A precise interception purification method for water treatment

Abstract

The application discloses a precision interception purification method for water treatment, and belongs to the technical field of drinking water purification. The method solves the purification problems of high-turbidity composite suspended particles, low-temperature microorganisms, plant source toxins, inorganic-organic composite colloids and the like of seasonal ice and snow melt water in the western Sichuan plateau and other regions, and is suitable for a low-temperature environment of 2-10 DEG C. The method comprises the following steps: S1, adding a composite modified vermiculite (quaternary ammonium salt modified vermiculite + konjac glucomannan-propylene glycol-Xuelingshi composite freeze-dried powder) to a water source to be treated, stirring and then filtering to obtain supernatant; S2, coating a first coating (quaternary ammonium salt modified vermiculite + calcium-doped fly ash) and a second coating (KH-560 modified diatomite) on a porous ceramic support in sequence to prepare a composite membrane; and S3, passing the permeate into a purification column containing a calcium-doped nano-hydroxyapatite coating alumina layer and a modified mesoporous carbon layer, and then performing ultraviolet irradiation to obtain final effluent. The application realizes precision interception of multiple impurities and improves the safety of plateau drinking water.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of drinking water purification, and particularly relates to a precise interception purification method for water treatment. BACKGROUND

[0002] In the regions of the western Sichuan plateau and the border between Sichuan and Yunnan, the core drinking water source of rural residents and border sentries is a seasonal mixed water source of ice-snow melt water and surface runoff. Although the water source is not polluted by industry and belongs to a natural water source, it is affected by the unique formation path of "ice-snow melting-surface runoff", and is rich in various special impurities. The existing water treatment technology is difficult to adapt, which seriously restricts the safety guarantee of drinking water in the region.

[0003] Firstly, there is the problem of suspended particles. During the concentrated ice-snow melting period from April to June every year, the melt water will wash the weathered rock debris and meadow humus exposed on the surface of the earth, forming high-turbidity pulse pollution - the turbidity can suddenly increase from 5 NTU in the dry season to more than 500 NTU. The fine particle sediment with a particle size of 0.1-10 microns accounts for more than 60%, and will wrap a large amount of flocculent humus to form particle-organic compound suspended matter. Unlike the single and low fluctuation suspended particles in conventional water sources, this kind of fine particles have strong dispersibility and great turbidity fluctuation amplitude; in addition, the water source is in a low-temperature environment of 4-10℃ all year round, and the flocculation efficiency of conventional coagulants is greatly reduced, so the traditional sedimentation process cannot realize effective sedimentation separation, and the filter material is also easy to be penetrated and clogged.

[0004] Secondly, there is the symbiotic pollution of low-temperature microorganisms and metabolites. When the melt water passes through the plateau meadow, it will enrich cold-resistant microorganisms such as pseudomonas and low-temperature bacillus, and at the same time, it will carry plant-derived toxins such as pyrrolizidine alkaloids. The low-temperature environment not only inhibits the activity of conventional disinfectants such as chlorine preparations, but also makes the microorganisms easily adhere to the surface of suspended particles to form a bacterial biofilm protection layer, resulting in incomplete disinfection; and the molecular weight of this kind of plant-derived toxins is mostly 300-500 Da, which is difficult to be effectively intercepted by conventional adsorption technology.

[0005] Thirdly, there is the problem of mineral colloids. The calcium and magnesium ions and silicates contained in the water source can easily form metastable colloids with a particle size of 20-100 nm in a low-temperature environment of 4-10℃; the colloids can also combine with humus through hydrogen bonds to form more stable inorganic-organic composite colloids. The interception effect of conventional ultrafiltration membranes on this kind of composite colloids is limited, and the colloids can easily form a dense pollution layer on the membrane surface, leading to rapid decay of membrane flux and further reducing the treatment efficiency.

[0006] In addition, the water source also has plateau-specific plant low-temperature stable secondary metabolites. When the melting water passes through the growth area of plateau-specific toxic plants such as Stellera chamaejasme and Yunnan patrinia, wolftail and aconitine substances will be dissolved. Such substances are stable in chemical properties at low temperatures of 4-10 DEG C and are difficult to be naturally degraded, and the molecular mass is only 150-300 Da, and the conventional ultrafiltration membrane and activated carbon cannot effectively intercept and adsorb.

