Water Pollution and Treatment Chapter 22 Water Pollution and Treatment

Water Pollution Degradation of water quality Any biological, physical or chemical substance that, in an identifiable excess is known to be harmful to other desirable living organisms Heavy metals, sediment, radioactive isotopes, heat, coliform bacteria, phosphorus, nitrogen

Water pollution US EPA has set limits on certain pollutants (contaminants) Difficulties in determining effects of exposure to low levels of pollutants. Standards have been set for a small fraction of more than 700 identified drinking water contaminants.

Surface Water Pollution Water Pollutants are emitted from Point Sources Distinct and confined sources such as pipes from industrial or municipal sources. Old sewage treatment systems Nonpoint Sources Diffused and intermittent Ex) runoffs from streets, agriculture, mining, forestry. Difficult to monitor and control

Biochemical Oxygen Demand The amount of oxygen required for biochemical decomposition process When BOD is high the oxygen content is low, to support life. 3 zones A pollution zone – BOD high An active decomposition zone DO reaches a minimum to actively decompose A recovery zone – DO increases And BOD is reduced

Waterborne Disease Outbreaks of waterborne diseases Milwaukee, WI – Cryptosporidium – 100 deaths Fecal Coliform Bacteria – 1998 Ga Water Park Walkerton, ON – E.Coli – Cow manure washed into water supply wells from heavy rains. 5 people died, 20 ICU, 500 ill – CUT BACKS IN TESTING

Nutrients Eutrophication Cultural Eutrophication The process by which a body of water develops a high concentration of nutrients – Phophorus or nitrogen Cultural Eutrophication When eutrophication is accelerated by human processes that add nutrients to a body of water Fertilizers, detergents, sewage treatment plants

Eutrophication A body of water develops a high concentration of nutrients. The nutrients cause an increase in the growth of aquatic plants as well as photosynthetic blue-green bacteria and algae Algae may form surface mats, shading and reducing light to the algae below; reducing photosynthesis. Algae die and decompose, bacteria feed on the dead algae,BOD increases, oxygen is reduced. Other organisms die.

Acid Mine Drainage Water with a high concentration of sulfuric acid that drains from mines Serious water pollution problem Damages aquatic ecosystems, pollutes bodies of water and degrades water quality

Approaches to surface water pollution Reduce the sources of pollution Most environmentally preferable way Treat the water to remove pollutant Chlorination Filtration Settling Tanks pH adjustments (Lime) VOC removal Nitrate removal

Groundwater Pollution 50% of people in US depend on groundwater as a water source. -Groundwater has always been thought to be PURE -Pollution sources can be dumping chemicals, leaking underground tanks, natural occurring elements

Wastewater Treatment Septic Tank Disposal Systems Waste Treatment Plants Primary Treatment Secondary Treatment Advanced Treatment Chlorine Treatment

Wastewater Renovation and Conservation Cycle Steps: 1. Return of treated wastewater to crops 2. Renovation or natural purification by slow percolation of the wastewater into soil to eventually recharge the groundwater resource with clean water 3. Reuse of the treated water

Water Reuse Inadvertent: Indirect: Direct: water is withdrawn, treated and returned to the environment Indirect: Ex) the wastewater renovation and conservation cycle Direct: The use of treated wastewater that is piped directly from a treatment plant to the next user

Water Pollution and Environmental Law The branch of law dealing with conservation and use of natural resources and control of pollution