Plant for sewage treatment by oxidn. and settlement - recycles settled sludge and surface scum to raise efficiency and increase capacity

摘要

The parent patent describes a packaged plant for the treatment of sewage by oxidn/agitation followed by decantation; basically, a horizontal, cylindrical vessel is divided by a partition into two, axially-alongside tanks, the first receiving sewage which is agitated and aerated by the ibjection of compressed air and te second for settlement treatment of effluent transferred from the first tank, the partition being inclined to the axis of the vessel so that the settlement tank is axially longer at the top than at the bottom. In the addn., the end wall of the settlement tank, opposite to the partition meets the partition at the bottom of the tank and slopes, symmetrically upwards and away from the partition w.r.t. a vertical plane through the tank bottom apex. Pref. the settlement tank is fitted with a partly-immersed chimney from which surface scum is piped back into the oxidn. tank. Pref. also, sludge collecting at the bottom of the settlement tank is sucked back into the oxidn. tank via a sparge pipe extending over about 120 degrees of the apex joint. The changes increase the capacity of a given size of plant.