Electrochemical oxidation of landfill leachates at pilot scale: evaluation of energy needs

Two of the main drawbacks to be overcome before full scale implementation of boron-doped diamond electro-oxidation were addressed in this work; its energy consumption and hazard of formation of chlorinated organics. This was framed within a study in which the technical and economic feasibility of BDD electro-oxidation of landfill leachate was evaluated at pilot scale. On one hand, its technical feasibility was assessed based on COD and NH₄⁺ removal, allowing the selection of the operation conditions that provide optimal energy efficiency, and special attention was paid to the risk of formation of undesired by-products such as nitrite, nitrate ions and trihalomethanes. On the other hand, treatment costs were estimated based on energy consumption required to reach the disposal limits to natural watercourses established by legislation. The results were compared with those of other commonly used AOPs. Under the operating conditions studied, the concentration of COD decreased below the disposal limit (160 mg L⁻¹) and ammonia concentration reached values as low as 30 mg L⁻¹. The energy consumption needed was estimated at 54 kWh/m³ and the formation of chlorination by-products appeared to be low as the maximum total trihalomethane concentration detected was 432 μg/L.