CURRICULAR CORRELATIONS

To develop an understanding of the interdependence of all organisms and the need for conserving natural resources

A relatively unpolluted environment is essential to maintain the quality of life on earth.

Ecology N1.00 To understand factors involved in maintaining an adequate supply of potable water

1.01 explain the concept of Eutrophication as a natural process and how it is changed by human activity.

1.02 list various organic and inorganic industrial wastes, their sources and explain their effect on water.

1.03 list various organic and inorganic agricultural wastes, their sources and their effect on water.

1.04 explain the effects of domestic sewage on water.

1.05 identify the steps necessary in the treatment of raw domestic sewage

1.06 identify non-point source pollution in the community.

1.07 identify the steps involved in the potable water treatment process.

1.08 describe the practice of deep well injection.

I. Eutrophication as a natural process and how it is changed by human activity
A. Natural eutrophication and succession
1. Lake formation
2. Algal nutritional requirements and growth
3. Bacterial decomposition and B.O.D.
4. Changes in flora and fauna
5. Lake to swamp to meadow to forest
6. Time scale for natural succession
B. Accelerated eutrophication
1. Sources of organic and inorganic material
2. Effects an algal growth and subsequent chain of events
3. Time scale for abnormal eutrophication
II. Organic and inorganic industrial wastes affect water.
A. Industrial sources
1. Paper mills
2. Food processing
3. Chemical manufacturing
4. Manufacturing and small businesses
5. Hospitals and research laboratories
B. Types of wastes
1. Solvents
2. Chlorinated organic compounds
3. Lead, mercury, silver and arsenic compounds
III. Organic and inorganic agricultural wastes affect water
A. Agricultural sources
1. Field, yard and lawn runoff
2. Feedlot runoff
3. Slaughter houses
B. Types of wastes
1. Fertilizer
2. Manure and urea
3. Insecticides
4. Fungicides and herbicides
IV. Domestic sewage affects water
A. Types of systems
1. Privies
2. Septic tanks
3. Municipal sewage treatment
B. Composition of domestic sewage
1. Organic material
2. Pathogens
3. Heavy metals
4. Detergents
V. Treatment of raw domestic sewage.
A. Pumped to the plant
B. Screened
C. Ground
D. Settled
E. Trickle filtered
F. Disinfected and released
G. Sludge treatment and disposal
VI. Non-point source pollution in their community
A. Identify sources
B. Locate and map sources
VII. Potable water treatment process.
A. Pumping
B. Filtering
C. Disinfecting
D. Storage
VIII. Deep well injection.
A. The Knox Aquifer
1. Where and what it is
2. Current use/Future use?
B. The mechanics of deep well injection
C. Migration of wastes
D. Where it's been done and is still done

COMPONENT OF SCIENCE: Science in Society

GOAL:

To enable students to demonstrate positive attitudes toward science in solving problems and making personal decisions about issues affecting the individual, society and the environment.

4.2 PERSONAL NEEDS - The application of science may be used to change the quality of life for the individual.

4.2c - Science solves practical problems but may create new problems and needs for an individual.

BENCHMARK: All factors must be considered when determining solutions to problems. A solution to one problem may create other problems.

CLASSROOM CONNECTOR

40-50 minutes

Poster or slide of a pond ecosystem showing food chain

Protozoan, spores, aerobic decomposition, anaerobic decomposition, methane, hydrogen sulfide, natural eutrophication, succession, sediments

How many of you spend time at a lake or pond during the year? (response) I want you to list two changes you've observed at a lake from one year to the next. (List these on the board, most will probably be short term changes, i.e., new buildings, water levels, water clarity, etc.) Most of us have observed some short term changes that occur. Today, we are going to learn about how lakes change over hundreds and thousands of years.

Natural lakes are formed when geologic forces like glaciers or earthquakes create a depression in the earth's surface. Rainwater, runoff and sometimes ground water fill the depression with water. The runoff water brings silt, rich in organic nutrients and minerals, into the newly formed lake. Wind-borne bacterial, protozoan and algal spores soon establish populations and form the base of a food pyramid which, in time, builds to support larger plant and animal populations.

As we learned in our study of the pond ecosystem, decay bacteria break down the remains of dead plants and animals at the bottom of the lake. In addition to these sediments, runoff from the surrounding land continues to supply organic nutrients and minerals to the lake ecosystem. Algae and decay bacteria thrive in the nutrient rich waters. Water lilies take root around the shallow edge of the lake, catching and holding sail. As they die and decompose, they add more nutrients to the lake bottom and over time, the lake becomes shallower.

