Process and equipment for the purification of liquids by filtration

Claim 1

Apparatus for filtering liquids, comprising an upright column of filter particles, inner and outer foraminous walls bounding said column of filter material on opposite sides, wherein the improvement consists in the provision of a guiding pipe closed at its top and open at its bottom inside of said inner foraminous wall and coaxial therewith, said inner wall being comprised by a plurality of shutters in the form of spaced overlapping plates inclined downwardly outwardly and said outer wall being impermeable to the filter material, the guiding pipe and said inner foraminous wall forming a liquid distributor chamber of annular cross-sectional area, this liquid distributor chamber being connected with an inlet duct for crude water, a downwardly tapering distributor vessel for wash water under the filter column, a tube connected to said wash water distributor vessel for conducting wash water thereinto, said vessel having passages for introducing wash water into said filter column, a conical sand collector chamber disposed beneath the guiding pipe and liquid distributor chamber, and an air lift extending from adjacent the bottom of said sand collector chamber to the top of the apparatus.