Practical Applications

of their sewage. The Kentucky state line ex- tends to the Ohio side of the river. Cincinnati is therefore dis- charging her sewage into Kentucky. “The U. S. Government is further complicating the matter by building a dam below the city in order to secure a 7-foot channel during low water. To construct this dam the Govern- ment will likely back the sewage to the point at which the city takes her drinking water, producing a pollution problem involv- ing three cities, two states and the U. S. Government.” No more valuable illustrations in this connection can be drawn than from our cities adjacent to the Great Lakes. The practice of municipalities of emptying sewage into these large natural 16 Chloride of Lime in Sanitation: water bodies, which also supply their drinking water, may not appear to be wrong in theory, the self-purifying bacterial activi- ties ultimately being overwhelming, but what are the facts? In Buffalo (November, 1911) B. coli were found in 5cc. samples, from the new intake on seven days, from the old intake on eleven days.“ In Toronto the water from Lake Ontario is bad, 5,000 bacteria per cc. are not uncommon, and of these 25% B. coli.* In Erie, Pa., the typhoid outbreak in the spring of 1911, with death rate of 170 for the first four months, had to be allayed by chloride of lime.“ Cleveland forestalled a similar catastrophe by installing a hypo- chlorite plant at Kirtland Street.¥5 In Chicago, which still discharges 30% of its sewage into the lake, the water is only fairly good, and sterilization became advisable at the 68th Street intake.4* Milwaukee, emptying its 60,000,000 gallons sewage into the confluence of the three rivers on the west shore of Lake Michigan acted (June, 1910) very promptly by installing bleach within a week.'# We also mention Minneapolis, where a recent typhoid outbreak was checked almost before it began. Besides, all supplies from the Great Lakes are open to chance pollution by steamers. Amount of Chloride of Lime Used for Sterilization of Water. The exact amounts of chloride of lime required for water from different sources, etc., vary considerably. The average quantity employed in most cases lies between 5 and 12 Ibs. per million gallons of water. New York City sterilizes the Croton water with 16 lbs. per million. Cleveland, with a supply of 100,000,000 gallons daily from Lake Erie, likewise sterilizes with 16 lbs. per million gallons. Even larger quantities up to 25 Ibs. have been employed. Also much smaller amounts, as in Milwaukee where they use 6 lbs., and in Pittsburg even 3 Ibs. in conjunction with slow sand filtration. For each water, the dose required must be determined on the Chloride of Lime for Water Purification. 17 basis of bacteriological trials. It is common practice to increase the quantity indicated, by 25 to 50%, especially when the chloride of lime is added to the unfiltered water. This has been found the better way in order to guard against sudden fluctuations in the quality of the untreated water. Differences of Treatment Between Filtered and Unfiltered Waters. Water contains, aside from bacteria, organic matters which claim some of the chloride of lime added for oxidation, and thereby detracts from the efficiency of its sterilizing powers. In line with this, it is well known that turbidity reduces the efficiency of the bleach treatment; also that the total organic content of an unfiltered water has been reduced (oxidized) by 10% (in the case of Harrisburg), the products of such oxidation naturally remaining dissolved in the water. It has therefore become the more frequently accepted practice in plants where water is filtered to add the chloride of lime to the clear filtered water. In the following we give examples of the use of chloride of lime in a number of American communities, in conjunction with raw and with filtered waters: Some Cities Where Chloride of Lime is Used with Natural, Other- wise Untreated Water Supply. New York City has recently installed a sterilization plant at Dunwoodie, to treat the Croton supply of 380,000,000 gallons of water daily. The ratio is stated as 16 Ibs. per million gallons.'! Jersey City has used this treatment since 1908, for the water from the Boonton reservoir. Ratio, 5 to 8 Ibs. per million gal- lons. (In 455 samples taken during a period of 62 days, only one case with B. coli was found.)5 Council Bluffs, Iowa. Introduced chloride of lime in April 9, 1910, to allay a serious outbreak of typhoid. No cases of fever were reported during May. Brainerd, Minn. Operated the hypochlorite plant since October, 1910. The water supply from the Mississippi is now free from typhoid contamination, 18 Chloride of Lime in Sanitation. Erie, Pa. Since the installation of chloride of lime treatment on March 15, 1911, using 7 to 10 Ibs. per million gallons, bacterial count has gone down from an average of 234 to an average of 6.6 per cubic centimeter. Montreal. Since 1910 the whole water supply has been steril- ized with chloride of lime at a ratio of 5 to 74 Ibs. per million gallons, reducing the typhoid death rate as follows:4*™* Cases Deaths 1909 1910 1909 1910 68 27 8 November. se 50 19 13 December...... ae 52 42 29 Milwaukee. The sterilization plant installed as a result of a serious outbreak of typhoid in 1910, uses 6 Ibs. of chloride of lime per million gallons.'