Abstract: A reactor for waste water including a vessel 10 having two elongated outer channels 26, 28 sandwiching an elongated inner channel 30 with all the channels 26, 28 and 30 being connected to each other at both opposed ends thereof, a gate 64 at one of the ends 18 and movable between a first position isolating the channel 26 from the channels 28 and 30 and a second position isolating the channel 28 from the channels 26 and 30, rotors 32, 34 for each of the channels 26, 28 for aerating waste water in the vessel 10 and for causing the waste water to flow in the corresponding channels 26, 28 as well as the inner channel 30, and a pair of effluent outlets 98, 100, located at the end 18 and spaced to be on opposite sides of the gate 64, each selectively operable to withdraw effluent from the the outer channels 26, 28 on the associated side of the gate 64.

Abstract: Waste water treatment apparatus including a vessel for receiving the waste water and having an inlet and an effluent outlet spaced from the inlet. The space between the two defines a flow path for the waste water and a scum outlet is also provided for the vessel. An elongated trough having an elongated opening is disposed horizontally in the vessel at an intended level of waste water therein and extends across the flow path. A movable skimmer blade extending below the intended level of waste water can be drawn along the flow path to capture scum and deliver and deposit the same in the trough through the opening thereof.