Abstract: A centrifuge of the type having a rotary basket with a bottom wall, side wall and a top wall with a central opening therein includes a liquid feed pipe extending into the basket through the top opening to a point spaced above the basket bottom wall at the rotary axis thereof for conducting a feed liquid into the basket. A feed accelerator projects from the basket bottom wall opposite the feed pipe. The accelerator rotates with the basket so that, the accelerator will impart radial and angular acceleration to the liquid issuing from the feed pipe so that that liquid is redirected and accelerated toward the basket side wall. The centrifuge also incorporates a liquid drain in the basket bottom wall adjacent to the rotary axis of the basket for draining liquid from the basket when the rotation of the basket is stopped.

Abstract: A wastewater treatment system mixes return activated sludge with influent wastewater under anoxic conditions in the presence of luxury uptake organisms to cause release of phosphorous compounds into the surrounding wastewater. The wastewater is then aerated in the presence of nitrifying organisms to convert ammonia into nitrate while the luxury uptake organisms take up the phosphorous compounds. The wastewater is next subjected to alternating anoxic and oxic conditions to reduce the nitrate to nitrogen gas using denitrifying organisms. The resulting effluent is substantially free of nitrogen-based phosphorous-based nutrients.