A method and an apparatus for treating a liquid containing impurities may include a filtering chamber configured to permit granular media to interact with liquid containing impurities, thereby removing impurities from the liquid to produce filtrate; a filtrate section for receiving the filtrate; a gas supplying system for delivering gas to the granular media in the filtering chamber for transport of a portion of the granular media to a granular media washer; a reject section in fluid communication with the granular media washer for receiving a reject mixture comprising liquid and impurities from the granular media washer; and a control unit that is configured to determine whether the portion of the granular media is being transported properly based on an amount of reject mixture in the reject section.

The present document describes a media bed filter for filtering fine particles from a raw liquid flow, the media bed filter comprising: a tank having: a top portion; a bottom portion defining a bottom surface for receiving a media bed, the media bed having a supporting media to be disposed on the bottom surface and a filtering media for covering the supporting media, the top portion of the tank being above the filtering media of the media bed; a raw liquid inlet in fluid communication with a nozzle configuration located in the top portion of the tank for providing the raw liquid flow in the tank in the form of a plurality of jets at a directional velocity substantially equal or greater to a disengagement velocity of the filtering media.