Water Pollution Chapter 19

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Water PollutionChapter 19
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Types and Effects

• Water pollution any chemical, biological or
  physical change in water quality that has a
  harmful effect on living organisms or makes water
  unsuitable for use.
• Table 19-1 Major Categories of Water Pollutants

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How do we measure Water Quality?

• 1) Measure number of coliform bacteria present in
  100-mL sample
• WHO recommends 0 colonies/100mL drinking
• EPA max level of swimming 200 colonies/100mL
• 2) Measure oxygen demanding waste
• Determined by measuring biological oxygen demand
  (BOD) the amount of dissolved O needed by
  decomposers to breakdown waste

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Sources

• Nonpoint cant be traced to any single site of
  discharge
• Acid deposit, runoff of chemicals, pesticides,
  fertilizer/manure
• Point source discharge at specific locations
• Factories, sewage treatment, mines, oil tankers
• Easy to identify, monitor and regulate

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Pollution of Freshwater Streams

• Can recover rapidly from degradable,
  oxygen-demanding wastes and excess heat through
  dilution and bacterial decay
• These processes do not eliminate nonbiodegradable
  or slowly degradable
• The time and distance needed to recover depend on
  volume of waste, streams volume, flow rate,
  temp., and pH level.

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Cuyahoga River, Ohio 1959/69
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Pollution of Freshwater Lakes

• Dilution of pollutants in lakes, reservoirs and
  ponds less effective
• Contain stratified layers with little vertical
  mixing
• Little free flow
• Ponds have small volumes of water
• More vulnerable to contamination by plant
  nutrients, oil, pesticides, toxic substances

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Eutrophication

• Lakes receive inputs of nutrients and silt eroded
  and running off from surroundings
• Eutrophication natural nutrient enrichment of
  lakes
• Near urban or agricultural areas, human
  activities accelerate input of plant nutrients
• Results in cultural eutrophication
• Caused mostly by nitrate and phosphate containing
  effluents

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Groundwater Pollution

• More of a problem because numerous sources as we
  dump wastes into storage lagoons, septic tanks,
  landfills, hazardous dumps and deep injection
  wells.
• Human health risks from contaminants
• petrochemicals (gas, oil)
• organic solvents (TCE)
• pesticides and arsenic
• lead (Pb) and fluoride (F-)

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Protecting Groundwater

• Contaminated aquifers almost impossible to clean
  up because of large volume, inaccessibility, and
  slow movement
• Preventing contamination only effective method
• Monitor aquifer near landfills and tanks
• Leak detection systems on underground tanks
• Banning/ strictly regulating hazardous waste

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19.5 Oceans and pollution
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Clean Water Act (1972)

• 1) Make all waters fishable and swimmable
• 2) Require discharge permits of major polluters
• 3) Identify toxic pollutants and require use of
  best practices technology (BPT)

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19-5 Ocean Pollution

• Oceans can dilute, disperse, and degrade large
  amounts of raw sewage, sludge, oil and some
  degradable industrial waste.
• Pro dumping sludge and hazardous waste into deep
  ocean because some organisms are more resilient
  in the ocean.
• Con Feel it would delay pollution prevention and
  promote further degradation of this vital system.

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Coastal Areas

• Include wetlands, estuaries, coral reefs and
  mangrove swamps
• Sustain most of the damage of waste inputs
• Most coastal developing countries dump sewage
  into the sea without treatment
• 85 of sewage from cities along Mediterranean Sea
  is discharged untreated

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Harmful Alga Blooms

• Runoff of sewage and agricultural wastes into
  coastal waters introduce large quantities of
  nitrates (NO3-) and phosphate (PO43-) plant
  nutrients that cause explosive growth of algae.
• The harmful alga blooms (HAB) are called red,
  brown, or green tides depending on their color.
• HABs can release toxins that damage fisheries,
  kill fish-eating birds, reduce tourism and poison
  seafood.

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• Death of the HABs deplete dissolved oxygen and
  cause the death of marine species.
• These oxygen-depleted zones form in coastal
  waters b/c of excessive nonpoint inputs of
  fertilizers and animal wastes from land runoff
  and deposition of nitrogen from the atmosphere.
• In these zones, aquatic life dies or moves
  elsewhere
• Biggest zone in U.S. waters forms every summer in
  Gulf of Mexico near Louisiana and Mississippi
  River Basin (Figure 19-13).

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What pollutants do we dump into the Ocean?

