Patent Application
20090130742
The invention relates to a vessel and system for the biological regeneration of ion exchange and absorptive media. More specifically, the invention relates to a contacting system for the regeneration of ion exchange and/or absorptive media utilizing biological degradation as the method of regeneration.
In, for example, treatment of drinking water to render it potable, ion exchange and absorptive media are used to remove harmful contaminants. For example, perchlorate found in drinking water is a contaminant know to pose serious health risks. One method of removing contaminants, such as perchlorates, from drinking water is by treating the contaminated water with ion exchange and/or absorptive media. Eventually, in any treatment using ion exchange and absorptive media system, the media becomes exhausted and is no longer effective in removing the harmful contaminants. Thus, there is a need for a system and method for treating contaminated wastewaters to address the regeneration of media.
In one aspect, the invention provides a system for biological regeneration of ion exchange and absorptive media. The system comprises a vessel configured to contain a bed of contaminated media particles and having a first region, a second region and a third region. The first region is configured to receive a biological regenerating fluid for contacting media particles at a first volumetric flowrate. This first volumetric flowrate is sufficient to produce a shear force high enough to reduce bio-film thickness on the media particles, while not so high as to cause significant attrition of the media. The second region is configured to receive a portion of biological regenerating fluid from the first region, wherein the portion of biological regenerating fluid in the second region has a second volumetric flowrate lower than the first volumetric flowrate. The third region configured to receive another portion of biological regenerating fluid from the first region, wherein the another portion of biological regenerating fluid in the third region has a third volumetric flowrate lower than the second volumetric flowrate.
In another aspect, the invention provides a method of biologically regenerating ion exchange and/or absorptive media. In one step, the method comprises feeding a biological regenerating fluid into a first region of a vessel containing contaminated media particles at a first volumetric flowrate sufficient to produce a shear force high enough to reduce bio-film thickness on the media particles. In another step, the method comprises dividing the biological regenerating fluid from the first region into portions. In yet another step, the invention comprises directing one of the portions of biological regenerating fluid into a second region of the vessel at a second volumetric flowrate lower than the first volumetric flowrate. In further step, the invention comprises directing another one of the portions of biological regenerating fluid into a third region of the vessel at a third volumetric flowrate lower than the second volumetric flowrate.
In an embodiment according to aspects of the invention, the invention provides a system for biological regeneration of ion exchange and absorptive media. According to the embodiment, the invention includes a vessel configured to contain a bed of contaminated media particles. The system further includes a draft tube disposed within the vessel and having an inlet spaced above a bottom of the vessel and an outlet disposed proximate to a top of the bed of media particles, the draft tube configured to receive a biological regenerating fluid for contacting the contaminated media particles. The embodiment also includes a substantially annular region longitudinally disposed at an elevation above the draft tube outlet and below a liquid deflector being disposed above the draft tube outlet, and radially disposed between an outside wall of the draft tube and an inside wall of the vessel, the substantially annular region configured to receive a portion of biological regenerating fluid from the draft tube. Further, the system includes an upper region of the vessel disposed above the deflector and comprising an area defined by a substantially full inside diameter of the vessel, the upper region configured to receive another portion of biological regenerating fluid from the draft tube.
In another embodiment according to aspects of the invention, the invention provides a system for biological regeneration of ion exchange and absorptive media. The system includes a vessel configured to contain a bed of contaminated media particles. The system further includes a central passage disposed within the vessel and having an inlet disposed at a top of the vessel and an outlet disposed at an elevation above and spaced apart from a bottom of the vessel, the central passage configured to receive biological regenerating fluid for contacting the contaminated media particles. The system according to this embodiment also includes a first substantially annular region configured to receive biological regenerating fluid from the central passage, the first substantially annular region longitudinally disposed from a bottom of the vessel to a top of the media bed, and radially disposed between an outside wall of the central passage and an inside wall of the vessel. Further, the system includes a second substantially annular region longitudinally disposed (1) from a top of the media bed to an elevation below first gas deflector disposed in an upper region of the vessel, (2) between an outside wall of the central passage and an inside wall of the vessel, the second substantially annular region configured to receive a portion of biological regenerating fluid from the first substantially annular region. The system according to this embodiment also includes an upper region of the vessel longitudinally disposed above the gas deflector and between the outside wall of the central passage and the inside wall of the vessel. The upper region is configured to receive another portion of biological regenerating fluid from the first substantially annular region.
