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soap consumption and save expense in preparing boiler feed water is not justified in a public water supply of this type. The cost to steam generating plants for the treatment of boiler feed water to overcome the excessive hardness due to lime treatment is about equal to the additional taxes they would have to pay should the entire city supply be treated with caustic soda. This ratio would vary with local conditions in a given community. Laundries would generally be direct gainers by the caustic soda treatment, but, as their increased cost is small, there can be no justification in taxing an entire community for the benefit of a few. p The increased burden to the householder for caustic soda treatment would in most instances be about equal to the present soap waste cost caused by lime treatment. This ratio is, of course, governed by the individual use of water for washing purposes. As a considerable amount of soap is discarded in household use, any exact financial saving cannot be determined. Economic consideration necessarily based upon more or less indefinite data indicates that the great expense of caustic soda treatment is not justified to the municipality. The cost of treating water a t the plant to prevent corrosion, together with other costs to the consumer, is but a small fraction of the losses sustained should corrosive water be supplied.
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It is therefore believed that corrective treatment with lime produces a water of the most economic value to the most users. ACKNOWLEDGMENT The data given in Table I11 were obtained through the courtesy of A. A. Ewing, assistant superintendent of the Point Breeze Plant of the Western Electric Company. LITERATURE CITED (1) Bancroft, W. D., “Applied Colloidal Chemistry,” 3rd ed., p. 375, McGraw-Hill, 1932. (2) Baylis, J. R., J. A m . Water Works Assoc., 9, 408 (1922). (3) Briggs, T. R., J . Phys. Chem., 19, 2110 (1915). (4) Heyer, von, Tillmans, and Heublein, “Die Untersuchung uad Beurteilung des Wassers und Abwassers,” 4th ed., p. 40, Ohmuller u. Spitta, 1915. ( 5 ) Hopkins, E. S., IXD. ENO.CHEM.,25, 1050 11933). (6) Hudson, H. W., and Buswell, A. M., J . Am. Water Works Aasoc., 24, 859 (1932). (7) Powell, S. T., “Boiler Feed Water Purification,” p. 122, McGrawHill, 1927. (8) Snyder, Pauline, Thesis, Ohio State Univereity, 1927.
RECEIVED September 26, 1933. Presented before the Division of Water, Sewage, and Sanitation Chemistry at the 86th Meeting of the American Chemical Society, Chicago, Ill., September 10 t o 15, 1933.
Corrosion Inhibition by Lime Treatment Effect on Industrial Water-Consumption Costs SHEPPARD T. POWELL, 330 N. Charles St., Baltimore, Md.
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HE corrosion of water mains and service pipes resulting in “red water” has been a perplexing and costly problem in the operation of many municipal and privately owned water systems. Up to the present, the only relatively satisfactory method for inhibiting this condition has been the addition of sufficient quantities of lime to produce protective coatings on the inside of the mains and laterals of the distribution systems. The classical studies by Baylis, Hoover, Hopkins and other investigators has added greatly to our knowledge on this subject. The success of anticorrosion treatment by lime will depend largely on the intelligence of the operators in the proper adjustments to meet local operating conditions. Fundamentally the theory of protective coatings to inhibit corrosion is sound, and assured success will be forthcoming if the rate of scale deposition can be adequately controlled. The difficulty that was experienced in the earlier periods of treatment was due largely to a lack of adequate control procedure, and there are many instances where inadequate treatment has resulted in excessively costly operation. There are numerous instances where the pipe line deposits have built up to such an extent as to impose excessive pumping charges resulting from the diminution of the size of the mains. The ideal conditions for the prevention of corrosion by lime treatment is to secure an impermeable film of calcium carbonate and to adjust the treatment after the deposit has been produced so as not to dissolve the deposit already formed and to hold further deposition of calcium carbonate a t a minimum. To produce these conditions requires extensive experience and constant accurate control of the treatment. Without such control, inadequate treatment will result, placing a heavy burden on both the domestic and industrial users of the water supply SO treated.
Although many public water supplies now receive lime treatment to inhibit “red water,” little, if any, thought has been given to the economic phases of the problem. To most investigators and to water works officials generally, the availability of a method for controlling “red water” has been the impelling motive for inaugurating the treatment, irrespective of any detrimental effect resulting therefrom for service other than purely domestic. Wherever the cost of treatment has been given Consideration, the factors considered have been limited to the actual cost of chemicals used and to the capital investment for equipment necessary to apply the lime. Further, the savings resulting from the reduction in pipe renewals have been fully credited to the treatment. Financial losses to industrial users resulting from this form of treatment have been given scant consideration, although in some cases, especially where overtreatment has occurred, the burden on the industrial users has been very great. It is the purpose of the author’s comments merely to draw attention to these facts in the hope that, where such treatment is under consideration or now in use, consideration be given to the industrial consumer’s status. SCALEFORMATION Possibly the most direct and calculable losses from the industrial user’s viewpoint are those sustained by the increased scale-forming solids added to the water and the financial losses incurred in steam generation. These are tangible losses subject to accurate estimates. From a recent study in one plant it was demonstrated that lime treatment of the public water supply which was used for make-up water imposed an additional cost for treatment of $15.04 per million gallons of water used, or approximately $1500 annually for the plant in question. It is interesting to note in this con-
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nection that the amount of residual lime in the city water resulting from the anticorrosion treatment was only a halfgrain per gallon. The itemized losses a t the plant in question have been summarized in Table I. These figures are reliable, since the company maintains an accurate accounting system, but are probably lower than the actual losses sustained, since there are a number of intangible losses which may not be readily evaluated and, therefore, have not been given consideration in the figures reported. It is readily apparent that in a highly industrialized community, where large quantities of water are used tor steam generating purposes, the total annual losses may run into large figures.
