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Title:
METHOD AND APPARATUS FOR PREVENTING BYPASS IN A MOVING BED REACTOR
Document Type and Number:
WIPO Patent Application WO/2019/040561
Kind Code:
A1
Abstract:
A method of operating a moving bed reactor includes introducing feed water to be treated into an internal volume of a moving bed reactor, directing the water to be treated through a moving bed of treatment media within the internal volume of the moving bed reactor to form treated water, ejecting treatment media from an eject zone in a lower portion of the moving bed reactor up through a riser tube disposed within the internal volume of the moving bed reactor, and modulating a flow of motive water into the internal volume of the moving bed reactor to include pulses of increased flow of motive water, the pulses of increased flow of motive being sufficient to prevent feed water from bypassing the treatment media and entering the riser tube from a lower end of the riser tube.

Inventors:
DUKES SIMON P (US)
WILLIAM LANE (US)
Application Number:
PCT/US2018/047427
Publication Date:
February 28, 2019
Filing Date:
August 22, 2018
Export Citation:
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Assignee:
EVOQUA WATER TECH LLC (US)
International Classes:
B01D15/18; C07C67/08; C07C67/56
Domestic Patent References:
WO2015066417A12015-05-07
Foreign References:
US20160039724A12016-02-11
US4102776A1978-07-25
US4538636A1985-09-03
Attorney, Agent or Firm:
FREDERICK C., Wilkins (US)
Download PDF:
Claims:
What is claimed is:

CLAIMS 1. A method of operating a moving bed reactor, the method comprising introducing motive water into the moving bed reactor in a pulsed flow pattern, flow pulses of the motive water being sufficient to prevent feed water undergoing treatment in the moving bed reactor from bypassing treatment media within the moving bed reactor. 2. The method of claim 1, further comprising introducing the feed water into a lower portion of the moving bed reactor.

3. The method of claim 2, further comprising introducing the motive water into the moving bed reactor at a position below a location where the feed water is introduced into the moving bed reactor.

4. The method of claim 2, further comprising directing the feed water upward through the treatment media as the treatment media moves downward through the moving bed reactor.

5. The method of claim 4, further comprising ejecting treatment media from an eject zone in a lower portion of the moving bed reactor.

6. The method of claim 5, further comprising ejecting the treatment media up through a riser tube disposed within the moving bed reactor

7. The method of claim 6, wherein preventing the feed water from bypassing the treatment media includes preventing the feed water from entering the riser tube. 8. The method of claim 5, wherein ejecting the treatment media from the eject zone includes periodically providing pulses of air to a lower portion of the moving bed reactor, the pulses of air being of sufficient pressure and volume to eject the treatment media from the eject zone.

9. The method of claim 8, further comprising providing each of the flow pulses of the motive water at a time period at least partially overlapping a time period in which a corresponding pulse of air is provided. 10. The method of claim 9, wherein each air pulse is applied within a time period that a corresponding pulse of motive water is being applied.

11. The method of claim 10, wherein each pulse of motive water is initiated prior to initiation of a corresponding pulse of air.

12. The method of claim 11, wherein each pulse of motive water is terminated after termination of the corresponding pulse of air.

13. The method of claim 10, wherein each pulse of motive water is terminated after termination of a corresponding pulse of air.

14. A system comprising:

a moving bed reactor;

a source of feed water to be treated fluidly connectable to the moving bed reactor; a source of gas connectable to the moving bed reactor;

a source of motive water connectable to the moving bed reactor; and

a controller configured to cause the system to perform the method of any of claims 1-

13. 15. The system of claim 14, further comprising a source of Fe2+ ions fluidly connectable to the moving bed reactor.

16. The system of claim 14, wherein the source of gas is connected to a delivery system configured to deliver the gas through an gas-only inlet of the moving bed reactor.

17. The system of claim 14, wherein the source of motive water is connected to a first sub-system configured to provide the motive water at a steady state baseline flow rate and to a second sub-system configured to supply pulses of motive water at a flow rate greater than the steady state baseline flow rate.

18. The system of claim 17, wherein the source of air is connected to a delivery system configured to deliver the air through a conduit through which the pulses of motive water are provided to the moving bed reactor.

19. The system of claim 14, wherein the source of motive water includes a treated water vessel attached to a conduit configured to receive treated water from the moving bed reactor.

20. A non-transitory computer readable media including instructions which when executed by a controller of a system including a moving bed reactor causes the system to perform the method of any of claims 1-13.

21. A moving bed reactor comprising:

a reactor body;

a gas inlet disposed in a lower portion of the reactor body;

a motive water inlet disposed in a lower portion of the reactor body;

a riser tube disposed within the reactor body and having a lower inlet disposed above the gas inlet;

a moving bed zone defined in the reactor body and configured to retain a fluidized bed of treatment media flowing downward through the moving bed zone;

a feed water introduction conduit configured to introduce feed water into the moving bed zone;

a media ejection zone disposed between the lower inlet of the riser tube and the gas inlet, the moving bed reactor configured such that gas introduced through the gas inlet causes media to be ejected from the media eject zone and up through the riser tube;

a clarification zone disposed within the reactor body above the moving bed zone; and a fluid conduit having an upper end disposed in the clarification zone and a lower end disposed in the media ejection zone, the fluid conduit providing fluid communication between the clarification zone and the media ejection zone.

