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.

    45/356 (page 25)
    Sinijle and Double Contact at the Southern Outfall. The construction of the primary coke-bed for the first stage in the double treatment of sewage was commenced on July the 12th, 1898, but owing to the difficulty of procuring coke at that time, it was not com- pleted until the 1st of September. During the construction of the bed, however, it was frequently charged with crude sewage in order to get forward with the “ maturing ” of the bed. The secondary coke-bed used for the second contact in the double treatment of sewage was also “ matured ” by frequent charges of sewage during its construction. The bed was complete on the 21st of June, 1898, and from that date until the 31st of August, 1898, it was used as a single bed. During that period it received 60 fillings of raw sewage, and 244,200 gallons of sewage in all were passed through it. When the primary coke-bed was completed on the 1st of September, 1898, this bed was worked in conjunction with it as a secondary bed, and it received the effluent from the primary bed and subjected it to a second process of treatment. These beds were filled 219 times between the 1st of September, 1898, and the 22nd of February, 1899. The surface of each working coke-bed was broken up to a depth of several inches twice a week by being raked over ; this kept the surface open, and there was no appearance of its becoming clogged. At longer intervals a hole extending from the surface of the coke-bed to the bottom of the tank was dug in the coke. The whole of the coke on every occasion was found to be perfectly sweet when it was thus exposed, and it possessed only a slight earthy odour. The surface of the upper portion, to a depth of 3 or 4 inches, was not quite bright, but it emitted no foul smell. 1 he results of the chemical estimations of the raw sewage and of the effluents in connection with this series of experiments will be found on pp. 43, 44, 54, 55. 1 he sewage which was subjected to coke-bed treatment varied much in character as judged by the amount of suspended matter and of dissolved oxidisable matter which it contained. The effluent derived from this sewage appeared as a rule to vary in quality with the sewage from which it was produced. It will be understood that the results deal only with the dissolved oxidisable matter in the sewage and in the effluent. The solid suspended matters of the sewage wholly disappeared in the coke-bed, and were therefore not taken into account. It appeal n, however, very probable that the purification of the raw sewage is most complete when the sewage is in a fairly dilute and fresh condition. The least satisfactory results in this series of ex- periments were obtained during the hot dry weather of the summer when the sewage arrived at Crossness in a less dilute condition, owing to the absence ot rain, and in an offensive and putrescent condition owing to the high temperature of the air. Even when the sewage was poured upon the coke-beds in this offensive condition, the effluent from the beds was not offensive in character, and it did not become offensive when it was kept. It differed from better effluents only by containing a larger amount of dissolved oxidisable matter.