our nal - militaryhealth.bmj.comBleachmg powder, water -sterilizing powder, tropical bleach and tI chlorosene" are all easily transportable and, with the exception of bleaching powder,

VOL. LXI. SEPTEMBER, 1933.·

Authors are alone responsible for the statements made and· the opinions expressed in their papers.

~ our nal

®riginal (tommunicattona.

No. 3

NOTES ON THE CHLORAMINE TREATMENT OF WATER.

By MAJOR S. ELLIOTT, B.Sc., F.I.O., F.O.S.,

Analyst; Royal Army Medical College.

(1) HISTORICAL SURVEY.

As far back as 1907 a Germari chemist, Rachig [1] described chloramines and gave a method for their preparation. This was regarded as a piece of academic research and was not put to any practical use. Three years later Rideal [2J tried to purify sewage by treatment with chlorine, and found that after the whole of the chlorine had disappeared, a germicidal action continued. He knew that the sewage contained ammonia and so he ascribed the action to the formation of chloramine. In America, Race [3J experimented in 1915 on the treatment of water supplies with chloramine made by mixing two parts of chlorine to one part of ammonia in solutions not stronger than 5,000 parts per million . . He found that this substance, unlike chlorine, persisted in the water, and that it had a powerful sterilizing effect quite equal to chlorine. So efficient ·was the substance that it reduced the organism!? to between 10 and 0'3 per cent of the numbers originally present in the water. He then tried it on a large scale with the Ottawa supply where he used a mixture of chlorine solutIOn 0'3 to 0'6 per cent and ammonia solution of about equal strength, and in his book [4] he stated that good results were obtained. For some reason or, other, the matter was not pursued further, until in 1924 Harold and Ward [5] reported on their experimental work at the Army School of . Hygiene, Aldershot, and after that many observers commenced investigations and published their results. Harold and Ward [5A] working

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162 Notes on the Ohloramine Treatment of Water

entirely with the Army water-cart, prepared their chloramine by mixing in a kettle ammonium bicarbonate and chlorine water. This chloramine they then added to the bulk of the water to be sterilized. The chlorine water they prepared by charging water in a Sparklet syphon with compressed chlorine gas. They claimed that chloramine persisted in dirty water and retained its germicidal activity, that it had less taste than chlorine and that it was a vast improvement on chlorin€ for the treatment of water supplies.

1n'1926, Adams [6] reported on some experimental work on waters from wells in the chalk, using small doses of chlorine with various proportions of ammonia acting for several hours. He found that if the concentration of the mixture was over ten parts per million using bleaching powder or 1,000 parts per million when chlorine gas was used, there was a considerable loss of available chlorine, and therefore a loss of germicidal power. He also found that ammonia was more effective as a tastepreventer than the salts of ammonia, and that there was also less taste with chloramine made according to Harold and Ward's method than when chlorine and ammonia were mixed in the bulk of the water. His results, however, showed that there was practically no difference in sterilizing activity between chloramine made by Harold and Ward's. method and that made in the bulk of the water.

In 19:28, Harold [7] advocated the use of preformed chloramine. prepared as in his 1924 experiments, and noted that dirty water destroyed chloramine to a slight extent. In the same year some experiments on the treatment of swimming-bath water [8J were' published, chloramine again proving superior to chlorine and not being destroyed by tropical sunlight. It was found that a concentration as high as two parts per million was quite unnoticeable, but it was decidedly slower than chlorine in its sterilizing action. Methods were also given for the determination of chlorine and chloramine in the presence of each other. '

The germicidal effect on cercariffi in Egypt was reported upon by Griffiths-J ones, Atkinson and Hassan in 1930 [9]. They found that chloramine prepared in greater concentrations than 25 parts per million before addition to the water was not stable. They concluded that one part of chloramine in tap-water or two parts per million in the raw water of the River, Nile, in ratios of two parts of chlorine to one of ammonia, killed cercadre in one hour.

In 1932, Berliner [10J described the preparation and properties of strong solutions of chloramine and referred to SOme work done by Chapin in 1929 [l1J. The latter found that lllixtures of cblorine and ammonia in very acid solutions (pH 4'4) yielded nitrogen trichloride, in less acid solutions (pH 5'0 to S'5) mixtures of mono- and di-chloramines were found, and in alkaline solutions (pH over S'5) mono·chloramine was produced.

The Annual Reports of the Metropolitan Water Board for the last few years give records of the use of small doses of chloramine acting for


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.S.Elliott 163

long periods. The results show very efficient sterilization and no troubles due to taste.

Chloramilles are chlorine compounds of a.mmonia (NHs) in which one or two of the hydrogen atoms are substituted by chlorine forming respectively mono-chloramine (NH2Cl) and di-chloramine (NHCI2).

Further substitution produces nitrogen trichloride (NCls), a dangerously explosive chemical. In concentrated solutions they all decompose to nitrogen, ammonium chloride and other products.

Experimental work has recently been carried out at the Royal Army Medical College on the prepar9,.tion and properties of chloramines in order to fill in gaps in the present knowledge .of these substances, and to make clear the treatment of water with them to officers, of the Corps who have not the necessary time and opportunity to study the question beforehand.

(2) THE PREPARATION OF CHLORAMINE.

Materials Required.-(a) Ammonia. Ammonia gas from cylinders may be used and introduced. into the water through suitable apparatus. Care must be taken to keep the ammonia gas away from the chlorine gas or bleach until they are mixed in dilute solution, on account of the risk of forming the dangerously explosive compound, nitrogen trichloride.

Ammonia solution (specific gravity 0'880) may be used, but it is inconvenient to handle OIl' account .of its pungent odour.

The salts of ammonia, the chloride or sulphate, are the most convenient for portable plants, store we~l if kept dry and can be made into tablets if required. They do not evolve any fumes. of ammonia and if dry are non-corrosive. The bicarbonate has been used, but evolves fumes of ammonia and its composition is apt to alter. The chloride contains one third of its weight of ammonia and the sulphate one quarter, arid both can be obtained almost anywhere, the chloride being ordinary sal-ammoniac ann sulphate being used as a fertilizer.

