Removal and fate of Cryptosporidium parvum, Clostridium perfringens and small-sized centric diatoms (Stephanodiscus hantzschii) in slow sand filters.

The decimal elimination capacity (DEC) of slow sand filtration (SSF) for Cryptosporidium parvum was assessed to enable quantitative microbial risk analysis of a drinking water production plant. A mature pilot plant filter of 2.56m(2) was loaded with C. parvum oocysts and two other persistent organisms as potential surrogates; spores of Clostridium perfringens (SCP) and the small-sized (4-7microm) centric diatom (SSCD) Stephanodiscus hantzschii. Highly persistent micro-organisms that are retained in slow sand filters are expected to accumulate and eventually break through the filter bed. To investigate this phenomenon, a dosing period of 100 days was applied with an extended filtrate monitoring period of 150 days using large-volume sampling. Based on the breakthrough curves the DEC of the filter bed for oocysts was high and calculated to be 4.7log. During the extended filtrate monitoring period the spatial distribution of the retained organisms in the filter bed was determined. These data showed little risk of accumulation of oocysts in mature filters most likely due to predation by zooplankton. The DEC for the two surrogates, SCP and SSCD, was 3.6 and 1.8log, respectively. On basis of differences in transport behaviour, but mainly because of the high persistence compared to the persistence of oocysts, it was concluded that both spores of sulphite-reducing clostridia (incl. SCP) and SSCD are unsuited for use as surrogates for oocyst removal by slow sand filters. Further research is necessary to elucidate the role of predation in Cryptosporidium removal and the fate of consumed oocysts.

[1]  Mark W. LeChevallier,et al.  Water Treatment and Pathogen Control: Process Efficiency in Achieving Safe Drinking-Water , 2004 .

[2]  Peter F. Schuler,et al.  Slow sand and diatomaceous earth filtration of cysts and other particulates , 1991 .

[3]  Jerry E. Ongerth,et al.  Removing Giardia and Cryptosporidium by Slow Sand Filtration , 1993 .

[4]  P. Payment,et al.  Clostridium perfringens and somatic coliphages as indicators of the efficiency of drinking water treatment for viruses and protozoan cysts , 1993, Applied and environmental microbiology.

[5]  J. Herzig,et al.  Flow of Suspensions through Porous Media—Application to Deep Filtration , 1970 .

[6]  J. Rose,et al.  Validity of the Indicator Organism Paradigm for Pathogen Reduction in Reclaimed Water and Public Health Protection , 2005, Applied and Environmental Microbiology.

[7]  Stephane Mazoua,et al.  Aerobic spore-forming bacteria for assessing quality of drinking water produced from surface water. , 2005, Water research.

[8]  Water reuse for irrigation from waste water treatment plants with seasonal varied operation modes. , 2004, Water science and technology : a journal of the International Association on Water Pollution Research.

[9]  Nathalie Tufenkji,et al.  Spatial distributions of Cryptosporidium oocysts in porous media: evidence for dual mode deposition. , 2005, Environmental science & technology.

[10]  A. Warren,et al.  Predation of Cryptosporidium oocysts by protozoa and rotifers: implications for water quality and public health. , 2003, Water science and technology : a journal of the International Association on Water Pollution Research.

[11]  M. Hutchison,et al.  Fate of Pathogens Present in Livestock Wastes Spread onto Fescue Plots , 2005, Applied and Environmental Microbiology.

[12]  S. Hassanizadeh,et al.  Bacteriophages and Clostridium spores as indicator organisms for removal of pathogens by passage through saturated dune sand. , 2003, Water research.

[13]  D. Kooij,et al.  Enumeration of faecal indicator bacteria in large water volumes using on site membrane filtration to assess water treatment efficiency (AGGREGATION CH 3) , 2000 .

[14]  N. Ashbolt,et al.  Environmental inactivation of Cryptosporidium oocysts in catchment soils , 2005, Journal of applied microbiology.

[15]  Nathalie Tufenkji,et al.  Correlation equation for predicting single-collector efficiency in physicochemical filtration in saturated porous media. , 2004, Environmental science & technology.

[16]  S. Yates,et al.  Modeling colloid attachment, straining, and exclusion in saturated porous media. , 2003, Environmental science & technology.

[17]  A C Buck,et al.  An outbreak of waterborne cryptosporidiosis in Swindon and Oxfordshire , 1991, Epidemiology and Infection.

[18]  Charles F. Brush,et al.  Influence of Pretreatment and Experimental Conditions on Electrophoretic Mobility and Hydrophobicity of Cryptosporidium parvum Oocysts , 1998, Applied and Environmental Microbiology.

