Regenerating mixed media filler with adsorption amendments

Abstract

A process is described to regenerate mixed media beds. The process includes charging a mixed media bed with amendment and contacting the amendment in the mixed media bed with contaminants in a liquid stream until the amendment is spent. The process includes applying backwash liquid flow to the mixed media bed and capturing spent amendment in the backwash liquid flow. The mixed media bed with is recharged with fresh amendment to remove additional contaminants from a liquid stream.

Description

Docket No. 1710.00077WGREGENERATING MIXED MEDIA FILLER WITH ADSORPTION AMENDMENTSCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 722,279, filed November 1 , 2024, the disclosure of which is incorporated herein by reference in its entirety.TECHNICAL FIELD

[0002] This disclosure relates generally to contaminant removal from waste streams, and more particularly to methods for regenerating mixed media bed filler with powdered adsorption amendments.BACKGROUND

[0003] Mixed media beds are used in various industries to filter impurities and contaminants from liquid streams. Mixed media beds typically consist of two or more layers of different types of materials. The materials may differ in parameters such as particle size, density, morphology, or other differences. The materials used as media are often granules, particles, or powders. In operation, liquids flow through the mixed media bed, and particulates or other contaminants are retained in the mixed media bed and are removed from the liquid stream.

[0004] In certain industries, adsorbent amendments are dispersed in the mixed media bed to adsorb contaminants in the liquid stream. When the amendments have reached an adsorption capacity, contaminants in the liquid stream are no longer adsorbed by the amendments. In conventional operations, the mixed media bed is discarded when the adsorption capacity is reached. In conventional operations, a new mixed media bed and new amendments must be established in the mixed media bed column to resume contaminant removal. Disposal of the mixed media bed, installation of a new mixed media bed, and introduction of fresh amendment is costly, time-consuming, and wasteful.

[0005] Thus, there is an ongoing need to develop product and process advances that can address one or more of these and related challenges.Docket No. 1710.00077WONON-LIMITING SUMMARY OF THE DISCLOSURE

[0006] This summary lists several embodiments of the presently disclosed subject matter, and in many cases lists variations and permutations of these embodiments. This summary is merely exemplary of the numerous and varied embodiments. The mention of one or more representative features of a given embodiment is likewise exemplary. Such an embodiment can typically exist with or without the feature(s) mentioned; likewise, those features can be applied to other embodiments of the presently disclosed subject matter, whether listed in this summary or not. To avoid excessive repetition, this Summary does not list or suggest all possible combinations of such features.

[0007] A process or method is described to regenerate mixed media beds. The method includes charging a mixed media bed with amendment and contacting the amendment in the mixed media bed with contaminants in a liquid stream until the amendment is spent. The method includes applying backwash liquid flow to the mixed media bed and capturing spent amendment in the backwash liquid flow. The mixed media bed is recharged with fresh amendment to remove additional contaminants from a liquid stream. In a preferred embodiment, charging the mixed media bed with amendment includes adding the amendment to the liquid stream. In another embodiment, the backwash liquid flow is applied when the amendment has reached an adsorption capacity.

[0008] In another embodiment, the mixed media bed includes a plurality of materials disposed in layers in a vertical column. In another embodiment, the method may further include configuring a particle size and density of each of a plurality of materials in the mixed media bed such that the amendment is retained in the mixed media bed when liquid flows through the mixed media bed. In another embodiment, the backwash liquid flows at a rate that lifts the amendment from the mixed media bed but does not lift any media in the mixed media bed out of a column housing the mixed media bed.

[0009] In another embodiment, capturing the spent amendment includes filtering the backwash liquid flow to separate the spent amendment from a clean water stream. In another embodiment, the materials disposed in layers in a vertical column are fluffed and stratified by the backwash liquid flow. In another embodiment, the amendment is comprised of powdered activated carbon. In another embodiment, the amendment is comprised of one or more of biochar, porous carbonaceous materials, zeolites, or ion exchange resins.