All these sources of ammonia are equally efficient as shown by Tables I and lA and by Harold and Ward's results; Most waters are sufficiently alkaline to. liberate ammonia from its salts or the dilution is so great that the salts are ionized thus ensuring that free ammonia is present in the water.

(b) Chlorine .. Chlorine gas from cylinders may be introduced into the water through apparatus similar to that used for ammonia gas, but as the cylinders and apparatus are heavy, this system is better suited for large installations than for portable plants.

Bleachmg powder, water - sterilizing powder, tropical bleach and tI chlorosene" are all easily transportable and, with the exception of bleaching powder, are stable in' good storage. Tbey are all effective as vehicles for chlorine provided the percentage of available chlorine is known and remains reasonably high. This must of course be previously estimated. The correct dose required is easily measured out by means of small spoons


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or scoops, but as bleaching powder is lighter than the others, the scoop used for its measurement should be slightly larger. Unfortunately, these substances cannot be made into satisfactory tablets with. or without binding materials, as the tablets disintegrate on storage.

Sodium hypochlorite solutions can be made by the electrolysis of salt solution (five per cent) between Acheson graphite electrodes with a current density of about one ampere per square inch of surface at four volts. So long as the temperature of the solution is kept below blood-heat all is well, but as the temperature rises above this, chlorate begins to be formed, and as it· has no sterilizing power, it is useless for water purification. Hypochlorite made in this way is just as effective as the above forms of chlorine.

The'_ Preparation.-preformed chloramine is made by mixing the chlorine and. ammonia solutions together and. adding the mixture to the water to be treated.

Bulk-formed chloramine is made by adding the ammonia solution to the water to be treated, and when it has been distributed evenly, the chlorine solution is then added.

There· are three things to .. be considered in the preparation of chloramine :-

(i) The weight of ammonia and. chlorine to be used. (ii) The concentration of the solutions of ammonia and chlorine before

mixing.

(3) THE METHOD OF MIXING.

(i) The Weight of Ammonia and Chlorine to be used. In Tables I, lA, IB, 1I, lh and lIB it will be seen that the best ratio

of weights to use in order to form chloramine practically free from chlorine is four or less parts of chlorine to one part 'of ammonia. lithe ratio of chlorine rises to six parts, then a considerable part exists as free chlorine and is subjeCt to destruction 'by dirt in the ordinary way. With higher ratios of chlorine, an even larger proportion exists as free chlorine. -On the' other hand, a low ratio of chlorine forms a slower acting type of chloramine, as shown in Tables Ill, IlIA, IV A, lVB, etc.

The ratio of four parts of chlorine to one part of ammonia by weight gives a quick-acting product free from serious' deviation. It is very rare for a natural water to contain sufficient ammonia to upset these ratios, so the ammonia in the water may normally be neglected.

(ii) The Concentrations of the Solutions before Mixing. In the case of " bulk-formed" chloramine the concentrations of the

ammonia and of the chlorine solutions do not matter, of course, as they will be diluted down to One or two parts or less per million before they are mixed. It was found that the concentration of the chlorine solution which is added to the water already containing the ammonia had no effect·on the amount of chloramine formed; a strong solution ·formed the same relative proportion of chloramine as 11 weak one~ .


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S. Elliott 165

On the other harid, 'if .U preformed" chloramine is to be used, then the strengths of the ammonia and chlorine solutions are of vital importance. In the remarks on Table II it will be seen that a delay of five minutes after mixing and before adding the mixture to the water, in the case of a concentration of 25 parts per million, was of little consequence. In Table HA when the concentration· was 100 parts per million a five minutes delay caused a considerable loss of chlorine; and in Table lIB where 1,000 parts per million were used nearly all the chlorine disappeared in five minutes. Hence it is necessary when using this method of making chloramine to use concentrations of ammonia and chlorine· of less than 25 parts per million, or else if stronger solutions are to be used the·addition to the water must be made immediately after mixing ... In designing apparatus care must be taken to see that no dead spaces exist where the mixture can stand for any length of time before addition to the bulk of the water.

(iii) The Method of Mixing.

Bulk-formed Ohloramine.-rrhe only precautions necessary are that the ammonia should be dissolved and then evenly distributed before the chlorine is added, and tpat the ammonia should be added before the chlorine. Raw Thames water at MiIlbank containing about one part per million of free and saline ammonia destroyed 0'4 part per million of free chlorine in five seconds. When ammonium'sulphate was added first the destruction was not so serious; compare the" initial concentrations" in Table V where the same quantity of chlorine solution was added to tap-water, and to raw and filtered Thames water.

Preformed Chloramine.-The precautions to be taken are only tbose in connection with the concentrations of the solutions of ammonia and· chlorine as pointed out above. No differences were obtained between mixtures in which the chlorine was added to the ammonia, or the latter added to the former.

The problem arises-which of these two methods of mixing should be chosen?

As will be seen from Tables IIIA and IIlB, preformed chloramine has an advantage in cases where doses of less than about three-quarters of a part of chloramine per million is used in that it appears to have a more rapid sterilizing action than. the bulk-formed type. The mechanical difficulties of making preformed chloramine in a main can be easily overcome by inserting a small bore mixing pipe in the water main. .For Army purposes; however, where doses of one or more parts per million. are used, the bulk-formed chloramine is simpler to make and is equally effective, as is shown in Tables IV, IVA, etc. Chloramine made by the preformed method, especially when the ratio of ammonia is· high, contains a substance which gives what Major Harold terms "a second fraction." In the ordinary determination of chloramine, potassium or other iodide and starch are added to the water containing the chloramine.:. A bluecolour.is formed and the


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addition of sodium thiosulphate in qllantities just suffiCient to discharge the blue colour can pe made to give the strength of chloramine in the water. The colour having been discharged, if acid is now added to the water a blue colour again appears and once more sodium thiosulphate will decolorize it. This is called the" second fraction" and Majqr Harold indicated it in water by placing aplus sign after the first fraction and then inserted the amount of the 'second fraction; thus 1'0 + 0·5 part per million. In bulk-formed chloramine the second fraction yery seldom occurs and then only in very small amounts.

