Cleaning method and cleaning system for judging microbial contamination of electrodeionization module

Abstract

The invention discloses a cleaning method and a cleaning system for judging microbial contamination of an electrodeionization module. The cleaning method comprises the following steps: judging and confirming that the electrodeionization module is microbial contamination; after the resin transformation solution is used for circular treatment, desalted water is used for back flushing; a mixed solution of an alkaline solution and a complexing agent is adopted for circular treatment; and after soaking treatment by adopting a non-oxidizing bactericide, forward and reverse flushing is performed by utilizing demineralized water. The three methods of resin transformation, chemical cleaning and physical flushing are adopted, so that the resin volume is reduced by about 15%, and the flushing efficiency is improved; under the synergistic effect of the complexing agent and the alkaline solution, the removal rate of the biological membrane reaches 90% or above; a double-insurance anti-oxidation design is adopted, on one hand, the oxidation-reduction potential of cleaning liquid is smaller than 100 mV through dynamic adsorption of activated carbon, on the other hand, a non-oxidizing bactericide is used for replacing a traditional chlorine-containing agent, the module is protected against damage, and the service life of the module is prolonged.

Description

Technical Field

[0001] This invention relates to the field of electrostatic desalination module technology, and in particular to a method and system for judging and cleaning microbial contamination of electrostatic desalination modules. Background Technology

[0002] Electrodialysis (EDI) is a deep desalination technology that combines electrodialysis and ion exchange resins, and is widely used in the production of high-purity water in industries such as electronics, pharmaceuticals, and power. Compared with traditional ion exchange technology, EDI has the advantages of continuous operation without the need for acid and alkali regeneration; stable production of ultrapure water with a resistivity of 15-18 MΩ·cm; small footprint and high degree of automation; compact equipment structure and easy integration with automated control. However, its membrane block has a narrow internal cavity, and pollutants (especially microorganisms and their metabolites) are easy to accumulate in the flow channel, resin gaps and membrane surface. Traditional cleaning methods have the following disadvantages: (1) Incomplete cleaning: biofilm has strong adhesion and is difficult to remove with conventional rinsing; (2) Oxidation risk: chlorine in the cleaning agent will oxidize the ion exchange membrane, causing irreversible damage; (3) Untimely pollution detection, delaying treatment. Summary of the Invention

[0003] The present invention aims to at least partially solve one of the technical problems in the related art.

[0004] Therefore, embodiments of the present invention propose a method and system for judging and cleaning microbial contamination of an electrostatic desalination module.

[0005] In a first aspect, the present invention proposes a method for judging and cleaning microbial contamination in an electrostatic desalination module, comprising the following steps:

[0006] (1) It was determined that the electro-desalination module was contaminated with microorganisms;

[0007] (2) After the resin conversion solution is circulated, it is backwashed with demineralized water.

[0008] (3) A mixed solution of alkaline solution and complexing agent is used for cyclic treatment;

[0009] (4) After soaking in a non-oxidizing bactericide, rinse with deionized water in both directions.

[0010] Furthermore, the process also includes treating the resin conversion solution, the demineralized water, and the mixture of the alkaline solution and the complexing agent through an activated carbon bed before they enter the electro-demineralization module.

[0011] Furthermore, the determination and confirmation that the electro-desalination module is contaminated with microorganisms includes:

[0012] Determine if the resistivity of the produced water decreases by ≥30%. If not, proceed with normal operation. If so, determine if the operating voltage increases by ≥20%.

[0013] If the working voltage rises by less than 20%, then process the incoming water; if the working voltage rises by ≥20%, then determine whether the pressure difference rise is ≥0.1MPa.

[0014] If the pressure difference rises by less than 0.1 MPa, treat the incoming water; if the pressure difference rises by ≥0.1 MPa, check if there is any odor or discoloration at the outlet of the electro-deionization module.

[0015] If there is an odor or discoloration at the outlet of the electro-desalination module, it is confirmed to be microbial contamination; if there is no odor or discoloration at the outlet of the electro-desalination module, the incoming water is treated.

[0016] Furthermore, the mass concentration of the resin conversion solution is 2% to 4%.

[0017] Furthermore, the resin conversion solution includes one or both of sodium chloride solution and potassium chloride solution.

[0018] Furthermore, in step (2), the backwashing with demineralized water is performed by backwashing with demineralized water at a flow rate of 3 to 4 times the design flow rate for 30 to 60 minutes.