In yet another embodiment according to aspects of the invention, the invention provides a system for biological regeneration of ion exchange and absorptive media. The system includes a vessel configured to contain a bed of contaminated media particles. The system further includes an outer central passage positioned within the vessel and has an inlet disposed at a top of the vessel and an outlet disposed in an upper region of the vessel. The outer central passage is configured to receive a biological regenerating fluid for contacting the contaminated media particles. The system according to this embodiment also includes a first substantially annular region longitudinally disposed between a bottom region of the vessel and a top of the media bed, and radially disposed between an outer wall of the inner central passage and an inner wall of the vessel. The first substantially annular region is configured to receive a portion of biological regenerating fluid from the outer central passage. Further, the system includes an inner central passage having an inlet at a bottom region of the vessel and an outlet disposed at the top of the vessel, the inner central passage being configured to receive the portion of biological regenerating fluid from the first substantially annular region. The system according to this embodiment also includes a second substantially annular region longitudinally disposed between a top of the media bed and a top of the vessel and radially disposed between the outer wall of the outer central passage, a portion of the inner central passage and the inner wall of the vessel. The second substantially annular region is configured to receive another portion of biological regenerating fluid from the outer central passage.
The invention is best understood from the following detailed description when read in connection with the accompanying drawing. It is emphasized that, according to common practice, the various features of the drawing are not to scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity. Included in the drawing are the following figures:
This invention generally relates to a method for regenerating exhausted media in which one of the steps includes a biological regeneration step. In such a biological regeneration step of the regeneration process it is preferred for the contaminant that is contained within the ion exchange or adsorptive media to diffuse into the bulk liquid phase on the outside of the particle in order for the biological degradation to occur. The bioactivity in the bulk liquid phase continually destroys the contaminant and therefore the concentration of the contaminant in the liquid phase remains very low. Diffusion of the contaminant from the interior of the media particle to its surface and finally into the bulk liquid phase is motivated by a concentration gradient. As contaminants are removed from the media a counter flow of water and dissolved minerals and ions diffuses into the media particles in order to replace the void space left by the contaminants and, in the case of ionic constituents, to maintain electrical neutrality. It is preferred in this process to improve the rate of diffusion and to promote complete regeneration of all the media particles.
The regeneration process typically causes gases to evolve. For example, carbon dioxide and nitrogen, among other gases, may be generated due to the bio-conversion from dissolved organic constituents and/or nitrates. The gas will often evolve as a fine bubble on the surface of the media particle.
Further, biomass will tend to grow within the contacting system as a film on the surface of the media particle. This is because of the tendency of biomass to stick to surfaces and because constituents diffusing out of the media particle are a nutrient source for the microorganisms. The combination of gas bubbles and biomass growth on the surface of the media particles increases the particle buoyancy. In a contacting system that is flowing and relies on gravity as the means of separation of the media particles from the bulk fluid (such as in a biological fluidized bed reactor) the increased buoyancy of the particle often reduces the efficiency of the gravity separation and causes loss of media from the vessel. Use of a positive means of retaining the media, such as a screen or filter, though an optional alternative, can result in pluggage with biomass or significant maintenance.
Generally, the present invention provides a system and process for the biological regeneration of ion exchange and/or absorptive media, such as ion exchange resin, granular activated carbon, activated alumina, synthetic adsorbents and zeolites. In one aspect, the invention provides a system for biological regeneration of ion exchange and absorptive media comprising a vessel configured to contain a bed of contaminated media particles. As represented by the block diagram in
One of the portions of the flow is defined as being equal to the induced flow, Fi, and enters the second region, Zone B, as illustrated in
The third region of the vessel, Zone C, is configured to receive another portion of biological regenerating fluid from the first region. This portion of biological regenerating fluid introduced into the third region has a third volumetric flowrate which is lower than the second volumetric flowrate. This flow into Zone C is equal to the motive flow, Fm, as shown in
In order to achieve a shear force high enough to reduce bio-film thickness on the media, but not enough shear to cause attrition of the media, it is expected that the induced flow would be equal to the motive flow or as high as four times the motive flow. The shear force may be adjusted, for example, by varying the pressure of the motive flow, throttling the discharge from pumping device 23 and/or varying the speed of the pumping device 23.
