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Chapter 14

Water Pollution

Dr. Joao Santos

Chapter 14

Water Pollution

Dr. Joao Santos

Case History: NC Bay of Pigs (1)

• Hurricane Floyd through NC in Sept 1999, forcing 48,000 people into shelters and killing 50 people

• Estimated 30,000 hogs, 2 million chickens, and 735,000 turkeys died

• Catastrophic water pollution as a result of the floodwater from Hurricane Floyd

• More than 38 pig waste lagoons washed out, 250 million gallons of pig wastes into creeks, rivers, and wetlands

• North Carolina has a long history of hog production, the population of pigs swelled from about 2 million in 1990 to over 10 million by 1997. Approximately 250 pig operations flooded out

• Polluted water through schools, churches, homes, and businesses

Case History: NC Bay of Pigs

Case History: NC Bay of Pigs (2)

• In 1997, a state law was enacted that prohibited building new waste lagoons and sewage plants on floodplains

• In the spring of 1999, the governor proposed a 10-year plan that would phase out the state’s 4,000 animal waste lagoons

• Hurricane Floyd occurred before these changes could be enacted

• In 2007, the state passed legislation to ban construction or expansion of new lagoons and spray fields

• On-site treatment facilities to replace swine lagoons

Water Pollution

• Water pollution: Refers to degradation of water

quality as measured by biological, chemical, or

physical criteria

• Pollutants: Any substance that, in excess, is known

to be harmful to desirable living organisms

• The greatest water pollution problem in the world

today is lack of disease-free drinking water for

about 20 percent of the world’s population

• Waterborne diseases that kill about 2 million people

a year, and most of the deaths are of children under

the age of 5

Common Pollutants (1)

• Oxygen-demanding waste (common organic waste)

• Pathogenic waste (pathogenic microbes)

• Nutrients

• Petroleum (oil)

• Toxic waste (chemicals, heavy metals, radioactive waste)

• Sediment

• Thermal plumes

Common Pollutants (2)

• Oxygen-demanding waste

– Dead organic matter decomposed by bacteria, an oxygen-demanding process

– BOD: High BOD associated with a high level of decaying organic matter in water, reducing DO (dissolved O) for other healthy organisms

– Sources of oxygen-demanding waste: Natural processes, agricultural applications, urban sewage, and runoff

Common Pollutants (3)

• Pathogenic microbes

– Fecal coliform bacteria

– Harmful risks (diseases and death ) of E. coli

– Billions exposed to waterborne diseases, especially in poor countries

– Outbreaks do occur in developed countries (e.g., GA’s water park in 1998; Walkerton public water supply, Ontario in 2000; CA spinach contamination in 2006)

– Epidemic risks of waterborne diseases during natural disasters, such as earthquake, tsunami, flooding

Common Pollutants (4)

• Nutrients

– Two important nutrients: N, P

– Major problems: Cultural eutrophication — algae bloom, triggering BOD problem

– Major sources for nutrients: Fertilizer, feedlots, and discharge from wastewater treatment plants

– Areas of certain land use: Agriculture and urban

Common Pollutants (5)

• Oil

– Major problems: Polluted water, ecosystem damage, interrupted socioeconomic conditions of a community

– Major sources: Oil spills from tankers and pipelines, on- or off-shore oil production, war (e.g., the Gulf war, 2006 war in Lebanon)

Common Pollutants

Common Pollutants (6)

• Toxic waste

– Synthetic organic chemicals, up to 100,000 chemicals in use, especially those POPs (persistent organic pollutants)

– Heavy Metals: Pb, Hg, Zn, Cd (e.g., lead contamination)

– Radioactive materials

Common Pollutants (7)

• Sediment pollution

– Sand and smaller particles

– Polluted streams, lakes, reservoirs, even ocean water

– Major sources: Soil erosion, dust storms, floods, and mudflows

– Greatest water pollutant by volume

Common Pollutants (8)

• Thermal pollution

– Temp increases, less dissolved oxygen

– Adverse changes to the habitats of organisms

– Economic impacts

– Major sources: Hot-water discharge from industrial operations, power plants, abnormal ocean currents

Surface Water Pollution and Treatment (1)

Point sources of pollution

• Point sources are discrete, confined, and more readily identifiable

• Common sources: Landfills, discharge from wastewater treatment plants, discharge from industries, power plants, storm water runoff, etc.

• Identify sources, on-site treatment and mitigation, prevention

Surface Water Pollution and Treatment (2)

• Nonpoint sources of pollution: Influenced by such factors as land use, climate, hydrology, topography, native vegetation, and geology

– Nonpoint sources are diffused, intermittent, and hard to specifically identify

– Causes of nonpoint pollutions often regional, cumulative and compound

– Influenced by land use, climate, hydrology, topography, and geology

– Common sources: Urban runoff, agricultural, mining (acid rain and acid drainage)

Acid Mine Drainage

• Acid mine drainage: refers to acidic water with elevated concentrations of dissolved metals that drains from coal or metal mines

• Acid mine drainage is water with a high concentration of sulfuric acid (H2SO4)

• Acid mine drainage is produced by complex geochemical and microbial reactions

• The acid water is extremely toxic to plants and animals in aquatic ecosystems

• The Tar Creek area in Oklahoma was at one time designated by the EPA as the nation’s worst example of acid mine drainage

Acid Mine Drainage

Groundwater Pollution (1)

• Why care about ground water pollution?

