A method and treatment system for producing pure water by a double membrane method

Abstract

The application discloses a method for preparing pure water by a double membrane method, which comprises the following steps: Yangtze River raw water is introduced into a resin adsorption tower by a water inlet pump; the raw water has a conductivity of 234-395 muS / cm and a calcium ion of 11.9-14.2 mg / L; a carboxyl-modified phenolic resin is placed in the resin adsorption tower, and the carboxyl-modified phenolic resin accounts for 75-85% of the total volume of the resin adsorption tower; the residence time of the raw water in the resin adsorption tower is 27-41 min; the raw water treated above is introduced into a hollow fiber ultrafiltration membrane system, the pressure of the membrane is 0.1-0.3 MPa, the pure water flux is 2.1-3.4 t / h, and the working temperature of the membrane is 23-28 DEG C; the raw water treated by the ultrafiltration membrane is introduced into a two-stage reverse osmosis system, the water quality reaches the standard, and the prepared pure water is discharged into equipment requiring pure water by a water discharge pump. The pure water treatment method has the advantages of low production and operation cost, fully embodies the energy-saving and emission-reducing effect, and is an environment-friendly green production process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pure water preparation, in particular to a technology and method for purifying pure water. BACKGROUND

[0002] The water resources in the Yangtze River Basin are very rich. At present, the available amount of water resources in the Yangtze River Basin exceeds 200 billion cubic meters, but the utilization rate is low, only more than 20%. Therefore, the development and utilization of the Yangtze River raw water in many aspects is a direction worthy of in-depth study. The raw water in the lower reaches of the Yangtze River is complex. Due to local pollution, eutrophication and other reasons, the water quality is complex and variable, with high turbidity, high conductivity, high calcium ion content and other problems. Research on it can greatly develop the water resources in the lower reaches of the Yangtze River and promote the rational utilization of water resources.

[0003] Pure water refers to H2O without impurities. From an academic point of view, pure water, also known as high-purity water, refers to water with extremely high chemical purity, which is mainly used in biology, chemistry, chemical industry, metallurgy, space exploration, power and other fields, but the water quality purity requirement is quite high, for example, the pure water used in the power system requires low impurity content to reach the "microgram per liter" level. The conductivity of pure water is less than 10 μS / cm, and the calcium ion is less than 0.005 mg / L.

[0004] The research on the Yangtze River raw water can convert it into pure water that can be used, so as to better realize the resource utilization of the Yangtze River raw water. According to the water quality and quantity of the Yangtze River raw water, an economic and efficient treatment process is developed to actively respond to the increasingly stringent environmental protection regulations. SUMMARY

[0005] Therefore, the technical problem to be solved by the present application is to provide a method for preparing pure water from the Yangtze River raw water according to the water quality and quantity of the downstream Yangtze River raw water, so as to obtain high-quality pure water. Another technical problem to be solved by the present application is to provide a treatment system for implementing the treatment method.

[0006] The technical solution of the present application is a method for preparing pure water by double membrane method, comprising the following steps:

[0007] a. The raw water of the Yangtze River enters the resin adsorption tower through the water inlet pump; the raw water quality is that the conductivity is 234-395 μS / cm, and the calcium ion is 11.9-14.2 mg / L; the carboxyl-modified phenolic resin is placed in the resin adsorption tower, and the carboxyl-modified phenolic resin accounts for 75-85% of the total volume of the resin adsorption tower; the residence time of the raw water in the resin adsorption tower is 27-41 min; the preparation of the carboxyl-modified phenolic resin: formic acid and formaldehyde are prepared into a mixed solution according to a volume ratio of (1-3):1, the mixed solution is loaded into a reaction kettle, 135-192 g of phenoxyacetic acid, 3-72 mL of concentrated sulfuric acid and 23-25 mL of pyridine are added per liter of the mixed solution, then the reaction kettle is heated to 91-95 ℃ in a nitrogen protective atmosphere, and stirring is performed for more than 6 hours until the reaction is complete;

[0008] b. The raw water treated in the above step enters the hollow fiber ultrafiltration membrane system, the pressure of the membrane is 0.1-0.3 MPa, the pure water flux is 2.1-3.4 t / h, and the working temperature of the membrane is 23-28 ℃.

