Removal of Pathogenic Bacteria in Constructed Wetlands: Mechanisms and Efficiency

Stefanakis, Alexandros I.; Akratos, Christos S.

doi:10.1007/978-3-319-41811-7_17

Cited by 14 publications

(12 citation statements)

References 75 publications

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“…Pathogen treatment in wetlands relies on different mechanisms including sedimentation, natural die-off, temperature, oxidation processes, predation, water chemistry, adhesion to biofilm, mechanical filtration, exposure to biocides and UV radiation (Gerba et al, 1999;Vymazal, 2005;Alexandros and Akratos, 2016). With all these mechanisms in mind, some of the most prevalent latent variables that are not described with a simple firstorder aerial based rate constant are substrate type, plant type, microbial ecology and activity within the CW system, biofilm interactions, temperature, incoming water quality, and wetland depth.…”

Section: Microbial Indicatorsmentioning

confidence: 99%

“…It is known that these systems could act as excellent bacterial sinks through a combination of complexes physical, chemical and biological factors that actively participate in the reduction of the number of bacteria present in water (Vymazal, 2005;Wu et al, 2016). In the last 15 years, significant resources have been invested to improve the understanding of the mechanisms involved in the removal of microbes at decentralized systems (Arias et al, 2003;Hansen et al, 2004;Ibekwe et al, 2003;Karim et al, 2004;Vacca et al, 2005;Winward et al, 2008;Adrados et al, 2014;Morató et al, 2014;Wu et al, 2016;Alexandros and Akratos, 2016;Akunna et al, 2017). However, there is still a lack of information from comparative studies evaluating the removal of microbes between natural wastewater treatment systems actively working during long-term operation periods.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of removal efficiency of pathogenic microbes in four types of wastewater treatment systems in Denmark

Adrados

Arias

Pérez

et al. 2018

Ecological Engineering

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The aim of the present work was to evaluate and compare the performance in the removal of pathogenic microbes in four different types of decentralized wastewater treatment systems, namely: horizontal flow constructed wetlands (HFCW), vertical flow constructed wetlands (VFCW), biological sand filters (BSF) and biofilters (BF). All the systems analyzed are located in Jutland, Denmark. Water sampling took place during a three months period that covered from winter to spring. Conventional microbial indicators such as Escherichia coli, total coliforms (TC), intestinal enterococci and sulphite-reducing clostridia were quantified using traditional microbiological culture methods, whereas Bacteroides spp. determination was performed by quantitative PCR (qPCR). Other water quality parameters such as dissolved oxygen, biological oxygen demand (BOD 5), total suspended solids (TSS), pH, temperature, ammonium concentration and conductivity of influent and effluent water samples were also analyzed. The results showed that bacterial indicators significantly reduced in all the systems analyzed. In general, BF showed the best performance in the removal of microbes for all bacteria studied, while BSF demonstrated an improved capacity to eliminate E. coli and TC. Contrarily, VFCW seems to be more effective reducing the amount of intestinal enterococci, sulphite-reducing clostridia, and Bacteroides spp. In the present study, HFCW were the less efficient wastewater treatment system for the elimination of the evaluated pathogens. However, the performance in the removal of microbes was still significant considering that such systems were the oldest under operation (with over 20 years of continuous task).

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Section: Microbial Indicatorsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Comparison of removal efficiency of pathogenic microbes in four types of wastewater treatment systems in Denmark

Adrados

Arias

Pérez

et al. 2018

Ecological Engineering

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“…Examples of low cost multi-barrier approach could be coagulation, flocculation and sedimentation (typically achieves 1 log reduction 53 ), followed by retention of supernatant in evaporation ponds or wetlands (typically achieves 1 to 2 log reduction 54,55 ), and then surface spreading for infiltration of the water through sand gravel layers prior to storage in underground aquifers (typically achieves 1 log reduction for every 8.5 m of infiltration 53,56 ). The stored water can then be pumped up from the aquifer and disinfected (typically achieves 3 log reduction) before using for agricultural irrigation.…”

