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41
Table XII.— Average percentage purification effected by the Chemical Treatment and subsequent Sedimentation
of the Sewage, by the Settling Tanks used in connection with Coke-beds and by the various Coke-beds at
the Outfall Works.
The purification is calculated from the relative quantities of oxygen absorbed from permanganate by the liquid,
both before and after treatment. The two sets of figures represent the percentage removal of total putrescible matter
(the crude liquid) and of dissolved putrescible matter (the clear liquid). Except in the case of the figures representing
the purification effected by the chemical treatment and subsequent sedimentation, each set of figures represents the actual
purification effected only by the individual tank or bed. Any purification effected on the liquid previous to or subsequent
to that effected by the tank or bed in question has not been considered in the calculations.
One or less number
of fillings of the
bed per day.
Two fillings of the
bed per day.
Three fillings of
the bed per day.
Four fillings of the
bed per day.
During the whole
experiment.
By the
crude
liquid.
By the
clear
liquid.
By the
crude
liquid.
By the
clear
liquid.
By the
crude
liquid.
By the
clear
liquid.
By the
crude
liquid.
By the
clear
liquid.
By the
crude
liquid.
By the
clear
liquid.
Northern Outfall.
The one-acre coke-bed ("chemical" effluent), ... ... 85.6 84.0 ... ... ... ... 85.6 84.0
1900 and 1901
Series I.—
Primary coarse ragstone-bed (crude sewage) ... 20.2 ... 21.0 ... ... ... ... ... 20.6
Primary coarse coke-bed (crude sewage) ... 22.3 ... 22.6 ... ... ... ... ... 22.5
Secondary fine ragstone-bed (second contact) ... 33.3 ... 38.7 ... ... ... ... ... 35.9
Secondary fine coke-bed (second contact) ... 54.7 ... 50.2 ... ... ... ... ... 52.6
Series II.—
Primary coarse coke-bed A (crude sewage) 53.3 43.7 52.5 48.9 ... ... ... ... 52.7 46.3
Primary coarse coke-bed B (crude sewage) 52.5 43.8 55.2 50.2 ... ... ... ... 54.8 47.0
Secondary coarse coke-bed A (second contact) 33.3 33.9 36.9 30.0 ... ... ... ... 36.0 31.9
Secondary fine coke-bed B (second contact) 66.8 60.1 58.4 44.1 ... ... ... ... 60.8 52.1
Series III.—
Single coarse coke-bed A (settled sewage) ... ... ... ... ... ... ... ... 39.4 38.8
Single fine coke-bed B (settled sewage) ... ... ... ... ... ... ... ... 59.0 51.2
Chemical treatment and sedimentation 1900 ... ... ... ... ... ... ... 32.8 Nil
Chemical treatment and sedimentation 1901 ... ... ... ... ... ... ... 25.8 Nil
Southern Outfall.
Series I.—
4-foot single coke-bed (crude sewage) ... ... ... ... ... ... ... ... ... 52.8
6-foot primary coke-bed (crude sewage) ... ... ... ... ... ... ... ... ... 49.9
6-foot secondary coke-bed (second contact) ... ... ... ... ... ... ... ... ... 38.6
Series II.—
13-foot single coke-bed (crude sewage) ... 53.3 ... 47.2 ... ... ... ... ... 48.1
13-foot single coke-bed (roughly settled ... ... 62.9 57.8 52.6 52.2 ... ... 57.2 54.6
sewage)
13-foot single coke-bed (settled sewage) ... ... ... ... ... ... 56.6 55.7 56.6 55.7
4-foot single coke-bed (continuous flow of ... ... ... ... ... ... ... ... 40.8 48.9
settled sewage)
Settling channels (Dec. 21st 1899 to Jan. 13th ... ... ... ... ... ... ... ... 16.1 00.4
1900)
Small tank coke-bed (settled sewage) ... ... ... ... ... ... ... ... ... 52.9
Series III.—
Settling tank (crude sewage) ... ... ... ... ... ... ... ... 12.0 Nil
3-foot single coke-bed No. 1 (settled sewage) ... ... ... ... ... ... 49.7 49.4 53.5 50.9
3-foot single coke-bed No. 2 (settled sewage) ... ... ... ... ... ... 47.2 46.8 53.0 50.9
Chemical treatment and sedimentation, 1900 ... ... ... ... ... ... ... ... 25.9 11.7
Chemical treatment and sedimentation, 1901 ... ... ... ... ... ... ... ... 29.6 12.2
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