Efforts were made to ascertain the nature of this second fraction but without success. It disappears, like chlorine, entirely from water after one hour's incubation at 70° C. It persists in water at 15° C. even after the ordinary chloramine (first fraction) has dIsappeared. It responds to tests for small amounts of nitrites (Griess IIosvay) but not in sufficient amount to account for it all. It, gives negative reactions to tests for peroxides, hydrazine, hydroxylamine, hyponitrous acid and nitrogen trichloride.

(4) TIIE PROPERTIES OF CHLORAMINE. '

(a) Sterilizing action: B. coli. The results in Tables Ill, IlIA, IIIB and IIIe show that chloramine will kill B. coli in one part per million river water and in filtered mixtures of sewage and water, both of which contained the naturally occurring organism, also in °tap-water inoculated with organisms from a laboratory culture.

Organisms of Water-borne Diseases.-The results in Tables IV, IVA, IVE, lVe and lVn show that chloramine will kill the organisms of waterborne' diseases in clear water. Laboratory, cultures of resistant'strains were used as they w~re more easily obtainable and more resistant to the action of disinfectants than the naturally occurring organisms.

These results show that chloramine is not so rapid in its action as chlorine, taking with equal doses about twice as long, that a 4 : 1 ratio is more' rapid than a 3: 1 or 2: 1 ratio, and that there' is little difference between preformed and bulk-formed chloramine except in very small doses. As 'shown in Table IIlE chloramine like most other disinfectants is more active as a germicide at blood-heat than at lower temperatures, and as it resiRts a certain degree of heating its' action in the tropics is better than in temperate climates.,

. Other Organisms.-Chloramine will not kill all organisms, for, as shown in Tables VI and VII, Thames water contains an organism very resistant to chloramine. The Pathological Department at the Royal Army Medical Oollege reported that the organism was not pathogenic.

( b) Penetration: The penetrative power of chloramine does not appear to be any greater than that of chlorine and a considerable time is taken to sterilize raw water containing organisms enclosed in pieces of insoluble material.

, Table VI shows this effect on filtered and unfiltered Thames water


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where two parts per million failed to sterilize unfiltered water in two hours but sterilized the filtered water in one hour. One experim~nt showed that it took about three days to sterilize the raw water. As the concentration of chloramine remained unimpaired, this action is obviously due to lack of penetration. '

These results indicate that it is always necessary to filter water ill addition to treatment with chloramine if the water is required quickly.

(c) Taste: To the average person water containing two parts per million of chloramine has 'no taste. Tea containing two parts per million has no unusual flavour. Water containing three parts per million has a slight taste which becomes quite defir:lite when the dose is increased to four parts per million.

Preformed chloramine, made from 1 in 1,000 solutions of sodium hypochlorite and ammonium sulphate and added to water in a strength of one part per million, gives a distinct taste, but preformed chloramine made from weaker solutions is tasteless.

(d) Persistence: In clean water, chloramine persists for days; for example, London tap-water, treated with 2'4 parts of chloramine per million, contained 2'3 parts seven days later.

In contaminated water, chloramine is destroyed to a small extent; for example in filtered water from the RiverStour at Blandford the concentration fell in two hours from 2 parts per million to 1'8. Six hours later, however, the water still contained 1'8 parts per million, a loss of ten per cent. In Table V it will be seen that; chloramine is destroyed to the extent of about ten per cent fairly rapidly and thereafter it loses strength very much more slowly. The suspended matter, it will be noted in this table, does not appear to deviate chloramine to any great extent.

(5) METHODS OF INTRODUCING CHLORAMI,NE ~,NTO WATER SUPPLIES.

(a) The Metropolitan Water Board, the Army authorities at Catterick and other water authorities introduce a small dose of ammonium sulphate solution or of ammonia gas into the water after filtration by means of a Paters on or Wall ace Tiernan apparatus as the water flows through the main, The amount generally used is of the order of one-tenth to one-quarter of a part per million. After a short run through the main, which allows the 9.mmonia to become diffused evenly through the water, chlorine is introduced as gas by means of similar apparatus to the above, usually in the proportion of twice the· amount of ammonia added. As dirt does not destroy chloramine to any serious extent, the substance may be added before filtration and the filters are thus kept more or less sterile, or at any rate organisms will not multiply in them.

It is the usual practice to add the ammonia first as it prevents the destruction of the chlorine by dirt in the water. If the chlorine is added first to contaminated water, a certain amount will be destroyed 'and


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either the. dose will be too Iow for efficient sterilization ,or the dose mUE;t be raised and chlorine will be wasted.

(b) In the Elliott Mobile Water purifier for the purification of water, a wea~ solution of ammonium sulphate is fed at a constant rate into the water as it flows through the intake pipe. The proportion generally used is about half a. part of ammonia per million. A little further along the .intake pipe, chlorine in the. form of a solution of salt which after electrolysis contains sodium hypochlorite, is added usually in the proportion of.about two parts per million but the doses in both cases may_ be varied.

The dose of chloramine in the water is higher than that used for large installations because the water is required almost immediately, whereas in the large installations the water is stored in the reservoirs and mains for some time, thus allowing a sufficient period of contact for the chloramine to sterilize the water. Small doses require a longer period of contact for sterilization than larger doses. .

(c) In the new method proposed by Major F. McKibbin, R.A.M.C., for the Army water-cart, bulk-formed chloramine is used. Two tablets (five grains each) of ammonium chloride are added to the water in the cart when about one-quarter full, and when about half full, two scoopfuls (about sixty grains) of" tropical bleach," previously mixed into an emulsion with water. The movemeQt of the water during the filling process mixes the contents of the cart and distributes the chloramine evenly.

