1. Chapter 21: Water Pollution

2. 21.1 Water Pollution Water pollution: the degradation of water quality
A pollutant is any biological, physical, or chemical substance that is harmful to desirable living organisms
Water pollutants include…
heavy metals, sediment, certain radioactive isotopes, heat, fecal coliform bacteria, phosphorous, sodium, nitrogen, and pathogenic bacteria and viruses.

3. Pollutant Category Comments
Examples of Sources
Comments
Dead organic matter
Raw sewage, agricultural waste, urban garbage
Produces BOD and diseases
Pathogens
Excrement & urine
Recent cholera epidemics in Africa
Organic chemicals
Pesticides, herbicides, industry that makes dioxin
Seep thru ground during planting
Nutrients
Phosphorous, nitrogen from lead use (urban & agriculture)
Major cause of artificial eutrophication
Heavy metals
Agricultural, urban & industry using mercury, lead, selenium, cadmium, etc.
Mercury from industrial processes discharged into water
Acids
Sulfuric acid from coal and mines into groundwater
Acid mine drainage is major pollution problem
Heat (thermal pollution)
Hot water from power plants
Causes ecosystem distruption
Sediment
Construction and agricultural runoff; natural erosion
Loss of soil resources, low water quality
Radioactivity
Nuclear power industry, military, natural sources
Health effects vigorously debated

4. Major uses for water today:
Agriculture: Most vegetation can tolerate a wide range of water quality, allowing for agricultural water to vary in physical, chemical, and biological properties.
Industrial Processes: The quality of water needed for industrial purposes varies widely depending on what the process involves; some processes need distilled water, or water with a specific quality.
Domestic (Household) Supply: Water in a domestic supply must be free of any materials harmful to health or household plumbing and appliances i.e. Insecticides, pesticides, pathogens, etc.

5. 21.1 Water Pollution
Some pollutants may be a pollutant to one environment, but not to others
The primary problem with water pollution today is a lack of clean, disease-free drinking water
The U.S. treats drinking water before consumption, eliminating most waterborne diseases, but in many other parts of the world this is not the case.
Major uses for water today include agriculture, industrial processes, and domestic supply.

6. Domestic Water Use: How safe is it?
Water for domestic use is drawn from surface and groundwater
It is stored in reservoirs and ponds so solids and sediment settle increasing the clarity
All water must then be treated to meet national drinking water standards (see p424)
Next, the water is run through a water plant where it is filtered and chlorinated
Once it reaches people’s homes it is treated even further through charcoal filters in the tap
Many people do not like to drink tap water because it runs through metal pipes and contains chlorine, but the drinking water in the US is considered the safest in the world and the added chlorine is necessary because it eliminates waterborne disease
Although our drinking water may be the safest in the world, little is known of the long term effects of the minimal amounts of toxins that are contained in the water
These may be heavy metals and organic chemicals that require more research
These concerns have caused the bottled water industry to become a multi-billion dollar industry

7. 21.2 Biochemical Oxygen Demand (BOD)
When there is dead organic matter in a stream, bacteria breaks it down using oxygen from the water
If there is too much bacterial activity due to dead material, the oxygen supply will deplete and make a zone inadequate to sustain life for other organisms
Therefore, a stream with a low enough oxygen level is considered polluted
The Biochemical Oxygen Demand is the amount of oxygen required for the biochemical decomposition process
Scientists determine water quality by measuring the amount of oxygen consumed by microorganisms as they break down organic matter in small samples
This is commonly practiced at wastewater treatment plants
Dead organic matter comes from sources such as leaves falling off a tree, agricultural runoff, and runoff from urban sewage
An example of too much organic matter going into a body of water at once is a sewage treatment plant that overflows from storm runoff and runs off into streams untreated
This could cause the oxygen supply to become too low to support life in the water
This also causes three zones to form in the water
1) pollution zone: High BOD
2) Active decomposition zone: dissolved oxygen content reaches a minimum due to rapid decomposition
3) recovery zone: dissolved oxygen increases and BOD is reduced

