title: The transformation of aluminium species in the processes of coagulation, sedimentation and filtration.
abstract: The aluminium toxicity is closely related to aluminium species. In this work aluminium was fractionated into seven forms: Al(T), Al(Sus), Al(C + S), Al(S), Al(C), Al(O) and Al(I). Four Al-based coagulants and simulated raw water were used in the laboratory to investigate the aluminium transformation in coagulation, sedimentation and filtration processes. It is the use of Al-based coagulants that contributes more to the increase of the residual aluminium for the low-turbidity raw water, while the Al-based coagulants, especially the polymeric aluminium coagulants, work to remove the aluminium from the high-turbidity raw water. In the case of traditional coagulants, the increase of the turbidity or the dissolved organic carbon (DOC) concentration in the raw water results in a high concentration of Al(C + S). The removal rate of aluminium species in the filtration process is not only related to its size: RAl(Sus) > RAl(C+S), RAl(C) > RAl(S), but also to the physicochemical properties of aluminium species and filter. For the kaolin-polyaluminium chloride system, a lower removal rate of aluminium species results is due to the complexation of humic acid and aluminium species.
authors.affiliation: Department of Environmental Science and Engineering, Tsinghua University, Beijing, China. zhaohuazhang@iee.pku.edu.cn
authors.forename: H Z
authors.initials: HZ
authors.lastname: Zhao
authors.forename: H W
authors.initials: HW
authors.lastname: Yang
authors.forename: Y T
authors.initials: YT
authors.lastname: Guan
authors.forename: Z P
authors.initials: ZP
authors.lastname: Jiang
mesh_terms: D000535:Aluminum / Q000737:chemistry*; D017607:Aluminum Compounds / Q000737:chemistry*; D005374:Filtration / Q000379:methods*; D018508:Water Purification / Q000379:methods*
chemical_list: D017607:Aluminum Compounds; D000535:Aluminum