WO1998018537A1

WO1998018537A1 - System and method for treatment of liquids

Info

Publication number: WO1998018537A1
Application number: PCT/US1997/019579
Authority: WO
Inventors: Victor M. Yacobi
Original assignee: Water Petroleum & Environmental Technologies Co
Current assignee: Water Petroleum & Environmental Technologies Co
Priority date: 1996-10-29
Filing date: 1997-10-28
Publication date: 1998-05-07
Anticipated expiration: 1999-04-29
Also published as: AU5003797A

Abstract

A system for treating a process liquid, such as water, by removing from the process liquid various components. These components may include oil products. In addition, the system can be adapted to remove other contaminants, such as other liquid contaminants and solid-suspended contaminants, such as sludge and flocs. The system includes a process tank (40) for holding the process liquid, and a filter chamber (30) rotatably mounted in the process tank. Fluid communication is provided between the process tank and the filter chamber's interior through the filter chamber's periphery (32), and between the filter chamber's interior and a first outlet valve (44). A porous filter medium, preferably made from resiliently deformable material, is located in the interior of the filter chamber. In a preferred embodiment, this filter material mechanically filters suspended solids, such as sludge, from the process liquid, and also absorbs into the filter material itself insoluble contaminants, such as oil. The system preferably includes a motor for spinning the filter chamber, so as to regenerate the filter medium. In a preferred process, the treated liquid provides a backwash to regenerate the filter medium by passing back from the first outlet valve through the filter medium into the process tank. This process causes mechanically filtered solids to be removed from the filter medium. To remove liquid contaminants, such as oil, the filter chamber is spun at a higher speed.

Description

SYSTEM AND METHOD FOR TREATMENT OF LIQUIDS

This application claims priority from provisional application serial no. 60/029,777 filed October, 29, 1996, which is incoφorated herein by reference.

DESCRIPTION Summary of the Invention The present invention is directed to systems and processes for treating a process liquid-such as water— by removing from the process liquid various components. These components may include oil products. In addition, the system can be adapted to remove other contaminants, such as other liquid contaminants and solid-suspended contaminants, such as sludge and floes. The system includes a process tank for holding the process liquid, and a filter chamber is preferably rotatably mounted in the process tank. Fluid communication is provided between the process tank and the filter chamber's interior through the filter chamber's periphery, and between the filter chamber's interior and a first outlet valve. A porous filter medium, made from resiliently deformable material, is located in the interior of the filter chamber. In a preferred embodiment, this filter material absorbs into the filter material itself insoluble contaminants, such as oil and other oil products, as well as mechanically filtering suspended solids, such as sludge, from the process liquid. In order to absorb oil, the material preferably comprises polyurethane foam, wherein the polyurethane foam which is pre-treated with an oleophilic agent in order to enhance the oil absorption capacity of the foam, and then compressed in order to remove excess pre- treatment agent.

An inlet valve may be used to control the flow of untreated liquid into the process tank, a first outlet valve may be used to control the flow of treated liquid from the filter chamber's interior, and a second outlet valve may be used to control the flow of liquid from the process tank. The system preferably includes a motor for spinning the filter chamber, so as to regenerate the filter medium. A controller controls the inlet valve, the first and second outlet valve, and the motor. In a preferred process, the treated liquid provides a backwash to regenerate the filter medium by passing back from the first outlet valve through the filter medium into the process tank, while the inlet valve is closed. This process causes mechanically filtered solids to be removed from the filter medium. Preferably, this process takes place while the filter chamber is being spun.

In a preferred embodiment, the system further includes, downstream of the second outlet valve, separation filter means for separating a first component (e.g., the solid suspended contaminants) from the process liquid and means for collecting a second component (e.g., oil) in the liquid. In such an embodiment, the second outlet valve, when it is open, preferably directs liquid from the process tank, either to the separation filter means or to the means for collecting a second component from the liquid. The liquid passing from the separation filter means may then be directed eventually back to the inlet valve.