[0019] Further, the mass concentration of the alkaline solution is 0.1% to 0.2%, and the mass concentration of the complexing agent is 1% to 2%.

[0020] Furthermore, the complexing agent includes one or both of EDTA solution and disodium ethylenediaminetetraacetate.

[0021] Furthermore, the cyclic treatment in step (3) is to cycle at 40-45°C for 2-3 hours.

[0022] Furthermore, the non-oxidizing bactericide includes quaternary ammonium salt bactericides or isothiazolinone bactericides.

[0023] Secondly, the present invention proposes an electrostatic desalination module microbial contamination cleaning system, applicable to the cleaning method proposed in the first aspect, comprising a reagent tank, a cleaning pump, a flow meter, an activated carbon bed, and an ORP meter arranged sequentially upstream and downstream. The reagent tank is used to hold the reagent passing through the electrostatic desalination module; the cleaning pump is used to pump the reagent; the flow meter is used to measure the flow rate of the reagent; the activated carbon bed is used to adsorb oxidizing substances in the reagent; and the ORP meter is used to measure the redox potential of the reagent flowing out from the activated carbon bed.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] This invention employs three methods—resin transformation, chemical cleaning, and physical rinsing—to reduce resin volume by approximately 15% and improve rinsing efficiency. By utilizing the synergistic effect of complexing agents and alkaline solutions, the removal rate of biofilm reaches over 90%.

[0026] This invention employs a "double insurance" anti-oxidation design. On the one hand, it utilizes the dynamic adsorption of activated carbon to keep the oxidation-reduction potential of the cleaning solution below 100mV. On the other hand, it replaces traditional chlorine-containing agents with non-oxidizing bactericides to protect the module from damage and extend its service life.

[0027] This invention uses a multi-parameter linkage method based on resistivity decrease, working voltage increase, voltage difference increase, and odor and color change to accurately distinguish between microbial contamination and other types of contamination, including scaling, organic contamination, etc. Attached Figure Description

[0028] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0029] Figure 1 This is a flowchart of the microbial contamination judgment and cleaning method for the electrostatic desalination module of the present invention;

[0030] Figure 2 This is a process diagram illustrating how the electro-desalination module was identified as being contaminated with microorganisms in this invention.

[0031] Figure 3 This is a schematic diagram of the microbial contamination cleaning system of the electro-desalination module of the present invention. Detailed Implementation

[0032] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0033] The following description, in conjunction with the accompanying drawings, describes the microbial contamination judgment and cleaning method and cleaning system for the electro-desalination module proposed in this invention.

[0034] like Figure 1 As shown, the microbial contamination judgment and cleaning method for the electro-desalination module of the present invention includes the following steps:

[0035] (1) It was determined that the electro-desalination module was contaminated with microorganisms;

[0036] (2) After the resin conversion solution is circulated, it is backwashed with demineralized water.

[0037] (3) A mixed solution of alkaline solution and complexing agent is used for cyclic treatment;

[0038] (4) After soaking in a non-oxidizing bactericide, rinse with deionized water in both directions.

[0039] Among them, such as Figure 2 As shown, the determination and confirmation of microbial contamination of the electro-desalination module in step (1) includes:

[0040] (a) Determine if the resistivity of the produced water decreases by ≥30%. If not, proceed with normal operation. If so, determine if the operating voltage increases by ≥20%.

[0041] (b) If the working voltage rises by less than 20%, then treat the incoming water; if the working voltage rises by ≥20%, then determine whether the pressure difference rise is ≥0.1MPa.

[0042] (c) If the pressure difference rises by less than 0.1 MPa, treat the incoming water; if the pressure difference rises by ≥0.1 MPa, check if there is any odor or discoloration at the outlet of the electro-deionization module.

[0043] (d) If there is an odor or discoloration at the outlet of the electro-desalination module, it is confirmed as microbial contamination; if there is no odor or discoloration at the outlet of the electro-desalination module, the incoming water is treated.

[0044] In step (a), after the detection begins, the resistivity of the produced water is first measured to determine if the decrease in resistivity is ≥30%. If yes, the operating voltage of the electro-desalination module is then measured; otherwise, normal operation continues. When there is microbial contamination, the organic acids and polysaccharides produced by microbial metabolism increase ion leakage, causing a decrease in the resistivity of the produced water. Therefore, the resistivity of the produced water is measured first. The rate of decrease in resistivity is the ratio of the current resistivity to the initial resistivity of the electro-desalination module. The operating voltage is the operating voltage of the electro-desalination module, which can be understood as being displayed in real time.

