Abstract

Cyanotoxins, produced from cyanobacteria-dominated harmful algal blooms (cHABs), pose a threat to ecosystems, as well as drinking water systems. Disinfection via chlorine is the last step in a conventional drinking water treatment plant (DWTP) to remove any extracellular toxins present in the water. This research investigated the impact of pH on the oxidation of different saxitoxin (STX) and anatoxin-a (ANTX-a) concentrations in the post-filtration water collected from two DWTPs. STX degradation was the most efficient at higher pH levels. For instance, pH 6 resulted in 13–43% degradation and pH 9 resulted in 56–74% degradation of STX. The presence of microcystin-LR (MC-LR) did not significantly inhibit the removal of STX, with STX removal (at pH 6–8) higher than when MC-LR was not present. A dose of 1.8 mg/L chlorine and 235-min contact achieved 38% removal of ANTX-a while the dose of 3.2 mg/L chlorine and the contact time of 118 min removed 75% of ANTX-a at pH 6.

中文翻译：

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pH 对石房蛤毒素和鱼腥藻毒素-a 氯氧化的影响

摘要

由蓝藻为主的有害藻华 (cHAB) 产生的蓝毒素对生态系统以及饮用水系统构成威胁。氯消毒是传统饮用水处理厂 (DWTP) 的最后一步，用于去除水中存在的任何细胞外毒素。本研究调查了 pH 值对从两个 DWTP 收集的过滤后水中不同浓度的石房蛤毒素 (STX) 和虾毒素 -a (ANTX-a) 氧化的影响。STX 降解在较高 pH 水平下最有效。例如，pH 6 导致 STX 降解 13-43%，pH 9 导致 STX 降解 56-74%。微囊藻毒素-LR (MC-LR) 的存在不会显着抑制 STX 的去除，STX 的去除率（pH 6-8）高于 MC-LR 不存在时的去除率。在 pH 6 时，1.8 mg/L 氯剂量和 235 分钟接触可实现 38% 的 ANTX-a 去除，而 3.2 mg/L 氯剂量和 118 分钟接触时间可去除 75% ANTX-a。