Fig. 104.-Travelling Distributor.
Messrs. Ham, Baker and Co., Ltd., have for some time supplied an automatic travelling distributor. This is illustrated in [Fig. 104], from which it will be seen that it consists of a water-wheel mounted on rollers and divided into sections composed of a number of buckets. The sewage is delivered through a syphon and patent reversing valve, in such a way that alternate sections only of the filter bed receive sewage in each direction of travel, thereby insuring equal inter-delivery periods.
Fig. 105.—“Hanley” Power-driven Travelling Distributor.
Power Driven Travelling Distributors.—The well-known Hanley Distributor was specially designed by Messrs. Wilcox and Raikes, Civil Engineers, for use on their schemes at Hanley, Fenton, Ilkeston and elsewhere, as illustrated, [Fig. 105]. The object of this distributor is to ensure intermittent discharge at regular intervals, and at a predetermined rate, in the form of a thin film over the surface of fine grade material, and in order to secure these results it was decided to drive the distributor by electric power rather than depend upon the variable and limited amount of power obtainable from the head of the sewage itself. The distributor consists of a pipe extending across the whole width of the bed and supported on wheels, so that it may be drawn backwards and forwards by means of the wire rope attached to the centre. The distributing pipe tapers towards the end farthest from the supply trough, and the sewage is discharged by means of nozzle pipes attached to the flat side of the distributor about 3 inches apart, and connected with it near the top so that the main pipe always remains full. The discharge of the sewage commences and stops along the whole length of the pipe almost simultaneously, and any sediment lies in the bottom of the main pipe where it cannot obstruct the outlets of the nozzles. The nozzles are about ⅝ inches in diameter, and provision is made for cleaning them by removing a plug in the top of each. In order to secure a uniform interval of time between each dose of sewage discharged on to any part of the filter, the distributors are arranged to discharge when travelling in one direction only, the valves on the outlets of the feed syphons being automatically turned off and on by means of a lever, which is actuated by stops fixed at each end of the iron trough or at any intermediate point desired. In this way it is possible to arrange for any portion of the filter to be thrown out of action when necessary for cleaning or repairs. The speed at which the distributor travels may be varied by adjusting the gear wheels attached to the electric motor. At Hanley it has been found that the best results are obtained when the distributors occupy about 7 minutes in making one complete journey, the filters being 200 feet long, so that when the filters are working at the normal rate of 1,000,000 gallons per acre per day, each dose represents one gallon per square yard. In other words, the film one-fifth of an inch in thickness is applied 200 times per day, and thus a total depth of 40 inches of sewage is distributed over every portion of the filters in operation in 24 hours. The power required to drive the distributors is about 1½ B.H.P. per acre of filter. Electric motors are usually adopted, but small oil or gas engines may be substituted when electric current is not available. The winding drums for the wire ropes are driven by belt gear of the usual type with fast and loose pulleys. The reversal of the drum when the distributor reaches either end of the filter is accomplished by an automatic belt striking gear, and a float in the supply trough is used to cut out a distributor, or continue in action at a reduced rate, when the supply of sewage becomes insufficient to maintain the normal rate of distribution. These distributors are manufactured by Messrs. Blakeborough and Sons, and have now been in regular use since 1902 on the Hanley Sewage Disposal Works, where the remarkably satisfactory results obtained are largely due to the highly efficient system of distribution on the filters.
