To exclusively assess biodegradability of domestic wastewater, and the effects of alkalinity and particulates on current density, a dual-chamber MXC was operated with acetate medium, and filtered and raw domestic wastewater as alkalinity concentration was varied. A dual chamber microbial electrochemical cell (MXC) was used for this study. Briefly describing MXC design, two cylindrical plexiglass tubes consisted of anode and cathode chambers, and anion exchange membrane was placed between the two chambers. By integrating carbon fibers with a stainless steel current collector, the anode surface

area per membrane was increased at 1600 m2/m2 approximately, along with electrode distance less than 1 cm. The literature [2] provides detailed information on MXC configuration; current density was expressed LBH589 datasheet per the surface area of the membrane for simplicity in this study. Recycle activated sludge (RAS) was collected from the Waterloo Wastewater Treatment Plant (Waterloo, Ontario, Canada) to inoculate the MXC. 15 mL of RAS was added to the anode chamber, the chamber was sparged with ultra-pure nitrogen (99.999%) for 20 min, and then acetate medium (25 mM

sodium acetate) was fed to the MXC as the electron donor and see more carbon source. The composition of the acetate medium was (per litre of 18.2 MΩ cm MilliQ water) 2050 mg CH3COONa, 2274 mg KH2PO4, 11,678 mg Na2HPO4∙12H2O, FeCl2∙2H2O 3.255 mg, 18.5 mg Na2S∙9H2O, 840 mg NaHCO3, 37 mg NH4Cl, 25 mg MgCl2∙6H2O, 6 mg MnCl2∙4H2O, 0.1 mg CuSO4∙5H2O, 0.1 mg Florfenicol Na2WO4∙2H2O, 0.1 mg NaHSeO3, 0.01 mg CaCl2∙2H2O, 0.5 mg ZnCl2, 0.1 mg AlK(SO4)2, 0.1 mg H3BO3, 0.1 mg Na2MoO4∙2H2O, 0.2 mg NiCl2, 5 mg EDTA, 1 mg CO(NO3)2∙6H2O, 0.2 mg NiCl2∙6H2O.

To mitigate contamination during experiments the medium was autoclaved and then sparged with the ultra-pure nitrogen for 30 min before being fed to the MXC. Medium pH was constant at 7.5 ± 0.15. A reference electrode (Ag/AgCl reference electrode, MF-2052, Bioanalytical System Inc. USA) was placed within ∼1 cm distant from the anode to fix the anode potential at −0.4 V vs. Ag/AgCl reference electrode using a potentiostat (BioLogic, VSP, Gamble Technologies, Canada). The cathode chamber was filled with tap water in which hydrogen gas is produced. Under this potentiostat mode, cathode potential responds to current density and overpotentials in the MXC [17] and [35]. The applied voltage (cathode potential–anode potential) was constant at 0.85 ± 0.5 V during the acclimation phase. Electrode potentials and currents were recorded at every 60 s using EC-Lab for windows v 10.23 software in a personal computer connected with the potentiostat. The MXC was mixed at 150 rpm using a multi-position magnetic stirrer (Model 650, VWR International Inc. Canada), and operated in a temperature-controlled room at 25 ± 1 °C.