[19]  M. Sobsey,et al.  Concentration and Detection of Cryptosporidium Oocysts in Surface Water Samples by Method 1622 Using Ultrafiltration and Capsule Filtration , 2001, Applied and Environmental Microbiology.

[20]  P. Gerhardt,et al.  Wet and dry bacterial spore densities determined by buoyant sedimentation , 1982, Applied and environmental microbiology.

[21]  Han-Seung Kim,et al.  Algae as surrogate indices for the removal of Cryptosporidium oocysts by direct filtration , 2002 .

[22]  J. Schijven,et al.  Elimination of viruses, bacteria and protozoan oocysts by slow sand filtration. , 2004, Water science and technology : a journal of the International Association on Water Pollution Research.

[23]  C. Drummond,et al.  Multi-scale Cryptosporidium/sand interactions in water treatment. , 2006, Water research.

[24]  Charles R. O'Melia,et al.  Water and waste water filtration. Concepts and applications , 1971 .

[25]  J. P. Davis,et al.  A massive outbreak in Milwaukee of cryptosporidium infection transmitted through the public water supply. , 1994, The New England journal of medicine.

[26]  Katrina J. Charles,et al.  Transport of MS2 Phage, Escherichia coli, Clostridium perfringens, Cryptosporidium parvum and Giardia intestinalis in a Gravel and a Sandy Soil • , 2005 .

[27]  G. Jaworski,et al.  Zoospore ultrastructure of Zygorhizidium affluens and Z. planktonicum, two chytrids parasitizing the diatom Asterionella formosa , 1988 .

[28]  R. Harvey,et al.  Transport behavior of groundwater protozoa and protozoan-sized microspheres in sandy aquifer sediments , 1995, Applied and environmental microbiology.

[29]  S. Bradford,et al.  Straining, attachment, and detachment of cryptosporidium oocysts in saturated porous media. , 2005, Journal of environmental quality.

[30]  P. Teunis,et al.  Sedimentation of Free and AttachedCryptosporidium Oocysts and Giardia Cysts in Water , 1998, Applied and Environmental Microbiology.

[31]  P J Nobel,et al.  Quantitative risk assessment of Cryptosporidium in surface water treatment. , 2003, Water science and technology : a journal of the International Association on Water Pollution Research.

[32]  Edward J. Bouwer,et al.  Reversibility and mechanism of bacterial adhesion , 1995 .

[33]  T. Harter,et al.  Colloid Transport and Filtration of Cryptosporidium parvum in Sandy Soils and Aquifer Sediments , 2000 .

[34]  R. Cole,et al.  Rotifers Ingest Oocysts of Cryptosporidium parvum , 2000, The Journal of eukaryotic microbiology.

[35]  Y. Park,et al.  Molecular typing and epidemiological survey of prevalence of Clostridium perfringens types by multiplex PCR , 1997, Journal of clinical microbiology.

[36]  Mark T. Anderson.  Improved Method for Separating Zooplankton from Detritus , 1981 .

[37]  A. Warren,et al.  Protozoan predation as a mechanism for the removal of cryptosporidium oocysts from wastewaters in constructed wetlands. , 2001, Water science and technology : a journal of the International Association on Water Pollution Research.

[38]  Nicholas J. Ashbolt,et al.  Fate and Transport of Surface Water Pathogens in Watersheds , 2003 .

[39]  W. Hijnen,et al.  Spores of sulphite-reducing clostridia (SSRC) as surrogate for verification of the inactivation capacity of full-scale ozonation for Cryptosporidium , 2002 .

[40]  A. Magic-Knezev,et al.  Optimisation and significance of ATP analysis for measuring active biomass in granular activated carbon filters used in water treatment. , 2004, Water research.

[41]  C. Saint,et al.  Environmental Temperature Controls Cryptosporidium Oocyst Metabolic Rate and Associated Retention of Infectivity , 2005, Applied and Environmental Microbiology.

[42]  David W. Hendricks,et al.  Removing Giardia Cysts With Slow Sand Filtration , 1985 .

[43]  M. Elimelech,et al.  Transport of Cryptosporidium oocysts in porous media: role of straining and physicochemical filtration. , 2004, Environmental science & technology.

[44]  C N Haas,et al.  Estimation of risk due to low doses of microorganisms: a comparison of alternative methodologies. , 1983, American journal of epidemiology.

[45]  Monroe L. Weber-Shirk,et al.  Biological mechanisms in slow sand filters , 1997 .

[46]  Malte Hermansson,et al.  Characterisation of the behaviour of particles in biofilters for pre-treatment of drinking water. , 2005, Water research.

[47]  R. Hozalski,et al.  Evaluation of microspheres as surrogates for Cryptosporidium parvum oocysts in filtration experiments. , 2003, Environmental science & technology.