Advanced Treatment of Paper Mill Wastewater Using Electro-Fenton Process with Novel Catalytic Particle Electrodes

Abstract

Waste rice straw and iron-containing sludge were converted into catalytic particle electrodes (CPEs). The CPEs were tested for their ability to strengthen electro-Fenton (EF) oxidation of real paper mill wastewater. The prepared CPEs were characterized by different techniques including scanning electron microscopy, X-ray diffraction, BET surface area, and X- ray fluorescence. The CPEs exhibited excellent electro-catalytic activity and appreciably reduced the levels of pollutant parameters during EF process at near neutral pH conditions. Additionally, the treated wastewater was more biodegradable and had lower toxicity, which met Chinese effluent discharge criteria. Optimized treatment conditions used were a current density of 10 mA/cm2, a CPEs dosage of 1.0 g/L, and an aeration rate of 5 L/min. Based on the measurements of H2O2 and hydroxyl radicals (oOH), the enhancement of catalytic activity was attributed to more in situo OH being produced from the H2O2 which was generated from dissolved oxygen (DO). Moreover, the CPEs showed superior stability, and successive recycle runs were completed with efficient and economical application advantages.