System and method for removing perchlorate from contaminated aqueous liquids

Abstract

There is provided a process of treating an aqueous liquid. The aqueous liquid is received containing organic contaminants and chloride. Hydrogen peroxide is added to the aqueous liquid and the aqueous liquid is acidified to maintain an acidic pH of up to 5. The organic contaminants in the aqueous liquid are degraded in a reactor to obtain residual organic contaminants while perchlorate is formed. The residual organic contaminants and perchlorate are absorbed from the aqueous liquid by exposing the aqueous liquid to activated carbon.

Description

SYSTEM AND METHOD FOR REMOVING PERCHLORATE FROM CONTAMINATED AQUEOUS LIQUIDS CROSS-REFERENCE TO RELATED APPLICATION

[0001] The present application claims the benefit of United States Patent Application No. 63 / 748,704, filed on January 23, 2025 and incorporated herein by reference.TECHNICAL FIELD

[0002] The application relates to the treatment of aqueous liquids such as wastewater, particularly contaminated aqueous liquids that include perchlorate or are susceptible of producing perchlorate when treated.BACKGROUND

[0003] The main technologies to treat perchlorate in water are biological treatments and phytoremediation for high perchlorate concentrations, or even chemical reduction (such as zero valent ion), fluidized bed, ion exchange resin (IEX), membrane filtration and adsorption for low perchlorate concentrations.

[0004] Conventional treatments for perchlorate abatement have disadvantages of large footprint (long residence times), of long times required to reach steady state (biological treatment), of using relatively expensive materials (zero valent iron or catalysts), and / or of being relatively complex to implement or to operate.

[0005] Technologies to destroy perfluoroalkyl and polyfluoroalkyl substances (PFAS) in water such as electro-oxidation often produce perchlorate if chloride ions are present in the water. Therefore, there is a need for a technology that can destroy PFAS in water while removing perchlorate from water. PFAS are used in a multitude of industries such as pharmaceuticals, automotive, cosmetics, and electronics. Because of their ubiquity, PFAS end up accumulating in wastewater. PFAS do not easily degrade and remain in the environment for prolonged periods of time. Therefore, they are a pollutant that remains in the environment and that can contaminate water and soils, which is a concern because PFAS can cause health issues.

[0006] It would be desirable to have an improved process capable of treating wastewater containing or susceptible of producing perchlorates when treated. Particularly, a process with a shorter residence time, a reduced cost and increased user friendliness when compared to conventional processes is desired.SUMMARY

[0007] In one aspect, there is provided a process of treating an aqueous liquid, the process comprising: receiving the aqueous liquid including organic contaminants and chloride; adding hydrogen peroxide to the aqueous liquid; acidifying the aqueous liquid to maintain an acidic pH of up to 5; degrading the organic contaminants in a reactor to obtain residual organic contaminants while perchlorate is formed; and adsorbing the residual organic contaminants and perchlorate from the aqueous liquid by exposing the aqueous liquid to activated carbon.

[0008] The process described above may include any of the following features, in any combinations.

[0009] In some embodiments, receiving the aqueous liquid including the organic contaminants includes receiving the aqueous liquid including perfluoroalkyl and polyfluoroalkyl substances (PFAS).

[0010] In some embodiments, degrading the organic contaminants in the reactor includes degrading the organic contaminants in an electro-oxidation reactor. In some embodiments, degrading the organic contaminants in the electro-oxidation reactor includes degrading the organic contaminants with one or more of boron-doped diamond electrodes.

[0011] In some embodiments, the process further comprises filtering the aqueous liquid to separate out suspended solids before degrading the organic contaminants.

[0012] In some embodiments, the process further comprises maintaining a temperature of the aqueous liquid between 35 and 65°C, inclusively.

[0013] In some embodiments, the step of adding the hydrogen peroxide to the aqueous liquid includes maintaining the hydrogen peroxide in the aqueous phase at a concentration of from 50 to 200 mM.

[0014] In some embodiments, the step of acidifying comprises adding H2SO4.