The controller, in this embodiment of the system, opens the first outlet valve to permit treated liquid to pass back from the first outlet valve (to provide backwash), through the filter medium into the process tank, while the inlet valve is closed and while the filter chamber is being spun at a relatively low rotational speed, so as to cause the first component to separate from the filter chamber and the filter medium, so that liquid and the first component may pass through the second outlet valve. After substantially all of the first component passes through the second outlet valve, the filter chamber may be spun at a higher rotational speed, while the inlet valve is closed. This step causes a second component, which had been absorbed by the filter medium, to be forced out of the filter medium.

In one embodiment, the process tank may be separated into two compartments. An upper compartment may hold treated liquid from the filter chamber's interior for output through the first outlet valve. The lower compartment may contain the filter chamber, the inlet valve, and the second outlet valve.

In a preferred embodiment, the system includes two additional treatment tanks, one of which has an outlet connected to the inlet valve of the process tank, and means for chemically treating the liquid so as break chemical emulsions, and the other of which has an inlet, which is connected to the first outlet valve, and material for further filtering of treated liquid from first tank. This material may include volcanic material or activated carbon. In another embodiment, the system includes two process tanks in a row. In the first of these tanks, a filter chamber absorbs a component (such as oil or other oil product) from the liquid; the liquid is treated so that more of that component or another component coalesces into floes or another type of suspended solid; then, in the second tank, a second filter chamber filters the floes or other type of suspended solid from the liquid. The first filter chamber may be regenerated by spinning the filter chamber at a relatively high speed, and the second filter chamber may be regenerated by spinning the filter chamber at a relatively low speed while the treated liquid is passed back through the second filter chamber, providing a backwash.

Description of the Drawings FIG. 1 shows a preferred embodiment of a system according to the present invention, wherein three treatment tanks are used: a pretreatment tank, a contaminant- removal tank and a fine-treatment tank.

FIG. 2 shows a vertical sectional view of the contaminant-removal tank in the filtering mode.

FIG. 2A shows a cross- sectional view of the contaminant-removal tank. FIG. 3 shows a vertical sectional view of the contaminant-removal tank of FIG. 2 in the backwash-collection mode.

FIG. 4 shows a vertical sectional view of the contaminant-removal tank of FIG. 2 in the pre-backwash mode.

FIG. 5 shows a vertical sectional view of the contaminant-removal tank of FIG. 2 in the first regeneration mode. FIG. 6 shows a vertical sectional view of the contaminant-removal tank of FIG. 2 in the second regeneration mode.

FIG. 7 shows a vertical section of an alternative contaminant-removal tank. FIG. 7 A shows a cross-sectional view of the tank shown in FIG. 7. FIG. 8 shows a cross- sectional view of a compartmentalized filter cartridge. Detailed Description of Specific Embodiments FIG. 1 shows a preferred embodiment of the present invention, wherein three treatment tanks are used. The untreated liquid, also referred to herein as effluent, which may be water with emulsified oil and sludge, is initially stored in a tank 14. The effluent is then pumped from the tank into the pretreatment tank 10 through inlet 12. In the pretreatment tank 10, the effluent is chemically treated to break-up chemical emulsions. The pre-treated effluent is then pumped from the pretreatment tank's outlet 16 by pump 18 to the inlet 22 of the contaminant- removal tank 40, also called the process tank. The process tank 40, removes the oil and sludge contaminants from the water. The treated water exits the process tank 40 through its outlet valve 44, and the treated water is then routed to the inlet 92 of the fine-treatment tank 90.

The fine-treatment tank 90 contains activated carbon and/or volcanic material and/or broken brick. After passing through this material, which filters out some additional contaminants from the water, the treated water passes through the outlet 94 of the fine-treatment tank 90 to a tank 96 for holding the treated water. As indicated in FIG. 1 , the fine-treatment tank may be bypassed, so that water may flow directly from the process tank 40 to the holding tank 96 for the treated water.

