An industrial wastewater zero discharge treatment process

Abstract

The application discloses an industrial wastewater zero-discharge treatment process and relates to the technical field of industrial wastewater treatment. The application adopts a combined process of "air flotation+softening precipitation+catalytic oxidation+multi-medium filtration+ultrafiltration+DTRO+RO" to concentrate wastewater, and the concentrated water of the DTRO is treated through a process of "softening precipitation+multi-medium filtration+evaporation crystallization". Meanwhile, a modified monomer is generated through an imino nucleophilic acyl substitution reaction of maleic anhydride and diethyl iminodiacetate, and the modified monomer is acidified by hydrochloric acid to obtain an acidified modified monomer containing a large amount of carboxyl groups; then, the acidified modified monomer is subjected to a free radical polymerization method together with hydroxyethyl methacrylate and 2-acrylamido-2-methylpropanesulfonic acid sodium to obtain an oily copolymer; and finally, the copolymer is adsorbed by porous ceramic particles, the surface of the particles is sprayed with aluminum dihydrogen tripolyphosphate encapsulation, and a final silicon removal agent is formed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of industrial wastewater treatment, in particular to an industrial wastewater zero discharge treatment process. BACKGROUND

[0002] The main pollutants in shale gas fracturing flowback fluid and wastewater are COD, SS, calcium ions, magnesium ions, barium ions, hardness, chloride ions, TDS, polyacrylamide, etc., which have the following characteristics: high difficulty in removing organic matter concentration, complex composition of residual organic matter in wastewater, higher concentration after concentration by membrane system, improper design may cause serious membrane system pollution and frequent cleaning; high salt content, fracturing flowback fluid contains a large amount of chemical additives, which are complex in composition, high in mineralization degree and salinity, and higher in TDS after concentration by membrane system, which has certain requirements for the pressure resistance grade of the membrane system; high hardness, the hardness of the wastewater is extremely high and needs to be softened and removed.

[0003] Therefore, the present application adopts nucleophilic acyl substitution reaction of imino of maleic anhydride and iminodiacetic acid diethyl ester to generate a modified monomer, and then acidifies the modified monomer with hydrochloric acid to obtain an acidified modified monomer containing a large amount of carboxyl groups. Subsequently, the acidified modified monomer is used to prepare an oily copolymer with hydroxyethyl methacrylate and 2-acrylamido-2-methylpropanesulfonic acid sodium by a free radical polymerization method. Then, the oily copolymer is adsorbed by porous ceramic particles with high specific surface area and porous structure, and finally, the surface of the particles is sprayed with aluminum dihydrogen tripolyphosphate for encapsulation to form the final silicon removal agent. The scheme realizes efficient and stable silicon removal by precisely designing the structure of the monomer, controlling the copolymerization ratio, combining carrier adsorption and encapsulation technology. SUMMARY

[0004] The present application aims to provide an industrial wastewater zero discharge treatment process to solve the problems in the prior art.

[0005] To solve the above technical problems, the present application provides the following technical scheme:

[0006] An industrial wastewater zero discharge treatment process, comprising the following steps:

[0007] The fracturing flowback fluid is subjected to preliminary adjustment, a materialization system, a biochemical system, an ultrafiltration system, a DTRO system, an energy-saving evaporation system and a liquid solidification machine system to realize zero discharge and meet the environmental protection requirements for wastewater disposal;

[0008] The biochemical system is added with a silicon removal agent, wherein the silicon removal agent is an oily copolymer prepared by a free radical polymerization method with hydroxyethyl methacrylate, 2-acrylamido-2-methylpropanesulfonic acid sodium and acidified modified monomers in a mass ratio of 1:1:2.4-2.8, and the oily copolymer is adsorbed by porous ceramic particles and encapsulated on the surface by spraying aluminum dihydrogen tripolyphosphate;

[0009] The acidified modified monomer is prepared by acidifying the modified monomer with hydrochloric acid, wherein the modified monomer is formed by nucleophilic acyl substitution reaction of imino group in diethyl iminodiacetate with maleic anhydride.