As long as there is adequate dissolved oxygen in the water this decomposition is primarily aerobic. However, with the continued influx of silt and the build up of organic matter, the aerobic decay bacteria use up the oxygen and a different kind of bacteria begin to dominate the decay process. These are the anaerobic bacteria whose products of decay are methane (Swamp) gas and hydrogen sulfide which smells like rotten eggs. Perhaps some of you have smelled the foul smelling mud from the bottom of ponds.

Natural eutrophication is the adding of nutrients to an ecosystem, resulting in a decrease of available oxygen. It is the force that drives the succession from lake to forest. Fish and minnow populations give way to air breathing amphibians and reptiles.

Cattails and marsh grass become established in the shallow water and shade out the lilies. As the lake continues to become shallower, vegetation begins to grow throughout the shallow water and the lake has become a marsh.

As the marsh becomes drier, willow trees become established around its border. Over time other plant communities replace the site once occupied by the lake. It has become a meadow and eventually will become a forest.

This natural succession process may take anywhere from 500 to 10,000 or more years, depending on the initial conditions of the area.

(Have students write in their notebooks the answers to the following) In the succession from lake to marsh eutrophication causes what long term changes in (1) the amount of organic material and minerals present, and (2) the amount of dissolved oxygen present.

Have students make a series of drawings that illustrate the role of eutrophication in the succession from lake to marsh to meadow to forest.

This classroom connector addresses instructional objective 1.01.

Yesterday we learned about the succession from lake to marsh to meadow to forest. This gradual change was driven by the addition of nutrients to the water and the resulting decrease in dissolved oxygen in the water. Please write the name of this process on your paper.

We are now going to consider two ways that natural eutrophication can be accelerated, or sped up. Both of these ways involve the addition of nutrients to waterways by human activity. However, in one instance we overfeed the aerobic decay bacteria and in the other instance we overfeed the algae. The end result of either addition is a depletion in the amount of dissolved oxygen in the water and the resultant, suffocation of fish.

If organic matter, say, sewage or waste food from a cannery or erosion runoff from agricultural land enters a river it will be acted upon by aerobic decay bacteria. But in the process of decomposition these bacteria "demand" oxygen and use it up. The amount of oxygen that will be consumed when a biodegradable substance is decomposed in an aquatic system is called the biochemical oxygen demand or BOD. BOD is measured in milligrams of oxygen per liter of water.

Typical Biochemical Oxygen Demands

type of water pure water (no organic material) typical fresh natural water raw domestic sewage sewage after primary and secondary treatment

BOD (mg/1) 0 2-5 hundreds 10-20

Now pure aerated water (Saturated with air) contains about 8.4 mg of oxygen per liter. Raw domestic sewage with a BOD of 250 mg/l would require 250 divided by 8.4 or about 30 times as much oxygen as is available in pure aerated water. Hence, BOD is a convenient index of pollution by nutrients. The higher the BOD, the greater the pollution.

The second way to accelerate eutrophication is to overfeed the algae with fertilizer from agricultural runoff or with phosphate containing detergents. Phosphorus is a major component of fertilizer. Additions of fertilizers to waterways can cause an algal bloom (Population explosion). It may seem that an increase in algae would increase the amount of oxygen present in the water because oxygen is a product of photosynthesis. But too much algae in a body of water blocks sunlight from reaching algae deep in the lake. These algae die and become food for the bacteria which use up the oxygen while eating the dead algae.

Other factors such as temperature and the particular microorganisms present affect the BOD. But accelerated or cultural eutrophication due to pollution kills fish and can shorten the life span of a lake from millinea to centuries or decades.

Reelfoot Lake, in West Tennessee, is an example of a lake in which cultural eutrophication is taking its toll. The present lake was formed in the early 1800's by a series of gigantic earthquakes. Since then widespread deforestation and agricultural use of the land in the watershed that feeds the lake has contributed millions of tons of eroded topsoil to the lake. Optimists give Reelfoot Lake 200-300 years of life left, pessimists, no more than 50.

Accelerated or cultural eutrophication can result from feeding what two types of aquatic organisms? (Decay bacteria and algae) BOD stands for what? (Biochemical oxygen demand) The greater the nutrient pollution the higher or lower the BOD? (Higher) What affect would the use of a food disposal have on the BOD of sewage?

This classroom connector addresses instructional objectives 1.02, and 1.03.

