title: Characterization of size, strength and structure of aluminum-polymer dual-coagulant flocs under different pH and hydraulic conditions.
abstract: The objectives of this study are to investigate the impact of papermaking sludge product (LA) on coagulation performance and floc properties under different solution pH and hydraulic conditions. LA was synthetized by grafting acrylamide onto the lignin that contained in papermaking sludge. Characterization of LA, such as FTIR, SEM, zeta potential and molecular weight, showed that target product was obtained successfully. LA was used in combination with aluminum sulfate or polyaluminum chloride, namely Al-LA (Al was dosed firstly) and LA-Al (LA was dosed firstly), in humic acid water treatment. Floc properties and coagulation behaviors of aluminum salts and the dual-coagulants were comparatively evaluated. Results showed that DOC removal was improved by LA at pH 4 ~ 9 and the removal variations caused by different pH were decreased. Flocs formed at pH 5 and pH 8 gave quite large floc size. Floc recoverability declined as initial pH increased. Floc size, growth rate and recoverability were in the order of Al-LA>LA-Al>Al. Furthermore, flocs formed at pH 7 showed the weakest resistance to increasing shear force. Fractal dimension was rather high at pH 7 and 8 and it was in the following order: Al>LA-Al>Al-LA.
authors.affiliation: Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, No 27 Shanda South Road, Jinan 250100, Shandong, People's Republic of China.
authors.forename: Hongyan
authors.initials: H
authors.lastname: Rong
authors.forename: Baoyu
authors.initials: B
authors.lastname: Gao
authors.forename: Min
authors.initials: M
authors.lastname: Dong
authors.forename: Yanxia
authors.initials: Y
authors.lastname: Zhao
authors.forename: Shenglei
authors.initials: S
authors.lastname: Sun
authors.lastname: Yanwang
authors.forename: Qinyan
authors.initials: Q
authors.lastname: Yue
authors.forename: Qian
authors.initials: Q
authors.lastname: Li
mesh_terms: D020106:Acrylamide / Q000737:chemistry*; D000534:Alum Compounds / Q000737:chemistry*; D000536:Aluminum Hydroxide / Q000737:chemistry*; D005427:Flocculation; D006812:Humic Substances; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste; D008031:Lignin / Q000737:chemistry*; D010209:Paper; D010316:Particle Size
chemical_list: D000534:Alum Compounds; D006812:Humic Substances; D007220:Industrial Waste; C016213:aluminum oxychloride; D020106:Acrylamide; C041524:aluminum sulfate; D000536:Aluminum Hydroxide; D008031:Lignin