GLG 110
Part 3
Chapter 11
Water Pollution and Treatment
60%
of coral reefs worldwide are threatened by human activity
Coastal
pollution is a serious issue in many coastal communities
11.1
An Overview of Water Pollution
Water pollution: degradation of water quality (measured by biological,
chemical, physical criteria)
The problem is extremely variable
Significant
are residence time (how long a pollutant lasts) and reservoir size (how big is
the body of water)
Pollutants in groundwater have a relatively long residence time
11.2
Selected Water Pollutants
Oxygen-Demanding Waste:
Bacteria using up high amounts of oxygen causing other organisms to die
Pathogenic Organisms:
e.g. cholera, typhoid infections, hepatitis, dysentery
these pathogens are difficult to monitor, therefore we use fecal coliform
bacteria counts (mostly harmless, from human waste)
Nutrients:
Most important are phosphorus and nitrogen
Levels are related to land use (e.g. agriculture and fertilization)
High levels will cause “cultural eutrophication” of water
Oil: most likely due to tanker accidents at sea
Military activity (war) may also contribute to problem
Toxic Substances: e.g. hazardous chemicals, heavy metals, radioactive materials
Sediments: usually non-toxic but cloud the water
Thermal Pollution: rising the water temperature (e.g. industrial operations and
power plants)
11.3
Surface-Water Pollution and Treatment
Occurs when too much of an undesirable or harmful substance is discharged into
a surface body of water
Point Sources of Surface-Water Pollution
They are discrete and confined (e.g. pipes)
They are regulated by permits
Water from different sources should not be mixed
They are diffused and intermittent
They are difficult to control
e.g. forestry, agriculture, mining
Reduction of Surface-Water Pollution
Laws are passed to reduce pollutants entering the rivers
Use of natural filters for pollutant reduction (e.g. sand, gravel)
11.4
Groundwater Pollution and Treatment
50% of
Toxic chemicals pose the greatest threat (e.g. fertilizers, pesticides, fuels)
Subsurface pollution is usually hard to detect and harder to treat
Saltwater intrusion: overpumping of groundwater in coastal areas
Groundwater Treatment
Steps to correct groundwater pollution are:
Characterizing the geology
Characterizing the hydrology
Identifying the contaminants and their transport processes
Initiating the treatment process
11.5
Water Quality Standards
How save is our water supply?
EPA establishes minimum national drinking water standards
Maximum Contaminant Levels are established for “each” substance in water
Substances which pose the greatest threat if standard is exceeded:
coliform bacteria, nitrate
11.6
Wastewater Treatment
Water is usually degraded after use
Consequently, water must be treated before released into environment
Septic-Tank Sewage Disposal (see Fig.11.10)
In US: more than 22 million septic tank systems are in operation!
This is 30% of the population!
Not all land is suited for septic tank use
Wastewater Treatment Plants (see Fig. 11.11)
Several steps are used to treat water:
Step one: primary treatment
Screening and sedimentation (removal of grit and solids)
Step two: secondary treatment
Most common method is activated sludge
Air and bacteria are pumped into tanks to break down nutrients
Step three: advanced treatment
Removes nutrients, heavy metals, and specific chemicals
What to do with the sludge?
Wastewater Renovation
11.7
Water Law and Federal Legislation
Water is the most important natural resource on Earth
Water resources are the most legislated commodity in the area of environmental
law
Surface-Water Law
Two groups of states in the
The Riparian Doctrine states
The Prior Appropriation Doctrine states
The Riparian Doctrine:
Mostly used in the eastern states
The right to use water is real property, but water is not
Owners of land cannot infringe on other land owner’s water rights
The Prior Appropriation Doctrine:
The first user of water has the right to use the water
Commonly used in western states
Groundwater Law
Rules are based on the English Rule or Absolute Ownership Doctrine
Land owners can pump as much water as they want from wells
This works well is
In the west: American Rule (Reasonable Use Doctrine) is applied
Water can be used in a reasonable way (which may vary widely)
In
All landowners have the same rights
Federal Water Legislation
Refuse Act of 1899
Federal Water and Pollution Control Act of 1956
Fish and Wildlife Coordination Act of 1958
National Environmental Policy Act of 1969
Water Quality Improvement Act of 1970
Federal Water Pollution Control Act (Clean Water Act) of 1972
Comprehensive Environmental Response, Compensation, and Liability Act of 1980
Hazardous and Solid Waste Amendments to the Resource Conservation and Recovery
Act of 1984
Water Quality Act of 1987
Safe Drinking Water Act of 1996
Study
questions are on page 316.