Description:
METHOD AND APPARATUS FOR PREVENTING BYPASS IN A MOVING BED

REACTOR

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Patent

Application Serial No. 62/549,489, titled "METHOD AND APPARATUS FOR

PREVENTING BYPASS IN A MOVING BED REACTOR", filed August 24, 2017, which is incorporated herein in its entirety for all purposes. BACKGROUND

1. Field of Disclosure

Aspects and embodiments of the present disclosure are directed generally to wastewater treatment systems utilizing moving media beds and methods of operating the same.

2. Discussion of Related Art

Various methods for the treatment of wastewater involve contacting the wastewater to be treated with a catalyzing media. The media facilitates the removal of undesirable components from the wastewater by adsorption and/or by chemical transformation of undesirable soluble components into compounds which are less soluble and thus easier to remove from the wastewater. Media assisted wastewater treatment processes may be performed in reactors having a packed bed and/or a fluidized bed arrangement.

SUMMARY

In accordance with an aspect of the present disclosure, there is provided a method of operating a moving bed reactor. The method comprises introducing motive water into the moving bed reactor in a pulsed flow pattern, flow pulses of the motive water being sufficient to prevent feed water undergoing treatment in the moving bed reactor from bypassing treatment media within the moving bed reactor.

In some embodiments, the method further comprises introducing the feed water into a lower portion of the moving bed reactor.

The method may further comprise introducing the motive water into the moving bed reactor at a position below a location where the feed water is introduced into the moving bed reactor. The method may further comprise directing the feed water upward through the treatment media as the treatment media moves downward through the moving bed reactor.

The method may further comprise ejecting treatment media from an eject zone in a lower portion of the moving bed reactor.

The method may further comprise ejecting the treatment media up through a riser tube disposed within the moving bed reactor

In some embodiments, preventing the feed water from bypassing the treatment media includes preventing the feed water from entering the riser tube.

In some embodiments, ejecting the treatment media from the eject zone includes periodically providing pulses of air to a lower portion of the moving bed reactor, the pulses of air being of sufficient pressure and volume to eject the treatment media from the eject zone.

In some embodiments, the method further comprises providing each of the flow pulses of the motive water at a time period at least partially overlapping a time period in which a corresponding pulse of air is provided.

In some embodiments, each air pulse is applied within a time period that a

corresponding pulse of motive water is being applied.

In some embodiments, each pulse of motive water is initiated prior to initiation of a corresponding pulse of air.

In some embodiments, each pulse of motive water is terminated after termination of the corresponding pulse of air.

In some embodiments, each pulse of motive water is terminated after termination of a corresponding pulse of air.

In accordance with another aspect, there is provided a system comprising a moving bed reactor, a source of feed water to be treated fluidly connectable to the moving bed reactor, a source of gas connectable to the moving bed reactor, a source of motive water connectable to the moving bed reactor, and a controller configured to cause the system to perform any one or more of the methods disclosed herein.

In some embodiments, the system further comprises a source of Fe 2+ ions fluidly connectable to the moving bed reactor.

In some embodiments, the source of gas is connected to a delivery system configured to deliver the gas through an gas-only inlet of the moving bed reactor.

In some embodiments, the source of motive water is connected to a first sub-system configured to provide the motive water at a steady state baseline flow rate and to a second sub-system configured to supply pulses of motive water at a flow rate greater than the steady state baseline flow rate.

In some embodiments, the source of air is connected to a delivery system configured to deliver the air through a conduit through which the pulses of motive water are provided to the moving bed reactor.

In some embodiments, the source of motive water includes a treated water vessel attached to a conduit configured to receive treated water from the moving bed reactor.

In accordance with another aspect, there is provided a non-transitory computer readable media including instructions which when executed by a controller of a system including a moving bed reactor causes the system to perform any one or more of the methods disclosed herein.

In accordance with another aspect, there is provided a moving bed reactor. The moving bed reactor comprises a reactor body, a gas inlet disposed in a lower portion of the reactor body, a motive water inlet disposed in a lower portion of the reactor body, a riser tube disposed within the reactor body and having a lower inlet disposed above the gas inlet, a moving bed zone defined in the reactor body and configured to retain a fluidized bed of treatment media flowing downward through the moving bed zone, a feed water introduction conduit configured to introduce feed water into the moving bed zone, a media ejection zone disposed between the lower inlet of the riser tube and the gas inlet, the moving bed reactor configured such that gas introduced through the gas inlet causes media to be ejected from the media eject zone and up through the riser tube, a clarification zone disposed within the reactor body above the moving bed zone, and a fluid conduit having an upper end disposed in the clarification zone and a lower end disposed in the media ejection zone, the fluid conduit providing fluid communication between the clarification zone and the media ejection zone.

BRIEF DESCRIPTION OF DRAWINGS

Various aspects of at least one embodiment are discussed below with reference to the accompanying figures, which are not intended to be drawn to scale. The figures are included to provide an illustration and a further understanding of the various aspects and embodiments, and are incorporated in and constitute a part of this specification, but are not intended as a definition of the limits of any particular embodiment. The drawings, together with the remainder of the specification, serve to explain principles and operations of the described and claimed aspects and embodiments. In the figures, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every figure. In the figures: :

FIG. 1 is a diagram of an embodiment of a fluidized bed reactor system;

FIG. 2 is a diagram of an embodiment of a moving bed reactor system;

FIG. 3 is a diagram of an embodiment of a moving bed reactor;

FIG. 4 is an enlarged view of a lower portion of the moving bed reactor of FIG. 3.

