water and wastewater water quality laws water treatment wastewater treatment
Post on 26-Dec-2015
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Water and Wastewater
• Water Quality Laws
• Water Treatment
• Wastewater Treatment
Clean Water Act
• Goal is to “restore the chemical, physical and biological integrity of the nation’s waters”
• Requires reduction of pollutants entering all surface water
• Strict requirements for wastewater treatment plants
• Control of non-point source pollution
• Tighter controls on toxic pollutants
• In 1948 Congress passed a bill to provide federal funds for constructing wastewater treatment facilities
• The 1972 amendments made significant changes
• Mandated that by 1983 the nation’s waterways should be fishable and swimmable
• By 1995 discharges to waterways should be eliminated
• Standards defining the levels of pollutants acceptable for discharge were called effluent limitations
• These were used when issuing National Pollution Discharge Elimination System, NPDES, permits
• In 1989 there were 50,000 industrial and 16,000 municipal facilities that had NPDES permits
• SPDES permits are temporary discharge permits issued for short-term occurrences
• Enforcement actions, including criminal action, are taken for noncompliance
• The CWA provides for the EPA in conjunction with the Army Corp of Engineers to protect wetlands by limiting the discharge of dredged or fill material into surface waters
• Estuaries are protected from activities such as landfilling, sewage outflow and industrial wastewater discharge
Safe Drinking Water Act
• Written in 1974, amended in 1986
• Protects drinking water resources
• Requires adherence to established drinking water standards
• Protects underground sources including a wellhead protection program
Basic Required Activities
• Establish and enforce Maximum Contaminant Levels MCL’s
• Monitoring of contaminants• Filtration of water from surface water
sources• Regulation of the use of lead materials in
public water supply systems• Wellhead protection
National Drinking Water Regulations
• Found in 40 CFR
• Primary drinking water standard affecting public health
• Secondary standards affect aesthetic qualities of public drinking water
Maximum Contaminant Levels
• Based on an assumed human consumption of 2 liters per day
• If monitoring for a contaminant is not feasible then treatment techniques must insure compliance
• Primary MCLs– Arsenic
– Barium
– Chromium
– Cadmium
– Lead
– Mercury
– Nitrate
– Selenium
Maximum Contaminant Level Goals MCLGs
• Not enforceable health goals
• The Reference Dose, RfD, is the amount of chemical a person can be exposed to without any adverse health effects
• It is obtained from the NOAEL which is divided by an uncertainty factor
• For carcinogens the MCLG is set at zero
Marine Protection, Research, and Sanctuaries Act (Title I)
• Requires permits for ocean dumping which may limit the sites and times that dumping occurs
• Radiological, chemical and biological warfare agents and radioactive wastes are prohibited from being dumped
• The Army Corp of Engineers is responsible for permitting of dredged materials
• The Coast Guard monitors activities
• The EPA assesses penalties for violations
• Sewage sludge, ash & solid waste dumping has not lessened over the years
• It has been moved further off shore
• Persistence of plastics disposed at sea continues to be a threat to wildlife
Water Treatment (for Drinking Water)
• A water supply is evaluated on it’s quality, quantity and proximity to where it is needed
• A water supply system includes (Figure 7-7): – supply source– storage facility– treatment facility – transmission lines– final distribution facilities
• Treatment plants generally remove disease causing microorganisms, trace organic compounds, suspended solids, minerals causing hardness, and substances causing disagreeable color, taste and odor.
• Consumptive use in the US is about 22 %
• This means that the majority of the water supplied ends up as waste water
• The average American uses more than 180 gallons a day
Waterborne Disease
• Typhoid• Dysentery• Cholera• Infectious hepatitis• Amoebic dysentery• Giardiasis• Gastroenteritis• Cryptosporidiosis
Chemical Contaminants
• Minerals dissolved from rocks and soil
• Pesticides and herbicides
• Leaking underground storage tanks
• Industrial effluents
• Seepage from septic systems
• Wastewater treatment plants
• Landfills
• The water itself may be corrosive, leaching lead into the water supply
• The water treatment process itself may introduce trihalomethanes, a by-product of the reaction of chlorine with organic materials and other chemical contaminants
• Water may be treated to improve its color, odor and taste
• Iron and manganese may be removed to prevent staining of clothes and plumbing fixtures
• Fluoride is added to improve dental health
Physical Treatment(for Drinking Water)
• Does not produce a new substance
• Types of Treatment– Screening– Adsorption– Aeration– Flocculation (when coagulants used)– Sedimentation– Filtration (including membranes)
Chemical Treatment(for Drinking Water)
• Results in the formation of new chemical substances
• Type of Treatment– Coagulation (for better filtration)– Disinfection (fig. 7-15)– Water softening (ion exchange for Na)– Oxidation (via aeration or ozone)
Biological Treatment(for Drinking Water)
• Use living organisms to bring about chemical change
Waste Water Treatment
• Individual Systems – Septic Systems
• Public/Municipal Treatment Systems– Primary Treatment– Secondary Treatment– Tertiary Treatment
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