Each of us have different ideas about what water pollution is and where it comes from. Close your eyes and visualize water being polluted. Write down a brief description of the scene you visualized. (Allow a few minutes and then write some of their examples on the board. Organize them into two categories; point and non-point, and two subcategories; deliberate or accidental.)

Today we are going to learn the difference between point and non-point sources and identify and map some of these sources in our community. The map we begin today will be added to as you discover more sources.

When we think of water pollution sources, most of us visualize an accidental spill from an oil tanker or a pipe spewing nasty stuff into a river or stream. Although accidents do happen, almost all water pollution occurs routinely and in most cases is even permitted by law. Point source pollution occurs when a factory or treatment plant discharges wastes into the environment. There is usually a pipe or smokestack from which the wastes are discharged. Non-point pollution occurs when runoff from a broad area disperses pollutants into the environment. For example, farm land runoff often contains fertilizers, insecticides, and herbicides as well as topsoil.

Some of the most noticeable point sources of pollution are industrial; chemical manufacturers, food processors, and paper mills. In the manufacture of chemicals, various solvents are used and many chemical wastes are generated. Although many factories and chemical plants include water purification systems in their plant operations, none are 100% effective. Hundreds of chemical contaminants make their way into rivers and streams.

At paper mills, logs are chapped into chips, which are then soaked and heated in caustic chemicals and pulverized to make wood pulp, contaminating large amounts of water. The pulp is cooked and rinsed of the pulping chemicals and wood wastes, contaminating even more water. Although treated, the waste water contains chemicals which contaminate waterways. Organic wood wastes in the waste water decompose consuming large amounts of oxygen and suffocating fish. Chlorine bleach, used in over 100 mills throughout the United States, combines with heat and phenol compounds (From wood) in the bleaching tower to make dioxins and other toxic chlorinated compounds called organachlorines. These toxins are released into the air and water when wastes are dumped. An average-sized pulp mill discharges between 35 and 50 tons of chlorine compounds each day. The pulp is pushed onto wire mesh, formed into paper, pressed, dried, and rolled out. In many cases, dioxins formed during bleaching remain in the final product.

Manufacturers and some small businesses use large quantities of water. Most of the water enters the municipal sewage system, carrying various chemicals and solvents. Hospitals and research laboratories contribute organic material, pathogenic agents, disinfectants, low level radioactive wastes and numerous chemicals to the municipal sewage system.

Most agricultural sources of water pollution are non-point sources. Fertilizers, insecticides, herbicides and fungicides are often present in the runoff from crop fields. Manure and urea are in the runoff from feedlots and stockyards. Even residential lawns, golf courses and parking lots are non-point sources of pollution.

Now that we have an understanding of the types of water pollution, let's map some of the point and non-point sources in our community. (Use Pl, P2, P3... for point source 1, 2, 3.... and NP1, NP2, NP3,... for non-point source 1, 2, 3 or color code them). Now, everybody find the locations) of our municipal sewage treatment plant output. Label it P1. (Next locate a non-point such as a golf course, shopping mall parking lot or residential area or farm land as NP1, NP2, and NP3,...). You may wish to maintain a master class map on a bulletin board during the study of pollution and add to it as students locate more.

Yesterday, we learned about two different types of pollution sources. Write down an example of (1) point source and (2) non-point source pollution. (response) In the real world, the effects of pollution are often noticed before the source has been located. Search the Internet for examples of point source and non-point source pollution.

This classroom connector addresses instructional objective 1.04.

We have located and mapped some of the point and non-point sources of water pollution in our community. Please get your maps out and put your finger on the location of our domestic sewage treatment plant. (If your community has more than one, have them locate the one that serves them.)

Today we are going to learn how domestic sewage affects water and to understand this we must know what's in it. After we learn what is in sewage then we'll consider how it effects it.

Raw domestic sewage includes everything that goes down the toilets or sink and bathtub drains in your homes, hospitals, schools, restaurants and many small businesses. (At this point have the class compile a list of everything they can think of that would be in sewage). A large portion of domestic sewage is water contaminated with organic material; food scraps from "disposals," toilet paper, a host of miscellaneous solids and feces containing various pathogenic bacteria.

Trace amounts of heavy metals like cadmium, mercury and lead are present in the environment. They are magnified or concentrated in the tissues of organisms as they make their way up the food pyramid. Most humans choose to eat high on the food pyramid (Animal products) and thus intake these in relatively high amounts. Much of these metals is eliminated from the body in feces and is therefore a significant part of sewage.

