Electrochemical peroxidation of contaminated aqueous leachate

Abstract

The landfill process for disposal of domestic waste produces a large volume of contaminated aqueous leachate. This study was aimed at investigating the feasibility of using electrochemical peroxidation (ECP) for the treatment of this leachate. ECP is a process by which aqueous, or suspended organic matter, is oxidised by the action of hydroxyl free radicals, produced using hydrogen peroxide and cast iron or mild steel electrodes. The effectiveness of the ECP process was quantified by measuring reductions in leachate biological oxygen demand (BOD) and chemical oxygen demand (COD) as a result of treatment. Optimisation of the process was carried out by varying electrode voltage, polarity switching rate, leachate pH and hydrogen peroxide concentration. This resulted in an observed BOD reduction of 36% and COD reduction of 52%, which was achieved by adjusting the pH to 4.0, applying an electrode voltage of 1.9V and switching speed of 5 cycles per minute. The optimum hydrogen peroxide concentration was found to be 100ppm. In addition to reductions in BOD and COD, reductions in chloride and ammonium levels were measured and found to be 15% and 18% respectively. The results of the investigation indicate that the ECP process is effective in the treatment of landfill leachate, and suggest that with further optimisation, ECP may serve as an attractive alternative to current biological leachate treatment methods.