Recycling washing water treatment process and treatment system for sodium chloride high-salinity wastewater

Abstract

The invention relates to the technical field of wastewater treatment, and discloses a recycling washing water treatment process of sodium chloride high-salinity wastewater, which comprises the following steps: step 1, a pretreatment stage: recycling washing water with a pH value range of 6-9 and main solutes of NaCl and Ca < 2 + lt >; 350mg / L, Mg < 2 + lt >; the method comprises the following steps: introducing washing water with the concentration of 350mg / L and the TDS of more than 100g / L into a multi-medium filter, removing impurities in the washing water through a multi-layer filtering structure by utilizing the adsorption and interception effects of a filtering medium, and controlling the filtering speed to be 8-12m / h; and step 2, a hardness removal stage: the water treated by the multi-medium filter enters a hardness removal resin device, and strong-acid cation exchange resin is adopted to carry out ion exchange reaction with Ca < 2 + > and Mg < 2 + > in the water to remove calcium and magnesium ions in the water. And in the hardness removal process, the flow speed is controlled to be 4-6 m / h. Water resources and salt in washing water are fully separated and recycled, no by-product pollutant is discharged into the environment, pollution to soil, water and atmosphere is greatly reduced, and balance of the ecological environment is protected.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to a resource-based washing water treatment process and a treatment system for sodium chloride high-salt wastewater. Background Art

[0002] With the acceleration of industrialization, many industries such as chemical, pharmaceutical, printing and dyeing, food processing, etc. have produced a large amount of high-salt wastewater in the production process. Among them, high-salt wastewater containing sodium chloride has become a major problem in the field of wastewater treatment due to its complex composition and high salinity. In the chemical industry, many production processes involve a large number of chemical reactions, in which sodium chloride, as a common by-product or reaction medium, will be discharged with production wastewater. For example, in the chlor-alkali industry, a large amount of wastewater containing sodium chloride will be produced in the process of electrolyzing salt water to produce caustic soda, chlorine and hydrogen. If these wastewaters are discharged directly without effective treatment, they will cause serious pollution to the soil and water bodies. In the dyeing and printing processes, the printing and dyeing industry needs to use a large amount of salt additives to promote dyeing and fixation of dyes, resulting in a high concentration of sodium chloride in the generated wastewater. These high-salt wastewaters will not only cause soil salinization and affect the growth of crops, but also damage the ecological balance of surrounding water bodies, leading to the deterioration of the living environment of aquatic organisms.

[0003] The existing methods for treating high-salinity wastewater mainly include biological treatment, physical and chemical methods, and membrane separation. However, these methods all have certain limitations. Although the biological treatment method has relatively low cost, it has poor adaptability to high-salinity environments, and the activity of microorganisms is easily inhibited, resulting in unstable treatment effects and difficulty in meeting increasingly stringent environmental protection requirements. Although physical and chemical methods such as precipitation, coagulation, and adsorption can remove some pollutants, they have limited effects on the removal of salt and cannot achieve resource utilization of wastewater. Although the membrane separation method has certain advantages in the removal of salt and pollutants, it has problems such as serious membrane pollution, high operating costs, and short service life, which limit its large-scale application. In addition, traditional high-salinity wastewater treatment methods often only focus on meeting discharge standards and ignore the recycling of valuable components in wastewater. This not only causes a waste of resources, but also increases the treatment costs of enterprises. At the same time, the discharge of a large amount of high-salinity wastewater has also placed a heavy burden on the environment and triggered a series of ecological and environmental problems. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a resource-based washing water treatment process and a treatment system for sodium chloride high-salt wastewater, which solves the problems existing in the existing high-salt wastewater treatment process.

[0005] To achieve the above objectives, the present invention is implemented by the following technical scheme: a resource-based washing water treatment process for sodium chloride high-salt wastewater, comprising the following steps:

[0006] Step 1: In the pretreatment stage, the wash water with a pH value of 6-9, main solutes of NaCl, Ca2+<350mg / L, Mg2+<350mg / L, and TDS>100g / L is introduced into the multi-media filter, and the impurities in the wash water are removed by the adsorption and interception effect of the filter medium through the multi-layer filtration structure, and the filtration speed is controlled at 8-12m / h;

[0007] Step 2, hardness removal stage, the water treated by the multi-media filter enters the hardness removal resin device, and the strong acid cation exchange resin is used to react with Ca2+ and Mg2+ in the water to remove calcium and magnesium ions in the water. During the hardness removal process, the flow rate is controlled to be 4-6m / h, the contact time is 0.4-0.6h, and when the resin reaches saturation, it is regenerated with hydrochloric acid solution, and the concentration of the regeneration solution is 3%-5% hydrochloric acid;

[0008] Step 3: Fine filtration stage: the water after hardening enters the self-cleaning filter to further filter out tiny particles and impurities. The filtration accuracy is 30-60μm. When the pressure difference between the inside and outside of the self-cleaning filter reaches 0.05-0.1MPa, the cleaning program is automatically started to remove impurities on the filter by backwashing.

