Improving Acetate Production From Sewage Sludge By Coupled Syntrophic Acetogenesis With Homoacetogenesis Process

A novel coupled syntrophic acetogenesis with homoacetogenesis process was used to produce acetate from sewage sludge by anaerobic fermentation. Effects of different process parameters (pH,inoculums sludge concentration,substrate concentration)on the efficiency of acetate and gas production from excess sludge were investigated, we have the most suitable conditions for acetate and gas production. And then the different of acetate production by A phase pH and temperature regulation was studied in the fermentor of coupled syntrophic acetogenesis with homoacetogenesis process. Finally, optimal parameter of coupling system was obtained Results were shown as follows:(1). Effects of different process parameters (pH,inoculums sludge concentration,substrate concentration)on the efficiency of acetate and gas production from excess sludge were investigated under non-coupled state. The result showed that pH = 9.0 is the most suitable condition for acetate production; pH = 7.0 is the most suitable condition for gas production. Average yield were 35.5 mL/L/d and 0.54 g/L/d respectively; The most suitable concentration of inoculums sludge for acetate and gas production was 8 g/L, average yield were 25 mL/L/d and 0.57 g/L/d respectively; The most suitable concentration of substrate for acetate and gas production was 30 g/L, average yield were 0.23 g/g SCOD and 0.41 g/g SCOD。Respectively.(2). According to the results of pH regulation from 9.0 to 7.0 and then back to 9.0 by the coupling system, when the coupled system run at pH 9.0 and 7.0 the total acetate production reached 47.9 g and 35.1 g respectively. The former is 36.5% higher than the latter. We demonstrated that regulation of pH in the coupling system can improve the VFA production and realize selective acetate accumulation from sludge anaerobic fermentation.(3). According to the results of temperature regulation from 35℃to 50℃by the coupling system, when the coupled system run at temperature 35℃,45℃and 50℃the total acetate production reached 43.9 g,36.7 g,18.4 g respectively. The most suitable temperature for acetate production was 45℃due to product inhibition. The former is 36.5% higher than the latter. We demonstrated that regulation of pH in the coupling system can improve the VFA production and realize selective acetate accumulation from sludge anaerobic fermentation.