FIG. 5 A illustrates a pattern of air flow and motive water flow that may be utilized in the moving bed reactor of FIG. 3;

FIG. 5B illustrates another pattern of air flow and motive water flow that may be utilized in the moving bed reactor of FIG. 3;

FIG. 5C illustrates another pattern of air flow and motive water flow that may be utilized in the moving bed reactor of FIG. 3;

FIG. 5D illustrates another pattern of air flow and motive water flow that may be utilized in the moving bed reactor of FIG. 3;

FIG. 6 illustrates a system including the moving bed reactor of FIG. 3;

FIG. 7 is a diagram of another embodiment of a moving bed reactor;

FIG. 8A illustrates results of a test of operating a moving bed reactor with a constant flow of motive water;

FIG. 8B illustrates results of a test of operating a moving bed reactor with a medium flow pulse of motive water; and

FIG. 8C illustrates results of a test of operating a moving bed reactor with a high flow pulse of motive water.

DETAILED DESCRIPTION

Aspects and embodiments disclosed herein are not limited to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. Aspects and embodiments disclosed herein are capable of other embodiments and of being practiced or of being carried out in various ways.

In accordance with one or more embodiments, water may be treated with activated iron. An activated iron water treatment process may utilize a media, for example, zero valent iron in combination with a source or ferrous ions, for example, ferrous chloride to reduce a concentration of heavy metals and/or oxyanions in influent water to be treated. It has been found that the efficiency of a water treatment process using zero valent iron increases as the size of the particles of the zero valent iron decreases, however, as the size of the particles decrease, the media becomes more subject to packing into dense agglomerates or to fusing, thus increasing resistance of flow of water to be treated through the media and/or making less media surface area available for contact with the water. The media may tend to fuse if it is not mobile and moving. As the particle size goes down the fluid resistance of the bed increases, making it less likely that the fluid will move through the bed. In a packed bed reactor, the media is compressed within a reactor that provides contact between the media with the liquid to be treated. Either a packed column or a radial flow device can be used in a packed bed arrangement to treat and remove contaminants, for example, selenium, mercury, and thallium. When activated iron media is used in a packed bed configuration, however, the media can fuse together. Fusing of the media may cause a blockage of liquid flow and reduce the efficiency of the treatment process.

As the media size decreases, it becomes less practical to use the media in a traditional packed bed arrangement. An activated iron water treatment process may be more effectively performed in, for example, a moving packed bed reactor or a fluidized media bed reactor than in a packed bed reactor in accordance with various embodiments. As the term is used herein, a "moving packed bed reactor" is a reactor having a packed bed, for example, a constrained or unconstrained pile, of catalyzing media wherein the catalyzing media in the bed is moved over time from one portion of the bed to another portion of the bed, for example, from a bottom portion of the media bed to a top portion of the media bed or from a top portion of the media bed to a bottom portion of the media bed. The movement of the media helps to keep the media from fusing, which as discussed above may be problematic in previously known systems utilizing media such as ZVI with small particle sizes. A moving packed bed reactor may also be referred to as any one or more of a "moving bed" reactor, a "progressive bed" reactor, a "dynamic bed" or "dynamic column" reactor, a "rolling bed" reactor, a "rapid bed" reactor, a "travelling bed" reactor, a "counter current bed" reactor, a "fluidic bed" reactor, an "active bed" reactor, or a "migrating bed" reactor.

During operation of a fluidized bed reactor or a moving packed bed reactor, some of the activated iron media can be lost due to the turbulence of liquid in the reactor, for example, turbulence due to stirring of a fluidized bed reactor or from movement of the media bed in a moving packed bed reactor. Some aspects and embodiments disclosed herein facilitate recovery of media, for example, activated iron media that might otherwise be lost, and return of the recovered media to a reactor from which the media might otherwise have escaped. During the media recovery process, media which is still in an "active" state may be preferentially recovered as compared to media which has become spent or non-active. In use, a fluidized bed reactor may be continuously or periodically stirred to increase contact between the media and the influent water undergoing treatment. In a fluidized bed reactor, turbulence within the reactor may cause the media to be constantly suspended. This can improve the reaction kinetics by increasing velocity and contaminant interaction within the reactor so that it is possible to rapidly treat and remove contaminants, for example, selenium, mercury, and thallium. Stirring of the fluidized bed may also help prevent the media from fusing together.

In some embodiments, media comprising zero-valent iron (hereinafter Fe(0) or "ZVI") may be provided as small particles or as a powder. In some embodiments, the ZVI powder may have an average particle size of less than about 100 μπι, for example, less than about 90 μπι or less than about 45 μιη. The ZVI media particles may, in some embodiments, be coated to enhance the contaminant removal efficiency of the media. As used herein, the term "coated" may include "having an outer layer at least partially covered with," or "having an outer layer chemically or electrochemically converted to include." In some embodiments, it has been found beneficial to coat the ZVI particles with an iron-containing material, for example, an iron oxide. The ZVI media particles may, in some embodiments, be coated with a layer of magnetite.

