Simultaneous energy production, boron and COD removal using a novel microbial desalination cell

Abstract

This paper investigates simultaneous boron removal from aqueous solutions, organic matter removal from industrial wastewater and energy production using a Microbial Desalination Cell (MDC). Anode chamber of the conventional MDC cell was modified to include 3D cubic electrodes as a novel design. Effects of operating parameters, including electrode type (3D-electrode and 2D-electrode), anolyte solution temperature (20 °C, 40 °C, and 60 °C), and activated sludge:wastewater volumetric ratio (S:WW = 1:1, 1:2, and 1:5), on MDC performance were studied. Furthermore, real geothermal water treatment was investigated under optimum operating conditions. Boron and organic matter removal efficiencies and the produced power density results were promising for 3D-electrodes under optimum operating conditions. The maximum boron removal efficiency, COD removal efficiency, and power density were 55.5%, 91.5%, and 9.04 mW/m3 treating real geothermal water at optimum operating conditions. The analyses of Scanning Electron Microscope with Energy Dispersive X-ray spectrometer (SEM-EDX) demonstrated biofilm formation and salt deposition on membrane surfaces, which most probably reduced the performance of MDC. Consequently, our results showed that use of 3D-electrodes was a promising improvement to the conventional configurations with 2-D electrodes since removal efficiencies and energy production were comparable for a more compact electrode structure.