GB875798A - Improvements in or relating to the treatment of sewage, or industrial waste effluent - Google Patents

Abstract

875,798. Treating sewage &c. ACTIVATED SLUDGE Ltd. July 7, 1958 [July 9, 1957], No. 21651/57. Class 111. [Also in Group VI] In treating sewage or industrial waste effluent by aeration prior to sedimentation, a body of the sewage or effluent is agitated in its lower region by jets of liquid, preferably water, and at the same time is gently aerated, whereby the separation of grease as scum is facilitated. The liquid and the air may be supplied through a common nozzle, one form of which is shown in Fig. 5. This comprises a water-jet 15 connected to a water main 12 and an air-jet 16 connected to an air main by a pipe 17. Another form of nozzle for supplying air and water is shown in Fig, 27, in which a Venturi tube 30 connected to a water main 31 has an air supply pipe 32 attached thereto, the air being drawn in through slots 33. Separate air and water jets may also be used, however, and Fig. 26 shows an arrangement of this kind in which a water jet 25 impinges on a deflector 26 having a central dome 29, air being supplied from a main 27 through lateral openings 28. The sewage or effluent may be treated in a tank in which the jets may direct the liquid longitudinally, transversely or diagonally. As shown, in Fig. 1, the tank 10 has combined air and water jets projecting laterally from a water main 12, air being supplied from a main 13 through a pipe 14. In Fig. 6, the combined jets are arranged on one side of the tank. In Fig. 12 the tank has oppositely directed jets 11 set in a ridge 10a at the base of the tank, and also has partitions 19 to provide an aeration zone 20 and quiescent zones 21. Fig. 15, shows a similar arrangement in which the jets are directed rowards the centre of the tank, and Fig. 21 shows a partitioned tank having separate air jets 22 and water jets 23. In all cases the water for the jets may be derived from the final effluent of the plant. An alternative arrangement is mentioned in which a mixture of air and water is churned into bubbles in a separate tank and the mixture is supplied to jets in the treatment tank. Another gas, e.g. carbon dioxide, may be used instead of air.