Development of AFEX-based consolidated bioprocessing on wheat straw for biohydrogen production using anaerobic microflora

Consolidated bioprocessing (CBP) of wheat straw (WS) pretreated via ammonia fiber expansion (AFEX) for hydrogen production was discussed in this study. Results indicate that rotted wood crumb is a good mixed natural-microflora seed source for biohydrogen production from WS. The hydrogen-producing capability of the inoculum could be improved by an enrichment treatment. In order to enhance the digestibility of WS, AFEX pretreatment conditions were investigated. The optimal conditions were determined to be 100 °C, 1:1 (w/w) ammonia to biomass loading, and 30min residence time. The yield of H2 was 67.8% higher using AFEX-pretreated WS than using untreated material. Moreover, degradation products derived from AFEX pretreatment exerted no impact on hydrogen fermentation if controlled below 1.5% substrate-loading-equivalent. In addition, the maximum AFEX-WS conversion and H2 production were achieved at substrate loading of 0.8%. This work indicates that CBP offers a promising platform for direct and cost-effective cellulosic hydrogen production compared to separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF).