Multi-water-source coupling application method for wastewater reuse

Abstract

The invention belongs to the technical field of industrial sewage treatment, and provides a multi-water-source coupling application method for wastewater reuse, which comprises the following steps: balancing municipal sewage multi-point introduction load, blending reclaimed water with new water, online cleaning and ultrafiltration during immersion, online cleaning of a reverse osmosis membrane and online sterilization of the reverse osmosis membrane. The application of the method relieves the restriction of water resource shortage on sustainable development of companies; meanwhile, the situations of shortage of urban water resources and serious water area pollution can be relieved, co-fusion development of cities and enterprises is achieved, a new sustainable development way is developed for green development of iron and steel enterprises and comprehensive utilization of water resources, and wide popularization prospects and profound social significance are achieved.

Description

Technical Field

[0001] This invention belongs to the field of industrial wastewater treatment technology, specifically relating to municipal wastewater entering enterprises, and is a multi-source coupled application method for wastewater reuse. Background Technology

[0002] In recent years, the company has carried out large-scale process transformation and technological innovation. With the rapid development of the main steel production capacity, water shortage has constrained the company's high-speed development. In order to conserve water resources, municipal sewage will be introduced into the enterprise, and the amount of municipal sewage and appropriately purified reclaimed water will be increased to improve utilization efficiency. This will not only meet the company's production development and water conservation and emission reduction needs, but also alleviate the pressure on urban municipal sewage treatment. Summary of the Invention

[0003] The purpose of this invention is to provide a multi-source coupling application method for wastewater reuse, which can improve wastewater utilization efficiency and solve the technical problems of wastewater deterioration and overload after changes in water sources, and water source imbalance.

[0004] The technical solution adopted by the present invention to achieve the above objectives is as follows: A multi-source coupling application method for wastewater reuse includes: S1. Balance the load of multiple municipal sewage inflow points; S11. Analyze the water volume of each pumping station, and preliminarily determine the sewage introduction method through water source and water volume analysis; S12. Set the mode for adjusting the introduction of supplementary water source; S13. By optimizing the pipeline network of the newly built pumping stations and adding flow and liquid level interlocking control systems to each pumping station, the sewage intake of each pumping station is balanced.

[0005] S2, reclaimed water mixed with fresh water; S21. Reclaimed water is given priority for use in processes where inferior water quality can be used, and the remainder is sent to the industrial fresh water system; S22. Add an online turbidity meter to the reclaimed water pipeline. When the rainy season or the process control of the sewage treatment plant fails to meet the standards and the effluent does not meet the standards, the reclaimed water enters the three-membrane pretreatment through the valve to prepare demineralized water. S23. The chloride content in the reclaimed water is higher than that in the industrial fresh water. Chloride water quality monitoring is added to the industrial fresh water system. A mathematical model is established based on the chloride value. An electric regulating valve is added to the three-membrane inlet. All reclaimed water and river water are introduced. By adjusting the three-membrane inlet flow, the industrial fresh water control indicators are met. S3. Clean the ultrafiltration filter online during immersion; By employing enhanced air scrubbing, cleaning circulation, and alternating soaking cleaning, process control standards were established, and cleaning agents were used to improve the cleaning effect; S4. Online cleaning of reverse osmosis membrane; S5. Online sterilization method for reverse osmosis membranes.

