The invention provides a mixer feeder (1) comprising a mobile chassis (3), a tub (4) provided on the chassis (3) and at least one auger provided for rotation about a respective vertical axis of rotation. in the tub (4). Seen in vertical cross-section, the wall (12) of the tub (4) extends at least substantially upright from the bottom (6) of the tub (4). The wall (12) of the tub (4) curves inward at the upper side of the tub (4), sloping up and then extending downward.

The confined plunging liquid jet reactor with modified downcomer includes a downcomer having an upper end, an open lower end, and a gas inlet for receiving gas. A plurality of longitudinally-extending baffles and/or a sieve are mounted in the downcomer, adjacent the open lower end thereof. A nozzle is mounted on the upper end of the downcomer for receiving a pressurized liquid from an external source to generate a liquid jet. The liquid jet impinges on liquid contained within the downcomer creating turbulence and bubbles with the gas entrained therein. The open lower end of the downcomer is positioned within a receiving tank holding a reservoir of the liquid such that a portion of the mixture of the liquid and the gas exits the open lower end of the downcomer to flow into the receiving tank.

The invention provides a mixer feeder (1) comprising a mobile chassis (3), a tub (4) provided on the chassis (3) and at least one auger provided for rotation about a respective vertical axis of rotation. in the tub (4). Seen in vertical cross-section, the wall (12) of the tub (4) extends at least substantially upright from the bottom (6) of the tub (4). The wall (12) of the tub (4) curves inward at the upper side of the tub (4), sloping up and then extending downward.