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.

  • Winslow, C.-E. A. (Charles-Edward Amory), 1877-1957.
Date:
1906
Catalogue details

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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    has been fully discussed elsewhere (Winslow, 1905 a). The analytical characters of the effluent from tank No. 1 are given in Table LXIII. The free ammonia once reached 9 parts per niillion in the summer quarter of 1904, just after the increase in rate, but has been generally under 4 parts. The albuminoid nitrogen has been under 1 part, and the oxygen consumed under 8 parts except in one quarter. The ni- trates, on the other hand, have not fallen below 20 parts, indicating a very liigh degree of purification, and dissolved oxygen has con- stantly been present. The increase in rate from 0.1 to 0.2, and again from 0.2 to 0.4, did not appreciably alter the quality of the effluent. The surface of the fflter, even at these high rates, has not required excessive care. It was scraped in August, 1903, and November, 1904, and raked once and scraped once in March, 1905. The total material removed in three scrapings during two years of operation amounted to a layer 0.48 inch thick, or 1,600 cubic inches. This is equivalent to 0.36 cubic yard per million gallons of sewage filtered. Tanks Nos. 24 and 25 were put in operation in March, 1904, in order to compare the treatment of septic effluent with the purification of crude sewage as conducted in tank No. 1. All tliree were alike in con- struction. Tanks Nos. 24 and 25 were thi-oughout operated at a rate of 0.4 million gallons per acre per day, taking four daily doses at six-hour intervals. Tank No. 24 received the effluent from tank No. 7, which had been septicized for twelve hours; tank No. 25 that from tank No. 9, which had been septicized for twenty-four hours. The analyses of the effluents from tanks Nos. 24 and 25 are shown in Table LXIII. In each of the three tanks studied the nitrates increased rapidly dur- ing the first months of operation (nine months in the case of tank No. 25, six months in the other two cases) and then fell to a somewhat lower value. Fig. 17 brings out more clearly the relative quahty of the thi-ee effluents, showing that from tank No. 1, wliich took crude sewage, to be the best. In the figure the blocks for sewage constituents represent not the septic effluent applied, but the crude sewage before treatment. It will be noticed that the average sewage applied to tank No.l was stronger than that treated by septic tanks Nos. 7 and 9 and fflters Nos. 24 and 25. Nevertheless, the free and albuminoid ammonia values are lower and the nitrates higher after sand filtration alone than after combined septic and sand treatment. In the condition of the surface, the filters receiving septic effluent showed a slight but distinct advantage. During fifteen months of operation tank No. 25 was raked over twice, in September, 1904, and March, 1905, but not scraped. Tank No. 24 was raked on the same dates and also scraped once in March, 1905. This scrapmg was ren- dered necessary by a rather unusual phenomenon, the deposition ot a thin layer of finely divided sulphide of iron formed by decomposition