Effect of Hydrogen Peroxide on Biohydrogen Production from Melon Fruit (Cucumis melo L.) Waste by Anaerobic Digestion Microbial Community

Biohydrogen (H-2) production has the potential to provide clean, environmentally friendly, and cost-effective energy sources. The effect of increasing oxidative stress on biohydrogen production by acid-treated anaerobic digestion microbial communities was studied. The use of varying amounts of hydrogen peroxide (H2O2; 0.1, 0.2, and 0.4 mM) for enhancing hydrogen production from melon fruit waste was investigated. It was found that H2O2 amendment to the H-2-producing mixed culture increased hydrogen production. Treatment with 0.4 mM H2O2 increased cumulative H-2 output by 7.7% (954.6 mL/L), whereas treatment with 0.1 mM H2O2 enhanced H-2 yield by 23.8% (228.2 mL/gVS) compared to the untreated control. All treatments showed a high H-2 production rate when the pH was 4.5 - 7.0. H2O2-treated samples exhibited greater resilience to pH reduction and maintained their H-2 production rate as the system became more acidic during H-2 fermentation. The application of H2O2 affected the volatile fatty acid (VFA) profile during biohydrogen fermentation, with an increase in acetic and propionic acid and a reduction in formic acid concentration. The H2O2 treatment positively affects H-2 production and is proposed as an alternative way of improving H-2 fermentation..