[0015] In a further aspect, there is provided a system for treating an aqueous liquid, the system comprising: a recirculation loop including: a transfer reservoir for receiving the aqueous liquid including organic contaminants and chloride, one or more reactors for degrading the organic contaminants in the aqueous liquid to obtain residual organic contaminants and in which perchlorate is produced, an acid source in fluid communication with the recirculation loop for adding an acid into the aqueous liquid, a hydrogen peroxide source in fluid communication with the recirculation loop for adding hydrogen peroxide to the aqueous liquid, and at least one conduit for fluidly connecting the transfer reservoir, the one or more reactors; and one or more activated carbon adsorption filters downstream of the recirculation loop for adsorbing the residual organic contaminants and perchlorate.

[0016] The system described above may include any of the following features, in any combinations.

[0017] In some embodiments, the system further comprises a filter upstream of the recirculation loop to remove suspended solids from the aqueous liquid.

[0018] In some embodiments, the recirculation loop further comprises a cooling system for cooling the aqueous liquid.

[0019] In some embodiments, the conduit includes a recirculation pump to recirculate the aqueous liquid between the reservoir and the one or more reactors.

[0020] In some embodiments, the organic contaminants include perfluoroalkyl and polyfluoroalkyl substances (PFAS).

[0021] In some embodiments, the reactor is an electro-oxidation reactor.

[0022] In some embodiments, wherein the electro-oxidation reactor includes one or more boron-doped diamond electrodes.DESCRIPTION OF THE DRAWINGS

[0023] Reference is now made to the accompanying figures in which:

[0024] Fig. 1 is a block diagram of a system for treating an aqueous liquid in accordance with the present disclosure;

[0025] Fig. 2 is a process flow diagram of a process for treating an aqueous liquid in accordance with the present disclosure;

[0026] Fig. 3 is a legend for symbols used in a schematic diagram of an exemplary configuration of the system for treating an aqueous liquid in accordance with the present disclosure; and

[0027] Figs. 4-6 concurrently form a schematic diagram of an exemplary configuration of the system for treating an aqueous liquid of Fig. 1.DETAILED DESCRIPTION

[0028] The present process relates to the treatment of a contaminated aqueous liquid in which perchlorate is present or perchlorate is susceptible of being produced when the aqueous liquid is treated. This is the case for example when the aqueous water contains organic contaminants and chloride. Some of the widespread organic contaminants are perfluoroalkyl and polyfluoroalkyl substances (PFAS). Accordingly, one exemplary aspect of the present process is the destruction of PFAS and / or other difficult to treat contaminants (such as recalcitrant) by electro-oxidation (EO) while removing perchlorate which may be formed by the EO in liquid streams of any sort. There is therefore presently provided a system and a process for the destruction of PFAS in an aqueous liquid while removing perchlorate generated by the EO. However, as explained above, the present process is applicable to contaminants beyond PFAS and can also be used for the destruction of other difficult to treat organic contaminants in aqueous liquid where chloride ions are present, and perchlorate can be electro-chemically formed. Such organic contaminants known to be destroyed byEO are for example ethanol, phenol, acetone, methanol, formaldehyde, pesticides, pharmaceutical compounds, and cosmetic compounds. The aqueous liquid can for example be groundwater contaminated at airports, military bases or any other PFAS impacted sites, wastewater from chemical and cosmetic manufacturers, landfills, oil and gas refineries, mines, municipalities with their firing practice station, electroplating plant, concentrate from reverse osmosis, ion exchange regenerative waste solution and foam fractionation liquid waste, leachate, industrial water, wash water, stormwater, or surface water, to name some non-exclusive examples among others. It should be noted that contaminants in addition to the organic contaminants can be present in the aqueous liquid treated by the present process. For example, other contaminants include suspended materials such as metals (e.g. iron), and ions (e.g. chloride ions, and perchlorate ions, among others).

[0029] Referring to the drawings and more particularly to Fig. 1, there is illustrated a system 10 for treating an aqueous liquid including organic contaminants and perchlorate or an aqueous liquid in which perchlorate is formed during its treatment, in accordance with the present disclosure. The organic contaminants can for example be PFAS as explained above. For simplicity, reference is made herein to the system 10. In accordance with a variant of the present disclosure, the system 10 may have one or more of the following components, as some of the components may be optional: a transfer reservoir 20, one or more reactors 30 such as electro-oxidation (EO) reactors, an acid source 40, a hydrogen peroxide source 50, a cooling system 60, an activated carbon (AC) filter unit 70, a filter unit 80 and / or a controller 90. Other components may be present, such as valves, pump(s), sensors (e.g., pressure, temperature, electrical conductivity, pH), and have been omitted from Fig. 1 for simplicity and clarity. In a variant, the transfer reservoir 20 and the reactor(s) 30 are arranged in a recirculation loop A, with the aqueous liquid flowing in the recirculation loop during part of the process. In the recirculation loop A, the acid source 40, the hydrogen peroxide source 50, the cooling system 60 may play an active role to condition the aqueous liquid for the process.

