Effect of initial pH on short chain fatty acid production during the anaerobic fermentation of membrane bioreactor sludge enhanced by alkyl polyglcoside

Abstract

Membrane bioreactor (MBR) sludge anaerobic fermentation for short chain fatty acid (SCFA) production has drawn much attention as it can produce value-added product and reduce sludge volume simultaneously. However, SCFA production from sludge is always limited due to the low hydrolysis rate and rapid consumption by methanogens. In this study, an efficient and green strategy was developed by adding biosurfactant alkyl polyglycoside (APG) into MBR sludge to enhance SCFA production. Experimental results showed that the yield of SCFA reached 282.9 mg chemical oxygen demand (COD)/g volatile suspended solids (VSS) with the optimum APG dosage of 0.2 g/g dry sludge (DS), which was 4.8-fold of the blank. Furthermore, the effect of initial pH ranging from 4 to 12 on SCFA production in the presence of APG was also studied. Results showed SCFA productions from MBR sludge in the presence of APG at initial alkaline pH values were more efficient than those at acidic and near-neutral pH values, and the optimum initial pH was 11.