Protozoan predation as a mechanism for the removal of cryptosporidium oocysts from wastewaters in constructed wetlands

2001 ◽  
Vol 44 (11-12) ◽  
pp. 191-198 ◽  
Author(s):  
R. Stott ◽  
E. May ◽  
E. Matsushita ◽  
A. Warren
Keyword(s):  
Constructed Wetlands ◽  
Protozoan Parasite ◽  
Epifluorescence Microscopy ◽  
Free Living ◽  
Feeding Experiments ◽  
Treatment Processes ◽  
Ciliate Species ◽  
Cryptosporidium Oocysts ◽  
The Uk ◽  
Stylonychia Mytilus

The removal of the protozoan parasite, Cryptosporidium parvum, from wastewaters is becoming of increasing importance in the UK, especially since contamination of raw waters by sewage effluents has been implicated in major waterborne outbreaks of cryptosporidiosis in recent years. Compared to conventional wastewater-treatment processes, constructed wetlands have demonstrated favourable removal rates for Cryptosporidium oocysts. The removal mechanisms, however, remain unknown. Predation by free-living ciliated protozoa, which are commonly found in constructed wetlands, was investigated as a possible mechanism for oocyst removal. In laboratory feeding experiments, ciliates (Euplotes patella, Stylonychia mytilus, Paramecium caudatum and an unidentified wetland ciliate species), were exposed to doses ranging from 10 to 106 oocysts/ml for between 5 and 60 minutes. Ciliate predatory activities were assessed by enumerating fluorescently labelled ingested oocysts using epifluorescence microscopy. Oocysts were found to be ingested by all species investigated. Paramecium demonstrated the highest mean ingestion rates (up to 170 oocysts/hr) followed by Stylonychia (up to 60 oocysts/hour). Euplotes and the wetland ciliate had lower mean grazing rates (4 and 10 oocysts/hr respectively). These results indicate that protozoan predation may be an important factor in the removal of Cryptosporidium oocysts from wastewaters in constructed wetlands.

Predation of Cryptosporidium oocysts by protozoa and rotifers: implications for water quality and public health

2003 ◽  
Vol 47 (3) ◽  
pp. 77-83 ◽  
Author(s):  
R. Stott ◽  
E. May ◽  
E. Ramirez ◽  
A. Warren
Keyword(s):  
Aquatic Ecosystems ◽  
Wastewater Treatment Plants ◽  
Ciliated Protozoa ◽  
Free Living ◽  
Predator Species ◽  
Cryptosporidium Oocysts ◽  
Cryptosporidium Parvum Oocysts ◽  
Acanthamoeba Culbertsoni ◽  
Dose Levels ◽  
Stylonychia Mytilus

Predation by free-living protozoa and rotifers was investigated as a possible mechanism for the removal of Cryptosporidium parvum oocysts in aquatic ecosystems including wastewater treatment plants. Free-living ciliated protozoa (Stylonychia mytilus, Paramecium caudatum and an unidentified wastewater wetland ciliate), an amoeba (Acanthamoeba culbertsoni) and rotifers, all commonly found in aquatic ecosystems, were exposed to varying doses of C. parvum oocysts. All organisms investigated ingested oocysts. Predation activity and rates of ingestion varied with predator species and prey density. Ciliated protozoa demonstrated greater predation activity than A. culbertsoni or rotifers when exposed to 2 × 105 oocyst/mL for up to 3 h. Greatest predation after 1 h exposure was observed in P. caudatum, the largest ciliate, with on average 1.9 oocysts/cell (range 0-9 oocysts/cell). Stylonychia mytilus and the wetland ciliate had a similar mean ingestion of around 0.3 oocysts/cell, with numbers internalised ranging from 0-3 oocysts/cell. Rotifers ingested on average 1.6 oocysts/individual (range 0-7 oocysts/individual) whilst amoebae ingested on average 1.8 oocysts/cell after 2 h exposure (up to 3 oocysts/cell). Grazing activity by P. caudatum was demonstrated at a variety of prey levels ranging from 9 to 9,000 oocysts. Numbers of oocysts internalised by Paramecium frequently exceeded the reported human infective dose of 30 oocysts. In general, numbers of internalised oocysts increased with incubation time of up to 20-30 min although the rate of accumulation was slower at lower dose levels. The significance of predation on the fate of Cryptosporidium oocysts in the environment is discussed.

scholarly journals Removal of Cryptosporidium by wastewater treatment processes: a review

2015 ◽  
Vol 14 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Abidelfatah M. Nasser
Keyword(s):  
Animal Species ◽  
Protozoan Parasite ◽  
High Rate ◽  
Environmental Stability ◽  
Infectious Dose ◽  
Chlorine Disinfection ◽  
Untreated Wastewater ◽  
Treatment Processes ◽  
Cryptosporidium Oocysts ◽  
Suitable Treatment