[0030] The transfer reservoir 20 receives an aqueous liquid in which organic contaminants and perchlorate will be treated or destroyed. The transfer reservoir 20 acts as a buffer to contain the aqueous liquid while it is treated for a sufficient time by the reactors 30. The treatment is performed in order to reach a condition in which theorganic contaminants and perchlorate can be adsorbed by the AC and are thus safe to exit the recirculation loop toward the AC filter unit 70, to then be output from the system 10. While the expression “reservoir” is used for transfer reservoir 20, other expressions could be used such as tank, basin, receiver, holder, etc.

[0031] The one or more reactors 30 can be chemical reactors adapted to degrade or destroy the organic contaminants. In some embodiments, when the organic contaminants are or include PFAS, the one or more reactors are one or more electrooxidation (EC) reactors 30 to degrade the PFAS. As an example, the EC reactor(s) 30 may include boron-doped diamond electrode(s), but other electrodes are possible.

[0032] The transfer reservoir 20 and the one or more reactors 30 may be part of the recirculation loop A featuring one or more conduits A1 by which the aqueous liquid flows between the transfer reservoir 20 and the reactor(s) 30. The conduit(s) A1 may thus fluidly connect the transfer reservoir 20, the one or more reactors 30, the acid source 40, and the hydrogen peroxide source 50 in any appropriate manner.

[0033] The acid source 40 is in fluid communication with the recirculation loop A for adding an acid into the aqueous liquid. The acid source 40 may be in the form of an apparatus, device, conduit network, and may be provided with the various components to measure a dose of acid that is added to the aqueous liquid. The acid source 40 may be connected to any component of the recirculation loop A, or may be upstream of the recirculation loop A. In at least some embodiments, the acid is provided such that the aqueous liquid maintains a pH in the range of up to 5, for example from 4 to 5, inclusively, at the start of the process. During the process the pH can be in the range of from 3 to 5 inclusively, for example, around 3.5. This pH range enhances and enables the scavenging of the chlorine by the hydrogen peroxide which in turn reduces, or in some embodiments prevents, the formation of perchlorate by electro-oxidation of the chlorine. Although different acid choices are possible, preferred acids include and are not limited to sulfuric acid, citric acid, and phosphoric acid.

[0034] In a variant, the acid source 40 includes an acid dosing system that may have a storage tank with its accessories, a metering pump and its accessories. The storage tank may be a barrel to be replaced by a new barrel when the acid is depleted. Acidmust be added quickly to the water before the electro-oxidation reaction begins. An exemplary dosing rate is 20 mL / min (estimated range between 20 and 80 mL / min, inclusively). The pump may operate until the desired pH is reached.

[0035] The hydrogen peroxide source 50 is in fluid communication with the recirculation loop A for adding hydrogen peroxide to the aqueous liquid. The hydrogen peroxide source 50 may be in the form of an apparatus, device, conduit network, and may be provided with the various components to measure and control a dose of hydrogen peroxide that is added to the aqueous liquid. The hydrogen peroxide source 50 may be connected to any component of the recirculation loop A, or may be upstream of the recirculation loop A. In at least some embodiments, the hydrogen peroxide source 50 provides and maintains a concentration of hydrogen peroxide in the reactor in the range from 50 to 200 mM, inclusively. This range is particularly advantageous when the aqueous liquid contains chloride, because it helps to reduce and / or prevent the electro-oxidation formation of chlorine from chloride and consequently reduce or, in some embodiments, prevent the formation of perchlorate.