[0010] As an optimization, the silicon removal agent comprises the following preparation steps:

[0011] S1, the silicon removal agent comprises the following preparation steps: taking hydroxyethyl methacrylate, 2-acrylamido-2-methylpropane sulfonic acid sodium and acidified modified monomer as polymerization monomers according to a mass ratio of 1:1:2.4-2.8, adding deionized water in an amount of 2-4 times the mass of the polymerization monomers, stirring uniformly, then adding tert-butyl alcohol in an amount of 0.1-0.15 times the mass of the polymerization monomers, stirring uniformly, then adding ammonium persulfate in an amount of 0.06-0.08 times the mass of the polymerization monomers dropwise, reacting at a temperature of 85-95℃ for 3-4h, after the reaction is completed, rotary evaporation at a temperature of 70-80℃ and a pressure of 266Pa for 2-2.5h, and then preparing an oily copolymer;

[0012] S2, placing the cleaned and dried porous ceramic particles in a negative pressure vacuum environment for 0.5-1h, then adding the oily copolymer in an amount of 2-3 times the mass of the porous ceramic particles, vacuumizing again, and heating to 70-80℃, continuously adsorbing for 2-3h, then turning off the vacuum, filtering and air-drying the filtered product, spraying a saturated solution of aluminum dihydrogen tripolyphosphate on the air-dried product, air-drying again after spraying once, and repeating the spraying 2-3 times, and then preparing the silicon removal agent.

[0013] As an optimization, the acidified modified monomer comprises the following preparation steps: adding the modified monomer to hydrochloric acid in an amount of 6-8 times the mass of the modified monomer, stirring and reacting at a temperature of 25-35℃ for 24-26h, after the reaction is completed, adjusting the pH to 5 with a 5% sodium hydroxide solution, removing the excess solvent by rotary evaporation, and then filtering to prepare the acidified modified monomer.

[0014] As an optimization, the modified monomer comprises the following preparation steps: adding maleic anhydride to deionized water in an amount of 10-12 times the mass of the maleic anhydride, stirring and dissolving, then adding diethyl iminodiacetate in an amount of 1.8-2 times the mass of the maleic anhydride dropwise, adjusting the temperature to 55-65℃ after the dropwise addition is completed, reacting for 3-4h, vacuum drying for 2-3h after the reaction is completed, crushing the vacuum dried product, washing with acetone for 3-5 times, and then constant temperature drying for 24-26h to prepare the modified monomer.

[0015] As optimization, the physicochemical system specifically comprises: the material preliminarily adjusted by the adjusted pool is pumped into the efficient air flotation system by a lifting pump, an appropriate amount of flocculant and coagulant aid are sequentially added, and compressed air is punched into the dissolved air tank to form a gas-water mixture, after the gas-water mixture is released by a dissolved air releaser, the upper layer sludge is removed by a chain type slag scraper, and the lower layer clear water enters the biochemical system.

[0016] As optimization, the biochemical system specifically comprises: the clear water of the physicochemical system enters the softening and precipitation system, a coagulant, a flocculant, sodium carbonate and sodium hydroxide are added into the softening and precipitation pool, mud-water separation is carried out through the softening and precipitation pool, the supernatant enters the catalytic oxidation pool, polyaluminum chloride, polyacrylamide, a desiliconizing agent and dilute hydrochloric acid are added into the catalytic oxidation pool, the supernatant of the catalytic oxidation pool enters the intermediate water pool, passes through a multi-medium filter, the filtered water enters the ultrafiltration system.

[0017] As optimization, the ultrafiltration system specifically comprises: the filtered water of the multi-medium filter enters the UF system and is input into a UF water tank, and the water outlet of the UF water tank enters the DTRO system.