– Most abundant freshwater source

– Growing dependency on groundwater

– About 50 percent of people in United States depend on groundwater for drinking water

– Triggers other environmental problems: Water pollution, subsidence, saltwater intrusion, etc.

Groundwater Pollution (2)

• It is estimated that 75 percent of the 175,000 known waste-disposal sites in the country may be producing plumes, or bodies of contaminated groundwater

• Groundwater pollution hazard impact depends on

– Amount of contaminant discharged

– Chemical concentration or toxicity

– Degree and duration of exposure of people or other organisms to the pollution

National Water-Quality Assessment

Program

• In the past 25 years, great improvements in manufacturing, processing, and wastewater-treatment facilities

• The program integrates both surface-water and groundwater systems that monitor and study aquatic ecosystems

• The goals of the program are to:

• Carefully describe current water-quality conditions for many of the freshwater streams and aquifers in the United States

• Monitor and describe water-quality changes over time

• Increase understanding concerning the human and natural factors that affect the nation’s water quality

Groundwater Pollution versus Surface

Water Pollution

• Residence time difference

• Environmental conditions: Inflow, flow rate, dissolved oxygen, sunlight

• Harder to track pollution sources

• More difficult and expensive to clean up

• May pose long-term risks

Infiltration of Urban, Industrial, and

Agricultural Runoff

The Delaware River basin: A large water systems under study

• Effects of the river system on the distribution, fate, and effects of contaminants in water, sediment, and living things

• Relationships between the water flow in the river and concentrations of nutrients, contaminants, and pathogens

• Presence of contaminants, including pathogens and pesticides, in drinking water supplies and recreational activities

• Development of management plans and strategies for the protection of river basin that have high water quality

• Effects of septic systems on water quality and river ecology

• Effects of groundwater withdrawals on water quality

• Effects of discharge from coal mines on water quality

Water Quality and Stream Ecosystems

in the United States

Saltwater Intrusion

• More than half of the world’s population lives in or near the coastal zones

• Groundwater pollution from saltwater intrusion is not a local isolated problem

• Causes major water supply problems in NY, FL, CA

• Case History: Long Island

Saltwater Intrusion Mechanism

• Water table is inclined toward the ocean

• Wedge of saltwater is inclined toward the land

• Over-pumping of groundwater

• Severe drawdown of groundwater causes saltwater ascension

Saltwater Intrusion

Groundwater Treatment (1)

• Pretreatment studies

– Identify contaminants and their characteristics of transport behavior

– Identify the characteristics of aquifer geology (factors controlling groundwater flow—physical dimensions, structure)

– Determine the hydrologic characteristics of polluted aquifer(s)—flow direction, flow rates, discharge and recharge conditions

– Select possible treatment strategies and methods

Groundwater Treatment (2)

Water Quality Standards

• MCLs—Maximum Contaminant Levels

• Permissible limits for 83 contaminants

• MCLGs—Maximum Contaminant Level Goals

– The maximum level at which no adverse health effects from a lifelong exposure

• SMCLs—Nonenforceable limits for contaminants that affects aesthetic qualities in drinking water

Wastewater Treatment

• Law: Used wastewater must be treated

• Break the potential vicious cycle of wastewater entering the general water cycle

• Tier treatment and reuse system

– Septic system—rural residential areas

– Water treatment plant for towns and urban cities

– Innovated ways for recycling and reclaiming wastewater

– New technologies for innovative wastewater treatment

Septic Tank Sewage Disposal System

Idealized Diagram for Wastewater

Treatment Plant

Wetlands as WW-Treatment Sites

• Both natural and human-constructed wetlands: good places to treat or partially treat wastewater (WW)

• For communities with difficulty purchasing expensive WW treatment plants or desire a good alternative

• Warm-humid and hot-dry climates had successful experiences

WW Renovation and Conservation Cycle

Federal Legislation

• The Clean Water Act of 1972 (amended in 1977)

• Survey after survey show strong public support for

a clean environment in the United States today

• The Water Quality Act of 1987 established national

policy to control nonpoint sources of water pollution

• In July 2000, President Clinton imposed new water

pollution controls, The plan will take at least 15

years to implement completely

Reduce Effects of Water Pollution

• Develop and refine better ways to evaluate water pollution problems and their impact on aquatic life and the health of people

• Implement new and innovative, cost-effective water treatment technologies

• Develop products and processes that minimize production of water pollutants and their release into the environment

End of Chapter 14