[0036] The cooling system 60 may be in a heat exchange relation with the recirculation loop A, in order to control a temperature of the aqueous liquid in the recirculation loop A. The cooling system 60 may be in heat exchange relation with one or more of the transfer reservoirs 20, the reactor(s) 30, the conduit(s) A1. The cooling system 60 may take various forms, such as a heat pump, liquid-liquid heat exchanger or liquid-air heat exchanger and a refrigeration system. For example, the cooling system 60 may include a coolant or refrigerant circulating in a coil(s) that is in heat exchange relation with the aqueous liquid. The cooling system 60 may use any available cold source (e.g. , outdoor air, body of water, etc.) to reclaim and / or generate cold that will be used to regulate a temperature of the aqueous liquid in accordance with the parameters of the system 10 and / or a process of the present disclosure. In one example, the cooling system 60 includes an air-liquid heat exchanger. In an embodiment, the cooling system maintains the temperature in the recirculation loop and in the reactor in the range of between 30 and 65°C inclusively or preferably from 40 to 65 °C inclusively.

[0037] The activated carbon (AC) filter unit 70 may be provided downstream of the recirculation loop A. The AC filter unit 70 may therefore treat the aqueous liquid exitingthe recirculation loop A, as the aqueous liquid exiting the recirculation loop A may be in a desired condition to be treated. The AC filter unit 70 may take any appropriate configuration, such as one or more granular activated carbon adsorption filters, for adsorbing the degraded residual PFAS and perchlorate. It should be noted that traditionally, activated carbon such as granular activated carbon may not suitably adsorb perchlorates. The residual hydrogen peroxide in the aqueous liquid as well as the elevated temperature, presence of other oxidants, and acidic pH, together, may further activate and / or clean the adsorption surface sites of the activated carbon, resulting in an improvement to its adsorption capacity.

[0038] When considering embodiments where the organic contaminants include PFAS, the present process significantly reduces the formation of perchlorates during the EO treatment of the aqueous liquid and then successfully removes residual PFAS and perchlorate to undetectable or negligible levels using the activated carbon filtration. One advantage of the present process is that the filtration with activated carbon can be achieved with a short residence time such as by using an empty bed contact time (EBCT) of the order of 15 minutes or less. The synergistic combinations of the present EO and GAO process may improve the applicability of PFAS destruction in water using electro-oxidation when chloride ions are present. In some embodiments, the perchlorate formation is reduced by 60-97% by adding H2O2 to scavenge chlorine. The characteristics of the EO treated water with a temperature of 35-65 °C, a pH of 3-4, presence of residual perchlorate, H2O2, H2 and oxidants, allows for the improved adsorption of perchlorate by the activated carbon filter, that can reach undetectable or negligible levels.

[0039] As mentioned before, the present process can be used to destroy PFAS and reduce or prevent electro-oxidation production of perchlorate if chloride ions are present in water. Chloride ions are frequently present in PFAS contaminated waters, such as groundwater, industrial water, leachate, aqueous film forming foam (AFFF) water, ion exchange reject stream and reverse osmosis reject stream to name a few. The present process is therefore a simple, cost effective, rapid and efficient process to remove perchlorate to undetectable or negligible concentrations in PFAS contaminated water treated by electro-oxidation. Accordingly, a better quality of treated water is obtained with the present process. That treated water can be safely evacuated in the environment, to the sewer or reused in industrial or other processes.

[0040] More generally, whether the reactor is an EO reactor or not, the low pH preserves the positively charged surface of the bituminous-pHZpc >8 activated carbon to which perchlorate anions are attracted to through electrostatic forces. In addition, hydrogen peroxide, as well as the potential presence of ozone and other oxidants like O2, CI2, CIO; CIO2, S2O82; MnO4-, C^O? and / or H2SO4, at moderate temperatures, may increase the presence of the acidic, but also basic oxygen-bearing functional groups (carboxyl, ketone and ether) on the media surface resulting in an apparent and unexpected enhancement of perchlorate anions removal. This enhancement may be explained by direct interaction of the perchlorate anion with the carbon surface or by bounding H+ions that will ultimately attract the anion. Acidic conditions issued from the electro-oxidation process (potential presence of HCI, HF, etc.) may also facilitate the availability of adsorption sites on the media surface through various mechanisms, such as demineralization.

[0041] The aqueous liquid fed to the recirculation loop A may have been treated and / conditioned to be supplied to the recirculation loop A. The filter unit 80 is an example of a device among others that may be provided upstream of the transfer reservoir 20. For example, the filter unit 80 may be used to remove suspended solids from the aqueous liquid ahead of the recirculation loop A. The process operated by the system 10 may start with a preliminary microfiltration of particles over 5 pm to prevent fouling the electrodes surface. It is preferred that suspended solids are removed before the aqueous liquid enters the recirculation loop A or the transfer reservoir 20.

