The experimental bacterial treatment of London sewage : being an account of the experiments carried out by the London County Council between the years 1892 and 1903 / by Frank Clowes and A.C. Houston.

  • London County Council
Date:
1904]
Catalogue details

Licence: In copyright

Credit: The experimental bacterial treatment of London sewage : being an account of the experiments carried out by the London County Council between the years 1892 and 1903 / by Frank Clowes and A.C. Houston. Source: Wellcome Collection.

    48/356 (page 28)
    and fillings varied according to the number of times it was filled during the 24 hours. When the number of fillings per day did not exceed two, the fillings were made during the daytime, but when the number of fillings exceeded two, they were distributed evenly over the whole 24 hours. The bed was charged once only on Saturdays and remained empty on Sundays and on holidays. The other rests were due either to accidents occurring to the driving belt or to the pump, or to the necessity arising for making alterations in the arrangements or for making capacity determinations of the bed. Taking the average sewage capacity of the bed as being equal to 6,000 gallons, the quantity of sewage dealt with per acre per day would be, for one filling, 1,089,000 gallons ; for two fillings, 2,178,000 gallons: and for three fillings, 3,267,000 gallons. In the table on pp. 54 and 55 are set forth the averages of the chemical examination of the crude sewage as supplied to the bed and of the effluent from the bed for each of the periods mentioned above. Throughout the period during which the coke-bed was filled four times a day, the effluent from it was clear and free from odour. In order to ascertain whether the surface of the fragments of coke became fully aerated throughout the bed between the successive chargings with raw sewage, two vertical pipes were inserted into the bed reaching to the depths of 6 feet and 13 feet respectively. After the sewage had flowed away from the bed, samples of air were drawn oft' from the interspaces between the coke fragments at stated intervals, and the percentage proportions of oxygen and carbonic acid were estimated in this air. The results, which in the case of the 13-foot, depth were only of a preliminary character, indicated that even after the air had been in contact with the lower strata of the coke for 70 hours, the air still contained an average of about 75 per cent, of its original oxygen, and the average amount of carbonic acid did not exceed 3 per cent., as is indicated by the tabulated results below. This evidently represents an entirely satisfactory condition of aeration of the coke surfaces. A more detailed statement of the I’esults of analysis of the interstitial air is given in the following table :— Table VII. Six-foot depth. Thirteen-foot depth. Number of hours since sewage drained off. ] Percentage of oxygen in the air from the bed. Percentage of carbonic acid in tho air from the bed. Number ot hours since sewage drained off. Percentage of oxygen in the air from the bed. Percentage of carbonic add in the air from the bed. 4 10-8 0'4 22 18-4 1'4 21 <>•8 6-8 26'7) 140 3'8 24-5 too fi-0 50'75 14-8 3'0 37 17-8 2 0 51-25 16 3 3'3 4 O'.') 16-8 2-4 70 14 7 0-8 The results prove that, even in the case ot the deep 13-foot bed, the air at the lower part of the bed was not seriously deficient in oxygen.