Section: Multi-barrier Intervention Strategies For Low Resource Countmentioning

confidence: 99%

Mitigating Antimicrobial Resistance Risks When Using Reclaimed Municipal Wastewater for Agriculture

Hong

Wang

Mantilla‐Calderon

2020

The Handbook of Environmental Chemistry

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The global need for food is posing a serious threat to water security. Treated wastewater can be used as an alternative water supply to mitigate our reliance on non-renewable waters (defined as water that cannot be replenished within our life span). However, concerns related to emerging contaminants such as antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) can impede efforts to push for widespread use of treated wastewater in agricultural irrigation. This chapter aims to provide a better understanding of the potential concerns by first using case studies in two countries that have already practiced water reuse. Second, we collate and analyze data that suggests that wastewater treatment plants able to achieve at least 8-log reduction in microbiological contaminants may suffice as appropriate intervention barriers for ARB dissemination to the environment. This chapter also recognizes that extracellular DNA carrying ARGs may not be effectively removed even with membranebased treatment. There is therefore a need to assess whether extracellular DNA may accumulate in agricultural soils due to repeated use of treated wastewater, and to determine the concentrations of extracellular DNA needed to significantly increase horizontal gene transfer (HGT) in the natural environment. Given the large knowledge gaps that hinder an accurate assessment of the associated risks, it would be prudent to adopt the precautionary principle and to implement appropriate intervention strategies and best management practices that minimize the impacts and concerns arising from the reuse of treated wastewater in agriculture.

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“…The microbial community in a CW consists of autochthonous (indigenous) and allochthonous (exogenous) microorganisms [ 25 , 26 ]. Autochthonous microorganisms are able to survive and grow in wetland systems during purification processes, while most allochthonous microbes (including pathogens entering with wastewater) do not survive or have any functional importance in the wetland environment [ 25 , 27 , 28 ]. Autochthonous microorganisms mediate many processes involved in the purification of wastewater in CWs.…”

Section: Introductionmentioning

confidence: 99%

Spatial Changes in Microbial Communities along Different Functional Zones of a Free-Water Surface Wetland

et al. 2020

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Constructed wetlands (CWs) are complicated ecosystems that include vegetation, sediments, and the associated microbiome mediating numerous processes in wastewater treatment. CWs have various functional zones where contrasting biochemical processes occur. Since these zones are characterized by different particle-size composition, physicochemical conditions, and vegetation, one can expect the presence of distinct microbiomes across different CW zones. Here, we investigated spatial changes in microbiomes along different functional zones of a free-water surface wetland located in Moscow, Russia. The microbiome structure was analyzed using Illumina MiSeq amplicon sequencing. We also determined particle diameter and surface area of sediments, as well as chemical composition of organic pollutants in different CW zones. Specific organic particle aggregates similar to activated sludge flocs were identified in the sediments. The highest accumulation of hydrocarbons was found in the zones with predominant sedimentation of fine fractions. Phytofilters had the highest rate of organic pollutants decomposition and predominance of Smithella, Ignavibacterium, and Methanothrix. The sedimentation tank had lower microbial diversity, and higher relative abundances of Parcubacteria, Proteiniclasticum, and Macellibacteroides, as well as higher predicted abundances of genes related to methanogenesis and methanotrophy. Thus, spatial changes in microbiomes of constructed wetlands can be associated with different types of wastewater treatment processes.

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Removal of Pathogenic Bacteria in Constructed Wetlands: Mechanisms and Efficiency

Cited by 14 publications

References 75 publications

Comparison of removal efficiency of pathogenic microbes in four types of wastewater treatment systems in Denmark

Comparison of removal efficiency of pathogenic microbes in four types of wastewater treatment systems in Denmark

Mitigating Antimicrobial Resistance Risks When Using Reclaimed Municipal Wastewater for Agriculture

Spatial Changes in Microbial Communities along Different Functional Zones of a Free-Water Surface Wetland

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