Electro-oxidation Process for the Disinfection of Hospital Wastewater

Abstract

This study investigates the use of electrooxidation (EO) in wastewater treatment, utilizing both batch and continuous once-through processes. Electrochemical methods offer a promising decentralized approach for eliminating microbial contaminants from wastewater. The technology employs mixed metal oxide (MMO) anodes, composed of titanium, ruthenium, iridium, and platinum oxides, which provide excellent stability. A lab-scale EO reactor was used to optimize process parameters—such as NaCl concentration, current density, and treatment duration—through response surface methodology. The technology is particularly suited for post-treatment in sewage plants, aiming to prevent microbial contaminants from entering the environment and reducing epidemic risks. In lab-scale experiments, the EO system's ability to inactivate eight different bacterial species was tested under batch conditions. The findings demonstrated complete bacterial inactivation 100% in simulated water under optimized conditions, which included a current density of 2.38 mA/cm², a NaCl concentration of 1 g per 450 mL, and a treatment duration of 2 min. The bacterial removal efficiency was assessed based on the percentage of inactivation and energy consumption, while also examining the breakdown of organic matter. A pilot-scale study was conducted with actual sewage samples (10-50 L) to assess the MMO anodes' effectiveness in inactivating bacteria. Furthermore, a continuous once-through EO treatment was tested under optimized conditions. The research demonstrated that electrooxidation could efficiently treat hospital wastewater by rapidly inactivating bacteria and degrading organic pollutants. Key findings showed a 99% bacterial inactivation rate at a minimal electrolyte dosage (0.025 g/L), and a short treatment time (2 min), with energy consumption of 0.0322 kWh/m³ and an operational cost of $1.8864/m³. Biological tests, including potassium ion leakage, trypan blue staining, total coliform count, and FE-SEM imaging, confirmed bacterial inactivation. The MMO anodes exhibited remarkable durability, maintaining performance over 350 cycles, highlighting electrooxidation's potential as a scalable and efficient solution for decentralized wastewater treatment in healthcare settings. This method not only enhances environmental protection but also supports public health efforts.