FIG. 2 shows an embodiment of the process tank 40 in greater detail. The tank 40 is divided into an upper compartment 42 and a lower compartment 20, which are divided by a divider plate 28, which is imperforate except for a hole through which a shaft 36 passes. Thus, liquid may not pass between the upper and lower compartments, 42 and 20, except through the shaft 36.

During the normal filtering mode, effluent is pumped to the inlet valve 22. As shown in FIG. 2A, the inlet valve 22 includes a nozzle that directs the effluent tangentially around the lower compartment 20 of the tank 40. Pump 18 (shown in FIG. 2) provides the effluent under pressure to the lower compartment 20. A chemical injector pump 23 may also pump into the lower compartment chemicals for further treatment of the effluent.

In the lower compartment 20 is a filter chamber 30, which is cylindrical in shape. The filter chamber 30 contains a porous, resilient filter medium. This filtering medium preferably includes granulated polyurethane foam pieces that are pre-treated with an oleophilic agent; such an agent may be oil (such as 20W-40 oil), and may be used to treat the foam pieces in such a way that all internal capillaries, as well as external surfaces are covered with a thin film of oil. In order to accomplish this, the foam pieces may be soaked in the pretreatment oil and then compressed so as to remove all of the excess pretreatment oil. In a preferred embodiment, the foam pieces are roughly cube-shaped with a volume of about 1 cubic cm (or 1 cubic inch), and have a packing density of up to 200 kg/m³, preferably between 100 kg/m³ and 200 kg/m³. Preferably, the polyurethane foam is made with open and semi-open cells. In an embodiment, shown in FIG. 8, the filter chamber 30, may be a replaceable cartridge assembly, which may simplify maintenance. Such a cartridge assembly, in a further embodiment, may be partitioned into compartments.

When the lower compartment 20 is full of effluent, the effluent will start to pass through the filter medium in the filter chamber 30. In the preferred embodiment, the upper and lower walls of the filter chamber 30 are solid and the perimeter wall 32 perforate, so that effluent must pass through the perimeter wall 32. An interior perforate wall 34 holds the filter medium in an annular volume and provides an open volume 35, which may hold a volume of filtered liquid.

The pressure generated by the pump 18 forces the liquid through the filter medium and up the hollow shaft 36 into the upper compartment 42. During the normal filtering mode, the outlet valve 44 is open so that the treated liquid may pass to a holding tank or to another tank for further treatment. The outlet valve 44 is mounted some distance above the divider plate 28, so that some amount of treated liquid may be collected in the upper compartment to be used during the first regeneration mode as backwash.

In a preferred embodiment of the invention, the normal filter mode shown in FIG. 1 lasts approximately six uninterrupted hours. After about six hours, the filter medium in the filter chamber 30 needs to be regenerated. The regeneration uses centrifugal force and backwash liquid to remove the sludge and oil from the filter medium. First the sludge is removed, using backwash liquid and a relatively small amount of centrifugal force. After all the backwash liquid passes through the filter medium and the sludge is removed from the filter medium, a relatively large amount of centrifugal force is used to remove the oil- products from the cubes. In order to collect additional backwash liquid in the upper chamber 42, the outlet valve 44 is closed, as shown in FIG. 3. The closing of the outlet valve 44 causes additional treated liquid to accumulate in the upper compartment 42. After a sufficient amount of treated liquid is accumulated in the upper compartment 42, the pump 18 is turned off and the inlet valve 22 is closed, as shown in FIG. 4. The effluent valve 52 is opened to allow the untreated effluent in the lower compartment 20 to be evacuated before the regeneration process is begun. The untreated effluent passes through the drain 50 at the bottom of the lower compartment, through the effluent valve, through the replaceable sludge filter to the effluent holding tank 14 (shown in FIG. 1), where it is held until the regeneration process is completed, at which point it is passed through the pretreatment tank 10 to the process tank 40 again for treatment. During the evacuation of untreated effluent from the lower compartment 20, the vacuum valve 46 in the upper compartment is opened so that a vacuum does not develop in the top of the tank 40 thereby preventing fluid from flowing out of the tank 40. However, a sufficient amount of treated liquid is allowed to remain in the upper compartment 42 and the interior volume 35 of the filter chamber 35 for the actual regeneration procedure.

