Process and device for the filtration of liquids polluted by suspended solid bodies

Claim 3

A device according to claim 1 whereby said first and second filter bed are both formed of a buoyant filter material having a specific gravity substantially no greater than that of water and wherein said first filter bed is comprised of granules of larger size than said second filter bed.

Claim 4

A device according to claim 2 wherein means are provided for passing liquid to be filtered first upwardly through said larger granular size filter bed and thereafter upwardly through said second filter bed.

Claim 5

A device according to claim 1 wherein said second filter bed is formed of a filter material having a specific gravity substantially greater than said first filter bed material and wherein means are provided for passing liquids to be filtered sequentially first upwardly through said first filter bed and thereafter downwardly through said second filter bed.

Claim 6

A process for filtering liquids containing suspended solids in a device having a substantially vertical cylindrical container divided into a top and bottom chamber by a non-porous plate member arranged in a fixed and immovable position transversely of said container, at least the top chamber further divided into an upper and lower section by a porous plate member arranged in a fixed and immovable position transversely of said top chamber, at least the upper portion of the side walls of the said lower section formed into a truncated cone shaped portion along its verticle axis with the smaller diameter end of said truncated cone shaped portion arranged adjacent the said porous fixed plate member, a first filter bed located in said lower section of said top chamber and a second filter bed separately located in said bottom chamber, the process comprising passing the said liquid in an upwardly direction through said first filter bed at a velocity sufficient to compact the filter material into a bed or pack disposed within and occupying said truncated cone shaped chamber, said filter material formed of particles having a specific gravity no greater than the said liquid being filtered, the top smaller diameter end of said truncated cone shaped chamber being permeable to the passage of liquid there through but not to the filter material, passing the effluent in series flow from said first filter bed through fluid conduit means positioned internally of said cylindrical container and passing directly through said non-porous plate member to the other chamber and through the second filter bed contained therein and removing the effluent from said second filter bed as twice filtered liquid, thereafter backwashing each of said filter beds by flowing backwashing liquid in a direction opposite to the direction employed in the filtration step and at a flow rate sufficient to cause the temporary expansion of said first filter bed to result in the separation and removal of filtered solids.

Claim 7

A process for filtering liquids containing suspended solids in a device having a substantially vertical cylindrical container divided into a top and bottom chamber by a non-porous plate member arranged in a fixed and immovable position transversely of said container, at least the top chamber further divided into an upper and lower section by a porous plate member arranged in a fixed and immovable position transversely of said top chamber, at least the upper portion of the side walls of the said lower section formed into a truncated cone shaped portion along its verticle axis with the smaller diameter end of said truncated cone shaped portion arranged adjacent the said porous fixed plate member, a first filter bed located in said lower section of said top chamber and a second filter bed separately located in said bottom chamber, the process comprising passing the said liquid in an upwardly direction through said first filter bed at a velocity sufficient to compact the filter material into a bed or pack disposed within and occupying said truncated cone shaped chamber, said filter material formed of particles having a specific gravity no greater than the said liquid being filtered, the top smaller diameter end of said truncated cone shaped chamber being permeable to the passage of liquid there through but not to the filter material, passing the effluent in series flow from said first filter bed through fluid conduit means positioned internally of said cylindrical container and passing directly through said non-porous plate member to the other chamber and through the second filter bed contained therein and removing the effluent from said second filter bed as twice filtered liquid, thereafter backwashing each of said filter beds by flowing backwashing liquid in a direction opposite to the direction employed in the filtration step and at a flow rate sufficient to cause the temporary expansion of said first filter bed to result in the separation and removal of filtered solids.