As shown schematically in the flow diagram of
Further details of exemplary embodiments of the invention are now provided, with reference to
The draft tube 102 optionally may be configured to receive the portion of the biological regenerating fluid of the second region (described below) at the inlet 103 for recirculation back into the draft tube 102. Further, the draft tube 102 receives the biological regenerating fluid from a feed device 105, such as a tank mixing eductor (TME), an impeller arrangement or a gas airlift device. Preferably, the feed device 105 is a TME, for example, of the type manufactured by Penberthy, Inc. of Prophetstown, Ill. The feed device 105, as shown in
As shown in
Vessel 100 further includes a third region disposed above the liquid deflector 107. This third region includes an upper region of the vessel 100 which comprises an area defined by a full inside diameter of vessel 100. The third region is configured to receive the second portion of biological regenerating fluid from the draft tube 102. This second portion has a third volumetric flowrate lower than the second volumetric flowrate. The flow in the third region may include a volumetric flowrate equal to the motive flow, Fm, of the fluid.
Optionally, the draft tube 102 is provided with an external baffle arrangement, or skirt, 106, such as that shown in
As shown in the embodiments of
According to the embodiments shown in
In this embodiment of the invention, the second region, Zone B, comprises the substantially annular region between the draft tube 102 and the inner wall of the vessel 100, as shown in
The third region in this embodiment is located above the draft tube 102. The flow in this region is upward and equal to the motive flow, Fm, that is fed by feed device 105. It is believed that the flow rate is approximately one-third of the total flow through the draft tube 102, which is equal to the motive flow, Fm, and the induced flow, Fi. The area of vessel 100 in this third region is based on substantially the full vessel diameter and is the largest cross-sectional passage area that the fluid flows through inside the vessel 100. Thus, the combination of low flow and high area result in a very low velocity in the third region. Additionally, the buoyancy of the media particles is minimized as a result of the very thin biofilm layer or layers resulting from the shear applied in the draft tube 102. Accordingly, the separation of the media 101b from the biological regenerating fluid bio-suspension occurs at a very high efficiency. The bio-suspension exits the vessel 100 via a collection system, such as a collector, 108 that is designed to disengage any remaining media particles 101b and gas bubbles from the stream.
As shown in
As noted above, vessel 100, as shown in
The vessel 100 may be made from corrosion resistant material, such as fiberglass, or the vessel may be made from steel that has been coated with a corrosion resistant material. In certain embodiments, the resin retaining screen 109 may be a metallic screen made from exotic metals, such as MONEL® or duplex alloys.
The vessel 100 can optionally be operated at atmospheric pressure. Additionally, the operating pressure within the vessel 100 may be maintained at a level that prevents, inhibits or reduces gas that is converted from the dissolved liquid phase into a free gas state. As liquid exits the vessel 100, via outlet 121, the pressure may be reduced to atmospheric conditions to liberate the gases that have formed in the contacting (regeneration) vessel 100. Agitation may optionally be used outside of the contacting vessel 100 to further enhance liberation of gases. After the excess gases are removed from the biological regenerating fluid, the fluid may be re-pressurized inside the contacting vessel 100. As it enters the contacting vessel 100, the bio-suspension may thus be maintained in a substantially sub-saturated state, thus allowing the bio-suspension to absorb and accumulate more gas in a dissolved liquid state without evolution of free gas.
In further embodiments according to the first aspect, as shown in
Further, the first region also includes a substantially annular region outside the central passage 202. More specifically, this substantially annular region is longitudinally disposed from a bottom of the vessel 200 to a top of the bed 201a of media particles 201b, and radially disposed between an outside wall of the central passage 202 and an inside wall of the vessel 200. The substantially annular region is configured to receive a portion of biological regenerating fluid from the central passage 202. The flow in this first region includes the total flow of the system, i.e. the motive flow, Fm, plus the induced flow, Fi.
In the second region, the vessel 200 is provided with a second substantially annular region longitudinally disposed from a top of the bed 201a of media particles 201b to an elevation below a first gas deflector 214 being disposed at an elevation in an upper region of the vessel 200, and radially disposed at an elevation between an outside wall of central passage 202 and an inside wall of the vessel 200. The second substantially annular region is configured to receive a first portion of biological regenerating fluid from the first substantially annular space.
As shown in
In these embodiments, the third region of vessel 200 further includes an upper region of the vessel 200, longitudinally disposed above the gas deflector 212 and between an outer wall of the central passage 202 and an inner wall of the vessel 200. The upper region is configured to receive a second portion of biological regenerating fluid from the first substantially annular region. The second portion of the biological regenerating fluid has a third volumetric flowrate lower than the second volumetric flowrate. The flow in this third region is equal to the motive flow, Fm, of the fluid, which is less than the induced flow, Fi. The biological regenerating fluid exits the vessel 200 via outlet 221 for recirculation back to the vessel 200.
