A novel full-automatic reverse osmosis process and system integrating electrolysis technology

Abstract

The application relates to the technical field of water treatment, and discloses a novel full-automatic reverse osmosis process and system integrated with electrolysis technology. The process integrates electrolytic acid and alkali preparation, water inlet pH adjustment, product water pH adjustment, membrane chemical cleaning decision and waste liquid neutralization treatment into one body through a central control system to realize full-closed loop automatic control from raw material addition to waste liquid discharge without manual intervention. The PID algorithm is adopted to ensure the pH adjustment precision and the stability of electrolytic products. The automatic cleaning decision can avoid blind cleaning. The safety interlocking mechanism can effectively eliminate the hydrogen combustion and explosion risk. Meanwhile, the four-chamber electrolytic tank / double-pole membrane electrolytic tank can effectively avoid chlorine and hypochlorous acid generation, ensure the purity of acidic water, prevent membrane element oxidation damage, even if trace hypochlorous acid is generated, the oxidation risk can be further eliminated through a reduction and dosing device, and the safe operation of the membrane system is finally ensured.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, specifically to a novel fully automated reverse osmosis process and system integrating electrolysis technology. Background Technology

[0002] Reverse osmosis (RO) membrane systems have been widely used in fields such as seawater desalination and industrial water treatment. However, membrane systems still face a series of technical challenges in actual operation.

[0003] First, scale-forming ions such as calcium and magnesium in the feed water easily form inorganic scale such as calcium carbonate on the membrane surface, affecting membrane flux and permeate yield. Existing technologies typically rely on adding scale inhibitors or adjusting the feed water pH, but scale inhibitors are expensive, and some products are not environmentally friendly. Second, during membrane operation, organic matter, microorganisms, colloids, and other pollutants accumulate, requiring regular chemical cleaning. Traditional cleaning methods rely on purchasing concentrated acids and alkalis, which presents problems such as high storage risks, high transportation costs, and inconvenience in concentration control. Third, seawater desalination permeate is usually acidic, requiring pH adjustment to meet drinking water or subsequent process requirements. Traditional methods increase operating costs and the burden of chemical management by purchasing alkaline additives or mineralization processes. In addition, the acidic or alkaline wastewater generated from chemical cleaning will cause environmental pollution if discharged directly, requiring neutralization treatment to meet discharge standards. Traditional neutralization treatment requires the additional purchase of acid and alkali reagents, further increasing operating costs and operational management complexity.

[0004] Therefore, the industry urgently needs an integrated process that can solve the problems of membrane fouling, membrane fouling, permeate pH adjustment, and cleaning wastewater treatment in one integrated manner. Summary of the Invention

[0005] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a novel fully automated reverse osmosis process and system integrating electrolysis technology. It has the advantages of eliminating the need to purchase external acids, alkalis, and scale inhibitors, achieving in-situ cleaning and pH adjustment, simultaneous treatment of cleaning wastewater, reduced operating costs and environmental risks, and fully automated operation. It solves the problems of traditional reverse osmosis processes, such as membrane scaling relying on scale inhibitors, the need to purchase concentrated acids and alkalis for chemical cleaning posing storage and transportation risks, the need to add additional alkali for pH adjustment of permeate water, and the need for separate neutralization treatment of cleaning wastewater, which lead to complex chemical management, high operating costs, and environmental unfriendliness.

