Exercise 4

Read and translate the following word-combinations.

1. { liquid 2. sewage}

waste {solid preliminary } treatment

{ industrial primary }

secondary}

auxiliary}

3. disposal }

water-supply } system

hot-water }

Exercise 5

Choose the correct definition that best keeps its meaning in the right-hand column.

1. dense	a) the waste matter carried away by sewers
2.drainage	b) the size, number or amount of things
3. sewage	c) closely-packed; thick
4. quantity	d) the act or the manner of treating
5. treatment	e) a system of drains, artificial or natural

EXERCISE 6

Match an adjective in column A with a noun in column B

A		B
1	small	a	water
2	high	b	problem
3	difficult	c	wastes
4	pure	d	amount
5	solid	e	plant
6	industrial	f	standards

EXERCISE 7

Read the text and try to understand its content.

Water supply and removal of sewage

Man uses water for domestic and sanitary purposes and returns it to the source through sewage disposal system. Industry likewise replaces water diverted to its use. Hence the cycle is completed but it is of prime importance that the supply be protected against pollution, for it is fouls no one can predict how disastrous may be the results.

Every building should be provided with water, electricity, ventilation and heating systems. The water supply and sewage systems are called plumbing.

An adequate supply of pure, wholesome and palatable water is essential to the maintenance of high standards of health and provide the convenience modern society demands. In some localities water is available in unlimited quantities and converting it to use is not a difficult problem. This is especially true of towns situated on large inland lakes or rivers. On the other hand there are cities where geographical location requires elaborate systems of water supply, and to provide a satisfactory supply of water in these localities becomes a large engineering task.

The importance of a sufficient supply of water for domestic and industrial purpose has long been a deciding factor in the location of cities. Water may be taken from any sources of water for human consumption after it has undergone a preliminary treatment to assure its purity.

A water-supply system consists essentially of the following parts: a source of supply, which may be a lake, stream, spring or well; a reservoir for storing water for use during periods when demand is greater than the daily flow of water; conveying the water from the source of supply to the community is accomplished by means of a pipe line or a conduit; removing impurities from the water to make it suitable for use requires a treatment plant; and a distribution system of pipes is used for delivering the water throughout the various streets of the community.

Some systems are simpler and consist only of a source of supply, a main pipe line, and a small amount of distribution piping; others are more complicated and include in addition to the elements previously listed, distribution reservoirs, pumping plants, and other accessories.

Water in a low-pressure hot-water system is heated in the boiler, and consequently becomes less dense than the cold water in the higher parts of the system. The denser colder water sinks to displace the heated water, which is forced to rise. In this way, a circulation of water is set up- the process known as connection. The water rises up the primary flow (PF) into the hot-water storage cylinder or tank, and is replaced by water descending the primary return (PR). If a temperature difference is maintained between the water in the PF and that in the PR. then the process will continue. This is called the primary circulation.

The waste products that result from the daily activities in a community are of two general types: namely, the liquid waste, known as sewage and the solid wastes, known as refuse. The different wastes of which sewage is composed are the following: the wastes from lavatories .baths, sinks, and laundry ( tanks in residences, institutions, and business buildings; certain liquid wastes from various types of manufacturing or industrial plants. The sewage from residences, institutions and business buildings is called domestic sewage, sanitary sewage or house sewage, that resulting from manufacturing or industrial processes is known as industrial waste; and that from run-off during or immediately following storms is called storm sewage.

The removal of all kinds of sewage is usually accomplished by means of sewers. The sewers are placed in the streets at several feet below the ground surface. The general process of removing sewage is designated as sewerage and the entire systems of sewers including a sewage treatment plant is known as a sewage system.

The method of sewage treatment may consist only of the discharge of the raw sewage into a stream or a large body of water. The usual methods of sewage treatment consist of preliminary treatment alone or of primary treatment followed by secondary treatment.

An auxiliary treatment which may be used with either primary or secondary treatment is disinfection or killing of the most bacteria in the sewage by means of chemicals. At the present time the problem of good sanitation is closely connected with that of protecting the purity of natural water reservoirs, since often the same body of water must serve both as a source of water and as a recipient of sewage and storm drainage. And it is this dual use of water in nature and within communities and industrial premises that establishes the most impelling reasons for water sanitation.

Notes to the text:

sewage system - канализация

pipe line - трубопровод

pumping plant - насосная установка

storm sewage - сточные воды ливневой канализации