[0009] Step 4, conversion stage, the water treated by the self-cleaning filter enters the bipolar membrane device, and under the action of the electric field, the water decomposition layer in the bipolar membrane undergoes a water dissociation reaction to produce hydrogen ions and hydroxide ions. The hydrogen ions migrate to the cathode and combine with the chloride ions that pass through the anion exchange membrane to form hydrochloric acid. The hydroxide ions migrate to the anode and combine with the sodium ions that pass through the cation exchange membrane to form sodium hydroxide. The bipolar membrane device operates under the conditions of a voltage of 18-25V and a current of 8-15A;

[0010] Step 5: Water resource recovery stage: the brine produced by the bipolar membrane device is collected and sent to the front end of the system to be mixed with the raw water for circulation treatment;

[0011] Step 6, acid-base recovery stage, the generated 8% sodium hydroxide is subjected to an acid evaporation and concentration process to obtain 32% sodium hydroxide, and the generated 7% hydrochloric acid is collected at the same time. The condensed water generated by the liquid alkali evaporation and concentration device is collected separately, and then filtered and disinfected with a filtration accuracy of 5-10μm to remove tiny particle impurities, and then the ultraviolet sterilizer is used to kill bacteria and microorganisms. The treated condensed water is reused as reclaimed water.

[0012] Preferably, in the pretreatment stage, backwashing operation is performed regularly, and backwashing water enters from the bottom water outlet of the multi-media filter, passes through the filter material layer from bottom to top, and washes away impurities intercepted on the filter material surface and in the pores. The backwashing water is discharged through the drainage end at the top of the multi-media filter. The backwashing cycle is 24-48 hours.

[0013] Preferably, in the hardness removal stage, the regeneration process of the resin device is:

[0014] First, loosen the failed resin by backwashing to make the resin layer evenly loose, and then slowly inject regeneration liquid from the regeneration liquid inlet. The contact time between the regeneration liquid and the resin is not less than 30 minutes. After the regeneration is completed, rinse the resin with clean water until the water quality after flushing meets the requirements of subsequent treatment.

[0015] Preferably, the backwashing process is:

[0016] Driven by the motor, the cleaning brush rotates along the inner wall of the filter to scrape off the impurities intercepted on the filter. At the same time, backwash water enters from the bottom water outlet to flush the scraped impurities out of the filter and discharge them through the drain port.

[0017] The present invention also provides a resource-based washing water treatment system for sodium chloride high-salt wastewater, the treatment system is applied to the above-mentioned resource-based washing water treatment process for sodium chloride high-salt wastewater, and the treatment system comprises:

[0018] The multi-media filter is made of high-strength fiberglass and is filled with three layers of filter media, which are anthracite filter media with a particle size of 2-4mm, quartz sand filter media with a particle size of 0.8-1.2mm, and garnet filter media with a particle size of 0.5-0.8mm from top to bottom. The multi-media filter is provided with a water inlet at the top, which adopts a tangential water inlet method to form a vortex in the tank body. The bottom is provided with a water outlet, which ensures uniform water outlet through a water distribution plate. A backwashing device is also provided to backwash the filter media regularly.

[0019] The hard resin removal device is made of corrosion-resistant engineering plastic material, and is filled with strong acidic cation exchange resin. The filling height is 70%-80% of the tank height. The hard resin removal device is provided with a water inlet, a water outlet, a regeneration liquid inlet and a regeneration liquid outlet. The water inlet is located at the top of the hard resin removal device, so that the washing water passes through the resin layer from top to bottom. The water outlet is located at the bottom of the hard resin removal device, and the water after hardness removal flows out from here. The regeneration liquid inlet and the regeneration liquid outlet are respectively located at the top and the bottom of the hard resin removal device, and are used to introduce and discharge the regeneration liquid during resin regeneration.

[0020] The self-cleaning filter has a shell made of stainless steel 316L, and the internal filter is a stainless steel woven mesh with a filtration accuracy of 30-60μm. It is equipped with a water inlet, a water outlet and a sewage outlet. A cleaning brush is installed on the inside of the filter. When the pressure difference between the inside and outside of the filter reaches the set value, the automatic control system starts the cleaning program. The cleaning brush cleans the filter under the drive of the motor, and the backwash water discharges impurities at the same time.

