Fate of indicator microorganisms, giardia and cryptosporidium in subsurface flow constructed wetlands

Thurston, Jeanette A.; Gerba, Charles P.; Foster, Kennith E.; Karpiscak, Martin M.

doi:10.1016/s0043-1354(00)00414-0

Cited by 84 publications

(51 citation statements)

References 4 publications

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“…Regarding the latter, the tropical climate ensures relatively high temperatures and radiation, allowing year-round plant growth in CW and an increase in the microbiological activity which improves the pollutant removal efficiency [45]. WSPs and CWs are also known to reduce the level of pathogens significantly, making it a promising technology to reduce the fecal contamination of the assessed rivers [46][47][48]. This was observed in our study for the natural wetland of Boye, indicating the importance of these ecosystems for ecosystem services.…”

Section: Water Quality Improvement Optionsmentioning

confidence: 99%

Water Quality Assessment of Streams and Wetlands in a Fast Growing East African City

Troyer

Mereta

Goethals

et al. 2016

Water

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Abstract:The combination of rapid urbanization, industrialization, population growth, and low environmental awareness poses a major threat to worldwide valuable freshwater resources, which provide important ecosystem services to humans. There is an urgent need to monitor and assess these resources, as this information is indispensable for sustainable decision-making and management. In this context, we analyzed the chemical and ecological water quality of the riverine environment of a fast growing city in Southwest Ethiopia for which we proposed possible remediation options that were evaluated with an empirical model. The chemical and ecological water quality was assessed at 53 sampling locations using the oxygen Prati index and the ETHbios, which is a biotic index based on macroinvertebrates. In addition, a microbiological analysis was performed to estimate the degree of fecal contamination. Finally, we analyzed the relationship between the oxygen content and the organic pollution to simulate the effect of organics removal from waste streams on the chemical water quality. Our results showed that the average values for dissolved oxygen (4.2 mg DO¨L´1) and nutrients (0.9 mg oPO 4 3´¨L´1 and 12.8 mg TAN¨L´1) exceeded international standards. Moreover, high turbidity levels revealed that land erosion is a severe problem in the region. Along the rivers, a significant increase in oxygen consumption and in nutrient concentrations was observed, indicating organic pollution originating from different diffuse and point sources of pollution. The lack of proper sanitation also led to exceedingly high abundances of fecal coliforms in the surface water (>320 MPN¨mL´1). However, fecal contamination was strongly reduced (>92%) after the polluted river water passed Boye wetland, indicating the purification potential of natural wetlands and the importance of conserving and protecting those ecosystems. The simulation results of the model showed that water quality could be substantially improved if municipal, industrial, and institutional wastewater was efficiently collected and transported to a treatment facility. Waste stabilization ponds and constructed wetlands are highly promising techniques, as they provide a cheap, effective, reliable, and sustainable way to purify wastewater. It is advised that the environmental awareness of the people via sensitization, education, and law enforcement is increased, as this is essential for sustainable development.

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Section: Water Quality Improvement Optionsmentioning

confidence: 99%

Water Quality Assessment of Streams and Wetlands in a Fast Growing East African City

Troyer

Mereta

Goethals

et al. 2016

Water

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“…Wildlife that inhabit or visit constructed wetlands have previously been demonstrated to significantly contribute fecal coliforms (e.g., Escherichia coli and Klebsiella pneumonia) to wetlands (39). It has been suggested that wildlife play an important role in the elevation of total and fecal coliform levels in wetland effluents due to their fecal deposition (39) and the spontaneous multiplication of wildlife-derived coliforms in wetlands during summer months (9).…”

Section: Discussionmentioning

confidence: 99%

“…Horizontal wetlands usually discharge to surface waters that are frequently used for recreation or drinking water production (6). It is commonly assumed that human pathogens identified in wetland effluents originate from the wastewater (39). However, this was never proven because studies of human pathogens in wetlands (10,23,28,31,32,39,40) did not utilize molecular epidemiology techniques to differentiate pathogen species or assess their viability.…”

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confidence: 99%

“…Because the wastewater resides in wetlands, these areas can act as endemic sites supporting both propagation and transmission of human zoonotic pathogens (15). Sizing reed-bed systems for a residence time of 5 days has become a standard practice (6,31,39), leaving plenty of time for the propagation and spreading of wastewater-derived pathogens in wetland habitats via a wide variety of wildlife (12,15). Any temporal or permanent malfunctioning caused by clogged inlet pipes can cause (i) hydraulic short circuits that bypass part of the filtration area in FSF wetlands or (ii) chance SSF wetland filtration dynamics to FSF dynamics (31,40).…”