[0018] As optimization, the DTRO system specifically comprises: the water outlet of the UF water tank enters the DTRO membrane system device, the water outlet of the DTRO membrane system device enters the secondary RO system, and the water outlet is guided into a recycled water pool, and the recycled water is up to standard; wherein the concentrated water generated by the secondary RO system is returned to the UF water tank, and the concentrated water generated by the DTRO membrane system device enters the energy-saving evaporation system through the softening and precipitation pool and the multi-medium filter.

[0019] As optimization, the energy-saving evaporation system specifically comprises: the concentrated water generated by the DTRO membrane system device enters the evaporation raw water pool through the softening and precipitation pool and the multi-medium filter, and then part of the water is discharged up to standard, and the part of the water that is not up to standard is sent to the secondary RO system.

[0020] Compared with the prior art, the present application has the following beneficial effects:

[0021] The preparation of the modified monomer adopts nucleophilic acyl substitution reaction of maleic anhydride and imino diethyl acetate, and this reaction path lays a key foundation for silicon activity. In the nucleophilic acyl substitution, the carbonyl carbon of maleic anhydride is attacked by the nitrogen atom of imino, the anhydride ring is opened to form an amide bond and a carboxyl precursor, and it is easier to introduce dense acidifiable functional groups in the molecule. The subsequent hydrochloric acid acidification treatment can convert these functional groups into a large number of carboxyl groups, not only enhancing the chelation ability to the metal cations accompanying in the silicon scale, but also inhibiting the polymerization of silicon-oxygen bond in the acidic environment, further ensuring the carboxyl density in the copolymer, and providing sufficient active sites for efficient silicon removal.

[0022] The synergistic effect of the functional groups in the ternary copolymer system achieves all-round coverage of the desilication performance. The hydroxyl group of hydroxyethyl methacrylate can be combined with the silicon hydroxyl group on the surface of the silica scale through hydrogen bonding, thereby strengthening the adsorption of the copolymer on the silica scale; the sulfonic acid group of 2-acrylamido-2-methylpropanesulfonic acid sodium salt has strong polarity and salt resistance, thereby avoiding the salting-out of the copolymer in a high-salt water body and dispersing the silicon microcrystals through electrostatic repulsion; and the carboxyl group of the acid-modified monomer can chelate metal ions and destroy the silica scale lattice, and the adsorption of the hydroxyl group and the dispersion of the sulfonic acid group form a closed loop of adsorption-chelation-dispersion, thereby significantly improving the removal efficiency of the silica scale;

[0023] The selection of the free radical polymerization method provides process guarantee for the performance of the copolymer. The method has mild reaction conditions and causes little damage to the active functional groups such as the carboxyl group and the amide group in the modified monomer obtained through nucleophilic acyl substitution, thereby completely retaining the desilication activity of the functional groups. Meanwhile, by adjusting the amount of the initiator and the reaction time, the oil-like copolymer can be stably prepared, which not only avoids the problem of the closure of the active sites of high-molecular-weight polymers but also facilitates the subsequent uniform adsorption of the copolymer in the pores of the porous ceramic particles, thereby ensuring that the functional groups are fully exposed to the water body.

[0024] The adsorption of the porous ceramic particles solves the problem of the easy loss of the free copolymer and significantly improves the actual application efficiency. The high specific surface area and the porous structure of the ceramic material can uniformly fix the oil-like copolymer in the pores, thereby greatly increasing the contact area between the copolymer and the silica scale in the water body. Meanwhile, the physical adsorption of the ceramic can "anchor" the copolymer, thereby reducing the loss of the desilication agent caused by water flow scouring, allowing the water body to slowly penetrate through the pores and fully react with the copolymer, thereby reducing the dosage and prolonging the single-use period. In addition, the acid- and alkali-resistant and corrosion-resistant properties of the ceramic ensure the stability of the structure in a complex water treatment environment, thereby providing long-term protection for the copolymer.

