Abstract
AbstractOne-stage autothermal thermophilic aerobic digestion (ATAD) is a promising process for sewage sludge stabilization. This study investigated semicontinuous operation in simulated one-stage ATAD digesters and analyzed the effects of hydraulic retention time (HRT) on sludge stabilization. During semicontinuous operation, the average volatile solids (VS) removals at HRTs of 13 and 16 days were 40.1% and 41.8%, respectively. Because HRTs were 6 and 10 days, the maximum VS removal was no more than 33.2%, less than 38% required by Class A digested sludge, so a suitable HRT level is 13–16 days for a one-stage ATAD system. The digesters with 13- and 16-day HRTs maintained relatively low soluble chemical oxidation demand (SCOD), total nitrogen, NH4+-N, and total phosphate, whereas the digester at HRT 6 days had high SCOD concentration (<6,300 mg L−1) and low oxidation reduction potential (ORP), ranging between −335 and −245 mV. Volatile fatty acids (VFAs) accumulated rapidly at short HRTs, and acetic, pro...
Published Version
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