pipe distributors. The working parts of this distributor are shown in Fig. 30, while the principle is made evident by the FIG. 30.-SECTIONS THROUGH MATHER AND PLATT'S REVOLVING TROUGH DISTRIBUTOR, SHOWING TURBINE WHICH MOVES IT. sections through the turbine there given. An illustration of the apparatus at work is given in Fig. 31. The sewage rises up the central shaft, passes through the turbine, and falls over a lip into a collecting channel. This lip is a recent improvement, and prevents any leakage at the centre of the filter. The sewage, after it has passed through the turbine, falls into a circular collecting channel around the periphery of the turbine from which the distributing trough is fed. The Scott-Moncrieff Distributor. With all revolving distributors there is a real difficulty, more especially with revolving pipes, in distributing the sewage so that each superficial yard of filter receives the same amount of sewage, and although the holes in the pipe may be apportioned so that theoretically this is done, as the pipe revolves at varying rates, centrifugal action is greater at the greater velocity, and an increased amount of sewage is distributed over the periphery of the filter. With distributors tested by the author, he has found the variation to exceed 60 per cent. Mr. Scott-Moncrieff has introduced a revolving trough distributor which is quite free from this objection, as it always revolves at the same rate, and the amount of sewage falling at different distances from the centre of the filter is regulated by raising or lowering a series of overflow weirs. This distributor is only suitable for large beds. There is already one at Birmingham, and another at Hanley. Fig. 32 gives a view of the distributor at work at Birmingham. The sewage rises up the central feed tank and overflows along the trough, which is kept rigid, like a girder-bridge. Around the circumference of the filter is a tram-line, along which a small oil-engine slowly revolves, turning the trough. The author would like to see a trough tried constructed on the cantilever principle across the whole diameter of the filter, and turned by a motor running on rails on the ground level instead of an elevated tram-rail above the filter. The Latest Revolving Distributor.-Mr. Lomax has, at Belper, adopted the Howard distributor, which is turned by the effluent flowing round a channel around the base of the filter.* Messrs. Mather and Platt have introduced a revolving trough actuated by an electric motor at the centre. When there is insufficient fall to turn a revolving arm, obviously *The corporation of Chesterfield and Messrs. Evans, of Darley Abbey, have recently constructed revolving arms of simple design, which act well. |