Evaluation of pretreatment potential and hydrogen recovery from lignocellulosic biomass in an anoxic double-staged bioelectrochemical system

Abstract The possible impact of bio and electrochemical reactions during pretreatment of rice straw using solvents, sulphuric acid (SA), ammonia (AM), sodium hydroxide (NA), and distilled water (W) was investigated. The total volatile fatty acids (tVFAs) of 163.48 ± 10.49 mM in the electrochemical pre-treatment in the presence of sodium hydroxide (ENA) followed by sulfate-reducing bacteria (EBA) (140.88 ± 0.07 mM) indicating the involvement of electrolytic breakdown of lignocellulosic biomass. The hydrogen production of 0.224 ± 0.05 and 0.218 ± 0.10 mM/g of the substrate was found in the ENA and anoxic sodium hydroxide pre-treatment (CNA) respectively. There was no detectable gasification in SA and AM electrochemical pre-treatments. The major advantage of the electrochemical process is the formation of acetic acid at a lower temperature, whereas processes like autohydrolysis form it at high temperatures during stream explosion pretreatment. The hydrogen production of 1.26 mM/g was found from anoxic hydrolysate pretreated (ECP) rice straw. The SEM and FTIR analysis show distortion of outer layers of biomass in the electrochemical pretreatment (ECP) system, which improved its accessibility towards enzymes for value-added product recovery.