title: Effect of dosing sequence and solution pH on floc properties of the compound bioflocculant-aluminum sulfate dual-coagulant in kaolin-humic acid solution treatment.
abstract: The compound bioflocculant (CBF)-aluminum sulfate (AS) dual-coagulant and AS were comparatively studied for the coagulation of kaolin-humic acid solution. Floc properties including floc growth rate, size, strength, recoverability and fractal dimension under different pH conditions were investigated by Mastersizer 2000. Results indicated that, the flocs formed by AS-CBF (AS dosed first) showed the largest size and the best recoverability across the pH range investigated. While flocs formed by CBF-AS gave the most compact structure. The three coagulants exhibited similar floc growth rate and strength. Moreover, flocs formed in acidic conditions were stronger and more recoverable but showed lower growth rate, smaller size and looser structure compared to those formed at pH>6 regardless of the coagulant used. Charge neutralization was the dominant mechanism for AS at low pH, while the coagulation mechanism transformed to enmeshment as the pH increased. There was an additional adsorption bridging effect for AS-CBF and CBF-AS.
authors.affiliation: School of Environmental Science and Engineering, Shandong University, No. 27, Shanda South Road, Jinan 250100, Shandong, PR China.
authors.forename: Xiaowen
authors.initials: X
authors.lastname: Bo
authors.forename: Baoyu
authors.initials: B
authors.lastname: Gao
authors.forename: Nana
authors.initials: N
authors.lastname: Peng
authors.forename: Yan
authors.initials: Y
authors.lastname: Wang
authors.forename: Qinyan
authors.initials: Q
authors.lastname: Yue
authors.forename: Yingcan
authors.initials: Y
authors.lastname: Zhao
mesh_terms: D000534:Alum Compounds / Q000737:chemistry*; D005427:Flocculation; D017709:Fractals; D006812:Humic Substances; D006863:Hydrogen-Ion Concentration; D007616:Kaolin / Q000737:chemistry*; D010316:Particle Size; D012996:Solutions
chemical_list: D000534:Alum Compounds; D006812:Humic Substances; D012996:Solutions; D007616:Kaolin; C041524:aluminum sulfate