Conservation of momentum in a barrier oxidation ditch

A mixing-control apparatus which comprises, in combination with an endless channel of a closed-circuit oxidation ditch:

• (a) a barrier, sealably attached to the bottom and sides of said channel, for dividing said channel into an intake channel portion and a discharge channel portion, said barrier having at least one aperture therethrough for providing substantially translational fluid flow communication between said intake channel and said discharge channel, thereby conserving momentum of fluid flowing is said channel by enabling induced fluid-flow therebetween;
• (b) means for adjustably opening and closing said at least one aperture;
• and
• (c) at least one pump assembly which comprises a motor having a shaft, an impeller attached to said shaft, and a discharge duct within which said impeller operates and which has an intake end and a discharge end, said intake end being within said intake channel portion and said discharge end being within said discharge channel portion thereby enabling a pumped fluid-flow therebetween.