The dose of chloramine amounts to between It and 2 part£ per million, the ammonia being added first.

The official Water Sterilizing Powder may be used instead of tropical bleach (proprietary name Chlorosene) provided allowance is made fo~ any difference in chlorine content.

(d) For the treatment of swimming-bath water with chloramine no data are available except those mentioned in the experiments in reference [8J and the pamphlet" The Purification of the Water of Swimming B.aths," issued by the Ministry of Health, in which reference is made to Race's work. The Plumstead Baths at Woolwich are now using chloramine.

(6) DETAILS OF EXPERIMENTAL WORK.

The objects of the experimental work were to investigate : (i) the chemistry of chloramines and their formatiop, (ii) the bacteriological properties of chloramines, (iii) the chemical and bacteriological properties of chloramine in conta,ct with the dirtiest water available. .

The results of the investigations ar!'l given in the tables printed at the end of this paper :- .

(i). Tables I and lI. The actual practical details of the wor~ are included in each table

for the sake of simplicity. It was foupd that incubation at 600 C. for one hour destroyed free chlorine while chloramine deteriorated to an extent of only 20 per cent. Moreover, it was found that chlorine in as low a


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S. Ellioit 169

concentration as 0'2 to 0'3 part per million bleaches a dilute solution of methyl red in a few minutes, whereas chloramine in large concentrations does not do so. By combining these two facts it became feasible to analyse the substances produced and to find roughly what proportions of free chlorine and of chloramine existed in the mixture. By a further calculation the ratio of chlorine as chloramine to ammonia present could be roughly ascertained and a surmise of the kind of chloramine present, whether mono- or di-, could be deduced. . '

'The lesson to be learnt, from these series of tables is that there appears to be very little difference chemically between "preformed" and "bulkformed" chloramine l11ade according to certain directions given in the tables.

If two of· these directions are not carefully observed the performed variety will be inferior to the bulk-formed type; firstly the concentrations of the solutions to be mixed together before addition to the water must certainly not exceed 100 parts per million, and secondly the mixture should not be preserved for any length of time before addition to the water. Otherwise the dose of chloramine will be below that anticipated.

These tables also show that chloramine made from ratios of chlorine to ammonia higher than 4: 1 contain free chlorine which, of course, is capable of deviation in dirty water.

For the same amount of chlorine,the 4: 1 ratio does not give so large a concentration of chloramine in the water as in the case of the 2 : 1 and 1 : 1 mtios. However, the 2: 1 and 1: 1 ratios are not recommended for Army use as the bacteriological results show that they are slower in their action than the 4: 1 ratio.

Hence to obtain'the most advantageous results, a ratio of four parts by weight of chlorine to one of ammonia is recommended.

(ii) Tables III and IV. In the bacteriological tests, ratios of 4 :1,3: 1 and 2: 1 were used as

higher ratios would include in addition to the chloramine, free chlorine which has been· tested already. ..

The results show that as the proportion of ammonia rises the action becomes slower, that the best ratio for speed and non-deviation is 4 : 1 and that one part of chloramine per million.is sufficient to render a water safe for drinking in from one to one and a half hours. Vibrio cholerce appears to be very susceptible to the action of chloramine, but Bact. pamtyphosunL A and B are not so easily killed. The dose of It to 2 parts per million given in the method for the water-cart proposed by Major McKibbin should render the water safe for drinking in an hour.

(iii) Tables V. VI and VII. With dirty water chloramine is deviated to a small extent, but one part

of chloramine (ratio'4 : 1) will kill in from one to one and a half hours typhoid bacilli in raw water which has been filtered. If the water has not been


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filtered there is a risk that chloramine will not penetrate through particulate matter sufficiently rapidly to kill organisms in the interior, hence filtration or sedimentation in addition to chloramination is recommended.

SUMMARY.

(1) Mixtures of ammonia and chlorine have properties differing from free chlorine, and the compounds produced are commonly known as chloramine.

(2) Chloramine should be prepared for Army purposes by mixing chlorine or its compounds with ammonia or its salts in the proportion by weight of 4: 1. .

(3) The dose of chloramine recommended to sterilize water in one hour for Service purposes is between one and two parts per million.

(4) 80 long as chloramine is prepared correctly and the dose is not allowed to exceed two parts per million, no taste troubles should occur.

(5) Owing to its relatively slow powers of penetration, it is essential that water should be filtered in addition to its ,being treated with chloramine.

In conclusion I wish to thank the Staff of the Hygiene and Pathological Departments of the Royal Army Medical College for their help with this work.

REFERENCES.

[1] RACHIG. Chem. Zeitschr., 1907, xxxi, 926. [2) RIDEAL. Journ. Ray. San. Inst., 1910, xxxi, 33. [3] RACE. Journ. Amer. Waterworks Assoc., 1918, i, 63. [4] Idem. "Chlorination of Water," New York, 1918. [1\] HAROLD and WARD. JOURNAL OF THE ROYAL ARMY MEDICAL CORPS, 1924, xlii, 414.

[5A] HAROLD and WARD. Ibid., 1926, xlvi, 115. [6] ADAMS. Medical Officer, 1~26, xxxv, 55. [7] HAROLD. Journ. Roy. San. Inst., 1928, xlviii, 484. [8] MEDED. Dienst Volksgezindheit in Neder.-India, 1928, xvii, 251, 357. [9] GRIFFITHS.JONES, ATKINsoN and HASSAN. Ann. Trap. Med. and Parasitol., 1930, xxiv, 503.

[10] BERLINER. Journ. Am'11'. Waterworks Assoc., 1931, xxiii, 1320. [11] CHAPIN., Journ. Amer. Chem.·Soc., 1929, li, 2112.

Annnal Reports of the Metropolitan Water Board. The Purification of the Water of Swimming Baths, Ministry of Health, 1929, London. H.M. Stationery Office.

TABLE I.-CHEMICAL RESULTS BULK-IWRMED CHLORAMINE.

