Sewer rivers : minute of Committee on the practicability of purifying the water flowing from the River Medlock into the Duke of Bridgewater's Canal / Manchester and Salford Sanitary Association.

  • Manchester and Salford Sanitary Association.
Date:
1856
Catalogue details

Licence: Public Domain Mark

Credit: Sewer rivers : minute of Committee on the practicability of purifying the water flowing from the River Medlock into the Duke of Bridgewater's Canal / Manchester and Salford Sanitary Association. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    By Dr. R. Angus Smith and Mr. Mc.Dougall. “ One of our first experiments was to test the greatest rapidity of the current, compatible with complete subsidence of the precipitate in the space allowed us; or in other words, to ascertain the quantity of water which could he clarified in the space, consistent with complete collection of the precipitate. “ We commenced our trials with 125,000 gallons per hour, but found that this quantity did not allow nearly sufficient time for subsidence, the water passing muddy over the dam at the extremity of the basin, taking the precipitate along with it into the Canal. We therefore gradually reduced the quantity to 41,000 gallons per hour, or nearly 1,000,000 gallons per day, which we found to be the maximum quantity allowing of ordinary subsidence in the basin. “ The quantity of lime found to produce instant precipitation without excess or causticity was 17 cwt. for 1,000,000 gallons. The precipitate so made contained no caustic lime; the water ran also free from caustic lime. “We were desired by the Sub-Committee to use our own powder, called ‘ Mc.Dougall’s Disinfecting Powder,’ instead of lime, to compare its efficiency with that of lime; but did not do so, as it would be far too expensive for the treatment of rivers, and could only be used by itself where the liquids were strong solutions. For this reason we used only a small quantity to remove smell and prevent decomposition, leaving the work of precipitation entirely to the lime.” (A.) By Mr. Croce Calvert. Mr. Calvert in his experiments had the help of Mr. Davies, one of his assistants, whose acquirements and professional skill he strongly com- mends. After six experiments, numbered consecutively, and detailed in the appended report, Mr. Calvert arrives at the following conclusions:— “ Experiment vii. By means of ] 0 cwt. of lime, mixed with 6,620 gallons of town’s water:—Gallons of river water purified, 467,606 ; time, 4£ hours. “ Result:—Water so far purified that all the impurity was separated as a flocculent precipitate, but all was not deposited before passing into the Canal. “ Experiment viii. 10 cwt. of lime, 0,270 gallons of town’s water River water purified, 349,034 gallons; time, 4 hours. “ ResultWater clearer than No. vii., hut all impurity not subsided c