Photo-fermentation biohydrogen production and electrons distribution from dark fermentation effluents under batch, semi-continuous and continuous modes.

In this work, the influence of batch, semi-continuous and continuous mode on biohydrogen production from dark fermentation effluents (DFEs) as substrate and electron distribution was investigated. Results indicated a better H2 production performance was obtained in semi-continuous mode. 50% decanting volume ratio (DVR) and 24 h feeding interval time (FIT) were found to be the best condition. Maximum average H2 production rate (HPR) and H2 yield were obtained of 8.44 mL/h and 1386.22 ± 44.23 mL H2/g TOC, respectively. 37.71% substrate electrons partitioning to hydrogen were detected. For continuous mode, more substrate electrons were diverted toward SMPs with the increasing of HRT due to the fact that longer cell retention, more chances were provided for cell lysis. The bad performance in batch mode ascribed to 56.39% substrate electrons were transferred to cell growth and soluble microbial products (SMPs).