Bedeutung von geowissenschaftlicher Zusatzinformation für die Schätzung der Transmissivitätsverteilung in einem Aquifer (1994) Kupfersberger H. 18

123 Modellierung und Regionalisierung der Grundwassermengenbildung und des Bodenwasserhaushaltes (1994) Holzmann, H. 22

124 Pflanzenkläranlagen - Stand der Technik, Zukunftsaspekte (1995) ÖWAV-Seminar, BOKU Wien ISBN 3-85234-014-4 22

125 Abwasserreinigung - Probleme bei der praktischen Umsetzung des Wasserrechtsgesetzes, (1995) ÖWAV-Seminar 1995, TU-Wien ISBN 3-85234-015-2 32

126 Konfliktfeld Landwirtschaft - Wasserwirtschaft (1995) 30. ÖWAV-Seminar, Ottenstein 1995 ISBN 3-85234-016-0 29

127 Alte und neue Summenparameter (1995) ÖWAV-Seminar 1995, TU-Wien ISBN 3-85234-017-9 29

128 Viruskontamination der Umwelt und Verfahren der Kontrolle (deutsch oder englisch) (1995) 4. Symposium Univ.Prof.Dr. R. Walter ISBN 3-85234-019-5 0

129 Einfluß von Indirekteinleitungen auf Planung und Betrieb von Abwasseranlagen (1996) ÖWAV-Seminar 1996, TU-Wien ISBN 3-85234-020-9 vergriffen

130 Zentrale und dezentrale Abwasserreinigung (1996) 31. ÖWAV-Seminar, Ottenstein 1996 ISBN 3-85234-021-7 36

131 Methoden der Planung und Berechnung des Kanalisationssystems (1996) ÖWAV-Seminar 1996, BOKU-Wien ISBN 3-85234-022-5 29

Anhang X Band Nr Preis €

132 Scale and Scaling in Hydrology (1996) Blöschl G. ISBN 3-85234-023-3 vergriffen

133 Kulturtechnik und Wasserwirtschaft heute (11) (1996) Integrale Interpretation eines zeitgemäßen Gewässerschutzes ISBN 3-85234-024-0 12

134 Ein Beitrag zur Charakterisierung von Belüftungssystemen für die biologische Abwasserreinigung nach dem Belebungsverfahren mit Sauerstoffzufuhrmessungen (1996) Frey W. ISBN 3-85234-025-X 22

135 Nitrifikation im Belebungsverfahren bei maßgebendem Industrieabwassereinfluß (1996) Nowak O. ISBN 3-85234-026-8 36

136 1. Wassertechnisches Seminar (1996) Nebenprodukte von Desinfektion und Oxidation bei der Trinkwasseraufbereitung ISBN 3-85234-027-6 i.V.

137 Modellanwendung bei Planung und Betrieb von Belebungsanlagen (1997) ÖWAV - Seminar 1997, TU-Wien ISBN 3-85234-028-4 32

138 Nitrifikationshemmung bei kommunaler Abwasserreinigung (1997) Schweighofer P. ISBN 3-85234-029-2 25

139 Ein Beitrag zu Verständnis und Anwendung aerober Selektoren für die Blähschlammvermeidung (1997) Prendl L. ISBN 3-85234-030-6 22

140 Auswirkungen eines Kläranlagenablaufes auf abflußschwache Vorfluter am Beispiel der Kläranlage Mödling und des Krottenbaches (1997) Franz A. ISBN 3-85234-031-4 25

141 Neue Entwicklungen in der Abwassertechnik (1997) ÖWAV - Seminar 1997, TU-Wien ISBN 3-85234-032-2 36

Anhang XI Band Nr Preis €

142 Kulturtechnik und Wasserwirtschaft heute (11) (1997) Abfallwirtschaft und Altlastensanierung morgen ISBN 3-85234-033-0 18

143 Abwasserbeseitigung und Wasserversorgung in Wien (1997) Eine ökonomische Beurteilung der Einnahmen, Ausgaben und Kosten Kosz M. ISBN 3-85234-034-9 22

144 Raum-Zeitliche Variabilitäten im Geschiebehaushalt und dessen Beeinflussung am Beispiel der Drau (1997) Habersack H. ISBN 3-85234-035-7 29

145 Fortbildungskurs: Biologische Abwasserreinigung (1998) ÖWAV - Seminar 1998, TU-Wien ISBN 3-85234-036-5 vergriffen

146 2. Wassertechnisches Seminar (1998) Desinfektion in der Trinkwasseraufbereitung ISBN 3-85234-037-3 i.V.

