In situ generation of zero valent iron for enhanced hydroxyl radical oxidation in an electrooxidation system for sewage sludge dewatering

TY - JOUR

T1 - In situ generation of zero valent iron for enhanced hydroxyl radical oxidation in an electrooxidation system for sewage sludge dewatering

AU - Hu, Shaogang

AU - Hu, Jingping

AU - Liu, Bingchuan

AU - Wang, Dongliang

AU - Wu, Longsheng

AU - Xiao, Keke

AU - Liang, Sha

AU - Hou, Huijie

AU - Yang, Jiakuan

N1 - Publisher Copyright: © 2018 Elsevier Ltd

PY - 2018/11/15

Y1 - 2018/11/15

N2 - A hybrid electrochemical conditioning strategy for enhanced sewage sludge dewatering was proposed. A water content of 47.2 wt.% for the dewatered sludge cake was achieved at an applied voltage of 20 V for 30 min, which was significantly lower than previously reported results. The capillary suction time (CST) and specific resistance to filtration (SRF) were decreased by 75.6% and 90.9%, respectively. Four simultaneous processes, including electrooxidation, the electro-Fenton process, molecular oxygen activation via zero valent iron (ZVI) and Fe(III) flocculation, had synergetic effects on the degradation of extracellular polymeric substances (EPS) to enhance sludge dewaterability. The in situ generation of ZVI on the cathode electrode facilitated the reduction of Fe(III) to Fe(II) via activation of molecular oxygen. The sludge pH decreased spontaneously and remained acidic due to the competitive reaction of ZVI generation to hydrogen evolution as well as the Fe(III) flocculation process, which further guaranteed the high efficiency of hydroxyl radical generation. Changes in the physiochemical properties of the sludge (particle size distribution, zeta potential, viscosity and EPS characteristics) induced by the hybrid conditioning process were further explored. In addition, the economic potential of the hybrid system was preliminarily assessed (USD$ 127.6/ton dry sludge).

AB - A hybrid electrochemical conditioning strategy for enhanced sewage sludge dewatering was proposed. A water content of 47.2 wt.% for the dewatered sludge cake was achieved at an applied voltage of 20 V for 30 min, which was significantly lower than previously reported results. The capillary suction time (CST) and specific resistance to filtration (SRF) were decreased by 75.6% and 90.9%, respectively. Four simultaneous processes, including electrooxidation, the electro-Fenton process, molecular oxygen activation via zero valent iron (ZVI) and Fe(III) flocculation, had synergetic effects on the degradation of extracellular polymeric substances (EPS) to enhance sludge dewaterability. The in situ generation of ZVI on the cathode electrode facilitated the reduction of Fe(III) to Fe(II) via activation of molecular oxygen. The sludge pH decreased spontaneously and remained acidic due to the competitive reaction of ZVI generation to hydrogen evolution as well as the Fe(III) flocculation process, which further guaranteed the high efficiency of hydroxyl radical generation. Changes in the physiochemical properties of the sludge (particle size distribution, zeta potential, viscosity and EPS characteristics) induced by the hybrid conditioning process were further explored. In addition, the economic potential of the hybrid system was preliminarily assessed (USD$ 127.6/ton dry sludge).

KW - Electro-Fenton

KW - Electrolysis

KW - Electrooxidation

KW - Molecular oxygen activation

KW - Sewage sludge dewatering

KW - Zero valent iron

UR - http://www.scopus.com/inward/record.url?scp=85051799916&partnerID=8YFLogxK

U2 - 10.1016/j.watres.2018.08.027

DO - 10.1016/j.watres.2018.08.027

M3 - 文章

C2 - 30142514

AN - SCOPUS:85051799916

SN - 0043-1354

VL - 145

SP - 162

EP - 171

JO - Water Research

JF - Water Research

ER -