Waste Recycling System and Method

Abstract

A system and method for waste regeneration that regenerates dissolved molybdenum (Mo) and filters heavy metals from process wash water containing Mo for on-site disposal. The system and method reduce incidental costs by converting liquid byproducts into solid byproducts and converting Mo dissolved in solution into a solid form that can be converted into a base metal.

Description

Technology Field

[0001] Cross-reference regarding related applications

[0002] This application claims priority to U.S. Provisional Application No. 63 / 615,974, filed with the U.S. Patent and Trademark Office on December 29, 2023, and U.S. Utility Model Application No. 19 / 001,698, filed on December 26, 2024. The full contents of their disclosures are incorporated herein by reference.

[0003] Field of invention

[0004] The present invention relates to a waste recycling system and method, particularly a waste recycling system and method that can be efficiently used in a radiation-sensitive environment. Background Technology

[0005] Process wastewater from certain nuclear facilities can contain up to 2,000 ppm of molybdenum (Mo) before discharge. There is a need to find a method to treat the waste instead of bulk disposal of non-hazardous waste.

[0006] In addition, systems and methods are needed that can be used efficiently in radiation-sensitive environments and further reduce production costs. Systems and methods are also needed to return water to the municipal water supply system.

[0007] The system and method of the present invention satisfy these requirements.

[0008] The present invention relates to a system and method for waste regeneration that regenerates dissolved molybdenum (Mo) and filters heavy metals from process wash water containing Mo for on-site disposal. The system and method reduce incidental costs by converting liquid by-products into solid by-products, converting Mo dissolved in solution into a solid form, and then converting it into a base metal.

[0009] According to one aspect of the present invention, a waste recycling method is provided, comprising the following steps: measuring the concentration of molybdenum (Mo) in a liquid byproduct; adding to the liquid byproduct a salt or another water-soluble compound containing an element selected from the group consisting of mercury, lead, thorium, sulfur, and combinations thereof; mixing until substantially all or all of the salt or water-soluble compound is dissolved in the solution; providing a predetermined period for the solution to precipitate to form a process water precipitate; and passing the process water precipitate through a guard filter or an activated carbon column to filter out the MoO4-containing compound.

[0010] According to one aspect of the present invention, the method further comprises passing a process flow from a guard filter or an activated carbon column through a first mechanical filter or a first filter cartridge containing a filter medium.

[0011] According to one aspect of the present invention, the first mechanical filter or filter medium is a rust removal and sedimentation filter.

[0012] According to one aspect of the present invention, the method further comprises filtering a flow from a first filter cartridge through a second mechanical filter or a second filter cartridge containing a filter medium.

[0013] According to one aspect of the present invention, the second mechanical filter or filter medium is a drinking water filter pellet.

[0014] According to one aspect of the present invention, the method further comprises passing the flow from a second filter cartridge through a third filter cartridge packed with Al2O3.

[0015] According to one aspect of the present invention, Al2O3 exists as an alumina powder layer.

[0016] According to one aspect of the present invention, the method further comprises passing a flow from a third filter cartridge packed with Al2O3 through a fourth cartridge packed with sandstone sedimentation rock to filter water and collect alumina fine particles.

[0017] According to one aspect of the present invention, the method further comprises passing a flow through a chromatography column packed with an ion exchange resin to remove residual soluble metal species. According to one aspect of the present invention, the ion exchange resin is a chitosan-based ion exchange resin.

[0018] According to one aspect of the present invention, the method further comprises passing a flow from a third filter cartridge packed with Al2O3 through an ion exchange resin to remove soluble metal chemical species. According to one aspect of the present invention, the ion exchange resin is a chitosan-based ion exchange resin.

[0019] According to one aspect of the present invention, a waste recycling method is provided comprising the following steps: measuring the concentration of molybdenum (Mo) in a liquid byproduct; adding to the liquid byproduct a salt or another water-soluble compound containing an element selected from the group consisting of mercury, lead, thorium, sulfur, and combinations thereof; mixing until substantially all or all of the salt or water-soluble compound is dissolved in the solution; providing a predetermined period for the solution to precipitate to form a process water precipitate; passing the process water precipitate through a guard filter or an activated carbon column to filter out the MoO4-containing compound; and converting Mo from the solid byproduct into a base metal.

[0020] According to one aspect of the present invention, a waste recycling method is provided, comprising the following steps: measuring the concentration of molybdenum (Mo) in a liquid byproduct; adding CaCl2 to the liquid byproduct; mixing until substantially all or all of the CaCl2 is dissolved in the solution; providing a predetermined period for the solution to precipitate to form a process water precipitate; and passing the process water precipitate through a guard filter or an activated carbon column to filter out CaMoO4.