[0006] (II) Technical Solution To achieve the above objectives, the present invention provides the following technical solution: a novel fully automated reverse osmosis process integrating electrolysis technology, comprising the following steps: Step 1: Electrolysis to produce acid and alkali: Start the electrolytic cell, set the target current density, and electrolyze sodium chloride solution to prepare acidic and alkaline water. During the electrolysis process, monitor the pH, liquid level, and temperature of each chamber in real time, and adjust the electrolysis current through a PID algorithm. At the same time, monitor the redox potential of the acidic water, and automatically add a reducing agent when the potential exceeds the threshold. Step 2, Automatic pH Adjustment of Inlet Water: The acidic water prepared in Step 1 is continuously added to the inlet water pipe of the membrane system through a variable frequency metering pump. The control system reads the pH value of the inlet water in real time through an online pH meter, compares it with the preset value, and uses a PID algorithm to automatically adjust the stroke and frequency of the metering pump to control the pH of the inlet water in a closed loop. Step 3: Automatic pH adjustment of permeate: The alkaline water prepared in step 1 is continuously added to the permeate pipeline of the membrane system through a variable frequency metering pump. The control system reads the pH value of the permeate in real time through an online pH meter and compares it with the preset value. When the measured pH value deviates from the preset value, the addition amount is automatically adjusted. Step 4, Membrane Chemical Cleaning: The control system collects the operating parameters of the membrane system in real time; when the parameters reach the set threshold, it automatically determines the cleaning needs, identifies the type of fouling, and calls the corresponding cleaning formula from the preset formula library. According to the formula, it automatically extracts acidic / alkaline water from the electrolytic cell to the cleaning tank, dilutes it to the target concentration, and starts the cleaning pump to execute the cleaning program. Step 5, Neutralization Treatment of Cleaning Wastewater: Collect the acidic wastewater generated from pickling in Step 4 and the alkaline wastewater generated from alkali washing. When the cleaning wastewater is acidic, neutralize it using the alkaline water prepared in Step 1; when the cleaning wastewater is alkaline, neutralize it using the acidic water prepared in Step 1. The control system automatically calls the corresponding neutralizing agent according to the pH properties of the wastewater, and controls the amount of neutralizing agent added in real time through online pH meter feedback until the pH reaches the standard and then automatically discharges the wastewater.

[0007] Preferably, the reducing agent in step one is selected from sodium bisulfite or sodium thiosulfate; the threshold of the redox potential is set to 200-300mV, and the reducing agent is automatically added when the potential exceeds the threshold, and monitoring continues until the free chlorine concentration in the acidic water drops below 0.05mg / L.

[0008] Preferably, the pH value of the influent in step two is predetermined to be 6.5.

[0009] Preferably, the pH value of the product water in step three is predetermined to be 7.5.

[0010] Preferably, in step four, the acid washing uses a hydrochloric acid solution with a pH of 2-3; the alkaline washing uses a sodium hydroxide solution with a pH of 11-12.

[0011] Preferably, in step four, the circulation flow rate of acid washing and alkaline washing is set to 0.8-1.5 m³ / h per membrane element, the soaking time is automatically selected from 30 to 120 minutes according to the degree of contamination, and the pH and turbidity of the cleaning solution are detected every 15-20 minutes during the cleaning process. Soaking is ended in advance when the turbidity change rate is <5%.

[0012] Preferably, in step five, the pH control target for the neutralized wastewater discharge is 6.5-7.5, and the conductivity of the wastewater is detected simultaneously. Discharge is only permitted when the conductivity is <2000µS / cm.

[0013] A novel fully automated reverse osmosis system integrating electrolysis technology is implemented through the aforementioned fully automated reverse osmosis process based on integrated electrolysis technology. The system consists of an electrolysis acid and alkali generation unit, an automatic feed water pH adjustment unit, an automatic product water pH adjustment unit, a membrane chemical cleaning unit, a cleaning waste liquid neutralization and treatment unit, and a central control system. The electrolytic acid and alkali production unit is used to simultaneously prepare acidic and alkaline water by electrolyzing sodium chloride solution, and has a built-in reducing agent dosing device that automatically adds reducing agent when the redox potential of acidic water exceeds the threshold. The automatic pH adjustment unit for the influent is connected to the acidic water outlet of the electrolytic acid and alkali production unit and the influent pipe of the membrane system. It controls the pH of the influent to 6.0 to 7.0 through a closed loop control using a variable frequency metering pump and an online pH meter. The automatic pH adjustment unit for the produced water is connected to the alkaline water outlet of the electrolytic acid and alkali production unit and the produced water pipeline of the membrane system. It controls the pH of the produced water to 7.0 to 8.0 through a closed loop control using a variable frequency metering pump and an online pH meter. The membrane chemical cleaning unit includes a cleaning tank, a cleaning pump, an automatic switching valve group, and a preset formula library. It automatically calls the cleaning formula according to the rate of decrease in water production and the rate of increase in differential pressure of the membrane system, and performs cleaning by extracting acidic or alkaline water from the electrolytic acid and alkali production unit and diluting it. The cleaning wastewater neutralization treatment unit includes a neutralization reaction tank and an online pH meter. When the cleaning wastewater is acidic, it is neutralized by alkaline water produced by the electrolytic acid and alkali production unit. When the cleaning wastewater is alkaline, it is neutralized by acidic water produced by the electrolytic acid and alkali production unit until the pH reaches the standard before being discharged. The central control system includes a PLC controller and a host computer, which are used to perform low-level logic control such as PID regulation, threshold judgment, valve switching and pump start / stop, as well as parameter setting, status monitoring and historical data query.

