Coupled heat-activated persulfate - Electrolysis for the abatement of organic matter and total nitrogen from landfill leachate

This work analyzes the viability of a coupled heat-activated persulfate (PS) and electro-oxidation treatment toabatetheorganic matter and nitrogen from a high polluted landfill leachate (5500 mg L-1 TOC; 5849 mg L-1 TN, pH: 8.4). These characteristics makes PS as a suitable oxidant to deal with the recalcitrant organic matter. Under the optimal conditions (70 degrees C and 60% of the stoichiometric amount of PS), around 60% of the initial organic load was mineralized. On the contrary, the nitrogen removal was below 20%. A subsequent electrolytic stage using Ti/IrO2-TaO2 anode at 175 mA cm(-2) and 0.42 M NaCl during 60 min, led to overall organic matter and nitrogen removal above 85% and 90%, respectively, with energy requirement of 38 kWh per kg of nitrogen removed. In this sense, the combined process achieves a significant reduction in terms of energy consumption, up to one fifth in relation to sole electrolysis. These results confirm the feasibility of this combined process to treat landfill leachate. (C) 2019 Elsevier Ltd. All rights reserved.