GB576329A - Improvements in aeration of percolating filters - Google Patents

Abstract

576,329. Percolating filters for sewage and other foul liquors. HARTLEY, C. J. Oct. 2, 1943, Nos. 16191 and 21512. [Class 46] A percolating filter for sewage or other foul liquors or trade wastes is aerated by a fan or other means blowing air into, or exhausting air from, a covered channel centrally arranged in the bottom of the filter and communicating with the under-drains of the filter which channel serves also as the effluent discharge channel, being provided at the discharge end with a liquid-trap air seal. Alternatively the aerating air may be supplied to a peripheral pipe communicating with the outer ends of the under-drains, the effluent discharge channel being as above. As shown in sectional elevation. Fig. 1, and plan, Fig. 2, sewage is distributed by a rotating arm 27 over bricks 32 laid honeycomb fashion in a circular tank 20 to provide filtering clearances and the filtered liquid drains away through under-drains 29 formed by half-round tiles to a covered diametral channel or well 28, closed at one end and having a liquid-trap air seal 34, Fig. 3, at the other end. The usual rotary distributing arm 27 is supported on a hollow central pedestal 21 which is formed over and in communication with the covered channel 28 and into which air is blown by a fan 30 to pass to the under-drains 29 and so upwards through the liquid being filtered. The ducts are shown extending at right angles from the diametral channel 28 but may be arranged radially or in herring bone manner The liquid seal is of such height that it is not broken by the air pressure and the filtered liquid passes away by the effluent pipe 38. The top of the filtering tank may be enclosed by a roof, heating arrangements provided,-and the air may be re-circulated with any necessary air admitted by a valve to make up for the exhaustion of the oxygen. The. percolating tanks may be subdivided with valve arrangements to control the air supply to the separate sections. The arrangement may be applied to a rectangular bed with oppositely-moving connected distributors travelling on rails, Figs. 4-6 (not shown).