Abstract: Present invention relates to a method and apparatus for purification of water, said method comprises the steps of feeding the water into a reactor (4) through one or more inlet tubes (1) or inlet zones and feed water an substrate through carrier elements for bio film (5) which have a large protected surface (>200 m2/m3 carrier elements) and large pore volume (>60%), and that the carrier elements are fluidized for the removal of waste sludge, wherein the ratio of charge of the elements (5) by normal duty corresponds to an amount corresponding to 90%-100%, more preferred 92%-100%, and most preferred 92%-99% of the vet volume of the reactor (4), said carrier elements (5) is kept substantially at rest or hindered movement between the times surplus sludge is removed, and that the carrier elements being fluidised for removal of surplus sludge, said carrier elements (5) having a specific gravity in the area of 0.8-1.4, more preferred 0.90-1.1 and most preferred 0.93-0.

Abstract: It is described a method for biological purification of water, the method comprising: leading the water into a reactor through one or more inlet pipes or inlet zones; leading the water and substrate through carrier elements for biofilm growth which have a high protected surface area (>200 m2/m3 carrier elements) and a large pore volume (>60%); wherein one or more membrane units are submerged in the water in the reactor; wherein permeate is pulled out of the reactor through the pores of the membranes; wherein oxygen-containing gas is supplied in the reactor through an aeration system; wherein during normal operation the water level in the reactor is maintained below one or more outlet pipes or outlet zones that are dedicated for excess sludge removal; wherein during washing operation strong turbulence is created for removal of excess sludge as the water level in the reactor is temporarily raised to the level where the outlet pipes or outlet zones that are dedicated for excess sludge removal are.

Abstract: The invention relates to a reactor for treatment of waste water for being subject to both anoxic/anaerobic and aerobic treatment within one single reactor volume. The anoxic/anaerobic reaction zone is separated from the aerobic reaction zone by a separator which also works as a hydrodynamic separator between the two reaction zones. The reactor makes it possible that the effluent water has a lower proportion of suspended solids and also that it produces less sludge than reactors of comparison. The reactor is further more energy efficient than prior art reactors. Several reactors according to the invention may be arranged in parallel so as for the inlet waste water may be treated in a modular way, and thus allowing the maintenance of the units to be facilitated.