Augmenting dark fermentation with carbonaceous material for enhanced biohydrogen yield and substrate conversion in whey wastewater treatment

Hydrogen is a promising renewable energy source, available as a substitute for fossil fuels since it has the potential to support sustainable development goals significantly. Dark fermentation (DF) offers several benefits and considerable potential for producing biohydrogen over other methods. However, the biohydrogen yield in DF remains relatively modest. Therefore, this work investigates the carbon felt (CF) bioelectrode amended dark fermentative biohydrogen production from whey wastewater. Employment of different-sized CF (CF–S, CF-M, CF-L) at optimum conditions showed an improved biohydrogen production of 385.7 ± 19 mL for CF-M, 3-fold greater than the control (125.8 ± 6 mL). The highest chemical oxygen demand removal efficiency of 65 % was achieved for CF-M, indicating its effectiveness in converting whey wastewater into biohydrogen. Metabolite analysis revealed that the CF-amended systems followed a butyrate-type metabolic pathway. Further, CF-M has the highest protein (1172.6 ± 58.6 μg/mL), polysaccharide concentration (198.5 ± 9.9 μg/mL), and electron transport system activity (394.08 ± 19.7 μg/mg.h) than other systems, suggesting better enzymatic stability and enhanced electron transfer. Thus, incorporating CF in DF represents an environmentally sustainable approach to enhance biohydrogen production efficiency.