[0007] Therefore, how to provide a method for solving the impurities in the mixed water source of ice-snow melt water and surface runoff is extremely important. SUMMARY

[0008] The purpose of the present application is to provide a precise interception purification method for water treatment, which effectively solves the impurity and potential heavy metal pollution problems of the mixed water source of seasonal ice-snow melt water and surface runoff in the western Sichuan plateau and the Sichuan-Yunnan border area.

[0009] The purpose of the present application is achieved by the following technical solutions:

[0010] A precise interception purification method for water treatment, comprising the following steps:

[0011] S1. Low-temperature adaptation pretreatment:

[0012] A composite modified vermiculite is added to the water source to be treated at 2-10 DEG C, and after sufficient stirring, the supernatant is obtained by filtering through a 40-60 mesh stainless steel filter screen;

[0013] The composite modified vermiculite is prepared by modifying industrial-grade vermiculite with quaternary ammonium salt and then mixing with konjac glucomannan-propylene glycol-snow lingzhi composite freeze-dried powder;

[0014] S2. Composite membrane synergistic treatment:

[0015] S21. Composite membrane preparation: The first coating and the second coating are successively immersed on the porous ceramic support;

[0016] The first coating comprises quaternary ammonium salt modified vermiculite and calcium doped fly ash;

[0017] The second coating comprises KH-560 modified diatomite, rhodiola rosea polysaccharide, mercaptopropyl sulfonic acid and calcium doped nano-hydroxyapatite;

[0018] S22. Interception operation: The supernatant obtained in step S1 is pumped into the composite membrane system, and after operation, the reverse flushing is performed with a flushing liquid containing disodium EDTA and citric acid;

[0019] S3. Deep purification treatment:

[0020] S31. The permeate of step S22 is introduced into the purification column, and the calcium doped nano-hydroxyapatite coating alumina layer and the modified mesoporous carbon layer are sequentially arranged in the column from bottom to top;

[0021] The modified mesoporous carbon is prepared by mixing and carbonizing the three of highland barley straw, waste edible mushroom dregs and CaO, then activating by KOH, mixing with a complex solution of snow lingzhi-propylene glycol-konjac glucomannan-sodium alginate-snowy sea-buckthorn pomace, and finally soaking in a quaternary ammonium salt solution;

[0022] S32. The purified column permeate is irradiated with ultraviolet light to obtain the final effluent.

[0023] In some embodiments of the present application, in step S1, the composite modified vermiculite is prepared by mixing vermiculite with a 0.15-0.25 mol / L quaternary ammonium salt solution at a mass ratio of 1:(18-22).

[0024] The konjac glucomannan-propylene glycol-snow lingzhi composite freeze-dried powder is prepared by mixing konjac glucomannan, food-grade propylene glycol and snow lingzhi water extract at a mass ratio of (0.8-1.5):(0.15-0.25):3, and then vacuum freeze-drying at -45~- 35℃ and crushing.

[0025] In some embodiments of the present application, in step S1, an intelligent ultrasonic generator is provided to achieve sufficient stirring, the power adjustment range of the intelligent ultrasonic generator is 150-210W, the ultrasonic frequency adjustment range is 25-33kHz, and the generator is built-in with a double-input-three-output parameter adaptive chip, which controls the stirring speed through a pre-set altitude-water temperature-rotation speed mapping algorithm: the chip collects the detection data of the altitude sensor and the water temperature sensor in real time (2 input parameters), compares with the built-in parameter table to output control signals, and automatically adjusts the ultrasonic power, ultrasonic frequency and stirring speed (3 output operating parameters) to the corresponding interval.

[0026] The specific adaptation logic is as follows:

[0027] When the altitude of the processing scene is in the interval of 2800-3500m: if the water temperature of the water to be processed is 2-4℃, the ultrasonic generator automatically adjusts the power to 180-200W and the frequency to 29-32kHz, while cooperating with a stirring speed of 100-120r / min, and after stirring, it is placed for 11-13min; if the water temperature of the water to be processed is 5-10℃, the ultrasonic generator automatically adjusts the power to 160-180W and the frequency to 27-30kHz, while cooperating with a stirring speed of 90-110r / min, and after stirring, it is placed for 10-12min.