[0045] In step (b), when the resistivity of the produced water decreases by ≥30%, it is determined whether the working voltage increases by ≥20%. If the working voltage increases by less than 20%, it may indicate that the incoming water has high conductivity, and the incoming water should be treated to reduce its conductivity. If the working voltage increases by ≥20%, subsequent differential pressure assessment is performed. It is understandable that when a biofilm generated by microbial contamination covers the ion exchange membrane, it hinders ion migration, causing an increase in working voltage. Therefore, working voltage can be used as a criterion for determining whether there is microbial contamination.

[0046] In step (c), when the operating voltage increases by ≥20%, it is determined whether the pressure difference increase is ≥0.1MPa. If the pressure difference increase is less than 0.1MPa, it may indicate high conductivity of the incoming water. In this case, the incoming water is treated to reduce its conductivity. If the pressure difference increase is ≥0.1MPa, subsequent checks are performed to determine if there is an odor or discoloration at the outlet of the electro-desalination module. Here, pressure difference refers to the difference between the pressure of the water entering and leaving the electro-desalination module. It is understandable that when microbial contamination occurs, the flow channels or resin gaps of the electro-desalination module become blocked by biofilm, causing a rise in pressure difference. Therefore, pressure difference can be used as a criterion for determining whether microbial contamination has occurred.

[0047] In step (d), when the pressure difference increases by ≥0.1 MPa, check whether there is any odor or discoloration at the outlet of the electro-desalination module. If there is no odor or discoloration at the outlet, it may be due to high conductivity of the incoming water. In this case, treat the incoming water to reduce its conductivity. If there is an odor or discoloration at the outlet, it is confirmed as microbial contamination. It is understandable that when microbial contamination occurs, the outlet of the electro-desalination module will produce odorous gases such as hydrogen sulfide or the water will become turbid and discolored. Therefore, whether there is an odor or discoloration at the outlet of the electro-desalination module can be used as a basis for judging whether there is microbial contamination.

[0048] This invention uses a multi-parameter linkage method based on resistivity decrease, working voltage increase, voltage difference increase, and odor and color change to accurately distinguish between microbial contamination and other types of contamination, including scaling, organic contamination, etc.

[0049] Step (2) is the resin transformation and high-flow-rate rinsing process. After the resin transformation solution is circulated, it is backwashed using demineralized water. The backwashing is a rinsing method in which water flows in from the outlet of the EDI module and flows out from the inlet.

[0050] In some embodiments, the mass concentration of the resin conversion solution is 2% to 4%, and the resin conversion solution includes one or both of sodium chloride solution and potassium chloride solution. When sodium chloride solution is used as the conversion solution, the sodium chloride solution is passed into the electro-desalination module to make the hydrogen-form cation resin (H... + -R) is converted to the sodium form (Na) + -R), hydroxyl anion exchange resin (OH) - -R) is converted to the chlorine form (Cl) - -R) reduces the resin volume by 10% to 15%, loosens the resin in the membrane cavity, and thus creates channels within the resin.

[0051] In some embodiments, the resin conversion solution is rinsed by circulating at 1.5 to 2 times the design flow rate for 1 to 2 hours.

[0052] In some embodiments, backwashing with demineralized water involves backwashing with demineralized water at a flow rate of 3 to 4 times the design flow rate for 30 to 60 minutes, i.e., using a high flow rate of demineralized water to flush out detached biofilm fragments and particulate matter. It is understood that the design flow rate refers to the design flow rate of the electro-desalination module.

[0053] Step (3) is an alkaline washing cycle process, which is a chemical cleaning process that uses a mixed solution of alkaline solution and complexing agent for cyclic treatment.

[0054] In some embodiments, the mass concentration of the alkaline solution is 0.1% to 0.2%, and the mass concentration of the complexing agent is 1% to 2%.

[0055] In some embodiments, the alkaline solution includes one or both of sodium hydroxide solution and potassium hydroxide. In some embodiments, the complexing agent includes one or both of EDTA solution and disodium ethylenediaminetetraacetate. The alkaline solution is used for organic matter, and the complexing agent is used to complex divalent metal ions, such as Ca2+, in biological membranes. 2+ Mg 2+ This enhances the biofilm removal effect. The alkaline solution and complexing agent work synergistically to wash away the biofilm.

