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. 2020 Feb 3;16(1):13.
doi: 10.1186/s12992-020-0546-y.

Effectiveness of wastewater treatment systems in removing microbial agents: a systematic review

Zahra Aghalari  1 , Hans-Uwe Dahms  2   3   4 , Mika Sillanpää  5 , Juan Eduardo Sosa-Hernandez  6 , Roberto Parra-Saldívar  6
Affiliations

Effectiveness of wastewater treatment systems in removing microbial agents: a systematic review

Zahra Aghalari et al. Global Health. .

Abstract

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.

Keywords: Articles; Environmental health; Journals; Microbial agents; Systematic analysis; Treatment; Wastewater.

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Conflict of interest statement

The authors declare that they have no competing interests.

Figures

Fig. 1
Fig. 1
Flowchart describing the study design
Fig. 2
Fig. 2
Cities selected for wastewater sampling in 14 articles
Fig. 3
Fig. 3
Types of microbial agents removed in wastewater based on the articles
See this image and copyright information in PMC

References

    1. Qu X, Zhao Y, Yu R, Li Y, Falzone C, Smith G, Ikehata K. Health effects associated with wastewater treatment, reuse, and disposal. Water Environ Res. 2016;88(10):1823–1855. doi: 10.2175/106143016X14696400495776. - DOI - PubMed
    1. Choudri BS, Charabi Y, Ahmed M. Health effects associated with wastewater treatment, Reuse and Disposal. Water Environ Res. 2018;90(10):1759–1776. doi: 10.2175/106143018X15289915807425. - DOI - PubMed
    1. Zhang QH, Yang WN, Ngo HH, Guo WS, Jin PK, Dzakpasu M, Yang SJ, Wang Q, Wang XC, Ao D. Current status of urban wastewater treatment plants in China. Environ Int. 2016;92-93:11–22. doi: 10.1016/j.envint.2016.03.024. - DOI - PubMed
    1. Nzila A, Razzak SA, Zhu J. Bioaugmentation: an emerging strategy of industrial wastewater treatment for reuse and discharge. Int J Environ Res Public Health. 2016;13(9):846. doi: 10.3390/ijerph13090846. - DOI - PMC - PubMed
    1. Norton-Brandao D, Scherrenberg SM, van Lier JB. Reclamation of used urban waters for irrigation purposes—a review of treatment technologies. J Environ Manag. 2013;122:85–98. doi: 10.1016/j.jenvman.2013.03.012. - DOI - PubMed

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