RESUMO
To understand the water quality problems caused by deposition and re-dissolution behaviors of residual aluminum in drinking water distribution system (DWDS), the effect of polysilicic acid on the deposition and re-dissolution behaviors of different aluminum species was investigated by using jar tests and quartz crystal microbalance, which could demonstrate the deposition behavior of different aluminum species and the physic-chemical properties of deposited layers. The results showed that the effect of polysilicic acid on the deposition behavior of different aluminum species was significant. Al0 (mainly monomeric species), Al13 and Al30 (polymeric species) could react rapidly with polysilicic acid, and some insoluble products formed. However, the stability of insoluble products from different aluminum species was distinct. The insoluble product formed by reaction of Al0 with polysilicic was relatively stable. With regard to the systems of polysilicic acid with Al13 and Al30, the dissolved aluminum concentration increased with reaction time, which indicated that the deposited product could be gradually transformed to soluble monomeric or oligomeric aluminum species. Compared with the influence of Al/Si ratio on Al0, the ratio of aluminum to silicon significantly affected the deposition and re-dissolution behavior of Al13 and Al30, and the re-dissolution rate of insoluble aluminum was the most rapid when the ratio of aluminum with silica was 0.2:20 (as mass ratio of Al to SiO2).