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Environmental Sciences: Towards a Sustainable Future Chapter 17. Water: Pollution and Prevention. Introduction:. Mississippi watershed. Mississippi River. The Mississippi river and its tributaries encompass 40% of the US land mass. Eventually delivers water to the Gulf of Mexico.

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Mississippi watershed

Introduction: 17

Mississippi watershed

Mississippi river
Mississippi River 17

The Mississippi river and its tributaries encompass 40% of the US land mass.

Eventually delivers water to the Gulf of Mexico.

As tributaries travel through agricultural land they carry fertilizer runoff to the Mississippi then to the Gulf.

Dead zone
Dead zone 17

Nitrogen carried to the marine waters causes eutrophication.

Eutrophication causes an area of depleted oxygen (dead zone)

This was noticed by biologists in 1974 who thought it to be similar to the occurrence at Chesapeake Bay which has seasonal hypoxia (depleted oxygen/dead zone) but later became aware of the connection between nitrogen and the hypoxia.

Gulf fisheries
Gulf Fisheries 17

With the dead zone expanding, the Gulf fishing industry was eventually affected.

$2.8 billion enterprise

Gained national attention and eventually congress passed the Harmful Algal Bloom and Hypoxia Research and Control Act.

Two key strategies
Two key strategies 17

  • The two key strategies to mitigating the problem are:

    • Reduce nitrogen loads to streams and rivers in the Mississippi basin by using less fertilizer and thereby reducing farm runoff.

    • Restoring and promoting nitrogen retention and denitrification processes in the basin.

Dead zones around the world
Dead zones around the world: 17

Since 1960 the number of dead zones has doubled every decade.

Worldwide, over 200 dead zones are now known according to the UN environment program.

Pollution 17

  • EPA defines Pollution: “the presence of a substance in the environment that because of its chemical composition or quantity prevents the functioning of natural processes and produces undesirable environmental and health effects.”

How does it get there
How does it get there: 17

  • Pollutants are almost always the byproducts of otherwise worthy activities…

    • Planting crops, creating comfortable homes, providing energy and transportation, and manufacturing products.

Pollution categories
Pollution Categories 17

  • Air

    • Particulates

    • Acid-forming compounds

    • Photochemical smog

    • CO2

    • CFC’s

Pollution categories1
Pollution Categories 17

  • Water and land

    • Nutrient oversupply

    • Solid wastes

    • Toxic chemicals

    • Pesticides/herbicides

    • Nuclear waste

Controlling pollution
Controlling pollution 17

  • The general strategies to making sure that pollution will not jeopardize current and future generations:

    • Identify the pollutants

    • Identify the source

    • Clean up the environment already impacted

    • Develop and implement pollution control

    • Develop and implement alternative means of meeting the need that do not produce the pollution.

Point source pollution
Point source pollution: 17

Involves discharge of substances from factories, sewage systems, power plants, underground coal mines and oil wells.

Relatively easy to identify.

Easier to regulate.

Nonpoint source pollution
Nonpoint source pollution 17

Scattered over broad areas such as runoff, storm water drainage, atmospheric deposition.

Harder to identify source

Harder to regulate

Strategies to control water pollution
Strategies to control water pollution: 17

  • Reduce or remove the source

  • Treat the water before it is released so as to remove pollutants or convert them to harmless forms.

    • Water treatment is the best option for point source

    • Source reduction can be employed for both point and non point and is the best option for non point.

Types of water pollutants
Types of Water Pollutants 17

  • Pathogens

  • Organic Wastes

  • Chemical

  • Sediments

  • Nutrients

Pathogens 17

  • Disease-causing bacteria, viruses and other parasitic organisms (Table 17.1)

  • Safety measures

    • purification of public water supply

    • sanitary collection/treatment of sewage

    • sanitary practices when processing food

Modern medicine
Modern medicine 17

  • Beside modern medicine, the following have been important factors in controlling waterborne disease:

    • Purification and disinfection of public water supplies

    • Sanitary collection and treatment of human and animal wastes

    • Maintenance of sanitary standards in all facilities in which food is processed or prepared

    • Instruction in personal and domestic hygiene

Good health
Good health 17

Good health is primarily a result of prevention of disease through public-health measures.