Cryptosporidium is a protozoan parasite that infects humans and various animal species. The environmental stability and the low infectious dose of Cryptosporidium facilitate its transmission by water and food. Discharge of untreated wastewater may result in waterborne or foodborne Cryptosporidium outbreaks, therefore a suitable treatment may prevent its dissemination. Most studies on the prevalence of Cryptosporidium oocysts in wastewater have reported a concentration range between 10 and 200 oocysts/L and a prevalence of 6 to 100%. Activated sludge has been found to be ineffective for the removal of Cryptosporidium oocysts. Stabilization ponds and constructed wetlands are efficient for the reduction of Cryptosporidium from wastewater, especially when the retention time is longer than 20 days at suitable sunlight and temperature. High rate filtration and chlorine disinfection are inefficient for the reduction of Cryptosporidium from effluents, whereas ultrafiltration and UV irradiation were found to be very efficient for the reduction of Cryptosporidium oocysts. Adequate tertiary treatment may result in high quality effluent with low risk of Cryptosporidium for unrestricted irrigation and other non-potable applications.

Cryptosporidium removal during water treatment using dissolved air flotation

1995 ◽  
Vol 31 (3-4) ◽  
pp. 125-135 ◽  
Author(s):  
T. Hall ◽  
J. Pressdee ◽  
R. Gregory ◽  
K. Murray
Keyword(s):  
Water Treatment ◽  
Metal Ion ◽  
Ion Concentration ◽  
Sudden Increase ◽  
Water Turbidity ◽  
Dissolved Air Flotation ◽  
Treatment Processes ◽  
Air Flotation ◽  
The Uk ◽  
Dissolved Air

The occurrence of the protozoan parasite Cryptosporidium parvum in water supplies, and the resultant outbreaks of cryptosporidiosis in the UK and USA, have led to concern over the ability of conventional water treatment processes to remove Cryptosporidia from water sources. Large scale pilot plant trials of water treatment have been carried out in the UK to establish the degree of removal that can be achieved by a range of treatment processes, including dissolved air flotation, and to compare the performance of different treatment options. Results from part of these trials are presented in this paper. These results suggest that well operated chemical coagulation based treatment, using either dissolved air flotation or floc blanket clarification, should be capable of achieving removal of Cryptosporidium oocysts of over 99%. There was no evidence of differences in performance between the different types of filter media investigated. The risk of increased Cryptosporidium concentration in the filtered water will increase as filtrate turbidity increases. However, other factors such as high coagulant metal-ion concentration in the filtered water, or a sudden increase in clarified water turbidity, without any increase in filtered water turbidity, may also indicate treatment problems and associated risk from Cryptosporidia. Recycling of backwash waters may also increase the risk.

Constructed wetlands in UK urban surface drainage systems

2005 ◽  
Vol 51 (9) ◽  
pp. 31-37 ◽  
Author(s):  
B. Shutes ◽  
J.B. Ellis ◽  
D.M. Revitt ◽  
L.N.L. Scholes
Keyword(s):  
Constructed Wetlands ◽  
Design Criteria ◽  
Road Runoff ◽  
Agenda 21 ◽  
Drainage Systems ◽  
Potential Benefits ◽  
Guidance Documents ◽  
Environment Agency ◽  
And Performance ◽  
The Uk

This paper presents the outcome of an inventory of planted wetland systems in the UK which are classified according to land use type and are all examples of sustainable drainage systems. The introduction of constructed wetlands to treat surface runoff essentially followed a 1997 Environment Agency for England and Wales report advocating the use of “soft engineered” facilities including wetlands in the context of sustainable development and Agenda 21. Subsequently published reports by the UK Construction Industry Research and Information Association (CIRIA) have promoted the potential benefits to both developer and the community of adopting constructed wetlands and other vegetated systems as a sustainable drainage approach. In addition, the UK Environment Agency and Highways Agency (HA) have recently published their own design criteria and requirements for vegetative control and treatment of road runoff. A case study of the design and performance of a constructed wetland system for the treatment of road runoff is discussed. The performance of these systems will be assessed in terms of their design criteria, runoff loadings as well as vegetation and structure maintenance procedures. The differing design approaches in guidance documents published in the UK by the Environment Agency, CIRIA and HA will also be evaluated.

