Engineers and Engineering Volume 26

Engineers and Engineering Volume 26

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1909 edition. Excerpt: a storage reservoir and a regulator for the plant; rise or fall in that basin serves as a guide to decrease or increase the output from the filters, as the case may require. This is done by changing rates of individual filters. The entire 120 preliminary filters at Torresdale have been in service since about March 1, 1909. The time is too short to tell just what the ultimate results of these filters will be. It is expected that they will on an average remove about 70 per cent. of the dirt that caused the short runs on the final filters. We have better control of the filters than before and are never hard pressed to meet the demand on the plant, although it is now delivering double the quantity we were able to filter before the preliminary filters were finished. To replace the preliminary filters would necessitate a sedimentation basin holding over 800 million gallons. The sedimentation obtained by such a basin might be 60 per cent. and it might not. No coagulants of any kind are used at any of the filter plants operated by the Bureau of Water. ' I think it is an advantage to keep the depth of sand uniform. Take a bed with a 40-inch sand layer. By scraping and ejecting it might be reduced to a thickness of 16 inches before it became practicable to re-sand, but by other methods--for example, washing the sand in the bed--the clean sand is returned at once to the bed and the same thickness of sand layer is maintained for all runs. I think that this feature is important, for the efiiciency is not entirely due to the work done by the top layer or "Schmutzdecke," but also to the sand below it. There is an advantage in addition to this: if for any cause the "Schmutzdecke" is broken, it is more probable that a thick bed...
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Product details

  • Paperback | 100 pages
  • 189 x 246 x 5mm | 195g
  • United States
  • English
  • black & white illustrations
  • 1236893670
  • 9781236893673