Enhanced short-chain carboxylic acids yield in dark fermentation by cyclic product removal

Disposal of carbon-rich wastes, such as food waste, is one of the several environmental concerns raised nowadays. Conversion of organic residues by dark fermentation produces short-chain (C₁–C₆) carboxylic acids, which are valuable chemical building blocks. The objective of this study was to optimize the operational parameters and perform comparative studies of cyclic and batch mode dark fermentation for carboxylic acid production from food waste. A maximum yield of short-chain carboxylic acids (SCCAs) 0.21 ± 0.012 g-SCCAs/g-TS in 50 g-TS/L was obtained in the cyclic mode as compared with the 0.13 ± 0.011 g-SCCAs/g-TS in the batch mode. The results showed that the use of the cyclic mode increased the carboxylic acid yield from 54 (batch mode) to 88%.