[0021] A bipolar membrane device, which is composed of a bipolar membrane group, electrodes, a partition and a frame. The bipolar membrane group is composed of a plurality of bipolar membranes arranged in sequence, each bipolar membrane is separated by a partition to form an independent water flow channel. The bipolar membrane adopts a composite membrane material, and the electrode adopts a titanium-coated ruthenium electrode. The bipolar membrane device is provided with a water inlet, a concentrated water outlet, a fresh water outlet, a sodium hydroxide outlet and a hydrochloric acid outlet. The sodium chloride solution is converted by the action of an electric field to produce sodium hydroxide and hydrochloric acid, which are discharged from the corresponding outlets respectively.

[0022] The condensed water recovery device includes a water collection tank, a filter and a sterilizer. The water collection tank is made of stainless steel and is used to collect the condensed water generated by the bipolar membrane device. The filter has a filtration accuracy of 5-10 μm and further removes tiny particle impurities in the condensed water. The sterilizer is an ultraviolet sterilizer, which uses the bactericidal effect of ultraviolet rays to kill bacteria and microorganisms in the condensed water.

[0023] The acid-base separation and treatment device includes a sodium hydroxide evaporation and concentration system and a hydrochloric acid storage and preparation system. The sodium hydroxide evaporation and concentration system uses a triple-effect evaporator to concentrate an 8% sodium hydroxide solution to 32% through multiple evaporations and condensations. The hydrochloric acid storage and preparation system consists of a hydrochloric acid storage tank and a preparation device. The hydrochloric acid storage tank is made of corrosion-resistant plastic material and is used to store 7% hydrochloric acid produced by a bipolar membrane device.

[0024] The automatic control system adopts a programmable logic controller as a core control unit, and also includes a pressure sensor and a flow sensor arranged on the water inlet pipe of the multi-media filter for monitoring the pressure and flow of the inlet water, a water quality sensor arranged at the water outlet end of the hard resin removal device for monitoring the calcium and magnesium ion content of the outlet water, a pressure difference sensor and a time sensor arranged on both sides of the filter screen of the self-cleaning filter for monitoring the pressure difference inside and outside the filter screen and the running time; a voltage sensor, a current sensor, a temperature sensor and a concentration sensor are installed in the bipolar membrane device for monitoring the electric field strength, current, solution temperature and solution concentration parameters. The control unit automatically controls the start and stop of the system, the opening and closing of the valve and the dosing operation according to the preset program and the collected parameters.

[0025] Preferably, the multi-media filter is connected to the hard resin removal device via a corrosion-resistant pipe, and a flow regulating valve is provided on the corrosion-resistant pipe to adjust the water flow rate according to the amount of treated water and the water quality.

[0026] Preferably, a water quality monitor is installed on the connecting pipe between the hardness resin removal device and the self-cleaning filter for real-time monitoring of the water quality after hardness removal. If the water quality does not meet the standard, the water is returned to the hardness resin removal device for secondary treatment.

[0027] Preferably, a pressure buffer tank is provided on the pipeline between the self-cleaning filter and the bipolar membrane device to stabilize the water pressure entering the bipolar membrane device.

[0028] Preferably, a reflux pipe is provided between the concentrate outlet of the bipolar membrane device and the water inlet of the multi-media filter, and part of the concentrate can flow back to the multi-media filter for further treatment.

[0029] The present invention provides a resource-based washing water treatment process and treatment system for sodium chloride high-salt wastewater. It has the following beneficial effects:

[0030] 1. The present invention fully separates and recycles the water resources and salt in the wash water, and no by-product pollutants are discharged into the environment, which greatly reduces the pollution to the soil, water and atmosphere, and protects the balance of the ecological environment. The condensed water generated in the bipolar membrane treatment process is treated and reused as reclaimed water in the production process. This not only reduces the amount of fresh water resources used by enterprises, reduces the consumption of water resources, but also reduces the total amount of wastewater discharged.

[0031] 2. The present invention can achieve sodium ion balance by passing the wastewater generated in the production process through the wastewater treatment process. The generated sodium hydroxide can be reused in the chemical production process, avoiding the company's dependence on purchasing sodium hydroxide, thereby reducing the operating cost of the front-end production. At the same time, this process can also produce 7% hydrochloric acid, which the company can use for pickling, adjusting pH value and other process links according to its own production needs, reducing the purchase cost of hydrochloric acid. If the company's own usage is limited, the hydrochloric acid can also be sold to the outside, bringing additional economic benefits to the company. This way of wastewater resource utilization not only solves the problem of wastewater treatment, but also creates a new profit growth point for the company.