[0009] c. The raw water treated by the ultrafiltration membrane enters the two-stage reverse osmosis system, the water production rate is 80-88%, and the pressure is 1.4-3.2 MPa; after the two-stage reverse osmosis system, the water quality reaches the standard, and the prepared pure water is discharged into the equipment requiring pure water by the water discharge pump.

[0010] After the ultrafiltration membrane in step b, the SDI (sludge density index) of the raw water is 0.9-1.6.

[0011] After step c, the water quality of the reverse osmosis water is that the conductivity is 5-9 μS / cm, and the calcium ion is 0.001-0.002 mg / L.

[0012] According to the method for preparing pure water by the double membrane method, preferably, in step a, after the modified resin adsorption tower, the raw water quality is that the conductivity is 187-321 μS / cm, and the calcium ion is 0.2-0.6 mg / L.

[0013] According to the method for preparing pure water by the double membrane method, preferably, in step b, the cross-flow filtration mode is used; and the recovery rate of step b is 87-91%.

[0014] According to the method for preparing pure water by the double membrane method, preferably, the water production rate of step c is 80-87%.

[0015] According to the method for preparing pure water by a double membrane method, preferably, the preparation of the carboxyl-modified phenolic resin in step a is as follows: 1) formic acid and formaldehyde are prepared into a mixed solution according to a volume ratio of (1-3):1, the mixed solution is loaded into a reaction kettle, 135-192 g of phenoxyacetic acid, 3-72 mL of concentrated sulfuric acid and 23-25 mL of pyridine are added into the mixed solution according to a volume of 1 L, then the reaction kettle is heated to 91-95 ℃ under a nitrogen protection atmosphere, and stirring is performed for more than 6 hours until the reaction is completed; 2) after the reaction is completed, the mixture is cooled, filtered, and sequentially washed with petroleum ether and clean water to obtain a modified phenolic resin intermediate product; 3) the modified phenolic resin intermediate product is immersed in a 2-10% sodium chloride solution according to a solid-liquid ratio of 1:3-5, filtered at room temperature, and sequentially washed with petroleum ether and clean water; and 4) then the modified phenolic resin intermediate product is immersed in an ethanol solution according to a solid-liquid ratio of 1:3-5, Soxhlet extraction is performed for 4-10 hours to obtain a light yellow product, the light yellow product is sequentially washed with methanol and clean water, and vacuum drying is performed to obtain the carboxyl-modified phenolic resin.

[0016] The present application is directed to the water quality characteristics of the Yangtze River raw water, and a carboxyl-modified phenolic resin is developed and prepared for effectively removing calcium ions in the raw water.

[0017] According to the method for preparing pure water by a double membrane method, in the preparation of the carboxyl-modified phenolic resin, preferably, in step 1), the stirring time is 7-9 hours, and the stirring speed is 45-65 revolutions per minute; in step 2), the petroleum ether is washed for 3-5 times, and the clean water is washed for 3-5 times.

[0018] According to the method for preparing pure water by a double membrane method, in the preparation of the carboxyl-modified phenolic resin, preferably, in step 3), the mass concentration of the sodium chloride solution is 3-6%; the petroleum ether is washed for 3-5 times, and the clean water is washed for 3-5 times.

[0019] More preferably, in step 3), the mass concentration of the sodium chloride solution is 3-4%.

[0020] According to the method for preparing pure water by a double membrane method, in the preparation of the carboxyl-modified phenolic resin, preferably, in step 4), the light yellow product is washed with methanol for 3-4 times and with clean water for 3-4 times; and the vacuum drying temperature in step 4) is 55-75 ℃. More preferably, the vacuum drying temperature in step 4) is 60-70 ℃.

[0021] According to the method for preparing pure water by a double membrane method, in the preparation of the carboxyl-modified phenolic resin, preferably, the volume exchange capacity of the carboxyl-modified phenolic resin is 3.7-4.9 mmol / ml. The carboxyl-modified phenolic resin has a strong adsorption and displacement capacity for calcium ions.

