Answer the questions to the text:

1. How could people compensate shortage of water in some areas?

2. What are the consequences of sharp increasing of water consumption?

3. What problems do people solve with the help of reservoirs?

4. Do reservoirs have beneficial effect in economy as well as in ecology?

5. What way can underground waters be applied?

 

11. Write a review to the text PROTECTION OF WATER. Use the phrases from Appendix I

Unit II

Reading: Wastewater Treatment

Speaking: Living Standards and Water Quality

 

Study the active vocabulary.

enhance	remove	clarify
demand n,v	removal	feasible
design n,v	wastewater	conventional
transfer	nutrient adj , n	ensure
assess	suspend  n,v	fulfill
preserve	treat	recycle n, v

2. Read and translate the international words. Mind the stress:

em´pirical a, adequate a, in´terpret v, ´optimize v, principle n, ac´company v, ´scheme n, con´trol v, ´colloid n, sus´pension n, co´agulate v, ´microbe n, pathogenic a, factor n, ´ballast n.

 

3. Translate these word-combinations used in the text WASTEWATER TREATMENT. Consult a dictionary if necessary.

Eutrophication of lakes, through recycle, solids content, pathogenic organisms, nonbiodegradable compounds, diluted streams, degree of treatment,

to measure (assess) water quality for.

 

Choose the right equivalent in the brackets.

Объяснение (interpreter, interpretive, interpretation,); обработка (повторное использование (useless, usage, reuse, useful, user); растворённый (dissolvent, dissolved, dissolving); непродуктивный (productivity, unproductive, productive), взаимозаменяемый (interchangeably, interchangeable, changeability), осветление (clarifier, clarified, clarification, clarity), предварительная обработка (treated, treatment, pretreatment).

 

5. Learn these useful word-combinations:

    to improve the efficiency of, a variety of techniques, the major industrial users, the pollutant levels, the levels of toxic chemicals, aqueous industrial wastes, municipal waste water treatment plant, through waste treatment and recycle, chemical impurities, solids content, can be removed by the addition of, water reuse, primary industry.

6. Read the text and answer the questions below:

WASTEWATER TREATMENT

Part I

To meet current and proposed water pollution standards it is often necessary to use newer treatment operations and to improve the efficiency of conventional processes. The treatment of water and wastewater requires a variety of techniques and processes involving unit operations, transfer processes, thermodynamics and reaction kinetics.

The major industrial users of water are the primary manufactures of metals, chemicals, paper, petroleum, and food products. The pollutant levels in wastewater are often characterized by solid content and by biochemical oxygen demand, which is a measure of the dissolved oxygen used by microorganisms in biological oxidation of organic matter. The total biochemical oxygen demand (BOD) of aqueous industrial wastes is three times as higher as the total BOD of wastes entering municipal waste water treatment plants. Over 90% of the industrial BOD is generated by the chemical, paper, food, and petroleum industries.

The primary metals industries together with these four industries contribute 90% of the solids entering industrial wastewater. The total solids entering sewage treatment plants from domestic wastes are less than one-half of the total solids in industrial wastes. It is apparent that heavier industrial use of the available water must be accompanied by greater treatment to ensure that the levels of toxic chemicals do not increase and become harmful.

Since our standard of living advances, our demand for water accelerates, we have to meet the needs of an increasing world population by irrigating more of the unproductive areas and fulfilling the demands for an even greater industrial output. These needs require close stewardship of our water resources carried out by chemists to preserve water quality through waste treatment and to ensure adequate quantities through recycle.

The characteristics of wastewater are broadly classified into physical chemical and biological according to the type of measurement test that has to be performed. The analyses range from the very specific quantitative tests usually applied for chemicals to the broad group tests applied for biological classes.

The most important physical characteristic of waste-water is its solids content as it affects the esthetics, clarity and color of the water.

The chemical impurities of wastewater can adversely affect the environment in many different ways. Although the nitrogen, phosphorous and dissolved solids can be removed by the addition of chemicals and by certain tertiary methods, they are not easily removed in a conventional plant. Soluble organics can deplete oxygen levels in streams, and give taste and odor to water supplies. Toxic materials can affect food chains as well as public health. Nutrients, leaching from agricultural land into water courses that can lead to algae blooms and eutrophication of water bodies. Although some chemical tests are specific, many determine broad classifications due to the variety of compounds found in wastewater. If water reuse is to be widely practiced, these materials will have to be removed.

Biological tests on water and wastewater determine whether pathogenic organisms are present by testing for certain indicator organisms. Biological information is needed to measure water quality for such uses as drinking and swimming, and to assess the degree of treatment of the wastewater before its discharge to the environment.

