Relationship analysis of anaerobic fermentation parameters exposed to elevated chromium (VI)

Heavy metals may affect anaerobic fermentation processes, which could result in variations in anaerobic fermentation parameters. In the present study, the impact of changing hexavalent chromium (Cr6+) concentrations on different anaerobic fermentation parameters was investigated. The results showed that adding Cr6+ affected fermentation efficiency since it elicited changes in enzyme activity as well as metabolic pathways. Adding Cr6+ (30 mg/L) resulted in significant positive correlation between coenzyme F420 activities, CH4 contents, and cumulative biogas yields. The results suggested Cr6+ enhanced biogas production by promoting the activity of coenzyme F420. Increasing the concentration of Cr6+ to 100 mg/L resulted in a significant correlation (P < 0.01) between the CH4 contents and cumulative biogas yields and oxidation–reduction potential and pH. At high concentrations, Cr6+ (500 mg/L) elicited parametric relationships dissimilar to those obtained using low Cr6+ concentrations, particularly on the hydrolysis stage. This study comprehensively demonstrated the influence of Cr6+ stress during the anaerobic fermentation process from a new insight and could provide critical references for further experimental design and data monitoring investigations.