Aluminium Drinking Water Treatment Residuals and Their Toxic Impact on Human Health

Aluminium exerts undeniable human health effects, so its concentration should be controlled in water treatment plants. The article presents and discusses the results of studies on the influence of selected properties of aluminium coagulants on the concentration of aluminium remaining in the purified water. The coagulants used were classical hydrolysing aluminium salts: aluminium sulphate (VI) and sodium aluminate as well as pre-hydrolysed polyaluminium chlorides: Flokor 105B and PAX XL10 that had different the alkalinity coefficient r = [OH-]/[Al3+]. The Al species distribution in the coagulants samples were analysed by the Ferron complexation timed spectrophotometry. On the basis of their reaction rates with ferron reagent, the aluminium species were divided into three categories: monomeric (Al-a), medium polymerised (Al-b) and colloidal (Al-c). The usefulness of the tested aluminium coagulants due to the concentration of residual aluminium and dissolved aluminium, which is easily assimilated by the human body, was increased according to the following series: sodium aluminate (Al-a = 100%, Al-b = 0) < aluminium sulphate (VI) (Al-a = 91%, Al-b = 9%) < PAX XL 10 (Al-a = 6%, Al-b = 28%, r = 2.10) < Flokor 105B (Al-a = 3%, Al-b = 54%, r = 2.55).