Combined oxygenation and settling tank

摘要

Sewage to be treated is fed to aeration tank 1 by inlet 59 where it is oxygenated by a surface aerator of the type described in Specification 1,085,760. Flow takes place as indicated by arrows F1 to F5 with clarified liquid leaving by outlet 62. A fluidized bed of activated sludge is maintained in settling chambers 63 and 51 with a withdrawal of excess sludge taking place through outlet 64. The base of aeration tank 1 may be altered (Figs. 1A, 1B, 5 & 6, not shown) or replaced with vanes (Fig. 1C, not shown). Lime may be added to the surplus sludge before drying. A compensating tank which allows for excess feed to a system is described in relation to Figs. 2 an 4 (not shown).