[0042] The controller 90 may have one or more processing unit 91, and a non-transitory computer-readable memory 92 communicatively coupled to the processing unit 91 and comprising computer-readable program instructions executable by the processing unit for operating the system 10 in accordance with a process for treating an aqueous liquid including perfluoroalkyl and polyfluoroalkyl substances (PFAS) and perchlorate. Accordingly, the controller 90 may actuate and control a pump(s), valve(s), the dosing and injection of the acid and / or hydrogen peroxide, etc.

[0043] Now that various components of the system 10 have been described, a process 100 for treating an aqueous liquid including perfluoroalkyl and polyfluoroalkyl substances (PFAS) and perchlorate is set out, with reference to Fig. 2. The process100 may or may not be performed with the system 10. The process 100 may be driven in an embodiment by the controller 90.

[0044] According to step 101, an aqueous liquid is received, such as in a loop, receiver, reservoir, to be conditioned and treated. For example, the aqueous liquid including organic contaminants (e.g., perfluoroalkyl and polyfluoroalkyl substances (PFAS)) and perchlorate. Step 101 may optionally include filtering solids in suspension from the aqueous liquid. Stated differently, the aqueous liquid may be filtered in step 101 to separate out suspended solid contaminants before degrading the PFAS from the aqueous liquid.

[0045] According to step 102, hydrogen peroxide is added to the aqueous liquid. Step 102 may include monitoring the aqueous liquid to determine that a suitable amount of hydrogen peroxide has been added. Step 102 may include dosing and injecting the hydrogen peroxide in the aqueous liquid. For example, the hydrogen peroxide is injected in the aqueous phase at a concentration of from 50 to 200 mM, although other ranges are possible.

[0046] According to step 103, the aqueous liquid is acidified to maintain an acidic pH of 5 or less. As an example, step 103 includes adding H2SO4 as one possible type of acid among others.

[0047] According to optional step 104, the aqueous liquid is cooled to remain within a desired temperature range. This may for example include maintaining a temperature of the aqueous liquid between 35 and 65°C inclusively, or 40 and 60°C inclusively, although other ranges are possible.

[0048] According to optional step 105, the organic contaminants in the aqueous liquid are degraded in a reactor in the aqueous liquid to obtain residual organic contaminants. In embodiments where the organic contaminants are PFAS, the PFAS are degraded in an EO reactor by an electro-oxidation process.

[0049] Steps 102, 103, 104 and 105 may occur intermittently, in any appropriate order. For example, steps 102, 103, 104 and 105 are performed as part of a batch process, i.e. , a relatively fixed volume of aqueous liquid that is treated or conditioned to then move on to the next step(s) of the process 100. Steps 102, 103, 104 and 105may be performed as part of a recirculation loop, in which the aqueous liquid goes through some of the steps 102, 103, 104 and / or 105 in any appropriate sequence. Some of the steps such as step 104 and 105 may be optional (independently).

[0050] According to step 106, upon completion of the residence in a loop in which at least some of the steps 102, 103, 104 and 105 are performed, the aqueous liquid is exposed to activated carbon, for the activated carbon to adsorb the residual organic contaminants and residual perchlorate from the aqueous liquid.

[0051] According to step 107, the liquid may be output from the process 100.

[0052] Referring concurrently to Figs. 3-6, a schematic diagram of an exemplary configuration of the system 10 for treating an aqueous liquid is illustrated, as an example of a possible configuration. Fig. 3 is a legend explaining the symbols found in the schematic diagram of Figs. 4-6. It bears mentioning that the system 10 is shown cumulatively by Figs. 4, 5 and 6, to provide sufficient space for the symbols to be legible. All the components of the system 10 may be assembled in a container, as an option. The container may be a standard 20 ft container, as an option. The container may be insulated, ventilated by a fan installed in the container and via a louver-type fresh air inlet, again optionally. A thermometer is installed in the container. The air temperature in the container must be maintained above a given threshold (e.g., 10°C) to prevent water from freezing in the pipes and system equipment that could cause them to break. A hydrogen detector may be installed on the ceiling of the container, with appropriate fans to dilute and remove the hydrogen, if levels are excessive.