In some embodiments a layer of magnetite (Fe 3 0 4 ) is coated on to the ZVI particles by chemically or electrochemically converting the outer layer of the ZVI particles as a conditioning step to maintain the activity of the ZVI during the process of treating wastewater. The removal of contaminants, for example, selenium from wastewater may include the reduction of the high oxidation state of the selenium (+6, +4, etc.) to insoluble elemental selenium by the ZVI. The elemental selenium (or other contaminant) may then be adsorbed to the catalytic media such as ZVI media. The reduction of selenium and other contaminant elements may involve electron transfer from the ZVI to the target element. Without being bound to a particular theory, an example of a reduction reaction of, for example, selenium may occur according to the following reaction:

Se0 4 2" + 2Fe(0) + Fe 2+ 4Se(0) + Fe 3 0 4

Aspects and embodiments disclosed herein may also be useful in removing other components, for example, one or more of silica, aluminum, arsenic, cadmium, chromium, copper, lead, mercury, molybdenum, nickel, thallium, and zinc from wastewater. Over time, the conversion of the ZVI to iron oxides and/or the accumulation of contaminants adsorbed on the surface of the media particles may render the media less effective at removing contaminants from wastewater than fresh media. Media which has become less effective or ineffective for removing contaminants from wastewater may be referred to herein as "spent" or "inactive" media. In some embodiments, the concentration of one or more contaminants in treated water exiting a fluidized bed reactor may be monitored and when this concentration exceeds a desired level, the media in the fluidized bed reactor may be replaced with fresh media. Additionally or alternatively, a fluidized bed reactor may be operated in a "feed and bleed" mode where spent media is removed from the fluidized bed reactor as fresh media is added, allowing the fluidized bed reactor to operate for extended periods of time without being taken out of operation to replace the media. Similar methods of monitoring for breakthrough of contaminants in treated water and of replacement of media, ether as a complete replacement of media or a "feed and bleed" mode of media replenishment may also be applied to moving packed bed reactors as disclosed herein.

The magnetite layer is coated on the ZVI particles to facilitate the electron transfer from the ZVI to the target contaminant element(s). Magnetite, with a small band gap between the valence and the conductance band, is a good electron carrier and therefore facilitates the reduction of the target element by electron transfer from ZVI to the

contaminant(s). The magnetite layer coated on the ZVI may also passivate the ZVI and facilitate prevention of oxidation of the ZVI. The magnetite coating may in some

embodiments be very thin, for example, in a range of from about a monolayer to about a micron in thickness.

In some embodiments where ZVI is used as a contaminant removal media, wastewater to be treated may be dosed with chemicals to increase a concentration of Fe 2+ ions in the wastewater prior to, or during contact of the wastewater with the ZVI media. The Fe 2+ ions may facilitate maintaining the ZVI media in an active magnetite state and prevent substantial oxidation of the ZVI media to inactive oxides. Without being bound to any particular theory, an example of a reaction between the Fe 2+ and the ZVI may include the following reaction:

2y-FeOOH + Fe 2+ Fe 3 0 4 + 2H +

The Fe 2+ ions may be introduced in the form of FeCb or FeS0 4 stock solutions at a set flow rate to maintain the concentration of Fe 2+ ions in the wastewater coming into contact with the ZVI media in a range of, for example, between about 5 mg/L to about 200 mg/L. In some non-limiting embodiments, the range may be between about 5 mg/L to about 50 mg/L. In some embodiments where the wastewater is contaminated with Ni which is to be removed, lower Fe 2+ dosages may be utilized, for example, dosages sufficient to maintain the concentration of Fe 2+ ions in the wastewater coming into contact with the ZVI media in a range of, for example, between about 0 mg/L to about 5 mg/L. The desired concentration of Fe 2+ may be dependent upon the concentration and type of contaminants in the wastewater which are desired to be removed. If more than a desired amount of Fe 2+ , for example, more than is needed to reduce a desired amount of the contaminant ions and maintain the ZVI in an active state, is added to the wastewater to be treated excess Fe 2+ in the wastewater, from dosage as well from in situ generation, will exit the media bed. In some embodiments the effluent of a fluidized bed reactor including the ZVI media may be monitored for the soluble iron levels and the dosage of Fe 2+ may be adjusted until the concentration of soluble iron in the effluent drops below a desired threshold level.

In one embodiment, the process is operated as a fluidized bed reactor using mixers and riser tubes with continuous or intermittent addition of ferrous ion. During operation some of the media may exit with the overflow (also referred to herein as "effluent") and may be removed by downstream aeration or filtration. In embodiments in which the active media is magnetic, a magnetic separation such as a magnetic-drum may be used to recover the active media and return it to the reactor.

FIG. 1 illustrates a diagram of a fluidized bed reactor system 100. The system 100 includes a fluidized bed reactor 110. In some embodiments, the fluidized bed reactor may include between about 50 g/L and about 400 g/L of media, for example, ZVI media. In at least some embodiments, the reactor may include between about 100 g/L and about 200 g/L of media. Wastewater is supplied to the fluidized bed reactor 110 through a first pump 1 12. Other reagents, for example, Fe 2+ and/or a pH adjustment agent, for example, HCl may be supplied to the fluidized bed reactor through second and third pumps 114, 116, respectively. Media, for example, ZVI media, may be supplied from a source of media 145. As described above, the Fe 2+ may facilitate maintaining ZVI media 120 in the fluidized bed reactor 110 in an active magnetite state and prevent substantial oxidation of the ZVI media to inactive oxides. The HCl or other reagent may be used to maintain the pH of fluid in the fluidized bed reactor 110 at a level which facilitates the reduction of selenium compounds such as selenite and selenate into elemental selenium. In some non-limiting embodiments, the pH level in the fluidized bed reactor may be maintained at a level of, for example, between about 2.2 and about 2.4. In at least some embodiments, the pH level of the reactor may be increased or decreased.

A stirrer or mixer 130 in a flow conduit 135 of the fluidized bed reactor 110 may circulate liquid through the fluidized bed reactor 110 to facilitate mixing and contact of contaminants in the wastewater undergoing treatment with the media 120 in the fluidized bed reactor 110. The stirrer 130 also facilities maintaining the media 120 suspended in fluid in the fluidized bed reactor 110, for example, in a fluidized zone 140 of the fluidized bed reactor 110.