[0022] The application further provides a treatment system used in the preparation method, which comprises a water inlet pump, a resin adsorption tower, modified resin fillers, a first-stage lifting pump, an ultrafiltration system, a high-pressure pump, a two-stage reverse osmosis system and a water outlet pump.

[0023] The ultrafiltration system is sequentially connected with the high-pressure pump, the two-stage reverse osmosis system and the water outlet pump.

[0024] The double-membrane method of the application refers to an ultrafiltration membrane and a reverse osmosis membrane.

[0025] The application provides a double-membrane method for preparing pure water, which can convert the Yangtze River raw water into pure water through simple treatment and effectively utilize the raw water resources. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The application provides a pure water preparation treatment system.

[0027] In the figure, the water inlet pump 1, the resin adsorption tower 2, the carboxyl-modified phenolic resin 3, the first-stage lifting pump 4, the ultrafiltration system 5, the high-pressure pump 6, the two-stage reverse osmosis system 7 and the water outlet pump 8. DETAILED DESCRIPTION

[0028] In order to better understand the application, the application will be further illustrated by examples, but the application is not limited to the examples.

[0029] The application will be described in detail below with reference to the drawings and examples.

[0030] Example 1

[0031] The application provides a pure water preparation treatment system, which comprises a water inlet pump, a resin adsorption tower, modified resin fillers, a first-stage lifting pump, an ultrafiltration system, a high-pressure pump, a two-stage reverse osmosis system and a water outlet pump.

[0032] The Yangtze River raw water is subjected to simple coagulation and sedimentation treatment, and the obtained Yangtze River raw water has a conductivity of 395 muS / cm and a calcium ion content of 14.2 mg / L.

[0033] The raw water is introduced into the resin adsorption tower through the water inlet pump. The carboxyl-modified phenolic resin is placed in the resin adsorption tower, and the carboxyl-modified phenolic resin accounts for 85% of the total volume of the resin adsorption tower. The residence time of the raw water in the resin adsorption tower is 41 min. After the modified resin adsorption tower, the raw water has a conductivity of 321 muS / cm and a calcium ion content of 0.6 mg / L.

[0034] The present application is directed to the water quality characteristics of raw water, in order to effectively remove calcium ions in raw water, a carboxyl-modified phenolic resin is developed. Preparation of the carboxyl-modified phenolic resin: 1) formic acid and formaldehyde are prepared into a mixed solution according to a volume ratio of 3:1, the mixed solution is loaded into a reaction kettle, 192g of phenoxyacetic acid, 69mL of concentrated sulfuric acid (mass ratio 98%) and 25mL of pyridine are added per liter of the mixed solution, then the reaction kettle is heated to 95°C in a nitrogen protective atmosphere, stirring for 9h at a stirring speed of 65r / min; 2) after the reaction is completed, the mixture is cooled, filtered, washed with petroleum ether for 5 times and with clean water for 5 times to obtain a modified phenolic resin intermediate product; 3) the modified phenolic resin intermediate product is immersed in a 4% sodium chloride solution at a solid-liquid ratio of 1:5 for 24h, filtered at room temperature, washed with petroleum ether for 5 times and with clean water for 5 times, then the modified phenolic resin intermediate product is immersed in an ethanol solution at a solid-liquid ratio of 1:5, Soxhlet extraction is performed for 10h to obtain a light yellow product, which is washed with methanol for 4 times and with clean water for 4 times, and then vacuum dried at 65°C to obtain the carboxyl-modified phenolic resin. The carboxyl-modified phenolic resin has a volume exchange capacity of 4.9mmol / ml, and has a strong adsorption displacement capacity for calcium ions.

[0035] Subsequently, the raw water enters the hollow fiber ultrafiltration membrane system, the pressure of the membrane is 0.3MPa, the pure water flux is 3.4t / h, the cross-flow filtration mode is adopted, the recovery rate is 91%, and the working temperature of the membrane is 28°C. After the ultrafiltration membrane, the SDI (sludge density index) of the raw water is 0.9.

