Filtering method and apparatus.

摘要

A filtering method and apparatus in which a chamber l0 has an inlet l8 and a filtrate outlet l6. A perforated base l4 is mounted within the chamber and a perforated piston 26 is spaced therefrom, the base and the piston extending across the chamber between the inlet and outlet. A mass 34 of fibres fill the space 46 between the base and the piston. Means 24 are provided to move the piston away from and towards the base, to enlarge and reduce the size of the space and a backwash of fluid through the space 46 can take place in a direction away from the base and towards the inlet when the piston is moved back and forth during the backwash operation.