[0010] In another embodiment, the method further includes determining that the amendment has reached the adsorption capacity by measuring an amount of the contaminants in an outletDocket No. 1710.00077WO flow of the liquid stream. In another embodiment, a density of each of the plurality of materials is lower than a material in a next lower layer. In another embodiment, the amendment has a lower density than each of the plurality of materials. In another embodiment, the amendment has a smaller particle size than each of the plurality of materials.

[0011] In another embodiment, a flow rate of the backwash liquid is greater than a flow rate of the liquid stream. In another embodiment, the backwash liquid flow is filtered with one or more of a filter press, a sock filter, or a belt filter. In another embodiment, the amendment is configured to adsorb one or more of heavy metals, polycyclic aromatic hydrocarbons, per- and polyfluoroalkyl substances, or volatile organic compounds. In another embodiment, the heavy metals comprise one or more of mercury, chromium, lead, zinc, or any other heavy metal.

[0012] In another embodiment, a method to regenerate mixed media beds includes applying backwash liquid flow to a mixed media bed that includes spent amendment, capturing the spent amendment in the backwash liquid flow, and recharging the mixed media bed with fresh amendment. In another embodiment, the method further includes contacting the fresh amendment in the mixed media bed with contaminants in a liquid stream.

[0013] These and other steps will be discussed in detail below. Thus, the conduct of one or more additional steps beyond those described herein in performing a multi-step process of the disclosure falls within the scope of the claim coverage of this disclosure.

[0014] The above and other embodiments, objectives, features, and advantages of this invention will become still further apparent from the ensuing description, appended claims, and accompanying drawings.BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0015] The presently disclosed subject matter can be better understood by referring to the following example figures. The components in the figure are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the presently disclosed subject matter (often schematically). In the figures, like reference numerals designate corresponding parts throughout the different views. A further understanding of the presently disclosed subject matter can be obtained by reference to an embodiment set forth in the illustrations of the accompanying drawing. Although the illustrated embodiment is merely for purposes of example of systems for carrying out the presently disclosed subject matter, both the organization and method of operation of the presently disclosed subject matter, in general, together with further objectives and advantages thereof, may be more easilyDocket No. 1710.00077WO understood by reference to the drawings and the following description. The drawings are not intended to limit the scope of this presently disclosed subject matter, which is set forth with particularity in the claims as appended or as subsequently amended, but merely to clarify and provide examples of the presently disclosed subject matter.

[0016] FIG. 1 is a block flow diagram of a method to regenerate a mixed media bed in accordance with one embodiment.

[0017] FIG. 2 illustrates a process flow of a mixed media bed in accordance with one embodiment.

[0018] FIG. 3A is a pie chart illustrating amendment losses for a first mixed media bed in accordance with one embodiment.

[0019] FIG. 3B is a pie chart illustrating amendment losses for a second mixed media bed in accordance with one embodiment.

[0020] FIG. 4 illustrates a mass balance of amendment in two different mixed media bed configurations in accordance with one embodiment.DETAILED DESCRIPTION

[0021] Following the Definitions provided below, illustrative aspects of the subject matter claimed even further below will be disclosed. In the interest of clarity, not all features of an actual implementation are described in this specification. It will be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve one of ordinary skill in the art’s specific goals, such as compliance with application-related, system-related and / or business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort, even if complex and time-consuming, would be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.Definitions

[0022] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the presently disclosed subject matter.

[0023] While the following terms are believed to be well understood by one of ordinary skill in the art, the following definitions are set forth to facilitate explanation of the presently disclosed subject matter.

[0024] All technical and scientific terms used herein, unless otherwise defined below, are intended to have the same meaning as commonly understood by one of ordinary skill in theDocket No. 1710.00077WO art. References to techniques employed herein are intended to refer to the techniques as commonly understood in the art, including variations on those techniques or substitutions of equivalent techniques that would be apparent to one of skill in the art. While the following terms are believed to be well understood by one of ordinary skill in the art, the following definitions are set forth to facilitate explanation of the presently disclosed subject matter.

