title: Floc properties of polyaluminum ferric chloride in water treatment: The effect of Al/Fe molar ratio and basicity.
abstract: Producing flocs with desired properties is significant for contaminants removal in water treatment works. In this study, an inorganic composite coagulant, polyaluminum ferric chloride (PAFC), was prepared and used in surface water treatment, and the influence of Al/Fe molar ratio and basicity (B) on floc properties was investigated. The contribution of metal species analysis showed a competition relationship between Al and Fe in the pre-hydrolysis, while the monomeric contents decreased with the increase of B value. The investigation of floc properties was conducted on a laser scattering instrument, in terms of floc size, strength, recovery capacity and fractal dimension (Df). The largest floc size and the highest growth rate was achieved when Al/Fe=7:1 and B=1.5. Floc formed at the Al/Fe ratios of 5:1 and 7:1 were considered to be more compact. Meanwhile, the Df value increased when B value was increased. At Al/Fe=7:1 and B=1.5, strongest flocs were obtained. During the breakage period, the Df value increased. As lower shear was replaced, the floc size decreased continuously, with a further increase of Df value. However, after breakage at higher shear, all of the PAFC flocs showed capacity for regrowth and loose structures were formed.
authors.affiliation: Department of Municipal & Environmental Engineering, School of Civil Engineering, Beijing Jiaotong University, Beijing 100044, PR China. Electronic address: baichuancao@gmail.com.
authors.forename: Baichuan
authors.initials: B
authors.lastname: Cao
authors.affiliation: School of Environmental Science and Engineering, Shandong University, Jinan 250100, PR China.
authors.forename: Baoyu
authors.initials: B
authors.lastname: Gao
authors.affiliation: School of Environmental, Tsinghua University, Beijing 100084, PR China.
authors.forename: Mengmeng
authors.initials: M
authors.lastname: Wang
authors.affiliation: Shandong Sanrun Environmental Protection Science Co. Ltd, Jinan 250100, PR China.
authors.forename: Xiaomei
authors.initials: X
authors.lastname: Sun
authors.affiliation: Department of Municipal & Environmental Engineering, School of Civil Engineering, Beijing Jiaotong University, Beijing 100044, PR China.
authors.forename: Jin
authors.initials: J
authors.lastname: Wang
keywords: Al/Fe molar ratio; Basicity; Floc properties; Fractal dimension; Polyaluminum ferric chloride