DOI: 10.1016/j.watres.2019.02.053
Scopus记录号: 2-s2.0-85062270438
论文题名: The variation of flocs activity during floc breakage and aging, adsorbing phosphate, humic acid and clay particles
作者: Wu M. ; Yu W. ; Qu J. ; Gregory J.
刊名: Water Research
ISSN: 431354
出版年: 2019
卷: 155 起始页码: 131
结束页码: 141
语种: 英语
英文关键词: Active bonds
; Coagulation
; Floc breakage
; Humic acid
; Kaolin
; Phosphate
英文摘要: The mechanism of removal of humic acid, phosphate and kaolin particles by coagulation with alum and PACl or adsorption by their pre-formed precipitates was investigated, and it was found that the coagulation mechanisms for monomeric Al at neutral pH and polymeric Al 13 at alkaline pH were very similar. The removal of phosphate and humic acid by coagulation with alum or PACl did not change with stirring time (between 1 min and 15 min), independent of the dose and species of coagulants. However, for adsorption of these impurities by pre-formed precipitates, the results were significantly different. Both Al 3+ and nano-sized Al 13 could precipitate and form aggregates at pH 7 and pH 9, respectively, and their precipitates became less active (fewer binding sites on the surface of precipitate) with the increase of shear time or shear rates before adsorbing pollutants. Thus, although the total surface area increased (the average size of flocs became smaller) at higher applied shear rates or longer shear time, the removal efficiency of humic acid and phosphate decreased. Also, from the MW distributions, it was confirmed that less humic acid was removed by the adsorption on alum precipitate pre-formed with longer shear time. Chemical groups (OH 2 and OH) on the surface of precipitate determined the removal efficiency of phosphate and humic acid, and the activity of precipitate become lower as a result of higher applied shear and longer shear time. This is confirmed be due to some crystallization of the amorphous precipitate, forming inactivated hydroxyl. When kaolin was added 10 min after the alum or PACl precipitate formed, the precipitates captured kaolin particles only on their surface, whereas when alum was added to kaolin suspensions particles were trapped within the growing flocs. When alum/kaolin flocs were broken at high shear rate re-growth of flocs decreased with increasing shear time, but after a short breakage period, long aging of broken flocs had little effect on floc regrowth. © 2019 Elsevier Ltd Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/121912
Appears in Collections: 气候变化事实与影响
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作者单位: Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100086, China; Department of Civil, Environmental and Geomatic Engineering, University College London, Gower Street, London, WC1E 6BT, United Kingdom; Department of Civil and Environmental Engineering, Imperial College London, South Kensington Campus, London, SW7 2AZ, United Kingdom
Recommended Citation:
Wu M.,Yu W.,Qu J.,et al. The variation of flocs activity during floc breakage and aging, adsorbing phosphate, humic acid and clay particles[J]. Water Research,2019-01-01,155