[0036] The raw water treated by the ultrafiltration membrane enters the two-stage reverse osmosis system, the water production rate is between 87%, and the pressure is 3.2MPa. After the two-stage reverse osmosis system, the water quality of the reverse osmosis product water is that the conductivity is 9μS / cm, and the calcium ion is 0.002mg / L.

[0037] The prepared pure water is discharged into the equipment requiring pure water by the drainage pump.

[0038] Example 2

[0039] A pure water preparation and treatment system, comprising a water inlet pump, a resin adsorption tower, modified resin fillers, a primary booster pump, an ultrafiltration system, a high-pressure pump, a two-stage reverse osmosis system, and a drainage pump.

[0040] The Yangtze River raw water is treated by simple coagulation and sedimentation to obtain the Yangtze River raw water with a water quality of conductivity of 256μS / cm and calcium ion of 12.3mg / L.

[0041] The raw water enters the resin adsorption tower through the water inlet pump. The carboxyl-modified phenolic resin is placed in the resin adsorption tower, and the carboxyl-modified phenolic resin accounts for 80% of the total volume of the resin adsorption tower. The residence time of the raw water in the resin adsorption tower is 35 min. After passing through the modified resin adsorption tower, the raw water has a water quality of conductivity of 211 μS / cm and calcium ion of 0.3 mg / L.

[0042] According to the water quality characteristics of the raw water, in order to effectively remove the calcium ions in the raw water, the carboxyl-modified phenolic resin is developed and prepared. The preparation of the carboxyl-modified phenolic resin: 1) formic acid and formaldehyde are prepared into a mixed solution according to a volume ratio of 2:1, the mixed solution is loaded into a reaction kettle, 145 g of phenoxyacetic acid, 17 mL of concentrated sulfuric acid (mass ratio 98%) and 23 mL of pyridine are added per liter of mixed solution, then the reaction kettle is heated to 91°C in a nitrogen protection atmosphere, and stirred at a speed of 45 revolutions / min for 7 h;

[0043] 2) After the reaction is completed, the mixture is cooled, filtered, washed with petroleum ether 3 times, and washed with clean water 3 times to obtain a modified phenolic resin intermediate product; 3) the modified phenolic resin intermediate product is immersed in a 3% sodium chloride solution at a solid-liquid ratio of 1:3 for 20 h, filtered at room temperature, washed with petroleum ether 3 times, and washed with clean water 3 times, then the modified phenolic resin intermediate product is soaked in an ethanol solution at a solid-liquid ratio of 1:3, and is Soxhlet extracted for 4 h to obtain a light yellow product, which is washed with methanol 3 times and clean water 3 times, and is dried at 65°C under vacuum to obtain the carboxyl-modified phenolic resin. The volume exchange capacity of the carboxyl-modified phenolic resin is 4.1 mmol / ml, and it has a strong adsorption displacement capacity for calcium ions.

[0044] Subsequently, the raw water enters the hollow fiber ultrafiltration membrane system, the membrane pressure is 0.2 MPa, the pure water flux is 2.5 t / h, the cross-flow filtration mode is adopted, the recovery rate is 88%, and the membrane working temperature is 25°C. After passing through the ultrafiltration membrane, the SDI (sludge density index) of the raw water is 1.3.

[0045] The raw water treated by the ultrafiltration membrane enters the two-stage reverse osmosis system, the water production rate is between 83%, and the pressure is between 1.9 MPa. After passing through the two-stage reverse osmosis system, the water quality of the reverse osmosis product water is conductivity of 7 μS / cm and calcium ion of 0.002 mg / L.

[0046] The prepared pure water is discharged into the equipment requiring pure water through the water discharge pump.

[0047] Of course, those skilled in the art should recognize that the above embodiments are only used to illustrate the present application, and are not used as a limitation on the present application, as long as the transformation and deformation of the above embodiments are within the scope of the spirit of the present application.