[0006] Furthermore, the specific steps of S3 include: S31, air scrubbing for 3 minutes; S32. Perform a backwash once according to the ultrafiltration backwashing procedure; S33. After draining, perform a second air scrub for 1 minute, then backwash once. S34. After drainage is completed, alkaline washing is performed. The alkaline washing agent consists of 0.06% NaOH and 0.3% NaClO added simultaneously. The temperature is maintained at 35℃-38℃ and the pH is maintained at 12. Circulation washing is performed, with the agent circulation pump turned on and the flow rate maintained at 110-120 m3. The ultrafiltration cleaning return valve is closed, and air wiping is performed every 10 minutes for 10 seconds each time to strengthen the cleaning of fouling in the membrane pores. S35. After alkaline washing is completed, turn off the cleaning circulating water pump and let it stand and soak for 60 minutes (the soaking time can be extended according to the degree of dirt blockage). After soaking, perform air scrubbing again with an air pressure of 1.5 bar. Inhale for 8 seconds and stop for 15 seconds; inhale for 8 seconds and stop for 15 seconds, and repeat 10 times. S36. Perform a second cycle cleaning following the same steps as the first cycle. Time: 60 minutes. After cleaning, drain the wastewater from the ultrafiltration system. Empty the cleaning tank and pipelines, and rinse them thoroughly with clean water. S37. Use 0.5% HCl solution for acid pickling cleaning in a circulating manner for 30 minutes, and perform air wiping for 15 seconds every 10 minutes, while maintaining the temperature at 35℃-38℃. S38. After pickling, turn off the cleaning circulating water pump and let it soak for 60 minutes. The soaking time can be extended depending on the degree of fouling of the equipment. After soaking, perform air wiping again at a pressure of 1.5 bar. Inflate for 8 seconds, stop for 15 seconds, then inflate for 8 seconds and stop for 15 seconds. Repeat this cycle approximately 10 times. S39. Perform a second cleaning cycle following the steps of the first cycle. Duration: 30 minutes. Check the reagent concentration every 10 minutes throughout the cleaning process; add more reagent if necessary. Check the hardness at the start of cleaning and every 30 minutes, ensuring the hardness remains constant.

[0007] Furthermore, the specific steps of S4 include: S41. The process of first alkali washing and then acid washing is adopted. First, alkali is used to remove microorganisms on the membrane surface to reduce the encapsulation effect of microorganisms on hardness. Then, acid is used to clean hardness contamination, making the cleaning more targeted. S42. First, use alkali and dodecane to clean and remove suspended matter from the surface. If bacterial contamination is severe, use a bactericide for cyclic sterilization, and then use alkali and chemical agent for cyclic soaking and cleaning. This enhances the cleaning effect and saves cleaning agents. S43. The criteria for judging the cleaning effect are: pressure difference below 0.25MPa, product water pressure alkaline washing reaches 34KPa, and acid washing reaches 60KPa. This can ensure that the various performance indicators of the membrane element are restored to the design specifications after cleaning. S44, temperature 36-38℃, alkaline washing pH controlled 11.5-12, acid washing pH controlled 1.8-2.5, pressure difference controlled below 0.25MPa.

[0008] Furthermore, the specific steps of S5 include: Two metering tanks were used to hold liquid non-oxidizing bactericides DBNPA and isothiazolinone, respectively, for alternating sterilization. The sterilization process involved one DBNPA treatment followed by two isothiazolinone treatments. When the average temperature was above 25 degrees Celsius, the bactericide was added every 2-3 days. When the average temperature was below 25 degrees Celsius, the bactericide was added every 3-5 days.

[0009] Furthermore, DBNPA was used for sterilization, with an effective concentration of 200-500 mg / L and a duration of 2-4 hours; isothiazolinone was used, with an effective concentration of 150-300 mg / L and a duration of 1-2 hours.

[0010] The beneficial effects of this invention are: The application of the method of this invention increases the amount of municipal sewage and reclaimed water introduced into the company, significantly reduces the amount of fresh water introduced, and alleviates the constraints of water shortage on the company's sustainable development. At the same time, the application of the method of this invention can also alleviate the situation of urban water shortage and serious water pollution, realize the integrated development of cities and enterprises, and pave a new path for sustainable development of green development and comprehensive utilization of water resources for steel enterprises. It has broad prospects for promotion and far-reaching social significance. Detailed Implementation

[0011] The present invention will be further described below with reference to embodiments: Example

[0012] Taking the solution to the water volume imbalance caused by the company's multi-point sewage introduction method (including sewage from the North Suburbs, North Central Ring Road, Datong Road, etc.) as an example: Design a multi-source coupling application method for wastewater reuse, including: S1. Balance the load of multiple municipal sewage inflow points; First, we analyze the water volume and source of each pumping station. For example, the actual water volume of the steel enterprise is about 0.5 million tons / day, the water volume of the North Suburb is about 10,000 tons / day, and the water volume of the No. 2 sewage pumping station on the North Central Ring Road is relatively large, ranging from 15,000 tons to 25,000 tons / day. Its untreated sewage can be sent to the downstream municipal sewage treatment plant. Then, through analysis of water sources and water volume, the preliminary method of sewage introduction was determined: all sewage will be introduced from Jiancaoping, steel enterprises, and the remaining municipal sewage in the northern suburbs; at the same time, the North Central Ring Pumping Station will be used as the introduction mode for regulating and supplementing water sources. Furthermore, by optimizing the pipeline network of the newly built pumping stations and adding flow and level interlocking control systems to each pumping station, the amount of sewage introduced can be balanced.

