Minimizing residual aluminum concentration in treated water by tailoring properties of polyaluminum coagulants

Aluminum coagulants are widely used in water treatment plants to remove turbidity and dissolved substances. However, because high aluminum concentrations in treated water are associated with increased turbidity and because aluminum exerts undeniable human health effects, its concentration should be...

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Bibliographic Details
Published in:Water research (Oxford) 2013-04, Vol.47 (6), p.2075-2084
Main Authors: Kimura, Masaoki, Matsui, Yoshihiko, Kondo, Kenta, Ishikawa, Tairyo B., Matsushita, Taku, Shirasaki, Nobutaka
Format: Article
Language:English
Subjects:
Aluminum
Aluminum - analysis
Aluminum - chemistry
Aluminum Compounds - chemistry
Aluminum Hydroxide - chemistry
Applied sciences
Basicity
Chemical Precipitation
Coagulants
Coagulation
Colloids
Dissolution
Drinking Water - chemistry
Drinking water and swimming-pool water. Desalination
Exact sciences and technology
Filtration
Flocculation
General purification processes
human health
Humic Substances - analysis
Hydrogen-Ion Concentration
Indicators and Reagents - chemistry
Japan
Molecular Weight
Monomer Al
organic matter
Osmolar Concentration
PACl
Pollution
Rivers - chemistry
Solubility
Sulfate
Temperature
Turbidity
Wastewaters
Water Pollutants, Chemical - analysis
Water Pollutants, Chemical - chemistry
Water Purification
Water Quality
Water treatment
Water treatment and pollution
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Summary:Aluminum coagulants are widely used in water treatment plants to remove turbidity and dissolved substances. However, because high aluminum concentrations in treated water are associated with increased turbidity and because aluminum exerts undeniable human health effects, its concentration should be controlled in water treatment plants, especially in plants that use aluminum coagulants. In this study, the effect of polyaluminum chloride (PACl) coagulant characteristics on dissolved residual aluminum concentrations after coagulation and filtration was investigated. The dissolved residual aluminum concentrations at a given coagulation pH differed among the PACls tested. Very-high-basicity PACl yielded low dissolved residual aluminum concentrations and higher natural organic matter (NOM) removal. The low residual aluminum concentrations were related to the low content of monomeric aluminum (Ala) in the PACl. Polymeric (Alb)/colloidal (Alc) ratio in PACl did not greatly influence residual aluminum concentration. The presence of sulfate in PACl contributed to lower residual aluminum concentration only when coagulation was performed at around pH 6.5 or lower. At a wide pH range (6.5–8.5), residual aluminum concentrations
ISSN:0043-1354
1879-2448
DOI:10.1016/j.watres.2013.01.037