title: Improvement of wastewater sludge dewatering performance using titanium salt coagulants (TSCs) in combination with magnetic nano-particles: Significance of titanium speciation.
abstract: In this study, the effects of chemical conditioning using titanium salt coagulants (TSCs) of different hydrolysis speciation in combination with magnetic nano-particles on dewatering performance of waste activated sludge were evaluated by means of specific resistance to filtration (SRF) and capillary suction time (CST). The morphological and extracellular polymeric substances (EPS) properties under chemical conditioning were investigated in detail to understand the reaction mechanisms involved. The results showed that the TSC with basicity of 0.5 performed better in improving sludge dewatering performance than other TSCs. Sludge floc formed by TSC0.5treatment was characterized by larger floc size and higher floc strength than that conditioned by other TSCs. EPS compression and densification were the major mechanisms of sludge conditioning, and TSC0.5had better performance in compressing EPS structure. In addition, reduction of soluble EPS concentration, especially protein-like substances contributed to improvement of sludge filterability under conditioning. Furthermore, addition of Fe2O3nanoparticles could further improve dewatering performance and decrease compressibility of sludge system by acting as skeleton builders and enhancing floc strength. The sludge particles aggregation efficiency was effectively improved with addition of nano-Fe2O3. They also were able to bind with protein-like substance in EPS component, which might contribute to promotion of sludge filterability.
authors.affiliation: School of Environmental Studies, China University of Geosciences, Wuhan 430074, Hubei, China. Electronic address: zhwj_1986@126.com.
authors.forename: Weijun
authors.initials: W
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; School of Civil Engineering, Inner Mongolia University of Technology, Hohhot 010051, China.
authors.forename: Zhan
authors.initials: Z
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Bingdi
authors.initials: B
authors.lastname: Cao
authors.affiliation: State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, Hubei, China.
authors.forename: Youjing
authors.initials: Y
authors.lastname: Du
authors.affiliation: State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Caixia
authors.initials: C
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, Hubei, China. Electronic address: wgds@rcees.ac.cn.
authors.forename: Dongsheng
authors.initials: D
authors.lastname: Wang
authors.affiliation: School of Environmental Studies, China University of Geosciences, Wuhan 430074, Hubei, China. Electronic address: mateng@cug.edu.cn.
authors.forename: Teng
authors.initials: T
authors.lastname: Ma
authors.affiliation: Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, Hubei, China.
authors.forename: Hua
authors.initials: H
authors.lastname: Xia
mesh_terms: D005290:Ferric Compounds; D005374:Filtration; D012722:Sewage / Q000737:chemistry*; D014025:Titanium; D014865:Waste Disposal, Fluid; D062065:Wastewater; D014867:Water / Q000737:chemistry
chemical_list: D005290:Ferric Compounds; D012722:Sewage; D014025:Titanium; D062065:Wastewater; D014867:Water
keywords: Combined conditioning; Dewaterability; EPS; Titanium salt coagulants; Titanium speciation; Wastewater sludge