Performance characterization of anaerobic sequencing batch reactor processfor digestion of night soil

Laboratory experiments were conducted to investigate the performance of an anaerobic sequencing batch reactor (ASBR) process for night soil treatment. Performances of the reactors were evaluated at an equivalent hydraulic ret ention time (HRT) of 10 days with an equivalent loading rate of 2.6 kgVS/m( 3)/d (3.1 kgCOD/m(3)/day) at 35 degreesC, Digestion of a night soil was pos sible using the ASBR at an HRT of 10 days in spite of high concentration of ammonia nitrogen and settleable solids. Solids were accumulated rapidly in the ASBRs, and their concentrations were 2.3 similar to2.4 times higher th an that in a completely mixed control reactor. Remarkable increases in gas production were observed in the ASBRs compared with the control reader. Ave rage increases in equivalent daily gas production from the ASBRs were 205 s imilar to 220% compared with that from the control run. The ASBR with react ion period/thickening period ratio (R/T ratio) of 1 showed a little higher gas production and organic removal efficiency than that with R/T ratio of 3 . Volatile solids removals based on supernatant of the ASBRs were 12 simila r to 14% higher than that of the control reactor. Thus, the ASBR was a stab le and effective process for the treatment of night soil having high concen tration of settleable organ ics and ammonia nitrogen.