Nitrogen based sanitation of source separated faecal matter
To fulfil the UN millennium goals for sustainable development, there is an urgent need for alternatives to conventional water based sanitation. Faeces and urine contain valuable plant nutrients and should be considered as resources rather than wastes. Collection with efficient water usage enables fa...
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| Formato: | Otro |
| Lenguaje: | sueco Inglés |
| Publicado: |
2006
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| Materias: | |
| Acceso en línea: | https://stud.epsilon.slu.se/12404/ |
| _version_ | 1855572057080725504 |
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| author | Nordin, Annika |
| author_browse | Nordin, Annika |
| author_facet | Nordin, Annika |
| author_sort | Nordin, Annika |
| collection | Epsilon Archive for Student Projects |
| description | To fulfil the UN millennium goals for sustainable development, there is an urgent need for alternatives to conventional water based sanitation. Faeces and urine contain valuable plant nutrients and should be considered as resources rather than wastes. Collection with efficient water usage enables faeces and urine to be reused and environmental pollution may be better prevented. When using human excreta as plant fertilisers, it is important to prevent disease transmission by reducing the content of gastrointestinal pathogens. Nitrogen based treatment of faeces and manure with ammonium hydroxide and urea has been shown to be an efficient method for inactivating bacterial pathogens, nematode eggs and protozoan cysts. The substance responsible for microbial inactivation is uncharged ammonia, NH3 (aq). As ammonia is a weak base, the ammonia equilibrium can be controlled by additions of alkaline agents such as lime. A pH above 8 is needed to produce substantial amounts of ammonia in the form of NH3.
The objective of this study was to examine the potential of nitrogen based treatment for reduction of human bacterial and parasitic pathogens in faeces collected separately from a dry sanitation system. The faeces samples were inoculated with Enterococcus faecalis, Salmonella Typhimurium, Escherichia coli O157:H7 and Ascaris suum eggs prior to treatment. Treatments were performed at 14°C and consisted of ammonia (1% w/w), urea (0.5, 1 and 2% w/w) and/or slaked lime and storage. Inactivation of bacteria was monitored by plate count methods and viability of ascaris eggs by microscopy. Ammonia content was determined by distillation and titration and NH3 concentration calculations based on pH.
Addition of ammonia, urea and/or lime resulted in an increase in pH from the initial 7.14, whereas the pH in the storage treatment decreased. The 1% ammonia treatment with equimolar addition of total ammonia as 2% urea resulted in a higher pH (10.2) than 2% urea (9.2). Addition of urea gave a more stable pH over time compared to addition of lime, although pH declined with time in all treatments, thus affecting NH3 concentration. On day 21, 1% ammonia and 2% urea were the only treatments with sufficiently high pH to produce a substantial amount of NH3, although reductions in bacteria fitted well to an exponential function even after day 21. No viable A. suum eggs were observed after 41 days in the 0.5% urea, 2% urea and storage treatments. On day 12, no significant differences in viability could be observed between the different treatments. However a tendency for reduced A. suum viability according to the urea gradient could be observed. E. faecalis was less sensitive to the treatments than any of the pathogenic bacteria studied and E. coli was more sensitive than S. Typhimurium, although the differences were small. The 1% ammonia and 2% urea treatments were the most efficient at reducing bacteria, resulting in a decimal reduction time of 0.13-5 days for 1% ammonia treatment and 0.2-41 days for 2% urea treatment. Regression analysis of the coefficients k for the bacterial reduction function and the concentrations of NH3 in the treatments revealed a significant linear correlation for all bacteria studied. However, pH was only significantly correlated to k for E. faecalis, though weaker than to NH3. The relationship between NH3 concentration and reduction coefficient gave a change in k of 0.022 units per mM NH3 for E. coli and 0.014 units for S. Typhimurium. The pathogenic bacteria were more sensitive to NH3 concentration than E. faecalis, with a change in k of 0.00054 units per mM NH3. As E. faecalis seemed to have a higher threshold concentration for inactivation by ammonia based treatments and its reduction time exceeded that of the pathogenic bacteria studied, E. faecalis might not be a suitable indicator organism for this method.
