Enhanced electrochemical disinfection of domestic aquaculture wastewater with energy production in reverse electrodialysis

Abstract

Reverse electrodialysis (RED), based on non-precious electrodes, was applied to disinfect domestic aquaculture wastewater. It was found that treatment could be achieved either by an anodic reaction of electro-generated sodium hypochlorite (NaClO) or via a cathodic reaction of electro-generated hydrogen peroxide (H2O2). Without circulation, the disinfection rate was sub-optimal and depended on the anodic and cathodic reactions, reaching 82 +/- 5% at the anode (0.3-2.9 mg/L of chlorine(DPD), pH 3.2 +/- 0.4) and 59 +/- 7% at the cathode (2.9-8.7 mg/L of H2O2, pH 10.7 +/- 0.3). In contrast, a high removal efficiency of >= 99 +/- 1% was obtained when anodic and cathodic solutions were circulated due to the synergetic effect between HClO and H2O2 (0.1-2.1 mg/L of chlorine(DPD), 3.9-4.9 mg/L of H2O2, pH 7.8 +/- 0.2). Both operating modes resulted in a stable power production of 6 +/- 0.5 W/m(2). These results support the view that RED can offer a cost-effective and energy-efficient option for disinfecting aquaculture wastewater.