MMO induced batch and pilot-scale electro-oxidation treatment of municipal wastewater

Abstract

The present research aimed to explore the durability of MMO electrodes through electro-oxidation (EO) in purifying secondary treated actual sewage wastewater using batch and pilot-scale setups. The main aim is to inactivate bacteria in sewage treatment plants before they are released into the environment, thus contaminating water and soil. Process parameters such as current density (j), NaCl dose (n), and treatment time (t) were optimized using response surface methodology in a lab-scale EO reactor under batch conditions. The results showed that optimization of current density at 5.90 mA/cm² and NaCl concentration at 1.31 g/L led to 93.90% of bacterial inactivation (Q₁) within 8 min of treatment and 0.48 kWh/m³ energy consumption (Q₂). Biological analysis was conducted to validate bacterial cell destruction and count coliform bacteria in the EO-treated sewage wastewater. XRD, cyclic voltammetry studies, and FE-SEM/EDS analysis were done to confirm the MMO anode’s durability and stability after 100 recycles. The study prioritized bacterial inactivation along with organic matter degradation. Besides that, a small pilot-scale study on the actual sewage wastewater with a volume of 10–50 L was done in batch mode under previously optimized conditions to analyze the efficacy of the MMO anodes in terms of bacterial inactivation.