Study on inhibition factors of biogas production during anaerobic co-digestion of sewage sludge and waste grease
剩余污泥与废弃油脂混合厌氧消化产气缓滞因素研究

This work studied the inhibition factors of biogas production based on a completely mixed anaerobic digestion reactor, which was applied to the co-digestion of waste activated sludge and the grease from kitchen waste. The percentage of waste grease in the substrate was 30% (in VS), and the ratio of substrate to the inoculum was 1.87 in VS. The concentration of NH4+-N maintained <500 mg·L-1 in the whole process, indicating little negative effect of free ammonia on the specific methane production potential. The accumulation of acetic acid, the principal VFA used by methanogenic bacterias, caused pH decrease and resulted in acidification of the reactor. When pH decreased to 6.4, there was a lag period of 10~15 days of methane production. Then with the degradation of VFAs and buffer by the alkalinity increase, the reactor resumed to the normal state. Different sludge particles developed in the reactor reflected the different stages and acidification conditions.