GB975041A - An improved apparatus for treatment of sewage - Google Patents

Abstract

975,041. Centrifugal separators. GOODENOUGH PUMPS Ltd., P. J. THACKRAY, and D. E. LAWRANCE. Nov. 6,1963 [Nov. 8, 1962], No. 42287/62. Heading B2P. A centrifuge for separating the liquid and solid components of sewage comprises a rotary bowl 11 having around its upper edge a perforated lip 10 extending substantially radially inwardly of the bowl, the latter being rotated, e.g. through belt and pulley 24, 23, by means of an electric motor 25 so that, as the sewage is fed to the bowl by an inlet pipe 29, the solid components are separated by centrifugal force and accumulate below the lip on to .the wall of the bowl as a removable compact annular cake, while the liquid components are caused to flow axially of the bowl and over the weir formed by the lip, a proportion of the liquid flowing through the perforations in the lip in order to prevent, or reduce the amount of, liquid accumulating in the cake and remaining in the bowl after centrifugation. The bowl is provided with a removable lining 16 in the form of a hessian bag which is held at its upper edge by pins 8 and clips 9 and is clamped at its centre to the boss of a conical retaining member 7 held in position by a wing nut 6 on to a central conical boss 12 in the bottom of the bowl. Vanes 5 are attached to the member 7 for agitating the sewage as it is fed into the bowl. The bowl is surrounded by a housing 26 closed by a hinged lid 28 and provided with a side outlet 34. The housing is resiliently suspended from pedestals 37 by spring-loaded rods 36. A tubular perforated ring 31 supplies compressed air into the housing. A brake band 38 is mounted on the bowl spindle 17 and may be stretched to stop the bowl by a roller 41 rotated by a lever 42 connected by an arm 43 to a shaft 44 to which a handle 45 is secured. Linkage may be provided to prevent the lid 28 being opened while the brake is off. In operation, the liquid is thrown into the space between the housing and the bowl as a fine spray which is aerated by the air from ring 31 and the liquid is discharged through outlet 34 to a contact tank in which the liquid is purified by contact with the air and may then be passed in the centrifuge a second time to remove solid material produced as a result of aeration. When the accumulated solid mass has nearly reached the edge of the weir, the centrifuge is stopped, the lip 10 removed and the lining with the solids is removed and a new lining fitted. The centrifuge may be used in conjunction with a balance tank for intermittent operation.