[0056] In addition, it is understandable that the mixing ratio of alkaline solution and complexing agent can be adjusted according to specific working conditions.

[0057] In some embodiments, the alkaline washing cycle is performed at 40–45°C for 2–3 hours.

[0058] Step (4) involves soaking in a non-oxidizing bactericide and rinsing with desalinated water. After the alkaline washing cycle is completed, a quaternary ammonium salt bactericide or isothiazolinone bactericide with a concentration of 50-100 ppm is selected, and the circulation system is closed for static soaking for 6-10 hours to completely kill residual microorganisms. Then, desalinated water is used for alternating forward and reverse rinsing until the effluent conductivity is <1 μS / cm and the pH is neutral (7±0.5) to ensure no drug residue.

[0059] The process of soaking with a non-oxidizing bactericide in step (4) is a chemical cleaning process, while the demineralized water rinsing process in step (4) and the demineralized water rinsing process in step (2) are physical rinsing processes.

[0060] In some embodiments, before entering the electro-desalination module, the resin conversion solution, the desalinated water, and the mixture of the alkaline solution and the complexing agent are all treated with an activated carbon bed. That is, all the cleaning liquid is passed through an activated carbon bed (particle size 1-3 mm, contact time ≥30 s) to adsorb oxidizing chloride ions such as chlorate and hypochlorite, as well as other oxidizing substances (such as ozone and peroxides), ensuring that the oxidation-reduction potential (ORP) of the cleaning liquid is <100 mV.

[0061] It is understandable that the resin membrane of the electro-deionization module has active groups. Oxidizing substances will oxidize the active groups, thereby causing membrane damage. Therefore, before all the cleaning liquid enters the electro-deionization module, the oxidizing substances are removed by the activated carbon bed. In step (4), a non-oxidizing bactericide is used in the sterilization process to protect the integrity of the EDI membrane and avoid damage.

[0062] This invention employs three methods—resin transformation, chemical cleaning, and physical rinsing—to reduce resin volume by approximately 15% and improve rinsing efficiency. By utilizing the synergistic effect of complexing agents and alkaline solutions, the removal rate of biofilm reaches over 90%.

[0063] This invention employs a "double insurance" anti-oxidation design. On the one hand, it utilizes the dynamic adsorption of activated carbon to keep the oxidation-reduction potential of the cleaning solution below 100mV. On the other hand, it replaces traditional chlorine-containing agents with non-oxidizing bactericides to protect the module from damage and extend its service life.

[0064] like Figure 3 As shown, the electrostatic desalination module microbial contamination cleaning system of the present invention includes a reagent tank, a cleaning pump, a flow meter, an activated carbon bed, and an ORP meter arranged sequentially upstream and downstream. The reagent tank is used to hold the reagents passing through the electrostatic desalination module. The reagents include a resin conversion solution, the desalinated water, a mixed solution of the alkaline solution and a complexing agent. The cleaning pump is used to pump the reagents. The flow meter is used to measure the flow rate of the reagents. The activated carbon bed is used to adsorb oxidizing substances in the reagents. The ORP meter is used to measure the redox potential of the reagents flowing out of the activated carbon bed.

[0065] During operation, the reagent is pumped out by the cleaning pump and flows sequentially through the flow meter, activated carbon bed, and ORP meter before entering the EDI module. After rinsing the EDI module, the reagent flows back to the reagent tank through the return pipe, forming a cycle. During this process, the reagent is adsorbed and has oxidizing substances removed by the activated carbon in the activated carbon bed.

[0066] The present invention will now be described with reference to specific embodiments.

[0067] The initial resistivity of the EDI module system was 16 MΩ·cm. After working for a period of time, the resistivity of the produced water was measured to be 4 MΩ·cm, a decrease of 75% (>30%). Subsequent testing showed that the EDI operating voltage increased by 25% (>20%), the pressure difference increased by 0.12 MPa (>0.1 MPa), and there was an odor at the EDI module outlet, confirming that the EDI module produced water contaminated with microorganisms.