Claims

1. A method for producing pure water by a double membrane process, characterized by: It comprises the following steps: a. The raw water of the Yangtze River enters the resin adsorption tower through the water inlet pump; the raw water quality is that the conductivity is 234-395 µS / cm, and the calcium ion is 11.9-14.2 mg / L; the carboxyl modified phenolic resin is placed in the resin adsorption tower, and the carboxyl modified phenolic resin accounts for 75-85% of the total volume of the resin adsorption tower; the residence time of the raw water in the resin adsorption tower is 27-41 min; The preparation of the carboxyl modified phenolic resin: 1) formic acid and formaldehyde are prepared into a mixed solution according to the volume ratio (1-3):1, the mixed solution is loaded into a reaction kettle, 135-192 g of phenoxyacetic acid, 3-72 mL of concentrated sulfuric acid and 23-25 mL of pyridine are added per liter of the mixed solution, then the reaction kettle is heated to 91-95℃ in a nitrogen protection atmosphere, and stirred for more than 6 hours until the reaction is complete; 2) after the reaction is completed, the mixture is cooled, filtered, and washed with petroleum ether and water in sequence to obtain the modified phenolic resin intermediate product; 3) the modified phenolic resin intermediate product is immersed in a 2-10% sodium chloride solution at a solid-liquid ratio of 1:3-5 for 18-24 h, filtered at room temperature, and washed with petroleum ether and water in sequence; 4) then the modified phenolic resin intermediate product is soaked in an ethanol solution at a solid-liquid ratio of 1:3-5, and Soxhlet extraction is performed for 4-10 h to obtain a light yellow product, which is washed with methanol and water in sequence, and then vacuum dried to obtain the carboxyl modified phenolic resin; the volume exchange capacity of the carboxyl modified phenolic resin is 3.7-4.9 mmol / ml; it has strong adsorption and displacement capacity for calcium ions; After passing through the modified resin adsorption tower, the raw water quality is that the conductivity is 187-321 µS / cm, and the calcium ion is 0.2-0.6 mg / L; b. The raw water treated in the above step enters the hollow fiber ultrafiltration membrane system, the membrane pressure is 0.1-0.3 MPa, the pure water flux is 2.1-3.4 t / h, and the membrane working temperature is 23-28℃; c. The raw water treated by the ultrafiltration membrane enters the two-stage reverse osmosis system, the water production rate is between 80-88%, and the pressure is between 1.4-3.2 MPa; after passing through the two-stage reverse osmosis system, the water quality meets the standard, and the prepared pure water is discharged into the equipment that needs pure water by the drainage pump.

2. A method of producing pure water by a double membrane process according to claim 1, characterized by: Step b adopts cross-flow filtration mode; the recovery rate of step b is 87-91%.

3. A method of producing pure water by a double membrane process according to claim 1, characterized by: The water production rate of step c is between 80-87%.

4. A method of producing pure water by a double membrane process according to claim 1, characterized by: In step 1, the stirring time is 7-9 h; the stirring speed is 45-65 r / min; in step 2, the petroleum ether is washed for 3-5 times; and the water is washed for 3-5 times.

5. A method of producing pure water by a double membrane process according to claim 1, characterized by: In step 3, the mass concentration of the sodium chloride solution is 3-6%; in step 3, the petroleum ether is washed for 3-5 times; and the water is washed for 3-5 times.

6. A method of producing pure water by a double membrane process according to claim 1, characterized by: In step 4, the light yellow product is washed with methanol for 3-4 times and water for 3-4 times; in step 4, the vacuum drying temperature is 55-75℃.

7. A treatment system for carrying out the method of claim 1 for the production of pure water, characterized in that: It comprises a water inlet pump, a resin adsorption tower, modified resin filler, a first-stage lifting pump, an ultrafiltration system, a high-pressure pump, a two-stage reverse osmosis system and a drainage pump; the resin adsorption tower is internally provided with modified resin filler, which is the carboxyl-modified phenolic resin according to claim 1; the outlet of the resin adsorption tower is sequentially connected with the first-stage lifting pump and the ultrafiltration system. The ultrafiltration system is sequentially connected with the high-pressure pump, the two-stage reverse osmosis system and the drainage pump.

Images