Efficient short-chain fatty acids recovery from anaerobic fermentation of wine vinasse and waste activated sludge and the underlying mechanisms

In this study, the efficient recovery of high-quality short-chain fatty acids from wine vinasse and waste activated sludge mixtures was investigated. The highest accumulation of short-chain fatty acids reached 3502 mg chemical oxygen demand per litre with a proportion of 82.5% acetic and propionic acids in the reactor with a wine vinasse/waste activated sludge mixture under optimized fermentation conditions, while merely 236 and 618 mg chemical oxygen demand per litre was accumulated in the reactors with waste activated sludge and wine vinasse systems alone, respectively. The mechanisms of the exceptional short-chain fatty acids promotion were mainly attributed to the simultaneous increase of bioavailable substrates and the fermentative community. The general microbial activity, key enzymes responsible for short-chain fatty acids generation, and diversity and abundance of fermentative bacteria were all enhanced under optimum conditions, which resulted in the rapid hydrolysis and acidification of bioavailable substrates for short-chain fatty acids generation. Moreover, the dewaterability of fermentation residues was also enhanced due to the presence of wine vinasses as skeleton builders.