Transcript Document 7277801

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
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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):
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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
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Typhoid
Dysentery
Cholera
Infectious hepatitis
Amoebic dysentery
Giardiasis
Gastroenteritis
Cryptosporidiosis
Chemical Contaminants
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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
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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
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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