Department of Civil & Environmental Engineering, Texas A&M University, College Station, Texas 77843-3136, United States.
Centers for Disease Control and Prevention, National Center for Emerging and Zoonotic Infectious Diseases, Atlanta, Georgia 30329, United States.
Environ Sci Technol. 2021 Feb 16;55(4):2674-2683. doi: 10.1021/acs.est.0c07697. Epub 2021 Feb 3.
It is imperative to understand the behavior of enveloped viruses during water treatment to better protect public health, especially in the light of evidence of detection of coronaviruses in wastewater. We report bench-scale experiments evaluating the extent and mechanisms of removal and/or inactivation of a coronavirus surrogate (ϕ6 bacteriophage) in water by conventional FeCl coagulation and Fe(0) electrocoagulation. Both coagulation methods achieved ∼5-log removal/inactivation of ϕ6 in 20 min. Enhanced removal was attributed to the high hydrophobicity of ϕ6 imparted by its characteristic phospholipid envelope. ϕ6 adhesion to freshly precipitated iron (hydr)oxide also led to envelope damage causing inactivation in both coagulation techniques. Fourier transform infrared spectroscopy revealed oxidative damages to ϕ6 lipids only for electrocoagulation consistent with electro-Fenton reactions. Monitoring ϕ6 dsRNA by a novel reverse transcription quantitative polymerase chain reaction (RT-qPCR) method quantified significantly lower viral removal/inactivation in water compared with the plaque assay demonstrating that relying solely on RT-qPCR assays may overstate human health risks arising from viruses. Transmission electron microscopy and computationally generated electron density maps of ϕ6 showed severe morphological damages to virus' envelope and loss of capsid volume accompanying coagulation. Both conventional and electro- coagulation appear to be highly effective in controlling enveloped viruses during surface water treatment.
了解包膜病毒在水处理过程中的行为对于更好地保护公众健康至关重要，尤其是在有证据表明在废水中检测到冠状病毒的情况下。我们报告了评估在实验室规模下，常规的 FeCl 混凝和零价铁（Fe(0)）电化学混凝对水中冠状病毒替代物（φ6 噬菌体）的去除和/或灭活程度及机制的实验。这两种混凝方法都在 20 分钟内实现了对 φ6 的约 5 个对数的去除/灭活。增强的去除归因于 φ6 特有的磷脂包膜赋予其的高疏水性。φ6 与新沉淀的铁（氢）氧化物的附着也导致包膜损伤，从而在两种混凝技术中导致失活。傅里叶变换红外光谱显示，仅在电混凝中对 φ6 脂质进行氧化损伤，这与电芬顿反应一致。通过一种新的逆转录定量聚合酶链反应（RT-qPCR）方法监测 φ6 的 dsRNA，与噬菌斑测定法相比，水中病毒的去除/灭活明显减少，这表明仅依赖 RT-qPCR 测定法可能夸大了病毒对人类健康的风险。φ6 的透射电子显微镜和计算生成的电子密度图显示，病毒包膜受到严重的形态损伤，伴随混凝作用，衣壳体积丢失。常规混凝和电混凝在地表水的处理过程中似乎都能非常有效地控制包膜病毒。