In conclusion, treatment with 1% ammonia, 2% urea or 1% urea with lime addition was sufficient to give a 6 log10 reduction of the pathogenic bacteria studied, within 3 weeks of treatment. A. suum had a rapid inactivation but seemed to be affected by other environmental parameters in addition to ammonia concentration. |
| format | Otro |
| id | RepoSLU12404 |
| institution | Swedish University of Agricultural Sciences |
| language | Swedish Inglés |
| publishDate | 2006 |
| publishDateSort | 2006 |
| record_format | eprints |
| spelling | RepoSLU124042017-10-30T12:52:19Z https://stud.epsilon.slu.se/12404/ Nitrogen based sanitation of source separated faecal matter Nordin, Annika Dept. of Microbiology Human medicine, health, and safety To fulfil the UN millennium goals for sustainable development, there is an urgent need for alternatives to conventional water based sanitation. Faeces and urine contain valuable plant nutrients and should be considered as resources rather than wastes. Collection with efficient water usage enables faeces and urine to be reused and environmental pollution may be better prevented. When using human excreta as plant fertilisers, it is important to prevent disease transmission by reducing the content of gastrointestinal pathogens. Nitrogen based treatment of faeces and manure with ammonium hydroxide and urea has been shown to be an efficient method for inactivating bacterial pathogens, nematode eggs and protozoan cysts. The substance responsible for microbial inactivation is uncharged ammonia, NH3 (aq). As ammonia is a weak base, the ammonia equilibrium can be controlled by additions of alkaline agents such as lime. A pH above 8 is needed to produce substantial amounts of ammonia in the form of NH3. The objective of this study was to examine the potential of nitrogen based treatment for reduction of human bacterial and parasitic pathogens in faeces collected separately from a dry sanitation system. The faeces samples were inoculated with Enterococcus faecalis, Salmonella Typhimurium, Escherichia coli O157:H7 and Ascaris suum eggs prior to treatment. Treatments were performed at 14°C and consisted of ammonia (1% w/w), urea (0.5, 1 and 2% w/w) and/or slaked lime and storage. Inactivation of bacteria was monitored by plate count methods and viability of ascaris eggs by microscopy. Ammonia content was determined by distillation and titration and NH3 concentration calculations based on pH. Addition of ammonia, urea and/or lime resulted in an increase in pH from the initial 7.14, whereas the pH in the storage treatment decreased. The 1% ammonia treatment with equimolar addition of total ammonia as 2% urea resulted in a higher pH (10.2) than 2% urea (9.2). Addition of urea gave a more stable pH over time compared to addition of lime, although pH declined with time in all treatments, thus affecting NH3 concentration. On day 21, 1% ammonia and 2% urea were the only treatments with sufficiently high pH to produce a substantial amount of NH3, although reductions in bacteria fitted well to an exponential function even after day 21. No viable A. suum eggs were observed after 41 days in the 0.5% urea, 2% urea and storage treatments. On day 12, no significant differences in viability could be observed between the different treatments. However a tendency for reduced A. suum viability according to the urea gradient could be observed. E. faecalis was less sensitive to the treatments than any of the pathogenic bacteria studied and E. coli was more sensitive than S. Typhimurium, although the differences were small. The 1% ammonia and 2% urea treatments were the most efficient at reducing bacteria, resulting in a decimal reduction time of 0.13-5 days for 1% ammonia treatment and 0.2-41 days for 2% urea treatment. Regression analysis of the coefficients k for the bacterial reduction function and the concentrations of NH3 in the treatments revealed a significant linear correlation for all bacteria studied. However, pH was only significantly correlated to k for E. faecalis, though weaker than to NH3. The relationship between NH3 concentration and reduction coefficient gave a change in k of 0.022 units per mM NH3 for E. coli and 0.014 units for S. Typhimurium. The pathogenic bacteria were more sensitive to NH3 concentration than E. faecalis, with a change in k of 0.00054 units per mM NH3. As E. faecalis seemed to have a higher threshold concentration for inactivation by ammonia based treatments and its reduction time exceeded that of the pathogenic bacteria studied, E. faecalis might not be a suitable indicator organism for this method. In conclusion, treatment with 1% ammonia, 2% urea or 1% urea with lime addition was sufficient to give a 6 log10 reduction of the pathogenic bacteria studied, within 3 weeks of treatment. A. suum had a rapid inactivation but seemed to be affected by other environmental parameters in addition to ammonia concentration. För att uppnå de av FN uppsatta milleniummålen, att halvera det antal människor som saknar fullgod sanitet, måste alternativ till vattenburen sanitet utvecklas och implementeras. Fekalier och urin måste därvid ses som en resurs och en väg att sluta näringskretsloppet och därmed minimera miljöpåverkan. För att säkerställa mänsklig hälsa när fekalier och urin används för jordbruksproduktion krävs behandling som förhindrar spridning av sjukdomsalstrande mikroorganismer. Kvävebaserade behandlingar med ammoniumhydroxid och urea och har visat sig effektiva att reducera bakteriella patogener, nematodägg och protozoer i fekalier och gödsel. Det är oladdad ammoniak, NH3, som påverkar mikrobiell inaktivering. Då ammoniak är en svag bas påverkas jämvikten mellan oladdad och laddad ammoniak av pH. Därmed kan andelen ammoniak som förekommer som NH3 styras med tillsatser av alkaliska substanser, såsom kalk. Ett pH över 8 är nödvändigt för att uppnå betydande koncentration av NH3. Syftet med denna studie var att undersöka potentialen hos kvävebaserade behandlingar för reduktion av bakteriella och parasitiska patogener i källsorterade fekalier. Fekalier från ett torrsorterande system behandlades vid 14°C med ammoniak (1%), urea (0,5, 1 och 2%) och/eller kalk och lagring. Enterococcus faecalis, Salmonella Typhimurium, Escherichia coli O157:H7 and Ascaris suum ägg tillsattes före behandling. Den bakteriella reduktionen studerades med plattmetoder och överlevnaden hos ascaris ägg observerades i mikroskop. Innehållet av ammoniak destillerades och titrerades för koncentrationsbestämmning och andelen NH3 beräknades utifrån pH. Alla behandlingar förutom lagring resulterade i en ökning av pH från det initiala 7,14. Behandling med 1% ammoniak med samma molara tillsats av total ammoniak som behandling med 2% urea gav ett högre pH jämfört med 2% urea, 10,2 respektive 9,2. Behandling med urea gav ett pH som var stabilare över tid jämfört med pH från behandlingar med kalk. I alla behandlingarna minskade pH över tid vilket således påverkade koncentrationen av NH3. Dag 21 var det bara behandlingarna med 1% ammoniak och 2% urea som höll ett tillräckligt högt pH för att ge någon betydande andel NH3. Dock följde den bakteriella reduktionen en exponentiell avdödning även i de behandlingar som efter dag 21 höll låg NH3(aq) koncentration. Inga levande A. suum ägg kunde observeras efter 41 dagar i de studerade behandlingarna: urea 0,5% och 2% och lagring. Dag 12 kunde man se en trend med lägre överlevnad med ökad ureatillsats, dock inte statistiskt signifikant. Av de studerade bakterierna visade sig E. faecalis minst känslig för de olika behandlingarna. E. coli var generellt känsligare för behandlingarna än S. Typhimurium, dock var resultaten för dessa två patogena bakterier mer lika vad gäller känslighet och reduktionstid jämfört med E. faecalis. Behandling med 1% ammoniak eller 2% urea visade sig vara mest effektiv för bakteriell avdödning med decimalreduktionstid 0,13-5 dagar för 1% ammoniak och 0,2-41 dagar för 2% urea. Regressionsanalys av reduktionskoefficienter k mot koncentrationen NH3 visade ett linjärt samband för alla studerade bakterier. Bara E. faecalis gav ett signifikant samband mellan k och pH, dock svagare än för NH3. Det linjära sambandet gav en förändring av k med 0,022 enheter per mM NH3 för E. coli och 0,014 for S. Typhimurium. E. faecalis som var mindre känslig för behandlingarna hade en förändring av koefficienten med 0,00054 enheter per mM NH3. E. faecalis visade sig mycket mer tålig än de patogena bakterierna som studerades och en högre tröskelkoncentration av oladdad ammoniak verkar krävas för effektiv reduktion. Eftersom reduktionstiden för E. faecalis i vissa fall överskred reduktionstiden för de patogena bakterierna mångfalt verkar inte E. faecalis vara ett passande val av indikatororganism för reduktion av bakteriella patogener med denna metod. Slutsatsen är att behandling med 1% ammoniak, 2% urea eller 1% urea med kalktillsats verkar vara goda behandlingsalternativ för källsorterade fekalier då dessa behandlingar gav en 6 log10 reduktion av de patogena bakterierna inom tre veckor. A.suum verkar även ha påverkats av andra faktorer än NH3 koncentration då även lagring gav en snabb reduktion av överlevnaden. 2006-09-01 Other NonPeerReviewed application/pdf sv https://stud.epsilon.slu.se/12404/1/nordin_a_171030.pdf Nordin, Annika, 2006. Nitrogen based sanitation of source separated faecal matter. UNSPECIFIED, Uppsala. Uppsala: (NL, NJ) > Dept. of Microbiology <https://stud.epsilon.slu.se/view/divisions/4024.html> (NL, NJ) > Dept. of Biometry and Engineering <https://stud.epsilon.slu.se/view/divisions/HIST=3A120069.html> urn:nbn:se:slu:epsilon-s-8424 eng |
| spellingShingle | Dept. of Microbiology Human medicine, health, and safety Nordin, Annika Nitrogen based sanitation of source separated faecal matter |
| title | Nitrogen based sanitation of source separated faecal matter |
| title_full | Nitrogen based sanitation of source separated faecal matter |
| title_fullStr | Nitrogen based sanitation of source separated faecal matter |
| title_full_unstemmed | Nitrogen based sanitation of source separated faecal matter |
| title_short | Nitrogen based sanitation of source separated faecal matter |
| title_sort | nitrogen based sanitation of source separated faecal matter |
| topic | Dept. of Microbiology Human medicine, health, and safety |
| url | https://stud.epsilon.slu.se/12404/ https://stud.epsilon.slu.se/12404/ |