High Rate Filtration System
A high rate, upflow filtration system is described in which a compressible, fibrous lump filtration media is compressed to adjust the porosity and collector size of the media in the bed and to provide a porosity gradient within the bed proceeding from more porous to less porous in a direction opposite to the flow of fluid so that filtration proceeds in a direction from a more porous to a less porous filter bed. Larger particles are removed by the more porous media and successively smaller particles are removed as the filter bed becomes less porous. The system is capable of reducing the turbidity of influent municipal wastewater from about 8 NTU to about 2 NTU at a wastewater flow rate of from about 820 to 1230 L/m 2 ·min (20 to 30 gal/ft 2 ·min), at a bed compression ration of from about 15 to 40 percent, and at a backwash rate of from about 1 to 6 percent based on the total wastewater passing through the filter.
1 . Filtration apparatus for removing suspended solids from fluids, said apparatus comprising:
a) a filter housing having an axial fluid flow direction therethrough;
b) a first perforated panel fixedly secured in said housing transverse to said axial fluid flow direction;
c) a second perforated panel movably secured in said housing transverse to said axial fluid flow direction and spaced from said first perforated panel;
d) compressible filtration media located between said first and second panels;
e) a piston for moving said second perforated panel toward and away from said fixed first panel to define:
i) a filter bed of said compressible media compressed between said panels during filtration, said filter bed having a porosity gradient across the bed proceeding progressively from more porous to less porous in said axial fluid flow direction; and
ii) a cleaning chamber between said panels during washing wherein said second panel is moved away from said first panel to provide said media in an uncompressed condition for washing; and
f) an influent conduit located adjacent said fixed first panel and in fluid supplying connection with said compressed filter bed and said cleaning chamber; and
g) at least one effluent conduit located adjacent said movable second panel thereby establishing said axial fluid flow direction through said housing from said influent conduit to said at least one effluent conduit, whereby said compressible filtration media is cleaned by its own influent.
2 . Filtration apparatus of claim 1 wherein said influent conduit is connected to a source of fluid containing suspended solids.
3 . Filtration apparatus of claim 1 wherein said source of fluid containing suspended solids is a clarifier.
4 . Filtration apparatus of claim 3 wherein said clarifier is connected to a biological sludge reactor for treating waste water.
5 . A treatment apparatus for removing solids from a fluid, said apparatus comprising:
a) a clarifier for receiving a fluid having suspended and non-suspended solids therein and separating the non-suspended solids from the fluid; and
b) a filter in flow receiving communication with said clarifier for receiving fluid from said clarifier, said filter comprising:
i) at least one filter housing having an axial flow direction therethrough for fluid;
ii) a first perforated panel fixedly secured in said housing transverse to said flow direction;
iii) a second perforated panel movably secured in said housing transverse to said flow direction and spaced from said first perforated panel;
iv) an influent conduit located adjacent said fixed first panel, said influent conduit in flow receiving communication with said clarifier;
v) an effluent conduit located adjacent said movable second panel thereby establishing said axial flow direction through said housing from said influent conduit to said effluent conduit;
vi) compressible filtration media located between said first and second panels; and
vii) a piston for moving said second perforated panel toward and away from said fixed first panel to define:
a) a fixed filter bed of said media compressed between said panels during filtration, said filter bed having a porosity gradient across the bed proceeding progressively from more porous to less porous in said axial flow direction; and
b) a cleaning chamber between said panels during washing wherein said second panel is moved away from said first panel to provide said media in an uncompressed condition for washing in said axial flow direction.
6 . The treatment apparatus of claim 5 wherein said influent conduit is a single influent conduit.
7 . The treatment apparatus of claim 5 further comprising a washing fluid effluent conduit located adjacent said movable second panel.
8 . The treatment apparatus of claim 7 wherein said washing fluid effluent conduit returns the washing fluid for further treatment.
9 . The treatment apparatus of claim 5 wherein said filter is an up-flow high rate filtration apparatus having said fixed first panel located below said movable second panel and wherein said influent conduit is located below said fixed first panel and said effluent conduit is located above said movable second panel.
10 . The treatment apparatus of claim 5 wherein said compressible filtration media in said filter comprises substantially spherical individual fibrous lumps of crimped and bundled fibers.
11 . The treatment apparatus of claim 5 wherein said filter further comprises at least one gas injection conduit located adjacent said first fixed panel for supplying air to said cleaning chamber to mechanically shear trapped solids from said media in said cleaning chamber.
12 . The treatment apparatus of claim 5 wherein said filter further comprises a pair of gas injection conduits located on opposite sides of said housing adjacent said first fixed panel whereby gas injection into said cleaning chamber in said axial flow direction is alternated between said conduits to increase the mechanical effect of shearing trapped solids from said media.
13 . The treatment apparatus of claim 5 wherein said filter comprises multiple filter housings each having independently operated influent and effluent conduits and movable second panels wherein filtration media in one or more filter housings can be washed independently of other filter housings.