# Cleveland. An installation for sterilizing 100,000,000 gallons of lake water per day has been recently completed. The ratio is 16 lbs. of chloride of lime per million gallons.'” Among the cases of applying sterilization to spring water are Ridgwood, N. J. Corning, N. Y. Chloride of lime is used in connection with coagulation and sedimentation, without filtration, at Omaha, where the results are stated: Bacterial reduction in coagulated and settled water... .93.30% Bacterial reduction in coagulated and settled water, and bleach treatment... ... 2.2.06... cece cece eee e eee 99.85 Ratio, 74 lbs. per million gallons. Nashville, Tenn. The water of the Cumberland River is treated with 14 lbs. per’million gallons. Council Bluffs. The very turbid Missouri River water is treated by chloride of lime (15 Ibs. per million gallons) in addition to alum precipitation.15¢ Grand Rapids, Mich. The new purification plant of 20,000,- 000 gallons capacity provides alum precipitation with chloride of lime treatment,'4° Chloride of Lime for Water Purification. 19 Some Cities Where Chloride of Lime is Used in Connection with Filtration Plants. Little Falls, N. J. Uses chloride of lime with after-filtration. Harrisburg, Pa. Uses chloride of lime combined with alum coagulation before filtration. The high bacterial efficiency of 99.94% is reported. Ratio 9 lbs. per million gallons.‘#¢ Baltimore County Water Works Company. Here chloride of lime is added before filtration. It has been found to lessen cost of operation by reducing the quantity of alum used and to lengthen the filter runs. The water is practically sterile. Ratio 124 Ibs. per million gallons. Cincinnati, Ohio. Thanks to this treatment, ranked most favorably in typhoid rate (5.7), in 1910, among larger American cities. The ratio of chloride of lime used is 5-12} lbs. per mil- lion gallons.“ Toronto, Ontario. The new sand filters, put into service January 4, 1912, showed*° during April: Bacteria in raw water. szusnieee Bacteria in filtered water. - 815 After sterilizing. . (6 Ibs. of chloride of lime used per million isan) Niagara Falls. Two new water purification plants have been put into operation since the beginning of 1912, respectively, by the municipality and by the Western New York Water Com- pany, using coagulation with rapid sand filtration, and follow- ing disinfection. Typhoid Cases. January . 28 February. 12 March... May... June... July.. Minneapolis. The new plant under construction provides 20 Chloride of Lime in Sanitation. for sterilization with chloride of lime after mechanical filtration of the Mississippi River water.'«¢ Pittsburgh. Chloride of lime is used in connection with slow sand filtration. Mr. Johnson states that an increase in efficiency has followed its use. Usually not more than 3 Ibs. per million gallons has been required.® #8 %8 Rahway, N. J. Uses it in combination with pressure filters. A recent epidemic of typhoid was promptly cut short by its introduction. The ratio of 25 lbs. per million gallons was used, and not at any time detected by the consumer. Hackensack Water Company, which supplies water to about 25 communities, uses chloride of lime.“ Ottumwa, Ia. The new plant recently put into operation uses coagulation in conjunction with rapid sand filtration, followed by sterilization.'5* From the foregoing it will be seen that wherever municipal water supplies are naturally very clear or become so by com- pounding and sedimentation they can be made perfect drinking waters by the use of chloride of lime, and that in cases of turbid waters this valuable agent fits in with every established puri- fication device. To quote Professor Winslow’s statement (1910), “the process adds a great third to the two recognized present methods of water purification, namely, filtration and storage.” It also must be concluded that most small communities not provided with filtration or storage will have no choice but to adopt this most valuable sterilizing agent, even with somewhat turbid waters. Taste and Odor. Frequent trials have been made to define the maximum limit for chloride of lime in drinking waters. Speaking in general, amounts not exceeding 25 Ibs. per million gallons could not be detected by the senses. This was found in trials with Lake Ontario water at Toronto, where many of the “positive” results were observed to rest on auto-suggestion, belonging to “blanks” inserted in the trials.®** Complaints were received at Toronto Island early in 1911 Chloride of Lime for Water Purification. 21 when the rate was 5 Ibs. per million gallons, and entirely ceased later in the season when the rate was increased by 150%. At Rahway, N. J., 25 lbs. per million was not in any case noticed by the consumer. No reliable evidence has ever been produced that this steriliza- tion has any but the most beneficial influence on health; state- ments to the contrary must be treated as myths. Professor Heulett testified in the Jersey City case that in his opinion if 10 Ibs. of chloride of lime was added to one million gallons of Boonton water, any trace of free chlorine get- ting into the treated water would be equal to what has been cal- culated to become a medicinal dose if a person would drink one gallon per day for 7,180 years. Any doubts that could linger in the layman’s mind, may be dispelled by stating that the U. S. Dispensatory recommends the use of from one to two ounces of chloride of lime for treating 65 gallons of drinking water on board ships. This amounts to fully 200 times in excess of the usual amounts now employed in