Effect of second coagulant addition on coagulation efficiency, floc properties and residual Al for humic acid treatment by Al₁₃ polymer and polyaluminum chloride (PACl)

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• 作者：Weiying Xu^a ; Baoyu Gao^a ; ^{baoyugao_sdu@yahoo.com.cn} ; Yan Wang^a ; Qinyan Yue^a ; Haijing Ren^b
• 关键词：Al13 ; Second dose ; Floc re-growth ; Fractal dimension ; Residual Al
• 刊名：Journal of Hazardous Materials
• 出版年：2012
• 期刊代码：50_03043894
• 类别：ce
• 出版时间：15 May, 2012
• 卷：215-216
• 期：Complete
• 页码：129-137
• 文件大小：752 K

摘要

Influence of second dose on coagulation efficiency, floc re-growth, fractal structure and residual Al of the effluent in humic acid (HA) coagulation with Al₁₃ polymer ([Al₁₃O₄(OH)₂₄(H₂O)₁₂]⁷⁺) and PACl were comparatively investigated in this study. Effects of breakage shear on the floc properties generated in the coagulation with and without additional dose were also investigated. The results indicated that additional dose during breakage could essentially improve the HA removal efficiency and floc re-growth in both Al₁₃ and PACl coagulations. Second doses of Al₁₃ at 0.5 and 1.0 mg/L resulted in better turbidity and UV₂₅₄ removal as well as floc re-growth rather than higher additional dose of 1.5 and 2.0 mg/L; while in PACl coagulation, more efficient HA removal and better floc re-growth were obtained at higher additional doses (1.0, 1.5 and 2.0 mg/L). Small additional Al₁₃ could apparently increase the D_f of re-formed flocs while the additional PACl displayed inconspicuous effect on floc D_f. The additional coagulant dose could alleviate the further decrease of re-grown floc size with increased breakage shear for both coagulants. The residual Al analysis implied that two-stage addition contributed to lower residual Al in effluent than one-time addition mode with the same total coagulant concentration.