[0013] S2, Reclaimed Water Mixed with Fresh Water S21. The water quality of the North Suburb Reclaimed Water is worse than that of the Fenhe River and demineralized water. By improving the water inlet pipeline network, the North Suburb Reclaimed Water can be prioritized for use in the power generation cooling tower spraying process, and in processes such as the 600-ton demineralized water station that can use inferior water. The remainder will enter the industrial fresh water system. S22. Add an online turbidity meter to the reclaimed water pipeline. When the effluent fails to meet the standards due to rainy season or process control issues at the North Suburb Wastewater Treatment Plant, the reclaimed water will enter the triple membrane pretreatment system through a valve to prepare demineralized water. S23. The chloride content in the reclaimed water in the northern suburbs is higher than the industrial fresh water standard. Chloride water quality monitoring will be added to the industrial fresh water system. A mathematical model will be established based on the chloride value. An electric regulating valve will be added to the three-membrane inlet to introduce all reclaimed water and Fenhe River water. By adjusting the three-membrane inlet flow, the industrial fresh water control standard will be achieved.

[0014] S3. Clean the ultrafiltration filter online during immersion; By employing enhanced air scrubbing, cleaning circulation, and alternating soaking cleaning, process control standards were established. In particular, the use of self-prepared cleaning agents effectively improved the cleaning effect. The specific steps are as follows: S31, air scrubbing for 3 minutes; S32. Perform a backwash once according to the ultrafiltration backwashing procedure; S33. After draining, perform a second air scrub for 1 minute, then backwash once. S34. After drainage is completed, alkaline washing is performed. The alkaline washing agent consists of 0.06% NaOH and 0.3% NaClO added simultaneously. The temperature is maintained at 35℃-38℃ and the pH is maintained at 12. Circulation washing is performed, with the agent circulation pump turned on and the flow rate maintained at 110-120 m3. The ultrafiltration cleaning return valve is closed, and air wiping is performed every 10 minutes for 10 seconds each time to strengthen the cleaning of fouling in the membrane pores. S35. After alkaline washing is completed, turn off the cleaning circulating water pump and let it stand and soak for 60 minutes (the soaking time can be extended according to the degree of dirt blockage). After soaking, perform air scrubbing again with an air pressure of 1.5 bar. Inhale for 8 seconds and stop for 15 seconds; inhale for 8 seconds and stop for 15 seconds, and repeat 10 times. S36. Perform a second cycle cleaning following the same steps as the first cycle; time: 60 minutes. After cleaning, drain the wastewater from the ultrafiltration system. Empty the cleaning tank and pipelines, and rinse them thoroughly with clean water. S37. Use 0.5% HCl solution for acid pickling cleaning in a circulating manner for 30 minutes, and perform air wiping for 15 seconds every 10 minutes, while maintaining the temperature at 35℃-38℃. S38. After pickling, turn off the cleaning circulating water pump and let it soak for 60 minutes. The soaking time can be extended depending on the degree of fouling of the equipment. After soaking, perform air wiping again at a pressure of 1.5 bar. Inflate for 8 seconds, stop for 15 seconds, then inflate for 8 seconds and stop for 15 seconds. Repeat this cycle approximately 10 times. S39. Perform a second cleaning cycle following the steps of the first cycle. Duration: 30 minutes. Check the reagent concentration every 10 minutes throughout the cleaning process; add more reagent if necessary. Check the hardness at the start of cleaning and every 30 minutes, ensuring the hardness remains constant.