[0032] 3. The present invention adopts a treatment process consisting of a series of equipment such as a multi-media filter, a hardness removal resin, a self-cleaning filter, and a bipolar membrane. The equipment works together to form an efficient treatment system. In particular, the application of the bipolar membrane realizes the efficient conversion of sodium chloride solution, converting the salt in the wastewater into valuable sodium hydroxide and hydrochloric acid. This conversion method is leading in the field of high-salt wastewater treatment. By reasonably controlling the parameters of each treatment link, such as the filtration speed of the multi-media filter, the flow rate and contact time of the hardness removal resin device, the voltage and current of the bipolar membrane device, etc., the stable operation of the entire treatment system and the reliability of the treatment effect are ensured. At the same time, the treatment system is equipped with an automatic control system, which monitors the operating parameters of each device in real time through sensors, and automatically controls the start and stop of the equipment, the opening and closing of the valve, and the addition of drugs according to the preset program. This not only improves the operating efficiency and reduces the cost of manual operation, but also reduces the influence of human factors on the treatment effect, and improves the stability and reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1This is a flow chart of a process for treating sodium chloride high-salt wastewater as a resource;

[0034] Figure 2 It is a schematic diagram of the process of the pretreatment stage in the present invention;

[0035] Figure 3 It is a schematic diagram of the process of the hardness removal stage in the present invention;

[0036] Figure 4 It is a schematic diagram of the process of the fine filtration stage in the present invention;

[0037] Figure 5 This is a system diagram of a resource-based washing water treatment system for sodium chloride high-salt wastewater according to the present invention. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] Embodiment 1:

[0040] Please refer to the attached Figure 1 -Attached Figure 4 The embodiment of the present invention provides a resource-based washing water treatment process for sodium chloride high-salt wastewater, comprising the following steps:

[0041] Step 1: In the pretreatment stage, the wash water with a pH value of 6-9, main solutes of NaCl, Ca2+<350mg / L, Mg2+<350mg / L, and TDS>100g / L is introduced into the multi-media filter. Through the multi-layer filtration structure, the impurities in the wash water are removed by the adsorption and interception effect of the filter medium. The impurities include suspended matter, colloids, etc. The filtration speed is controlled at 8-12m / h to ensure that a reasonable treatment flux is maintained while effectively removing impurities;

[0042] Step 2, hardness removal stage, the water treated by the multi-media filter enters the hardness removal resin device, and a strong acidic cation exchange resin is used to react with Ca2+ and Mg2+ in the water to remove calcium and magnesium ions in the water. During the hardness removal process, the flow rate is controlled to be 4-6m / h, and the contact time is 0.4-0.6h to ensure that the calcium and magnesium ions react fully with the resin. When the resin reaches saturation, it is regenerated with hydrochloric acid solution. The concentration of the regeneration solution is 3%-5% hydrochloric acid. The exchange capacity of the resin is restored through the regeneration operation;

[0043] Step 3: Fine filtration stage: the water after hardening enters the self-cleaning filter to further filter tiny particles and impurities. The filtration accuracy is 30-60μm. When the pressure difference between the inside and outside of the self-cleaning filter reaches 0.05-0.1MPa, the cleaning program is automatically started to remove impurities on the filter by backwashing. Of course, the cleaning program is not only based on the pressure difference between the inside and outside of the filter, but also can be started according to the set time interval, such as automatically starting the cleaning program every 8-12 hours to ensure that the filter always maintains good filtration performance;

[0044] Step 4, conversion stage, the water treated by the self-cleaning filter enters the bipolar membrane device, and under the action of the electric field, the water decomposition layer in the bipolar membrane undergoes a water dissociation reaction to produce hydrogen ions and hydroxide ions. The hydrogen ions migrate to the cathode and combine with the chloride ions that pass through the anion exchange membrane to form hydrochloric acid. The hydroxide ions migrate to the anode and combine with the sodium ions that pass through the cation exchange membrane to form sodium hydroxide. The bipolar membrane device operates under the conditions of a voltage of 18-25V and a current of 8-15A to ensure that the sodium chloride solution is efficiently converted into sodium hydroxide and hydrochloric acid;

[0045] Step 5: Water resource recovery stage: the brine produced by the bipolar membrane device is collected and sent to the front end of the system to be mixed with the raw water for circulation treatment;

