Chapter 20
Water Pollution and its
Prevention
Types of Pollution
• Point sources: comes straight from a specific
source (ex: specific factory)
• Nonpoint sources: scattered over broad areas
(ex: agricultural runoff)
Wastes and Pollutants
• Organic matter can collect in water and be a
serious threat, raising the BOD (biochemical
oxygen demand) which is defined as the
amount of organic material in water, in terms
of how much oxygen will be required to break
it down chemically, biologically, or both.
• Inorganic chemicals include heavy metals,
acids, and road salts. Organic chemicals
include petroleum and pesticide products.
Types of Pollutants
• Debris and Grit: rags, plastic bags, coarse sand,
gravel.
• Particulate organic material: fecal matter, food
wastes, toilet paper, and other matter.
• Colloidal and dissolved organic material: very
fine particles of particulate organic matter,
bacteria, urine, soaps, detergents, and other
cleaning agents.
• Dissolved inorganic material: nitrogen,
phosphorus, and nutrients.
Treatment
• Primary treatment involves removing debris and grit.
Using a bar screen, these wastes will be taken to an
incenerator. Then water flows to a grit chamber to
settle the grit to be taken to landfills. Then, primary
clarifiers settle organic materials still in the water.
• Secondary Treatment involves using bacteria- such
as natural decomposers and detritus feeders to feed
on organic matter. Sludge will then be taken from the
water and the water will pass through a secondary
clarifier tank.
Eutrophication
• When agricultural fertilizers rich in
phosphorus and fertilizer become runoff and
reach streams and other waterways,
eutrophication occurs. This process facilities
algal blooms on top of these water ways and
slowly depletes dissolved oxygen from
organisms living in these habitats.
Laws
• Federal Water Pollution Control Act of 1948- first federal
action regarding water pollution. However, it did not do much
and left things to the state and local municipalities. Ultimately,
this inaction was seen when the Cuyahoga River in Ohio
caught on fire.
• Clean Water Act of 1972- Charged the EPA with restoring and
maintaining the chemical, physical, and biological integrity of
waters
Drinking Water Standards
• Drinking Water Standards and Health
Advisories- covering some 94 contaminants,
enforceable under Safe Drinking Water Act
(SDWA). Presented as maximum contaminant
levels (MCLs).
More laws!
• Clean Water State Revolving Fund- loan fund
for local governments to borrow and build
treatment facilities.