An oxygen containing gas, for example, air may be provided from a source of air, for example, a compressor, blower, or other device capable of pressurizing air into the fluidized bed reactor 110 into a portion of the flow conduit 135. Oxygen in the air may facilitate oxidation of selenocyanate in the wastewater undergoing treatment into selenite and/or selenate which is then reduced into elemental selenium when contacted with the ZVI media 120.

Suspended solids in the wastewater undergoing treatment are removed from the fluidized bed reactor 110 in an internal settling zone 150 and then transferred to an aeration basin 155 supplied with air from a source of air 160, where the solids may be aerobically treated in a biological treatment process. In some embodiments, a chemical process may occur in the aeration basin 155 in which soluble iron is converted to an iron oxide or an iron hydroxide which may be settled. Fluid in the aeration basin 155 may be pH adjusted by the addition of a base, for example, NaOH from a source of NaOH 165. Mixed liquor generated in the aeration basin undergoes solids/liquid separation in a settling tank or clarifier 170. A low solids effluent from the settling tank or clarifier 170 is discharged as treated water 180 after optionally passing through a final filter, for example, a sand filtration bed 175. High solids sludge 185 may be returned from the settling tank or clarifier 170 to the fluidized bed reactor 110 for use in capturing additional suspended or dissolved solids from wastewater undergoing treatment in the fluidized bed reactor 1 10.

In some embodiments, a media recovery mechanism is located between an outlet of the fluidized bed reactor 110 and an inlet of the aeration basin 155. The media recovery mechanism may recover media from the fluid stream flowing from the fluidized bed reactor 110 to the aeration basin 155, so the media may be returned to the fluidized bed reactor 110. In some embodiments, between about 10% and about 90%, for example, between about 20% and about 80% of active media leaving the fluidized bed reactor 110 may be recovered by the media recovery mechanism. The media recovery mechanism may include any mechanism capable of recovering or separating media from the fluid from the fluidized bed reactor.

Media recovery systems are disclosed in, for example, PCT application Publication No. WO 2015/066417, which is incorporated herein by reference in its entirety for all purposes.

In some embodiments, a wastewater treatment process is operated utilizing a moving bed reactor including mixers and riser tubes (also referred to as a draft tubes) with continuous or intermittent addition of ferrous ions. The riser tube or draft tube provides a pathway to remove media such as ZVI media from the bottom of the moving media bed, fluidize the media, and then place the media at the top or inlet side of the moving media bed. In some embodiments, a ratio of ZVI media to liquid of about 1 : 1 or more may be utilized in the moving bed reactor. In this way, the media is either continuously or intermittently moved to prevent fusing. In some embodiments, the media may travel from the top of a media bed to the bottom of a media bed and back to the top of a media bed over a course of, for example, less than a week, or between about one day and three days. Effluent quality and its ionic matrix may be some parameters used to determine an amount of time used to turn over the media bed. If contamination concentration increases in the effluent, it may indicate that shorter turnover time is desirable.

In at least some embodiments, a moving bed reactor may exhibit substantially zero pressure rise over at least a ten day period. Pressure rise may be dependent on various factors including the ionic matrix of the wastewater, with higher salinities generally being linked to higher pressure rise. In some embodiments, a moving bed reactor may exhibit a lower residence time for wastewater undergoing treatment than a fluidized bed reactor, for example, a reduction in residence time by about a factor of six.

FIG. 2 illustrates an embodiment of a moving bed reactor, illustrated generally at 200, with a subsystem comprising a central riser or draft tube to move media from proximate the bottom 205 of the reactor to proximate the top 210. Reactor 200 has a riser 215 located generally in the center of the reactor vessel 220. Influent feed water 225 is treated in the media 230 on the outside 235 of the riser 215 and exits the reactor as treated effluent 240. Media enters the riser tube 215 at the bottom 245 of the riser tube 215 proximate the bottom 205 of the reactor 200. Media 230 within 250 the riser tube is moved in an upward direction. The media 230 inside 250 the riser tube 215 is fluidized and transported up the riser tube, for example by air lift. Media 230 is then spilled over the top 255 of the riser tube 215 and falls on the top of the moving bed on the outside 235 of the riser tube. Media 230 will move down the bed under gravity to fill the void left by the ejected media, causing motion in the bed which will avoid the static relationship of media particles which may lead to the media particles fusing.

A source of gas, for example, air can be used in a draft tube device to move the activated iron media from the bottom or effluent side of the reactor to the top or influent side of the reactor. In FIG. 2, a source of gas 260 positioned below the riser tube 215 directs gas into the center portion 250 of the riser tube 215. The gas may comprise compressed air. In some processes involving, for example, treatment of contaminated water from oil and gas extraction operations, the gas may be natural gas. This disclosure is not limited by the type of gas used in a gas driven riser tube arrangement.

Another example of a moving bed reactor is illustrated in FIGS. 3 and 4, indicated generally at 300. FIG. 4 is an enlarged view of a lower portion of the moving bed reactor 300. In the moving bed reactor 300, the media (for example, ZVI media) is circulated from the bottom to the top of the reactor 300 utilizing air injected into a lower end of the reactor 300 to provide the motive force for circulating the media upward through a central riser tube 315. Referring to FIG. 3, in the moving bed zone 310 feed water moves upward in region 335 surrounding the riser tube 315 and a feed water introduction conduit 320 toward a free surface within the body 305 of the reactor 300 at a low velocity. The media forming the moving bed moves downward through the region 335. The feed water introduction flow rate and bed movement rate are selected such that the feed water is driven upward through the reactor 300.