[0014] Preferably, the electrolytic cell device is one of a four-chamber electrolytic cell or a bipolar membrane electrolytic cell.

[0015] Preferably, the PLC controller is used to execute low-level logic control, and the host computer is used to set parameters, monitor status, and query historical data.

[0016] Compared with existing technologies, this invention provides a novel fully automated reverse osmosis process and system integrating electrolysis technology, which has the following beneficial effects: 1. This invention integrates electrolytic acid and alkali production, feed water pH adjustment, product water pH adjustment, membrane chemical cleaning decision-making, and waste liquid neutralization treatment into a central control system. This achieves fully closed-loop automatic control from raw material addition to waste liquid discharge, requiring no manual intervention throughout the process. Specifically, a PID algorithm ensures pH adjustment accuracy and electrolysis product stability; automatic cleaning decision-making avoids blind cleaning; and a safety interlock mechanism effectively eliminates the risk of hydrogen combustion and explosion. Furthermore, the use of a four-chamber electrolyzer / bipolar membrane electrolyzer effectively prevents the generation of chlorine and hypochlorous acid, ensuring the purity of acidic water and preventing oxidative damage to membrane elements. Even if trace amounts of hypochlorous acid are generated, the oxidation risk can be further eliminated through a reduction dosing device, ultimately ensuring the safe operation of the membrane system.

[0017] 2. This invention utilizes an electrolysis device to produce both acidic and alkaline water, simultaneously meeting four major requirements: influent conditioning (inhibiting scaling), membrane chemical cleaning (acid washing and alkaline washing), product water pH adjustment (reaching 7.5), and neutralization treatment of cleaning wastewater. It eliminates the need to purchase chemicals such as hydrochloric acid, sodium hydroxide, and scale inhibitors. Compared to traditional processes, it significantly reduces the management costs and leakage risks associated with the procurement, transportation, and storage of hazardous chemicals, eliminating chemical safety hazards at the source.

[0018] 3. The raw material of this invention is only industrial salt (sodium chloride), which significantly reduces operating costs compared to purchasing acid and alkali solutions. At the same time, the acid and alkali wastewater generated during cleaning is neutralized in real time using self-produced acid and alkali water, and the discharge is precisely controlled to the pH 6-9 standard, which can achieve harmless discharge and no secondary pollution, thus meeting the requirements of green environmental protection. Attached Figure Description