Millennium development goal seven
Millennium Development Goal Seven 17

To cut in half the amount of people living without sustainable access to safe drinking water and basic sanitation by the year 2015.

Cholera outbreaks
Cholera Outbreaks 17

  • Peru, 1990.

    • Several thousand people died due to a cholera outbreak caused by unsanitary conditions.

  • Sudan, 2006

    • Civil unrest lead to disruption of sanitation practices, several thousand sick, 500 dead from cholera.

Environmental sciences towards a sustainable future chapter 17
DO 17

Dissolved oxygen

The amount of oxygen that water can hold in solution is very limited.

In cold water dissolved oxygen can reach 10 ppm and even less in warm water.

Organic wastes
Organic Wastes 17

  • Dissolved oxygen (DO) in the water is depleted during decomposition of organic wastes.

  • Water quality test.

    • Biochemical oxygen demand (BOD): measure of the amount of organic material.

    • As BOD increases, dissolved oxygen decreases.

    • If the system goes anaerobic, only bacteria can live.

Chemical pollutants
Chemical Pollutants 17

  • Inorganic chemicals

    • Heavy metals, acids, road salts

  • Organic chemicals

    • Petroleum, pesticides, detergents

Biomagnification 17

Pollutants are concentrated as they pass up the food chain

Pollution sediments on stream ecology
Pollution: Sediments on Stream Ecology 17

  • Loss of hiding-resting places for small fish.

  • Attached aquatic organisms scoured from the rocks and sand.

  • Poor light penetration

Nutrients and aquatic plants
Nutrients and aquatic plants 17

Nitrogen and phosphorus

Fresh water affected more by phosphorus

Salt water affected more by nitrogen

Many of these nutrients are found in water only because of human activity.


  • National Recommended Water Quality Criteria

  • EPA lists 167 chemicals and substances as criteria pollutants.

    • Identifies pollutants and then recommends concentrations for fresh, salt, and human consumption (fish and shel fish consumption).

Drinking water standards
Drinking water standards 17

  • Drinking water standards are stricter.

  • Drinking water standards and health advisory: set of tables updated periodically.

    • Covering 94 contaminates

    • Under authority of SWDA (safe water drinking act)


National pollution discharge elimination system

Addresses point sources and issues permits that regulate discharges from waste water treatment plants and industrial sources.

Environmental sciences towards a sustainable future chapter 17

Total maximum daily load

Evaluates all sources of pollutants entering a body of water, espaecially non-point sources, according to the water’s ability to assimilate the pollutant.

Wastewater management and treatment

Lesson 17.2 17

Wastewater management and treatment

History of waste removal
History of waste removal 17

  • Before late 1800’s: wastes were disposed of in the outdoor privy (or behind the nearest bush)

    • Frequently contaminated drinking water.

  • Late 1800’s excrements disposed of in the already existent storm water drains.

    • Floods and over flow sent wastes floating in the streets.

  • 1900 the first waste water treatment facilities were built. Gradually storm and waste water pipes were separated.

    • Storm drains are not sewers

Sewers 17

  • Most sewer bound materials are 99.9% water, 0.1% waste.

  • The pollutants of waste water are divided into four categories:

    • Debris and grit

      • Rags, plastic bags, course sand and gravel

    • Particulate organic matter

      • Fecal matter, food wastes, toilet paper

    • Colloidal and dissolved organic matter

      • Bacteria, urine, soaps

    • Dissolved inorganic matter.

      • Nitrogen, phosphorus

Waste water treatment facility
Waste water treatment facility 17

  • Preliminary treatment

    • screening of debris and settling of grit

  • Primary treatment

    • Water moves slowly through tanks, organic matter settles and is removed (raw sludge).

  • Secondary treatment

    • Live organisms break down organic matter to CO2, mineral nutrients, and water.

Activated sludge system
Activated sludge system: 17

Oxygen is added to the secondary-treatment system through an air-bubbling system. A mixture of debris eating organisms (activated sludge) is added to the water and is vigorously aerated. Organisms reduce the biomass of the organic materials.

