预氯化对铝盐混凝铜绿微囊藻过程中溶解性有机物和残余铝的影响

以铜绿微囊藻为对象,研究了预氯化过程中藻胞内代谢物释放及铝盐混凝除藻过程中残留铝的变化规律.结果表明,氯投量对胞内物质释放量和释放有机物特征有重要影响.与未投加氯的对照体系相比,在较低氯投量时(1~2 mg·L-1),水中有机物浓度升高26%~31%,UV254值升高46%~49%,且有机物主要为中等分子量(2191、2830和3168 Da)和高芳香度的有机物.增大氯投量至3~4 mg·L-1,水中有机物浓度和UV254值有所下降;就不同分子量有机物而言,大分子量有机物(16304 Da)浓度升高而中等分子量有机物(2830、3168和6163 Da)浓度下降,且出现少量小分子量有机物(180 Da).分子量较大或芳香度较高的溶解性有机物在铝盐混凝中可被优先去除.释放到水中的蛋白质能与铝盐形成可溶性蛋白质-混凝剂复合物,从而导致出水铝浓度升高,但增大铝投量可在一定程度上降低残留铝浓度.

Effect of pre-chlorination on intracellular organic matter (IOM) release and residual aluminum in Microcystis aeruginosa coagulation by aluminum

Pre-chlorination contributes to the inactivation of Microcystis aeruginosa and the release of intracellular organic matter (IOM), and the doses of chlorine show significant effects on these processes. As compared to the control system (0 mg·L^-1 Cl₂), chlorine at low doses of 1~2 mg·L^-1 enhances the IOM release by 26%~31% and UV₂₅₄ increase by 46%~49%, mainly due to the elevated levels of IOM with moderate molar weight (MW) and high aromaticity. At high doses of chlorine (3~4 mg·L^-1), the levels of IOM with high MW increase whereas those with moderate MW decrease, and these effects lower UV₂₅₄, the aromaticity, and the IOM concentrations accordingly. The dissolved IOM with high MW and high aromaticity may be preferentially removed by Al coagulation. The released proteins during chlorination may form soluble Al-protein complexes to increase the levels of residual Al, which decreases at elevated Al doses.