GB1406255A - Process and apparatus for treating wastes by - Google Patents

Abstract

1406255 Sewage treatment J TYMOSZCZUK 10 Aug 1972 37276/72 Heading C1C A sewage or waste liquids treatment comprises maintaining a biological filter bed zone containing a finely divided filtering media; maintaining an activated sludge zone in upstream fluid flow relationship to the filter bed zone; feeding sewage or waste liquids to the sludge zone and after treatment therein to the biological filter bed zone; during the passage of the sewage or waste liquids therethrough aerating both the zones; withdrawing treated effluent from the biological filter bed zone; maintaining the biological filter bed submerged during the passage of the sewage or waste liquids therethrough and backwashing this zone. The biological filter bed may be in multiple layer form (Fig. 2), or may comprise several layers of biological filter beds, said layers being optionally physically separated (Fig. 3, not shown). A non- aerated filter bed may be placed beneath an aerated bed (Fig. 4, not shown). The whole filter medium (Fig. 7, not shown) or only the upper layer thereof may be recirculated (Fig. 6), e.g. by employing an air lift. Backwashing may be achieved by using an increased volume of aeration air or by using an air/aqueous liquid, e.g. water or purified waste. In a modification of the above treatment, sewage or waste liquids flow upwards and is fed to the biological filter bed zone in an upstream sewage or waste liquids flow relationship to the activated sludge zone.