FIG. 5 shows the first part of the regeneration procedure, wherein the sludge is removed from the filter medium. The motor 38 is turned on at low speed— in a preferred embodiment at approximately 300-400 rpm. The motor 38, as well as the valves and pumps, are controlled by a controller, preferably a digital processor 19, as shown in FIG. 1. The motor 38 turns the shaft 36, which is rotatably mounted in the tank 40. The filter chamber 30 is attached to the shaft 36, so that the filter chamber turns with the shaft. The backwash liquid continues to pass from the upper chamber 42 through the shaft 36 and into and through the filter medium in the filter chamber 30, while the chamber is being rotated slowly. The mechanical action of the centrifugal force and the flow of backwash liquid removes the sludge from the filter medium and the filter chamber. This sludge then passes through the drain 50 at the bottom of the lower compartment and through the effluent valve 52, which is opened. The liquid passes through the replaceable sludge absorber 56, which catches the sludge. The liquid passing through the sludge absorber 56, which liquid typically includes water and oil, is returned to the tank 14 for holding untreated effluent. This liquid may then be treated in the next cycle. After all the backwash liquid passes through the filter chamber, substantially all of the sludge should have been removed from the lower compartment 20. At this point, the system may move into the next regeneration phase, the removal of oil from the filter medium. The effluent valve 52 is closed and the oil valve 54 is opened, and the motor 38 causes the filter chamber 30 to be rotated at a higher speed, preferably about 900-1200 rpm. The higher centrifugal force created by this high rotational speed forces the oil absorbed by the filter medium out of the filter medium. This oil, after being forced out of the filter medium, passes through the drain 50 and the oil valve 54 to the tank for holding oil 58 (in FIG. 1). After a sufficient amount of oil has been forced out of the filter medium, the motor 38 is turned off, the oil valve 54 closed, the vacuum valve 46 closed, the inlet valve 22 and the outlet valve 44 opened, the effluent pump 18 turned on and the chemical injector pump 23 turned on. These actions put the system back into the normal filter mode shown in FIG. 1. The entire regeneration process only takes several minutes, whereas the normal filter mode should last, in a preferred embodiment, approximately several hours.

In an alternative embodiment, shown in FIG. 7, the upper compartment 42 of the process tank 40 may be reduced in size or eliminated. During the normal filtering mode of such a system, effluent is pumped into the process tank 40 through the inlet valve 22. A pump may provide the effluent under pressure to the inlet valve 22. A chemical injector pump may also pump into the lower compartment chemicals for further treatment of the effluent. As shown in FIG. 7 A, the inlet valve 22 nozzle directs the effluent tangentially around the outer portion of the process tank 40. Returning to FIG. 7, when the process tank 40 is full of effluent, the pressure generated by the pump will force the effluent liquid through the annular volume of the filter medium in the filter chamber 30. From the interior of the filter chamber 30, filtered liquid flows up the hollow shaft 36 and out from the process tank 40 through outlet valve 44.

Operation of such a system during regeneration modes would be similar to that described previously, except that the backwash liquid would be flowing directly from the outlet valve 44 and back down through the hollow shaft 36. After about several hours of operation in the normal filtering mode, the filter medium in the filter chamber 30 needs to be regenerated. The inlet valve 22 is closed. The effluent valve 52 is opened to allow the untreated effluent in the process tank 40 to be evacuated before the regeneration process is begun. The untreated effluent passes through the drain 50 at the bottom of the process tank, through the effluent valve, through the replaceable sludge filter to the effluent holding tank. Filtered, treated liquid is then pressurized to a higher pressure than that of the liquid in the process tank 40. This causes a backwash of treated liquid to flow back into the process tank through outlet valve 44. At the same time, the controller causes the motor 38 to turn the filter chamber 30 at low speed. The backwash liquid then flows through the hollow shaft 36, through the interior of the filter chamber 30. The backwash then dislodges solid contaminants from the filter medium, and the resulting sludge passes out of the process tank 40 through the drain 50, and through the effluent valve 52. After substantially all of the sludge is removed from the process tank 40, the system proceeds through the second phase of the regeneration procedure as previously described to remove oil from the filter medium and then return back to the normal filter mode.

