Investigations on the purification of Boston sewage made at the sanitary research laboratory and sewage experiment station of the Massachusetts institute of technology, with a history of the sewage-disposal problem / By C.E.A. Winslow and Earle B. Phelps.
- Charles-Edward Amory Winslow
- Date:
- 1906
Licence: In copyright
Credit: Investigations on the purification of Boston sewage made at the sanitary research laboratory and sewage experiment station of the Massachusetts institute of technology, with a history of the sewage-disposal problem / By C.E.A. Winslow and Earle B. Phelps. Source: Wellcome Collection.
Provider: This material has been provided by London School of Hygiene & Tropical Medicine Library & Archives Service. The original may be consulted at London School of Hygiene & Tropical Medicine Library & Archives Service.
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![Capacity measurements were made on each bed once a week by discharging the effluent into a measuring tank as described above (p. 106). The average results by quarters are brought together m Table LXV. The results are all expressed in percentages of the total cubic capacity of the empty tank. The initial liquid capacity varied from 39 to 48 per cent, the highest values of course being found m the brick and coke beds. The single-contact beds takmg crude sewage all decreased in capacity rather steadily, reachuig a final value after two years of 26 to 33 per cent. The figures do not furnish evidence that the falling off had reached its hmit, as was shown at Manchester. The Dibdm brick filter still showed 40 per cent of open space after one year of operation. The capacity of tank No. 19, which received septic effluent, was maintained at 38 per cent, and the secondary beds, Nos. 17 and IS, retained a capacity of over 35 per cent. The capacity of tank No. 20, which had fallen from 41 to 26 per cent in two years, was measured in August, 1905, after tln-ee months of rest, and had risen to 32 per cent. Table LXV.—Capacity of contact filter, hy quarters. [Percentage of cubic capacity of empty tank.] No. of filter. Inifial. 1903-4. 1904-5. 46 44 41 39 38 38 35 32 40 37 35 33 33 32 31 30 44 37 36 36 35 34 33 48 48 47 '47' 40 16 42 34 30 31 30 17 39 36 34 37 37 37 35 18 42 37 36 38 38 37 37 19 41 40 39 39 38 20 41 39 37 33 32 31 26 It is necessary to distinguish clearly between the surface clogging, due to the accumulation of material on the surface of the bed, and the true loss of capacity which affects the lower part of the filter. Since in these capacity measurements the tank was always filled just to the original surface of the stones, the former phenomenon in no way affects the results. The surface clogging depends directly on the size of material used, being greatest with the fine beds. In the present experiments it was necessary to clean the one-half-inch stone beds once a year, while the 1^-inch beds were just clogging so seriously as to render cleaning necessary at the end of the second year. The surface layer does not extend more than a few inches into the bed, and its removal is a simple matter which could be managed as easily as the scraping of a sand filter. It must, however, be reckoned with in the cost of operation. The true loss of capacity, on the other hand, affected tanks Nos. 11, 12, 13, and 16 about equally, amounting in each case to a reduction of about one-f9urth of the original open space. The ratio of the fmal](https://iiif.wellcomecollection.org/image/b21358205_0141.jp2/full/800%2C/0/default.jpg)
