Ammonia Sanitisation of Human Excreta Treatment Technology for Production of Fertiliser Annika Nordin Faculty of Natural Resources and Agricultural Sciences Department of Energy and Technology and National Veterinary Institute Uppsala Doctoral Thesis Swedish University of Agricultural Sciences Uppsala 2010 Acta Universitatis agriculturae Sueciae 2010:67 Cover photo and montage: Annika Nordin ISSN 1652-6880 ISBN 978-91-576-7512-5 © 2010 Annika Nordin, Uppsala Print: SLU Service, Uppsala 2010 Ammonia Sanitisation of Human Excreta. Treatment Technology for Production of Fertiliser Abstract Safe reuse of plant nutrients from human excreta increases the sustainability of society and promotes health, both by decreasing disease transmission and by increasing agricultural production. This thesis examined ammonia sanitisation as a treatment method to produce a hygienically safe fertiliser from source-separated urine and faeces. Salmonella spp. and E. coli O157:H7 were inactivated to a high degree even at low NH3 concentrations and temperatures. It was possible to model Salmonella spp. inactivation using these two parameters. Salmonella spp. inactivation is suggested to be verified by determining inactivation of faecal coliforms. Between NH3 concentrations 20 and 60 mM, a sharp decrease in inactivation was observed at 24 ºC or below for Enterococcus spp., bacteriophages and Ascaris eggs, with insignificant inactivation of the latter during 6 months. Urine contains sufficiently high total ammonia concentration and pH for self- sanitisation. Keeping the urine as concentrated as possible proved critical in achieving NH3 concentrations that inactivated Ascaris eggs. Sun exposure increased urine temperature and NH3 and shortened treatment time, and is feasible when urine containers are small. Urea treatment of faeces increased pH and total ammonia concentrations, both contributing to formation of NH3. The final value and stability of the pH achieved depended on initial pH and other material properties, but increased with increasing urea addition. At high pH caused by ash addition, urea was not degraded. When urea was added alone, it could not be confirmed that it was fully degraded. Organism inactivation was always faster in urea-treated faeces compared with untreated faeces. Urea treatment substantially shortened treatment time compared with storage, especially at the higher temperatures studied (24 and 34 ºC). Sanitation systems that collect urine and faeces separate and sanitise them by ammonia permit a high degree of hygienically safe plant nutrient reuse. Keywords: Ammonia, Ascaris, faeces, fertiliser, inactivation model, pathogen, Salmonella, sanitisation technology, sustainable sanitation, urine Author’s address: Annika Nordin, SLU, Department of Energy and Technology, P.O. Box 7032, SE 750 07 Uppsala, Sweden E-mail: [email protected] Dedication Till Paloma och till minnet av mormor Elsa As our circle of knowledge expands, so does the circumference of darkness surrounding it. Albert Einstein Contents List of Publications 9 Abbreviations 12 Terms 13 1 Introduction 15 2 Objectives 17 3 Background 19 3.1 Human excreta as fertiliser 19 3.1.1 Closing the nutrient loop 19 3.1.2 Constraints with excreta-derived fertilisers 21 3.2 Pathogens in human excreta 22 3.3 Excreta treatment technologies 24 3.3.1 Disease transmission and prevention 24 3.3.2 Sanitation systems and excreta fractions 25 3.3.3 Faecal treatments 26 3.4 Evaluation of treatment efficiency 29 3.4.1 Model and indicator organisms 29 3.4.2 Process and product verification 31 3.5 Chemical disinfection with ammonia 33 3.5.1 Urea as a source of ammonia 33 3.5.2 Ammonia-ammonium equilibrium 33 3.5.3 Mechanisms of inactivation 35 4 Materials and Methods 37 4.1 Pathogens and indicator and model organisms 37 4.2 Treatment at constant temperatures 37 4.3 Urine treatment at varying temperatures 38 4.4 Microbial reduction kinetics 39 5 Results: Summary of Papers I-IV 41 5.1 Urine treatment 41 5.1.1 Ammonia and pH in urine 41 5.1.2 Temperatures at ambient exposure 42 5.1.3 NH3 formation in urine 43 5.1.4 Microbial inactivation 43 5.2 Urea treatment of faeces 46 5.2.1 Ammonia and pH in faecal treatments 46 5.2.2 NH3 formation in faecal treatments 48 5.2.3 Microbial inactivation 49 6 Results: Inactivation Models 51 6.1 NH3 and temperature-dependent Salmonella inactivation 51 6.1.1 Model aim and assumptions 51 6.1.2 Inactivation model 52 6.2 Inactivation of related organisms 55 6.2.1 Salmonella and E. coli O157:H7 55 6.2.2 Salmonella and Enterococcus 56 6.3 Shouldered inactivation of Ascaris eggs 57 7 Discussion 61 7.1 Organism inactivation 61 7.1.1 Salmonella 61 7.1.2 Enterococcus 64 7.1.3 Ascaris eggs 65 7.1.4 Bacteriophages 68 7.2 Achieving critical NH3 concentrations 70 7.2.1 pH 70 7.2.2 Ammonia nitrogen 71 7.2.3 Temperature 73 7.3 Ammonia sanitisation efficiency 74 7.3.1 Product and process verification 74 7.3.2 WHO guidelines and Ammonia sanitisation 76 7.4 Treatment implications 76 7.4.1 Source-separated