GB1292288A - Sewage treatment - Google Patents

Abstract

1292288 Treating sewage SUMNER HOLDINGS Ltd (P C Allam) 28 Oct 1969 52830/69 Heading C1C [Also in Division B1] Raw sewage enters chamber (8), Fig. 4 (not shown), of a settling tank 1. Larger solids in the sewage are retained in chamber (8) and the remaining sewage flows through apertures 17 in screen 16 and into a further chamber 10. A strainer device 18 with a cylindrical apertured screen (37), Fig. 5 (not shown), receives sewage via conduit 20 from the chamber 10 and permits part thereof to return to chamber 10 through conduit 21 and the remainder to pass through a screen (37) and conduit 22 into chamber 12. The interior surface of the screen (37) is scraped by a rotating assembly of spring-loaded blades (42). Sewage is drawn from chamber 12 by a pump 51 and air is injected into it by a device 55 comprising a nozzle 57, a standpipe 58 and a check valve 59. The sewage, which may be heated, is then forced by the pump 51 into an aeration tank 2 containing an assembly of frusto-conical baffles 76, 78, 79, 80, 81. A portion of the aerated sewage is recycled to chamber 12 of the settling tank 1 via manifold 91 and conduit 94. The remainder of the aerated sewage flows into the settling chamber 106 of a combined settling and chlorinating tank 3. Activated sludge is periodically returned from chamber 106 to the aeration tank 2 via conduit 113 and the air injector 55. Clear liquid from chamber 106 flows through a metering valve 116 into chamber 107 and is sprayed with a solution of chlorine or a hypochlorite supplied by a device 119. Treated liquid is periodically discharged from chamber 107 via a duct 120 and a pump. Accumulated sludge in tanks 1, 2 is discharged through pipes (123), (125).