147 Eigenüberwachung und Fremdüberwachung bei Kläranlagen (1998) 32. ÖWAV-Seminar , Linz 1998 ISBN 3-85234-038-1 36

148 Grundwasserdynamik (1998) ISBN 3-85234-039-C 36

149 Die Tradition in der Kulturtechnik (1998) Kastanek F. Simulationsanwendung bei der Störung durch poröses Medium (1998) Loiskandl W. ISBN 3-85234-040-4 22

150 Auswirkungen von Niederschlagsereignissen und der Schneeschmelze auf Karstquellen (1998) Steinkellner M. ISBN 3-85234-041-1 36

151 Experiences with soil erotion models (1998) ISBN 3-85234-042-X 29

Anhang XII Band Nr Preis €

152 Ein Beitrag zur Optimierung der Stickstoffentfernung in zweistufigen Belebungsanlagen (1998) Dornhofer K. ISBN 3-85234-043-8 25

153 Hormonell aktive Substanzen in der Umwelt (1998) ÖWAV / UBA Seminar 1998, BOKU Wien ISBN 3-58234-044-6 vergriffen

154 Erfassung, Bewertung und Sanierung von Kanalisationen (1998) ÖWAV Seminar 1999, BOKU Wien ISBN 3-8523-045-4 29

155 Nährstoffbewirtschaftung und Wassergüte im Donauraum (1999) ÖWAV - Seminar 1999, TU-Wien ISBN 3-85234-046-2 32

156 Der spektrale Absorptionskoeffizient zur Bestimmung der organischen Abwasserbelastung (1999) UV-Seminar 1998, Duisburg ISBN 3-85234-047-0 22

157 Bedeutung und Steuerung von Nährstoff- und Schwermetallflüssen des Abwassers (1999) Zessner M. ISBN 3-85234-048-9 25

158 Entwicklung einer Methode zur Bewertung von Stoffbilanzen in der Abfallwirtschaft (1999) Rechberger H. ISBN 3-85234-049-7 vergriffen

159 Sicherheit und Gesundheitsschutz auf Abwasseranlagen und deren Evaluierung (2000) ÖWAV – Seminar 2000, TU-Wien ISBN 3-85234-050-0 22

160 Auswirkungen von Klimaänderungen auf die Hydrologie alpiner Einzugsgebiete (2000) Hebenstreit K. ISBN 3-85234-051-9 25

Anhang XIII Band Nr Preis €

161 Innovative Messtechnik in der Wasserwirtschaft (2000) Präsentation eines Forschungsprojektes ÖWAV – Seminar 2000, BOKU – Wien ISBN 3-85234-052-7 vergriffen

162 Sickerwasser und Oberflächenabdichtung auf Reaktordeponien (2000) ÖWAV - Seminar 2000, Wirtschaftskammer Wien ISBN 3-85234-053-5 25

163 Abfall- und Abwasserentsorgung in kleinen Verhältnissen (2000) ÖWAV - Seminar 2000, Ottenstein ISBN 3-85234-054-3 25

164 Niederschlag-Abfluss-Modellierung – Simulation und Prognose (2000) ÖWAV-Seminar 2000, TU Wien ISBN 3-85234-055-1 i.V. 165 Mehrdimensionale Abflussmodellierung am Beispiel der Lafnitz (2000) Habersack, H. / Mayr, P. / Girlinger, R. / Schneglberger, St. ISBN 3-85234-056-x 25 166 Anpassung von Kläranlagen – Planung und Betrieb (2001) ÖWAV-Seminar 2001, TU Wien ISBN 3-85234-057-8 40 167 Bepflanzte Bodenfilter zur weitergehenden Reinigung von Oberflächenwasser und Kläranlagenabläufen (2001) Laber J. ISBN 3-85234-058-6 25 168 Kanalbetrieb und Niederschlagsbehandlung (2001) ÖWAV-Seminar 2001, BOKU Wien. ISBN 3-85234-059-4 29 169 Development of a Simulation Tool for Subsurface Flow Constructed Wetlands (Entwicklung eines Simulationsmodells für bepflanzte Bodenfilter) (2001) Langergraber G. ISBN 3-85234-060-8 25

