Fig. 46.—“Kessel” Tank.
“Separator.”—The second apparatus shown in [Fig. 47] is of an entirely different character, and is aptly designated by the term “Separator.” It consists of a number of comparatively shallow settling tanks, each provided at the top with a metal grating, the separate bars of which are in the form of narrow channels, with open ends discharging into a common effluent carrier. The edges of these channels are accurately planed to form weirs, over which the liquid portion of the sewage flows in an extremely thin film. These channels are provided with adjusting set-screws, so that they may all be set at exactly the same level, and thus ensure a uniform depth of flow over the edges of the whole of the channels in each tank. The combined length of the channels in each tank form a weir of comparatively enormous width, so that the velocity with which the sewage approaches the edges of the channels is extremely low, with the result that a high percentage of the matters in suspension are arrested in the tank and are slowly deposited to form sludge. The bottom of each separate compartment of these tanks is in the form of a sump provided with a sludge valve connected to a common sludge delivery pipe, leading to the sludge disposal area by gravity if the latter is at a lower level or to a sludge well if the tanks are below ground. In order to prevent the decomposition of the sludge from proceeding so far as to cause a nuisance from smell, the deposit in the tanks is drawn off at frequent intervals.
Fig. 47.—“Separator” Tank.
Fig. 48.—The “Fieldhouse” Tank.