A mmonium chloride in the requisite proportion was mixed with one quarter of the water to be sterilized. After addition of a further quarter of the water the requisite amount of "chlorosene" emulsion was added; The remaining half of the water was then mixed in.

Part (355 millilitres) was titrated to check the initial strength, another 50 millilitres were tested with a drop of 1 in 1,000 methyl red in N/10 soda to see if free chlorine was present, and the rest was incubated at 60° C. for one hour. After cooling, 355 millilitres were titrated and 50 millilitres tested for bleaching by free chlorine with methyl red; chloramine did not bleach.


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s. Elliott 171

. PARTS PER MILLION

Ratio Initial Methyl-red Final Methyl-red Loss Los. per cent ClNH3 concentration test concentration test approx,

---- ------- --------- ------------10: 1 1-6 Bleacbed 0'15 iUnbleached 1-45 90 8: 1 1'6

" 0'40

" 1'20 75

6:1 16 Unbl~~cbed

0-65 "

0'95 60 4:1 1-9 1'30

" 0'60 32

2:1 2'2 .. I-50 "

0-70 31 1: 1 2'2

" 2-20

" 0-00 Nil

ANALYSIS OF TABLE 1. The amount of chloramine present in this case is calculated by adding

thirty per cent to the final conc.entration to allow for the loss on heating; the free chlorine concentration is the difference between the initial concentration an<;l. the amount of chloramine found. The ammonia is known from the amount already present and added, and the ratio combined chlorine to ammonia is the ratio of chlorine present as chloramine to ammonia; with a 2 : 1 ratio the product is reckoned as mono-chloramine (NH2Cl) and with 4 : 1 di-chloramine (NHCI2).

PARTS PER MILLION

Ratio Chloramine Chlorine Ammonia . Prodnct

c\NH~ present present present Ratio

------------- ----------------------- -------10: 1 0'20 1'40 0'20 1:1 ? 8: 1 0-50 1-10 0-25 2 : 1 NH2Cl 6: 1 0-80 0-80 0-33 2'40: 1 Mixture 4:1 1-70 0'20 0-50 3-40: 1 Mixture 2:1 1-95 0-25. 1-00 1-95: 1 NH2Cl 1: 1 2'80 - 2'00 1:1 . -

• Combmed cblorme: ammoma by weight,

lA.. Ammonium sulphate was used instead of ammonium chloride, and exactly the same procedure as in the previous table was carried out_

Ratio Initial Methyl-red Final Mothyl-red I Loss Loss per cent ClNH. concentration test concentration test approx_

-----------------.-- ------------------------10: 1 2-00 + 0-005 Bleacbed' 0'20 + 0-(:) Unblea.cbed 1-80 90 8:1 1-85. + 0'15 .. 0'35 + 0'0

" I-50 80

6:1 2-15 + 005 Unbl~~ched

0'65 + 0-0 "

1'50 70 4:1 2-20 + 0'00 1-60 + 0'0

" 0'60 27

2:1 2-25 + 0-00 "

1-80 + 0-0 "

I

0'45 20 1: 1 2-25 + 0-00

" 1'80 + 0'0 "

0'45 20

ANALYSIS OF lA

Ratio Chloramine Chlorine Ammonia [

ClNH. present present present __ --=~ __ I __ prod: __ ----- ---------------- -------

10 1 0'25 1-75 0-20 1-25 1 I ? 8 1 0-40 1-45 0-25 1-60 1 NH2Cl 6 1 0'80 1-35 0'33 3'00 1 Mixture 4 1 1-90 0-30 0-50 3-80 1 Mixture 2 1 2'15 0-10 1-00 2'15 1 NH2Cl 1 1 2'15 0'10 2'00 1-07 1 -


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172 Notes on the Chlorainine Treatment of Water

To compensate for the loss on incubation, twenty per cent was added to the chloramine.

lB. Ammonium sulphate and chlorine water 1 in 1,000 prepared from permanganate and hydrochloric acid and passed through solid hleaching powder. Procedure as before.

Ratio I Init.ial Methyl·red Final Methyl·red Loss Loss p.er cent Cl NH. concentration test con(~entration test approL

----- ----------10: 1 1·80 + 0·30 Bleached Nil Unbleac):J.ed 1·80 100 8:1 1'80+ 0'30

" 0,25 + 0'0

" 1'55 86

6:1 2'05 + 0·15 "

0'70 + 0'0 "

1·35 65 4:1 2'20 + 0·10

.. I 1'65 + 0'0

" 0'55 25

2:1 2'20 + 0'10 Unbl~~Ched 1·85 + 0'0 "

0'35 16 1 : 1 2'30 + 0·05 1.90 + 0'0 ,; 0'40 17

ANALYSIS OF lB.

Ratio Chloramine Chlorine Ammonia Ratio Product present presAnt present

--------------------------- -------10: 1 Nil 1·8 0·20 Nil: 0·2 -8:1 0:30 1·5 0'25 ,1·20: 1 -6:1 0'85 1·2 0'33 2'60: 1 Mixture 4: I' 2'00 0·2 0'50 4·00: 1 NHOl.· 2: 1 . 2'20 Nil 1'00 2·20: 1 NH.Ol 1: 1 2'30 Nil 2'50 1'15: 1 -

Compensation figure twenty per cent.

TABLE II.~CHEMICAL RESULTS PREFORMED CHLORAMINE.

Ammonium 'sulphate 25 parts per million and chlorine gas sol1ttion 25 parts per million mixed in the requisite proportions and stirred into the bulk of the water. The rest of the procedure as before.

Ratio Initial Methyl·red· Final Methyl.red Loss Loss per cen t Cl NH, concentration test concent.ration tP,it approx.