[0053] In Fig. 4, the hydrogen peroxide source 50 is shown as including a reservoir or like tank and a dosing system.

[0054] In Fig. 5, the reactors 30 are shown as being a series of EO reactors 30 in parallel to one another, as one possible configuration.

[0055] In Fig. 6, there are four different columns of activated carbon filters 70, as one possible configuration. A combination of parallel and series arrangement is used for the AC filters 70. A tank is shown as being upstream of the AC filters 70 and is present, to serve as a buffer as a function of the capacity of the AC filters 70. However, as previously explained, the tank can optionally be a loop, receiver, or reservoir. Theacid source can be in fluid communication with the tank or can be provided upstream of the tank in order to acidify the aqueous liquid as explained above.

[0056] EXAMPLE

[0057] A non-limitative example is given to illustrate parameters of a process, such as the process 100 of Fig. 2, performed in a system, such as the system, 10 of Fig. 1. Contaminated water was pumped at 20 liters per minute using a submersible pump. The contaminated water was filtered with a microfilter of 5 pm to prevent suspended solids from entering the transfer reservoir. The filter was a nylon membrane capable of filtering suspended solids. This filtration step also removed the iron in suspension in the water. Iron could interfere with the reaction between hydrogen peroxide and chloride, thus its elimination is preferred. As explained above, the water circulates between the transfer reservoir and EO reactors. The recirculation pump had a flow of about 200 liters per minute. In this recirculation loop, an air-liquid heat exchanger was installed to maintain the temperature in the range of from 50 to 55 °C. During recirculation, hydrogen peroxide was dosed into the water by a pump. As explained above, the role of the hydrogen peroxide is to prevent the formation of chlorine and by extension perchlorate. The hydrogen peroxide is stored in a storage reservoir and provided into the system with a dosage pump. A minimum concentration of 50 mM of hydrogen peroxide was maintained. Sulfuric acid was the choice of acid used to set the initial pH in the range of from 4.4 to 4.6. The acidic pH promotes the reaction between hydrogen peroxide and chlorine. The sulfuric acid was stored in a designated reservoir and was provided through a dosage pump with the target pH to maintain being 4.5 at the start of the process and 3.5 during the process. The dosage pump provided 20-80 mL / min of sulfuric acid solution. Once the treatment of the water is completed, the output of the recirculation loop was pumped to a second transfer reservoir and then was pumped into adsorption columns containing activated carbon. This filtration step adsorbed the residual organic contaminants in the water and in particular the present process achieves an improved removal of perchlorate.

[0058] To monitor the pH, the temperature, the conductivity and the hydrogen concentration, suitable probes were incorporated into the system. Probes were also used to monitor the level of water in the transfer reservoirs. The various devices of the system were all connected to a controller for easier operation of the system.

[0059] The EO reactors were operated with a DC current (minimum 30A, maximal power 10 kW (63A / 160V). The electrodes in the EO reactors were boron doped diamond electrodes. Out of the 200 LPM flow in the recirculation loop, 100 LPM went to each of the two EO reactors as they were hydraulically parallel.

[0060] A dosage pump took the water from the second transfer reservoir into the adsorption column at a flow rate of 4.5 LPM. Specifically, two columns of activated carbon were used in series or in parallel to capture perchlorate and adsorb PFAS residual in the water. The objective to reach a level of 10 ppb of perchlorate and few ppb of PFAS or less was achieved. The residence time in each column was 11.4 minutes.

[0061] Table 1 shows that if the pH is not reduced or if H2O2is not added, the perchlorate formation cannot be prevented. Table 1 is merely provided as an example based on specific conditions.Table 1. EO assay results

[0062] Specifically, sample IDs 1, 3, 9 and 11 show that when there is no concomitant pH adjustment (to lower values) and hydrogen peroxide addition, the resulting concentrations of perchlorate are the highest in all four samples.

[0063] The remaining examples show that perchlorate concentrations are decreased when operating at low pH and in the presence of hydrogen peroxide. Samples IDs 12, 13, and 14 suggest that there is an optimal pH value when in acidic conditions.