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confidence: 99%

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Propagation of Human Enteropathogens in Constructed Horizontal Wetlands Used for Tertiary Wastewater Treatment

Graczyk

Lucy

Tamang

et al. 2009

Appl Environ Microbiol

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Constructed subsurface flow (SSF) and free-surface flow (FSF) wetlands are being increasingly implemented worldwide into wastewater treatments in response to the growing need for microbiologically safe reclaimed waters, which is driven by an exponential increase in the human population and limited water resources. Wastewater samples from four SSF and FSF wetlands in northwestern Ireland were tested qualitatively and quantitatively for Cryptosporidium spp., Giardia duodenalis, and human-pathogenic microsporidia, with assessment of their viability. Overall, seven species of human enteropathogens were detected in wetland influents, vegetated areas, and effluents: Cryptosporidium parvum, C. hominis, C. meleagridis, C. muris, G. duodenalis, Encephalitozoon hellem, and Enterocytozoon bieneusi. SSF wetland had the highest pathogen removal rate (i.e., Cryptosporidium, 97.4%; G. duodenalis, 95.4%); however, most of these values for FSF were in the negative area (mean, ؊84.0%), meaning that more pathogens were discharged by FSF wetlands than were delivered to wetlands with incoming wastewater. We demonstrate here that (i) the composition of human enteropathogens in wastewater entering and leaving SSF and FSF wetlands is highly complex and dynamic, (ii) the removal and inactivation of human-pathogenic microorganisms were significantly higher at the SSF wetland, (iii) FSF wetlands may not always provide sufficient remediation for human enteropathogens, (iv) wildlife can contribute a substantial load of human zoonotic pathogens to wetlands, (v) most of the pathogens discharged by wetlands were viable, (vi) large volumes of wetland effluents can contribute to contamination of surface waters used for recreation and drinking water abstraction and therefore represent a serious public health threat, and (vii) even with the best pathogen removal rates achieved by SSF wetland, the reduction of pathogens was not enough for a safety reuse of the reclaimed water. To our knowledge, this is the first report of C. meleagridis from Ireland.

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“…The urban artificial wetland, considered as a natural alternative to technical methods of wastewater treatment, which can effectively remove nitrogen, phosphorus, heavy metals oxide, various organic substances and pathogens, and reduce BOD and TSS content in water (Thurston et al, 2001;Zhao et al, 2007). Thus, urban artificial wetlands have gradually been widely used in improving water quality in urban lake and river landscapes (Cui et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Effect of reclaimed water effluent on bacterial community structure in the Typha angustifolia L. rhizosphere soil of urbanized riverside wetland, China

Huang

Xiong

Liu

et al. 2017

Journal of Environmental Sciences

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In order to evaluate the impact of reclaimed water on the ecology of bacterial communities in the Typha angustifolia L. rhizosphere soil, bacterial community structure was investigated using a combination of terminal restriction fragment length polymorphism and 16S rRNA gene clone library. The results revealed significant spatial variation of bacterial communities along the river from upstream and downstream. For example, a higher relative abundance of γ-Proteobacteria, Firmicutes, Chloroflexi and a lower proportion of β-Proteobacteria and ε-Proteobacteria was detected at the downstream site compared to the upstream site. Additionally, with an increase of the reclaimed water interference intensity, the rhizosphere bacterial community showed a decrease in taxon richness, evenness and diversity. The relative abundance of bacteria closely related to the resistant of heavy-metal was markedly increased, while the bacteria related for carbon/nitrogen/phosphorus/sulfur cycling wasn't strikingly changed. Besides that, the pathogenic bacteria markedly increased in the downstream rhizosphere soil since reclaimed water supplement, while the possible plant growth-promoting rhizobacteria obviously reduced in the downstream sediment.Together these data suggest cause and effect between reclaimed water input into the wetland, shift in bacterial communities through habitat change, and alteration of capacity for biogeochemical cycling of contaminants.

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Fate of indicator microorganisms, giardia and cryptosporidium in subsurface flow constructed wetlands

Cited by 84 publications

References 4 publications

Water Quality Assessment of Streams and Wetlands in a Fast Growing East African City

Water Quality Assessment of Streams and Wetlands in a Fast Growing East African City

Propagation of Human Enteropathogens in Constructed Horizontal Wetlands Used for Tertiary Wastewater Treatment

Effect of reclaimed water effluent on bacterial community structure in the Typha angustifolia L. rhizosphere soil of urbanized riverside wetland, China

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