Elucidating the role of pH and total solids content in the co-production of biohydrogen and carboxylic acids from food waste via lactate-driven dark fermentation

Notwithstanding lactate-driven dark fermentation (LD-DF) can cope with inhibition issues associated the over-proliferation of lactate producers, there is still a knowledge gap about role key operational parameters. In this study, effect pH and total solids (TS) content on co-production hydrogen carboxylic acids, including medium-chain acids (MCCAs), from food waste (FW) via LD-DF was investigated. A series batch fermentations conducted, first, without control, then at fixed values 5.5, 6.0 6.5, while maintaining constant TS 5 %. It observed that higher pH, lower accumulation extent rate production, sustaining maximum production yield 81 NmL/g VS fed 9 NL/L-d, respectively, 6.5. second tests, adjusted to 5, 7.5 10 % set The highest performance (103 NmL/g-VS 13.3 NL/L-d) achieved TS, which also resulted in MCCAs, particularly caproate, an titer 8.7 g/L. Hydrogen plateaued exhaustion regardless condition tested. Further assessment through biochemical methane potential tests showed effluents be alternatively valorised into biogas. Overall, results obtained confirmed FW suggested non-conventional route may alternative approach flux diverted toward undesirable non-hydrogen-producing metabolic pathways.