title: Enhancement of activated sludge dewatering performance by combined composite enzymatic lysis and chemical re-flocculation with inorganic coagulants: Kinetics of enzymatic reaction and re-flocculation morphology.
abstract: The feasibility of combined process of composite enzymatic treatment and chemical flocculation with inorganic salt coagulants was investigated in this study. The evolution of extracellular polymeric substances (EPS) distribution, composition and morphological properties were analyzed to unravel the sludge conditioning mechanism. It was found that sludge filtration performance was deteriorated due to release of a large amount of biopolymers after enzymatic treatment. The change in EPS followed the pseudo-first-order kinetic equation well under enzymatic treatment. The feeding modes of enzymes had a significant influence on sludge lysis efficiency under compound enzymes treatment. Alpha amylase + protease was more effective in solubilization than other two addition modes (protease + α-amylase or simultaneous addition). The sludge floc re-formed and macromolecule biopolymers were effectively removed through coagulation process. At the same time, both of filtration rate and cake solid content of sludge treated with enzymes were improved with increasing dosage of coagulants, and ferric iron (FeCl3) had better performance in sludge dewaterability enhancement than polyaluminium chloride (PACl). In addition, sludge filtration property was slightly deteriorated, while the cake moisture reduction was favored at the optimal dosage of inorganic coagulants.
authors.affiliation: School of Environmental Studies, China University of Geosciences, Wuhan 430074, China; 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: School of Environmental Studies, China University of Geosciences, Wuhan 430074, China; State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China. Electronic address: zhwj_1986@126.com.
authors.forename: Weijun
authors.initials: W
authors.lastname: Zhang
authors.affiliation: School of Environmental Studies, China University of Geosciences, Wuhan 430074, China; State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, 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, China.
authors.forename: Teng
authors.initials: T
authors.lastname: Ma
authors.affiliation: School of Civil Engineering, Inner Mongolia University of Technology, Hohhot 010051, China.
authors.forename: Runying
authors.initials: R
authors.lastname: Bai
mesh_terms: D001419:Bacteria / Q000378:metabolism*; D001704:Biopolymers / Q000378:metabolism; D005374:Filtration; D005427:Flocculation; D006868:Hydrolysis; D007700:Kinetics; D012722:Sewage / Q000737:chemistry*; D012965:Sodium Chloride / Q000737:chemistry; D014865:Waste Disposal, Fluid / Q000295:instrumentation / Q000379:methods*
chemical_list: D001704:Biopolymers; D012722:Sewage; D012965:Sodium Chloride
keywords: Enzymatic treatment; Extracellular polymeric substances; Floc morphology; Inorganic salt coagulants; Sludge dewatering performance; Waste activated sludge