[0025] Components referred to by chemical name or formula anywhere in the specification or claims hereof, whether referred to in the singular or plural, are identified as they exist prior to coming into contact with another substance referred to by chemical name or chemical type (e.g., another component, a solvent, or etc.). It matters not what chemical changes, transformations and / or reactions, if any, take place in the resulting mixture or solution as such changes, transformations, and / or reactions are the natural result of bringing the specified components together under the conditions called for pursuant to this disclosure. Thus, the components are identified as ingredients to be brought together in connection with performing a desired operation or in forming a desired composition. Also, even though the claims hereinafter may refer to substances, components and / or ingredients in the present tense ("comprises", "is", etc.), the reference is to the substance, component or ingredient as it existed at the time just before it was first contacted, blended or mixed with one or more other substances, components and / or ingredients in accordance with the present disclosure. The fact that a substance, component or ingredient may have lost its original identity through a chemical reaction or transformation during the course of contacting, blending or mixing operations, if conducted in accordance with this disclosure and with ordinary skill of a chemist, is thus of no practical concern.

[0026] In describing the presently disclosed subject matter, it will be understood that a number of techniques and steps are disclosed. Each of these has individual benefit and each can also be used in conjunction with one or more, or in some cases all, of the other disclosed techniques.

[0027] Accordingly, for the sake of clarity, this description will refrain from repeating every possible combination of the individual steps in an unnecessary fashion. Nevertheless, the specification and claims should be read with the understanding that such combinations are entirely within the scope of the disclosure and the claims.

[0028] Following long-standing patent law convention, the terms “a”, “an”, and “the” refer to “one or more” when used in this application, including the claims. Thus, for example, reference to "a cell" includes a plurality of such cells, and so forth.Docket No. 1710.00077WO

[0029] Unless otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in this specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the presently disclosed subject matter.

[0030] As used herein, the term “about,” when referring to a value or to an amount of a composition, dose, mass, weight, temperature, time, volume, concentration, percentage, etc., is meant to encompass variations of in some embodiments ±20%, in some embodiments ±10%, in some embodiments ±5%, in some embodiments ±1%, in some embodiments ±0.5%, and in some embodiments ±0.1% from the specified amount, as such variations are appropriate to perform the disclosed methods or employ the disclosed compositions.

[0031] The term “comprising”, which is synonymous with “including” “containing” or “characterized by” is inclusive or open-ended and does not exclude additional, unrecited elements or method steps. “Comprising” is a term of art used in claim language which means that the named elements are essential, but other elements can be added and still form a construct within the scope of the claim.

[0032] As used herein, the phrase “consisting of” excludes any element, step, or ingredient not specified in the claim. When the phrase “consists of’ appears in a clause of the body of a claim, rather than immediately following the preamble, it limits only the element set forth in that clause; other elements are not excluded from the claim as a whole.

[0033] As used herein, the phrase “consisting essentially of” limits the scope of a claim to the specified materials or steps, plus those that do not materially affect the basic and novel characteristic(s) of the claimed subject matter.

[0034] With respect to the terms “comprising,” “consisting of,” and “consisting essentially of,” where one of these three terms is used herein, the presently disclosed and claimed subject matter can include the use of either of the other two terms.

[0035] As used herein, the term “and / or” when used in the context of a listing of entities, refers to the entities being present singly or in combination. Thus, for example, the phrase “A, B, C, and / or D” includes A, B, C, and D individually, but also includes any and all combinations and subcombinations of A, B, C, and D.

[0036] As used herein, the term “concentrated” when used in connection with a solution or in connection with a brine is meant to include a solution or brine that is saturated.Docket No. 1710.00077WOGeneral Procedure

[0037] FIG. 1 is a block flow diagram of a method 100 to regenerate a mixed media bed in accordance with one embodiment.

[0038] In block 102, the method 100 creates a mixed media bed to remove contaminants from a liquid stream. Mixed media beds are typically stratified layers of loose media in a vessel, such as a column. The different layers of a mixed media bed may vary in particle size, density, morphology, or other differences between materials. The materials are often granules, particles, or powders. In examples, the materials are stratified with finer or denser particulates on the bottom of the column and with larger or less dense particles at the top of the column. By stacking the materials with increasing particle sizes or descending densities, larger contaminants are removed closer to the entrance of the mixed media bed and are less likely to plug the media with smaller particle sizes.

