Sustainable Strategy for Enhancing Anaerobic Digestion of Waste Activated Sludge: Driving Dissimilatory Iron Reduction with Fenton Sludge

Abstract

Fenton process has been extensively applied for treatment of refractory organic pollutants. While the potentially hazardous iron-containing sludge generated from the Fenton process requires proper treatment and disposal, due to its high Fe contents and toxic organic matters involved. Considering that Fe(III) oxides exhibits an ideal potential for enhancing anaerobic digestion (AD), in this study Fenton sludge with a high-abundance of Fe(III) was introduced in AD of wasted activated sludge (WAS) with the aims to improve the sludge digestion as well as to remove the organic matters in Fenton sludge. Results showed that methane production and sludge reduction of WAS were significantly improved, and the organic matters contained in Fenton sludge was removed by 70.0%. Meanwhile, nearly a half of in Fenton sludge was converted to Fe2+ via dissimilatory iron reduction during the digestion, in agreement with microbial community analysis. The study suggests a Fe recycling between AD and Fenton process that Fenton ...