Environmental sciences towards a sustainable future chapter 17
BNR 17

Biological Nutrient Removal

A secondary activated-sludge system added to remove nutrients and oxidize detritus. (added because of cultural-eutrophication).

Because this water is actually purer than the body of water that it enters, it will dilute the pollutants in the body of water, improving the quality.

Raw sludge
Raw Sludge 17

  • Gray, foul smelling, syrupy liquid with a water content of 97%-98%.

    • Pathogens are certain to be present.

    • Biologically hazardous

    • However, as a nutrient-rich organic material, it has the potential to be a good fertilizer if it is treated to kill pathogens.

      • Anaerobic digestion

      • Composting

      • Pasteurization

      • Unclear which will prove to be best and most cost effective

Anaerobic digestion
Anaerobic digestion 17

  • Bacteria feed on detritus in the absence of oxygen.

  • Sludge digesters turn the organic matter into CO2, methane, and water.

    • Biogas (2/3 methane gas product)

    • The leftover 1/3 makes a good organic fertilizer.

Composting 17

Used to treat sewage sludge.

Raw sludge mixed with wood chips or some other water absorbing material. It is then placed in long rows (windrows)that allow air to circulate. A machine turns the material, bacteria and other decomposers break it down turning it into an excellent humus-like material.

Pasteurization 17

  • Heated sufficiently to kill pathogens.

  • The product, a dry odorless organic pellet.

    • Used as organic fertilizer.

Alternative treatment systems
Alternative Treatment Systems 17

  • Individual septic systems

  • Wastewater effluent irrigation

  • Reconstructed wetland systems

    • Beaumont, TX

  • The waterless toilet

Septic tank treatment
Septic Tank Treatment 17

  • Aerobic digestion of solids in septic tank.

  • Flow of liquids into drain field for evaporation, infiltration, or irrigation.

Suggestions for maintenance
Suggestions for maintenance 17

  • Use caution when disposing of materials down the drain.

    • Can fill up or clog system.

  • Have system inspected regularly

  • Considering disabling garbage disposals

  • Keep heavy equipment off your field


Lesson 17.3 17


Aquatic plant life
Aquatic Plant Life 17

  • Benthic plants

    • Emergent vegetation

    • Submerged aquatic vegetation (SAV’s)

  • Phytoplankton

    • Green filamentous and single cell

    • Bluegreen single cell

    • Diatoms single cell

Nutrient enrichment
Nutrient Enrichment 17

  • Oligotrophic: nutrient-poor water

  • Eutrophic: nutrient-rich water

What kind of plants would dominate in

oligotrophic and eutrophic conditions?

Eutrophication 17

  • As nutrients are added from pollution, an oligotrophic condition rapidly becomes eutrophic.



Eutrophic or oligotrophic
Eutrophic or Oligotrophic? 17

  • High dissolved O2

  • Deep light penetration

  • High phytoplankton

Eutrophic or oligotrophic1
Eutrophic or Oligotrophic? 17

  • Turbid waters

  • High species diversity

  • Good recreational qualities

  • High detritus decomposition

Eutrophic or oligotrophic2
Eutrophic or Oligotrophic? 17

  • Low bacteria decomposition

  • Benthic plants

  • Warm water

  • High nutrient concentration

  • BOD

  • High sediments

Natural vs cultural eutrophication
Natural Vs. Cultural Eutrophication 17

  • Natural eutrophication

    • aquatic succession

    • occurs over several hundreds of years

  • Cultural eutrophication

    • driven by human activities

    • occurs rapidly

Combating eutrophication
Combating Eutrophication 17

  • Attack the symptoms

    • Chemical treatment

    • Aeration

    • Harvesting aquatic weeds

    • Drawing water down

Combating eutrophication1
Combating Eutrophication 17

  • Getting at root cause

    • Controlling point sources

    • Controlling nonpoint sources

Biological nutrient removal
Biological Nutrient Removal 17

  • Activated sludge: 3 zones

  • Conversion of NH4 to NO3

  • NO3 converted to N gas and released

  • PO4 taken up by bacteria and released with excess sludge