Sanitary landfill leachate treatment by aerated electrochemical Fenton process

Abstract

The aerated electrochemical Fenton procedure was investigated as a viable treatment approach for electrolytic degradation and decolourization of sanitary landfill leachate. The optimization effects of initial pH, applied voltage, H₂O₂ concentration and combination of iron electrodes on detoxification were demonstrated by COD and colour removal from stabilized leachate, respectively. The study illustrates that, under the optimum experimental parameters voltage of 4.5 V, electrolysis time of 90 min, H₂O₂ dosage of 5 g/L, pH 3, 99% of chemical oxygen demand (COD) and 100% colour are removed from stabilized leachate, and the biodegradability ratio of the five-day biochemical oxygen demand (BOD₅) to COD increases from 0.1 to 0.72. In addition, the pure catalytic metallic iron anode and cathode electrode used in the electrochemical Fenton process was first electro-oxidized to Fe²⁺ for use during the Fenton reaction, then with Fe³⁺ that was reverted back to Fe²⁺ under the applied electrochemical-magnetic field, resulting in the iron dissolution and regeneration circuit (Fe²⁺/Fe³⁺/Fe²⁺). Additionally, Fe²⁺/Fe³⁺ served as bridges for agglomerates to coalesce into big, closely packed particles for better filterability and sedimentation action. As a preparatory step for the biochemical treatment, this technology has been effectively used to treat stabilized landfill leachate containing toxic refractory recalcitrant organics on a large scale. Additionally, by estimating the scientific experiment with a regression model approach for the outcomes, RSM software was employed in order to standardize the ECF treatment process, significantly reducing the number of test cases and trials.

Keywords: Aerated electrochemical fenton; Decolourization; Degradation; RSM optimization; Sacrificial iron electrodes; Stabilized leachate.