Wastewater treatment

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. Since technology in the water treatment field is evolving rapidly, an enhanced knowledge of fundamentals will permit the engineer or scientist to adapt more readily to new processes. In many cases, the design of water purification processes is based on empirical formulas and procedures.

The treatment of water and wastewater requires a variety of techniques and processes involving until 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 (BOD). The total BOD of aqueous industrial wastes is three times the total BOD of wastes entering municipal wastewater treatment plants. Over 90 % of the industrial BOD is generated by the chemical, paper, food, and petroleum industries. 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 level of toxic chemicals do not accumulate and become harmful.

As our standard of living advances, our demand for water accele-rates, we have to meet the needs of an increasing world population by irrigating more of the unproductive areas. These needs require a stewardship of our water resources to preserve water quality through wastes treatment and to ensure adequate quantities through recycle.

4. Answer the questions:

1. It is necessary to use newer treatment operations, isn’t it? Why?

2. What is the design of water purification processes based on?

3. What does the treatment of water and wastewater require?

4. What are the pollutant levels in wastewater often characterized by?

5. What is BOD?

6. What industries generate the major part of the industrial BOD?

7. What is the total solid content in industrial wastes if to compare with domestic wastes?

8. Why must heavier industrial use of the available water be accompanied by greater treatment?

5. Complete the following sentences using some active words and word combinations (see below):

1. To meet current water pollution standards, it is often necessary … the efficiency of conventional processes.

2. Technology in the water treatment field is evolving …

3. The design of water … processes is based on empirical formulas.

4. The treatment of … requires a variety of techniques and processes.

5. The major industrial users of water are the … of metals, chemicals, paper and petroleum.

6. The pollutant levels in wastewater are often characterized by solid ….

7. Our standard of … advances, so our demand for water accelerates.

purification, content, to improve, wastewater, manufactures, living, rapidly.

6. Retell the text using the scheme:

1. The headline of the text is…

2. The text informs on (deals with, dwells upon)…

3. At the beginning the author makes close study of

(considers)…

4. Then much attention is given to…

5. The text also tells about…

6. To sum up it should be noted…

Дата добавления: 2014-10-17