[0039] Table 1 represents example bed materials. Other bed materials may be used by other mixed media beds for removing other types of contaminants or for other types of liquids.TABLE 1Docket No. 1710.00077WG

[0040] An example mixed media bed is illustrated in FIG. 2. FIG. 2 illustrates a process flow of a mixed media bed 206 in accordance with one embodiment.

[0041] As illustrated, mixed media bed 206 is a column with four media materials stacked vertically. The coarser and / or lower density materials are at the top of the column. Each successive lower layer has a smaller particle size and / or density. The varying densities and particle sizes allow the media to remain substantially segregated into layers forming a profile because the denser and finer particles settle towards the bottom of each layer. In an example, a top layer may be anthracite, a second layer may be sand, a third layer may be gravel, and a bottom layer may be garnet #8-12.

[0042] Returning to FIG. 1, in block 104, the method 100 charges the mixed media bed 206 with fresh amendment 202. The amendment 202 may be any amendment that adsorbs the desired contaminants from the liquid flow. For example, the amendment 202 may be one or more of activated carbon, biochar, porous carbonaceous materials, zeolites, or ion exchange resins. These amendments 202 or others may be used to selectively adsorb one or more of heavy metals such as mercury, chromium, lead, zinc, etc., polycyclic aromatic hydrocarbons (PAHs), per- and polyfluoroalkyl substances (PFAS), or volatile organic compounds (VOCs). The amendment 202 may further be used to control or remove a color or odor in a liquid stream.

[0043] In a preferred example, the amendment 202 is a powdered amendment with a low density relative to the mixed media. By using an amendment 202 that is of a density that is lower than the bottom material in the mixed media bed 206, the amendment 202 is more consistently retained in the mixed media bed 206 when liquids pass through the mixed media bed 206. In an example, an amendment 202 may be below 40 lbs / ft3in a mixed media bed 206 in which the lowest density media material is 50 lbs / ft3. In another example, the amendment 202 is between 30 and 50 lbs / ft3. In an alternate example, the amendment 202 is below 50 lbs / ft3.

[0044] In other examples, the amendment 202 is a granular amendment. A granular amendment may not require more than a single layer of media in the mixed media bed 206. For example, the granular amendment may reside on top of a bed of garnet #8. In some examples, a granular amendments do not adsorb as efficiently as a powdered amendment. Granular amendments may not infiltrate multiple layers of a mixed media bed 206 as efficiently as a powder. Further, granular amendments may not contact the contaminants as efficiently as a powder.Docket No. 1710.00077WG

[0045] As illustrated in FIG. 2, after selecting a type of amendment 202 to use in the mixed media bed 206, an operator or user may charge the amendment 202 into the mixed media bed 206 by adding the amendment 202 to an inlet stream of liquid. For example, the amendment 202 may be added to a wastewater influent stream 204. The operator may add a quantity of the amendment 202 to a port in the wastewater influent stream 204, add the amendment 202 to a vessel from which the wastewater influent stream 204 is pumped, or add the amendment 202 in any other suitable manner.

[0046] In another example, the amendment 202 is added in a separate liquid stream, such as a fresh water inlet into the mixed media bed 206. In another example, the amendment 202 may be added directly to the mixed media bed 206 in a powder form while a liquid stream is concurrently being added to the mixed media bed 206. The liquid addition serves to disperse the amendment 202 into the mixed media bed 206.

[0047] As the amendment 202 is added to the mixed media bed 206, the amendment 202 is sorted uniformly through the layers. The larger particles of the amendment 202 get captured by the top layers of the mixed media bed 206. Finer particles of the amendment 202 flow through the top layer and flow into the next lower layer. This process continues until the finest particles of the amendment 202 are embedded in the lowest layer of the mixed media bed 206. The mixed media bed 206 is thus charged with the amendment 202.

[0048] When the materials in the mixed media bed 206 are properly selected based on particle size, density, or other factors, the amendment 202 is secured in the mixed media bed 206 and does not pass out of an exit of the mixed media bed 206. In certain examples, during charging, a filter or other collection device may be installed on the exit of the mixed media bed 206 to collect any amendment 202 that passes through the mixed media bed 206.