-------- ----------10: 1 1·70 + 0·25 Un bleached Nil Unbleached 1'70 100 8:1 1·70 + 0·25

" 0·15 + 0'0

" 1·55 90

6:1 1·70 + 0'30 " 0·55 + 0·0

" 1·15. 70

4:1 1·85 + 0'20 "

1·45 + 0'0 "

0·40

I

20 2: 1 2·00 + 0·00

" 1·65 + 0·0

" 0'53 16. 1:1 2·10 + 0·00 " 1·80 + 0·0

" 0'30 14

ANALYSIS OF THE ABOVE.

Ratio Chloramine Chlorine Ammonia Ratio Product· Cl NH, prefi€'nt present present

------------ --------------. -------- -------10: 1 Nil 1·70 0·20 Nil 0·2 -8:1 0'18 1·52 0·25 0·72 1 -6 1 0'65 1·05 0·33 1'95 1 NH2Cl 4 1 1·75 0'10 0·50 3'50 1 Mixture 2 1 2'00 Nil 1·00 2·00 1 NH20l 1 1 2'15 Nil 2·00 1·07 1 -


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S. Elliott 173

Loss of chlorine in the mixture on standing for five minutes before addition to the water. A 4 : 1 ratio mixture gave l'S5 + 0'2 parts per million after standing ten to fifteen seconds, but the same mixture after five minutes' standing before addition to the water gave a water containing 1'75 + 0'35 parts per million.

HA, Ammonium sUlphate 100 parts per million and chlorine gas solution 100 parts per million mixed in the requisiteproportions and stirred into the bulk of the water. The rest of the procedure as before.

I

Ratio Initial Methyl,red Final Methyl-red Loss I Loss per cent Cl NH. concentration . test concentration test approx,

------------------- ---------10: 1 1'40 + 0'30 Bleached

I 0'20 + 0'0 Unbleached 1'20 85

8:1 1'55 + 0'30 " 0'40 + 0'0

" 1'15 75

6:1 1'60 + 0'25 I 0-90 + 0'0 0'70 55 " " 4: 1 1-75 + 0'10 Unbleached 1-35 + 0-0

" 0'40 20

2: 1 1'75 +0'10' "

1'45 + 0'0 "

0'30 15 1:1 1'75 + 0'20 .. 1-40+ 0'0

" 0'35 20

ANALYSIS OF HA,

Ratio Chloramine Chlorine Ammonia Ratio Product Cl NH. preseut present present

----- ------- -------- -----10: 1 0'25. 1'15 0'20 1'15: 1 .? 8:1 0'50 1'05 0'25 2'00: 1 NH2Cl 6:1 1'10 0'50 0'33 3'30: 1 Mixture 4:1 1'60 0'15 0'50 3'20: 1 Mixture 2: 1 1'75 Nil 1'00 1'75 : 1 NH2Cl 1:1 1'70 0'05 2'00 0'85: 1 ?

Loss of chlorine caused by delay in treating the water. A 4: 1 ratio mixture gave a water with 1'75 + 0'1 parts per million after a ten seconds' ·delay, but a five minutes'· delay gave a water containing 0'75 + 0'25 part per million.

llB. The same chemicals in a 1,000 parts per million dilution.

Ratio Initial Methyl-reu Fin.l Methyl-red Loss La,s per cent concentration test . concentration test approx,

----- -------------------------------"

10: 1 0'8 + 0'15 Bleached 0'25 + 0'0 Unbleached 0'55 70 8:1 1'0 +0'15 Unbleached 0'60 + 0'0 .. 0'40 40 6: 1 1-0 + 0'15 "

0'70 + 0'0 .. 0'30 30 4:1 1'0 + 0'20 "

0'70 + 0'0 .. 0~36 30 2:1 I'D + 0'20

Ble~~hed 0'80 + 0'0

" 0'20 20

1:1 0'6 + 0'20 0'30 + 0'0 "

0'30 . 50

The last result was anomalous because half a minute elapsed before the mixture was added to the water,


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174 Notes on the Ohloramine Treatment of Wate'l"

ANALYSIS OF lIB.

Ratio . Chloramine I . Chlorine Ammonia I Ratio Product Cl NH. present present present

------------------------10: 1 0'30 0'50 0'20 1'50: 1 8: 1 0'70 0'30 0:25 2'80: 1 Mixture 6:1 0'85 0'15 0'33 2'55 : 1 Mixture 4: 1 0'85 0'15 0'50 1'70.: 1 NH2Cl 2:1 0'95 0'05 1'00 0'95: 1 1: 1 0'35 0'25 2'00

Loss of chlorine caused by delay in treating tbe water. A ten to fifteen seconds' delay before addition of tbe mixture to the water gave 1'0 + 0'2 parts per million, but five minutes' delay gave a concentration 0'1 + 0'25 part per million in the water.

TABLE IlL-BACTERIOLOGICAL RESULTS. B. coli.

London tap-water was inoculated with a normal saline emulsion of B. coli from an agar slope after twenty-four hours' incubation at 37° C~ One millilitre out of a total ten millilitres of emulsion was added to every litre of tap water. For the preformed chloramine, chlorine gas solution 25 parts per million, and for the bulk-formed chlorosene emulsion was used; the source of ammonia was ammonium sulphate. The temperature throughout was ] 50 C. Fifty millilitre portions were inoculated at the requisite intervals into double strengtb MacConkey's medium. The control gave acid and gas (i.e., positive) in one millilitre.

Dose, 1 part per million.

Preformed chloramine Bulk·formed chloramine

4: 1 3 : 1 2:1 4: 1 3: 1 2·: 1

--------------------Concentration at start .. 1'2 + 0'0 1'2 + 0'0 1'1 + 0'0 1'2 + 0'0 1'2 + 0'0 1-2 + 0'0 Methyl-red test .. .. Un- Un- Un. Un- Un- Un-

bleached bleached bleached bleached bleached bleached Ooncentration after 2 hours 1'0't 0'0 1'15+0'0 1'10 +0'0 1'0+0'0 1'20+0'0 1'20+0'0 MacOonkey's medium-

! hour contact Nil A.G. A.G. Nil A.G. A.G. 1

" " " Nil Nil

"

I

Nil Nil I! " " " " " " " " 2

" " " " " " " "

Result: 4 : 1 sterilization in half-an-bour, the remainder sterilization in one hour.