Functions of Macrophytes in Constructed Wetlands

1994 ◽  
Vol 29 (4) ◽  
pp. 71-78 ◽  
Author(s):  
Hans Brix
Keyword(s):  
Constructed Wetlands ◽  
Microbial Growth ◽  
Surface Flow ◽  
Wetland Plant ◽  
Intrinsic Properties ◽  
Treatment Processes ◽  
Flow Systems ◽  
Physical Effects ◽  
Uptake Of Nutrients ◽  
Quantitative Importance

Macrophytes have several intrinsic properties that makes them an indispensable component of constructed wetlands. The most important functions of the macrophytes in relation to the treatment of wastewater are the physical effects brought about by the presence of the plants. The macrophytes stabilise the surface of the beds, provide good conditions for physical filtration, prevent vertical flow systems from clogging, insulate against frost during winter, and provide a huge surface area for attached microbial growth. Contrary to earlier belief, the growth of macrophytes does not increase the hydraulic conductivity of the substrate in soil-based subsurface flow constructed wetlands. The metabolism of the macrophytes affects the treatment processes to different extents depending on the design of the constructed wetland. Plant uptake of nutrients is only of quantitative importance in low-loaded systems (surface flow systems). Macrophyte-mediated transfer of oxygen to the rhizosphere by leakage from roots increases aerobic degradation of organic matter and nitrification. The macrophytes have additional site-specific values by providing habitat for wildlife and making wastewater treatment systems aesthetically pleasing.

scholarly journals Cryptosporidium spp. Infections in Livestock and Wild Animals in Azerbaijan Territory

2020 ◽  
Vol 2 (1) ◽  
pp. 44
Author(s):  
Simuzer Mamedova ◽  
Panagiotis Karanis
Keyword(s):  
Staining Method ◽  
Current Knowledge ◽  
Protozoan Parasite ◽  
Structural Features ◽  
Cryptosporidium Spp ◽  
Faecal Samples ◽  
Cryptosporidium Oocysts ◽  
Stool Specimens ◽  
Intracellular Protozoan Parasite ◽  
Acid Fast Staining

Cryptosporidium is an intracellular protozoan parasite and is increasingly gaining attention as a human and an animal pathogen, mainly due to its predominant involvement in worldwide waterborne outbreaks. This paper reviews the current knowledge and understanding of Cryptosporidium spp. in terrestrial and aquatic animals in Azerbaijan. The diagnosis of cryptosporidiosis relies on the identification of oocysts in faecal samples released by the infected host. Stool specimens were processed using the modified acid-fast staining method (Ziehl-Neelsen) and microscopically examined for Cryptosporidium oocysts. Thirteen species of Cryptosporidium (C. fragile, C. ducismarci, C. serpentis, C. varani, C. baileyi, C. meleagridis, C. muris, C. parvum, C. ubiquitum, C. andersoni, C. bovis, C. hominis, C. suis) from amphibians, reptiles, birds and mammals have been identified as a result of studies conducted between 1987 and 2019 on the structural features of Cryptosporidium oocysts in Azerbaijan territory.

scholarly journals Abundance and Spatial Distribution of Aerobic Anoxygenic Phototrophic Bacteria in Tama River, Japan

Water ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 150
Author(s):  
Yuki Sato-Takabe ◽  
Setsuko Hirose ◽  
Tomoyuki Hori ◽  
Satoshi Hanada
Keyword(s):  
Spatial Distribution ◽  
Phototrophic Bacteria ◽  
Anoxygenic Phototrophic Bacteria ◽  
Epifluorescence Microscopy ◽  
Free Living ◽  
Aerobic Anoxygenic Phototrophic Bacteria ◽  
Riverine Environment ◽  
Global Oceans ◽  
Total Bacteria ◽  
Aggregation Form

Aerobic anoxygenic phototrophic bacteria (AAnPB) are widely distributed and regarded as key players driving the carbon cycle in surface water of global oceans, coastal and estuary areas and in other freshwater environments (e.g., ponds and lakes). However, the abundance and spatial distribution of AAnPB in rivers is much less well-known. Here we investigated the variation of the absolute cell abundances of the total bacteria, AAnPB and cyanobacteria, at four different sites in Tama River, Japan, and the spatial distribution (i.e., free-living or particle-attached existence form) of AAnPB at two out of the four sites using infra-red epifluorescence microscopy. Free-living cell abundances for the total bacteria, AAnPB and cyanobacteria were 1.6–3 × 105, 1.5–4.4 × 104 and <3.2 × 104 cells mL−1, respectively. The free-living AAnPB accounted for 6.1%–19.6% of the total bacterial abundance in the river. The peaks of the AAnPB and cyanobacteria abundances were found at the same site, suggesting that the AAnPB could potentially coexist with cyanobacteria. Meanwhile, the particle-attached AAnPB were observed at the two sites of the river, accounting for 52.2% of the total bacteria abundance in the particle. Our results showed the existence and aggregation form of AAnPB in the riverine environment.