[0019] Figure 1 This is a process application flowchart of an embodiment of the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Please see Figure 1A novel fully automated reverse osmosis process integrating electrolysis technology includes the following steps: Step 1: Electrolysis for Acid and Alkali Production: Start the electrolytic cell (using a four-chamber electrolytic cell or a bipolar membrane electrolytic cell), set the target current density, and electrolyze sodium chloride solution to prepare acidic and alkaline water. During the electrolysis process, monitor the pH, liquid level, and temperature of each chamber in real time, and adjust the electrolysis current using a PID algorithm to maintain stable product concentration. Simultaneously monitor the redox potential of the acidic water. When the potential exceeds the threshold, automatically add a reducing agent (sodium bisulfite or sodium thiosulfate) to reduce any hypochlorous acid that may be generated. When using a four-chamber electrolytic cell or a bipolar membrane electrolytic cell, the generation of chlorine and hypochlorous acid can be effectively avoided, ensuring the purity of the acidic water and preventing oxidative damage to the membrane elements. Even if trace amounts of hypochlorous acid are generated, the oxidation risk can be further eliminated through a reducing agent dosing device. Step 2: Automatic pH Adjustment of Inlet Water: The acidic water prepared in Step 1 is continuously added to the inlet water pipeline of the membrane system via a variable frequency metering pump. The control system reads the pH value of the inlet water in real time through an online pH meter and compares it with the preset value (6.0-7.0). The system uses a PID algorithm to automatically adjust the stroke and frequency of the metering pump, and performs closed-loop control of the inlet water pH. The PID algorithm ensures the accuracy of pH adjustment and the stability of electrolysis products. Automatic cleaning decision-making effectively avoids blind cleaning. The safety interlock mechanism eliminates the risks of hydrogen combustion and membrane oxidation damage. Step 3: Automatic pH adjustment of permeate: The alkaline water prepared in Step 1 is continuously added to the permeate pipeline of the membrane system through a variable frequency metering pump; the control system reads the pH value of the permeate in real time through an online pH meter and compares it with the preset value (7.0-8.0). When the measured pH value deviates from the preset value, the dosage is automatically adjusted. Step 4, Membrane Chemical Cleaning: The control system collects the operating parameters of the membrane system in real time (including the rate of decrease in permeate flow and the rate of increase in differential pressure); when the parameters reach the set threshold, it automatically determines the cleaning needs, identifies the type of fouling, and calls the corresponding cleaning formula from the preset formula library; it automatically switches the valve group to switch the membrane system to cleaning mode, and automatically extracts acidic or alkaline water from the electrolyzer to the cleaning tank according to the formula, dilutes it to the target concentration, starts the cleaning pump, and performs cleaning according to the "circulation → soaking → circulation" procedure; Step 5: Neutralization of cleaning wastewater: Collect the acidic wastewater generated from pickling in Step 4 and the alkaline wastewater generated from alkali washing; neutralize the acidic wastewater with the alkaline water prepared in Step 1, or neutralize the alkaline wastewater with the acidic water prepared in Step 1; the control system automatically calls the corresponding neutralizing agent according to the pH properties of the wastewater (acidic wastewater is neutralized with self-produced alkaline water, and alkaline wastewater is neutralized with self-produced acidic water), and controls the amount of neutralizing agent added in real time through online pH meter feedback, until the pH reaches the standard and then automatically discharges the wastewater.

[0022] Specifically, in step one, the reducing agent is selected from either sodium bisulfite or sodium thiosulfate; the threshold value of the oxidation-reduction potential is set to 200-300mV, and the reducing agent is automatically added when the potential exceeds the threshold value, and monitoring continues until the free chlorine concentration in the acidic water drops below 0.05mg / L.

[0023] Specifically, in step two, the pH value of the influent is predetermined to be 6.0-7.0, more preferably 6.5. The stroke or frequency of the variable frequency metering pump is automatically adjusted by the PID algorithm to continuously add the acidic water prepared in step one into the influent pipe of the membrane system, so that the measured pH value is stable within the preset range.

[0024] Specifically, in step three, the pH value of the permeate is predetermined to be 7.0-8.0, more preferably 7.5. The dosage of the variable frequency metering pump is automatically adjusted by the PID algorithm to continuously add the alkaline water prepared in step one into the permeate pipeline of the membrane system, so that the measured pH value is stable within the preset range.

[0025] Specifically, in step four, acid washing uses a hydrochloric acid solution with a pH of 2-3; alkaline washing uses a sodium hydroxide solution with a concentration of 11-12. The control system automatically calculates the dilution ratio based on the target concentration in the formula, quantitatively extracts acidic or alkaline water from the electrolytic cell to the cleaning tank, and replenishes clean water. An online conductivity meter is used to confirm that the concentration has reached the target value.

[0026] Specifically, in step four, the circulation flow rate for acid washing and alkaline washing is set to 0.8-1.5 m³ / h per membrane element. The soaking time is automatically selected from 30 to 120 minutes based on the degree of fouling. When the differential pressure rise rate of the membrane system is less than 10% of the initial value, a 30-minute soaking time is selected; when the differential pressure rise rate is greater than 20% of the initial value, a 120-minute soaking time is selected; when the differential pressure rise rate is between 10% and 20%, the soaking time is automatically determined by linear interpolation based on the type of fouling. During the cleaning process, the pH and turbidity of the cleaning solution are detected every 15-20 minutes. When the turbidity change rate is <5%, the soaking is terminated early. The differential pressure sensor signal of the membrane system is collected in real time by the PLC controller, the percentage of the differential pressure rise rate to the initial value is calculated, and the soaking time is automatically selected based on the built-in judgment logic. At the same time, data is obtained every 15-20 minutes by the online turbidity meter and pH meter. When the turbidity change rate is less than 5% twice consecutively, the central control system issues a command to terminate the soaking program early.

