Kinetics Study of Sewage Sludge Treatment by an Aerobic Digestion

In this study, a 50 L laboratory scaled Membrane Anaerobic System (MAS) combining ultrafiltration (UF) membrane with anaerobic reactor was used to treat raw sewage sludge. Six steady states were attained as a part of a kinetic study. The three kinetic models (Monod, Contois and Chen and Hashimoto) were successfully fitted. The results of all six steady states were successfully fitted above 98% by Monod, Contois and Chen and Hashimoto. Contois model appeared to be the best at 99.7%. The microbial kinetic constants were Y = 0.74 g VSS g(-1) COD and b = 0.20 day(-1). The minimum solids retention time, f(m(c)(in) obtained from the three kinetic models ranged from 5-16.9 days. The k values were in the range of 0.350-0.519 g COD g(-1) VSS day and k(max) values were between 0.259 and 0.384 day(-1). The Solids Retention Time (SRT) decreased from 1250 days to 16.1 days. The methane gas yield was between 0.19 to 0.54 L g(-1) COD day(-1) when the organic loading rate increased from 0.1 kg COD/m(3)/day to 10 kg COD/m(3)/day. The COD removal efficiency was 96.5-99% with HRT of 7.8 days. And the rage of mixed liquor suspended solids was from 12760 to 21800 mg L(-1).