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随着全球气候变暖和江河、湖泊等水体富营养化程度加剧,蓝藻水华现象日益严重[1]。蓝藻暴发会导致水体溶解氧(DO)含量急剧降低、水生生物大量死亡,其在代谢过程中释放的具有极强肝毒性和遗传毒性的藻毒素(MCs)[2],也会对人类的生命健康造成严重威胁。根据理化性质及适用条件,传统蓝藻水华治理方法可分为物理法、化学法和生物法。物理法可在短期内大幅削减蓝藻密度,但存在二次污染、滤池堵塞及成本较高等不足[3];化学法灭藻效率高,但难以避免IOMs释放、DBPs产生及出水金属离子含量增加等环境风险[4-5];生物法操作简单、对环境影响较小,但见效周期长,且易受气候、温度等环境因素影响[6]。因此,如何高效、安全地治理蓝藻水华,已成为国内外学者关注和研究的热点。
AOPs是一种通过诱发链式反应产生·OH或
${\rm{SO}}_4^{-}\cdot $ 等自由基[7],从而降解有机污染物的水处理技术,具有操作简便、反应条件温和等优点。但目前的研究主要集中于产生·OH的AOPs,有关产生硫酸根自由基(${\rm{SO}}_4^{-}\cdot $ )的AOPs研究相对甚少。${\rm{SO}}_4^{-}\cdot $ 氧化还原电位为2.50~3.10 V,高于·OH(2.80 V)和O3(2.07 V)[8],并且同·OH相比,${\rm{SO}}_4^{-}\cdot $ 具有选择性强、受pH影响小以及半衰期更长等优点。基于AOPs产生的${\rm{SO}}_4^{-}\cdot $ ,可以通过UV辐照、过渡金属离子和氧化剂协同等方式催化PMS或过硫酸盐(PS)来实现[9]。本研究以铜绿微囊藻为研究对象,探究了在FeSO4-PMS体系中FeSO4投加量、pH、HPO42−及${\rm{NO}}_3^{-} $ 对藻细胞去除效果的影响,同时对藻液中溶解性有机碳(DOC)含量和UV254进行了测定;结合三维荧光光谱(EEM)、Zeta电位以及扫描电镜(SEM)等分析表征方法对藻细胞的去除机理进行了探究,以期为FeSO4-PMS治理蓝藻水华提供参考。
硫酸亚铁协同过硫酸氢钾去除铜绿微囊藻
Removal of Microcystis aeruginosa by synergy of ferrous sulfate and potassium hydrogen persulfate
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摘要: 避免消毒副产物(DBPs)形成和胞内有机物(IOMs)的释放,是解决传统工艺治理蓝藻水华潜在风险的关键。为此,开展了FeSO4协同过硫酸氢钾(PMS)高级氧化除藻研究,分别探讨了FeSO4投加量、pH及无机离子对铜绿微囊藻细胞去除效果的影响。结果表明:当FeSO4和PMS投加量均为0.1 mmol·L−1时,藻细胞、DOC和UV254的去除率分别为94.66%、58.92%和41.52%,藻细胞去除的氧化、絮凝的贡献率分别为30.50%和69.50%;当pH为6.0~10.0时,藻细胞去除率均保持较高水平,其中弱酸环境有利于提高藻细胞的去除;外加的HPO42−和
${{\rm{NO}}_3^{-}} $ 对${{\rm{SO}}_4^{-}\cdot }$ 的竞争抑制,可导致藻细胞去除率降低;FeSO4-PMS可以有效去除含有荧光特性的藻源性有机质(AOMs);当FeSO4投加量低于0.1 mmol·L−1时,藻细胞、叶绿素a去除率随着Zeta电位净值降低而升高。扫描电镜表征结果表明,协同氧化后大多数藻细胞形态结构完整,从而可有效避免IOMs释放。以上研究结果可为FeSO4-PMS治理富营养化水体中蓝藻水华提供参考。Abstract: Avoiding the formation of disinfection by-products (DBPs) and the release of intracellular organic matters (IOMs) are keys to resolve the potential risks of cyanobacterial blooms treated by traditional techniques. In this study, the advanced oxidation technology based on FeSO4 combined with potassium monopersulfate (PMS) for the treatment of Microcystis aeruginosa cells was investigated. The effects of FeSO4 dosage, pH and inorganic ions on the removal rates of Microcystis aeruginosa were studied. Results showed that when the doses of FeSO4 and PMS were controlled at 0.1 mmol·L−1, algal cell count, DOC concentration and UV254 measurements were reduced by 94.66%, 58.92% and 41.52%, respectively. The oxidation and flocculation process contributed to the algae cell removal rates were 30.50% and 69.50%, respectively. The removal rates of Microcystis aeruginosa could maintained at a high level when the pH was in the rage of 6.0~10.0, especial with mild acidic conditions. Due to competitive inhibition of${\rm{SO}}_4^{-}\cdot $ by extra added HPO42− and${\rm{NO}}_3^{-} $ , the removal efficiencies of algae cells began to decrease. FeSO4-PMS could effectively degrade organic matters (AOMs) with fluorescence characteristics. While the dosage of FeSO4 was below 0.1 mmol·L−1, the removal rate of algae cells and Chl-a increased with the decrease of the absolute Zeta potential. Scanning electron microscopy analysis also showed that most of algae cells had non-destructive morphology and structure after coordinated oxidation, which indicated this process effectively avoiding the release of IOMs. The above results can provide theoretical foundation for FeSO4-PMS treating cyanobacteria blooms in eutrophic water bodies. -
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