Annual report of the Director of Public Health for the Government of Bombay.

  • Bombay (India : State). Public Health Department.
Date:
[1923]
Catalogue details

Licence: Public Domain Mark

Credit: Annual report of the Director of Public Health for the Government of Bombay. Source: Wellcome Collection.

    59/184 (page 49)
    Ninety-nine water samples were received from several municipalities, prisons, distillery, tanks, etc., and 149 were examined for experimental purposes. The total for the year was 2,711 samples examined bacte- riologically and 3,044 chemically. The following change in the routine at the Cantonment Water-Works was introduced from 22nd July to 7th October, the period when the Canal water is heavily charged with red silt held in emulsion by colloidal clay. Alum was added to the raw water at its entry into the settling tanks instead of at the point when it leaves them to enter the filters. This procedure was found to effect a fair degree of sedimentation in the tanks, in addition to leaving sufficient alum flock for filtering purposes by the time the water entered the filters. The practice relieves most of the extra load on the filters and is, therefore, an economy. A special alum tank has, therefore, now been constructed for use in future monsoons. Filters numbers 4, 3 and 5 were found to have deteriorated. Cracks in the upper layer of fine sand were frequent. The fine sand was found to have sunk to some extent into the deeper layers as a result of the seven years of working. These filters were emptied and the materials cleaned, re-graded and re-laid. Laboratory examination of filtrate carried on when they were again put into commission showed that 16, 21 and 25 days respectively were required before they reached full efficiency. The year’s average bacterial count for the raw water was 445 total colonies (on nutrient agar) and 150*5 colonies of the typhoid group (on bile-salt agar) per cubic centimetre and for the finally chlorinated water 6*45 and 0*01 per c .c. This, as Dr.Mama states in his report “ amounts to a 98*5 percent purification. The graph maintained throughout the year for the finally treated water lies flat and close to the base line. ” In addition to such routine work as mentioned above the following experimental work was done at the laboratory:— (а) Determination of the percentage of purification effected per se by the addition of alum in the old settling tanks during the monsoon. It is to be added that settlement per se in the tanks (2| days capacity) was shown by Dr. Pinto to effect 74*5 per cent, of purification in the ordinary season. (б) Comparison of rapidity and efficiency of sterilization by bleach¬ ing powder and potass permanganate for drinking waters generally. Information on special subjects of water supplies and details on labo¬ ratory technique were supplied to (1) H. E. H. The Nizam’s Superintend¬ ing Engineer, Hyderabad, (2) the Chief Medical Officer, Sangli State, (3) the Director of Bengal Public Health Laboratory and (4) the Health Officer, Public Health Laboratory, Delhi. * The Officer in charge paid special visits to Ahmednagar and Alandi, to advise on technical matters in connection with water supplies there. Karachi Public Health Laboratory.—Dr. Fred Barretto, D. P. H., was in charge Public Health Laboratory, Karachi. p 1—7