Composting human waste from waterless toilets J F

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 3 rd. International Conference on Ecological Sanitation, Durban May 24. 2005

Vent pipe Composting toilet Collection/composting compartment Liquid overflow collection

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

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

Composting toilet at roadside facility - Sweden Clean odourless toilets

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/tidslinjeh endelse_view? geografi=&hovedemne=&underemne=&hovedep oke=&underepoke=& and http: //www. adlibris. com/no/product. aspx? isbn=8292309020

Secondary composting

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

NH 3 Composting toilet • Nitrogen loss • To wet/dry • Hygiene

Composting toilet • Nitrogen loss • To wet/dry • Hygiene To much liquid

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

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

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

Secondary composting Composting bioreactor Final hygienized product

Secondary composting Compost laboratory

The compost bioreactor Return of process water - rich in NH 4+ Total volume 750 liter Compost x Liquid container Screen Vacuum pump

Input to the composting bioreactor

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

Temperature in compost vs. time Temp o. C Days

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

Temperature vs. time

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

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

Temperature vs. time and addition of process water

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

Ammonia volatilization NH 3 NH 4 +

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

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

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

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

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

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

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

Conclusions • Secondary composting opens for professional collection and treatment of material from composting toiletsthus reducing risk

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, 68 p. Del Porto, D. and Steinfeld, C. (2000). “The Composting Toilet System Book”. Ecowaters Books, Concord, Massachusetts.