Many operations are used to purify water before discharge to the environment.

The main objectives of conventional wastewater treatment processes are reduction of biochemical oxygen demand, suspended solids and pathogenic organisms. In addition, it may be necessary to remove nutrients, toxic components, nonbiodegradable compounds, and dissolved solids. Since most contaminants are present in low concentrations, the treatment processes must be able to function effectively with dilute streams.

 

1. What is necessary to do in order to meet modern water pollution standards?

2.  What does the current treatment of water and wastewater require?

3. What are the major industrial users of this century?

4. What is BOD?

5. Where is wastewater treated? Do such plants treat all the industrial wastewater?

6. Why do the modern water consumption standards require close stewardship of chemists?

7. What are the possible ways to preserve water quality?

8. What are the most important characteristics of wastewater?

9. How do chemical impurities influence water quality?

 

7. Translate these terms used in the text WASTEWATER TREATMENT (Part II). Consult a dictionary if necessary.

Removal, settling, clarifier, thickener, tank, pretreatment, raw wastewater sludge, clarification, thickening, flocculate, coagulate, softening, stabilization, conditioning, dewatering.

8. Match the phrases in A with the corresponding word-combinations in B:

A	B
1. limited pretreatment	a. важное обстоятельство
2. mass transfer	b. реактор для обработки отстоя
3. important consideration	c. массопередача
4. sludge reactor	d. отстойники
5. settling tanks	e. ограниченная предварительная обработка

 

9. Read the text and arrange the items of the plan according to the information given in the second part.

1. The biological waste treatment.

2. Mass transfer in wastewater treatment systems.

3. The characteristics of industrial wastes.

4. Treatment processes for sludge.

5. Sedimentation process in the wastewater treatment plant.

6. Removal of solids.

 

WASTEWATER TREATMENT

Part II

INDUSTRIAL WASTES

a) Since industrial wastes have a broader range of characteristics than domestic wastes they are treated by a wider variety of processing schemes. Industrial wastes are more likely to contain toxic and nonbiodegradable components that require physicochemical treatment instead of biological one. In some cases industrial wastes are discharged to a municipal plant directly or after limited pretreatment. In other cases they are treated in a separate plant designed for the specific wastes.

b) Mass transfer is an important consideration in many wastewater treatment systems. In order to carry out chemical or biological reactions, it is necessary to transfer substances into or out of the wastewater, as well as to move them adequately within the water to control concentration differences. The material transferred can be as diverse as gases, liquids, ions, charged colloids, or suspended solids. However the rate at which these substances are transferred is the primary concern of the field of mass transfer.

c) Sedimentation is the removal of solid particles from suspension by gravitational settling. Sedimentation basins are often referred to as either clarifiers or thickeners. The terms clarifier and thickener are often used interchangeably in describing tanks for effluent streams from activated sludge reactors. Since both clarification and thickening occur in any sedimentation basin, both functions should be considered in the design.

d) In water treatment plants, sedimentation is used to remove readily settleable particles, flocculated or coagulated impurities, and precipitated impurities from softening operations. In wastewater treatment plants, sedimentation is applied to a variety of organic and inorganic solids from raw or treated wastes. Primary settling tanks are used to remove solids, from the waste stream entering the plant. Secondary settling tanks handle the solids in the effluent from a biological reactor.

e) The purpose of biological waste treatment is to convert complex molecules into simple products and biomass by using a mixture of microorganisms. Since successful waste treatment depends upon suitable biological activity, it is necessary to operate the system to encourage microbial growth.

f) Since direct land or water disposal of raw wastewater sludges is rarely feasible or acceptable, sludge treatment is usually necessary to reduce its volume and to make it less offensive. Selection of treatment processes for sludge depends upon the nature of the sludge, environmental factors, and ultimate disposal options. The various alternatives examined to select the major processes are concentration, stabilization, conditioning, and dewatering.

10. a) Get ready to discuss in small groups the following things:

Living standards and water quality;

Analytical techniques for the water quality tests;

Running water, its physico-chemical characteristics;

Local water bodies: analyses and monitoring.

b) Search the necessary information. Refer to the certain data, authors, scientific sources, using the phrases for both direct and indirect citation.

Model: As it is mentioned in the article “………” ,

The author tells about…

He says that…

Our analysts consider that “…….”

The latest data concerning……. illustrate…..

So, here we can read the following: “……”.

⇐ Предыдущая9101112131415161718Следующая ⇒

Поделиться: