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Composting human waste from waterless toilets

Composting human waste from waterless toilets. J. F. Hanssen*, A. Paruch**, P. D. Jenssen** * Department of Biotechnology and Chemistry ** Department of Mathematical Sciences and Technology The Norwegian University of Life Sciences.

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Composting human waste from waterless toilets

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  1. Composting human waste from waterless toilets J. F. Hanssen*, A. Paruch**, P. D. Jenssen** * Department of Biotechnology and Chemistry ** Department of Mathematical Sciences and Technology The Norwegian University of Life Sciences 3rd. International Conference on Ecological Sanitation, Durban May 24. 2005

  2. Vent pipe Composting toilet Collection/composting compartment Liquid overflow collection

  3. Composting toilet • Major toilet type in Norwegian • cottages (500 000 cottages) • Commonly used in rural homes • in Norway • Used in many other settings • world wide

  4. Composting toilet at roadside facility - Sweden Elected the best roadside facility In Sweden 2002

  5. Composting toilet at roadside facility - Sweden Clean odourless toilets

  6. Antartica 2001 The compost reactor presented herein was tested when Erik Sønneland (picture) and Rolf Bae spent almost one year on the south pole preparing for crossing the whole Antartica. See also: http://www.polarhistorie.no/hendelser/1209014134.59/tidslinjehendelse_view?geografi=&hovedemne=&underemne=&hovedepoke=&underepoke=& and http://www.adlibris.com/no/product.aspx?isbn=8292309020

  7. Secondary composting

  8. Composting toilet • Volume reduction: • 70 - 90% • 550 down to 55 liters (Del Porto and Steinfeld 2000)

  9. NH3 Composting toilet • Nitrogen loss • To wet/dry • Hygiene

  10. Composting toilet • Nitrogen loss • To wet/dry • Hygiene To muchliquid

  11. Composting toilet • Nitrogen loss • To wet/dry • Hygiene

  12. Composting toilet • Nitrogen loss • To wet/dry • Hygiene • - no system • above 43oC* • - risk of handling (* Engen 1991)

  13. Composting toilets - some challenges • Minimize risk when handling/emptying • Ensure a hygienized compost • Minimizing the nitrogen loss during composting of nitrogen-rich waste • Minimizing the odour emission during composting

  14. Secondary composting Composting bioreactor Final hygienized product

  15. Secondary composting Compost laboratory

  16. x Compost The compost bioreactor Return of process water - rich in NH4+ Total volume 750 liter Liquid container Vacuum pump Screen

  17. Input to the composting bioreactor

  18. Influence of time and temperature on destroying pathogens in excreta (Feachem et al. 1983)

  19. Temperature in compost vs. time Temp oC Days

  20. Results Temp vs.time Run no.1 Temp vs.time Run no.2

  21. Temperature vs. time

  22. x Compost The compost bioreactor - process control Return of process water amount and frequency Liquid container Vacuum pump Screen

  23. x Compost The compost bioreactor - process control Return of process water amount and frequency Liquid container Vacuum pump Screen

  24. Temperature vs.time and addition of process water

  25. x Compost The compost bioreactor - process control Pumping frequency Liquid container Vacuum pump Screen

  26. Ammonia volatilization NH4 + NH3

  27. The compost bioreactor - process control • Recycling of process water • Controlling air flow • Addition of bulking material

  28. The compost bioreactor - process control • Recycling of process water • Controlling air flow • Addition of bulking material • Manual mixing

  29. x Conclusions Compost • A composting bioreactor for processing of human excreta with other biodegradable organic waste is developed

  30. x Conclusions Compost • The composting bioreactor reduce the nitrogen loss compared to windrow composting, thus producing a more valuable compost

  31. Conclusions • Secondary composting can produce a safe soil amendment in about two months – in contrast to the generally recommended six months

  32. Recommendations • At least 15 cm of bark should be placed above the filtration screen to enhance leachate drainage. • Food waste should be chopped to at least 5 cm dimensions. • Although meat and fish products can be added, large bones should be removed. • Food waste and excreta should be mixed, not layered. • The leachate evacuation hose should be insulated if exposed to cold temperatures. • The reactor needs weekly maintenance

  33. Further investigations • Different concentrations of leachate recycled at different times • Different volumes of different bulking agents • Different mixing schedules • Investigate dieoff of other organisms than coliforms

  34. Conclusions • Secondary composting opens for professional collection and treatment of material from composting toilets- thus reducing risk

  35. References: Engen, Ø. 1991. Hytteklosetter-Alternative avløpsløsninger for hytter og spredt bebyggelse, med hovedvekt på miljøkonsekvenser. SFT/JORDFORSK report no. 1207, Centre for Soil and Environmental Research, Ås, Norway, 68p. Del Porto, D. and Steinfeld, C. (2000). “The Composting Toilet System Book”. Ecowaters Books, Concord, Massachusetts.

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