Ambient temperature treatment of low strength wastewater using anaerobic sequencing batch reactor

Low strength wastewater having chemical oxygen demands (GOD) concentrations of 1000, 800, 600 and 400 mg/l were treated at 35, 25, 20 and 15 degrees C using four anaerobic sequencing batch reactors (ASBRs). Reactor 1 was operated at hydraulic retention time (HRT) of 48 h, reactor 2 at 24 h HRT, reactor 3 at 16 h HRT and reactor 4 at 12 h HRT. 80 to 99% soluble COD was removed at the various operational conditions, except during 15 degrees C treatment of 1000 and 800 mg/l COD wastewater at 12 h HRT and 1000 mg/l COD wastewater at 16 h HRT, where excessive loss of biological solids occurred. The ASBR process can be an effective process for the treatment of low concentrated wastewaters which are usually treated aerobically with large amount of sludge production and higher energy expenditures.