[0021] According to one aspect of the present invention, the method further comprises passing a process flow from a guard filter or an activated carbon column through a first mechanical filter or a first filter cartridge containing a filter medium. According to one aspect of the present invention, the first mechanical filter or filter medium is a rust removal and sedimentation filter.

[0022] According to one aspect of the present invention, the method further comprises filtering a flow from a first filter cartridge through a second filter cartridge containing a second mechanical filter or filter medium. According to one aspect of the present invention, the second mechanical filter or filter medium is a drinking water filter pellet.

[0023] According to one aspect of the present invention, the method further comprises passing the flow from a second filter cartridge through a third filter cartridge packed with Al2O3.

[0024] According to one aspect of the present invention, the method further comprises passing a flow from a second filter cartridge through a third filter cartridge packed with Al2O3. According to one aspect of the present invention, Al2O3 exists as an alumina powder layer.

[0025] According to one aspect of the present invention, the method further comprises passing a flow from a third filter cartridge packed with Al2O3 through a fourth cartridge packed with sandstone sedimentation rock to filter water and collect alumina fine particles.

[0026] According to one aspect of the present invention, the method further comprises passing a flow through a chromatography column packed with an ion exchange resin to remove soluble metal chemical species. According to one aspect of the present invention, the ion exchange resin is a chitosan-based ion exchange resin.

[0027] According to one aspect of the present invention, the method further comprises passing a flow from a third filter cartridge packed with Al2O3 through an ion exchange resin to remove soluble metal chemical species. According to one aspect of the present invention, the ion exchange resin is a chitosan-based ion exchange resin.

[0028] According to one aspect of the present invention, a waste recycling method is provided comprising the following steps: measuring the concentration of molybdenum (Mo) in a liquid byproduct; adding CaCl2 to the liquid byproduct; mixing until substantially all or all of the CaCl2 is dissolved in the solution; providing a predetermined period for the solution to precipitate to form a process water precipitate; passing the process water precipitate through a guard filter or an activated carbon column to filter out CaMoO4; and converting Mo from the solid byproduct into a base metal.

[0029] Approximately 50 to 100 gallons per day can be treated by the system and method of the present invention. Chemical precipitation of the wastewater can reduce the Mo content to less than 100 ppm. After precipitation, the liquid stream is filtered using a mechanical medium. The liquid stream is also optionally applied to ion exchange in the form of activated alumina and organic resin to reduce the final Mo concentration to 5 ppm to 40 ppm. The treatment flow rate after precipitation can be approximately 0.25 gallons per minute. Samples can be collected after each stage. The ion exchange step is repeated until the Mo level is below the discharge level required by CFR 433.17. At these stages, the final sample may be collected as a retaining, and the bulk liquid may be discharged into municipal sewer.

[0030] Further applications of the present invention will become apparent from the detailed description provided below. It should be understood that while the detailed description and specific examples indicate preferred embodiments of the present invention, they are merely illustrative and are not intended to limit the scope of the invention. Brief explanation of the drawing

[0031] The present invention will be more fully understood from the detailed description and the accompanying drawings, which do not necessarily represent a fixed proportion, wherein: FIG. 1 illustrates a process water regeneration system and method including a small-scale filtration flow path according to one aspect of the present invention. FIG. 2 illustrates a process water regeneration system and method including a large-scale filtration flow path according to one aspect of the present invention. Specific details for implementing the invention

[0032] The following description regarding embodiments of the present invention is essentially merely illustrative and is not intended to limit the invention, its application, or its use in any way. The following description is provided herein merely as an example for the purpose of providing a feasible disclosure of the invention and does not limit the scope or nature of the invention.

[0033] The system and method of the present invention reduce incidental costs by converting liquid by-products into solid by-products, converting molybdenum (Mo) dissolved in a solution into a solid form, and then converting it into a base metal. Additionally, this system and method can be used efficiently in radiation-sensitive environments and can further reduce production costs.

[0034] In one aspect of the present invention, a method comprises collecting a liquid byproduct and measuring the concentration of molybdenum (Mo) in the liquid byproduct. Using the measured Mo concentration, a solution is formed by adding a salt (including but not limited to calcium chloride) or another water-soluble compound containing an element selected from the group consisting of mercury, lead, thorium, sulfur, and combinations thereof to the liquid byproduct, and allowing the mixture to be mixed for a predetermined period.

[0035] For example, in the case of calcium chloride (CaCl2), CaCl2 is added to the process water barrel at a molar ratio of at least 3:1 to Mo (e.g., 1000 ppm Mo requires ~1.5 kg of CaCl2).