IlIA. As above, but with a dose of ! part per million. Control positive in one millilitre. No" second fractions." .

The preformed variety is more effective than the bulk-formed variety at this concentration.


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oncentration at start C M

.. ethyl-red test ., ..

oncentration after 2 hours C M acOonkey's medium-

! hoo, ,on""" I 1 " " I!" " 2 " "

4: 1

---0'75 Un-

bleached 0'60

A.G. Nil

" "

S. Elliott

Preformed

3: 1 2 :1

--- -----0'75 0'75 Un· Un-

bleached bleached 0'60 0'65

A.G. A.G. A.G.

[

A.G. Nil Nil

" "

]76

Bulk·formed

4:1 3: 1 2 : 1

----- ---------0'70 0'75 0'75 Un- Un- Un-

bleached bleached bleached 0'55 0'60 0'65

A.G. A.G. A.G.

I A.G. A.G. A.G. A.G. A.G. A.G. A.G. A.G. A.G.

. IIIB. As above, but with a dose of t a part per million and the temperature of the water kept at 37° C. (i.e., under tropical conditions). No ,/ second fractions." Control positive in one millilitre.

Preformed Hulk·formed

4 : I 3: 1 2: 1 4:1 3 : 1 2:1

---------------------------- --_._-Concentration at start .. 0'55 0'50 0'55 0'50 0'50 0'50 Methyl-red test .. .. Un· Un· Un· Un· Un· Un·

bleached bleached bleached bleached bleached bleached Concentration after 2 hours 0'35 0'35 0'35 0'30 0'30 0'30 MacConkey's medium-

! hr. contact Nil Nil Nil Nil A.G. A.G. 1 .. " ". " " "

Nil Nil 1~ " " " " " " " .. 2

" " " " .. " " "

At higher temperatures chloramine is much more effective, and at this concentration the preformed variety is more effective than the bulk-formed variety.

IlIe. The source of B. coli in this case was sewage. A sewage effluent was diluted 400 times with London tap-water and treated with one part of chloramine per million and inoculated as above, allowance being made for the small amount of ammonia already present. There was no 11 second fraction," and the control showed B. coli present in one mitlilitre.

Preformed Bulk·formed

4: 1 3 : 1 2 : I 4:1 3: I 2: 1

-------------- --------------- --------Concentration at start .. 0'95 0'95 0'90 1'10 0'95 1'00 Methyl·red test .. .. Un- Un- Un- Un. Un- Un-

bleached bleached bleached bleached bleached hlE>ached Concentration after 2 hours . 0'85 0'90 0'90 0'95 0'90 0'90 MacOonkey's medium-

Nil Acid only A.G. ~ hr. con tact Nil A.G. Nil 1 ., .. "

Nil " "

Nil Nil It " .. " " " " " " 2

" " " " " " " " i


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176 Notes on the Chlo'ramine -Treatment of Water

Naturally occurring B. coli is just as sllsceptible to the action of chloramine as are laboratory cultures.

TABLE IV.-BACTERIOLOGICAL RESULTS. OTHER ORGANISMS. London tap-water sterilized by heat was inoculated at 15° C. with a

saline emulsion of the organisms of resistant strains of bacte~ia from twentyfour hour cultures on agar slopes in quantity to give an estimated number of about 50,000 organisms per millilitre. The water was then treated with chloramine as in Table Ill, -and fifty millilitres were inoculated into fifty millilitres of double strength Rideal Walker broth, controls of the water not treated with chloramine being put up at the same time after the requisite periods of contact. Peptone water instead of broth was used for the cholera. A positive sign in the tables indicates growth in the broth; a negative sign indicates sterility.

Bact. typhosum, Lister strain. One part of chloramine per million.

Preformed Bulk-formed Control Chloramine Chloramine Time of contact

4 : 1 3: 1 2 : 1 4:1 3 : 1 2: 1 Without .chloramine

-------------------Start .. .. .. .. + + + + + + Not subcultured ~ hour .. .. .. - + - - + + + 1 hour .. .. .. - + - - - - + 1~ hours .. .. .. - - - - - - +

I . A 4 : 1 ratio sterilizes in half an hour, other ratios take about an hour. IVA. Bact. paratyphosum A. Mears' strain. One part of chloramine per

million.

Preformed Bulk-formed

Time of contact Control

4:1 3:1 Z: 1 4: 1 3 : 1 2 : 1

------------------ ----- -------Start .. .. .. + + + + + + Not subcultured -! hour .. .. .. - + + - + + + 1 hour .. .. .. - + + - + - + I! hours .. .. .. - - - - - - +

A 4 : 1 ratio kills in half an hour, other ratios take longer.

IVB. Bact. paratyphosum B. Rowland's strain. One part of chloramine per million.

Preformed I Bulk-formed

Time of contact I Control

Star-t ----.. ---~---.-. 4~1_ 3~1 2~1 1~~1 3~1 ~~l NotsUbCUl~;;-! hour .. .. .. - - + + + + + 1 hour .. .. .. - - + - - + + I! hours .. .. .. - - - - - - +


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S. Elliott 177

Preformed chloramine appears to be more effective than the bulk-formed variety j 4 : 1 and 3 : 1 ratios sterilize in one hour.

IV c. Bact. dysenterice Shiga. One part of chloramine per million.



4: 1 3 : 1 2 : 1 4 : 1 .3 : 1 2:1 . ---------------------------Start .. .. .. + + + + + + Not subcultured it hour .. .. .- - + + - - -

I

" 1 hour .. .. .. - - - - - -1~ hours .. .. .. - - - - - - +

IVD. Vibrio cholerce, King Institute No. 5 strain. One part of chloramine per milli9n ..