Along with all manners of detergents, shampoos, disinfectants, dyes and cleansers, many substances are illegally or improperly disposed of down the drain. Together, this almalgam contaminates vast quantities of fresh purified water and exacts a huge toll on energy for pumping and cleaning it up before reintroduction into the environment.

The effect of sewage on surface and ground water depends upon the type of sewage system and the water treatment efficiency of that system. Most domestic (Household) sewage in Tennessee is pumped to a municipal sewage treatment plant. In outlying areas, however, homes are often equipped with septic tanks. Although once a common sight behind country homes, the privy, or outhouse, is disappearing.

The privy is a glorified hole in the ground about four to six feet deep which after a period of use is covered with dirt and another dug. Care must be taken in locating the privy. Runoff or seepage from it must not contaminate drinking water supplies.

The septic tank is a temporary holding tank for household wastes. Waste water enters the tank at one end and flows through the tank slowly. Solids settle to the bottom where they are acted upon by decay bacteria which reduce their volume to a tiny fraction of what they were. This material is called sludge. The waste water that leaves the other end of the tank is nearly clear but is odorous and contains disease causing organisms and must not come in contact with drinking water supplies. It is disposed of in a subirrigation drain field.

Periodically the sludge must be pumped from the septic tank and disposed of. Laws regulating the method of disposal of this sludge vary from county to county. It may be applied to certain agricultural land or more often it is taken to a municipal sewage treatment plant for further treatment. The fact that it contains high levels of toxic metals and pathogenic bacteria warrants this careful handling. (A detailed description of the treatment of sewage is included later.)

Today we've considered the impact of sewage on water. Write down four items in sewage that increase BOD. Write down four items that make it a health hazard.

Invite a spokesman from the local water department to come and speak on water treatment in your community.

This classroom connector addresses instructional objective 1.08.

So far in our study of water pollution we have concerned ourselves with the contamination of runoff and surface water. Recall from our study of the water cycle that water also exists beneath the surface; underground. Write down the term that refers to the water that makes up the water table, well water and spring water. (Ground water)

Today we are going to examine deep well injection, a controversial practice that contaminates groundwater. Recall that groundwater is contained in porous rock and sand beneath the earth's surface. About half of Tennessee's groundwater occurs in a very deep layer of rock known as the Knox Aquifer. This aquifer lies at a depth of 3000 to 5000 feet below the surface and extends from the foothills of the Western Appalachians to the Ozark Mountains. Between the Knox Aquifer and the shallower aquifers from which we get water we use lies a dense rock subsurface. Contrary to popular belief, there are no truly impervious layers or rock formations to act as absolute barriers to prevent the upward migration of injected fluids.

In theory, the deep injection well works this way. A 6000 to 7000 foot deep well is drilled and lined with a protective casing from the surface down to below the dense rock layer. Toxic chemicals are then pumped down into the well under extremely high pressure so as to force them into the porous rock of the deep aquifer. After a period of use the well is plugged and the toxins are sealed in their deep grave. Smaller deep wells drilled around the sight monitor the migration of the toxins. It is the relatively low cost of disposal of toxic wastes in this manner that makes deep well injection so attractive.

Current regulations prohibit injection wells in East Tennessee because of the regional rock deformations. In the Valley and Ridge province of East Tennessee the rock strata are intensely folded and faulted. A rock formation that is encountered at 5,000 to 10,000 feet below the land surface might in all likelihood crop out at the surface a few miles away. Moreover, the very forces that folded the rocks also crushed and crumpled them such that the joints and fractures are relatively large. There can be no assurance that injected wastes will long remain in the subsurface.

Current regulations also prohibit injection wells in West Tennessee because of the geologic nature of the aquifers there and the high risk of earthquakes west of the Tennessee River. The shallow aquifers are of uncemented sand through which water migration is rapid and an accidental spill could contaminate very large areas of those aquifers.

At the present time we do not get water from the Knox Aquifer. For now, there is an adequate supply of water in the shallower aquifers and surface water. Write on a piece of paper two changing conditions in Tennessee that could force us to use the water in the deep Knox Aquifer. (Population increase, industrial and agricultural expansion, continued drought.)

Now that we know something about just what deep well injection is, let's consider the pros and cons. Search the Internet to build the case for each position.

This is the time this file has been accessed since 01/06/03.

The University of Tennessee at Martin is not responsible for the information or views expressed here.

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