• Barges and ships still legally dump large
  quantities of dredge spoils (materials containing
  toxic metals scraped from bottom of harbors and
  rivers to maintain shipping channels) into
  Atlantic, Pacific, and Gulf coast
• Many countries dump sewage sludge gooey mixture
  of toxic chemicals, infectious agents, solids
  from wastewater treatment plants
• 1992 U.S. banned this practice

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Oil Effects on Animals

• Depend on type of oil, amount released, distance
  from shore, time of year, weather, water
  temperature and currents.
• Volatile hydrocarbons immediately kill organisms,
  some others form globules that float on surface
  and coat feathers of birds.
• This oil coating destroys the natural insulation
  and buoyancy, causing many to drown or die from
  loss of body heat
• Most life forms recover from crude oil within 3
  years, but refined oil recovery up to 10 years

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Oil Effects on Oceans

• Tanker accidents or offshore drilling blowouts
  get publicity but are not the main source of oil
  pollution.
• Largest input of oil is released into the ocean
  during normal operation of offshore wells,
  washing tankers and releasing oily water and from
  pipeline and storage tank leaks.
• Almost half of oil in the ocean is waste oil
  dumped, spilled or leaked into sewers by cities,
  industries or at-home oil changes.

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Clean Up Oil Spills

• Prevention still best method
• Others remove only part of the oil
• None work well on large spill
• Chemical methods
• Coagulating agents to cause oil to clump or sink
• Dispersing agents to break up oil slicks
• Mechanical methods
• Floating blooms to contain the oil spill or keep
  it from moving
• Skimmer boats to vacuum up oil
• Absorbent pads or mesh pillows to soak up oil

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Bioremediation

• Biological method of cleanup
• May involve constructing wetlands or involving
  plants to soak up organic nutrients
• Ex Exxon Valdez oil spill
• Using bacteria to digest the oil coating
• More effective than artificial methods

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19-7 Drinking Water Quality

• If no access to clean water, it is taken from
• Shallow groundwater easily contaminated
• Nearby polluted river water
• Mudholes used by animals and humans
• Purification developing countries with no
  treatment systems
• Tropical regions expose water to the sun
• Bangladesh cloth to strain water
• PUR packet powdered mixture that removes
  pathogenic microorganisms and suspended matter

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• U.S. Safe Drinking Water Act of 1974
• Requires EPA to establish national drinking water
  standards called maximum contaminant levels
• Privately owned wells not required to meet
  standards
• Opposition Congress pressured by
  water-polluting industries to weaken Act
• Eliminate national water tests
• No media access of health violations
• Allow states to violate the act if they cannot
  afford to comply
• Eliminate water systems use of technology to
  remove cancer causing agents

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19.6Preventing/Reducing Surface Water pollution
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Preventing/Reducing Surface Water Pollution

• Clean Up of Nonpoint Pollution
• Reducing and controlling runoff
• Preserve wetlands to allow nitrate and phosphate
  to flow through and be absorbed
• Clean Up of Point Source Pollution
• Legal Approach (Basis of efforts to control
  pollution)
• Federal Water Pollution Control Act of 1972
  (renamed Clean Water Act when amended in 1977)
• 1987 Water Quality Act
• Technological Approach

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Technological Approach to Point source Pollution

• Septic Tanks sewage from each house goes into
  holding tank on property
• (25 of all homes)
• Sewer lines urban areas waste flow through
  series of pipes leading to treatment center
• Some cities have separate lines for sewage and
  storm water some combined lines so if rains
  flood system, often discharges untreated sewage
  into surface water

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Sewage Reaches Treatment Plant

• Preliminary large objects screened
• Primary Treatment (mechanical process)
• Removes 60 of the suspended solids and 30 of
  oxygen demanding wastes from sewage
• Grease and oils removed, organic solids sent to
  Biosolids treatment
• Uses screens to filter out debris such as sticks,
  stones and rags
• Allow suspended solids to settle out as sludge in
  settling tank

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• 2) Secondary Treatment (biological process)
• Aeration process (add oxygen)
• 1) Aerobic bacteria remove 90 of biodegradable,
  oxygen-demanding organic waste still left over
• Activated sludge process pump sewage into large
  tank and mix for several hours with bacteria-rich
  sludge and air bubbles
• Then goes to sedimentation tank where
  microorganisms and suspended solids settle out as
  sludge

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• Sludge produced is incinerated, sent to landfill
  or treated in biosolids facility
• Secondary removes only tiny fraction of
  radioactive isotopes and persistent organic
  substances such as pesticides

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• 3) Advanced Sewage Treatment
• Water travel through anthracite coal filters that
  remove specific pollutants left in water after
  primary and secondary
• Sometimes not used because cost twice as much to
  build and four times as much to operate as
  secondary plants
• Growing interest in using membrane based
  technologies reverse osmosis, micro filtration,
  ultra filtration and nanofiltration

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• Because of Clean Water Act, most U.S. cities have
  combined primary and secondary sewage treatment
  plants
• Figure 19-17
• Before discharge, water from all three processes
  undergo
• 1) bleaching to remove water coloration
• 2) disinfection to kill disease-carrying bacteria
  (chlorination)

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Treating Sewage by working with Nature

• Sewage Walls
• Run along residential block
• Channels sewage through terraced planters that
  progressively filter and purify the waste
• Living machines
• Look like aquatic botanical gardens, powered by
  sun
• Wastewater garden (Figure 19-19)
• Small, low tech artificial wetland to treat
  sewage
• Water flowing out can be used to irrigate gardens
  or fields or flush toilets

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The Living Machine