[0046] Step 6, acid and alkali recovery stage, the 8% sodium hydroxide produced is subjected to acid evaporation and concentration process to obtain 32% sodium hydroxide, and the 7% hydrochloric acid produced is collected at the same time, and the condensed water produced by the liquid alkali evaporation and concentration device is collected separately, and then filtered and disinfected. The filtration accuracy is 5-10μm, and tiny particles of impurities are removed. Then, the ultraviolet disinfector is used to kill bacteria and microorganisms, and the treated condensed water is reused as reclaimed water. It can be used for self-use according to the needs of the enterprise, such as for pickling, pH adjustment and other process links, or it can be packaged and sold to increase the economic benefits of the enterprise.

[0047] During the pretreatment stage, backwashing operations are performed regularly. Backwashing water enters from the bottom outlet of the multi-media filter, passes through the filter material layer from bottom to top, and washes away impurities intercepted on the filter material surface and in the pores. The backwashing water is discharged through the drain end at the top of the multi-media filter. The backwashing cycle is 24-48 hours.

[0048] In the hardness removal stage, the regeneration process of the resin device is as follows:

[0049] First, loosen the failed resin by backwashing to make the resin layer evenly loose, and then slowly inject regeneration liquid from the regeneration liquid inlet. The contact time between the regeneration liquid and the resin is not less than 30 minutes. After the regeneration is completed, rinse the resin with clean water until the water quality after flushing meets the requirements of subsequent treatment.

[0050] The backwashing process is:

[0051] Driven by the motor, the cleaning brush rotates along the inner wall of the filter to scrape off the impurities intercepted on the filter. At the same time, backwash water enters from the bottom water outlet to flush the scraped impurities out of the filter and discharge them through the drain port.

[0052] During operation, the bipolar membrane device optimizes the conversion effect of sodium chloride by adjusting parameters such as electric field strength, temperature and solution concentration. For example, the solution temperature is controlled at 25-35°C. Within this temperature range, the water decomposition efficiency and ion migration rate of the bipolar membrane are high, which is conducive to improving the generation efficiency of sodium hydroxide and hydrochloric acid.

[0053] Embodiment 2:

[0054] Please refer to the attached Figure 5 On the basis of the above embodiment, this embodiment provides a resource-based washing water treatment system for sodium chloride high-salt wastewater, which is applied to the above-mentioned resource-based washing water treatment process for sodium chloride high-salt wastewater. The treatment system includes:

[0055] The multi-media filter is made of high-strength fiberglass, has good corrosion resistance and mechanical strength, and can withstand high water pressure and water flow impact. It is filled with three layers of filter media, from top to bottom, anthracite filter media with a particle size of 2-4mm, quartz sand filter media with a particle size of 0.8-1.2mm, and garnet filter media with a particle size of 0.5-0.8mm. The multi-media filter is provided with a water inlet at the top, which uses a tangential water inlet method to form a vortex in the tank. The bottom is provided with a water outlet, which ensures uniform water output through a water distribution plate. At the same time, a backwashing device is also provided to regularly backwash the filter media to restore the filtering performance of the filter media.

[0056] The hard resin removal device is made of corrosion-resistant engineering plastics and filled with strong acidic cation exchange resin. The filling height is 70%-80% of the tank height to ensure sufficient exchange capacity. The hard resin removal device is provided with a water inlet, a water outlet, a regeneration liquid inlet and a regeneration liquid outlet. The water inlet is located at the top of the hard resin removal device so that the washing water passes through the resin layer from top to bottom. The water outlet is located at the bottom of the hard resin removal device, and the water after hardness removal flows out from here. The regeneration liquid inlet and the regeneration liquid outlet are located at the top and bottom of the hard resin removal device respectively, and are used to introduce and discharge the regeneration liquid during resin regeneration.

[0057] The self-cleaning filter has a shell made of stainless steel 316L and an internal filter screen made of stainless steel woven mesh, which has excellent corrosion resistance and a filtration accuracy of 30-60μm. It is equipped with a water inlet, a water outlet and a sewage outlet. A cleaning brush is provided on the inside of the filter screen. When the pressure difference between the inside and outside of the filter screen reaches the set value, the automatic control system starts the cleaning program. The cleaning brush cleans the filter screen under the drive of the motor, and the backwash water discharges impurities to ensure the normal operation of the filter.