170 Simulation von Niederschlagszeitreihen mittels stochastischer Prozess-modelle unter Berücksichtigung der Skaleninvarianz (2001) Bogner ISBN 3-85234-061-6 i.V.

171 Sewage Sludge Disposal – Sustainable and/or Reliable Solutions (2001) ÖWAV / EWA Workshop 2001, TU-Wien ISBN 3-85234-062-4 25

Anhang XIV Band Nr Preis €

172 Stickstoffentfernung mit Biofiltern (2002) Nikolavcic B. ISBN 3-85234-063-2 i.V.

173 Anaerobe Abwasserreinigung: Beeinflussende Faktoren der Versäuerung eines Zitronesäurefabrikabwassers (2002) Moser D. ISBN 3-85234-064-0 i.V.

174 Gewässerschutz bei Entlastungsbauwerken der Mischkanalisation (2002) Fenz R. ISBN 3-85234-065-9 i.V.

175 Wechselwirkung von physikalischen, chemischen und biotischen Prozessen in aquatischen Systemen (2002) Kreuzinger N. ISBN 3-85234-066-7 i.V.

176 Benchmarking in der Abwasserentsorgung (2002) ÖWAV Workshop Februar 2002, TU-Wien ISBN 3-85234-067-5 30

177 Klärschlamm (2002) Möglichkeiten und Verfahren zur Verwertung / Entsorgung ab 2004 ÖWAV Seminar April 2002, Wirtschaftskammer Österreich Schlammbehandlung und Entsorgung ÖWAV / TU – Workshop September 2000, TU-Wien ISBN 3-85234-068-3 30

Anhang XV Die Bände sind zu beziehen bei: Institut für Wassergüte und Abfallwirtschaft der Technischen Universität Wien Karlsplatz 13/226, A-1040 Wien

Band: 12, 15, 16, 20, 28, 34, 35, 36, 37, 47, 49, 53, 54, 56, 57, 58, 61, 62, 63, 64, 65, 69, 73, 81, 82, 84, 95, 96, 97, 98, 99, 100, 105, 107, 108, 110, 114, 116, 117, 121, 125, 127, 129, 130, 134, 135, 137, 138, 139, 140, 141, 143, 145, 147, 152, 153, 155, 156, 157, 158, 159, 161, 162, 166, 171, 172, 173, 174, 175, 176, 177

Institut für Hydraulik, Gewässerkunde und Wasserwirtschaft der Technischen Universität Wien Karlsplatz 13, A-1040 Wien

Band: 1, 2, 8, 9, 17, 21, 23, 26, 30, 31, 41, 42, 52, 66, 68, 74, 90, 91, 92, 102, 122, 132, 148, 164

Institut für Wasserwirtschaft, Hydrologie und konstruktiven Wasserbau der Universität für Bodenkultur, Muthgasse 18, A-1190 Wien

Band: 18, 19, 32, 38, 43, 44, 45, 48, 50, 55, 59, 60, 70, 75, 78, 86, 89, 93, 101, 106, 109, 113, 123, 144, 160, 165, 167, 169

Institut für Wasservorsorge, Gewässerökologie und Abfallwirtschaft der Universität für Bodenkultur, Muthgasse 18, A-1190 Wien

Band: 22, 29, 39, 40, 46, 67, 71, 72, 76, 77, 80, 83, 85, 87, 88, 94, 103, 112, 115, 118, 120, 124, 126, 128, 131, 133, 136, 142, 146, 150, 154, 163, 167, 168, 169

Institut für Hydraulik und landeskulturelle Wasserwirtschaft der Universität für Bodenkultur Muthgasse 18, A-1190 Wien

Band: 119, 149, 151, 170

Anhang XVI