21 Water Pollution. Overview of Chapter 21 Types of Water Pollution Water Quality Today Municipal...

21 Water Pollution

Overview of Chapter 21

Types of Water Pollution Water Quality Today

Municipal Agricultural Industrial

Improving Water Quality Laws Controlling Water Pollution

© 2012 John Wiley & Sons, Inc. All rights reserved.

Types of Water Pollution

Water pollution Any physical or chemical change in water that

adversely affects the health of humans and other organisms

Problem in developing countries: lack of disease free.

Eight categories Sewage, disease-causing agents, sediment

pollution, inorganic plant and algal nutrients, organic compounds, inorganic chemicals, radioactive substances, and thermal pollution


Sewage

The release of wastewater from drains or sewers Causes 2 serious environmental problems:

Enrichment Fertilization of a body of water by high levels nitrogen and

phosphorus. Sewage and other organic wastes are measures by biochemical

oxygen demand (BOD). Increase in Biological Oxygen Demand (BOD) (in milligrams of

dissolved oxygen per liter of water for a specific number of days at a given temperature). A large amount of sewage in water generates a high BOD which robs

the water of dissolved oxygen. When dissolved oxygen levels are low, anaerobic microorganism

produce compounds with unpleasant orders which deteriorate water quality.

As BOD increases, Dissolve Oxygen (DO) decreases


Sewage


Sewage - Eutrophication

Oligotrophic Unenriched, clear water that supports small

populations of aquatic organisms


Sewage - Eutrophication

Eutrophic Slow-flowing stream, lake or estuary enriched by inorganic plant

and algal nutrients such as phosphorus. The enrichment of water results in an increased photosynthetic productivity. The water in eutrophic lake is a cloudy and usually resembles pea soup b/c of the presence of algae.


Disease-causing Agents

Disease-causing agents are infectious organism that cause disease; they come from the wastes of infected individuals. Municipal wastewater usually contains many bacteria, viruses, protozoa, parasitic worms and other infectious agents that cause human or animal disease.

Infectious organisms that cause diseases Originate in the wastes of infected

individuals Common bacterial or viral diseases:

Typhoid, cholera, bacterial dysentery, polio, and infectious hepatitis


Monitoring for Disease from Sewage

Monitored by testing for presence of E. coli in the water via a fecal coliform test Small sample of water is passed through a filter to trap all bacteria. The

filter is then transferred to a Petri dish that contains agar. Indicates the presence of pathogenic organisms


Monitoring for Disease from Sewage

When dangerous levels of fecal coliform bacteria are discovered in a stream or other body of water. Important to determine source of contamination.

Bacterial source tracking (BST) allows investigators to identify subtle difference in strains of E. coli on the basis of their animal host.


Sediment Pollution

Excessive amounts of suspended soil particles. (clay, silt, sand and gravel are suspended and carried in water.)

Sediment pollution occurs when excessive amounts of suspended soil particles eventually settle out and accumulate on the bottom of a body of water. Originates from erosion of agricultural lands, forest soils exposed by logging,

degraded stream banks, overgrazed rangelands, strip mines, and construction Problems

Sediments that settle out of the water and form a layer over coral reefs or shellfish beds can clog the gills and feeding structures of aquatic animals.

Limits light penetration Covers aquatic animals and plants Brings insoluble toxins into waterways ( which makes the water turbid so cloudy).

This reduces the ability of producers to photosynthesize. Affect water Quality by carrying toxic chemicals both inorganic and organic into

the water.


Inorganic Plant and Algal Nutrients

Nitrogen and phosphorus that stimulate the growth of plants and algae Harmful in large concentrations

Sources: Human and animal wastes, plant residues,

atmospheric deposition, and fertilizer runoff Causes:

Enrichment, bad odors, and a high BOD


Inorganic Plant and Algal Nutrient- The Dead Zone


Dead Zone in Gulf of Mexico: nitrogen and phosphorus from the Mississippi River are largely responsible for huge dead zones.

Dead zones are a sections of the ocean or a sea in which oxygen has been ddepleted to the point that most animals and bacteria cannot survive often caused by runoff of chemical.fertilizers.

Organic Compounds

Chemicals that contain carbon atoms Natural examples: sugars, amino acids, and oils Human-made examples: pesticides, solvents,

industrial chemicals, and plastics


Volatile Organic Compounds in Groundwater


Inorganic Chemicals

Contaminants that contain elements other than carbon Do not degrade easily Lead

Found in old paint, industrial pollutants, leaded gasoline. Contaminates water when the water passes through the

pipes of older homes that contain lead lined pipes brass fitting containing lead and lead containing material.

Exposure can damage the brain nervous system and kidneys.

Mercury Mercury is found in increase concentrations in water as

result of human activities. Coming from the burning of fossil fuels mainly coal, incineration of garbage, hazardous waste, medical supplies, and dental supplies and raw supplies to make cement.

