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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 Technologies that emerge from applying ecological thinking to engineering 3rd. International Conference on Ecological Sanitation, Durban May
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Composting toilet Vent pipe Collection/composting compartment
Liquid overflow collection
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Composting toilet cottages (500 000 cottages)
Major toilet type in Norwegian cottages ( cottages) Commonly used in rural homes in Norway Used in many other settings world wide
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Composting toilet at roadside facility - Sweden
Elected the best roadside facility In Sweden 2002
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Composting toilet at roadside facility - Sweden
Clean odourless toilets
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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: and
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Secondary composting
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Composting toilet Volume reduction: 70 - 90% 550 down to 55 liters
(Del Porto and Steinfeld 2000)
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NH3 Composting toilet Nitrogen loss To wet/dry Hygiene
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Composting toilet Nitrogen loss To wet/dry Hygiene To much liquid
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Composting toilet Nitrogen loss To wet/dry Hygiene
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Composting toilet Nitrogen loss To wet/dry Hygiene - no system
above 43oC* - risk of handling (* Engen 1991)
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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
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Secondary composting Composting bioreactor Final hygienized product
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Secondary composting Compost laboratory
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The compost bioreactor
Return of process water - rich in NH4+ Total volume 750 liter Compost x Liquid container Vacuum pump Screen
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Input to the composting bioreactor
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Influence of time and temperature on destroying pathogens in excreta
(Feachem et al. 1983)
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Temperature in compost vs. time
Temp oC Days
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Results Temp vs.time Run no.1 Temp vs.time Run no.2
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Temperature vs. time
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The compost bioreactor - process control
Return of process water amount and frequency Compost x Liquid container Vacuum pump Screen
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The compost bioreactor - process control
Return of process water amount and frequency Compost x Liquid container Vacuum pump Screen
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Temperature vs.time and addition of process water
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The compost bioreactor - process control
Pumping frequency x Liquid container Vacuum pump Screen
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Ammonia volatilization
NH3 NH4 +
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The compost bioreactor - process control
Recycling of process water Controlling air flow Addition of bulking material
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The compost bioreactor - process control
Recycling of process water Controlling air flow Addition of bulking material Manual mixing
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Conclusions A composting bioreactor for processing of human excreta with other biodegradable organic waste is developed x Compost
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Conclusions The composting bioreactor reduce the nitrogen loss compared to windrow composting, thus producing a more valuable compost x Compost
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Conclusions Secondary composting can produce a safe soil amendment in about two months – in contrast to the generally recommended six months
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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
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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
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Conclusions Secondary composting opens for professional collection and treatment of material from composting toilets- thus reducing risk
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References: Engen, Ø 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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