BACKGROUND Due to unrestricted entry of wastewater into the environment and the transportation of microbial contaminants to humans and organisms, environmental protection requires the use of appropriate purification systems with high removal efficiency for microbial agents are needed. The purpose of this study was to determine the efficacy of current wastewater treatment systems in removing microbes and their contaminants. METHODS A systematic review was conducted for all articles published in 5 Iranian environmental health journals in 11 years. The data were collected according to the inclusion and exclusion criteria and by searching the relevant keywords in the articles published during the years (2008-2018), with emphasis on the efficacy of wastewater treatment systems in removing microbial agents. Qualitative data were collected using a preferred reporting items for systematic reviews and meta-analyzes (PRISMA) standard checklist. After confirming the quality of the articles, information such as the name of the first author and the year of publication of the research, the type of study, the number of samples, the type of purification, the type of microbial agents and the rate of removal of microbial agents were entered into the checklist. Also the removal rates of the microbial agents mentioned in the studies were compared with united states environmental protection agency (US-EPA) standards. RESULTS In this study, 1468 articles retrieved from 118 issues of 5 environmental health journals were reviewed. After reviewing the quality of the articles in accordance with the research objectives, 14 articles were included in the study that were published between 2010 and 2018. In most studies, two main indicators Total coliforms and Fecal coliforms in wastewater were investigated. Removing fungi and viral contamination from wastewater was not found in any of the 14 studies. Different systems (activated sludge, stabilization ponds, wetlands, and low and medium pressure UV disinfection systems were used to remove microbial agents in these studies. Most articles used active sludge systems to remove Total coliforms and Fecal coliforms, which in some cases were not within the US-EPA standard. The removal of Cysts and Parasitic eggs was only reporte from stabilization pond systems (SPS) where removal efficiency was found in accordance with US-EPA standards. CONCLUSIONS Different types of activated sludge systems have higher efficacy to remove microbial agents and are more effective than other mentioned systems in removing the main indicators of sewage contamination including Total coliforms and Fecal coliforms. However, inappropriate operation, maintenance and inadequate handling of activated sludge can also reduce its efficiency and reduce the removal of microbial agents, which was reported in some studies. Therefore, it is recommended to conduct research on how to improve the operation, maintenance, and proper management of activated sludge systems to transfer knowledge to users of sludge systems and prevent further health issues related to microbial agents.

中文翻译：

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废水处理系统去除微生物制剂的有效性：系统综述。

背景技术由于废水不受限制地进入环境以及微生物污染物向人类和有机体的运输，环境保护需要使用对微生物剂具有高去除效率的适当净化系统。这项研究的目的是确定当前废水处理系统在去除微生物及其污染物方面的功效。方法对11年内在5种伊朗环境卫生杂志上发表的所有文章进行了系统的综述。根据纳入和排除标准并通过搜索多年来（2008-2018年）发表的文章中的相关关键字来收集数据，重点是废水处理系统去除微生物剂的功效。使用首选报告项收集定性数据，以进行系统评价和荟萃分析（PRISMA）标准清单。确认文章的质量之后，请提供第一作者的姓名和研究年份，研究类型，样品数量，纯化类型，微生物剂类型和使用率等信息。去除微生物制剂被输入清单。还将研究中提到的微生物剂的去除率与美国环境保护局（US-EPA）的标准进行了比较。结果在本研究中，对从5种环境健康期刊的118期中检索到的1468篇文章进行了审查。在根据研究目标审查了文章的质量之后，该研究包括14篇文章，于2010年至2018年之间发表。在大多数研究中，对废水中的大肠菌群和粪大肠菌群的两个主要指标进行了调查。在这14项研究中，没有发现从废水中去除真菌和病毒污染。在这些研究中，使用了不同的系统（活性污泥，稳定池，湿地以及低压和中压紫外线消毒系统）来去除微生物。大多数文章使用活性污泥系统来去除总大肠菌和粪便大肠菌，在某些情况下不在仅从稳定化池塘系统（SPS）中报告了囊肿和寄生虫卵的去除，在该系统中，去除率符合US-EPA标准。结论不同类型的活性污泥系统在去除微生物物质方面具有更高的功效，并且在去除污水污染的主要指标（包括大肠菌和粪便大肠菌）方面比其他提到的系统更有效。然而，一些研究报告称，活性污泥的不当操作，维护和不当处理也会降低其效率并减少微生物的去除。因此，建议进行有关如何改善活性污泥系统的操作，维护和适当管理的研究，以将知识转移给污泥系统的用户，并防止与微生物制剂有关的进一步健康问题。