Low-Cost Electrode Modification to Upgrade the Bioelectrocatalytic Oxidation of Tannery Wastewater Using Acclimated Activated Sludge

Effective and eco-friendly technologies are required for the treatment of tannery wastewater as its biological toxicity and large volume leads toground water pollution. Hydrophobic (unmodified carbon felt) and hydrophilic modified carbon felt with Linde Type A zeolite (LTA zeolite) and bentonite were examined for their effects on bacterial attachment, current generation, and tannery wastewater treatment efficiency. Chronoamperometry and cyclic voltammetry confirmed the higher electron transfer obtained with modified anodes. Maximum current densities of 24.5 and 27.9 A/m(2) were provided with LTA zeolite and bentonite-modified anodes, respectively, while the unmodified carbon felt gave a maximum current density of 16.9 A/m(2). Compared with hydrophobic unmodified carbon felt, hydrophilic modified electrodes increased the exploitation of the internal surface area of the 3D structure of the carbon felt by the electroactive biofilm. The study revealed 93.8 +/- 1.7% and 96.3 +/- 2.1% of chemical oxygen demand (COD) reduction for LTA zeolite and bentonite, respectively. Simultaneous chromium removal was achieved with values of 94.6 +/- 3.6 and 97.5 +/- 2.2 for LTA zeolite and bentonite, respectively. This study shows the potential approach of carbon felt clay modification for the efficient tannery wastewater treatment using bioelectrochemicals systems (BESs) accompanied with high current recovery.