10. Sources and Processes of Water Pollution:
Surface Water
Ground Water
Urban Runoff
Leaks from waste disposal sites
Agricultural Runoff
Leaks from buried tanks and pipes
Accidental spills of chemicals
Seepage from agricultural activities
Radioactive materials
Saltwater intrusion into coastal aquifers
Runoff from industrial sites
Seepage from cesspools and septic systems
Leaks from storage tanks/pipelines
Seepage from acid-rich water from mines
Sediment from sources ie. Agricultural lands and construction sites
Seepage from mine waste piles
Air fallout into rivers, lakes, and oceans
Seepage from pesticides, herbicide nutrients, etc.
Seepage from accidental spills
Inadvertent seepage of solvents and chemicals from industrial sites.
Sources and Processes of Water Pollution:
An increasing population often results in increases pollutants in the environment.
The U.S. Environmental Protection Agency has set thresholds on water pollution levels for some pollutants. If the pollutant is present in a greater concentration that the threshold the water in unsuitable for use.

11. 21.9: Groundwater Pollution
Groundwater- water found beneath the Earth’s surface within the zone of saturation under the water table
Almost 50% of Americans’ drinking water comes from groundwater
This concerns environmentalists; groundwater can be easily polluted by hard-to-detect toxins
Only a small portion is known to be contaminated, but as groundwater contamination testing is becoming more commonplace, we’re finding higher proportions of contaminated groundwater

12. Causes of Groundwater Pollution
Increasing human population increases stress on groundwater supply
Runoff from precipitation
Road salts, oil, fertilizers, pesticides
Waste disposal sites in the US are producing chemical plumes that migrate into the groundwater
Approx. 75% of 150,000 sites suspected of this

13. 5 Principles of Groundwater Pollution
Some pollutants, like gasoline, are lighter than water; float on the groundwater
Some pollutants have 3 phases: liquid, vapor and dissolved.
Dissolved phases chemically combine with groundwater. Ex: salt dissolves in.
Some pollutants are heavier than water, and sink downward thru the groundwater
Particulates, cleaning solvents
Treatment must address physical and chemical properties of the pollutant
Ex: extraction well for gas because gas floats on water
Emphasis should be placed on prevention of pollution instead of clean up (cheaper, less environment damage)

14. Treatment Options
Bioremediation – A method of treating groundwater pollution problems that utilizes microorganisms in the ground to consume or break down pollutants
Vapor extraction system
A well pump extracts vapor from gasoline underground before it affects water in homes
Removal and disposal of soil (near contaminated areas)
Very expensive; big environmental consequences

16. Case Study: Long Island
Nassau county: groundwater pollution caused by saltwater infiltration and shallow aquifer contamination
Shallow-aquifer pollution associated with urbanization
Urban runoff, household sewage from cesspools and septic tanks, salt (for de-icing highways) and industrial and solid waste
Pumping of groundwater over the past 15 years has led to declining water levels
As groundwater is removed from coast, subsurface outflow to ocean decreases, allowing salt water to migrate inland

17. Saltwater Intrusion

18. 21.10 – Wastewater Treatment
When used for industrial or municipal purposes, water is often degraded
Wastewater Treatment – Process of treating wastewater (primarily sewage) in specially designed plants that accept municipal wastewater. Generally divided into three categories: Primary treatment, secondary treatment, and advanced waste-water treatment

19. 21.10 – Wastewater Treatment
Conventional Methods:
Septic tank disposal systems in rural areas
Centralized water treatment plans in cities
Recent innovative approaches:
Application of wastewater to the land
Wastewater renovation and reuse

20. 21.10 – Septic Tank Disposal Systems
In rural areas, there is no central sewage systems or wastewater treatment facilities available
Result: individual septic tanks
By law, an evaluation is needed for the site of a potential septic tank

22. 21.10 – Primary treatment
Incoming raw sewage enters the plant’s sewer line
Sewage then enters the grit chamber
Then enters the primary sedimentation tank
Sludge is removed and transported to the digester for further processing
Removes 30 to 40% of BOD

23. 21.10 – Secondary Treatment
Most common method of secondary treatment is activated sludge
Wastewater from primary sedimentation tank enters the aerotation tank
Waste water mixed with air
Enters the final sedimentation tank, sludge settles out
Treated by anaerobic bacteria
Discharged to a river, lake, or ocean
Removes about 90% of BOD