[0025] The surface-sprayed aluminum dihydrogen tripolyphosphate encapsulation layer provides double insurance for the long-term effectiveness and stability of the desilication agent. The extremely low water solubility of aluminum dihydrogen tripolyphosphate allows it to form a dense and slowly dissolving film, so that the copolymer is not released instantaneously but slowly leaches out as the encapsulation layer dissolves, thereby effectively prolonging the action time. Meanwhile, the encapsulation layer can isolate the direct contact between the suspended particles and microorganisms in the water body and the copolymer, thereby preventing the copolymer from being contaminated or biodegraded and protecting the stability of the chemical structure of the copolymer. More importantly, the inorganic phosphate characteristics of aluminum dihydrogen tripolyphosphate can cooperate with the carboxyl group and the sulfonic acid group of the copolymer to further chelate metal ions, thereby enhancing the inhibition effect on the silica scale and the composite scale. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The process flowchart of the present application is shown in the figure. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0028] Embodiment 1

[0029] S1, maleic anhydride is added to deionized water 10 times the mass of maleic anhydride, after stirring and dissolving, then 1.8 times the mass of maleic anhydride diethyl imino diacetate is added dropwise, after the dropwise addition is completed, the temperature is adjusted to 55℃ and reacted for 3h, after the reaction is completed, vacuum drying for 2h, and the vacuum dried product is crushed and washed with acetone solution for 3 times, then constant temperature drying for 24h, to obtain a modified monomer

[0030] S2, the modified monomer is added to hydrochloric acid 6 times the mass of the modified monomer, stirred at a temperature of 25℃ for 24h, after the reaction is completed, a 5% sodium hydroxide solution is added to adjust the pH to 5, after rotary evaporation to remove excess solvent, filtration is performed, to obtain an acidified modified monomer

[0031] S3, according to the mass ratio of 1:1:2.4, hydroxyethyl methacrylate, 2-acrylamido-2-methyl propane sulfonic acid sodium and acidified modified monomer are weighed as polymerization monomers, added to deionized water 2 times the mass of the polymerization monomers, stirred uniformly, then 0.1 times the mass of the polymerization monomers of tert-butyl alcohol is added, after stirring uniformly, 0.06 times the mass of the polymerization monomers of ammonium persulfate is added dropwise, reacted at a temperature of 85℃ for 3h, after the reaction is completed, rotary evaporation is performed at a temperature of 70℃ and 266Pa for 2h, to obtain an oily copolymer;

[0032] S4, after the porous ceramic particles are washed and dried, they are placed in a negative pressure vacuum environment for 0.5h, then 2 times the mass of the oily copolymer is added to the porous ceramic particles, vacuum is drawn, and the temperature is raised to 70℃, and the adsorption is continued for 2h, then the vacuum is closed, and the product is filtered and naturally air dried, after air drying, a saturated aluminum dihydrogen tripolyphosphate solution is sprayed, after spraying once, air drying is performed, and the spraying is repeated twice, to obtain a silicon removal agent.

[0033] Embodiment 2

[0034] S1, maleic anhydride is added to deionized water 11 times the mass of maleic anhydride, after stirring and dissolving, 1.9 times the mass of maleic anhydride diethyl imino diacetate is added dropwise, after the dropwise addition is completed, the temperature is adjusted to 60℃ and reacted for 3.5h, after the reaction is completed, vacuum drying for 2.5h, and the vacuum dried product is crushed and washed with acetone solution for 4 times, then constant temperature drying for 25h, to obtain a modified monomer

[0035] S2, the modified monomer is added to hydrochloric acid 7 times the mass of the modified monomer, stirred at 30℃ for 25h, after the reaction is completed, a 5% sodium hydroxide solution is added to adjust the pH to 5, after the excess solvent is removed by rotary evaporation, filtration is performed, and an acidified modified monomer is prepared

