Factors effecting aluminum speciation in drinking waterby laboratory research
Wendong Wang , Hongwei Yang , Xiaochang Wang , Jing Jiang , Wanpeng Zhu
DOI:
Received April 14, 2009,Revised May 16, 2009, Accepted , Available online
Volume 22,2010,Pages 47-55
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Effects of aluminum on water distribution system and human health mainly attribute to its speciation in drinking water. Laboratory
experiments were performed to investigate factors that may influence aluminum speciation in water supply system. The concentration
of soluble aluminum and its transformation among other aluminum species were mainly controlled by kinetics processes of related
reactions. Total aluminum concentration had a notable e ect on the concentrations of mononuclear and soluble aluminum in the first 4
day; then its e ect became weak. At pH above 7.50, both fluoride and orthophosphate had little e ect on aluminum speciation; while,
when the solution pH was below 7.50, the concentrations of mononuclear and soluble aluminum were proportional to the concentration
of fluoride and inversely proportional to the concentration of orthophosphate. Both mononuclear and polynuclear silicic acids could
complex with mononuclear aluminum by forming soluble aluminosilicates. In addition, the adding sequence of orthophosphate and
aluminum into drinking water would also a ect the distribution of aluminum species in the first 4 day. In order to minimize aluminum
bioavailability in drinking water, it was suggested that orthophosphate should be added prior to coagulant process, and that the
concentrations of fluoride and silicic acids should be controlled below 2.0 and 25 mg/L, respectively, prior to the treatment. The
solution pH in coagulation and filtration processes should be controlled in the range of 6.50–7.50.
