Page images
PDF
EPUB

is used for the water mains. The scheme is expected to be completed in 1974.

Yet another scheme which would go a long way to relieve the Bombayman's water plight is the Upper-Vaitarna scheme. This when completed would increase the daily supply by 120 million gallons. Work on this Rs. 42 crore scheme is reported to have started and is likely to be completed within. the next four or five years.

As a stop gap measure the utilization of the Ullhas waters is being strongly advocated. The scheme is estimated to cost Rs. 25 crores. Work on the scheme has started and it is very likely that by April 1967 an addi

tional 20 million gallons of water would be available from this source, if, according to the authorities, 'pump, and transformers were available in time.

Put together these schemes make impressive reading. This they have done over the years. For years after the blueprints were drawn and estimates expenditures made they have been put aside. This, while the citizens suffered.

It is no wonder therefore that the Bombayman is disillusioned by these plans. "What makes you think thess plans would be fully implemented," asked a water starved critic.

[merged small][merged small][graphic][subsumed][subsumed][merged small][merged small][merged small][ocr errors][merged small][merged small]

FRESH WATER FOR THE WORLD

Well over 2,000 years ago the Greek philosopher Aristotle recorded that fresh water could be distilled from the sea, but it is only in modern times that the enormous demands of industry and growing populations have made the desalination of water a matter of major importance. In a recent programme in the BBC World Service series 'Made in Britain', some experts engaged on desalination projects discussed various developments.

Over half the desalinated water produced in the world today is processed by British equipment. Dr. Hugh Simpson, a senior desalination research engineer, attributed this lead by a country until recently considered well endowed with water to Britain's interest as a maritime power in desalting water for use on shipboard, and to the fact that she had been associated with many dry and desert areas of the world. Today, her own • water shortage is becoming more serious each year owing chiefly to the demands of industry. To make one ton of steel, for example, requires 65,000 gallons of water, and one ton of synthetic rubber calls for 600,000 gallons.

The first steamships used the higher quality distiled water for their boilers, and carried shore water for domestic purposes. But in large modern passenger ships this is uneconomic and nearly all have desalination plant to provide fresh water for all purposes.

The first land plant was built for a mining village on the Red Sea coast in 1910, saidnarrator Michael Pickstock. "Based on marine evaporation, it produced about 16,000 gallons a day-insignificant compared with a single modern plant in Kuwait which can produce nearly one-and-a-half-million gallons a day. A complex of several plants provides the area with over three millon gallons of fresh water each day."

[blocks in formation]

then transferred to another chamber at

reduced pressure. This causes the process known as 'flashing'-a sort of instantaneous boiling producing a quantity of vapour which rises and condenses on cooler tubes. The brine, or heated water, goes into another chamber at a rather lower temperature and a lower pressure again, and the flash process is repeated. This can go on for as many as thirty stages, some water being flashed off as vapour condensed on the tubes at each stage. The cooling water in the tubes is heated up by the condensing steam and returns to form the brine passing through the flashing process, which makes for a very economical use of the heat put into the system.

Dr. Simpson said that the evaporation process was the most common and cheapest method in use today, and was likely to remain the most reliable for the next eight to ten years. But it had reached a stage of development where improvement was becoming increasingly difficult.

The second main of group processes, he explained, involved a change from the liquid phase-seawater-to the solid phase-ice; the third group consisted of membrane processes, "in which either the sodium and chlorine in the water are caused to pass through a membrane preferentially to the fresh water, or the fresh water itself is caused to pass through the membrane, leaving the salt behind. the former case is an example of electrodialysis in which the sodium is caused to pass through onemembrane preferentially while chlorine passes through another membrane preferentially under the action of an electric current; in the latter case we have the more recent process of reverse osmosis."

Only the evaporation and electrodialysis processes had been of any practical consequence so far, although freezing processes bad been studied extensively, and the reverse osmosis process showed promise.

All desalination processes need expensive plant and fuel, which makes the cost of the (Continued on page 31 )

[graphic][subsumed][subsumed][subsumed][subsumed]

DRINKING-WATER FOR ALL?