[0049] Returning to FIG. 1, in block 106, the method 100 directs a contaminated wastewater influent stream 204 through mixed media bed 206 until useful adsorption capacity is reached. For example, an operator may open a valve and / or initiate a pump to cause the wastewater influent stream 204 to be directed into a top of the mixed media bed 206. The wastewater influent stream 204 contacts the top of the mixed media bed 206 and filters through each successive layer.

[0050] As the wastewater influent stream 204 passes through the mixed media bed 206, the water and any contaminants in solution with the water, or being carried by the water, contact the mixed media bed 206 and the amendment 202. The amendment 202 adsorbs at least a portion of the contaminants when contacted. The contaminants are thus removed from theDocket No. 1710.00077WG flow of the wastewater influent stream 204. The liquid in the wastewater influent stream 204 exits the mixed media bed 206 in the low contaminant stream 208. The low contaminant stream 208 will have a lower quantity or number of contaminants than the wastewater influent stream 204 because at least a portion of the contaminants were adsorbed by the amendment 202.

[0051] In some mixed media bed configurations, an amount of the amendment 202 may be carried out of the mixed media bed 206 in the low contaminant stream 208. Optimal designs of mixed media beds 206 and amendment 202 seek to minimize the amount of amendment 202 lost in this manner, as described herein. In an example, a filtration system may be configured to filter the low contaminant stream 208 after exiting the mixed media bed 206. For example, the low contaminant stream 208 may be directed through a sock filter or other filter to capture amendment 202 that has been carried out of the mixed media bed 206. The amendment 202 is a particulate in the low contaminant stream 208 and may be filtered, while the low contaminant stream 208 flows through the filter. Some of the captured amendment may have adsorbed contaminants that require removal from the low contaminant stream 208.

[0052] Each particle of the amendment 202 has a maximum amount of contaminants that may be adsorbed before the particle is spent. When additional contaminants come in contact with the amendment particle, the amendment 202 is unable to adsorb the contaminants. The method 100 may monitor the performance of the amendment 202 in the mixed media bed 206 by testing the contaminants in the low contaminant stream 208. When the level or number of contaminants in the low contaminant stream 208 begin to rise, the amendment 202 may be reaching an adsorption capacity.

[0053] A threshold level of contaminants in the low contaminant stream 208 may be established or configured. For example, the threshold may be at a level of contaminants set by a governmental agency. In another example, an operator may set a threshold below a governmental requirement. In another example, historical data may be used to set a threshold based on a predictable escalation of contaminants in the low contaminant stream 208. When the amendment 202 is no longer able to adsorb a required amount of contaminants, the amendment 202 is determined to be spent amendment 214.

[0054] Returning to FIG. 1, in block 108, the method 100 applies backwash flow to the mixed media bed 206.

[0055] In conventional mixed media bed 206 processes, when the amendment 202 is spent, the mixed media bed 206 with the spent amendment 214 is discarded. For example, theDocket No. 1710.00077WO column may be emptied of the materials that compose the mixed media bed 206 and the entrained spent amendment 214. A new mixed media bed 206 is formed using fresh materials for each layer of the mixed media bed 206. This conventional process requires additional time, costs, and labor to empty, reform, and recharge the mixed media bed 206. In contrast, the method 100 regenerates the mixed media bed 206 by removing the spent amendment 214 and recharging fresh amendment 202 into the mixed media bed 206.

[0056] As illustrated in FIG. 2, the backwash water 210 is applied by pumping water or other suitable liquid into a port at the outlet of the mixed media bed 206. The flow of the backwash water 210 is in an opposite direction of the flow of the wastewater influent stream 204. The backwash water 210 first contacts the bottom layer of the mixed media bed 206 and flows upward towards the top layer of the mixed media bed 206. The backwash water 210 exits the mixed media bed 206 out of the top of the column or vessel housing the mixed media bed 206.

