Methanogenesis Performance Enhancement Of Municipal Sludge Anaerobic Digestion Based On Substrate Conditioning

Anaerobic digestion of sludge is the crucial way to achieve its reduction,stabilization and resource utilization.But the overall development of anaerobic digestion is sluggish due to low efficiency of organic matter degradation and gas production when the sludge going through anaerobic digestion alone.So it's meaningful to improve methane anaerobic digestion efficiency.In this study,municipal sludge was taken as matrix.CSTR reactor was used for semi continuous test,including sludge combined with kitchen waste,sludge adding residue of hydrogen production,thermo-hydrolyzed sludge combined with mesophilic anaerobic digestion and thermo-hydrolyzed sludge combined with kitchen waste.The influence of different residence time on the efficiency of gas production was tested and the matrix conditioning method was selected to determine the optimum process for engineering demonstration.The result showed that sludge through matrix conditioning can increase the methane productivity and the degradation rate of organic matter.Thereinto,these indice in SRT=20 d turn out to be better than that in SRT=15 d.SRT=20 d,When the ratio of sludge to the remainder yielded from hydrogen production was set to 1:1,the system run till better than other approaches,and methane's productivity was 422.8 L/(kg·VS)which was 4.1 times that of the raw sludge(102.1L/(kg·VS)).The gas production between raw sludge and thermo-hydrolyzed sludge combined with kitchen waste was almost the same,namely,252.0 L/(kg·VS)and 250.3 L/(kg·VS),The efficiency of thermo-hydrolyzed sludge separate fermentation was not obvious,and its methane productivity was 145.9 L/(kg·VS),which was 1.4 times that of the methane productivity of raw sludge digestion.In the view of the degradation rate of VS and TCOD,it can be summed up as the following order:the thermo-hydrolyzed sludge combined with kitchen waste>raw sludge combined with residue of hydrogen production ? raw sludge combined with kitchen waste>thermo-hydrolyzed sludge>raw sludge.As for the system stability,the raw sludge combined with kitchen waste has the highest system stability,while the raw sludge combined with kitchen waste has the lowest system stability.The maximum gas production rate was 4591.7 L/d during the demonstration operation period of low temperature thermal hydrolysis sludge project.