In these embodiments, the bed of media particles 201b is fluidized as the biological regenerating exiting from the outlet 204 of central passage 202 flows upward through the bed of media particles 201b, as shown in
The vessel 200 according to these embodiments optionally comprise a frusto-conical shaped bottom, as shown in
The system according to these embodiments as shown, for example, in
In an embodiment of the invention, such as shown in
Optionally, the vessel 200 may further include a lower baffle arrangement 216 in a bottom region of the vessel 200, as shown in
Further, the vessel 200 includes, as shown in
In yet another embodiment, exemplified by
The system as shown in
As shown in
The vessel 300 further includes in the third region, Zone C, a second substantially annular region disposed longitudinally between a top of the bed 301a of media particles 301b and the top of the vessel 300. Each of Zones A, B and C, as they are substantially located in vessel 300, are illustrated in
Further, as shown in
The system according to this embodiment provides a vent 310 configured to release gas evolved as a bio-conversion product between the contaminated media 301b and the biological regenerating fluid. To ensure that gas bubbles and media particles 301b are disengaged from the biological regenerating fluid, the vessel 300 may also be provided with a gas deflector 315 disposed in an upper region of the vessel 300. The gas deflector 315 can include a baffle having a frusto-conical shape with the lower portion directed toward the outer central passage 317 of the vessel 300. Alternatively, the gas deflector may also have a cylinder shaped configuration rather than a substantially frusto-conical shape.
In this embodiment, the vessel configuration allows the bed to be packed and the vessel to operate with a downward flow. The overall vessel volume may be reduced because the media in this embodiment is not expanded.
In another aspect, the invention provides a method of biologically regenerating ion exchange and/or absorptive media. The method includes feeding a biological regenerating fluid into a first region of a vessel containing contaminated media particles. The biological regenerating fluid is fed at a first volumetric flowrate sufficient to produce a shear force high enough to reduce bio-film thickness on the media particles. In a next step, the method includes dividing the biological regenerating fluid from the first region into portions and directing one of the portions of biological regenerating fluid into a second region of the vessel at a second volumetric flowrate lower than the first volumetric flowrate. The method further includes directing another one of the portions of biological regenerating fluid into a third region of the vessel at a third volumetric flowrate lower than the second volumetric flowrate. In embodiments according to this aspect, gases are caused to evolve from the contaminated media that are produced from bio-conversion of the biological regenerating fluid and the contaminated media.
In an embodiment according to this aspect, the method includes directing the portion of the biological regenerating fluid having the second volumetric flowrate downward toward a bottom of the vessel. A further step of this embodiment may comprise directing the second portion of the biological regenerating fluid upward toward a top of the vessel.
In another embodiment according to this aspect, the method optionally comprises the step of recirculating the biological regenerating fluid of the second portion to the first region.
The system and method for regenerating ion exchange and absorptive media according to embodiments of the present invention generally provides the advantage that bio-films on the surface of the media particles are controlled and are maintained in a very thin state due to an optimum application of sheer force on the media particles. This minimizes the resistance to diffusion that would otherwise be caused by the bio-film. Additionally, the overall particle density is not adversely affected and its buoyancy is not increased.
Further, according to exemplary embodiments of this invention, gases are inhibited from forming and are separated from the particles and removed from the bulk fluid flow before they can adversely affect the ability of the particle to be separated from the bulk liquid bio-suspension and reduce regeneration time. This is accomplished by application of an optimum amount of sheer to the particles and by changes in direction of flow within the vessel as the liquid bio-suspension and fluidized media flow through the vessel.
Another advantage of exemplary embodiments of the present invention is that the embodied configurations provide rapid mix zones, with the media placed into circulation causing substantially all particles to be equally exposed to the flowing bio-suspension. Thus, the system according to exemplary embodiments of this invention, has no “dead areas” or areas where media may be trapped and not adequately exposed to the biological regenerating fluid, or bio-suspension. This is preferred because any media that would otherwise be trapped in “dead” or low flow areas would not be fully regenerated and would cause premature leakage in the adsorptive or ion exchange systems into which the regenerated media would subsequently be placed. Thus, it is believed that near complete regeneration of substantially all media with no “dead” or low activity zones is attained.
A still further advantage of exemplary embodiments of the present invention is that its configuration provides very low up-flow velocity of the bio-suspension in the upper regions of the vessel to separate out the media particles. This greatly reduces the chance for media carryover due to free gas bubbles on the media, thus preventing, or at least reducing, media loss.
Although the invention is illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the invention.
