Page 13. Sludge density meter using nuclear radiation _ _ 14. Integrated water quality detection, recording and telemetering equip- 15. Improved basic apparatus for pH measurement_ 16. Schematic drawing of Hays dissolved oxygen analyzer. NEW MATERIALS AND NEW USES OF MATERIALS IN CONSTRUCTION OF WATER AND WASTE COLLECTION, DISTRIBUTION, AND TREATMENT SYSTEMS AND IN WATER QUALITY CONTROL INTRODUCTION MODERN WATER AND SEWERAGE SYSTEMS The present economic and community development of this country would have been impossible without the modern water distribution and sewage collection systems which serve the cities of the Nation. These utilities are vital in the support of large concentrations of people, commerce, and industry, and to our present high standards of living, health, and way of life. One can only speculate on what conditions of filth and disease would prevail in cities like Chicago, New York, or Los Angeles if there were no sewage collection systems. Without water distribution systems, present population densities could not be supported, fire protection would be incredibly difficult, and waterborne disease would be rampant as it was in the 19th century before the advent of the modern water purification plant. The new home of today, replete with multiple baths, automatic laundries and dishwashers, and garbage disposals, would be but an architect's dream. COST OF WATER AND SEWERAGE SYSTEMS As it is, the modern water distribution system delivers clean, safe water to the farthest point in the community and to the top floor of the highest building at an average cost of 17 to 19 cents per thousand gallons, or less than 5 cents per ton. After use, this water is collected by the sewerage system and conveyed away to a point of disposal at a cost averaging 4 cents per thousand gallons. In most cities the sewage is treated at least to some degree before discharge to a watercourse, and this service averages about 4 to 6 cents per thousand gallons. Water supply and sewage collection are the cheapest of all utilities, and so efficiently and reliably provided that the average consumer seldom realizes how dependent he is upon them. Although water supply and sewage collection systems are the cheapest of utilities, they represent collectively a very large dollar investment. The following table shows the investment requirements for municipal water and sewerage facilities for the period 1958-80: 1 Present and projected investment requirements for municipal water and sewerage facilities, 1958-80 1 Includes source development,'distribution systems, and water treatment facilities. In view of the magnitude of investments to be required within the next 20 years, it is essential that the design and construction of water supply and sewerage systems provide for the maximum service at the minimum cost. This will require a continuing search for new, more effective design criteria, construction materials, and procedures. Once in place, such systems require continuing operation and maintenance, with a need to develop the best chemicals, materials, equipment, and instruments to assure continuous service and to protect a very large investment that is largely buried underground. COMMUNITIES SERVED BY SEWERS Since 1900, the number of communities served by sewers has increased from 950 to more than 11,000, and the number of persons served by sewers has risen from 24.5 million to more than 105 million. In 1960 the municipal wastes discharged to streams had a pollutional effect equal to the untreated sewage from 75 million people, 3 times the amount in 1900. Pollution from water-using industries has increased even more. In 1960 organic industrial wastes were estimated to have a population equivalent of 150 million persons, and in addition there are large amounts of inorganic wastes (or mineral and chemical origin) not measurable in terms of sewage (as population equivalent). WATER USE AND NEEDS During this same period fresh water use has leaped enormously. Since 1900, it has increased eightfold-from 40 billion gallons a day to the present more than 325 billion gallons a day. By 1980 water needs are expected to reach 600 billion gallons a day, and by the year 2,000 the daily need will be well over 1,000 billion gallons. Since present water use already exceeds the developed supply in many areas, and 650 billion gallons per day appear to be the maximum dependable supply we can ever hope to develop, it becomes apparent that water needs can be met only by the reuse of the same waters. WATER QUALITY MANAGEMENT Both the increase in fresh water use and the increase in water pollution are a direct result of population and industrial growth. Obviously, increasing pollution is in direct conflict with the need to reuse water. This conflict must be resolved through the development of |