In another embodiment, the inlet 12 to the pretreatment tank 10, depicted in FIG. 1, would be treated liquid from the outlet of an earlier process tank; in effect, placing two process tanks in series. In such an arrangement, the first process tank may be operated in various modes so as to separate out free and mechanically emulsified oil. The treated liquid from outlet of the first process tank may then be directed to the inlet of a pretreatment tank 10 (in FIG. 1) for the addition of chemical reagents designated for breaking chemically emulsified oil if the treated liquid contains this component as well before directing the liquid to the inlet valve 22 of the second process tank 40. The chemical reagents may create floes suspended in the water. These floes may be removed by the second process tank by using backwash and a slower rotational speed of the filter chamber in much the same way as the sludge is removed in FIGS. 2, 3, and 4. This second process tank may then be operated in various modes, in combination with the added chemical reagents, to remove chemically emulsified oil and contaminants.

One example of an application of this invention would be for separating free and mechanically emulsified oil from industrially-used water. In such an application, the invention may have the following characteristics: Input flow - 2000 ppm oil Output flow - 20 ppm oil Filter medium type - Reticulated, open-pore polyether polyurethane foam

True volume density - 20 kg/m³

Packing density - 70 kg/m³

Cellular linear density - 25 cells/cm Filter chamber diameter - 28 inches

Optimal operational speed for separating sludge and suspended solids - 300 rpm

Optimal operational speed for separating oil products - 1200 rpm

Volume of backwash stream - minimal

Period of filtration mode for 20 gpm stream - 4 hours Filter medium lifetime - 6 months

Another example of an application of this invention would be for separating tramp oil from coolant emulsion. In such an application, the invention may have the following characteristics:

Filter medium type - Non-reticulated, open-pore polyether polyurethane foam True volume density - 20 kg/m³

Packing density - 150 kg/m³

Cellular linear density - 35 cells/cm

Optimal operational speed - 900 rpm

Volume of backwash stream - 0 Period of filtration mode for 20 gpm stream - 48 hours

Filter medium lifetime - 3 to 6 months

A different example of an application of this invention would be for separating free, mechanically emulsified, and chemically emulsified oil in two stages from industrially-used water. In such an application, the invention may have the following characteristics:

Separating free and mechanically emulsified oil in the first process tank

Input flow - 7000 ppm fats, oil and grease (FOG)

Output flow - 2000 ppm FOG

Packing density - 50 kg/m³ Cellular linear density - 25 cells/cm

Optimal operational speed for separating suspended solids - 300 rpm Optimal operational speed for separating oil products - 1200 rpm Volume of backwash stream - minimal Period of filtration mode for 20 gpm stream - 4 hours Filter medium lifetime - 3 months

Breaking chemical emulsion and separating suspended contaminants in the second process tank Input flow - 2000 ppm FOG

Output flow - 20 ppm FOG

Chemicals used for breaking emulsions - preferably metallic salts (e.g., aluminum sulfate, ferrous sulfate, ferric sulfate, ferric chloride, etc.)

Packing density - 40 kg/m³

Cellular linear density - 25 cells/cm

Optimal operational speed - 300 rpm

Volume of backwash stream - maximal Period of filtration mode for 20 gpm stream - 4 hours

Filter medium lifetime - 3 months

Although the invention has been described with reference to several preferred embodiments, it will be understood by one of ordinary skill in the art that various modifications can be made without departing from the spirit and the scope of the invention, as set forth in the claims hereinbelow.