[0036] S3, the hydroxyethyl methacrylate, 2-acrylamido-2-methylpropanesulfonic acid sodium and acidified modified monomer are weighed according to the mass ratio of 1:1:2.6 as polymerization monomers, added to deionized water 3 times the mass of the polymerization monomers, stirred uniformly, then added to tert-butyl alcohol 0.125 times the mass of the polymerization monomers, stirred uniformly, then added to ammonium persulfate 0.07 times the mass of the polymerization monomers, reacted at 90℃ for 3.5h, after the reaction is completed, rotary evaporation is performed at 75℃ and 266Pa for 2.5h, and an oil-like copolymer is prepared;

[0037] S4, the porous ceramic particles after cleaning and drying are placed in a negative pressure vacuum environment for 0.75h, then the oil-like copolymer 2.5 times the mass of the porous ceramic particles is added, vacuum is applied, and the temperature is raised to 75℃, and the adsorption is continued for 2.5h, then the vacuum is turned off, suction filtration is performed, and the suction filtration product is naturally air-dried, after air-drying, a tridibasic aluminum phosphate saturated solution is sprayed, after spraying once, air-drying is performed, and the spraying is repeated 2.5 times, and a silicon removal agent is prepared.

[0038] Example 3:

[0039] S1, maleic anhydride is added to deionized water 12 times the mass of the maleic anhydride, stirred and dissolved, then diethyl iminodiacetate 2 times the mass of the maleic anhydride is added dropwise, the temperature is adjusted to 65℃ after the dropwise addition is completed, and the reaction is performed for 4h, after the reaction is completed, vacuum drying is performed for 3h, the vacuum dried product is crushed and washed with acetone solution 5 times, then constant temperature drying is performed for 26h, and a modified monomer is prepared

[0040] S2, the modified monomer is added to hydrochloric acid 8 times the mass of the modified monomer, stirred at 35℃ for 26h, after the reaction is completed, a 5% sodium hydroxide solution is added to adjust the pH to 5, after the excess solvent is removed by rotary evaporation, filtration is performed, and an acidified modified monomer is prepared

[0041] S3, the hydroxyethyl methacrylate, 2-acrylamido-2-methylpropanesulfonic acid sodium and acidified modified monomer are weighed according to the mass ratio of 1:1:2.8 as polymerization monomers, added to deionized water 4 times the mass of the polymerization monomers, stirred uniformly, then added to tert-butyl alcohol 0.15 times the mass of the polymerization monomers, stirred uniformly, then added to ammonium persulfate 0.08 times the mass of the polymerization monomers, reacted at 95℃ for 4h, after the reaction is completed, rotary evaporation is performed at 80℃ and 266Pa for 2.5h, and an oil-like copolymer is prepared;

[0042] S4, the porous ceramic particles after cleaning and drying were placed in a negative pressure vacuum environment for 1 h, then oil copolymer with 3 times the mass of the porous ceramic particles was added, vacuum was drawn again, and the temperature was raised to 80℃, and adsorption was continued for 3 h, then the vacuum was closed, and the product was filtered and naturally air-dried, then the air-dried product was sprayed with a saturated solution of aluminum dihydrogen tripolyphosphate, and the spraying was repeated 3 times, and the silicon removal agent was prepared.

[0043] Example 4:

[0044] The difference from Example 2 is only in step S3: hydroxyethyl methacrylate, sodium 2-acrylamido-2-methylpropanesulfonate and modified monomer were weighed according to a mass ratio of 1:1:2.6 as polymerization monomers, added to deionized water with 3 times the mass of the polymerization monomers, stirred uniformly, then tert-butyl alcohol with 0.125 times the mass of the polymerization monomers was added, after stirring uniformly, ammonium persulfate with 0.07 times the mass of the polymerization monomers was added dropwise, the reaction was carried out at a temperature of 90℃ for 3.5 h, after the reaction, rotary evaporation was carried out at a temperature of 75℃ and 266 Pa for 2.5 h, and the oil copolymer was prepared;

[0045] Example 5:

