MABZI -- Water Quality Articals

	Water Quality
	THE ROLE Of CHEMICAL ANALYSIS IN WATER QUALITY:

During the latter part of nineteenth century, before bacteriological examination became accepted, the safety of water was evaluated by chemical methods. The relative concentrations of ammonia nitrogen, nitrates, nitrites, and albuminoidal nitrogen were used to indicate the presence and amount of recent pollutions. Water was considered to be safe when the predominant amounts of nitrogenous matter were in the oxidized forms. The use of such chemical tests to evaluate the bacteriological safety of water failed to prevent outbreaks of waterborne disease. With the acceptance of bacteriology procedures, together with increased knowledge of the role, which microorganisms have in causing diseases, bacteriological examinations replaced chemical analyses as the mean of determining whether water was free from disease producing organisms.

The time required to complete a bacteriological examination of water prevents direct utilization of this test in routine water plant operation. This deficiency is overcome at plants that disinfect the water with chlorine by use of residual chlorine analysis. By correlating the amount and type of residual chlorine in finished water with the results of its bacteriological examination, it is possible for each plant to determine the chlorine residual required to ensure production of water that is free, or essentially free, form coliform bacteria. The residual-chlorine test is undoubtedly the most important of all chemical analyses used to control the quality of drinking water.

Those concerned with the establishment of the first United States Standards. For drinking water were unable to reach an agreement on the health related aspects of physical or chemical parameters. The public health service standards for drinking water, 1914, specified bacteriological but not chemical or physical requirements. Limiting concentration for copper, lead, and zinc were included in the 1925 standards, and the 1946 standards contained seven additional chemical substances. The list of chemical substances whose presence in excessive amount are undesirable or even cause for rejection of water for drinking purposes was expanded in the 1962 standards.

For the user's point of view the term “water Quality” is used to define those chemical, physical, biological, or radiological characteristics by which he evaluates the acceptable to the user. If it is unsatisfactory, a treatment plant can be designed to produce acceptable-quality water. The term “Quality” must therefore be considered relative to the proposed use of the water. One might speak of water as being of poor quality, medium quality, or excellent quality when it comes to satisfying an individual.

Those involved in water quality needs are thinking more and more in terms of its multiple uses. The field of water resources is in a state of change as attempts are made to define the various qualities of water necessary for each of its much use. If one considers water from an abstract point of view and superimposes the problem of inadequate amounts of high-quality water, it seems quite logical to place all uses in order of their importance. Water for human consumptions also used for the lowest-level purpose that of flushing wastes to a point of disposal. There are major problems in providing separate water supplies for drinking and waste disposal. It is not feasible to construct a wall down the center our streams to provide separate channels, one for clean, unimpaired fresh water and the other for wastewater. This places other users of water, particularly one's downstream neighbors; in the position of having to contend with water, which has been used to, some extend by others.

Reuse of water, then, has become a necessity in many cases. This may be repugnant to many who think of used water only as reflecting an inherently distasteful quality as well as possibly having infectious characteristics.

On the other hand, water that falls from the sky is merely water, which has been evaporated, possibly from a polluted source elsewhere on the face of the earth. if we take polluted water and by evaporation, produce water as pure as rain, no consumer should object Even so. If it was a man-made and man operated process with sewage as the raw ingredient, this particular system would probably be objectionable to many. The Chanute and Santee experience indicates that the public attitude towards utilization of water can be changed. The public's concept of reuse and their emotional and hysterical reactions can be replaced by common sense and regards for scientific facts. Obviously, as our population grows, the need to reuse water will increase already there are cities using water from rivers whose contents have been many times by upstream consumers. This practiced is countenanced because the waste involved is discharge to a natural steam. Somehow, if nature intercedes, the resulting mixture becomes more acceptable. The city of Philadelphia , for example, utilities water that has been used by many villages and towns before it reaches the city of Philadelphia , where it is once again treated before being pumped to that city's distribution system.

The Neosho River that flows through the state of Kansas has a similar problem, which has been outlined very ably in the journal of the American Water Work Association. It is estimated that the various cities along this river use the total volume of floe from four to seven times during its passage through the state. During one drought period, the city of Chanute , Kansas , was on the average of having little or no water. Constructing a temporary earthen dam across the river to back the sewage plant effluent through a rather long lagoon up to the water plant intake. Therefore, the treated sewage was recalculated through the lagoon up to the water plant intake. The same water was treated and used an estimated six or seven times by the inhabitants of Chanute before the drought ended some 7 months later. Although this water was bacteriologic ally safe and available for drinking, it was not aesthetically satisfactory water.