Mercury bioaccumulates in the muscles of top predators of the open ocean. This is found in fish and shellfish.


Radioactive Substances

Contain atoms of unstable isotopes that spontaneously emit radiation

Sources Mining Processing radioactive materials Medical and Research Facilities Nuclear power plants Natural sources


Thermal Pollution

Nonchemical water pollution. Occurs when heated water produced during

industrial processes is released into waterways. Usually occurs when cold water is removed from a natural supply, used to absorb heat as part of some industrial process, and then returned as heated water back to the natural supply.


Thermal Pollution

Organisms affected Temperature affects reproductive

cycles, digestion rates, and respiration rates

Warm water holds less DO than cold water so it increase respiration rate which then suffocate.

Thermal shock- A phenomenon which, dramatic change in temperature can kill many species,


Two Types of Water Pollution

Point Source Pollution Water pollution that can be traced to a specific origin. Distinct

locations such as particular factory that pumps its waste into a nearby stream or a sewage treatment plant that discharges it wastewater from a pipe in an ocean.

Non-point Source Pollution Pollutants that enter bodies of water over large areas rather than

being concentrated at a single point of entry Diffuse, but its cumulative effect is very large Example: Entire farming region, suburban community with many

lawns and septic system or storm runoff from parking lots. It is important to differentiate between the 2 types of pollution

sources because the distinction can help in controlling polluants inputs to waterways.


Water Pollution from Agriculture

Agriculture is leading source of water pollution in US Animal wastes and plants residues have high

BOD Chemical pesticides can leach into groundwater

Almost all streams and rivers are polluted with agricultural pesticides 72% of water pollution in rivers is from agriculture


Municipal Water Pollution


Industrial Wastes in Water

Different industries generate different pollutants Food processing plants - high BOD Paper mills - High BOD and toxic compounds

Many industries recover toxins before they go into the waste stream


Case-In-Point Green Chemistry- Sources of synthetic pollutants in water


Groundwater Pollution


Water Pollution in Other Countries

Lake Maracaibo, Venezuela 10,000 drill platform oil wells tap lake bottom

Leak oil into lake

Agricultural wastes from local fields

Until recently, raw human waste polluted the lake



Po River, Italy Similar to Mississippi River Pollutants: Sewage, industrial wastes, sediment ~17 million Italians depend on the river for

drinking water Cleanup will require a national management plan

and may take decades



Ganges River, India Used for bathing and

washing clothing Sewage and industrial

waste discharged into river

Ganga Action Plan initiated by government Construction of 29

sewage treatment plants


Purification of Drinking Water



In US most municipal water supplies are treated

Collected from water or reservoir Treated Treated water distributed to customers Sewer lines bring sewage to treatment plant Sewage treated at sewage treatment plant



Chlorine Dilemma Chlorine byproducts are linked to numerous cancers,

miscarriages and birth defects Peru stopped using chlorine

1991 - huge cholera epidemic that infected 300,000 people

Fluoridation 70% of US drinking water is fluoridated Prevents tooth decay Once believed to be linked to cancer, kidney disease -

current studies do not show this


Municipal Sewage Treatment

Primary treatment Removing suspended and floating particles by

mechanical processes Secondary treatment

Treating wastewater biologically to decompose suspended organic material; reduces BOD


Secondary Treatment

Most common treatment, activated sludge. Wastewater from primary sedimentation tank enters

the tank Then enters the final sedimentation tank

Sludge settles out Some activated sludge used again in aeration

Most of the sludge transported to digester Wastewater from final tank is disinfected w/ chlorine

and discharged

Secondary Treatment

Secondary treatment removes ~90% of BOD Sludge from the digester is dried and disposed

of in a landfill, burn, anaerobic digestion, or applied to improve soil.


Sewage Sludge Solids remaining after primary and secondary

sewage treatment has been completed Tertiary treatment

Advanced wastewater treatment methods that are sometimes employed after primary and secondary treatments

Reduce phosphorus and nitrogen


Individual Septic System-Septic Tank


Individual Septic System-Drain Field


Laws Controlling Water Pollution

Citizen Watchdogs to Monitor Pollution Clean Water Act- (1972) supports the “protection and

propagation of fish, shellfish, and wildlife and recreation in and on the water”.

-Issued water quality standards that defined acceptable limits of various pollutants in U.S. waterways.

Safe Drinking Water Act- (1974, 1986, 1996) sets the national standards for safe drinking water.

- It is responsible for establishing maximum contaminant levels (MCL) for 77 different elements or substances in both surface water and groundwater.


Laws that Protect Groundwater

Safe Drinking Water Act National Pollutant Discharge Elimination

System (NPDES) Resource, Conservation and Recovery Act


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