[0027] Specifically, in step four, the cleaning formula includes: (1) Pickling formula (for inorganic scaling): Use the acidic water prepared in step one, and dilute it to a solution with a hydrochloric acid pH of 2 to 3; (2) Alkaline washing formula (for organic or microbial contamination): Use the alkaline water prepared in step one, dilute it to a sodium hydroxide solution with a pH of 11-12, and add 0.05%-0.2% of nonionic surfactant (selected from fatty alcohol polyoxyethylene ether or alkylphenol polyoxyethylene ether) and 0.02%-0.1% of chelating agent. (3) Two-step formula for compound pollution: first alkaline washing followed by acid washing. The alkaline washing and acid washing adopt the above alkaline washing formula and acid washing formula respectively. The alkaline washing is circulated for 45-60 minutes and soaked for 30-60 minutes. The acid washing is circulated for 30-45 minutes and soaked for 20-40 minutes. The product water is used to rinse in between until pH≤8.5.

[0028] Specifically, in step five, the pH control target for the neutralized wastewater discharge is 6.5-7.5. At the same time, the conductivity of the wastewater is detected. Discharge is only allowed when the conductivity is <2000µS / cm. The control system connects to an online pH meter and conductivity meter to read the data in real time. When both pH and conductivity meet the discharge threshold, the discharge valve of the neutralization tank is automatically opened. When only the pH meets the standard but the conductivity exceeds the standard, the neutralization continues and an appropriate amount of clean water is added for dilution until the conductivity meets the standard.

[0029] A novel fully automated reverse osmosis system integrating electrolysis technology is implemented through the aforementioned fully automated reverse osmosis process based on integrated electrolysis technology. The system consists of an electrolysis acid and alkali generation unit, an automatic feed water pH adjustment unit, an automatic product water pH adjustment unit, a membrane chemical cleaning unit, a cleaning waste liquid neutralization and treatment unit, and a central control system. The electrolytic acid and alkali production unit is used to simultaneously prepare acidic and alkaline water by electrolyzing sodium chloride solution. It has a built-in reducing agent dosing device that automatically adds reducing agent when the redox potential of acidic water exceeds the threshold. The electrolysis of sodium chloride solution is achieved through a four-chamber or bipolar membrane electrolyzer, a programmable DC power supply, and a PID constant current control module. It also has a built-in reducing agent metering pump that automatically adds reducing agent when the online ORP instrument detects that the redox potential of acidic water exceeds 200-300mV. The automatic pH adjustment unit for influent is connected to the acidic water outlet of the electrolytic acid and alkali production unit and the influent pipe of the membrane system. It achieves automatic stabilization of the influent pH at 6.0-7.0 through a variable frequency metering pump, an online pH meter, and a PLC closed-loop PID algorithm. The automatic pH adjustment unit for the product water is connected to the alkaline water outlet of the electrolytic acid and alkali production unit and the product water pipeline of the membrane system. It achieves automatic stabilization of the product water pH at 7.0-8.0 through a variable frequency metering pump, an online pH meter and a PLC closed-loop PID algorithm. The membrane chemical cleaning unit includes a cleaning tank, a cleaning pump, an automatic switching valve group, and a preset formula library. It automatically calls the cleaning formula according to the rate of decrease in permeate flow and the rate of increase in differential pressure of the membrane system. It extracts acidic or alkaline water from the electrolytic acid and alkali production unit, dilutes it, and performs "circulation → soaking → circulation" cleaning. The cleaning is automatically triggered by the pressure sensor, flow meter and PLC logic. The pipeline is switched by the pneumatic valve group, the flow rate is adjusted by the frequency converter of the cleaning pump, and the cleaning tank is equipped with a heater to maintain the optimal cleaning temperature. The cleaning wastewater neutralization treatment unit includes a neutralization reaction tank and an online pH meter. When the cleaning wastewater is acidic, it is neutralized with alkaline water produced by the electrolytic acid and alkali production unit. When the cleaning wastewater is alkaline, it is neutralized with acidic water produced by the electrolytic acid and alkali production unit until the pH reaches the standard before discharge. The system achieves automatic neutralization of the wastewater through an online pH meter, conductivity meter, and neutralizing agent dosing pump. The system automatically selects to use self-produced acidic or alkaline water as the neutralizing agent based on the initial pH of the wastewater. The central control system includes a PLC controller and a host computer, which is used to perform low-level logic control such as PID regulation, threshold judgment, valve switching, pump start and stop, as well as parameter setting, status monitoring and historical data query. All parameters can be set, displayed, alarmed and recorded through PLC, touch screen and host computer software. The PID regulation cycle is set to 0.5-2 seconds and remote monitoring is supported.

