Production of Volatile Sulfur Compounds duringThermophilic Anaerobic Digestion of Municipal WastewaterSludge

摘要

This study compares the effect of a rapid (from 54 to 58℃ in two weeks) and a slow increase ofrnthe thermophilic digester temperature (from 54 to 57℃ at a rate of 0.55℃ per month) on fullscalernthermophilic anaerobic digestion. Rapidly increasing the digester temperature causedrnelevated production of volatile sulfur compounds, most notably methyl mercaptan, whereasrnvolatile solids destruction and methane production were not significantly affected. The increasernof the volatile fatty acid to alkalinity ratio from 0.1 to over 0.3 during the rapid temperaturernincrease indicated a transient biochemical instability, which could be reversed by lowering therntemperature. In contrast, the steady-state test showed no effect on digester performance when therntemperature was slowly increased to 57.2℃ over several months of operation. Production ofrnmethyl mercaptan was detected in trace amounts, but only at the highest temperature testedrn(57.2℃). These tests suggest that the thermophilic digester temperature can be increased to 57℃rnwithout an effect on digester performance by allowing sufficient time for microbial populationsrnto adapt to higher temperatures. Further research is warranted to accurately determine therntemperature limit for thermophilic anaerobic digestion in full-scale applications.