Unravelling the Biohydrogen Production Potential from a Co-Digestion Process of Banana Processing Wastewater and Synthetic Sewage by Anaerobic Fermentation: Performance Evaluation and Microbial Community Analysis

Biohydrogen (bioH 2 ) and soluble metabolites products (SMPs) obtention from the co-digestion process of banana processing wastewater (BPW) and synthetic sewage (SS) were investigated. The reactor performance was evaluated by BPW addition with different initial concentrations: 2.0, 5.0, and 9.6 g of total carbohydrate (TC)/L (pure BPW) using SS to complete the working volume. The dark fermentation process was carried out in a 1 L batch reactor operated at 37 °C/52 h and pH 7. The composition of gas and liquid samples (TC, VFAs, alcohols, and pH) were analyzed during reactor operation. The highest bioH 2 production yield (210.82 ± 32.07 NmL/g TC) and bioH 2 production rate (40.93 ± 7.60 NmL/g TC/h) were obtained at an initial substrate concentration of 2.0 g TC/L. These results indicated that the co-digestion improved carbohydrate utilization and induced a more effective metabolic pathway to bioH 2 production. At this condition, the main soluble metabolite products were acetate and butyrate, whereupon Clostridiacae was the main family involved in BPW fermentation. The prediction of functional gene expression evidenced a shift in the mechanisms of SMPs and bio H 2 obtention as the initial concentration of substrate changes. Graphical Abstract