Analysis and Calculations The biogases produced by MECs were collected by gas bags (0.25 L capacity; Cali-5-Bond, Calibrated Instruments Inc.), with volumes measured regularly by withdrawing the gases using glass syringes, and composition analyzed by a gas chromatography (Agilent 4890D; J&W Scientific, USA) quipped with a thermal conductivity detector (TCD)1. The volumes of H2, CO2, and CH4 were calculated by multiplying the total gas production (sum of measured gas and headspace volume) by their specific fractions. Acetate concentrations in the solution before and after MEC experiments were measured by another gas chromatography (Agilent 7890 A; J&W Scientific, USA) equipped with a flame ionization detector (FID), and a polyethylene glycol: 30 m 횞 0.530 mm 횞 1.00 關m capillary column (Agilent 19095N-123, J&W Scientific, USA) using a nitrogen carrier gas. Cyclic voltammetry (CV) experiments were conducted at a scan rate of 10 mV s?