[0058] The bipolar membrane device is composed of a bipolar membrane group, electrodes, partitions and a frame. The bipolar membrane group is composed of multiple bipolar membranes arranged in sequence. Each bipolar membrane is separated by a partition to form an independent water flow channel. The bipolar membrane adopts a composite membrane material, which has a lower membrane resistance and a higher water decomposition efficiency; the electrode adopts a titanium-coated ruthenium electrode, which has good conductivity and corrosion resistance. The bipolar membrane device is equipped with a water inlet, a concentrated water outlet, a fresh water outlet, a sodium hydroxide outlet and a hydrochloric acid outlet. The sodium chloride solution is converted through the action of an electric field to produce sodium hydroxide and hydrochloric acid, which are discharged from the corresponding outlets respectively.

[0059] The condensed water recovery device includes a water collection tank, a filter and a sterilizer. The water collection tank is made of stainless steel and is used to collect the condensed water generated by the bipolar membrane device. The filter has a filtration accuracy of 5-10μm to further remove tiny particle impurities in the condensed water. The sterilizer is an ultraviolet sterilizer, which uses the bactericidal effect of ultraviolet rays to kill bacteria and microorganisms in the condensed water to ensure that the water quality of the condensed water meets the standards for recycled water reuse. The treated condensed water can be transported to the water use link of the enterprise through pipelines;

[0060] Acid-base separation and treatment device, which includes a sodium hydroxide evaporation and concentration system and a hydrochloric acid storage and preparation system. The sodium hydroxide evaporation and concentration system uses a triple-effect evaporator to concentrate 8% sodium hydroxide solution to 32% through multiple evaporations and condensations. The evaporator is made of stainless steel and is equipped with a heating tube and an evaporation chamber. The hydrochloric acid storage and preparation system consists of a hydrochloric acid storage tank and a preparation device. The hydrochloric acid storage tank is made of corrosion-resistant plastic material and is used to store 7% hydrochloric acid produced by the bipolar membrane device. The preparation device can dilute or prepare hydrochloric acid according to the production needs of the enterprise;

[0061] The automatic control system adopts a programmable logic controller as a core control unit, and also includes a pressure sensor and a flow sensor arranged on the water inlet pipe of the multi-media filter for monitoring the pressure and flow of the inlet water, a water quality sensor arranged at the water outlet end of the hard resin removal device for monitoring the calcium and magnesium ion content of the outlet water, a pressure difference sensor and a time sensor arranged on both sides of the filter screen of the self-cleaning filter for monitoring the pressure difference inside and outside the filter screen and the running time; a voltage sensor, a current sensor, a temperature sensor and a concentration sensor are installed in the bipolar membrane device for monitoring the electric field strength, current, solution temperature and solution concentration parameters. The control unit automatically controls the start and stop of the system, the opening and closing of the valve and the dosing operation according to the preset program and the collected parameters, so as to realize the intelligent management of the whole treatment system.

[0062] The multi-media filter is connected to the hard resin removal device through a corrosion-resistant pipe. A flow regulating valve is provided on the corrosion-resistant pipe to adjust the water flow rate according to the treated water volume and water quality to ensure the stable operation of the hard resin removal device.

[0063] A water quality monitor is installed on the connecting pipe between the hardness removal resin device and the self-cleaning filter to monitor the water quality of the hardness removal water in real time. If the water quality does not meet the standard, the water will be returned to the hardness removal resin device for secondary treatment.

[0064] A pressure buffer tank is provided on the pipeline between the self-cleaning filter and the bipolar membrane device to stabilize the water pressure entering the bipolar membrane device and avoid damage to the bipolar membrane caused by water pressure fluctuations.

[0065] A return pipe is provided between the concentrated water outlet of the bipolar membrane device and the water inlet of the multi-media filter, and part of the concentrated water can be returned to the multi-media filter for further treatment, thereby improving the utilization rate of water resources.

[0066] The pipeline between the condensate recovery device and the enterprise water use link is equipped with an online water quality monitoring device to monitor the quality of the reclaimed water in real time to ensure that the reclaimed water meets the reuse standards. Once the water quality is abnormal, the automatic control system can take corresponding measures in time, such as stopping the reuse of reclaimed water or strengthening the treatment of condensate water.

[0067] The automation control system also has a remote monitoring function. Through a wireless network or a wired network, the operator can view the operating parameters and equipment status of the processing system in real time on the remote terminal, realize remote operation and fault diagnosis, and improve the management efficiency and response speed of the system.

