title: Removal of Microcystis aeruginosa using nano-Fe3O4 particles as a coagulant aid.
abstract: Blue-green algae bloom is of great concern globally since they adversely affect the water ecosystem and also drinking water treatment processes. This work investigated the removal of Microcystis aeruginosa (M. aeruginosa) by combining the conventional coagulant polyaluminum chloride (PACl) with nano-Fe3O4 particles as a coagulant aid. The results showed that the addition of nano-Fe3O4 significantly improved the removal efficiency of M. aeruginosa by reducing the amount of PACl dosage and simultaneously hastening the sedimentation. At the M. aeruginosa density of an order of magnitude of 10(7), 10(6), and 10(5) pcs/mL, respectively, the corresponding PACl dose of 200, 20, and 2 mg/L and the mass ratio of PACl to nano-Fe3O4 of 4:1, the removal efficiency of M. aeruginosa could be increased by 33.0, 44.7, and 173.1%, respectively. Compared to PACl, PACl combined with the nano-Fe3O4 as a coagulant aid had higher removal efficiency at a wider pH range. SEM images showed that nano-Fe3O4 first combined with PACl to form clusters and further generated the flocs with algae. Results from the laser particle analyzer further suggested that the floc size increased with the addition of nano-Fe3O4. It was noted that the addition of nano-Fe3O4 led to aluminum species change after PACl hydrolyzed in the algae solution, from Ala to Alb and Alc subsequently. As a coagulant aid, the nano-Fe3O4, in conjunction with PACl, apparently provided nucleation sites for larger flocs to integrate with M. aeruginosa. In addition, increased floc density improved the removal of M. aeruginosa.
authors.affiliation: School of Environmental Science and Engineering, Shanghai Jiao Tong University, No. 800 Dongchuan Road, Minhang District, Shanghai, 200240, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Zhang
authors.affiliation: School of Environmental Science and Engineering, Shanghai Jiao Tong University, No. 800 Dongchuan Road, Minhang District, Shanghai, 200240, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Jiang
authors.affiliation: School of Environmental Science and Engineering, Shanghai Jiao Tong University, No. 800 Dongchuan Road, Minhang District, Shanghai, 200240, China.
authors.forename: Xiaochen
authors.initials: X
authors.lastname: Guo
authors.affiliation: School of Environmental Science and Engineering, Shanghai Jiao Tong University, No. 800 Dongchuan Road, Minhang District, Shanghai, 200240, China. ylhe@sjtu.edu.cn.
authors.forename: Yiliang
authors.initials: Y
authors.lastname: He
authors.affiliation: NUS Environmental Research Institute, National University of Singapore, Singapore, Singapore.
authors.forename: Choon Nam
authors.initials: CN
authors.lastname: Ong
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090, China. xuyongpeng@hit.edu.cn.
authors.forename: Yongpeng
authors.initials: Y
authors.lastname: Xu
authors.affiliation: NUS Environmental Research Institute, National University of Singapore, Singapore, Singapore.
authors.forename: Amrita
authors.initials: A
authors.lastname: Pal
mesh_terms: D000535:Aluminum / Q000737:chemistry; D000536:Aluminum Hydroxide / Q000737:chemistry*; D005427:Flocculation; D006868:Hydrolysis; D058185:Magnetite Nanoparticles / Q000737:chemistry*; D046931:Microcystis / Q000737:chemistry*; D014873:Water Pollutants / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
chemical_list: D058185:Magnetite Nanoparticles; D014873:Water Pollutants; C016213:aluminum oxychloride; D000536:Aluminum Hydroxide; D000535:Aluminum
keywords: Coagulation; M. aeruginosa; Nano-Fe3O4; Polyaluminum chloride