Drinking Water Quality and Health. Engineered Water Systems.
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Transcript of Drinking Water Quality and Health. Engineered Water Systems.
Drinking Water Quality and Health
Engineered Water Systems
Water and Health
• 80% of sickness in the world is caused by inadequate water supply or sanitation
• 40% of the world population does not have access to safe drinking water
• It is estimated that water-borne diseases kill 25,000 people per day
• In many populated areas of the world, water-borne diseases represent the leading cause of death
Drinking Water Regulation in the U.S.
• 1912 – First regulated in U.S. with Public Health Service Act– relied on voluntary and local efforts– dramatic decrease in water-borne
disease over the next 30 years• 1974 – Federal oversight of all public water
supplies with Safe Drinking Water Act (SDWA)
• 1986 – Current framework established with SWDA Amendments
Sizes of Particles in Water
Palatable vs. Potable
• Palatable– aesthetically pleasing– considers the presence of chemicals
that do not pose a threat to human health
– palatability affected by chloride, color, corrosivity, iron, manganese, taste and odor, total dissolved solids, turbidity
Potable Water
• Potable– safe to drink– not necessarily aesthetically pleasing– potability affected by
•microbials (e.g. Giardia, Cryptosporidium)
•organic chemicals (e.g., alachor, chlordane, 1,2-dichloroethylene, disinfection by-products)
• inorganic chemicals (e.g., cadmium, copper, lead, mercury)
•Radio-nuclides
Palatable and Potable
• The goal of municipal water treatment is to provide water that is both palatable and potable
• Palatability and Potability regulated under Safe Drinking Water Act– Palatability: Secondary Maximum
Contaminant Levels (SMCLs)– Potability: Primary Maximum Contaminant
Levels (MCLs) - (for systems serving more than 25 persons per day for greater than 60 days per year)
Primary MCLs (mg/L)
Primary MCLs (mg/L)
Primary MCLs (mg/L)
Primary MCLs (mg/L)
Secondary MCLs (mg/L)
Sources of Drinking Water• Groundwater
– shallow wells– deep wells
• Surface water– rivers– lakes– reservoirs
Ground- vs. Surface Water
Groundwater• constant composition• high mineral content• low turbidity• low color• low or no D.O.• high hardness• high Fe, Mn
Surface water• variable composition• low mineral content• high turbidity• colored• D.O. present• low hardness• taste and odor
Surface Water Treatment
• Primary objectives are to
1. Remove suspended material (turbidity) and color
2. Eliminate pathogenic organisms
• Treatment technologies largely based on coagulation and flocculation
Surface Water Treatment
Surface water from supply
Rapid Mix
FlocculationBasin
Sedimentation
basin
SludgeRapid Sand Filter Disinfection
StorageTo DistributionSystem
Screen
Groundwater Treatment
• Primary objectives are to
1.Remove hardness and other minerals
2.Eliminate pathogenic organisms• Treatment technologies largely based on
precipitation
Groundwater Treatment
Ground waterfrom wells
Sedimentation
basin
SludgeRecarbo-nation
To Distri-butionSystem
Rapid Mix
FlocculationBasin
Disinfection
Storage
CO2