4:1 3:1 2:1 4:1 3:1 2:1

------------------------------Start ~ hour 1 hour 1~ hours

+ + + + +

+ + Not subcultured + + +

. The 4 : 1 bulk-formed half-hour contact subculture showed only traces of growth and indol. Hence, it may be regarded that 1 part of chloramine per million will kill the cholera vibrio in half to one hour.

TABLE V.-DEVIATION OF CHLORAMINE IN WATER CONTAINING ORGANIC

MATTER.

Comparison of the effect of adding chlorine and preformed and bulkformed chloramine to River Thames water raw and filtered, and to London tap-water. The Thames water already contained 1'5 parts of ammonia per million, and the tap-water was practically free from ammonia. Chlorine, as chlorosene emulsion, was added in equal quantities to each in sufficient quantity to produce theoretically 3 parts per million, and ammonium sulphate was used. In the case of the river water, the proportion was 1 : 1 (3 of chlorine + 1'5 of ammonia already in, + 1'5 of ammonia added, except iu the case of chlorine alone) and in the tap-water 2 : 1, except in the case of chlorine alone. The figures are parts per million.

These tables show that the ammonia already in the water has a slight protective action on the chlorine, yet in the case of dirty wat,er, such as swimming-bath water, it is advisable to use ammonia in addition to that already in the water, and preferably to use bulk-formed chloramine.

12


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Chlorine alone

'I'ap Filtered' I Raw

------'--------------, Initial concentration ., .. 2-60 + 00 2-10 + 0-0 1'95 + 0'0

One hour at 150 C. ., .. 2'60 + 0-0 2-00 + 0'0 1'95 + 0-0

" " 60°C. .. .. 2'15 + 0'0 1'45 + 0'0 1'30 + 00

Preformed chloramine

Tap I Filtered Raw

----------- -----------Initial concentration ., .. 2'85 + 00 2'5 + 0'0 2'5 + 0-0 One hour at 150 C, .. .. 2'90 + 0'0 2-3 + 0'0 2'3 + 0'0

" " 60°C. . , .. 2'85 + 0'0 2'3 + 0 0 2'3 + 0'0

'Bulk· formed chloramine

Tap I Filtered Raw

------------- ------------Initial concentration ., .. 3'10 + 0'0 2-7 + 0'0 2'8 + 0'0 One hour at 150 C. .. .. 3-10 + 0'0 2'6 + 0-0 2'6 + 0'0

" " 600 C, ., .. 3'05 + 0-0 2'5 + 0'0 2'3 + 0'0

TABLE VI.-CHLORAMINE IN THAMES WATER (BACTERIOLOGICAL).

This test showed the difference in sterilizing power of both preformed and bulk-formed chloramine on raw and filtered Thames water containing 0'9 parts NHs per million.

The water was filtered through sand and treated with 3, 2 and 1 parts of chloramine per million, using both preformed and bulk-formed cbloramine prepared from chlorine gas solution and ammonium sulphate in the 4 : 1 ratio.

Fifty millilitres of the water were inoculated into fifty millilitres of double· strength Rideal Walker broth and incubated at 37° C. for two days. A positive sign shows growth, a negative sign sterility.

Pl'eformed chloramine

Raw water Filtered water

Concentration at start 3'0 + 0'7 2'0 + 0'6 0'90 + 0'25 2'9 + 0'7 1'80 + 0'60 0'9 + Q'2

" after two 3'0 + 0'6 1'3 + 0-5 0'85 + 0'15 2'9 + 0'6 1'65+ 0'45 0-8 + 0'1

hours One hour's contact .. + + + - - + Two hours' contact .. + + + - - + .


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S. Elliott 179

Bulk-formed chloramine

Raw water Filtered water

Concentrat.ion at start 3'4 + 0'0 2'20 + 0'0 1'0+0'0 3'3 + 0'0 2'2 + 0'0 1'0 + 0'0

" after two 3'3 + 0'0 2'05 + 0'0 o·g + 0'0 3'2 + 0'0 2'1 + 0'0 o·g + 0'0

hours One hour's contact .. + + + - - + Two hours' contact .. + + + - - +

These tables show that whereas 0 parts of chloramine per million would not sterilize raw Thames water in two hours, the filtered water was sterilized completely by 2 or more parts per million in one hour. The lack or slowness of penetration of the chloramine into the particulate matter appears to account for these results.

TABLE VII.-Bact. typhosum IN FILTERED THAMES WATER.

ChJorosene and ammonium sulphate in various ratios were used, giving a strength of 1 part of chloramine per million oC filtered Tham~s water inoculated with Bact. typhosltm, Lister strain, in normal saline from a twenty-four-hour agar slope. After one and one and a half hours' contact fifty millilitres were inoculated into fifty millilitres of double strength Rideal Walker broth, and in all cases growtli occurred. The contents of each tube were inoculated into mannite (sugar) medium, which was found to be unaffected by the resistant organism in the water but gave with B. coli acid and gas, and with Bact. typhosum acid only after incubation at 370 C.

oncentration at start C

o o

.. .. after two hours ne· hour contact .. .. ne hour and half contact

4: I

1'00 0'85 A.G. Nil

Preformed chloramine

_3~1_~_ 1'0 1'0 1'0 1'0

I A.G. A.G. Nil Acid only

Bulk·formed chloramine

4: I 3 : 1 I 2: 1

-----1'0 1'0 1'0 0'8 O·g Og

A.G. Acid only Gas only Nil Nil N11

These results show that for all practical purposes 1 part of chloramine per million will kill Bact. typhosum in filtered polluted' water in between one and one and a half hours.

[The Director of Hygiene informs us " that the use of chloramine for the purification of water in the field, both in the Regimental Water Cart (McKibbin's method) and in the EllioU Mobile Water Purifier, is at present undergoing practical tests, the results of which will be published in due course." -ED. ] . .


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Documents

our nal - militaryhealth.bmj.comBleachmg powder, water -sterilizing powder, tropical bleach and tI chlorosene" are all easily transportable and, with the exception of bleaching powder,