Concomitant hydrogen and butanol production via co-digestion of organic wastewater and nitrogenous residues

Abstract

Hydrogen is recognized as zero-carbon fuel having the highest calorific value per unit mass as compared to other fuels. Butanol is also a promising biofuel having better fuel characteristics as compared to bioethanol. Thus, aim of the present study was concomitant hydrogen and n-butanol production via codigestion of organic wastewater such as cane molasses (CM), distillery effluent (DE) and starchy wastewater (SWW) and nitrogenous residues. The addition of co-substrate to organic wastewater has resulted in 12.2, 1.1 and 6.6 folds increase in hydrogen production in comparison to CM, DE and SWW, respectively as the sole substrate. Maximum energy conversion efficiency and positive net energy gain of 50.16% and 7.29 KJ gCOD−1, respectively were achieved using SWW supplemented with water hyacinth (WH). Acid pretreatment of WH leads to higher hydrogen and butanol production of 3160 mL L−1 and 4.5 g L−1, respectively with 89% energy conversion efficiency. This study shows the suitability of SWW with acid treated WH as feedstock for sustainable and efficient bioenergy generation with an additional advantage of waste management.