Investigation of the effects of different conductive materials on the anaerobic digestion

In recent years, the efforts of enhancement of the transformation of organic matter into methane have intensified and direct interspecies electron transfer (DIET) mechanisms have great importance in this regard. In this study, magnetite, graphite powder, activated carbon and iron (II) sulfate were used to investigate DIET mechanisms during the conversion of glucose into methane. Obtained methane gas measurements at the end of the 30-day incubation period (37 +/- 1 degrees C) were evaluated with the modified Gompertz model, first-order kinetic model and two-stage first-order kinetic model. Maximum total and soluble COD removal efficiencies were observed in the magnetite-added R2 reactor (73.75% and 90.68%, respectively). While there was no significant difference in terms of cumulative methane gas measurements, a significant decrease was observed in the lag phase time for the magnetite-added R2 reactor (reduced by half) with regard to the modified Gompertz model. According to the first-order kinetic model, the maximum conversion rate of glucose into methane and the peak methane production rate were observed in the graphite powder-added R3 reactor (k = 0.1744 day(-1) and 93 mL/day). According to the two-stage kinetic model, the maximum methanation rate was observed in the magnetite-added R2 reactor (k(2) = 0.7223 day(-1)). The sludge in the magnetite-added R2 reactor has best settleability (SVI = 53.4 mL/g).