The use of polyaluminium chloride as a restoration measure to improve water quality in tropical shallow lakes

Abstract Aim The aim of this study was to evaluate the performance of the coagulant Polyaluminium chloride (PAC) in water quality improvement of six eutrophic shallow lakes in Brazilian semiarid region. Methods We evaluated the effect of PAC in turbidity, humic substances (UV254), total phosphorus and chlorophyll-a concentration through laboratory jar tests. Results The results showed that PAC had a good performance in reducing total phosphorus concentrations and turbidity, with a reduced efficiency in removing chlorophyll-a and humic substances by sedimentation of flocks formed. Conclusions Addition of PAC is a potential tool for water quality improvement of eutrophic shallow lakes in Brazilian semiarid region but its efficiency depends on the pH and particulate and dissolved organic matter concentration in the lake or reservoir water.

摘要
1. 研究目的：本研究旨在评估混凝剂聚合氯化铝（Polyaluminium chloride, PAC）对巴西半干旱地区6座富营养化浅水湖泊的水质改善效果。
2. 研究方法：通过实验室杯罐试验，探究PAC对浊度、腐殖物质（UV254）、总磷及叶绿素-a浓度的影响。
3. 研究结果：结果表明，PAC在降低总磷浓度与浊度方面表现优异，但通过形成絮体沉降去除叶绿素-a与腐殖物质的效率较为有限。
4. 研究结论：投加PAC是巴西半干旱地区富营养化浅水湖泊水质改善的潜在可行手段，但其处理效率取决于湖泊或水库水体的pH值、颗粒物与溶解性有机质浓度。