[0068] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A resource-based washing water treatment process for sodium chloride high-salt wastewater, characterized in that: The following steps are involved: Step 1: In the pretreatment stage, the wash water with a pH value of 6-9, main solutes of NaCl, Ca2+<350mg / L, Mg2+<350mg / L, and TDS>100g / L is introduced into the multi-media filter, and the impurities in the wash water are removed by the adsorption and interception effect of the filter medium through the multi-layer filtration structure, and the filtration speed is controlled at 8-12m / h; Step 2, hardness removal stage, the water treated by the multi-media filter enters the hardness removal resin device, and a strong acidic cation exchange resin is used to react with Ca2+ and Mg2+ in the water to remove calcium and magnesium ions in the water. During the hardness removal process, the flow rate is controlled to be 4-6m / h, and the contact time is 0.4-0.6h. When the resin reaches saturation, it is regenerated with a hydrochloric acid solution, and the concentration of the regeneration solution is 3%-5% hydrochloric acid; Step 3: Fine filtration stage: the water after hardening enters the self-cleaning filter to further filter out tiny particles and impurities. The filtration accuracy is 30-60μm. When the pressure difference between the inside and outside of the self-cleaning filter reaches 0.05-0.1MPa, the cleaning program is automatically started to remove impurities on the filter by backwashing. Step 4, conversion stage, the water treated by the self-cleaning filter enters the bipolar membrane device, and under the action of the electric field, the water decomposition layer in the bipolar membrane undergoes a water dissociation reaction to produce hydrogen ions and hydroxide ions. The hydrogen ions migrate to the cathode and combine with the chloride ions that pass through the anion exchange membrane to form hydrochloric acid. The hydroxide ions migrate to the anode and combine with the sodium ions that pass through the cation exchange membrane to form sodium hydroxide. The bipolar membrane device operates under the conditions of a voltage of 18-25V and a current of 8-15A; Step 5: Water resource recovery stage: the brine produced by the bipolar membrane device is collected and sent to the front end of the system to be mixed with the raw water for circulation treatment; Step 6, acid-base recovery stage, the generated 8% sodium hydroxide is subjected to an acid evaporation and concentration process to obtain 32% sodium hydroxide, and the generated 7% hydrochloric acid is collected at the same time. The condensed water generated by the liquid alkali evaporation and concentration device is collected separately, and then filtered and disinfected with a filtration accuracy of 5-10μm to remove tiny particle impurities, and then the ultraviolet sterilizer is used to kill bacteria and microorganisms. The treated condensed water is reused as reclaimed water.

2. The resource-based washing water treatment process for sodium chloride high-salt wastewater according to claim 1, characterized in that: During the pretreatment stage, backwashing operations are performed regularly. Backwashing water enters from the bottom outlet of the multi-media filter, passes through the filter material layer from bottom to top, and washes away impurities intercepted on the filter material surface and in the pores. The backwashing water is discharged through the drain end at the top of the multi-media filter. The backwashing cycle is 24-48 hours.

3. The resource-based washing water treatment process for sodium chloride high-salt wastewater according to claim 1, characterized in that: In the hardness removal stage, the regeneration process of the resin device is as follows: First, loosen the failed resin by backwashing to make the resin layer evenly loose, and then slowly inject regeneration liquid from the regeneration liquid inlet. The contact time between the regeneration liquid and the resin is not less than 30 minutes. After the regeneration is completed, rinse the resin with clean water until the water quality after flushing meets the requirements of subsequent treatment.

4. The resource-based washing water treatment process for sodium chloride high-salt wastewater according to claim 1, characterized in that: The backwashing process is: Driven by the motor, the cleaning brush rotates along the inner wall of the filter to scrape off the impurities intercepted on the filter. At the same time, backwash water enters from the bottom water outlet to flush the scraped impurities out of the filter and discharge them through the drain port.