[0036] Mixing of the waste and solution can be performed using a fixed-blade impeller driven by a brushless drill. Mixing is performed until substantially all or all of the salt or water-soluble compound is dissolved. The amount of time may vary, but typically it can be about 2 to 3 minutes.

[0037] The method additionally involves allowing the solution to precipitate. During testing, the solution becomes slightly cloudy in the presence of white fine particles. After mixing for a longer period, for example, more CaMoO4 precipitates. Molybdenum anion (MoO4 -2 ) and calcium cations (Ca 2+ When combined in this solution, calcium molybdate (CaMoO4) precipitates. When CaCl2 is used with ammonium molybdate ((NH4)2MoO4), CaMoO4 may precipitate.

[0038] This solution of MoO4-containing compounds and residual byproduct liquid, also referred to herein as "process water precipitate," is filtered through a process water regeneration system that includes filtration.

[0039] Referring to the drawings, FIG. 1 illustrates a process water regeneration system and method of the present invention comprising a small-scale filtration flow path. As shown in FIG. 1, in an exemplary case where calcium chloride is used, the process water sediment from the sedimentation tank (10) is pumped through an activated carbon column (20) to filter out CaMoO4 and then enters a retention tank (30). The water therefrom passes through a pressure relief valve (40) and is filtered through a plurality of cartridges using a diaphragm pump, for example, through a series of four cartridges as shown. Two types of flow streams flow out of the pressure relief valve (40), one returns to the retention tank (30), and the other flows to a first filter cartridge. The first cartridge is a rust removal and sedimentation filter (50), and the second cartridge is a drinking water filter pellet (60), both of which act as mechanical filters for any remaining CaMoO4. The third cartridge is packed with Al2O3 (70), which further isolates residual soluble metal species found in the byproduct liquid, and the fourth cartridge is packed with sandstone precipitate (80), which not only further filters the water but also captures any alumina fine particles that have passed through the previous cartridges. After being filtered through all four cartridges, the water is then pumped through a chromatography column (90) filled with a chitosan-based ion exchange resin to remove any residual small amount of soluble metal species. The resulting stream of flow is then introduced into a discharge tank (95).

[0040] FIG. 2 illustrates a process water regeneration system and method comprising a large-scale filtration flow path according to one aspect of the present invention. As shown in FIG. 2, in an exemplary case where calcium chloride is used, the process water precipitate is pumped from a precipitation tank (100) through a guard filter (120) (e.g., 50-μm) to a retention tank (130) to isolate the liquid from the precipitated solid. The guard filter (120) is positioned inline during transport to capture any CaMoO4 that passes through. Subsequently, the solution is pumped from the retention tank (130) through a pressure relief valve (140) and a plurality of filter cartridges. Two types of flow streams flow out of the pressure relief valve (140), one returning to the retention tank (130) and the other flowing to a first filter cartridge, which is a rust removal and precipitation cartridge (150). The second cartridge has a mixture (160) of resin and γAl2O3 pellets that acts as a filter layer to hold the resin in place, as well as another adsorbent for molten metal. The third cartridge has an alumina powder layer (170). An optional fourth cartridge is filled with γAl2O3 pellets to properly hold the packed resin, as well as ion exchange resin (180). The flow thus produced enters a discharge tank (195).

[0041] Examples

[0042] For the test, approximately 4.5 gallons (17 L) of byproduct liquid was collected in a 5-gallon bucket. 200 grams of CaCl2 were added to the 5-gallon bucket and allowed to mix for 10 minutes. Upon inspection, a white film began to coat the walls of the bucket, and the solution became slightly turbid in the presence of white particulates. After mixing overnight, more CaMoO4 precipitated. Subsequently, this solution of CaMoO4 and the remaining byproduct liquid was sampled and filtered through a filtration system prototype for further testing.

[0043] Max-scale sedimentation was performed using 40 gallons of collected byproduct liquid as a small-scale test. Byproduct liquid was obtained from three different batches to simulate full-pilot process water production. Semi-quantitative measurements of the starting Mo concentration were performed. The pH was adjusted to 7.5 using concentrated sodium hydroxide (NaOH). Subsequently, using the estimated concentration, CaCl2 (~1.5 kg) at a 3:1 ratio to Mo was added while mixing into a 40-gallon (151 L) barrel of byproduct liquid. After mixing for 3 to 5 minutes, the pH of the solution decreased to 6.4. After mixing the barrel of process water for 3 to 4 hours, the solid was allowed to settle overnight. The solution was not mixed for at least 12 hours. All precipitated CaMoO4 settled at the bottom of the barrel, leaving the solution clear. The water was then carefully pumped into a retention barrel for further treatment through a filtration system.

