The purification of the water of swimming baths.

  • Great Britain. Ministry of Health.
Date:
1929
Catalogue details

Licence: Public Domain Mark

Credit: The purification of the water of swimming baths. Source: Wellcome Collection.

    49/72 (page 39)
    At this stage, 1.e., after 24 hours had elapsed, a similar dose of fresh urine was added. The B. coli in this was sufficient to increase the coli content of the water by 4,800 perc.cm. Counts were made after 4, 6 and 24 hours. ap. B. After 4 hours... % 4,800 11 ron se. ret te No change. 5 Breit +55 es ae Large increase None in 1 c.c. With 0-2 p.p.m. the germicidal action was evidently at an end, but with the larger dose the residual chloramine was capable of dealing with a further increment of pollution. These results, which are confirmatory of those obtained by Dr. Idzerda of the University of Utrecht, whilst working on the same water, but with feecal suspensions as the added pollution, have led to the installa- tion of a chloramine plant for the N.V. Overdekte Bad-en-Zweminrichting *“Het Sportfondsenbad,’’ Amsterdam. This plant, which is the first one manufactured in this country for the purification of swimming pool water by the use of chloramine, has been designed and manufactured by the Paterson Engineering Co., of London. Provision has also been made for the use of a small quantity of sodium carbonate, if the use of an alkali is found to be desirable. In Germany, following the experimental work of W. Olszewski at Dresden (Chemiker-Zeitung, 1927, Nr. 28 and 1928, Nr. 14), chloramine installations have been made in the Guntzbad and the Georg Arnhold- Bad in Dresden and a pool in Halle. Olszewski, in the latter of the two articles cited above, obtains better experimental results with the addition of a small quantity of sodium carbonate. Evidently the object is to neutralise the acid formed by the reaction of ammonia and chlorine NH, + Cl, = NH, Cl + HCl, and which may tend to the destruction of the chloramine. If a water has a sufficiently high alkalinity I should think that the addition of alkali is redundant, but I can well imagine a case in which the low natural alkalinity of a water may be so reduced by repeated coagula- tion with alum as to provide a medium in which chloramine may be unstable. These soft waters, usually derived from upland gathering grounds, are in a class by themselves and often require the addition of an alkali before treating with alum. In experimenting with the chloramine treatment it must be borne in mind that a comparatively strong solution of chloramine cannot be prepared by adding ammonia to either a chlorine solution or to one of a hypochlorite. At laboratory temperatures I found that the maximum stable con- centration was with 120 p.p.m. of chlorine and 30 p.p.m. of ammonia. Higher values merely lead to loss of available germicidal material. The better way is to add the ammonia first at some point in the purification system, before aeration for example, and the chlorine solution later. The ammonia should always be added before, and not after, the chlorine. Chloramine has been in use for 12 years in Ottawa for the city supply, and for about 10 years in Denver, Colorado. In England it has been used for several years by the Metropolitan Water Board—particulars in various reports* by Sir Alexander Houston —and for some months at Belfast. * Especially Twenty-first Annual Report to the Metropolitan Water Board, Sir Alex. Houston, 1927, p. 36, but also Twentieth Annual Report, 1926, -p. 42. °