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Cryptosporidiosis Cryptosporidiosis is a parasitic infection caused by Cryptosporidium, a protozoan parasite, and spreads via the faecal-oral route. In humans without an intact immune system, it can provoke not only temporary, but permanent and lifethreatening diarrhoea. Although the infection was identified only 30 years ago, it is a common waterborne disease found worldwide. (strained) by the fine sediments that constitute riverbeds and the matrix of heterogeneous aquifers. In this particular case, while other drinking water treatment techniques fail, implementing RBF is able to effectively control the risk of oocysts reaching drinking water. sedimentation analyses RIVERBANK FILTRATION NETWORK (RBFN) Removal of pathogenic microorganisms by bank filtration sieve analyses 100 Grainsize < d [% mass of total dry mass] Cryptosporidium oocysts are present in high concentrations in untreated as well as treated sewage. For instance, one infected cattle can excrete up to 1010 oocysts per day. Hence, the micro-organisms are commonly found in open water bodies. 90 80 70 size range of Cryptosporidium oocysts 60 50 40 30 20 10 0 0,001 0,01 0,1 1 Grainsize d in mm New Supply Channel River Ganga (barrage reservoir) Sizes of grains versus size of oocysts (Sandhu, 2007) A collaborative initiative of University of Applied Sciences Dresden (HTWD), Dresden University of Technology (TUD), DVGW - Water Technology Center Dresden (DVGW-TZW), Stadtwerke Duesseldorf AG (SWD), Uttarakhand Jal Sansthan (UJS), Indian Institute of Technology Roorkee (IITR). For more information River Ganga at Varanasi (Sandhu, 2006) Cryptosporidium oocysts are particularly of concern due to their high infectivity (consumption of only 10 oocysts can cause illness), longevity (weeks to months survival in fresh water) and resistance to conventional drinking water disinfection methods such as chlorination (WHO). As Cryptosporidium oocysts are relatively large in size (4 - 14 µm, i.e. larger than bacteria and viruses), they can very effectively be filtered The Coordinator Cooperation Centre for Riverbank Filtration (CCRBF) C/O Maintenance Division, Uttarakhand Jal Sansthan Pant Dweep, Haridwar 249 401 (Uttarakhand), INDIA Ph./Fax: 01334-262011 Email: [email protected] Mr. Cornelius Sandhu University of Applied Sciences Dresden Department of Civil Engineering & Architecture Division of Water Sciences - Riverbank Filtration Network Friedrich-List-Platz 1, D-01069 Dresden, GERMANY Ph.: +49-351-4622681, Fax: +49-351-4622195 Email: [email protected] This publication is prepared by C. Sandhu, C. Syhre and T. Grischek, University of Applied Sciences Dresden, Germany. Funded by the German Federal Ministry of Education and Research (BMBF) programme ‘India and Germany – Strategic Partners for Innovation’. Introduction Spread of waterborne diseases Though the coverage of drinking water in India has increased, 17 % of the Indian population still does not have adequate access to drinking water. It is still a common mode to dispose sewage without treatment into rivers. Additionally, animal faeces – containing pathogens – from agricultural lands and roaming animals are introduced into water bodies. Worldwide over 1.1 billion people lack adequate water supplies (safe and affordable drinking water) and about 2.6 billion people lack improved sanitation. Waterborne diseases cause approximately 1.8 million deaths each year at a global scale (WHO/UNICEF, 2006). Bacteria Waterborne disease HUS, gastroenteritis, Typhoid, gastroenteritis Dysentery Cholera Leptospirosis Gastroenteritis Gastroenteritis Pathogens Enterotoxygenic E. coli Salmonella ssp. Shigella ssp. Vibrio cholerae Leptospira interrogans Yersinia enterocolitica Campylobacter jejuni Poliomyelitis Gastroenteritis Jaundice, liver failure Gastroenteritis Viruses Poliovirus Rotaviruses Hepatitus A virus Norwalk virus Giardiasis Cryptosporidiosis Amoebic dysentery Protozoa Giardia lamblia Cryptosporidium parvum Entamoeba histolytica Riverbank filtration (RBF) offers a simple and effective means to remove disease-causing microorganisms from the water, and for this reason has been implemented in Europe for over 100 years. Applied as alternative to direct surface water abstraction in India, it reduces the risk of waterborne diseases. sewage manured fields cattle Pathogen removal processes during RBF (Syhre, 2007) human and animal feces Riverbank Improved Sufficient water c o n t asanitation m i n a t e for d hygiene filtration drinking water flies = barriers hands mouth Barriers to the faecal-oral route (Syhre, 2007) If river water is directly, and without sufficient treatment, used as the source for drinking water, there is no barrier for the transmission of waterborne diseases. RBF can form such a barrier. Microbial analyses of riverbank filtrate from abstraction wells on the River Rhine (Germany) demonstrated a 99.9 % (3 log) removal of coliform bacteria and the complete elimination of Giardia and Cryptosporidium oocysts. On the Upper Ganga Canal in Haridwar (India), a reduction of the total coliform count by more than 99 % (> 2 log) in the riverbank filtrate was determined by the RBFN in 2006. Microorganism Removal of pathogens by RBF During underground passage pathogens are removed due to the interaction of various processes: straining (physical filtration), adsorption to biofilms and aquifer material, grazing by other micro-organisms, being trapped in immobile pore water and natural decay. Especially the clogging layer plays a significant role in limiting the transport of pathogens from the river to the drinking water production well. Log removal ≥ 5.0 Coliform bacteria ≥ 4.8 2.15 2.35 ≥ 2.6 Enteroviruses 1.7 RBF location Reference River Rhine (Remmerden, NL) Missouri River (Parkville, USA) North Platte River (Casper, USA) Havelaar et al., 1995 Weiss et al., 2005 Gollnitz et al., 2005 River Rhine (Remmerden, NL) River Meuse, (Roosteren, NL) Havelaar et al., 1995 Medema et al., 2000 Due to its efficiency in improving source water quality, RBF can serve either as a pre-treatment step or even as final treatment step before disinfection.