[0044] Therefore, a person skilled in the art will readily understand that the present invention may have extensive utility and applicability. Without departing from the nature or scope of the invention, many embodiments and variations of the invention other than those described herein, as well as many changes, modifications, and equivalents, will be apparent or reasonably inferred from the invention and the foregoing description relating thereto. Accordingly, although the invention has been described in detail herein with respect to its preferred embodiments, it should be understood that the foregoing disclosure is merely illustrative and descriptive of the invention and is intended to provide sufficiently feasible disclosures of the invention. The foregoing disclosures should not be intended or interpreted to limit the invention or otherwise exclude any such other embodiments, variations, changes, modifications, and equivalents.

Claims

Claim 1 A waste recycling method comprising the following steps: measuring the concentration of molybdenum (Mo) in a liquid byproduct; adding to the liquid byproduct a salt or another water-soluble compound containing an element selected from the group consisting of mercury, lead, thorium, sulfur, and combinations thereof; mixing until substantially all or all of the salt or water-soluble compound is dissolved in the solution; providing a predetermined period for the solution to precipitate to form a process water precipitate; and passing the process water precipitate through a guard filter or an activated carbon column to filter out the MoO4-containing compound. Claim 2 A method according to claim 1, further comprising passing a process flow from a guard filter or an activated carbon column through a first mechanical filter or a first filter cartridge containing a filter medium. Claim 3 In paragraph 2, the method wherein the first mechanical filter or filter medium is a rust removal and sedimentation filter. Claim 4 A method according to paragraph 2, further comprising filtering the flow from a first filter cartridge through a second mechanical filter or a second filter cartridge containing a filter medium. Claim 5 In paragraph 4, the method wherein the second mechanical filter or filter medium is a drinking water filter pellet. Claim 6 A method according to claim 4, further comprising passing the flow from the second filter cartridge through a third filter cartridge packed with Al2O3. Claim 7 In claim 6, the method in which Al2O3 exists as an alumina powder layer. Claim 8 A method according to claim 6, further comprising passing a flow from a third filter cartridge packed with Al2O3 through a fourth cartridge packed with sandstone sedimentation rock to filter water and collect alumina fine particles. Claim 9 A method according to claim 8, further comprising passing the flow through a chromatography column filled with an ion exchange resin to remove residual soluble metal chemical species. Claim 10 In claim 9, the method wherein the ion exchange resin is a chitosan-based ion exchange resin. Claim 11 A method according to claim 1, further comprising converting Mo from a solid byproduct into a base metal. Claim 12 A method according to claim 6, further comprising passing a flow from a third filter cartridge packed with Al2O3 through an ion exchange resin to remove soluble metal chemical species. Claim 13 In paragraph 12, the method wherein the ion exchange resin is a chitosan-based ion exchange resin. Claim 14 A waste recycling method comprising the following steps: measuring the concentration of molybdenum (Mo) in a liquid byproduct; adding CaCl2 to the liquid byproduct; mixing until substantially all or all of the CaCl2 is dissolved in the solution; providing a predetermined period for the solution to precipitate to form a process water precipitate; and passing the process water precipitate through a guard filter or an activated carbon column to filter out CaMoO4. Claim 15 A method according to claim 14, further comprising passing a process flow from a guard filter or an activated carbon column through a first mechanical filter or a first filter cartridge containing a filter medium. Claim 16 In paragraph 15, the method wherein the first mechanical filter or filter medium is a rust removal and sedimentation filter. Claim 17 A method according to claim 15, further comprising filtering the flow from a first filter cartridge through a second mechanical filter or a second filter cartridge containing a filter medium. Claim 18 In paragraph 17, the method wherein the second mechanical filter or filter medium is a drinking water filter pellet. Claim 19 A method according to claim 17, further comprising passing the flow from the second filter cartridge through a third filter cartridge packed with Al2O3. Claim 20 In paragraph 19, the method in which Al2O3 exists as an alumina powder layer. Claim 21 A method according to claim 19, further comprising passing a flow from a third filter cartridge packed with Al2O3 through a fourth cartridge packed with sandstone sedimentation rock to filter water and collect alumina fine particles. Claim 22 A method according to claim 21, further comprising passing a flow through a chromatography column filled with an ion exchange resin to remove soluble metal chemical species. Claim 23 In paragraph 22, the method wherein the ion exchange resin is a chitosan-based ion exchange resin. Claim 24 A method according to claim 14, further comprising converting Mo from a solid byproduct into a base metal. Claim 25 A method according to claim 19, further comprising passing a flow from a third filter cartridge packed with Al2O3 through an ion exchange resin to remove soluble metal chemical species. Claim 26 In paragraph 25, the method wherein the ion exchange resin is a chitosan-based ion exchange resin.

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