Everyone knows that India has a drinking-water problem. In the drought of the past summer newspapers were full of reports of wells running dry and the population of whole villages being forced to migrate. So desperate was the need in some ar as that special trains carrying water were held up and robbed of their precious supplies before reaching their destination. It was commonplace to hear tales of water being sold at Rs. 1 or more a bucket.

The 1966 summer may have been exceptional, but the same story is repeated in a lesser degree every year. There are just not enough wells-or not enough adequate wells-to supply the 360,000,000 people who live in the country's 559,000 villages.

(Continued from page 29 )

water produced considerably higher than that of reservoir water, which in Britain costs an average of less than three shillings per 1,000 gallons. The new method of using the steam which has already passed through the turbines of nuclear-powered generating stations may bring more competitive prices. Dr. Hans Kronberger, of the United Kingdom Atomic Enery Authority, said that fresh water could be produced at about four shillings per 1,000 gallons in the case of a fairly large gas-cooled reactor. That cost was still far too high for irrigation purposes, but was approaching a figure that would be of commercial interest for domestic and industrial use.

[ocr errors]

"Cheaper fuel and larger plants are two of the factors involved,' summed up narrator Michael Pickstock, "but a third equally important one is the design and construction of plant which is efficient and reliable to run. British equipment already enjoys a reputation in this field and to ensure that it is maintained and to examine new desalination techniques for the future, the United Kingdom Atomic Energy Authority and a leading British company are to co-operate in the running of an experimental station on the Ayrshire coast in Scotland."

How vast the problem is, is at present being investigated by the Ministries of Health and Community Community Development. Surveys carried out this year show that as much as a third of the total rural population still lack any organised supply of drinking-water. To remedy this state of affairs a total of Rs. 6,000 million is needed.

And this relates only to villages with no well or other all-the-year-round supply. It does not include the large number of other villages where supplies may be adequate but the water is impure. The surveys show that this is the case in 50 districts in eight States, in all of which the drinking-water supply is officially described as "generally unclean." it is no coincidence that cholera is endemic in these regions.

What is the government doing to improve the position? During the fourth plan it has allocated Rs. 1,250 million for work connected with supplying drinkingwater to villeges. It is estimated that by the endof the plan, 80 per cent of the population will have access to a supply of good drinking-water. In case this figure appears too optimistic, it must be remembered that the percentage refers to the country as a whole, including the 20 per cent who live' in towns and cities and already have-though they may dispute it-a "good" supply.

It is estimated that it will take two more another 10 years, before the plans, or remaining parts of the country are assured of adequate water.

India, of course, is not alone in having water problems. A recent survey conducted by the World Health Organisation has shown. that only 11 per cent of the populations in the 75 countries surveyed had "good" or "fair" water supplies. This leaves 89 per cent of the people with supplies classified as "unsatisfactory" or "grossly unsatisfactory."

It is further estimated that every year 500,000,000 people throughout the world suffer from disabling diseases asssociated with unsafe drinking-water.

A New Method Of Water Purification

By Oleg Kalinko

The main stage of water purification is its clarification and decolourization. These processes take place in large settlers where the water is freed from organic substances, suspensions and iron. All these particles settle in the form of flakes at the bottom. Purification prucess is completed in filters.

In settlers flakes are formed slowly. In winter the quality of purification is much inferior. In 3.4 hours the filters should be cleansed with the already purified water.

The scientists of many countries are working on water purification problems. Certain substances have been found, which accelerate and improve this process. New Intensificator-HSK

The research workers of the Kiev Insti

tute of General and Nonorganic chemistry of the Ukrainian Academy of Sciences suggested a new intensificator, called HZK. It is the same sodium rilicate but treated by cloroair mixture. This method has advantages because in every water supply line water is disinfected with chlorine. HZK's efficiency is not inferior to that of the best intensificators. It is active in winter, allows to improve the quality of water; to increase the cycle between the periods of the filters, being cleansed, to 34 hours; to decrease twice the size of settlers and to increase the rate at which the water passes through them.

HZK may be produced right on the water pipe. An automatic installation, (Continued on page 33 )

[graphic][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][merged small]
« PreviousContinue »