Aquatic Ecology & Water Quality Management Group, Department of Environmental Sciences, Wageningen University, P.O. Box 47, 6700 AA, Wageningen, The Netherlands; Department of Aquatic Ecology, Netherlands Institute of Ecology (NIOO-KNAW), P.O. Box 50, 6700 AB, Wageningen, The Netherlands.
Laboratory of Ecology and Physiology of Phytoplankton, Department of Plant Biology, University of Rio de Janeiro State, Rua São Francisco Xavier 524-PHLC Sala 511a, 20550-900, Rio de Janeiro, Brazil.
Harmful Algae. 2017 Jun;66:1-12. doi: 10.1016/j.hal.2017.04.011. Epub 2017 May 5.
Removal of cyanobacteria from the water column using a coagulant and a ballast compound is a promising technique to mitigate nuisance. As coagulant the organic, biodegradable polymer chitosan has been promoted. Results in this study show that elevated pH, as may be common during cyanobacterial blooms, as well as high alkalinity may hamper the coagulation of chitosan and thus impair its ability to effectively remove positively buoyant cyanobacteria from the water column. The underlying mechanism is likely a shielding of the protonated groups by anions. Inasmuch as there are many chitosan formulations, thorough testing of each chitosan prior to its application is essential. Results obtained in glass tubes were similar to those from standard jar tests demonstrating that glass tube tests can be used for testing effects of coagulants and ballasts in cyanobacteria removal whilst allowing far more replicates. There was no relation between zeta potential and precipitated cyanobacteria. Given the well-known antibacterial activity of chitosan and recent findings of anti-cyanobacterial effects, pre-application tests are needed to decipher if chitosan may cause cell leakage of cyanotoxins. Efficiency- and side-effect testing are crucial for water managers to determine if the selected approach can be used in tailor-made interventions to control cyanobacterial blooms and to mitigate eutrophication.
使用混凝剂和压载化合物从水柱中去除蓝藻是一种有前途的减轻危害的技术。作为混凝剂，有机的、可生物降解的聚合物壳聚糖已被推广。本研究的结果表明，在蓝藻大量繁殖期间可能常见的 pH 值升高以及高碱度可能会阻碍壳聚糖的混凝作用，从而削弱其从水柱中有效去除正浮力蓝藻的能力。潜在的机制可能是带正电荷的基团被阴离子屏蔽。由于有许多壳聚糖制剂，在应用前对每种壳聚糖进行彻底测试是至关重要的。玻璃管中获得的结果与标准罐试验相似，这表明玻璃管试验可用于测试混凝剂和压载物在去除蓝藻方面的效果，同时允许更多的重复。zeta 电位与沉淀的蓝藻之间没有关系。鉴于壳聚糖众所周知的抗菌活性和最近发现的抗蓝藻作用，需要进行预应用测试，以确定壳聚糖是否会导致蓝藻毒素的细胞泄漏。效率和副作用测试对于水管理者来说至关重要，以确定所选方法是否可用于有针对性的干预措施，以控制蓝藻水华并减轻富营养化。
