[Research on single phase high solid anaerobic digestion of organic fraction of municipal solid wastes]

Under mesophilic condition (35 degrees C), a bench-scale experiment based on high solid anaerobic digestion process was conducted in a fed-batch single phase reactor to treat the OFMSW. The experiment has lasted for more than half a year and significant results were obtained. At the start-up stage, acidification occurred and showed large inhibition to gas production and the gas production rate once dropped to 0. After pH conditioning, the system has recovered and began to stably running. In this period, gas production rate reached 746.33 L/kg volatile solids (VS) [3.69 L/(L x d)] when the total solids (TS) content of the feeding waste was 24.79% and the VS content was 23.06%. The organic loading rate and hydraulic retention time(HRT) was 4.94 kg/(m3 x d) and 47 d respectively. However, with time went by, accumulated ammonia exceeded its limited value, which is deduced as 2000 mg/L, and the gas production rate dropped below half of the maximum value. By adding chemicals to diminish the amount of ammonia and adjusting the C/N of the feeding, inhibition was relaxed and gas production rate increased gradually.