[0046] The difference from Example 2 is only in step S3: hydroxyethyl methacrylate, sodium 2-acrylamido-2-methylpropanesulfonate and maleic anhydride were weighed according to a mass ratio of 1:1:2.6 as polymerization monomers, added to deionized water with 3 times the mass of the polymerization monomers, stirred uniformly, then tert-butyl alcohol with 0.125 times the mass of the polymerization monomers was added, after stirring uniformly, ammonium persulfate with 0.07 times the mass of the polymerization monomers was added dropwise, the reaction was carried out at a temperature of 90℃ for 3.5 h, after the reaction, rotary evaporation was carried out at a temperature of 75℃ and 266 Pa for 2.5 h, and the oil copolymer was prepared;

[0047] Example 6:

[0048] The difference from Example 2 is only in step S3: hydroxyethyl methacrylate and sodium 2-acrylamido-2-methylpropanesulfonate were weighed according to a mass ratio of 1:1 as polymerization monomers, added to deionized water with 3 times the mass of the polymerization monomers, stirred uniformly, then tert-butyl alcohol with 0.125 times the mass of the polymerization monomers was added, after stirring uniformly, ammonium persulfate with 0.07 times the mass of the polymerization monomers was added dropwise, the reaction was carried out at a temperature of 90℃ for 3.5 h, after the reaction, rotary evaporation was carried out at a temperature of 75℃ and 266 Pa for 2.5 h, and the oil copolymer was prepared;

[0049] The materials prepared in the above Examples 1-6 were tested for the following properties, and the test methods are as follows, and the test results are shown in Table 1 below:

[0050] 5g of the prepared silicon removal agent was added to 500mL of deionized water, and a static release test was carried out at 70°C. Every 5 days, 100mL of solution was taken out and 100mL of deionized water was added. The removed solution was added to 500mL of water sample treated by the physical and chemical system. The silicon content was determined according to GB / T 12149-2017 "Determination of silicon in industrial circulating cooling water and boiler water";

[0051] Table 1

[0052] ;

[0053] As shown by the data in Table 1, the silicon removal efficiency of the silicon removal agent prepared in Examples 1-3 is good and relatively stable.

[0054] The various indicators of Example 4 also perform well, and the main reason for the performance decline is that the carboxyl group is less due to the lack of acidification treatment. In Example 5, the performance is improved compared to Example 4, mainly because the polymerization of maleic anhydride produces two carboxyl groups, so the performance is improved. Example 6 performs the worst, mainly because the lack of a large number of carboxyl groups results in the worst performance.

[0055] Example 7:

[0056] Referring to the process flow in Figure 1 , the fracturing flowback fluid is collected into a conditioning tank, pumped to an efficient air flotation system by a booster pump, and a proper amount of flocculant and coagulant aid is added in turn. The suspended solids in the wastewater gradually form larger particle size flocs. Compressed air forms a gas-liquid mixture in the dissolved air tank. After the gas-liquid mixture is released by the dissolved air release device, small particle size bubbles are formed in the wastewater, and the flocs and oil combine to form a floating layer on the water surface. The upper layer of flocs and floating oil is removed by a chain-type slag scraper on the upper layer. The lower layer of clear water enters a softening and desilication sedimentation tank, and the upper layer of sludge enters a sludge tank.

[0057] The clear water from the air flotation system enters the softening and desilication sedimentation tank. Coagulant, flocculant, sodium carbonate, and sodium hydroxide are added to the reaction tank to separate the sludge and water in the softening and sedimentation tank, thereby removing suspended solids, silicon, and hardness. The supernatant enters the catalytic oxidation tank, and coagulant, flocculant, desilication agent, and dilute hydrochloric acid are added to the reaction tank to further remove suspended solids, silicon, and hardness. The supernatant from the catalytic oxidation enters the intermediate transition tank. When the water flows into the filter layer, the sand particles in the filter material layer are arranged more tightly, so the water particles have more opportunities to collide with the sand particles. The coagulation flocs, suspended solids, and sand particle surfaces adhere to each other, and the impurities in the water are trapped in the filter material layer, thereby obtaining clear water quality. The sand filter produces water, which enters the UF system. The main function of the UF system is to further filter and remove suspended solids to ensure stable operation of the downstream membrane system.