The active zone for treatment of the feed water is the moving bed zone 310. Feed water to be treated is introduced into the reactor 300 through feed water introduction conduit 320. The feed water exits the feed water introduction conduit 320 and is distributed radially out of the distribution bell 340 and then upwards through the moving media bed (omitted from FIG. 3 for clarity) in the moving bed zone 310 as it is treated. Motive water is pumped in the bottom of the reactor through motive water introduction port 355 to keep the media fluidized at the base of the lower cone 360 and to ensure that the feed water moves upward through the media bed. At the same time that the feed water is moving upward through the moving bed zone 310, the media moves downwards under the force of gravity through the moving bed zone 310. The fall of the media is controlled by the angle of repose of the media, the natural angle that it will settle to. Media is ejected from an eject zone 345 at a lower end of the body 305 of the reactor 300, along with some entrained water, by air introduced through a lower air introduction port 350. The air introduced through the lower air introduction port 350 circulates the media up through the riser tube 315 and keeps the media well mixed. The air is introduced through the lower air introduction port 350 in periodic pulses. Rising bubbles entrain water and media which is then transported up the central riser tube 315. The air flow is provided in pulses to result in slugs of water moving up the riser tube 315 to maximize the entrainment of the media. The motive water introduced into the reactor 300 keeps the media in a fluidized state and eases the movement of the media both down into the eject zone 345, and out of it. The media is released from the riser tube 315 into the clarification zone 375, where it settles out under gravity and is deposited onto the top of the moving media bed. As media is removed from the bottom of the eject zone 345, more media flows down to replenish it. In this way the media bed is slowly turned over.

If the instantaneous flow of water up the riser tube 315 is greater than the flow of motive water into the reactor 300, a reduction in local pressure in zone A (FIG. 4) in the eject zone 345 is caused. This movement induced pressure decrease may induce a down flow of water from the media bed, that may cause feed water to short-circuit the media bed and result in insufficiently treated water being ejected up the riser tube 315, from where it may exit the reactor 300 as product water through product water exit conduit 365, degrading the performance of the system.

Accordingly, in some embodiments, the motive water flow rate is adjusted to compensate for the volume of water pulled through the riser tube 315 by the air lift effect of the rising bubbles. To minimize the pressure drop and reduce or eliminate feed water bypass that may be caused by the air injection, additional motive water is provided through the motive water introduction port 355 in pulses synchronized with the pulses of air utilized for the media air lift. The additional motive water injection replaces the volume of the air injection and water ejected up the riser tube 315, maintaining a positive pressure in the zone A in the eject zone 345 and preventing backflow and bypass of feed water into the riser tube 315, forcing all feed water to flow through the media bed for treatment. In other

embodiments, the additional pulses of motive water may be introduced through a separate port other than the motive water introduction port 355.

One consequence of the introduction of the motive water is that the amount of motive water introduced has a significant effect to the total flow leaving the reactor 300 and moving on to other downstream processes. This has an effect on the size of the downstream equipment. Proper sequencing of motive water and air flow may permit the use of an air lift in the moving bed reactor, while minimizing the effect of that water on the size of the downstream equipment. In addition to the feed water introduction conduit 320, motive water introduction port 355, and air introduction port 350, the reactor 300 may also be provided with inlets to receive a source of Fe 2+ and/or a pH adjustment agent and/or replacement treatment media as described with reference to the system of FIG. 1 above. The reactor 300 may also include an inlet for receiving media recovered from treated water exiting the reactor, as described in PCT application Publication No. WO 2015/066417.

FIGS. 5A-5D show the examples of transient flow profiles for the feed and motive water and air injection. The feed water is held constant for the duration of the system operation. The motive water has two components, a baseline flow and periodic injections at a higher flow rate than the baseline flow. The baseline flow is tuned to maintain the desired residence time of the feed water while the high flow injections are tuned to compensate for the air injection. The air injection occurs at a different amplitude and phase compared to the motive water, and it is tuned to circulate the ZVI media at a given rate. In some

embodiments, each air injection pulse is correlated with a corresponding high flow motive water pulse. The times at which each air injection pulse and its corresponding high flow motive water pulse occur may at least partially overlap. FIG. 5A illustrates a sequence of air and motive water flow patterns in which the air flow pulses are symmetric, with an increased flow of motive water (a high flow motive water pulse) leading and lagging each air pulse in time. FIG. 5B illustrates a sequence of air and motive water flow patterns in which the air flow pulses are asymmetric with increased flow of motive water leading the air pulses and the air pulses terminating at the same times as the pulses of increased flow of motive water terminate. FIG. 5C illustrates a sequence of air and motive water flow patterns in which the air flow pulses are asymmetric with increased flow of motive water and air pulses beginning together at the same times but with increased flow of motive water continuing for a period of time after the air pulses terminate. FIG. 5D illustrates a sequence of air and motive water flow patterns in which the air flow pulses are asymmetric with increased flow of motive water slightly leading the air pulses and the air pulses terminating at the same times as the pulses of increased flow of motive water terminate. FIG. 5D also illustrates non-limiting examples of flow rates for the air and motive water. In each of FIGS. 5A-5D, each air pulse occurs within a time that a corresponding high flow motive water pulse is being applied. In other embodiments one of the air pulses or the high flow motive water pulses at least partially during a time period in which the corresponding other of the air pulses or the high flow motive water pulses are not being applied. In some embodiments, individual pulses of air and/or motive water may have durations of from about two to three seconds or more with the time between adjacent pulses being between about five and ten seconds or more.

