Chapter 20Water 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.