Abstract: The present invention relates to a process for the anaerobic purification of waste water which comprises a fluidized-bed process in which granular sludge is applied.Moreover apparatus is disclosed for the purification of waste water using a fluidized-bed reactor wherein a liquid introduction device is present which is formed by one or more separate inlet pipes, the pipes delivering the liquid near the bottom of the reactor with an outlet velocity of 0.5-4 m/s, preferably 1-2 m/s.

Abstract: A single unit fluidized-bed reactor having a reaction space for purification of waste water with biomass attached to carrier particles, comprising a liquid distribution device above the bottom of the reaction space particularly suited for introduction of waste water in wide reactors to achieve uniform fluidization therein, said device consisting of a number of substantially horizontal pipes, each having in the under-surface a number of regularly distributed openings for downward introduction of the liquid, and on top of the reaction space united therewith a multifunctional separation compartment for complete separation of the gas-liquid-solids mixture leaving the reaction space and for complete return of attached biomass into the reaction space, the separation compartment being construction so as to handle treatments involving large or small gas fractions in reactors of varying width.

Abstract: An oxidative biological purification process for waste water in a fluidized-bed reactor at a pH between 5 and 8 in the oxidation space comprising passing waste water upwards through an air-sparged oxidation space containing aerobic biomass attached to insoluble carrier particles of a size of 0.1 to 2 mm with a specific gravity of 2 to 5 g/cm.sup.3 at such a rate that space loads of COD of 4-50 kg/m.sup.3 day are achieved while continuously and completely separating purified waste water leaving the oxidation space from said attached aerobic biomass, whereby the aerobic biomass prevails to at least a very substantial extent in a state of attachment to said carrier particles, undue surplus formation of said sludge being minimized by continuous control of the residence time of the waste water to be treated in the oxidation space between the limits of 0.3 to 20 hours, and at least all attached aerobic biomass is recycled to the oxidation space by way of settling.