As illustrated in FIG. 6, in some embodiments product water produced in the reactor may be utilized as the motive water. Air may be introduced either through an air-only inlet port 350 at a lower end of the reactor 300, or additionally or alternatively, may be introduced along with motive water through a common conduit through the motive water introduction port 355 into the reactor 300. The baseline motive water flow may be provided by a first pump, for example, P2 in FIG. 6 while the periodic high flow motive water pulses are provided via a separate second pump, for example, P3 in FIG. 6. In other embodiments, instead of or in addition to using pumps P2, P3 to control the flow of motive water, a pressurized source of motive water may be provided and flow of the motive water may be modulated through control valves, or a combination of one or more flow control devices and actuated valves.

As illustrated in FIG. 6, a system 600 including the moving bed reactor 300 may include a number of ancillary systems and apparatus to support operation of the moving bed reactor 300. Feed water to be treated in the moving bed reactor may be stored in and provided from a feed water tank, which may include a connection to an external source of feed water. The feed water tank may include a level float LF and a low level sensor LSL to provide an indication of a level of feed water in the tank so that more feed water may be introduced when the tank is at least partially empty but not so much feed water is provided to overflow the tank. The feed water may be introduced to the moving bed reactor though a delivery system including a pump PI and one or more valves, for example a ball valve V2, a needle valve V3, and a non-return valve RV1. It is to be understood that these types of valves are exemplary only and in other embodiments, any other system of pump(s) and valve(s) appropriate for delivering the feed water to the moving bed reactor may be used. For example, V2 may be any suitable form of isolation valve or shutoff valve and V3 may be any suitable form of flow control valve or modulating valve. The same holds true for other valves referred to exemplarily as ball valves or needle valves herein. In some embodiments a flow indicator FI1 may be used to monitor the flow of feed water into he moving bed reactor 300.

In some embodiments, a dosing tank may be provided to supply reagents, for example, a source of Fe 2+ ions (e.g., a source of FeCb) and/or pH adjustment agent, for example, an acid to the moving bed reactor 300. A dosing pump DP and a non-return valve RV5 may be utilized to supply the reagent(s) to the moving bed reactor. A level sensor LSL3 may be provided to monitor the level of reagents in the dosing tank. The reagent(s) from the dosing tank may be supplied to the moving bed reactor 300 through a common conduit as the feed water, as illustrated in FIG. 6, or in other embodiments, though a separate conduit.

Product water exiting the moving bed reactor 300 through product water exit conduit

365 may be delivered to a product water tank for storage, optionally after passing though an anti-syphon device 605 to smooth the flow rater out of the reactor and which may vent any air entrained in the product water to atmosphere. The product water tank may include a low level sensor LSL2 that may provide an indication that additional product water is needed and a drain through which product water overflowing the product water tank may be removed.

Product water in the product water tank may be utilized as motive water for the moving bed reactor 300. The motive water may be delivered to the motive water introduction port 355 into the reactor 300 through a first motive water delivery system including, for example, a ball valve V4 a pump P2 a needle valve V5, a non-return valve RV2 and a flow indicator FI2. The motive water supplied via the first motive water delivery system may be supplied at a steady state flow rate or at a pulsed flow rate. Motive water may also or alternatively be delivered to the motive water introduction port 355 into the reactor 300 through a second motive water delivery system including, for example, a ball valve V6 a pump P3 a needle valve V7, a non-return valve NRV3 and a flow indicator FI3. In some embodiments, one of the first motive water delivery system and the second motive water delivery system may deliver motive water to the reactor 300 at a steady state flow rate while the other of the first motive water delivery system and the second motive water delivery system may deliver motive water to the reactor 300 at a pulsed flow rate. It is to be appreciated that in different embodiments different components other than the pumps, valves, and flow indicators illustrated in FIG. 6 may be utilized to supply motive water to the moving bed reactor 300. Additionally, in some embodiments, the motive water is supplied for a source other than a product water tank and may not include product water from the moving bed reactor 300.

A supply of gas, for example, air (the AIR SUPPLY illustrated in FIG. 6) may provide air to the moving bed reactor 300. Air may be supplied from the air supply to the lower air introduction port 350 of the moving bed reactor 300 from the air supply via a series of valves, for example, ball valve V8, needle valve VI 0, control valve V2, and non-return valve RV4. In other embodiments, different types or numbers of valves may be utilized in the air supply system. A pressure indicator PI2 may be disposed on a conduit of the air supply system to provide feedback regarding operation of the air supply.

In some embodiments, P3 may be an air operated diaphragm pump in this case. A second branch of the air supply system including needle valve V9, pressure indicator PI1 and control valve CV1 may be used to drive and control pump P3. In other embodiments, a pressurized water line and a control valve may be substituted for the second branch of the air supply system and pump P3. It is to be appreciated that in other embodiments, the air supply system may be configured differently and include different components than those illustrated in FIG. 6.