Claims

I claim:

1. A system for treating a process liquid by removing components from the process liquid, the system being of the type having a tank for holding the process liquid and having an inlet means for untreated process liquid to enter the tank, first outlet means for treated liquid to leave the tank, and second outlet means, a filter chamber rotatably mounted in the tank and having an interior and a periphery, wherein fluid communication is provided between the tank inlet means and the filter chamber's interior through the filter chamber's periphery, and between the filter chamber's interior and the tank's first outlet means, means for spinning the filter chamber, a porous filter medium located in the interior of the filter chamber, and a controller for controlling the first and second outlet means, wherein the first outlet means controls the flow of treated liquid from the interior of the filter chamber, and wherein the second outlet means controls the flow of liquid from the portion of the tank exterior to the filter chamber, characterized in that the spinning means includes means for spinning the filter chamber at different speeds, and further characterized by means, controlled by the controller, for causing a backwash of treated liquid to pass through the filter medium into the portion of the tank exterior to the filter chamber, to the second outlet means, while the inlet means is closed, and while the controller causes the spinning means to spin the filter chamber.

2. A system according to claim 1, wherein the tank is divided into two compartments, such that a first compartment contains the filter chamber and the untreated process liquid, a second compartment contains filtered liquid from the first compartment.

3. A system according to claim 1, wherein the backwash of treated liquid comes from the first outlet means.

4. A system according to claim 1, further including means, controlled by the controller, for causing the backwash of treated liquid to occur during the slowest of the plurality of spinning speeds.

5. A system according to claim 1, wherein the filter chamber is a removable cartridge assembly.

6. A system according to claim 1, wherein the filter chamber is partitioned into a plurality of chambers.

7. A system for treating a process liquid by removing components from the process liquid, the system being of the type having a tank for holding the process liquid and having an inlet means for untreated process liquid to enter the tank, first outlet means for treated liquid to leave the tank, and second outlet means, a filter chamber mounted in the tank and having an interior and a periphery, wherein fluid communication is provided between the tank inlet means and the filter chamber's interior through the filter chamber's periphery, and between the filter chamber's interior and the tank's first outlet means, a porous filter medium located in the interior of the filter chamber, and a controller for controlling the first and second outlet means, wherein the first outlet means controls the flow of treated liquid from the interior of the filter chamber, and wherein the second outlet means controls the flow of liquid from the portion of the tank exterior to the filter chamber, characterized in that the second outlet means has a first mode for directing a first component along a first-component pathway, and a second mode for directing a second component along a second-component pathway.

8. A system according to claim 7, further including means, controlled by the controller, for causing, during the first mode, a backwash of treated liquid to pass through the filter medium into the portion of the tank exterior to the filter chamber, to the second outlet means, while the inlet means is closed.

9. A system according to claim 8, wherein the filter chamber is rotatably mounted in the tank and further including means for spinning the filter chamber, and wherein the spinning means includes means for spinning the filter chamber at different speeds, and wherein the controller causes the spinning means to spin the filter chamber at a plurality of speeds.

10. A system for treating a process liquid by removing components from the process liquid, the system being of the type having a tank for holding the process liquid and having an inlet means for untreated process liquid to enter the tank, first outlet means for treated liquid to leave the tank, and second outlet means, a filter chamber mounted in the tank and having an interior and a periphery, wherein fluid communication is provided between the tank inlet means and the filter chamber's interior through the filter chamber's periphery, and between the filter chamber's interior and the tank's first outlet means, a porous filter medium located in the interior of the filter chamber, and a controller for controlling the first and second outlet means, wherein the first outlet means controls the flow of treated liquid from the interior of the filter chamber, and wherein the second outlet means controls the flow of liquid from the portion of the tank exterior to the filter chamber, characterized in that the system further comprises: an inlet tank for containing unprocessed liquid supplied to the processing tank through the inlet means, an outlet tank for receiving filtered, treated liquid from the first outlet means, and means to direct the flow of liquid from the second outlet means back to the inlet tank.

11. A system according to claim 10, wherein the outlet tank includes material for further filtering the treated liquid from the first outlet means.