[0015] S4. Online cleaning of reverse osmosis membrane; S41. The process of first alkali washing and then acid washing is adopted. First, alkali is used to remove microorganisms on the membrane surface to reduce the encapsulation effect of microorganisms on hardness. Then, acid is used to clean hardness contamination, making the cleaning more targeted. S42. First, use alkali and dodecane to clean and remove suspended matter from the surface. If bacterial contamination is severe, use a bactericide for cyclic sterilization, and then use alkali and chemical agent for cyclic soaking and cleaning. This enhances the cleaning effect and saves cleaning agents. S43. The criteria for judging the cleaning effect are: pressure difference below 0.25MPa, product water pressure alkaline washing reaches 34KPa, and acid washing reaches 60KPa. This can ensure that the various performance indicators of the membrane element are restored to the design specifications after cleaning. S44, temperature 36-38℃, alkaline washing pH controlled 11.5-12, acid washing pH controlled 1.8-2.5, pressure difference controlled below 0.25MPa.

[0016] S5. Online sterilization method for reverse osmosis membranes; Two metering tanks were used to hold liquid non-oxidizing bactericides DBNPA (2,2-dibromo-3-nitropropionamide) and isothiazolinone (5-chloro-2-methyl-4-isothiazolin-3-one / 2-methyl-4-isothiazolin-3-one) respectively for alternating sterilization. The sterilization was carried out cyclically, with one DBNPA sterilization followed by two isothiazolinone sterilizations. When the average temperature was above 25°C, the bactericide was added once every 2-3 days, and when the average temperature was below 25°C, the bactericide was added once every 3-5 days.

[0017] DBNPA was used for sterilization, with an effective concentration of 200-500 mg / L and a duration of 2-4 hours. Isothiazolinone was used, with an effective concentration of 150-300 mg / L, and the duration was 1-2 hours. Reverse osmosis (RO) online sterilization system, including: (1) Two non-oxidizing bactericide metering tanks: each with a volume of 1m3, made of FRP (fiber reinforced plastic). The non-oxidizing bactericide metering tanks are equipped with the following connection ports: liquid outlet, drain outlet, level gauge interface, dosing port, dilution water interface, drain valve return port, as well as water inlet valve, drain valve, air valve, and liquid inlet valve. All valves are made of UPVC. The metering tanks are also equipped with magnetic level gauges with remote transmission function, which can output 4-20mA signals; (2) Two non-oxidizing bactericide metering pumps: (Q=170L / h, H=7bar, 0.25KW) Each metering pump outlet is equipped with a ball check valve and a pressure relief valve (safety valve). A pipeline filter is installed at the metering pump inlet. A corrosion-resistant pressure gauge is installed on the metering pump outlet pipeline, and an isolation device and damper are added; (3) Dosing pipeline: The metering outlet main pipe is branched to the water inlet pipe of each reverse osmosis security filter and valves are installed. This allows for selective sterilization of a single set or multiple sets simultaneously, depending on the degree of microbial contamination of the reverse osmosis membrane unit. This facilitates the control and elimination of reverse osmosis microbial contamination and sterilization of the corresponding security filter membrane elements, preventing microorganisms from multiplying on the security filter membrane elements and thus contaminating the reverse osmosis membrane. (4) All metal and non-metal parts that come into contact with the drug solution are made of materials that are resistant to the corrosion of the corresponding drug solution, and all pipelines are made of UPVC pipe.

Claims

1. A multi-source coupling application method for wastewater reuse, characterized in that: include: S1. Balance the load of multiple municipal sewage inflow points; S11. Analyze the water volume of each pumping station, and preliminarily determine the sewage introduction method through water source and water volume analysis; S12. Set the mode for adjusting the introduction of supplementary water source; S13. By optimizing the pipeline network of the newly built pumping stations, and adding flow and liquid level interlocking control systems to each pumping station, the sewage inflow of each pumping station is balanced. S2, reclaimed water mixed with fresh water; S21. Reclaimed water is given priority for use in processes where inferior water quality can be used, and the remainder is sent to the industrial fresh water system; S22. Add an online turbidity meter to the reclaimed water pipeline. When the rainy season or the process control of the sewage treatment plant fails to meet the standards and the effluent does not meet the standards, the reclaimed water enters the three-membrane pretreatment through the valve to prepare demineralized water. S23. The chloride content in the reclaimed water is higher than that in the industrial fresh water. Chloride water quality monitoring is added to the industrial fresh water system. A mathematical model is established based on the chloride value. An electric regulating valve is added to the three-membrane inlet. All reclaimed water and river water are introduced. By adjusting the three-membrane inlet flow, the industrial fresh water control indicators are met. S3. Online cleaning of ultrafiltration during immersion; employing enhanced air scrubbing, cleaning circulation, and alternating immersion cleaning, and using cleaning agents to improve the cleaning effect; S4. Online cleaning of reverse osmosis membrane; S5. Online sterilization of reverse osmosis membrane.