[0030] The electrolytic cell device is either a four-chamber electrolytic cell or a bipolar membrane electrolytic cell. During the electrolysis process, the electrolytic cell device completely avoids the generation of chlorine gas through a structural design that separates the anode chamber from the acid chamber or the water dissociation effect of the bipolar membrane.

[0031] The PLC controller is used to execute low-level logic control, while the host computer is used for parameter setting, status monitoring, and historical data querying.

[0032] The raw material for this invention is only industrial salt. Compared with purchasing acid and alkali solutions, the operating cost is significantly reduced, and the waste liquid is discharged in a harmless manner. The control system integrates electrolysis, pH adjustment, cleaning decision-making, and waste liquid treatment into one, which can realize a closed-loop automatic control from raw material addition to waste liquid discharge, without the need for manual intervention. By using the electrolysis device to produce acid and alkali, it can simultaneously meet the four major needs of feed water conditioning, membrane cleaning, product water conditioning, and waste liquid neutralization, thereby significantly reducing the management cost and storage risk of hazardous chemicals.

[0033] The process of the present invention is applied to the following embodiments: Example This embodiment provides a membrane system cleaning and pH adjustment process based on electrolytic acid and alkali production, which is applied to a seawater desalination reverse osmosis membrane system.

[0034] Process system composition: Electrolytic cell device: A bipolar membrane electrolytic cell is used, with sodium chloride solution as raw material, to electrolyze and generate acidic water (hydrochloric acid solution, concentration 7%-15%) and alkaline water (sodium hydroxide solution, concentration 25%-32%).

[0035] Reduction dosing device: contains sodium bisulfite solution, used to reduce trace amounts of hypochlorous acid that may be generated in acidic water.

[0036] Membrane system: Seawater desalination reverse osmosis membrane unit.

[0037] Cleaning tank: Used for preparing cleaning solutions and performing membrane chemical cleaning.

[0038] The process steps are as follows: S1. Electrolysis to produce acid and alkali: Start the electrolytic cell device and use refined sodium chloride solution as raw material to electrolyze and prepare acidic water and alkaline water. The acidic water is treated by a reduction dosing device, and sodium bisulfite is added to reduce any hypochlorous acid that may be present, ensuring that the oxidation-reduction potential (ORP) of the acidic water is below 200mV. S2. Automatic pH adjustment of influent: The prepared acidic water is continuously added to the influent pipe of the seawater desalination membrane system through a metering pump. The pH of the influent is monitored in real time by an online pH meter. The dosage is adjusted by PID control to keep the pH of the influent stable at 6.5. Under this pH condition, the formation of scale such as calcium carbonate can be effectively inhibited, reducing the risk of membrane scaling. S3. Automatic pH adjustment of permeate water: The prepared alkaline water is continuously added to the permeate water pipeline of the membrane system through a metering pump. The pH of the permeate water is monitored in real time by an online pH meter. The dosage is adjusted by PID control to keep the pH of the permeate water stable at 7.5, which meets the requirements of drinking water or subsequent processes for the pH of the permeate water. S4. Membrane Chemical Cleaning: When the membrane system operating differential pressure rises to a set value (e.g., 1.5 times the initial differential pressure) or the permeate flow rate drops to a set value, the cleaning procedure is initiated. (1) Pickling: When it is determined that the fouling is due to inorganic scaling, acidic water is taken from the electrolytic cell to the cleaning tank, and product water is added to dilute the solution to a pH value of 2~3. The membrane system is then circulated and pickled using a cleaning pump. (2) Alkaline washing: When it is determined that the contamination is caused by organic matter or microorganisms, alkaline water is taken from the electrolytic cell to the cleaning tank, and product water is added to dilute the solution to a pH value of 11~12. Add EDTA, surfactants and other additives as needed, and circulate alkaline washing of the membrane system through the cleaning pump. (3) After cleaning, rinse the membrane system with product water until the effluent pH is neutral, and then resume operation; S5. Neutralization treatment of cleaning wastewater: Acidic wastewater generated from pickling is discharged into a neutralization tank. Alkaline water is taken from the electrolytic cell and added to the neutralization tank. The amount of water added is controlled by monitoring with an online pH meter until the pH reaches the discharge standard of 6-9. Alkaline wastewater generated from alkali washing is discharged into a neutralization tank. Acidic water is taken from the electrolytic cell and added to the neutralization tank. Similarly, the pH is controlled until it meets the standard before discharge.

