Filter devices and methods

Filter apparatus comprising:

• a circular filter bed,
• rotary blade means positioned above the top surface of said filter bed,
• a shaft to which said blade means is fixed,
• means to rotate said shaft and move said blade means over the top surface of said filter bed, in both a clockwise and counter-clockwise direction,
• said blade means comprising a blade having a first pointed, scraping, longitudinal edge and a second blunt, plowing, longitudinal edge.

A method of filtering influent material prone to form a fluid flow resistant filter cake which comprises:

• providing a flat, horizontal, rigid filter bed,
• flowing influent onto the top surface of said filter bed and causing a filter cake to form on said surface by removal of filtrate from said influent through said filter bed,
• passing a blade over said top surface of said filter bed to lift portions of said filter cake away from said filter bed,
• simultaneously with said lifting of filter cake, applying a vacuum through a porous surface in said blade to the lifted portions of filter cake to effect removal of further filtrate therefrom,
• continuing said blade passing and vacuum applying until a mass of incoherent particles of filtered material is produced, and
• removing said mass of incoherent particles from said filter bed.

Filter apparatus for filtering influent that forms a filter cake appreciably resistant to the passage of filtrate which comprises:

• a flat, rigid, horizontal filter bed,
• a scraper blade having a longitudinal edge in contact with the top surface of said filter bed,
• a porous surface in said scraper blade,
• a means to apply a vacuum through said porous surface, and
• means to move said scraper blade over the surface of said filter bed.