A 14.7-L, three-chamber anaerobic baffled reactor (ABR) was used to evaluate the treatment of low-strength synthetic wastewater (chemical oxygen demand [COD] of 300 to 400 mg/L) and assess process reactivation after a prolonged period of inactivity. The reactor was inoculated with anaerobic seed and start-up was immediate. At 26°C and hydraulic retention times (HRTs) of 24 and 12 hours, COD removal averaged 87.2 and 91.0%, respectively, and biogas yield for methane (CH 4 ) was 0.184 and 0.102 m 3 CH 4 /kg COD removed, respectively. The ABR was reactivated after two years without feeding. Response was prompt and removal averaged 85.3% even during the initial 10-day period. Lowering temperature to 16°C did not impair removal efficiency at HRTs of 24 and 12 hours. However, biogas release decreased by 30% and apparent COD conversion to methane dropped by 24 and 31%, respectively. At the end of the study, biomass was mostly in the bottom of the reactor and had moved from the first to the second chamber, while organic stabilization was occurring essentially in the first two chambers (56.1 and 22.4%, respectively, in terms of COD). Water Environ. Res., 74, 170 (2002).

No abstract

A study was undertaken to evaluate the anaerobic treatability of different types of olive oil mill wastewater, including raw waste (concentrated or diluted) and pretreated waste containing soluble organics only. Anaerobic treatment of concentrated raw waste in draw and fill digesters operating at organic loading levels up to 4 kg COD/m1·d effected 68-74% mean BOD5 and 78-81% mean COD removals, while treatment of diluted raw waste in the same type digesters fed at a hydraulic detention time of 8 d and organic loading levels up to 3.7 kg COD/m3·d resulted in 83-84% mean BOD5 and 75-77% mean COD removals. Anaerobic treatment of the soluble organics contained in mill wastewater in draw and fill digesters operating under simulated steady state conditions at hydraulic detention times 8-20 d and an organic loading level of 0.8 kg COD/m3·d achieved 72-88% mean BOD5 and 56-70% mean COD removals. The maximum attainable soluble organics removal was found in the range 77-79% for soluble COD and 92-95% for soluble BOD5.

No abstract

Three 12.5‐L upflow‐anaerobic filters (AF), with ceramic‐saddle, plastic‐ring, and crushed‐stone packing, were used to evaluate the sustained treatment of municipal wastewater. The reactors were initially fed dogfood‐fortified wastewater and then raw municipal wastewater, and operated at 25.4°C (32 months) and 15.5°C (2 months). During 23 months, the AF units treated municipal wastewater (mean chemical oxygen demand [COD] 442 mg/L and total suspended solids [TSS] 247 mg/L), the hydraulic retention time (HRT) ranged from 3.1 to 0.30 d (empty bed), and the organic loading rate ranged from 0.115 to 1.82 kg COD/m 3·d. At the higher temperature and an HRT (void volume) of 1.0 d, COD and TSS removals ranged from 74 to 79% and 95 to 96%, respectively; however, efficiencies declined substantially at HRT values less than 0.4 d. Reactor performance, under the same hydraulic and organic loadings, deteriorated with time and was adversely affected by lower temperature.