GB735790A - Improvements in or relating to small sewage treatment units - Google Patents

Abstract

735,790. Treating sewage; filters. GIBSON, J. July 7, 1953 [March 27, 1953], No. 8604/53. Classes 46 and 111. Hollow inner and outer cylinders are mounted substantially concentrically on a base, a filter medium is contained in the annular space formed between them, and the inner cylinder comprises a sludge digestion chamber and has an outwardly-extending sill forming a drip edge over the filter space, means being provided for leading the raw sewage directly into the sludge digestion chamber. A combined runoff and air-inlet chamber may be provided below the filter medium. Sewage is admitted at 20 into an inner cylinder 12a at the bottom of which sludge settles and from which supernatant liquor flows upwards between the skirt of a scum-hood 15 and the cylinder wall. It flows thence outwards over an annular sill 16 on which the scum-hood is supported by lugs 17 and trickles downward through a filter medium disposed between the cylinder 12a and an outer cylinder 11a and supported on perforate segments 29. Gases produced by digestion in the inner cylinder escape through vents 21 in the scum-hood and pass to the atmosphere at 24. A radial baffle 25 prevents upward entrainment of sludge with those gases. Air gains access to the space below the filter-supporting segments and thence to the filter from a pipe 27 communicating with the effluent discharge pipe 26. Sludge may be withdrawn from the inner cylinder at intervals by a pump the suction pipe of which is passed through an aperture in the lid 22 normally closed by a plug 23. The parts other than the pipes are preferably made of concrete, the cylinders each being in two sections.