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 effect on the concentrations of mononuclear and soluble aluminum in the first 4 day; then its effect became weak. At pH above 7.50, both fluoride and orthophosphate had little effect 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 affect 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.
结合微生物学传统培养和分子生物学现代技术,分析了无规聚丙烯(Po lypropy lene R andom,PPR)管、镀锌钢管和铜管3种室内给水管附生生物膜微生物群落。结果表明,在以上3种管道上发育1年的附生生物膜中,分别有6种、5种和3种优势异养菌被分离出来;α变形杆菌纲优势异养菌所占比例在PPR管、镀锌钢管和铜管附生生物膜中依次增加,而β变形杆菌纲和放线菌纲优势异养菌所占比例则依次减小;镀锌钢管和PPR管附生生物膜中均存在作为优势异养菌的机会病原体,而铜管附生生物膜中则未分离出作为优势异养菌的机会病原体。