12. A system according to claim 11 , wherein the material for further filtering is volcanic material.

13. A system according to claim 11, wherein the material for further filtering is activated carbon.

14. A system for treating a process liquid by removing components from the process liquid, the system being of the type having a tank for holding the process liquid and having an inlet means for untreated process liquid to enter the tank, first outlet means for treated liquid to leave the tank, and second outlet means, a filter chamber mounted in the tank and having an interior and a periphery, wherein fluid communication is provided between the tank inlet means and the filter chamber's interior through the filter chamber's periphery, and between the filter chamber's interior and the tank's first outlet means, a porous filter medium located in the interior of the filter chamber, and a controller for controlling the first and second outlet means, wherein the first outlet means controls the flow of treated liquid from the interior of the filter chamber, and wherein the second outlet means controls the flow of liquid from the portion of the tank exterior to the filter chamber, characterized in that the system further comprises: means for chemically treating the liquid from the first outlet means of the first tank so as break chemical emulsions; a second tank, having: second-tank inlet means, which is connected, directly or indirectly, to the first outlet means of the first tank; second-tank outlet means; and material for further filtering of treated liquid from first tank.

15. A system according to claim 14, further including a second filter chamber mounted in the second tank and having an interior and a periphery, wherein fluid communication is provided between the second-tank inlet means and the second filter chamber's interior through the second filter chamber's periphery, and between the second filter chamber's interior and the second-tank outlet means, and wherein the material for further filtering is located in the interior of the filter chamber.

16. A system for treating a process liquid by removing components from the process liquid, the system comprising: a filter medium; means for filtering the process liquid through the filter medium; means for backwashing filtered liquid back through the filter medium while spinning the filter medium at a first rotational speed so as to remove a first component from the filter medium; and means for spinning the filter medium at a second rotational speed, greater than the first rotational speed, so as to remove a second component.

17. A system according to claim 16, further including: a first outlet for receiving filtered liquid from filter medium; a second outlet for receiving backwashed liquid and the first and second components; a second filter for filtering the backwashed liquid; and means for directing the first component from the second outlet valve through a second filter and directing the second component from the outlet valve away from the second filter.

18. A system according to claim 17, wherein the first component is a suspended solid contaminant and the second component is a liquid contaminant, and wherein the second filter filters the suspended solid contaminant from the backwashed liquid.

19. A method for treating a process liquid by removing components from the process liquid, the method comprising: providing a filter medium; filtering the process liquid through the filter medium; backwashing filtered liquid back through the filter medium while spinning the filter medium at a first rotational speed so as to remove a first component from the filter medium; and spinning the filter medium at a second rotational speed, greater than the first rotational speed, so as to remove a second component.

20. A method according to claim 19, further including the steps of: providing a first outlet for receiving filtered liquid from filter medium; providing a second outlet for receiving backwashed liquid and the first and second components; and directing the first component from the second outlet valve through a second filter; and directing the second component from the outlet valve away from the second filter.

21. A method according to claim 20, wherein the first component is a suspended solid contaminant and the second component is a liquid contaminant, and wherein the second filter filters the suspended solid contaminant from the backwashed liquid.

22. A method for treating a process liquid by removing components from the process liquid, the method comprising: holding the process liquid within a tank having an inlet means for untreated process liquid to enter the tank, first outlet means for treated liquid to leave the tank, and second outlet means; passing the process liquid from the inlet means, through a filter chamber rotatably mounted in the tank and containing a porous filter medium to the tank's first outlet means; controlling the first and second outlet means such that during normal filtering mode, the first outlet means is open, the second outlet means is closed, and treated liquid flows out of the tank through the second outlet means; regenerating the filter medium periodically by spinning the filter chamber at one rotational speed, backwashing treated liquid from the open first outlet means, back through the filter medium from the interior to the exterior of the filter chamber, and directing the resultant liquid component to the second outlet means; and further regenerating the filter medium by closing the first outlet means, spinning the filter chamber at an increased rotational speed such that liquids absorbed in the filter medium are released, and directing the released component to the second outlet means.