Abstract
The treatment of high chemical oxygen demand (COD) industrial effluents remains a critical environmental challenge, particularly when coupled with salinity management. In this research, a microbial desalination cell (MDC) is proposed as a sustainable alternative or pre-conditioning treatment to conventional reverse osmosis (RO) for simultaneous organic load reduction and desalination. The MDC system integrates anodic biodegradation of organic matter with a bio-electrochemical desalination mechanism, thereby eliminating the high energy demand associated with RO. A lab-scale five-chambered MDC was implemented for treating effluent (synthetic wastewater) with a COD of 7.98 ± 0.05 g/L and total dissolved solids (TDS) of 24.05 ± 0.11 g/L, and a NaCl solution of salinity 15 g/L. A metal-organic framework (MOF) based catalyst (ZIF8 – ZIF67) was synthesised and coated over the cathode to enhance the charge transfer mechanism and consequently the ORR of the MDC. The electrochemical properties of the catalyst were recorded through electrochemical characterisation, topography, and elemental composition through scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis, and the material’s crystal structure through X-ray diffraction (XRD) analysis. The applied cathode catalyst resulted in 78.8 ± 2.5 % of COD removal, 81.8 ± 3.2 % of TDS removal, and 86.4 ± 1.7 % of desalination efficiency. Simultaneously, the maximum operating voltage recorded was 303 ± 8.9 mV across a 100 O external resistor of the MDC. The maximum power density and coulombic efficiency noted during the investigation were 608.3 mW/m2 and 11.29 %, respectively. This method showed a promising way to achieve energy-efficient, carbon-neutral, and cost-effective wastewater treatment.
