| dc.description.abstract |
The Anaerobic Digestion Pasteurization Latrine (ADPL) is a self-contained and energy neutral on-site sani-
tation system using anaerobic digestion of fecal sludge to generate biogas and then uses the biogas to pasteurize
the digester effluent at 65—75°C to produce a safe effluent that can be reused locally as a fertilizer. Two ADPL
systems were installed on residential plots with 17 and 35 residents in a peri-urban area outside of Eldoret,
Kenya. Each system comprised three toilets built above a floating dome digester and one heat pasteurization
system to sanitize the digested effluent. ADPLs are simple systems, with no moving parts and relying on
gravity-induced flows. Adoption at the two sites was successful, and residents reported that the systems had
little to no odor or flies. ADPLs were monitored for biogas production and temperatures in the pasteurization
system. ADPLs serving 17 and 35 residents produced on average 16 and 11 Lbiogas/person/day (maximum of 20
and 15 Lbiogas/p/d), respectively. The temperature in the sterilization system was greater than 65°C on 58% and
87% of sampling days during the most stable period of operation. Treated effluent was analyzed periodically for
chemical oxygen demand (COD), biochemical oxygen demand (BOD), total ammonia nitrogen (TAN), pH, and
fecal coliform (FC). On average, the effluent at the two locations contained 4,540 and 6,450 mg COD/L (an
85% or 89% reduction of the estimated input), 2,050 and 3,970 mg BOD/L, and 2,420 and 4,760 mg NH3-N,
respectively, and greater than 5 log reductions of FC (nondetectable) in the sterilization tank. Results from this
field study show that anaerobic digestion of minimally diluted fecal sludge can provide enough energy to
pasteurize digester effluent and that the ADPL may be a suitable option for on-site fecal sludge treatment. |
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