[0064] In the present process, perchlorate removal by the granular activated carbon (GAC) media was made possible when the pH was reduced to 3-4. GAC performance was enhanced when there was residual H2O2 as illustrated in the water treatment results in Table 2. Table 2 is merely provided as an example based on specific conditions.Table 2. Effect of residual H2O2

[0065] No EO ttm = No EO treatment; and demin water = demineralized water

[0066] The above description is meant to be exemplary only, and one skilled in the art will recognize that changes may be made to the embodiments described without departing from the scope of the invention disclosed. Still other modifications which fall within the scope of the present invention will be apparent to those skilled in the art, inlight of a review of this disclosure, and such modifications are intended to fall within the appended claims.

Claims

CLAIMS1. A process of treating an aqueous liquid, the process comprising:receiving the aqueous liquid including organic contaminants and chloride;adding hydrogen peroxide to the aqueous liquid;acidifying the aqueous liquid to maintain an acidic pH of up to 5; degrading the organic contaminants in a reactor to obtain residual organic contaminants while perchlorate is formed; and adsorbing the residual organic contaminants and perchlorate from the aqueous liquid by exposing the aqueous liquid to activated carbon.

2. The process of claim 1, wherein receiving the aqueous liquid including the organic contaminants includes receiving the aqueous liquid including perfluoroalkyl and polyfluoroalkyl substances (PFAS).

3. The process of claim 1 or 2, wherein degrading the organic contaminants in the reactor includes degrading the organic contaminants in an electro-oxidation reactor.

4. The process of claim 3, wherein degrading the organic contaminants in the electro-oxidation reactor includes degrading the organic contaminants with one or more of boron-doped diamond electrodes.

5. The process of any one of claims 1 to 4, further comprising filtering the aqueous liquid to separate out suspended solids before degrading the organic contaminants.

6. The process of any one of claims 1 to 5, further comprising maintaining a temperature of the aqueous liquid between 35 and 65°C, inclusively.

7. The process of any one of claims 1 to 6, wherein the step of adding the hydrogen peroxide to the aqueous liquid includes maintaining the hydrogen peroxide in the aqueous phase at a concentration of from 50 to 200 mM.

8. The process of any one of claims 1 to 7, wherein the step of acidifying comprises adding H2SO4.

9. The process of any one of claims 1 to 8, including the steps of adding, acidifying and degrading are performed in a recirculation loop.

10. The process of claim 10, including pumping the aqueous liquid for performing the recirculation loop.

11. The process of claim 9 or claim 10, including cooling the aqueous liquid in the recirculation loop.

12. A system for treating an aqueous liquid, the system comprising:a recirculation loop including:a transfer reservoir for receiving the aqueous liquid including organic contaminants and chloride,one or more reactors for degrading the organic contaminants in the aqueous liquid to obtain residual organic contaminants and in which perchlorate is produced, an acid source in fluid communication with the recirculation loop for adding an acid into the aqueous liquid,a hydrogen peroxide source in fluid communication with the recirculation loop for adding hydrogen peroxide to the aqueous liquid, andat least one conduit for fluidly connecting the transfer reservoir, the one or more reactors; andone or more activated carbon adsorption filters downstream of the recirculation loop for adsorbing the residual organic contaminants and perchlorate.

13. The system of claim 12, further comprising a filter upstream of the recirculation loop to remove suspended solids from the aqueous liquid.

14. The system of claim 12 or 13, wherein the recirculation loop further comprises a cooling system for cooling the aqueous liquid.

15. The system of any one of claims 12 to 14, wherein the conduit includes a recirculation pump to recirculate the aqueous liquid between the reservoir and the one or more reactors.

16. The system of any one of claims 12 to 15, wherein the organic contaminants include perfluoroalkyl and polyfluoroalkyl substances (PFAS).

17. The system of any one of claims 12 to 16, wherein the reactor is an electrooxidation reactor.

18. The system of claim 17, wherein the electro-oxidation reactor includes one or more boron-doped diamond electrodes.

19. The system according to any one of claims 12 to 18, further including a controlling having one or more processing unit, and a non-transitory computer-readable memory communicatively coupled to the processing unit and comprising computer-readable program instructions executable by the processing unit for controlling an addition of the acid into the aqueous liquid, and controlling an addition of the hydrogen peroxide in the aqueous liquid.

20. The system according to claim 19, wherein the computer-readable program instructions are further executable by the processing unit for controlling a flow of the aqueous liquid in the recirculation loop and for outletting part of the aqueous liquid toward the adsorbing.

Images