undertaken. This study revealed the fact that continued use of the municipal supply would result in completely disrupting the process and would impose a great financial loss annually on the manufacturer. It was necessary to secure a new water supply requiring a capital expenditure of approximately $50,000. I n addition to this burden on the consumer, the water company lost several thousand dollars revenue annually by discontinuance of service to one of its largest consumers. Such cases are by no means rare but are seldom reported in discussing the merits and cost of lime treatment. The importance of this problem to industries was demonstrated in an experience in a highly industrialized textile community in the East within the past two years. ImmediTABLE1. SUXMARY O F INCRE.4SED COST O F OPERATION O F ately after the lime treatment of the public water supply ZEOLITE WATERSOFTENING DUETO INCREASING THE HARDNESS started, complaints were received from silk dyers. The O F THE CITY W A T E R ONE-HALF GRAINPER GALLON magnitude of the troubles resulting varied in different plants, ADDEDCOSTPER MILbut all appeared to be more or less seriously affected. The LION GALLONSOP BOILER FEEDMAKEUP major complaints resulting from the difficulties in the tin A. Increase in salt consumption $1.60 weighting of silk were due to the detrimental action of high B. Increased sodium sulfate required to correct the ratios 0.99 C. Fuel losses due to increased boiler blow-down 1.88 alkalinity, increasing the rapidity a t which the tin salt D. Cost of cit water required for increased zeolite deposited and thereby upsetting the normal functioning of backwasXing and boiler blow-down 5.48 E. Increased depreciation and maintenance 2.05 this process, Adjustment of the pH value of the water by F. Increased labor 3.14 acid treatment corrected the difficulty in some plants, but a t 15.04 other factories these corrective measures were difficult to Increased cost (disregarding items C , E, F) 7.97 adjust on account of specific local operating conditions. The ultimate solution of the problem was effected by furnishINCREASED SOAPCONSUMPTION ing all the industries involved, with water from another Possibly the greatest single financial burden on a com- supply which was not lime-treated. This procedure, howmunity from lime treatment is the increased soap consump- ever, was costly and required the construction of large industion resulting from the added residual lime in the treated trial water mains and the incurrence of other incidental supply. It is difficult to estimate these losses accurately, losses in making the necessary change from one water supply but even the most conservative calculation will demonstrate to the other. I n the final analysis, the matter reverts to the preferential that the cost of soap consumed is an important item and may not be ignored in evaluating the actual cost of anticorrosion rights of the domestic or industrial consumers. It must be conceded that the first duty of any water company, either prevention measures as now practiced by municipalities. Various investigators have shown that each part per privately or municipally controlled, is to furnish a safe water. million of hardness added to the water will increase the soap I n this respect the industrial consumers requirement should consumption from 0.07 to 0.3 pound per thousand gallons of be given secondary consideration. The desire to produce a water treated. Undoubtedly the figures in the upper range potable water should not be construed, however, as is so are excessive, and the actual amount is close to 0.15 pound; often the case, to mean that the industrial consumer has no this is the factor used in the author’s estimate. This figure rights and should be penalized unduly to meet the primary closely approximates the results obtained by the previous requirement. Careful analysis of these conditions in many authors who have established a figure of 0.13 pound. Assum- cases will reveal the fact that no attempt has been made to ing the average cost of soap a t 15 cents per pound, this would synchronize the divergent water specifications for the two amount to $360 per million gallons of water used for washing classes of consumers. The problem is difficult but not beyond purposes for each grain of increased hardness. It is readily equitable adjustment. It may not be corrected, however, apparent that in large communities such losses may not be if the industrial consumers’ requirements are completely ignored in a n intelligent estimate of the value of such treat- ignored and will not be relieved until there are made available comprehensive cost data on this form of treatment. Up to ment as i t affects the taxpayer. the present, the majority of technical papers which have been presented by various groups interested in the matter have FINANCIAL Loss DUE TO INCREASED HARDNESS almost entirely ignored the ultimate effect of such treatment The penalty imposed on industrial users will vary greatly other than to direct attention to the success of the treatment with the specific requirement of the processes affected. A in inhibiting “red water” and estimating intangible savings short time ago the writer was consulted by a large textile from predicted pipe losses. industry relative to the effect of the use of water from a municipal water supply where lime treatment for the pre- RECEIVEDNovember 8, 1933. Presented before t h e Division of Water, vention of “red water” is practiced. Difficulty in processing Sewage, and Sanitation Chemistry at t h e 88th Meeting of the American was encountered shortly after the correction treatment was Chemical Society, Chicago, Ill., September 10 to 15, 1933.
WORLDNITROGENSITUATION.Following two years of decreases, the world consumption of nitrogen advanced almost 13 per cent in the fertilizer year ended June 30, 1933, as comI;ared with 1931-32, according to the annual report of the ritish Sulphate of Ammonia Federation. The production in Chile decreased over 58 per cent, while the output in other countries increased by 12.5 per cent, making a net world increase of 5 per cent. The total nitrogen-producing capacity in the world at the
present time is estimated to be a proximately 3,460,000tons of nitrogen, exclusive of Chile. &e “manufactured nitrogen” industry of the world thus operated at an average of about 46 per
cent of capacity. Agreements with the most important Continental nitro enproducing concerns and a tentative agreement with the Chifean nitrate industry were concluded in July 1932, and as a result orderly selling was introduced into most of the world’s markets: these agreements have been continued for 1933-34.
