Pre-chlorination is usually applied to facilitate coagulation process when treating cyanobacteria-laden source waters. However, the responses of cyanobacteria after chlorination were varied in different growth phases, hence how these differences affect the coagulation is not clear. In this study, Microcystis aeruginosa (M. aeruginosa) in late lag and exponential phases were selected for comparing the remove effect of cyanobacterial coagulation after varied doses (0, 0.5, 1.0 and 2.0 mg/L) of pre-chlorination. Results showed that the M. aeruginosa in late lag phase held higher removal efficiencies (48-86%) than those in exponential phase (1-60%). Lower pH and buoyancy, higher Zeta potential and hydrophobicity were beneficial to its coagulation. The application of 0.5-2.0 mg/L pre-chlorination in late lag phase did not promote its coagulation, mainly due to the impediment by released hydrophilic humus. In contrast, the remove efficiency increased about 40% with the addition of 2.0 mg/L chlorine and 15 mg/L polyaluminum chloride (PACl) in exponential phase. The increased macromolecular organic matters, Zeta potential and decreased buoyancy made for this promotion. In addition, the removal of extracellular organic matters, aromatics and microcystin was not that productive after coagulation in exponential phase, but both of chlorination and coagulation could reduce microcystin in late lag phase. The findings suggest that optimizing the application methods of pre-chlorine and coagulant according to the growth phases is necessary for cyanobacterial control.

中文翻译：

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晚期滞后期和指数期的蓝细菌适合不同的预氯化和凝结策略


在处理含蓝藻的源水时，通常会进行预氯化处理，以促进混凝过程。然而，蓝藻氯化后的反应在不同的生长期是不同的，因此这些差异如何影响凝血尚不清楚。在本研究中，选择了晚期滞后期和指数期的铜绿微囊藻 （M. aeruginosa） 来比较不同剂量 （0、0.5、1.0 和 2.0 mg/L） 预氯化后蓝藻凝固的去除效果。结果表明，滞后后期铜绿假单胞菌的去除效率 （48-86%） 高于指数期的铜绿假单胞菌 （1-60%）。较低的 pH 值和浮力、较高的 Zeta 电位和疏水性有利于其凝血。在滞后期施用 0.5—2.0 mg/L 预氯化并未促进其凝固，主要是由于释放的亲水性腐殖质的阻碍。相比之下，在指数相添加 2.0 mg/L 氯和 15 mg/L 聚合氯化铝 （PACl） 时，去除效率提高了约 40%。增加的大分子有机物、Zeta 电位和降低的浮力为这种推广做出了贡献。此外，指数期凝固后细胞外有机物、芳香族化合物和微囊藻毒素的去除效率不高，但氯化和凝结均可降低滞后期微囊藻毒素。研究结果表明，根据生长阶段优化预氯和混凝剂的施用方法是控制蓝藻的必要条件。