Abstract: Means and method for controlling submergence of surface aeration apparatus in enclosed covered aeration zones wherein liquid level is dependent on pressure of the overlying gas volume. Power consumption of the surface aeration device is sensed by a transducer coupled in controlling relationship with means for regulating the flow of aeration gas passed through the aeration zone. Changes in power consumption caused by liquid level variation are employed to adjust the flow rate of gas passed through the aeration zone, thereby adjusting the gas pressure in the zone to maintain liquid level therein relatively constant.

Abstract: Apparatus for degassing floating solids containing entrapped gas in an open-topped liquid-solid settling chamber wherein floating solids tend to accumulate at the surface of liquid being separated from solids. Liquid containing floating solids is gently agitated in a trough enclosure for degassing of same to form liquid containing degassed solids, and the latter is discharged from the trough disclosure into the liquid-solid settling chamber.