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.

    23/356 (page 3)
    II. Preliminary Experiments at the Northern Outfall Works (Barking). On the 10th of March, 1891, the Main Drainage Committee of the London County Council ordered that a series of experiments should be made at the Northern Outfall Works to ascertain the value of the treatment of sewage effluent in bacteria-beds, or “filters,” as they were then called. The sewage effluent which was treated in these beds and in the one- acre coke-bed, described in section III., pp. 5 to 9, unless otherwise stated, was the effluent obtained by subjecting the sewage on the north side of the Thames to the usual treatment. This treatment consists in the addition of about 4 grains of lime as milk of lime and of about 1 grain of sulphate of iron in solution to each gallon of raw sewage; this is followed by sedimentation in brick channels approximately 1,000 feet in length. The chemicals are added to the raw sewage at some distance from the penstocks of the settling channels, in order that an opportunity may be afforded of their becoming thoroughly mixed with the sewage before it undergoes sedimentation. On arriving at the channels the sewage is allowed to flow continuously through them at the rate of about 6 feet per minute, and at the further end the effluent flows over a weir wall into a common effluent-culvert and thence into the river. A unit of sewage occupies about 2f hours in traversing the length of the channel during sedimentation. For the purpose of carrying out these experiments, four wooden tanks were constructed, each of which was equal in area to ^Jothpart °f an acre. The beds in these tanks were composed of the following materials. “Filter” No. 1 was composed of burnt ballast. This material was obtained by burning clay which had been taken from the marsh land adjoining the Outfall Works. The tank was filled with the burnt ballast to a depth of 4 feet, the larger pieces being placed at the bottom, and the remaining unsifted portion being placed on the top. “ Filter” No. 2 was composed of pea ballast. The material was Lowestoft shingle of pea size, and the tank was filled with it to a depth of 4 feet. “Filter” No. 3 was composed of coke-breeze. The tank was filled with the coke-breeze to a depth of 4 feet, and 3 inches of gravel were placed on the top to prevent the coke from floating. “ Filter ” No. 4a was composed of gravel and sand. One of the tanks was divided into two portions by a wooden partition. One of the portions, occupying two-thirds of the area of the entire tank, was used for No. 4a “ filter,” and was filled with a bottom layer, 5 inches in depth, of walnut-size gravel and successive layers of 2£ inches of bean-size gravel, 1^ inches of pea-size gravel and on the top 10 inches of sand. “ Filter” No. 4b. The remaining portion of the tank, which occupied one-third of the area of the entire tank, contained “ filter” No. 4b, which was composed of a bottom layer of 3 inches of walnut- size gravel and successive layers of 2 inches of bean-size gravel, H inches of pea-size gravel, 1 inch of sand and 12 inches of