[0058] The water produced by the UF system enters the UF water tank and then enters the DTRO system, the high pressure resistance and strong anti-pollution ability of the DTRO membrane are utilized to intercept and remove most of the soluble salts and organic matters in the wastewater, the water produced by the DTRO system is concentrated by the membrane system and stored in the DTRO water tank, and then enters the secondary RO system, the RO produced water enters the reuse water tank and is reused, the concentrated water of the DTRO system has high hardness after concentration, so it needs to be softened again, the concentrated water of the DTRO system enters the softening sedimentation tank, and then is filtered by quartz sand and evaporated in the raw water tank, and then a part of it is evaporated by the MVR to enter the DTRO water tank, and another part enters the liquid solidification machine, and a part of it is returned to the DTRO water tank, and another part is discharged.

[0059] The cleaning water of the quartz sand filter and the softening sedimentation tank and the drainage water of the adjusting tank enter the materialized sludge tank for treatment, and then enter the conditioning tank, and finally enter the plate and frame filter press to remove the sludge, and the filtered water is returned to the adjusting tank.

[0060] The sludge produced by the high-efficiency air flotation system, the softening sedimentation system, the catalytic oxidation system and the concentrated water softening sedimentation system is pumped to the sludge tank, and after adding PAM (+) conditioning, it is dewatered and reduced in quantity by the filter press, the filter liquid of the filter press is returned to the adjusting tank, and the dewatered sludge is disposed by others.

[0061] It is apparent to those skilled in the art that the present application is not limited to the details of the foregoing exemplary embodiments, and that the present application can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered in all respects as illustrative and not restrictive, the scope of the present application being defined by the appended claims rather than the foregoing description, and it is intended that all changes that come within the meaning and range of equivalency of the claims are embraced therein. Any reference signs in the claims should not be construed as limiting the claims.

Claims

1. A zero-discharge treatment process for industrial wastewater, characterized in that: The following steps are involved: The fracturing flowback fluid is processed through preliminary conditioning, physical and chemical system, biochemical system, ultrafiltration system, DTRO system, energy-saving evaporation system and liquid solidification machine system to achieve zero discharge and meet the environmental protection requirements for wastewater treatment; A desiliconizer is added to the biochemical system, wherein the desiliconizer is prepared by free radical polymerization of hydroxyethyl methacrylate, sodium 2-acrylamido-2-methylpropanesulfonate, and an acid-modified monomer in a mass ratio of 1:1:2.4-2.8 to obtain an oily copolymer. The oily copolymer is then adsorbed on porous ceramic particles and sprayed and encapsulated on the surface with aluminum dihydrogen tripolyphosphate. The acidified modified monomer is prepared by acidifying the modified monomer with hydrochloric acid, wherein the modified monomer is formed by a nucleophilic acyl substitution reaction of the imino group in diethyl iminodiacetate with maleic anhydride.

2. The zero-discharge treatment process for industrial wastewater according to claim 1, characterized in that: The silicon remover comprises the following preparation steps: S1. The silicon remover comprises the following preparation steps: hydroxyethyl methacrylate, sodium 2-acrylamido-2-methylpropanesulfonate and an acid-modified monomer are weighed as polymerization monomers in a mass ratio of 1:1:2.4-2.8, added to deionized water 2-4 times the mass of the polymerization monomer, stirred evenly, and then tert-butyl alcohol 0.1-0.15 times the mass of the polymerization monomer is added, stirred evenly, and then ammonium persulfate 0.06-0.08 times the mass of the polymerization monomer is added dropwise, and the reaction is carried out at a temperature of 85-95°C for 3-4 hours. After the reaction is completed, the reaction is carried out at a temperature of 70-80°C and 266Pa for 2-2.5 hours to obtain an oily copolymer; S2. Place the cleaned and dried porous ceramic particles in a negative pressure vacuum environment for 0.5 to 1 hour, then add an oily copolymer 2 to 3 times the mass of the porous ceramic particles, evacuate the mixture, and heat to 70 to 80°C. Continue adsorbing for 2 to 3 hours. Then turn off the vacuum, filter, and air-dry the filtered product. After air-drying, spray with a saturated solution of aluminum dihydrogen tripolyphosphate. After spraying once, air-dry and spray again. Repeat 2 to 3 times to obtain a desiliconizer.

