Transcript Slide 1
Pathogens & Contaminants
Pathogens & Contaminants
Corinne Waelti, seecon international gmbh
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Pathogens & Contaminants
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Contents
1. Introduction 2. Characteristics of Pathogens and Contaminants 3. Pathogens 4. Contaminants 5. References Pathogens & Contaminants 3
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1. Introduction
The overall Problem
Substances such as pathogens (microorganisms) and contaminants (chemicals and metals) in drinking water may harm both public health and the environment. In developing countries, the contamination of drinking water with pathogens is the major factor for prevalence of diseases. Most often, faeces infiltrating drinking water sources are responsible for contamination with pathogens. Contaminants in drinking water may originate from human activities and natural processes.
Pathogens & Contaminants 4
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2. Characteristics of Pathogens and Contaminants
Types of Pathogens and Contaminants
Pathogens Contaminants
•
Bacteria
• e.g. Salmonella, Escherichia coli, Campylobacter •
Viruses
• e.g. Rotavirus, Hepatitis •
Parasitic protozoa
• e.g. Giardia •
Helminths (worms)
• e.g. Trichuris trichiura
Microorganisms
Pathogens & Contaminants • • •
Inorganic chemicals
• e.g. nitrate, arsenic, fluoride, chloride
Organic chemicals
• e.g. petro-chemicals (oil, diesel), solvents, drugs, pesticides
(Heavy) metals
• e.g. cadmium, copper, lead, mercury 5
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2. Characteristics of Pathogens and Contaminants
Sources of Pathogens and Contaminants
• • • • • • Underground storage tanks Chemical storage Accidental spills of hazardous materials Spreading of sewage treatment sludge Septic systems Animal feedlots • • • • •
Source: BUCHANAN et al. (2010)
Storage and spreading of road salt Underground pipelines or sewers Use and spilling of fertilisers and pesticides Landfills Private and abandoned wells
Source: CONSERVATION ONTARIO (2009)
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2. Characteristics of Pathogens and Contaminants
Dispersion of Pathogens and Contaminants
Migration of contaminants in an unconfined (left) and a confined (right) aquifer. Movement of insoluble contaminants in ground water: Oil spills (lighter than water) accumulate on the water table and spread horizontally.
Source: WAL (2010)
Pathogens & Contaminants
Adapted from FREEZE et al. (n.y.)
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2. Characteristics of Pathogens and Contaminants
General Effects of Pathogens and Contaminants
Drinking water contamination: • Poor drinking water quality • Loss of community’s drinking water supplies • High costs for restoration and alternative drinking water supplies • Health problems • •
Examples for related economic effects:
Higher health expenses Restricted work force •
Impacts on the environmental system by contaminants:
Loss of ecosystem functions • •
Examples for related economic effects:
Less revenue by fisheries Less revenue from tourism Pathogens & Contaminants 8
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3. Pathogens
Transmission & Health Risks of Disease
• • • • • Faecal-oral transmission routes: Fingers Flies and other insects Fields (agriculture) Food Fluids
Health risks:
Gastrointestinal symptoms such as diarrhoea, vomiting and stomach cramps
Source: HESPERIAN & UNDP (2004)
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3. Pathogens
Probability of Causing Infections
Persistence in the environment Low minimal infective doses Little or no human immunity Long latency periods Pathogens & Contaminants Amount and variability of pathogens
SHUVAL et al. (1986)
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3. Pathogens
Probability of Causing Infections
Persistence in the environment Low minimal infective doses Little or no human immunity Long latency periods Sanitation system
Source: /s_6 http://2.bp.blogspot.com/ 2yIT8xt_stM/TwtB4J9sBqI/AAAAAAAACmY 9HHksUA/s1600/Istanbul%20Toilet.gif
[Accessed: 05.06.2012]
Amount and variability of pathogens
SHUVAL et al. (1986)
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4. Contaminants
Health Risks related to contaminated Groundwater
• • • •
Possible health risks:
Cancer Liver, kidney and nerve problems Birth defects Learning disabilities in children
Source: WALLIN (1997) Source: http://www.thewaterchannel.tv/tutorial/s ection_4/6.html
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5. References
BUCHANAN, B., DE LA CRUZ, N, MACPHERSON, J., WILLIAMSON, K. (2010): Water Wells that Last for Generations. Edmonton: Alberta Agriculture and Rural Development. URL: http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/wwg404 [Accessed: 05.06.2012].
CONSERVATION ONTARIO (Editor) (2009): Wellhead Protection Areas. Newmarket: Conservation Ontario. URL: www.conservationontario.ca/source_protection/files/ODWSP%202009%20Finals/ODWSP_FAQS_wellhead_EN_2009_02_27_WEB.pdf [Accessed: 06.06.2012].
FREEZE, R.A., ATWATER, J., LIEBSCHER, H. (n.y.): Water Stewardship . Ground Water Resources of British Colombia. Victoria: The Province of British Columbia. URL: http://www.env.gov.bc.ca/wsd/plan_protect_sustain/groundwater/gwbc/C05_contamination.html
[Accessed: 05.06.2012].
HESPERIAN FOUNDATION (Editor); UNDP (Editor) (2004): Sanitation and Cleanliness for a Healthy Environment. Berkeley: The Hesperian Foundation. URL: www.unwater.org/downloads/EHB_Sanitation_EN_lowres.pdf
[Accessed: 05.06.2012].
SHUVAL H.I., ADIN, A., FATTAL, B., RAWITZ, E., YEKUTIEL, P. (1986): Wastewater Irrigation in Developing Countries. Health Effects and Technical Solutions. Washington, D.C.: The World Bank. URL: http://documents.worldbank.org/curated/en/1986/05/440564/integrated-resource-recovery-wastewater-irrigation-developing countries-health-effects-technical-solutions [Accessed: 05.06.2012].
WAL, A. van der (2010): Understanding Groundwater & Wells in Manual Drilling. Instruction Handbook for Manual Drilling Teams on Hydro-geology for Well Drilling, Well Installation and Well Development. Papendrecht: Practica Foundation. URL: www.unicef.org/wash/files/04.pdf
[Accessed: 06.06.2012].
WALLIN, R. (1997): Wellhead Protection: A Guide for Arizona Communities. TUCSON: Arizona Department of Environmental Quality, Water Quality Division. URL: http://www.unicef.org/wash/files/04.pdf
[Accessed: 05.06.2012].
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