urine 76 7.4.2 Faecal urea treatment 80 7.4.3 Sanitising other biomaterial 83 8 Systems for Excreta Reuse 85 8.1 Sanitation systems and excreta handling 86 8.1.1 Collection and primary treatment 86 8.1.2 Secondary treatment for fertiliser production 87 8.2 Excreta fertilisers 89 8.2.1 Nutrient content 89 8.2.2 Application 89 8.2.3 Fertiliser management 90 8.3 Sustainable sanitation and health 91 9 Conclusions 93 10 Future research 95 References 97 Acknowledgements 109 List of Publications This thesis is based on the work contained in the following papers, referred to by Roman numerals in the text: I Björn Vinnerås, Annika Nordin, Charles Niwagaba and Karin Nyberg (2008). Inactivation of bacteria and viruses in human urine depending on temperature and dilution rate. Water Research 42 (2008), 4067-4074. II Annika Nordin, Karin Nyberg and Björn Vinnerås (2009). Inactivation of Ascaris eggs in source-separated urine and faeces by ammonia at ambient temperatures. Applied and Environmental Microbiology 75(3), 662- 667. III Annika Nordin, Charles Niwagaba, Håkan Jönsson and Björn Vinnerås (2009). Pathogen and indicator inactivation in source-separated human urine heated by sun. Submitted Manuscript. IV Annika Nordin, Jakob R. Ottoson and Björn Vinnerås (2009). Sanitation of faeces from source-separating dry toilets using urea. Journal of Applied Microbiology 107(2009), 1579-1587. Papers I-IV are reproduced with the permission of the publishers. 9 The contribution of Annika Nordin to the papers included in this thesis was as follows: I Nordin and Vinnerås planned the study and Nordin, Niwagaba, Nyberg and Vinnerås performed it. Vinnerås and Nordin did the writing with revision by co-authors. II Nordin and Vinnerås planned the study and Nordin and Nyberg performed it. Nordin and Vinnerås did the writing with revision by Nyberg. III Niwagaba, Nordin, Jönsson and Vinnerås planned the study. Nordin and Niwagaba performed the study and did the writing with revisions by Jönsson and Vinnerås. IV Nordin and Vinnerås planned the study and Nordin performed it. Nordin and Vinnerås did the writing with revision by Ottoson. Papers I-IV are reproduced with the permission of the publishers. 10 Other papers produced but not included in the thesis: V Jacob Ottoson, Annika Nordin, Dietrich von Rosen and Björn Vinnerås (2008). Salmonella reduction in manure by the addition of urea and ammonia. Bioresource Technology 99(6) 1610-1615. VI Björn Vinnerås, Michael Hedenquist, Annika Nordin and Anders Wilhelmson (2009). Peepoo bag: self-sanitising biodegradable toilet. Water Science and Technology 59(9) 1743-1749. VII Björn Vinnerås, Caroline Schönning and Annika Nordin (2006). Identification of the microbial community in biogas systems and evaluation of microbial risks from gas usage. Science of the Total Environment 367(2006), 606-615. 11 Abbreviations Cfu Colony-forming unit dsDNA Double-stranded deoxyribonucleic acid EC The European Commission E. coli Escherichia coli E. faecalis Enterococcus faecalis Ent. Coli Entamoeba coli Pfu Plaque-forming unit S. Typhimurium Salmonella enterica subspecies 1 serovar Typhimurium SEPA The Swedish Environmental Protection Agency spp. Sub-species ssDNA Single-stranded deoxyribonucleic acid ssRNA Single-stranded ribonucleic acid TAN Total ammonia nitrogen TN Total nitrogen TS Total solids TTC Total thermotolerant coliforms UNICEF The United Nations Children’s Fund USEPA U S Environmental Protection Agency WHO World Health Organization 12 Terms Censored The true value is below a value x (left censoring), but it is value unknown by how much. Given as <x NH3 In this thesis a short term for NH3 (aq), i.e. the concentration of un-ionised ammonia solved in liquid phase. Pathogen Disease-causing microorganism Sanitation Formulation and application of measures to protect human health from risks, microbiological, biological or chemical, related to hazardous waste Sanitisation Disinfection, i.e. inactivation of microorganisms, not necessarily all, but to a level considered sufficient to protect human and animal health t90, t99 etc. Time for decimal reduction, i.e. 1, 2 log10 reduction etc. derived from first order decay Zoonose Microorganism capable of infecting humans and animals 13 14 1 Introduction Sanitation of toilet waste has been hailed by the British Medical Journal as the greatest health breakthrough since 1840, greater than the discoveries of antibiotics, anaesthesia, vaccines and DNA. However, inadequate sanitation is still a major problem in low income countries and infectious diarrhoea accounts for more deaths than AIDS, malaria and measles combined (UNICEF/WHO, 2009). For example, nearly 80% of the 300 000 conflict- related deaths in Darfur were due to diseases associated with diarrhoea, not to violence (Degomme & Guha-Sapir, 2010), indicating that the impact from unsanitary conditions is even greater when healthcare infrastructure is lacking. The number of people lacking ‘improved’ sanitation in 2004 was estimated to be 2.6 billion, i.e.