25. 21.10 - Advanced Wastewater Treatment
Primary and secondary treatment do not remove all pollutants from incoming sewage
Additional pollutants can be removed by adding more steps of treatment
The treated water is released into the surface water and can be used for irrigation or municipal properties
Advanced wastewater treatment is used when it is important to maintain good water quality

26. 21.10 – Chlorine Treatment
Chlorine is frequently used to disinfect water in the process of wastewater treatment
It’s very effective in killing the pathogens that have historically caused outbreaks of serious waterborne diseases
It has been recently discovered that chlorine treatment produces very small quantities of chemical byproducts
Some of these are potentially hazardous to humans and animals
How much of a risk these chemical byproducts are is a matter of debate and is rather controversial
However, evidence suggests that these byproducts create a risk of cancer and other possible side effects

27. 21.11 Land Application of Wastewater
Wastewater renovation and conservation cycle - First is returns treated water to crops via irrigation systems, then it naturally purifies water wastewater through percolation (renovation), and lastly it reuses the treated water.

28. 21.11 Land Application of Wastewater
Resource recovery wastewater treatment plant- Both environmentally preferred and economically viable. It uses methane gas as fuel.
How it Functions- First wastewater is run through filters, then it is put through anaerobic processing, and finally the nutrient rich water is run over an incline and onto plants.

29. 21.11 Land Application of Wastewater
Wastewater and wetlands
Treating wastewater through wetland systems is attractive to communities that find it difficult to purchase wastewater treatment plants.
Louisiana applies nitrogen and phosphorus rich wastewater to wetlands and increases plant production/ improves water quality.
Arizona constructed artificial wetlands that contain bacteria that reduce Nitrate concentration in the wtaer.

30. 21.12- Water Reuse Water reuse can be inadvertent, indirect, or direct
Inadvertent- water is withdrawn, treated, used, treated, and returned to the environment, followed by further withdrawals and use
Millions depend on it who live near large rivers
Risks- poor treatment= poor water quality
Diseases or viruses may develop before or after treatment, making potential health risks
New diseases may form

31. Indirect water reuse Planned water usage
US used several thousand cubic meters of treated wastewater per day to be applied to surface recharge areas
Treated water enters ground water storage to be reused for agricultural and municipal purposes

32. Direct water reuse
Treated water is pumped directly from a treatment plant to the next user
Used in agriculture, industry, irrigating golf courses, on institutional grounds, and parks
Growing rapidly
Las Vegas hotels use water from rivers, fountains, canals, and lakes (required to treat and reuse waste water)
Little direct use of water is used for human consumption (except in emergencies) because of risks and negative cultural attitudes toward using treated water

33. 21.13 Water Pollution and Environmental Law
Environmental Law- branch or law dealing with conservation and use of natural resources and control of pollution
In the US, laws at the federal, state, and local levels address these issues
First federal law to protect water resources- Refuse Act of 1899 = protected navigable streams, rivers, and lakes from pollution
Many federal laws have been passed to clean up or treating pollution problems or treating wastewater.
Also, there has been a focus on preventing pollutants from entering water
Prevention has the advantage of avoiding environmental damage and costly cleanup/treatment

35. Water Laws 1990’s was a time of debate in the US over water pollution.
US tried to rewrite the Clean Water Act in 1994 to give industry more flexibility to comply with environmental regulations with water pollution
Gov. saw this as a way to save money without causing environmental degradation
Environmentalists saw it as a step backwards to cleaning up water resources.
Congress was wrong; people are willing to pay more for clean water
Unfortunately, congress continues to debate and little has been resolved

36. Water Laws
In 2000, the US president aimed to protect thousands of streams and lakes from nonpoint agricultural, industrial, and urban pollution sources.
This will be enforced by the Environmental Protection Agency, which will work with local communities and states to develop plans to reduce pollution in streams, lakes, and estuaries
Problems- It is difficult to regulate, it will take 15 years to implement completely, and it has been opposed by Congress, agricultural groups, the utility industry, and the US Chamber of Commerce.
Main objections- it is costly (billions of dollars) and that local and state gov’ts are better suited to control their own water pollution regulations
The god news is that these regulations mark a new phase in water pollution control in the US