[0057] As the backwash water 210 passes upwards through the mixed media bed 206, spent amendment 214 is dislodged from the material in the mixed media bed 206. As the backwash water 210 flows, the spent amendment 214 is carried with the backwash water 210 out of the mixed media bed 206. In an example, because the spent amendment 214 has a smaller particle size and / or is less dense than the materials in the mixed media bed 206, the spent amendment 214 is carried with the backwash water 210.

[0058] The backwash water 210 may flow at a rate higher than the wastewater influent stream 204 to further dislodge the spent amendment 214 from the mixed media bed 206. For example, a wastewater influent stream 204 may flow at 3.5 gpm / ft2while a backwash water 210 flow may be at 7.5 gpm / ft2. While the flow of the wastewater influent stream 204 is not enough to wash the amendment 202 out of the low contaminant effluent 208, the flow of the backwash water 210 is enough to wash the spent amendment 214 out of the top of the mixed media bed 206.

[0059] A flow rate of the backwash water 210 is set such that the spent amendment 214 is carried out of the mixed media bed 206 but the materials of the mixed media bed 206 are not. For example, if a flow rate of the backwash water 210 is too high, then some or all of the materials in the mixed media bed 206 are carried out. If the flow rate of the backwash water 210 is too low, then the spent amendment 214 will not be carried out. A flow rate is selected that carries out the spent amendment 214 but not the material of the mixed media bed 206. The flow of the backwash water 210 further fluffs the materials in the mixed media bed 206Docket No. 1710.00077WG to cause the materials to reform the layers into a segregated layer profile. When fluffed or disturbed by the upward flow of the backwash water 210, the materials will resettle into layers based on the particle size, density, or other factors described herein.

[0060] Returning to FIG. 1, in block 110, the method 100 captures the spent amendment 202.

[0061] As illustrated in FIG. 2, the backwash water 210 flows into a particulate filter 216. The filter 216 may be any suitable type of filter that removes the spent amendment 214 from the backwash water 210. For example, the filter 216 may be a sock filter, a filter press, a belt filter, a candle filter, a cartridge filter, or any other suitable filter for removing particulates from a liquid stream.

[0062] When the filter 216 captures the spent amendment 214 from the backwash water 210, a clean water stream 212 exits the filter 216. The clean water stream 212 may be reused as backwash water 210, released into the environment, or recycled in any suitable stream. The spent amendment 214 may be disposed of or recycled. For example, the contaminants may be reclaimed from the spent amendment 214 for any suitable use.

[0063] Returning to FIG. 1, in block 112, the method 100 recharges the mixed media bed 206 with fresh amendment 202.

[0064] After the spent amendment 214 is removed from the mixed media bed 206 via the backwash water 210, the mixed media bed 206 is charged with fresh amendment 202, as described in block 104. The charged mixed media bed 206 is again available to remove contaminants from the wastewater influent streams 204.

[0065] In an example process, two columns with mixed media beds 206 are used in a system to remove contaminants from wastewater influent streams 204. In the example, when the amendment 202 in a first mixed media bed 206 is spent, the wastewater influent stream 204 may be stopped to allow the mixed media bed 206 to be regenerated as described herein. The second column with a charged mixed media bed 206 filters the wastewater influent stream 204 as described herein while the first mixed media bed 206 is backwashed and charged. When the first mixed media bed 206 is back online, the second mixed media bed 206 may be regenerated when required. In this example process, wastewater influent stream 204 may be continuously filtered by one or both mixed media beds 206 without interruption for regeneration.Docket No. 1710.00077WOEXAMPLE 1

[0066] FIG. 3A is a pie chart illustrating amendment losses for a first mixed media bed in accordance with one embodiment. FIG. 3B is a pie chart illustrating amendment losses for a second mixed media bed in accordance with one embodiment..

[0067] As described herein, mixed media beds 206 typically consist of two or more layers of different types of materials. The differences between the materials can be particle size, density, morphology, etc. The choice of materials, the thickness of the material layers, and the order of the layers determine the performance of the bed for distribution of the amendment 202, for flow patterns of the wastewater influent stream 204, for retention of the amendment 202, for backwash water 210 flow rates, and for other parameters of the mixed media bed 206.

