Electrochemical treatment of leachate containing highly concentrated phenol and ammonia using a Pt/Ti anode at different current densities

The electrochemical oxidation of phenol in leachate was evaluated at current densities of 50, 100, and 150 mA/cm² using a Pt/Ti anode electrode in a single-chambered reactor. The feasibility of electrochemical treatment for leachate containing phenol was determined in terms of phenol, chemical oxygen demand (COD), ammonia degradation rate, gas generation, energy consumption, and current efficiency. Phenol was removed within the first-hour of treatment in all study conditions. Galvanostatic electrolysis at a current density of 150 mA/cm² removed COD and ammonia faster than the other conditions, possibly due to the formation of chloride-oxychloride radicals, which are strong oxidizing agents. The COD removal rate at 150 mA/cm² was 1.73 h⁻¹, which is 2.5–5 times higher than the values (0.35 h⁻¹) at 50 and (0.68 h⁻¹) at 100 mA/cm². For ammonia removal, the electrochemical process at 150 mA/cm² achieved a maximum removal rate of 438.6 M/h, which is at least two times higher than at the other current densities. Gas analysis during the electrolysis indicates that H₂ is generated as a valuable product of the reaction. This study reveals that electrochemical oxidation using the Pt/Ti electrode is promising for the treatment of landfill effluents containing toxic and low biodegradable contaminants and for efficient nutrient removal.