Temperature-phased anaerobic digestion (TPAD) to obtain Class A biosolids. A discontinuous study.
Thermophilic-mesophilic-phase anaerobic digestion assays were carried out in three discontinuous reactors: R1, R2 and R3, which were in thermophilic conditions (55 degrees C) during 2, 4 and 6 days, respectively. After the first stage, the temperature was reduced to 35 degrees C, and at the end of the two-stages, the R2 and R3 systems achieved volatile solid reductions of 45% and 52%, respectively. Faecal coliforms and Salmonella spp. densities below 1000 MPN/g TS and 3MPN/4 g TS, respectively, were also observed. The highest methane yield and the best dewaterability were obtained for R3: 193 mL CH(4)g(-1) VS(added) and 3 min of time-to filter. For R2 and R1, 133 and 97 mL CH(4)g(-1) VS(added), and 4 and 9 min, respectively, were obtained. Although the best results were achieved maintaining thermophilic conditions during the 6 days; however, to take Class A-cataloguing product, for agrarian ends, 4 days operating under thermophilic conditions was sufficient.
Riau
Víctor
V
Department of Environmental Technologies, Faculty of Sea and Environmental Sciences, University of Cádiz, 11510 Puerto Real, Cádiz, Spain.
de la Rubia
M Angeles
MA
Pérez
Montserrat
M
D001421:Bacteria, Anaerobic / Q000378:metabolism*; D019149:Bioreactors / Q000382:microbiology*; D044367:Phase Transition; D012722:Sewage / Q000382:microbiology*; D013696:Temperature; D014874:Water Pollutants, Chemical / Q000302:isolation & purification / Q000378:metabolism*; D018508:Water Purification / Q000379:methods*
D012722:Sewage; D014874:Water Pollutants, Chemical