agec5001 water pollution

characteristics of water pollution control

• recreation benefits (much more important, compared to air pollution)

• large economies of scale in treating sewage to create centralized treatment plans

• difficult source identification (ie. agricultural/street runoff)

2 primary sources of water

surface water (ie. rivers, lakes) & groundwater

point sources

specific discharge locations (ie. pipes, outfalls)

nonpoint sources

diffuse contamination (ie. agricultural runoff, urban stormwater)

3 main primary sources of ocean pollution

1. oil spills from tankers

2. ocean dumping (ie. sewage, chemicals)

3. marine trash (primarily plastics)

degradable wastes

a type of fund pollutant; organic residuals broken down by bacteria

thermal pollution

a type of fund pollutant; heat injection into watercourses

dissolved oxygen (DO)

the amount of oxygen gas that is physically dissolved in water; a measure of water quality — high DO = high water quality

biochemical oxygen demand (BOD)

the amount of dissolved oxygen in bodies of water that micro-organisms need to decompose organic material; measure of water quality — low BOD = high water quality

what does low oxygen in water lead to?

organismic mortality

• very low oxygen → anaerobic conditions → ecological disaster

groundwater contamination

occurs when pollutants seep thru soil and leach into water-saturated regions

once groundwater is contaminated…

• fewer natural cleansing processes

• small replenishment rate = little dilution to the pollutants

• creates a long-term contamination problem

goals of the clean water act (1972)

1. eliminate discharge of pollutants by 1985

2. achieve fishable & swimmable water by 1983

the tech-based approach to the clean water act (1972)

core idea: required all polluters to install the best pollution-controlling tech available to proactively protect bodies of water

key components: 

• best practicable control tech (BPT)

• best available tech that’s economically achievable (BAT)

• sewage treatment plants must treat their wastewater to a specific standard before discharging it

• permits required for all pollutant dischargers

*key flaw: uniform standards for all factories, with no consideration of local water conditions