WASTEWATER CONCENTRATION

1365078 Screening apparatus SWECO Inc 28 May 1971 [1 June 1970 (3)] 6621/74 Divided out of 1365077 Heading B1D A centrifugal screening apparatus comprises a rotary outward flow cylindrical screen in the centre of which is an inlet pipe 12 for influent suspension. Above the end of the inlet pipe there is a horizontal deflector plate 13 which deflects the influent downwards onto a distribution dome 18. The deflector plate is vertically movable relative to the inlet pipe so as to vary the size of the inlet orifice formed between the end of the inlet pipe and the deflector and thus control the rate of influent flow. The screw-like distribution dome 18 has inclined blades (Fig. 5, not shown) which directs the influent onto the rotating screen. Filtered liquid collects in annular chamber 67 and is removed via pipe 15. Solids fall into chamber 68 and are removed via pipe 16, the filtering conditions being adjusted so that the solids fraction retains sufficient liquid for it to flow. Influent which spashes back from the screen is collected in chamber 71 and returned to the inlet for further screening. The cylindrical screen may be formed by a number of flat screen panels locked into a frame (Fig. 7, not shown). Screen cleaning is achieved by nozzles 82, 83 on supply pipes 80, 81, the cleaning operation being carried out periodically.