3. Conclusions
The present study introduced a new method of efficiently and economically enhanced SCFA and bio-methane generation from WAS by low energy consumption pretreatment. With the optimal conditions of low energy consumption pretreatment, i.e., pretreated sludge at 100°C for 60 min and adjusted initial pH 9.0 then fermented for 6 days, the maximal SCFA generation (348.6 mg COD/g VSS) can be reached, which was higher than that reported previously. Besides, acetic acid was found to be the dominant product of the content of 68.2% during the acidogenesis stage and it can be used as the carbon resource to produce methane in the following stage. Further, mechanisms for the low energy consumption pretreatment significantly improving SCFA production were discussed. The largest carbohydrate and protein consumption and the highest activities of the key relevant enzymes were all observed under the optional conditions of low energy consumption pretreatment. In addition, the 16S rRNA gene clone library demonstrated that Porphyromonadaceae, Clostridiaceae, Ruminococcaceae and Clostridiales were the dominant microbial community in this anaerobic digestion system.