Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
J Environ Sci (China). 2016 Apr;42:142-151. doi: 10.1016/j.jes.2015.05.010. Epub 2015 Jul 6.
Finished drinking water usually contains some residual aluminum. The deposition of residual aluminum in distribution systems and potential release back to the drinking water could significantly influence the water quality at consumer taps. A preliminary analysis of aluminum content in cast iron pipe corrosion scales and loose deposits demonstrated that aluminum deposition on distribution pipe surfaces could be excessive for water treated by aluminum coagulants including polyaluminum chloride (PACl). In this work, the deposition features of different aluminum species in PACl were investigated by simulated coil-pipe test, batch reactor test and quartz crystal microbalance with dissipation monitoring. The deposition amount of non-polymeric aluminum species was the least, and its deposition layer was soft and hydrated, which indicated the possible formation of amorphous Al(OH)3. Al13 had the highest deposition tendency, and the deposition layer was rigid and much less hydrated, which indicated that the deposited aluminum might possess regular structure and self-aggregation of Al13 could be the main deposition mechanism. While for Al30, its deposition was relatively slower and deposited aluminum amount was relatively less compared with Al13. However, the total deposited mass of Al30 was much higher than that of Al13, which was attributed to the deposition of particulate aluminum matters with much higher hydration state. Compared with stationary condition, stirring could significantly enhance the deposition process, while the effect of pH on deposition was relatively weak in the near neutral range of 6.7 to 8.7.
饮用水通常含有一些残留的铝。残留铝在分配系统中的沉积和潜在的释放回饮用水中，可能会显著影响消费者龙头处的水质。对铸铁管腐蚀垢和松散沉积物中铝含量的初步分析表明，对于用铝混凝剂（包括聚合氯化铝 (PACl)）处理的水，铝在分配管表面的沉积量可能过高。在这项工作中，通过模拟盘管测试、批量反应器测试和石英晶体微天平与耗散监测研究了 PACl 中不同铝物种的沉积特征。非聚合铝物种的沉积量最少，其沉积层柔软且水合，表明可能形成无定形 Al(OH)3。Al13 的沉积趋势最高，沉积层坚硬且水合程度较低，表明沉积的铝可能具有规则的结构，Al13 的自聚集可能是主要的沉积机制。而对于 Al30，与 Al13 相比，其沉积速度相对较慢，沉积的铝量也相对较少。然而，Al30 的总沉积质量远高于 Al13，这归因于具有更高水合状态的颗粒状铝物质的沉积。与静态条件相比，搅拌可以显著增强沉积过程，而在 6.7 到 8.7 的近中性范围内，pH 值对沉积的影响相对较弱。
