A preliminary study: Microbial electrolysis cell assisted anaerobic digestion for biogas production from Indonesian tofu-processing wastewater at various Fe additions

Tofu-processing wastewater (TPW) is very abundant in Indonesia. This study aimed to examine the impact of Fe additions (0–600 mg-FeCl3/L) on biogas yield from TPW through anaerobic digestion (AD) without and with microbial electrolysis cells (MEC). The presence of MEC in AD increased biogas yield by 14.4–114.5 %. The optimum Fe addition either in AD or MEC-AD was 400 mg-FeCl3/L. Prediction accuracy was higher for the modified Gompertz model compared to first-order and modified Logistic models because it had a higher R2 (0.9942). The presence of MEC in AD increased ym, μ, and λ values. MEC-AD resulted in pollutant removal efficiencies 1.09 to 1.63 times higher than AD. Based on energy analysis, AD and MEC-AD resulted in surplus energy of 3582.1 and 5325.1 J, respectively. It means that the presence of MC in AD successfully increased the surplus energy by about 1.5 times.