Enhanced Sludge Dewatering by Fenton-Like Reaction Initiated by Fe-Rich Sludge Biochar with In-Situ Generation of H2o2: Fe/C Structure as an Electron Shuttle

Abstract

Fenton-like reaction has been used to enhance sludge dewaterability effectively. However, H2O2 has dangerous characteristics of being explosive and unstable. In this study, a new process of in-situ H2O2 generation by Fe-rich sludge biochar under aeration condition combined with poly-diallyldimethylammonium chloride (PDMDAAC) was proposed for enhancing sludge dewaterability. Under the optimized conditions, the capillary suction time and specific resistance to filterability of the conditioned sludge were reduced significantly compared with raw sludge (54.2 vs. 351 s, 0.249×1013 vs. 2.68×1013 m/kg, respectively). The carbon skeleton in Fe-rich sludge biochar can reduce the charge transfer impedance of the electron transfer between Fe and O2, promoting the in-site generation of H2O2. The degradation of hydrophilic organics in extracellular polymeric substances of sludge floc and the PDMDAAC coagulation effect caused release of bound water. This study provides a strategy to enhanced sludge dewaterability by Fenton-like reaction initiated by Fe-rich biochar with no H2O2 addition.

Keywords: Fe-rich sludge biochar, Sludge dewaterability, In-situ generation of H2O2, Electron shuttle, Extracellular polymeric substances