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UNC-Chapel Hill ENVR 890 - Wastewater Reclamation and Reuse

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Wastewater Reclamation and ReuseWastewater Reuse: An Attractive Option for Improved Water Resources ManagementDirect/Directed Potable ReuseWHO Agricultural Reuse of Wastewater and ExcretaHealth Risk Contaminants of Reclaimed WaterHealth Risks and Benefits of Wastewater and Excreta ReuseWHO Health Risk-Based ApproachSummary of Health Risks Associated with the Use of Wastewater in IrrigationRisk Management Points for Agricultural ReuseHuman Exposure Control for WW Agricultural IrrigationSlide 11Slide 12Steps in Agricultural WW Reuse Management: Waste Treatment to Remove or Inactivation of PathogensSteps in Agricultural WW Reuse Management: Crop RestrictionSteps in Agricultural WW Reuse Management Irrigation TechniquesSteps in Agricultural WW Reuse Management Chemotherapy and VaccinationSlide 17Health Risk Basis of California Water Reclamation ProgramLimitations of the California Reuse SystemRisk from One-time Consumption of 100 ml from the St. Petersburg, FL Reclamation Facility (Rose et al., 1996) (assumed all microbes were viable and infectious; worst case)Estimated Risks of Virus Infection/Person/Year for Various Concentrations of E. coli by Use of Untreated or Treated Wastewater in IrrigationManagement Strategies to Reduce Health Risks from Agricultural ReuseWHO Revised Microbiological Guidelines for Treated WW use in AgricultureManagement Strategies - Crop RestrictionManagement Strategies - Waste ApplicationManagement Strategies - Control of Human ExposureWHO Estimates of Log10Pathogen Reduction by Control Measures for Agricultural Reuse of WastewaterExisting Reclaimed Water Standards and Guidelines - Non-Potable ReuseSlide 29Wastewater Reclamation and ReuseMark D. SobseyENVR 890-2Spring 2009Wastewater Reuse: An Attractive Option for Improved Water Resources Management•Why do THIS?•When you can do THIS INSTEAD?• ……Potable use?• Other non-potable uses• Industrial cooling• Irrigation• Beneficial reuse for:• Further treat, then…Direct/Directed Potable Reuse•Singapore, Malta, Israel and Namibia now augment their source drinking water (10-20 %) with reclaimed wastewaterWHO Agricultural Reuse of Wastewater and Excreta•WHO Guidelines focus on agricultural and aquacultural reuse of wastewater•Promote beneficial use•Health risk-based•Considers different exposure groups–Workers (farmers)–Children–Neighbors–Consumers•Employs epidemiological and microbial data for diarrheal disease and ascariasis health risk estimatesHealth Risk Contaminants of Reclaimed Water•Microbiological quality: pathogens•Total mineral content (e.g., TDS)•Heavy metal toxicants•Toxic/biologically active organic compounds–Disinfection by-products–Pharmaceutically active compounds•Antibiotics•Estrogens•Psychotropic compounds•Caffeine•Etc.Health Risks and Benefits of Wastewater and Excreta ReuseDirect Health Effects•Waterborne disease outbreaks; hyperendemic disease•Contributes to background disease rates from helminths and other pathogensIndirect Health Effects•Impacts on water safety for drinking recreation, food preparation•Positive impacts on household food securityDriving Forces•Water Scarcity•Wastewater as a Resource•Population growth, urbanizationWHO Health Risk-Based Approach•Establish tolerable (acceptable) risk•Zero is not achievable in the real world)•A national to local concern•WHO anchors risk level in its international guidelines•Accepted point of reference for carcinogens in drinking water: 1/100,000 lifetime excess risk of cancer•US EPA 1/10000 risk of infection (Giardia)•DALYs: 10-6 DALYS per person per year (WHO)•Considers beneficial use; attempts to make norms not overly stringentSummary of Health Risks Associated with the Use of Wastewater in IrrigationRisk Management Points for Agricultural ReuseHuman Exposure Control for WW Agricultural IrrigationFour groups of people are at potential risk:• Agricultural field workers and their families• Crop handlers• Consumers (of crops, meat and milk)• Those living near the affected fieldsHuman Exposure Control for WW Agricultural Irrigation•Agricultural field workers are at high risk of parasitic infections. •Exposure to hookworm infection can be reduced, even eliminated, by the use of less contaminating irrigation methods and by the use of appropriate protective clothing (i.e. shoes for field workers and gloves for crop handlers). •A rigorous health education program that targets consumers, farm workers, produce handlers and vendors is needed. •Handwashing with soap is an important behavior that needs to be emphasized. –Handwashing with soap reduces diarrheal disease transmission by 30-40%•Field workers should be provided with adequate sanitation facilities and safe water for drinking and hygiene purposes to avoid the consumption of, and contact with, wastewater.Human Exposure Control for WW Agricultural Irrigation•Sanitation facilities and safe water should be provided at markets for washing and ‘‘freshening’’ produce. –Vendors need to practice good personal and food hygiene. •Consumers can cook vegetables, meat and milk, and practice good personal and domestic hygiene to protect their health. •Meat should be inspected and carcasses infected with tapeworm larvae should be rejectedSteps in Agricultural WW Reuse Management: Waste Treatment to Remove or Inactivation of Pathogens•Conventional wastewater treatment options (primary and secondary treatments) are effective at removing/inactivating pathogens•These processes may be difficult and costly to operate properly in developing world situations. •Waste stabilization ponds (WSP), properly designed and operated properly, are effective at reducing pathogens–They can be operated at low cost where inexpensive land is available•A series of shallow ponds linked together maximizes retention time •WSPs should be designed, operated and maintained in such a way as to prevent disease vectors from breeding in the ponds.Steps in Agricultural WW Reuse Management: Crop Restriction•Water of poorer quality can be used to irrigate:–Non-vegetable crops such as cotton–Crops that will be cooked before consumption (e.g. potatoes)•Crop restriction may protect the health of consumers but not farm workers and their families. •Crop restriction is not an adequate single control measure•It should be considered within an integrated system of control•In Chile the use of crop


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UNC-Chapel Hill ENVR 890 - Wastewater Reclamation and Reuse

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