evr- water resources and pollution 2

Water pollutants

Natural sources, agricultural runoff, urban sewage

Water Pollution

Primary water pollution problem is the lack of clean, disease-free drinking water; All segments of society may contribute to water pollution

Introduction of more pollutants and increase demand on finite water resources

Increasing population may cause

Bacteria in aquatic systems decompose organic matter, and this process requires oxygen, so more bacterial decomposition = less oxygen in the water available to fish / other organisms; a stream with low oxygen is considered polluted

How is dissolved oxygen an issue in water pollution?

Biochemical Oxygen Demand (BOD)

Amount of oxygen required for biochemical decomposition; Measure of the amount of oxygen consumed by microorganisms as they break down organic matter

– Natural sources – Agricultural runoff – Urban sewage

Source of organic matter include

Excess nitrogen and phosphorus leads to eutrophication

How can excess nutrients be a form of water pollution?

Eutrophication

Excess nutrient inputs cause a large growth in aquatic plants and photosynthetic bacteria and algae. Lowers oxygen content.

Cultural Eutrophication

Human processes that add nutrients to water (Gulfof Mexico Dead Zone)

Ensure that high concentrations of nutrients do not enter water by using phosphate-free detergents, control nitrogen runoff,, dispose and ruse treated wastewater, employ advanced water treatment methods

Solutions to Cultural Eutrophication

Waterborne Diseases

Primary water pollution problem where its effects very from upset stomach to death (ex. cholera); presence indicates fecal matter abundance

Large spills on land and water, some from shipping activities, abandoned oil wells that eventually fail and seep into surface

How does oil become a form of pollution?

Sediment Pollution

Two-fold problem of erosion and reduces the quality of the water resources it enters

Forested areas more stable, agricultural practice can lead to large soil loss, large quantities of sediment lost during construction phase of urbanization

How does and land use affects erosion and sedimentation?

Acid Mine Drainage

Refers to water with high concentrations of sulfuric acid that drains from mines; this water then runs off into natural waterways and

groundwater

Nonpoint source pollutant

Source pollutant that is diffused and intermittent (e.g. runoff) and is difficult to monitor and control

To reduce the sources and to treat the water to remove pollutants or convert them to forms that can be disposed of safely

Two traditional approaches to dealing with surface water pollution

Nanotechnology, Biotechnology

New approaches to surface water pollution

Nanotechnology

Technology solution to surface water pollution that uses extremely small particles to “capture” heavy metals in water

Biotechnology

“Closed-loop” local landscape that acts as a bioretention facility; helps reduce cultural eutrophication

50

___% of all people in the US depend on groundwater for drinking

Concentration or toxicity of the pollutant and degree or exposure of people or other organisms to the pollutant

The hazard presented by a particular groundwater pollutant depends on (2)

Groundwater lacks oxygen but may provide environment for anaerobic bacteria, small and variable movement of channels

Groundwater vs surface pollution

Wastewater treatment industry

Industry responsible for treating water used in industrial and municipal purposes before re-released; often uses septic tanks and centralized treatment

Septic-tank Disposal Systems

Water treatment systems common in many rural areas and outlying areas of cities; prone to issues of pollution

Wastewater Treatment Plant

Specially designed plants that accept municipal sewage from homes, businesses and industrial sites delivered to a plant by a network of pipes that discharge treated water into surface waters

Primary, Secondary, Advanced wastewater treatment

3 Categories of Treatment Plants

Primary Treatment

Raw sewage enters plant, passes through a series of screens, enters a grit chamber, enters sedimentation tank. Removes 35% of BOD

Secondary Treatment

Most common treatment. Deploy activated sludge that has microorganisms to eat organic matter. Removes 35% of BOD

Advanced Wastewater Treatment

Additional pollutants can be removed by adding more treatment steps such as filters and chemicals. This water then can be used for agricultural or municipal irrigation

Chlorine Treatment

Controversial form of wastewater treatment. Effective at killing pathogens, but poses hazard to fish and cancer risk to humans

Natural and constructed wetlands can treat wastewater

Why are wetlands important in wastewater treatment?

Constructed wetlands

Wetlands built in arid regions to treat poor quality water

Water Reuse

Results when water is withdrawn, treated, used, treated again, and returned to the environmen

Direct water reuse

Use of treated wastewater piped directly from treatment plant to end user

Federal Water Pollution Control Act (Clean Water Act 1972)

cleaned up nations water, billions of $ in federal grants for sewage treatment works; covers cleanup and prevention