Various dictyostelids from the environment can produce multilamellar bodies

2020 ◽  
Vol 66 (12) ◽  
pp. 679-688
Author(s):  
Alicia F. Durocher ◽  
Cynthia Gagné-Thivierge ◽  
Steve J. Charette
Keyword(s):  
Cell Communication ◽  
Laboratory Strain ◽  
Food Storage ◽  
Epifluorescence Microscopy ◽  
Free Living ◽  
Multicellular Development ◽  
Multilamellar Bodies ◽  
Transmission Electron ◽  
Axenic Conditions ◽  
Social Amoebae

Multilamellar bodies (MLBs), structures composed of concentric membrane layers, are known to be produced by different protozoa, including species of ciliates, free-living amoebae, and Dictyostelium discoideum social amoebae. Initially believed to be metabolic waste, potential roles like cell communication and food storage have been suggested for D. discoideum MLBs, which could be useful for the multicellular development of social amoebae and as a food source. However, among dictyostelids, this phenomenon has only been observed with D. discoideum, and mainly with laboratory strains grown in axenic conditions. It was thought that other social amoebae may also produce MLBs. Four environmental social amoeba isolates were characterized. All strains belong to the Dictyostelium genus, including some likely to be Dictyostelium giganteum. They have distinctive phenotypes comprising their growth rate on Klebsiella aerogenes lawns and the morphology of their fruiting bodies. They all produce MLBs like those produced by a D. discoideum laboratory strain when grown on K. aerogenes lawns, as revealed by analysis using the H36 antibody in epifluorescence microscopy as well as by transmission electron microscopy. Consequently, this study shows that MLBs are produced by various dictyostelid species, which further supports a role for MLBs in the lifestyle of amoebae.

scholarly journals A systematic approach to determine herbicide removals in constructed wetlands using time integrated passive samplers

2011 ◽  
Vol 1 (1) ◽  
pp. 11-17 ◽  
Author(s):  
Declan W. Page ◽  
Stuart J. Khan ◽  
Konrad Miotlinski
Keyword(s):  
Water Treatment ◽  
Constructed Wetlands ◽  
Systematic Approach ◽  
Passive Samplers ◽  
Stormwater Quality ◽  
Natural Wetland ◽  
Process Validation ◽  
Treatment Processes ◽  
Wide Range ◽  
Wetland System

Natural water treatment systems such as wetlands are increasingly being recognised for their role as part of a multi-barrier system for water recycling. Natural wetland systems have the ability to provide effective treatment for a wide range of organic chemicals. However, techniques are required to validate the performance of these treatment processes in the field. This paper provides a new method for evaluating wetland systems using passive samplers and applies a statistical method for use in advanced water treatment processes. Three years of stormwater quality passive sampler data for diuron, simazine and atrazine is provided to determine herbicide removal between the inlet and outlet regions of a constructed wetland. Mean removal rates over the three year period for diuron, simazine and atrazine were 43, 54 and 50% respectively. The results show that this method coupled with passive samplers is amenable to wetland system barrier characterisation where opportunities for process validation is not feasible.

scholarly journals Cryptosporidium Propidium Monoazide-PCR, a Molecular Biology-Based Technique for Genotyping of Viable Cryptosporidium Oocysts

2009 ◽  
Vol 75 (21) ◽  
pp. 6856-6863 ◽  
Author(s):  
Cristin C. Brescia ◽  
Shannon M. Griffin ◽  
Michael W. Ware ◽  
Eunice A. Varughese ◽  
Andrey I. Egorov ◽  
...  
Keyword(s):  
Human Health Risk ◽  
Protozoan Parasite ◽  
Molecular Diagnostic ◽  
Diagnostic Tools ◽  
Pcr Analysis ◽  
Propidium Monoazide ◽  
Pcr Assay ◽  
Severe Diarrhea ◽  
Cryptosporidium Oocysts ◽  
Surface Water Samples

ABSTRACT Cryptosporidium is an important waterborne protozoan parasite that can cause severe diarrhea and death in the immunocompromised. The current methods used to monitor for Cryptosporidium oocysts in water are the microscopy-based USEPA methods 1622 and 1623. These methods assess total levels of oocysts in source waters, but do not determine oocyst viability or genotype. Recently, propidium monoazide (PMA) has been used in conjunction with molecular diagnostic tools to identify species and assess the viability of bacteria. The goal of this study was the development of a Cryptosporidium PMA-PCR (CryptoPMA-PCR) assay that includes PMA treatment prior to PCR analysis in order to prevent the amplification of DNA from dead oocysts. The results demonstrated that PMA penetrates only dead oocysts and blocks amplification of their DNA. The CryptoPMA-PCR assay can also specifically detect live oocysts within a mixed population of live and dead oocysts. More importantly, live oocysts, not dead oocysts, were detected in raw waste or surface water samples spiked with Cryptosporidium oocysts. This proof-of-concept study is the first to demonstrate the use of PMA for pre-PCR treatment of Cryptosporidium oocysts. The CryptoPMA-PCR assay is an attractive approach to specifically detect and genotype viable Cryptosporidium oocysts in the water, which is critical for human health risk assessment.

Sign in / Sign up

Export Citation Format

Share Document