5. A resource-based washing water treatment system for sodium chloride high-salt wastewater, characterized in that: The treatment system is applied to a resource-based washing water treatment process for sodium chloride high-salt wastewater according to any one of claims 1 to 4, and the treatment system comprises: The multi-media filter is made of high-strength fiberglass and is filled with three layers of filter media, which are anthracite filter media with a particle size of 2-4mm, quartz sand filter media with a particle size of 0.8-1.2mm, and garnet filter media with a particle size of 0.5-0.8mm from top to bottom. The multi-media filter is provided with a water inlet at the top, which adopts a tangential water inlet method to form a vortex in the tank body. The bottom is provided with a water outlet, which ensures uniform water outlet through a water distribution plate. A backwashing device is also provided to backwash the filter media regularly. The hard resin removal device is made of corrosion-resistant engineering plastic material, and is filled with strong acidic cation exchange resin. The filling height is 70%-80% of the tank height. The hard resin removal device is provided with a water inlet, a water outlet, a regeneration liquid inlet and a regeneration liquid outlet. The water inlet is located at the top of the hard resin removal device, so that the washing water passes through the resin layer from top to bottom. The water outlet is located at the bottom of the hard resin removal device, and the water after hardness removal flows out from here. The regeneration liquid inlet and the regeneration liquid outlet are respectively located at the top and the bottom of the hard resin removal device, and are used to introduce and discharge the regeneration liquid during resin regeneration. The self-cleaning filter has a shell made of stainless steel 316L, and the internal filter is a stainless steel woven mesh with a filtration accuracy of 30-60μm. It is equipped with a water inlet, a water outlet and a sewage outlet. A cleaning brush is installed on the inside of the filter. When the pressure difference between the inside and outside of the filter reaches the set value, the automatic control system starts the cleaning program. The cleaning brush cleans the filter under the drive of the motor, and the backwash water discharges impurities at the same time. A bipolar membrane device, which is composed of a bipolar membrane group, electrodes, a partition and a frame. The bipolar membrane group is composed of a plurality of bipolar membranes arranged in sequence, each bipolar membrane is separated by a partition to form an independent water flow channel. The bipolar membrane adopts a composite membrane material, and the electrode adopts a titanium-coated ruthenium electrode. The bipolar membrane device is provided with a water inlet, a concentrated water outlet, a fresh water outlet, a sodium hydroxide outlet and a hydrochloric acid outlet. The sodium chloride solution is converted by the action of an electric field to produce sodium hydroxide and hydrochloric acid, which are discharged from the corresponding outlets respectively. The condensed water recovery device includes a water collection tank, a filter and a sterilizer. The water collection tank is made of stainless steel and is used to collect the condensed water generated by the bipolar membrane device. The filter has a filtration accuracy of 5-10 μm and further removes tiny particle impurities in the condensed water. The sterilizer is an ultraviolet sterilizer, which uses the bactericidal effect of ultraviolet rays to kill bacteria and microorganisms in the condensed water. The acid-base separation and treatment device includes a sodium hydroxide evaporation and concentration system and a hydrochloric acid storage and preparation system. The sodium hydroxide evaporation and concentration system uses a triple-effect evaporator to concentrate an 8% sodium hydroxide solution to 32% through multiple evaporations and condensations. The hydrochloric acid storage and preparation system consists of a hydrochloric acid storage tank and a preparation device. The hydrochloric acid storage tank is made of corrosion-resistant plastic material and is used to store 7% hydrochloric acid produced by a bipolar membrane device. The automatic control system adopts a programmable logic controller as a core control unit, and also includes a pressure sensor and a flow sensor arranged on the water inlet pipe of the multi-media filter for monitoring the pressure and flow of the inlet water, a water quality sensor arranged at the water outlet end of the hard resin removal device for monitoring the calcium and magnesium ion content of the outlet water, a pressure difference sensor and a time sensor arranged on both sides of the filter screen of the self-cleaning filter for monitoring the pressure difference inside and outside the filter screen and the running time; a voltage sensor, a current sensor, a temperature sensor and a concentration sensor are installed in the bipolar membrane device for monitoring the electric field strength, current, solution temperature and solution concentration parameters. The control unit automatically controls the start and stop of the system, the opening and closing of the valve and the dosing operation according to the preset program and the collected parameters.

6. A resource-based washing water treatment system for sodium chloride high-salt wastewater according to claim 5, characterized in that: The multi-media filter is connected to the hard resin removal device through a corrosion-resistant pipe, and a flow regulating valve is provided on the corrosion-resistant pipe to adjust the water flow rate according to the treated water volume and water quality.

7. A resource-based washing water treatment system for sodium chloride high-salt wastewater according to claim 5, characterized in that: A water quality monitor is installed on the connecting pipe between the hardness removal resin device and the self-cleaning filter to monitor the water quality of the hardness removal water in real time. If the water quality does not meet the standard, the water will be returned to the hardness removal resin device for secondary treatment.

8. A resource-based washing water treatment system for sodium chloride high-salt wastewater according to claim 5, characterized in that: A pressure buffer tank is provided on the pipeline between the self-cleaning filter and the bipolar membrane device to stabilize the water pressure entering the bipolar membrane device.

9. A resource-based washing water treatment system for sodium chloride high-salt wastewater according to claim 5, characterized in that: A return pipe is provided between the concentrated water outlet of the bipolar membrane device and the water inlet of the multi-media filter, and part of the concentrated water can be returned to the multi-media filter for further treatment.

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