Document Detail

Protozoan predation as a mechanism for the removal of cryptosporidium oocysts from wastewaters in constructed wetlands.
MedLine Citation:
PMID:  11804094     Owner:  NLM     Status:  MEDLINE    
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 10(6) 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.
R Stott; E May; E Matsushita; A Warren
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Water science and technology : a journal of the International Association on Water Pollution Research     Volume:  44     ISSN:  0273-1223     ISO Abbreviation:  Water Sci. Technol.     Publication Date:  2001  
Date Detail:
Created Date:  2002-01-23     Completed Date:  2002-06-25     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9879497     Medline TA:  Water Sci Technol     Country:  England    
Other Details:
Languages:  eng     Pagination:  191-8     Citation Subset:  IM    
Department Civil Engineering, University of Portsmouth, UK.
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MeSH Terms
Biodegradation, Environmental
Cryptosporidium parvum*
Population Dynamics
Predatory Behavior*
Water Purification / methods*

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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