[0039] Process effect: This embodiment realizes four major functions of the seawater desalination membrane system at the same time through an electrolytic acid and alkali production device: control of scale formation in the feed water, pH adjustment of the product water, chemical cleaning of the membrane, and neutralization treatment of cleaning waste liquid. There is no need to purchase chemicals such as hydrochloric acid, sodium hydroxide, and scale inhibitors. The operating cost is reduced by 40% compared with the traditional method, the risk of chemical storage is minimized, and the cleaning waste liquid is discharged in a harmless manner.

[0040] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art 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 appended claims and their equivalents.

Claims

1. A novel fully automated reverse osmosis process integrating electrolysis technology, characterized in that, Includes the following steps: Step 1: Electrolysis to produce acid and alkali: Start the electrolytic cell, set the target current density, and electrolyze sodium chloride solution to prepare acidic and alkaline water. During the electrolysis process, monitor the pH, liquid level, and temperature of each chamber in real time, and adjust the electrolysis current through a PID algorithm; at the same time, monitor the redox potential of the acidic water, and automatically add a reducing agent when the potential exceeds the threshold. Step 2, Automatic pH Adjustment of Inlet Water: The acidic water prepared in Step 1 is continuously added to the inlet water pipe of the membrane system through a variable frequency metering pump. The control system reads the pH value of the inlet water in real time through an online pH meter, compares it with the preset value, and uses a PID algorithm to automatically adjust the stroke and frequency of the metering pump to control the pH of the inlet water in a closed loop. Step 3: Automatic pH adjustment of permeate: The alkaline water prepared in Step 1 is continuously added to the permeate pipeline of the membrane system through a variable frequency metering pump. The control system reads the pH value of the permeate in real time through an online pH meter and compares it with the preset value. When the measured pH value deviates from the preset value, the addition amount is automatically adjusted. Step 4, Membrane Chemical Cleaning: The control system collects the operating parameters of the membrane system in real time; when the parameters reach the set threshold, it automatically determines the cleaning needs, identifies the type of fouling, and calls the corresponding cleaning formula from the preset formula library. According to the formula, it automatically extracts acidic / alkaline water from the electrolytic cell to the cleaning tank, dilutes it to the target concentration, and starts the cleaning pump to execute the cleaning program. Step 5, Neutralization Treatment of Cleaning Wastewater: Collect the acidic wastewater generated from pickling in Step 4 and the alkaline wastewater generated from alkali washing. When the cleaning wastewater is acidic, neutralize it using the alkaline water prepared in Step 1; when the cleaning wastewater is alkaline, neutralize it using the acidic water prepared in Step 1. The control system automatically calls the corresponding neutralizing agent according to the pH properties of the wastewater, and controls the amount of neutralizing agent added in real time through online pH meter feedback until the pH reaches the standard and then automatically discharges the wastewater.

