Revealing the Underlying Mechanisms of How Sodium Chloride Affects Short-Chain Fatty Acid Production from the Cofermentation of Waste Activated Sludge and Food Waste

Abstract

Recently, anaerobic cofermentation of waste activated sludge (WAS) and food waste for short chain fatty acid (SCFA) production has drawn growing attention. However, the details of how sodium chloride (NaCl) in food waste affects SCFA generation from the cofermentation remain largely unknown, which provides limited understanding of the cofermentation process. This work therefore aims to provide such support. Experimental results showed that the effect of NaCl on SCFA production was dosage dependent. With the increase of NaCl level from 0 to 8 g/L SCFA production increased from 367.6 to 638.5 mg chemical oxygen demand (COD)/g of volatile suspended solids (VSS). However, further increase of NaCl caused severe inhibition of SCFA production. The presence of NaCl not only accelerated the release of soluble substances from food waste and disruption of both extracellular polymers and cell envelopes in sludge but also promoted the conversion of protein released from the disintegration process, thereby causing more...