[0068] An example of this is displayed in FIG. 3A and FIG. 3B. The bed design for the two mixed media beds 206 was tested to determine the amount of amendment that was lost during the regeneration cycle of the amendment 202. For example, when the mixed media bed 206 was being charged with amendment 202, the amount of amendment 202 that exited through an outlet of the column was measured. The amount of amendment 202 that was lost through the low contaminant stream 208 during normal contaminant filtering operation was measured. The amount of spent amendment 214 that was captured by the filter 216 during the backwash phase was measured.

[0069] In an ideal configuration of the mixed media bed 206, the amount of amendment that escapes through an outlet during charging would be minimized. Amendment 202 lost during charging does not serve to capture any contaminants. Further, configurations are preferred in which the amendment 202 lost through the low contaminant stream 208 during normal operation is minimized. The amendment 202 lost during normal operation may have captured some portion of the contaminants. Ideally, configurations are preferred in which the amount of spent amendment 214 captured during the backwash process is maximized. The spent amendment 214 has captured some amount of contaminants and is collected for disposal during the backwash process.

[0070] In the examples, the mixed media bed 206 of FIG. 3A was less capable of capturing and holding the powdered amendment than mixed media bed 206 of FIG. 3B. As illustrated, the mixed media bed 206 of FIG. 3A lost 48% of the amendment 202 during charging. In this example, nearly half of the powdered amendment 202 was not retained by the materials in the mixed media bed 206 but flowed out of the mixed media bed 206. Only 21% of theDocket No. 1710.00077WG amendment 202 was collected as spent amendment 214 after filtering out the contaminants. Conversely, the mixed media bed 206 of FIG. 3B lost only 1% of the amendment 202 during charging. In this example, nearly all of the powdered amendment 202 was retained by the materials in the mixed media bed 206. Over 44% of the amendment 202 was collected as spent amendment 214 after filtering out the contaminants.

[0071] Therefore, the mixed media bed 206 of FIG. 3B was a more desirable bed design. Example 1 is not purported as a optimal design. The comparison of FIG. 3A and FIG. 3B illustrates that a bed design for the mixed media bed 206 can be optimized to improve certain features of the operation of the method 100. Other examples and other mixed media beds 206 may provide improved retention of the amendment 202 and filtration of the contaminants.EXAMPLE 2

[0072] FIG. 4 illustrates a mass balance of amendment in two different configurations of mixed media beds 206 in accordance with one embodiment.

[0073] The mass balance of amendment 202 in the mixed media bed 3 and mixed media bed 4 are plotted on a line graph. The graph illustrates the amount of amendment in the columns over two recharges and at varying flow rates during standard flow. Mixed media bed 3 illustrates an improvement over the retention of amendment 202 in mixed media bed 4.

[0074] In each of the mixed media beds of Example 2, 13g of amendment 202 is charged into the mixed media bed 206. In mixed media bed 3, nearly all 13g of amendment 202 are retained as illustrated in the “after charge” plot. In mixed media bed 4, only 8.3 g of amendment 202 are retained in the column. The remaining amendment 202 exited the mixed media bed 4 with the water used during charging.

[0075] Standard flow rates for the wastewater influent stream 204 were used during the testing, 1.6 gpm / ft2, 2 gpm / ft2, 3.5 gpm / ft2, and 5 gpm / ft2. As illustrated with increased flow rates, a greater percentage of the amendment 202 exits mixed media beds 3 and 4 via the low contaminant stream 208. However, mixed media bed 3 retained the most amendment 202 throughout each flow rate.

[0076] When configuring the operating conditions of mixed media beds 206, a user may weigh such factors as the amount of amendment 202 that needs to be retained, the flow rates that are required to filter a required amount of water, the amount of amendment 202 that may be released in the low contaminant stream 208, and other factors. For example, at the 2Docket No. 1710.00077WO gpm / ft2flow rate, 90 wt% of the amendment remains in the bed for mixed media bed 3, but this flow rate may not accomplish the required goals of the method.

