Aluminum fractions in drinking water from reservoirs

To provide insight into aluminum speciation in ram and in finished water an d to investigate the factors that can affect it, specific aluminum fraction s have been isolated and analyzed in water samples from three drinking wate r reservoirs in Sardinia (Italy) and at the outlet of their treatment plant s. All water treatment plants employed polyaluminum chloride as coagulant. The results demonstrate that the treatment of raw water with the aluminum-b ased coagulant did not increase the concentration of the metal in the finis hed water. Aluminum fractions were quite different in raw mater and in fini shed water. More than 80% of the aluminum in raw water was in the particula te form. In the dissolved fraction, organic forms were present at higher co ncentrations in the raw water, while following water treatment (coagulation , flocculation, filtration) most of the aluminum was in the inorganic form. Most of the dissolved Al in raw water was strongly bound or polymeric coll oidal, while percentages of monomeric Al ranging from 40 to 62% were presen t in the finished water. (C) 2000 Academic Press.