Abstract: A biological process for removing biochemical oxygen demand from waste water by forming a fluidized bed of microorganisms attached to a solid particulate carrier, continuously passing waste water to be treated through said fluidized bed, retaining the waste water in the fluidized bed for a sufficient period of time while controlling other necessary parameters to biologically convert substantially all of the biochemical oxygen demand to be removed from the waste water to methane gas, carbon dioxide and cellular material, and thence withdrawing the biologically converted products. In one form of the invention nitrified effluent is added to the waste water and the mixture is biologically converted to methane gas, carbon dioxide, nitrogen gas and cellular material.

Abstract: Process for removing organic carbon from waste water to reduce biochemical oxygen demand by generating a fluidized bed formed from biota attached to a solid particulate carrier and waste water, providing enough oxygen to allow the biota to reduce the biochemical oxygen demand of the waste water passing therethrough and then mechanically removing excess bacterial growth formed on the carrier during the process.

Abstract: A biological process for removing ammonia nitrogen from waste water by forming a fluidized bed of microorganisms attached to a solid particulate carrier, continuously passing waste water to be treated through said fluidized bed, adding oxygen to said fluidized bed, retaining the waste water in the fluidized bed for a sufficient period of time while controlling other necessary parameters to biologically convert substantially all of the ammonia nitrogen to be removed from the waste water to oxidized forms of nitrogen, water and cellular material, and thence withdrawing the biologically converted products from the fluidized bed. In another form of the invention apparatus is provided for effecting the foregoing process.

Abstract: Process and apparatus for removing organic carbon from waste water to reduce biochemical oxygen demand by generating a fluidized bed formed from biota attached to a solid particulate carrier and waste water, providing enough oxygen to allow the biota to reduce the biochemical oxygen demand of the waste water passing therethrough and then mechanically removing excess bacterial growth formed on the carrier during the process.

Abstract: An apparatus for denitrifying waste water including means for: generating a fluidized bed containing denitrifying biota on a particulate carrier, metering a carbon source into the waste water and mechanically removing excess bacterial growth from the carrier at predetermined intervals.