GB544420A - Improvements in and relating to the separation of grit and like heavier solid matter in the treatment of sewage - Google Patents

Abstract

544,420. Gravityseparating apparatus. HARTLEY, C. J. Oct. 17, 1940, Nos. 15385/40 and 8173/41. [Class 111] [Also in Group II] Apparatus tor separating heavier suspended matter from liquid, for example grit from sewage sludge, comprises an outer tank 11 with a submerged inner container 10, to which the liquid is supplied through a pipe 12 with upwardly-turned end. A'rotary impeller 14, Fig. 1, is provided to cause an upward flow of liquid strong enough to carry away the lighter suspended matter over a weir 23 to an outlet 24. Swirling is prevented by vertical baffles 20, fixed radially either above or below the impeller, and the heavier suspended matter falls through the bottom of the container 10 and is removed from the tank 11 by a bucket elevator 22. Swirling may also be prevented by usmg a second impeller, above and rotating in the opposite direction to the first. Instead of, or in addition to, using an impeller and for the same purpose, the container 10 may be made to contract upwardly to a reduced weir 23, as shown in Fig. 4. A baffle 26 is arranged over the end of the pipe 12 to distribute the liquid entering the container. As shown this baffle is fixed on a rod 30 by which the bell-mouth 13a can also be adjusted vertically. The apparatus shown in Fig. 4 is arranged to receive the deposit from grit channels, through which sewage is passed, the deposit being supplied from a trough 28. The outer end of the pipe 24 may be swivel-mounted or fitted with a vertically-adjustable bell mouth. Air or water jets may be used to assist the separation; for example air-diffuser tiles may be arranged around the bell mouth of the pipe 12.