King Brendon, Fanok Stella, Phillips Renae, Lau Melody, van den Akker Ben, Monis Paul
South Australian Water Corporation, Adelaide, SA, Australia
South Australian Water Corporation, Adelaide, SA, Australia.
Appl Environ Microbiol. 2017 Feb 15;83(5). doi: 10.1128/AEM.03068-16. Print 2017 Mar 1.
Compliance with guideline removal targets for which do not provide any credit for the inactivation of oocysts through wastewater treatment processes can considerably increase the cost of providing recycled water. Here we present the application of an integrated assay to quantify both oocyst numbers and infectivity levels after various treatment stages at three Victorian and two South Australian (SA) wastewater treatment plants (WWTPs). Oocyst density in the raw sewage was commensurate with community disease burden, with early rounds of sampling capturing a widespread cryptosporidiosis outbreak in Victoria. The level of infectivity of oocysts in sewage was stable throughout the year but was significantly lower at the SA WWTPs. Removals across secondary treatment processes were seasonal, with poorer removals associated with inflow variability; however, no decrease in the oocyst infectivity was identified. For SA WWTPs, those oocysts remaining within the secondary treatment-clarified effluent were proportionally more infectious than those in raw sewage. Lagoon systems demonstrated significant inactivation or removal of oocysts, with attenuation being seasonal. Examination of a UV system emphasized its efficacy as a disinfectant barrier but conversely confirmed the importance of a multibarrier approach with the detection of infectious oocysts postdisinfection. The ability to characterize risk from infectious oocysts revealed that the risk from is significantly lower than previously thought and that its inclusion in quantitative risk assessments of reuse systems will more accurately direct the selection of treatment strategies and capital expenditure, influencing the sustainability of such schemes. Here we present the application of a recently developed integrated assay not only to quantify the removal of oocysts but also to quantify their infectivity across various treatment stages at five wastewater treatment plants (WWTPs), thereby better measuring the "true effect" of the treatment train on oocyst risk reduction. For a number of the WWTPs analyzed in this study the risk, is significantly lower than previously thought. Therefore, the inclusion of oocyst infectivity in guideline values and in quantitative microbial risk assessment (QMRA) has the potential to affect future treatment directions and capital expenditure.
对于那些未考虑通过污水处理工艺使卵囊失活的指南去除目标，严格遵守这些目标会大幅增加提供再生水的成本。在此，我们展示了一种综合检测方法的应用，用于量化三个维多利亚州和两个南澳大利亚州（SA）污水处理厂（WWTPs）在不同处理阶段后的卵囊数量和感染性水平。原污水中的卵囊密度与社区疾病负担相当，早期采样轮次捕捉到了维多利亚州广泛的隐孢子虫病疫情。污水中卵囊的感染性水平全年稳定，但在南澳大利亚州的污水处理厂显著较低。二级处理过程中的去除率具有季节性，去除效果较差与进水变化有关；然而，未发现卵囊感染性降低。对于南澳大利亚州的污水处理厂，二级处理澄清出水中残留的那些卵囊比原污水中的卵囊具有更高的感染性。泻湖系统显示出对卵囊有显著的失活或去除作用，其衰减具有季节性。对紫外线系统的检查强调了其作为消毒屏障的功效，但相反也证实了多屏障方法的重要性，因为在消毒后检测到了感染性卵囊。对感染性卵囊的风险进行特征描述的能力表明，其风险明显低于先前的认识，并且将其纳入回用系统的定量风险评估中将更准确地指导处理策略的选择和资本支出，影响此类方案的可持续性。在此，我们展示了一种最近开发的综合检测方法的应用，不仅用于量化卵囊的去除，还用于量化其在五个污水处理厂不同处理阶段的感染性，从而更好地衡量处理流程对降低卵囊风险的“真实效果”。对于本研究中分析的许多污水处理厂，其风险明显低于先前的认识。因此，在指南值和定量微生物风险评估（QMRA）中纳入卵囊感染性可能会影响未来的处理方向和资本支出。