2. The multi-source coupling application method for wastewater reuse according to claim 1, characterized in that: The specific steps of S3 include: S31, air scrubbing for 3 minutes; S32. Perform a backwash once according to the ultrafiltration backwashing procedure; S33. After draining, perform a second air scrub for 1 minute, then backwash once. S34. After drainage is completed, alkaline washing is performed. The alkaline washing agent consists of 0.06% NaOH and 0.3% NaClO added simultaneously. The temperature is maintained at 35℃-38℃ and the pH is maintained at 12. Circulation washing is performed, with the agent circulation pump turned on and the flow rate maintained at 110-120 m3. The ultrafiltration cleaning return valve is closed, and air wiping is performed every 10 minutes for 10 seconds each time to strengthen the cleaning of fouling in the membrane pores. S35. After alkaline washing is completed, turn off the cleaning circulating water pump and let it stand and soak for 60 minutes. After soaking, perform air scrubbing again with an air pressure of 1.5 bar. Inhale for 8 seconds and stop for 15 seconds; inhale for 8 seconds and stop for 15 seconds, and repeat 10 times. S36. Repeat the above steps for a second cleaning cycle, which takes 60 minutes. After cleaning, drain the wastewater inside the ultrafiltration system, empty the cleaning water tank and pipelines, and rinse them with clean water. S37. Use 0.5% HCl solution for acid pickling cleaning in a circulating manner for 30 minutes, and perform air wiping for 15 seconds every 10 minutes, while maintaining the temperature at 35℃-38℃. S38. After pickling, turn off the cleaning circulating water pump and let it soak for 60 minutes. After soaking, perform air wiping again at a pressure of 1.5 bar. Inflate for 8 seconds, stop for 15 seconds, then inflate for 8 seconds, stop for 15 seconds. Repeat this cycle approximately 10 times. S39. Perform the above-mentioned cycle cleaning again for 30 minutes. During the entire cleaning process, check the agent concentration every 10 minutes. If the concentration is not up to standard, add more agent in time. Check the hardness every 30 minutes after starting the cleaning process, and keep the hardness constant.

3. The multi-source coupling application method for wastewater reuse according to claim 1, characterized in that: The specific steps of S4 include: S41. The process of first alkali washing and then acid washing is adopted. First, alkali is used to remove microorganisms on the membrane surface to reduce the encapsulation effect of microorganisms on hardness. Then, acid is used to clean hardness contamination, making the cleaning more targeted. S42. First, use alkali and dodecane to clean and remove suspended matter from the surface. If bacterial contamination is severe, use a bactericide for cyclic sterilization, and then use alkali and chemical agent for cyclic soaking and cleaning. This enhances the cleaning effect and saves cleaning agents. S43. The criteria for judging the cleaning effect are: pressure difference below 0.25MPa, product water pressure alkaline washing reaches 34KPa, and acid washing reaches 60KPa. This can ensure that the various performance indicators of the membrane element are restored to the design specifications after cleaning. S44, temperature 36-38℃, alkaline washing pH controlled 11.5-12, acid washing pH controlled 1.8-2.5, pressure difference controlled below 0.25 MPa.

4. The multi-source coupling application method for wastewater reuse according to claim 1, characterized in that: The specific steps of S5 include: Two metering tanks were used to hold liquid non-oxidizing bactericides DBNPA and isothiazolinone, respectively, for alternating sterilization. The sterilization process involved one DBNPA treatment followed by two isothiazolinone treatments. When the average temperature was above 25 degrees Celsius, the bactericide was added every 2-3 days. When the average temperature was below 25 degrees Celsius, the bactericide was added every 3-5 days.

5. A multi-source coupling application method for wastewater reuse according to claim 4, characterized in that: The method employs DBNPA for sterilization, with an effective concentration of 200-500 mg / L and a duration of 2-4 hours; or isothiazolinone, with an effective concentration of 150-300 mg / L and a duration of 1-2 hours.