municipal water sterilization. That so many cities have benefited by water sterilization, is to be credited to the perfection and certainty to which the process was developed at Bubbly Creek. In addition, a most thorough verification of all the chemical facts involved has marked the first year of the working at the Jersey City Water Works Company at Boonton, where Mr. Johnson codperated with Dr. Leal in establishing the first sterilized water supply for an entire city, installed in consequence of a lawsuit over the quality of the impounded water from the Rockaway River. The decree of the court says, “I do therefore find and report that this device is capable of rendering the water delivered to Jersey City, pure and wholesome and is effective in removing from the water those dangerous germs which were deemed by the decree, to possibly exist therein at certain times. Upon proofs before me, I also find that the solution described leaves no deleterious substances in the water.”!77 For an exhaustive statement of the chemistry involved, the following passage’”* from one of numerous papers by Dr. Leal could not be surpassed: 22 Chloride of Lime in Sanitation. “Although the process is not by any means an entirely new one, yet it can be justly claimed that during our investigations and experiments in connection with the subject, much has been learned that was not before thoroughly understood and many facts have been proved which previously had been only theories. The most important of these are as follows: “(1) That bleach on being added to water ceases to bleach and therefore that criticisms which had been hitherto applied to such addition were without foundation. “(2) That on the addition of bleach to water the loosely formed combination forming the bleach splits up into chloride of calcium and hypochlorite of calcium. The chloride of calcium being inert, the hypochlorite acted upon by the carbonic acid in the water either free or half bound, splits up into carbonate of calcium and hypochlorous acid. The hypochlorous acid in the presence of oxidizable matter gives off its oxygen; hydrochloric acid being left. The hydrochloric acid then drives off the weaker carbonic acid and unites with the calcium forming chloride of calcium. “(3) That the process was wholly an oxidizing one, the work being done entirely by the oxygen set free from the hypochlorous acids in the presence of the oxidizable matter. “We have used during our investigations, the term ‘potential oxygen’ as expressing its factor of power. When set free, it is really nascent of atomic oxygen and is, in its most active state, entirely different from the oxygen normally in the water. “(4) That no free hypochlorite or hypochlorous acid would be left in the treated water in the presence of oxidizable matter. It is true that at times in the treated water at Jersey City, we have been able to get the reaction for so-called available chlorine, according to the method of Wagner, as modified by Schultz, there being always oxidizable matter present in such water, and it has been a matter of a good deal of discussion as to the true explanation of this. In my opinion, however, the matter has been definitely settled by the experiments and findings of Prof. Franklin C. Robinson of Bowdoin College, who first found such reaction in untreated Boonton Reservoir waters. It is but natural then, to conclude that this test for so-called available Chloride of Lime for Water Purification. 23 chlorine is simply a test for an oxidizing agent present in the water, be that what it may. “(5) That any of the atomic oxygen left after the first action, by which the more easily oxidizable substances aré destroyed, unites with those not so easily oxidizable and more slowly accom- plishes the same results. “(6) That no free chlorine could possibly exist in the treated water, the existence of free chlorine being impossible in an alka- line solution. “(7) That there could be no material change in the quantity of water after treatment, such as would in any way interfere with its use for potable and manufacturing purposes. “(8) That it could in no way injuriously affect piping, fixtures, ete. “The atomic oxygen set free from the hypochlorous acid seems to have a selective action upon the intestinal bacteria, as has been established by a long series of experiments by different observers.” From the foregoing and further facts, the nature and limita- tions of this process become clear. “Free chlorine” never is present. Chloride of lime used in such small quantities will kill bacteria but will not purify organic matter, nor cure discoloration, turbidity or moory and tarry smells in raw waters. The infinitesimal quan- tities employed for this are far too small, and for the defects mentioned, the other methods, as sedimentary coagulation and filtration are employed in conjunction with chloride of lime. Of the remarkable germkilling powers of chloride of lime, the statement that for water sterilization the ratio is one to one million may convey a picture less real than that three grains of a practically harmless substance, will kill the myriads of germs con- tained in a barrel of water. To do the same work with the poison- ous corrosive sublimate would require at least one ounce, or of the equally poisonous carbolic acid, five pounds! We show in the following tables two other aspects of the action of chloride of lime when strongly handicapped by presence of organic matter.