2. The novel fully automated reverse osmosis process integrating electrolysis technology according to claim 1, characterized in that, In step one, the reducing agent is selected from sodium bisulfite or sodium thiosulfate; the threshold of the redox potential is set to 200-300mV. When the potential exceeds the threshold, the reducing agent is automatically added, and monitoring continues until the free chlorine concentration in the acidic water drops below 0.05mg / L.

3. The novel fully automated reverse osmosis process integrating electrolysis technology according to claim 1, characterized in that, In step two, the predetermined pH value of the influent is 6.0-7.

0.

4. The novel fully automated reverse osmosis process integrating electrolysis technology according to claim 1, characterized in that, The pH value of the product water in step three is predetermined to be 7.0-8.

0.

5. A novel fully automated reverse osmosis process integrating electrolysis technology according to claim 1, characterized in that, In step four, the acid washing uses a hydrochloric acid solution with a pH of 2-3; the alkaline washing uses a sodium hydroxide solution with a pH of 11-12.

6. A novel fully automated reverse osmosis process integrating electrolysis technology according to claim 1, characterized in that, In step four, the circulation flow rate of acid washing and alkaline washing is set to 0.8-1.5 m³ / h per membrane element. The soaking time is automatically selected from 30 to 120 minutes according to the degree of contamination. During the cleaning process, the pH and turbidity of the cleaning solution are detected every 15-20 minutes. The soaking is terminated in advance when the turbidity change rate is <5%.

7. A novel fully automated reverse osmosis process integrating electrolysis technology according to claim 1, characterized in that, In step five, the pH control target for the neutralized wastewater discharge is 6.5-7.

5. At the same time, the conductivity of the wastewater is detected, and it can only be discharged when the conductivity is <2000µS / cm.

8. A novel fully automated reverse osmosis system integrating electrolysis technology, characterized in that, The novel fully automated reverse osmosis process integrating electrolysis technology as described in claim 1 is implemented through a system comprising an electrolysis acid and alkali generation unit, an automatic feed water pH adjustment unit, an automatic product water pH adjustment unit, a membrane chemical cleaning unit, a cleaning waste liquid neutralization and treatment unit, and a central control system. The electrolytic acid and alkali production unit is used to simultaneously prepare acidic and alkaline water by electrolyzing sodium chloride solution, and has a built-in reducing agent dosing device that automatically adds reducing agent when the redox potential of acidic water exceeds the threshold. The automatic pH adjustment unit for the influent is connected to the acidic water outlet of the electrolytic acid and alkali production unit and the influent pipe of the membrane system. It controls the pH of the influent to 6.0 to 7.0 through a closed loop control using a variable frequency metering pump and an online pH meter. The automatic pH adjustment unit for the produced water is connected to the alkaline water outlet of the electrolytic acid and alkali production unit and the produced water pipeline of the membrane system. It controls the pH of the produced water to 7.0 to 8.0 through a closed loop control using a variable frequency metering pump and an online pH meter. The membrane chemical cleaning unit includes a cleaning tank, a cleaning pump, an automatic switching valve group, and a preset formula library. It automatically calls the cleaning formula according to the rate of decrease in water production and the rate of increase in differential pressure of the membrane system, and performs cleaning by extracting acidic or alkaline water from the electrolytic acid and alkali production unit and diluting it. The cleaning wastewater neutralization treatment unit includes a neutralization reaction tank and an online pH meter. When the cleaning wastewater is acidic, it is neutralized by alkaline water produced by the electrolytic acid and alkali production unit. When the cleaning wastewater is alkaline, it is neutralized by acidic water produced by the electrolytic acid and alkali production unit until the pH reaches the standard before being discharged. The central control system includes a PLC controller and a host computer, which are used to perform low-level logic control such as PID regulation, threshold judgment, valve switching and pump start / stop, as well as parameter setting, status monitoring and historical data query.

9. A novel fully automated reverse osmosis system integrating electrolysis technology according to claim 8, characterized in that, The electrolytic cell device is either a four-chamber electrolytic cell or a bipolar membrane electrolytic cell.

10. A novel fully automated reverse osmosis system integrating electrolysis technology according to claim 8, characterized in that, The PLC controller is used to execute low-level logic control, and the host computer is used to set parameters, monitor status, and query historical data.

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