A clean biorefinery process for converting corn stover into hydrogen, electricity, and aromatic flavor compounds

Traditional biomass biorefinery typically involves pretreatment, enzymatic hydrolysis, and chemical or biological conversion. This study aims to explore a clean biorefinery approach to convert corn stover into clean energy and aromatics without chemical or physicochemical pretreatment and enzymatic hydrolysis. Firstly, corn stover was anaerobically fermented with Clostridium cellulolyticum under pH-adjusted process, generating a hydrogen yield of 57.2 mL/g stover and soluble organic compounds (SOCs). At a corn stover concentration of 10 g/L, the degradation rates of cellulose, xylan, arabinan, and lignin were 61.4 %, 58.3 %, 79.2 %, and 17.9 %, respectively. Subsequently, SOCs derived from anaerobic fermentation were used as substrates to construct microbial fuel cell (MFC) and microbial electrolysis cell (MEC) using Shewanella putrefaciens. In the MFC system, the open circuit voltage and maximum power density were 0.63 V and 16.9 mW/m2, respectively. In MEC system, when an external voltage of 0.7 V was applied to the circuit, the maximum hydrogen yield at the cathode reached 12.9 mL/g SOCs. After MFC/MEC treatment, SOCs were utilized and valuable aromatic flavor compounds, such as 2-methoxyphenol and α-isomethyl ionone, were produced. Through the biorefinery coupling anaerobic fermentation with MFC/MEC, all components of corn stover were utilized, and hydrogen, electricity, and aromatic flavor compounds were produced.