Fig. 106.—“Stoddart” Distributor.
Fig. 107.—“Stoddart” Distributor.
Fixed Distributors. Trays and Troughs.—One of the best known of the fixed distributors is the “Stoddart,” as illustrated in [Figs. 106] and [107]. It will be seen that it consists of trays of galvanized sheet iron, formed into a number of V-shaped troughs. The ridges between the troughs are provided with diamond-shaped perforations at frequent intervals, and in the bottom of the troughs drip points are inserted through holes to project on the under side. The distributing trays are bolted to specially designed supply channels, connected to a common channel, and the whole of the troughs are mounted on adjustable chairs ([F, Fig. 106]) carried on tees, which are in turn supported on concrete or brick piers. As the liquid passes into the V-shaped troughs, it fills them and overflows through the diamond-shaped slots in the ridges and thence trickles down on the under side of each trough and drops off from the drip points on the filter below in the form of rain. It is claimed for this method of distribution that the whole of the available fall is utilised; that it adapts itself without adjustment to all rates of flow, however varied, that the sewage and storm-water may all be treated on the same area, and that there is a total absence of moving parts. This distributor is supplied by the patentee, Mr. F. W. Stoddart, of the Western Counties Laboratories, Bristol.
Another type of fixed distributor is fixed only so far as actual distributing channels are concerned. This is manufactured by Messrs. W. E. Farrer, Ltd., and illustrated in [Fig. 108]. The fixed troughs or channels are laid directly over the filter-bed, and fitted at the inlet end with concentrating chutes which receive the discharges from a double-acting tipping trough, which is supported at its extreme ends by heavy gun-metal bearings. If it is over 10 feet in length, an additional support is provided at the centre in the form of a specially designed rocker. The chutes and the channels are provided at the bottom with ¼-inch holes at 3-inch centres, through which the sewage is spread on to the surface of the filter, which is below the underside of the trough. The channels are arranged at 1-foot centres, so as to distribute the sewage over the whole area of the bed. By means of the double-acting tipper each half of the filter is dosed alternately, and suitable periods of aeration are thus provided. This apparatus is suitable for a single small house with 4 or 5 inmates, and for larger filters of 600 square feet in area and upwards.
The Ducat filter is provided with what may be termed a fixed distributor. It consists of a series of small tipping troughs fixed across the filter, each of which when full tips its contents on to the filter below. The liquid is thus discharged at the same point each time, but intermittently in small doses. As, however, the distributor does not move it is included under this heading.