[0077] Each of the mixed media beds 3 and 4 were exposed to a backwash flow to recover the spent amendment 214. For mixed media bed 3, at a backwash flow rate of 7.5 gpm / ft2, 3g of the spent amendment 214 is discharged, and 6.2g of the original 13g remains in the bed. It is expected that a higher ratio of the original amendment charge would have been removed if the test were run with a lower flow rate during standard operations.

[0078] During recharge, 13g of additional amendment 202 were charged into the mixed media bed 3 resulting in over 18g of amendment 202 in the mixed media bed 3.

[0079] The trends illustrated in FIG. 3A, FIG. 3B, and FIG. 4 illustrate that the concept of a regenerable mixed media bed 206 is fullly enabled. Additional optimization of bed design and backwash procedures may increase the retention capability of an amendment 202 and increase the removal of the spent amendment 214 during regeneration.

[0080] While the present disclosure has been described in terms of one or more preferred embodiments, it is to be understood that other modifications may be made without departing from the scope of the disclosure, which is set forth in the claims below.

Claims

Docket No. 1710.00077WOCLAIMSThat which is claimed is:

1. A method of regenerating mixed media beds, the method comprising: charging a mixed media bed with amendment; contacting the amendment in the mixed media bed with contaminants in a liquid stream; applying backwash liquid flow to the mixed media bed; capturing spent amendment in the backwash liquid flow; and recharging the mixed media bed with fresh amendment.

2. The method of claim 1, wherein charging the mixed media bed with amendment comprises adding the amendment to the liquid stream.

3. The method of claim 1 or 2, wherein the backwash liquid flow is applied when the amendment has reached an adsorption capacity.

4. The method of claim 3, further comprising determining that the amendment has reached the adsorption capacity by measuring an amount of the contaminants in an outlet flow of the liquid stream.

5. The method of any one of claims 1 to 3, wherein the mixed media bed comprises a plurality of materials disposed in layers in a vertical column.

6. The method of claim 5, wherein a density of each of the plurality of materials is lower than a material in a next lower layer.

7. The method of claim 5 or 6, wherein the amendment has a lower density than each of the plurality of materials.

8. The method of any one of claims 5 to 7, wherein the amendment has a smaller particle size than each of the plurality of materials.

9. The method of any one of claims 1 to 8, further comprising configuring a particle size and density of each of a plurality of materials in the mixed media bed such that the amendment is retained in the mixed media bed when liquid flows through the mixed media bed.Docket No. 1710.00077WO10. The method of any one of claims 1 to 9, wherein the backwash liquid flows at a rate that lifts the amendment from the mixed media bed but does not lift any media in the mixed media bed out of a column housing the mixed media bed.

11. The method of any one of claims 1 to 10, wherein a flow rate of the backwash liquid is greater than a flow rate of the liquid stream.

12. The method of any one of claims 1 to 11, wherein capturing the spent amendment comprises filtering the backwash liquid flow to separate the spent amendment from a clean water stream.

13. The method of claim 12, wherein the backwash liquid flow is filtered with one or more of a filter press, a sock filter, a belt filter, a candle filter, or a cartridge filter.

14. The method of any one of claims 1 to 13, wherein the materials disposed in layers in a vertical column are fluffed and stratified by the backwash liquid flow.

15. The method of any one of claims 1 to 14, wherein the amendment is comprised of powdered activated carbon.

16. The method of any one of claims 1 to 15, wherein the amendment is comprised of one or more of biochar, porous carbonaceous materials, zeolites, or ion exchange resins.

17. The method of claim 15 or 16, wherein the amendment is configured to adsorb one or more of heavy metals, polycyclic aromatic hydrocarbons, per- and polyfluoroalkyl substances, or volatile organic compounds.

18. The method of claim 17, wherein the heavy metals comprise one or more of mercury, chromium, lead, or zinc.1 . A method of regenerating mixed media beds, the method comprising: applying backwash liquid flow to a mixed media bed that comprises spent amendment; capturing the spent amendment in the backwash liquid flow; and recharging the mixed media bed with fresh amendment.

20. The method of claim 19, further comprising contacting the fresh amendment in the mixed media bed with contaminants in a liquid stream.

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