Figure 3

Acetate removal efficiency (A), CH4 production rate (B) and effluent pH (C) of R1 and R2 and change of anodic Coulombic efficiency and current of R1 (D) under the acidic conditions (pH: 7.0–5.0). Error bars represent standard deviations of three measurements. (P value [acetate removal] = 0.012957, P value [CH4 production rate] = 0.009679, P value [effluent pH] = 0.009734 based on two tailed student t-test [n = 48]).