Effects of piecewise electric field operation on sludge dewatering

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Effects of piecewise electric field operation on sludge dewatering: phenomena and mathematical model Hang Lv, Fang Wang, Daoguang Liu, Yanlin Zhang, Yueyuan Gu, Du Yuan, Siqi Xing, Xu Wu, Jiakuan Yang, Wenbiao Zhang, and Keith Scott Ind. Eng. Chem. Res., Just Accepted Manuscript • Publication Date (Web): 04 Jun 2018 Downloaded from http://pubs.acs.org on June 4, 2018

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Industrial & Engineering Chemistry Research

Effects of piecewise electric field operation on sludge dewatering: phenomena and mathematical model Hang Lv1#, Fang Wang1#, Daoguang Liu2, Yanlin Zhang1, Yueyuan Gu1, Du Yuan1, Siqi Xing1, Xu Wu1,*, Jiakuan Yang1, Wenbiao Zhang2, Keith Scott3 1, School of Environmental Science and Engineering, Huazhong Unviersity of Science and Technology, 1037 Luoyu Road, Wuhan, 430074, China 2, Shanghai Techase Environment Protection Co., Ltd. 1121 North Zhongshan No. 2 Road, Shanghai, 200092, China 3, School of Chemical Engineering and Advanced Materials, Newcastle University, Newcastle upon Tyne, NE1 7RU, United Kingdom Abstract: Electro-dewatering (EDW) is an energy-efficient method for sludge dewatering. In this study, effects of piecewise electric field operation on EDW were investigated by experiments and simulation. Operational parameters were studied mainly in terms of sludge resistance variation during electro-dewatering process, which were evaluated by linear sweep voltammetry (LSV) analysis. Simulation of the sludge cake electro-dewatering processes was developed and validated, based upon time-dependent experimental data of electric currents and filtrate weights. The modeling results were in good agreement with experiments. It was proved by experimental and modelling results that the piecewise operation has positive effects on key performances of EDW devices, i.e. limited water content, space-time yield, and mass specific energy consumption. Keywords: Sewage Sludge, Electro-dewatering, Model Simulation, Piecewise Electric Field strength.

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1. INTRODUCTION Over the last decades, municipal and industrial wastewater purification activities have been increasing, which confronts with a dramatically increasing flow of sewage sludge 1, 2. Sewage sludge usually contain high water contents, gelatinous structures of hydrophilic substances, organic pollutants, pathogens, heavy metals and other toxic and hazardous substances, making them rather ill-defined systems with difficulties in solid-liquid separation. If not properly disposed, sewage sludge will lead to serious secondary environmental pollution 3. Sludge dewatering is an important process in the sludge treatment project and such projects in many areas often account for approximately 50% of all costs in wastewater treatment 3. Currently in China, sewage sludge with moisture content higher than 60 wt. % is not allowed for further disposal, for example after traditional mechanical solid-liquid separation 4. EDW is a highly efficient technique for sludge deep dewatering, which may reduce the water content of sludge cakes to