[0068] Cleaning was performed using the cleaning system of this invention. Before entering the EDI module, the cleaning solution was adsorbed and filtered through an activated carbon bed, reducing the ORP from 250 mV to 50 mV. A 3% sodium chloride solution was prepared and circulated at twice the design flow rate for 2 hours to allow the hydrogen-form cation exchange resin (H...) to... + -R) is converted to the sodium form (Na) + -R), hydroxyl anion exchange resin (OH) - -R) is converted to the chlorine form (Cl) - -R), then switch to demineralized water and backwash for 30 minutes at 4 times the design flow rate to flush out detached biofilm fragments and particulate matter. A mixture of 0.2% NaOH solution (pH 10-11) and 2% EDTA solution is circulated at 45°C for 2 hours, with equal volumes of NaOH and EDTA solutions mixed. A 50ppm quaternary ammonium salt bactericide is used, and the circulation system is shut off for static soaking for 6 hours to thoroughly kill residual microorganisms. Then, the system is rinsed alternately with demineralized water in both forward and reverse directions until the effluent conductivity is <1μS / cm and the pH is neutral (7±0.5), ensuring no chemical residue. This completes the cleaning process.

[0069] After cleaning, the resistivity of the EDI module's produced water recovered to 15.5 MΩ·cm, and the pressure difference dropped to the initial value of 0.03 MPa. It can be seen that the present invention has successfully cleaned the EDI module contaminated with microorganisms.

[0070] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms may refer to different embodiments or examples. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0071] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0072] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for judging and cleaning microbial contamination in an electrostatic desalination module, characterized in that, Includes the following steps: (1) It was determined that the electro-desalination module was contaminated with microorganisms; (2) After the resin conversion solution is circulated, it is backwashed with demineralized water. (3) A mixed solution of alkaline solution and complexing agent is used for cyclic treatment; (4) After soaking in a non-oxidizing bactericide, rinse with deionized water in both directions.

2. The method as described in claim 1, characterized in that, It also includes treating the resin conversion solution, the demineralized water, and the mixture of the alkaline solution and the complexing agent through an activated carbon bed before entering the electro-demineralization module.

3. The method as described in claim 1, characterized in that, The determination that the electro-desalination module is contaminated with microorganisms includes: Determine if the resistivity of the produced water decreases by ≥30%. If not, proceed with normal operation. If so, determine if the operating voltage increases by ≥20%. If the working voltage rises by less than 20%, then process the incoming water; if the working voltage rises by ≥20%, then determine whether the pressure difference rise is ≥0.1MPa. If the pressure difference rises by less than 0.1 MPa, treat the incoming water; if the pressure difference rises by ≥0.1 MPa, check if there is any odor or discoloration at the outlet of the electro-deionization module. If there is an odor or discoloration at the outlet of the electro-desalination module, it is confirmed to be microbial contamination; if there is no odor or discoloration at the outlet of the electro-desalination module, the incoming water is treated.

4. The method as described in claim 1, characterized in that, The mass concentration of the resin conversion solution is 2% to 4%.

5. The method as described in claim 1, characterized in that, The resin conversion solution includes one or both of sodium chloride solution and potassium chloride solution.

6. The method as described in claim 1, characterized in that, In step (2), the backwashing with demineralized water is performed by backwashing with demineralized water at a flow rate of 3 to 4 times the design flow rate for 30 to 60 minutes.

7. The method as described in claim 1, characterized in that, The alkaline solution has a mass concentration of 0.1% to 0.2%, and the complexing agent has a mass concentration of 1% to 2%.

8. The method as described in claim 1, characterized in that, The complexing agent includes one or both of EDTA solution and disodium ethylenediaminetetraacetate. And / or, the non-oxidizing bactericide includes quaternary ammonium salt bactericides or isothiazolinone bactericides.

9. The method as described in claim 1, characterized in that, The cyclic process in step (3) is to cycle at 40-45°C.

10. A microbial contamination cleaning system for an electro-desalination module, characterized in that, The method applicable to any one of claims 1 to 9 includes a reagent tank, a cleaning pump, a flow meter, an activated carbon bed, and an ORP meter arranged sequentially upstream and downstream, wherein the reagent tank is used to hold the reagent passing through the electro-desalination module, the cleaning pump is used to pump the reagent, the flow meter is used to measure the flow rate of the reagent, the activated carbon bed is used to adsorb oxidizing substances in the reagent, and the ORP meter is used to measure the redox potential of the reagent flowing out of the activated carbon bed.

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