3. The zero-discharge treatment process for industrial wastewater according to claim 2, characterized in that: The acid-modified monomer comprises the following preparation steps: adding the modified monomer to hydrochloric acid 6 to 8 times the mass of the modified monomer, stirring and reacting at a temperature of 25 to 35° C. for 24 to 26 hours, adding a 5% by mass sodium hydroxide solution after the reaction to adjust the pH to 5, rotary evaporating to remove excess solvent, and filtering to obtain the acid-modified monomer.

4. The zero-discharge treatment process for industrial wastewater according to claim 2, characterized in that: The modified monomer comprises the following preparation steps: adding maleic anhydride to deionized water with a mass of 10 to 12 times that of the maleic anhydride, stirring and dissolving, then dropwise adding diethyl iminodiacetate with a mass of 1.8 to 2 times that of the maleic anhydride, adjusting the temperature to 55 to 65° C. after the dropwise addition is complete, reacting for 3 to 4 hours, vacuum drying for 2 to 3 hours after the reaction is complete, crushing the vacuum-dried product, washing it with an acetone solution for 3 to 5 times, and then drying it at a constant temperature for 24 to 26 hours to obtain the modified monomer.

5. The zero-discharge treatment process for industrial wastewater according to claim 1, characterized in that: The physicochemical system specifically includes: pumping the material after preliminary adjustment in the regulating tank into the high-efficiency flotation system through a lifting pump, adding appropriate amounts of flocculants and coagulant aids in sequence, and injecting compressed air to form a gas-water mixture in the dissolved air tank. After the gas-water mixture is released through the dissolved air releaser, the upper layer of mud and residue is removed by the upper chain scraper, and the clear water in the lower layer enters the biochemical system.

6. The zero-discharge treatment process for industrial wastewater according to claim 1, characterized in that: The biochemical system specifically includes: the clean water from the physicochemical system enters the softening sedimentation system, coagulant, flocculant, sodium carbonate and sodium hydroxide are added to the softening sedimentation tank, mud and water are separated through the softening sedimentation tank, the supernatant enters the catalytic oxidation tank, polyaluminum chloride, polyacrylamide, silicon remover and dilute hydrochloric acid are added to the catalytic oxidation tank, the supernatant of the catalytic oxidation tank enters the intermediate water tank, passes through the multi-media filter, filters the produced water, and enters the ultrafiltration system.

7. The zero-discharge treatment process for industrial wastewater according to claim 1, characterized in that: The ultrafiltration system specifically includes: a multi-media filter filters the produced water into the UF system, and inputs it into the UF water production tank, and the water out of the UF water production tank enters the DTRO system.

8. The zero-discharge treatment process for industrial wastewater according to claim 1, characterized in that: The DTRO system specifically includes: the effluent from the UF water production tank enters the DTRO membrane system device, the water produced by the DTRO membrane system device enters the secondary RO system and is introduced into the reuse water tank for reuse when it meets the standards; the concentrated water produced by the secondary RO system is returned to the UF water production tank, and the concentrated water produced by the DTRO membrane system device enters the energy-saving evaporation system through the softening sedimentation tank and the multi-media filter.

9. The zero-discharge treatment process for industrial wastewater according to claim 1, characterized in that: The energy-saving evaporation system specifically includes: the concentrated water generated by the DTRO membrane system device passes through the softening sedimentation tank and the multi-media filter into the evaporation raw water tank, and then passes through the MVR evaporation and liquid solidification machine. Part of it meets the discharge standards, and the part that does not meet the standards is sent to the secondary RO system.

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