A programmable logic controller (PLC) is used to control the reactor and ancillary sub-systems, for example, pumps and valves for introduction of feed water, motive water, air, chemical additives, media, etc. The PLC connects to, for example, the motive pump and a solenoid valve controlling the air flow as illustrated in FIG. 6. The PLC allows fine-tuning of the amplitudes, periods, and phase-shifts of the injections of air and motive water. This gives aspects and embodiments disclosed herein the versatility of being applied to different systems. In other embodiments a controller other than a PLC, for example, an ASIC, a general-purpose computer, or one or more timers may be utilized to control the reactor and ancillary sub systems. The controller may include a non-transitory computer readable media, for example, a hard drive, flash memory, EEPROM, or other form of computer readable media that includes instructions that when executed by controller, cause the controller to perform any of the methods disclosed herein.

It is to be appreciated that methods of retrofitting an existing reactor to perform methods as disclosed herein by reprogramming its controller utilizing computer readable instructions included in a non-transitory computer readable medium fall within the scope of this disclosure.

Another embodiment of a moving bed reactor 700 is illustrated in FIG. 7, which is a simplified illustration a lower portion of the reactor 700. As in the reactor illustrated in FIGS. 3 and 4, feed water to be treated is introduced into the reactor 700, for example, through a feed water introduction conduit 320, such as illustrated in FIGS. 3 and 4 (but omitted from FIG. 7). The feed water is distributed into treatment media flowing downward through the moving bed zone 310 via the distribution bell 340 and then upwards through the moving media bed. Treated water exits the media in the moving bed zone and enters the clarification zone 375 from which it may exit the reactor 700 as treated effluent through product water exit conduit 365. Motive water is introduced into a lower portion of the reactor below the moving bed zone 310 through motive water introduction port 355 to keep the media fluidized at the base of the lower cone 360 and to ensure that the feed water moves upward through the media bed. Media is ejected from an eject zone 345 at a lower end of the body 305 of the reactor 300, along with some entrained water, by gas, for example, air introduced through a lower air introduction port 350. The gas introduced through the lower air introduction port 350 circulates the media up through the riser tube 315 and keeps the media well mixed. The air is introduced through the lower air introduction port 350 in periodic pulses. The media ejected from the eject zone 345 exits the top of the riser tube 315 into the clarification zone 375 and circulates downward back through the moving bed zone 310.

Ejection of media and water from the eject zone 345 up through the riser tube 315 is compensated for to prevent a pressure drop in zone A which might otherwise cause feed water to short circuit the media bed by being drawn into the eject zone 345 and up the riser tube 315. A conduit, for example a tube 710, which may run parallel to or be coaxial with the riser tube 315 permits water (represented by the dashed lines in FIG. 7) to be drawn down from the clarification zone 375 into the eject zone 345, relieving any pressure drop that might otherwise be caused by ejection of media and water from the eject zone 345 up through the riser tube 315. In the embodiment of FIG. 7 pulses of motive water may not be required to prevent feed water from bypassing the media bed.

Example:

A moving bed reactor as illustrated in FIGS. 3 and 4 was operated under different conditions of motive water flow: Motive water provided at a constant rate (200 ml/min) with no pulsing; Motive water provided with a medium flow pulse (1100 ml/min); and Motive water provided with a high flow pulse (2400 ml/min). A salt solution was introduced as feed water into the moving bed reactor. Conductivity measurements were taken at a lower portion of the moving bed (a Bed 2 location), an upper portion of the moving bed (a Bed 1 location), and in the eject flow through the riser tube. The measured conductivity (in arbitrary units) at each of the three locations over time is illustrated in the charts of FIGS. 8A-8C. As can be seen, providing the motive water with the medium flow pulse (FIG. 8B) reduced the concentration of salt in the eject flow through the riser tube, as indicated by the measured conductivity, by about 50% as compared to the moving bed reactor operating with a constant motive water flow rate (FIG. 8A). Operating the moving bed reactor with the high flow pulse reduced the concentration of salt in the eject flow through the riser tube to an even greater degree. These results show that operating a moving bed reactor as disclosed herein with a pulsed flow of motive water can significantly reduce bypass of feed water from the media bed, and thus significantly reduce an amount of untreated water that may mix with treated water in the reactor.

The aspects disclosed herein in accordance with the present invention, are not limited in their application to the details of construction and the arrangement of components set forth in the following description or illustrated in the accompanying drawings. For example, it should be appreciated that air and motive water may be delivered to embodiments of the reactors disclosed herein through a common conduit instead of, or addition to through separate inlets. These aspects are capable of assuming other embodiments and of being practiced or of being carried out in various ways. Examples of specific implementations are provided herein for illustrative purposes only and are not intended to be limiting. In particular, acts, components, elements, and features discussed in connection with any one or more embodiments are not intended to be excluded from a similar role in any other embodiments.

Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. Any references to examples, embodiments, components, elements or acts of the systems and methods herein referred to in the singular may also embrace embodiments including a plurality, and any references in plural to any embodiment, component, element or act herein may also embrace embodiments including only a singularity. References in the singular or plural form are not intended to limit the presently disclosed systems or methods, their components, acts, or elements. The use herein of "including," "comprising," "having," "containing," "involving," and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. References to "or" may be construed as inclusive so that any terms described using "or" may indicate any of a single, more than one, and all of the described terms. In addition, in the event of inconsistent usages of terms between this document and documents incorporated herein by reference, the term usage in the incorporated reference is

supplementary to that of this document; for irreconcilable inconsistencies, the term usage in this document controls.

Having thus described several aspects of at least one example, it is to be appreciated that various alterations, modifications, and improvements will readily occur to those skilled in the art. For instance, examples disclosed herein may also be used in other contexts. Such alterations, modifications, and improvements are intended to be part of this disclosure and are intended to be within the scope of the examples discussed herein. Accordingly, the foregoing description and drawings are by way of example only.