[0028] When the altitude of the processing scene is in the interval of 3501-4500m: if the water temperature of the water source to be processed is 2-4℃, the ultrasonic generator automatically adjusts the power to 190-210W and the frequency to 31-33kHz, while cooperating with the stirring speed of 110-130r / min, and after stirring, it is placed for 12-14min; if the water temperature of the water source to be processed is 5-10℃, the ultrasonic generator automatically adjusts the power to 170-190W and the frequency to 29-31kHz, while cooperating with the stirring speed of 100-120r / min, and after stirring, it is placed for 11-13min.

[0029] In actual implementation, in the actual scene of the Sichuan West Plateau and the Sichuan-Yunnan border area with large altitude span (2800-4500m), water temperature fluctuation (2-10℃) and low temperature environment, the flocculation efficiency is easily affected. The low air pressure and oxygen content in the high altitude area will cause insufficient energy transmission of the conventional fixed power ultrasonic stirring, and the low altitude area may cause the flocculation to be broken due to excessive energy. The water temperature fluctuation will also affect the molecular activity of konjac glucomannan and snow lingzhi polysaccharide. In this scheme, by introducing a double-input-three-output parameter adaptive chip, real-time data can be collected through the chip, and the ultrasonic power, frequency and stirring speed can be automatically adjusted according to the preset logic to compensate for the adverse effects of the environment on flocculation, while matching the corresponding standing time, which not only ensures the stable aggregation of the flocculation in different scenes, but also reduces the cost of manual intervention, optimizes the processing efficiency, and adapts to the actual operation and maintenance of the plateau.

[0030] As some implementable manners of the present application, in step S21, the specific preparation method of the porous ceramic support is as follows:

[0031] (1) After the yak bones discarded in the plateau pastoral area are ground to a particle size of 4-12μm, they are calcined at 780-820℃ for 1.8-2.2h, cooled, and then sieved through a 180-220 mesh screen to obtain calcined yak bone powder;

[0032] (2) The earthenware clay, calcined yak bone powder and deionized water are mixed in a mass ratio of 9:(0.5-1.5):(2.8-3.2), kneaded into a uniform body, extruded into a columnar shape, and then fired to obtain the finished product; the finished product has a porous structure.

[0033] In this scheme, the support is prepared by using the discarded yak bones in the plateau and the local earthenware clay, reducing the transportation cost of purchased raw materials, realizing the resource utilization of discarded slaughter waste, solving the environmental protection problem, and the support is prepared by mixing the calcined yak bone powder and the earthenware clay.

[0034] As some implementable manners of the present application, the length of the ceramic support is 150-200mm, and the diameter is 30-40mm; the porous aperture is 3-15μm, and the porosity is 35-45%.

[0035] As some embodiments of the present application, in step S21, the second coating is made by mixing KH-560 modified diatomite, a red ginseng polysaccharide solution with a mass concentration of 3-7%, calcium-doped nano-hydroxyapatite, and mercaptopropyl sulfonic acid at a mass ratio of 4:(0.8-1.2):(0.2-0.45):(0.004-0.006).

[0036] As some embodiments of the present application, in step S31, the inner diameter of the purification column is 80-100 mm; and the height ratio of the calcium-doped nano-hydroxyapatite coating layer to the modified mesoporous carbon layer is 1:(7-12).

[0037] Compared with the prior art, the present application has the following advantages:

[0038] The present application provides a precision interception purification method for water treatment, which effectively solves the problems of four impurities, i.e., high-turbidity composite suspended particles, low-temperature microorganisms and plant-derived toxins, inorganic-organic composite colloids, and small-molecule plant secondary metabolites, and potential heavy metal pollution in the mixed water source of seasonal ice-snow melt-water and surface runoff in the Sichuan West Plateau and the Sichuan-Yunnan border area, while adapting to the constraints of a low-temperature environment of 2-10℃, as follows:

[0039] Step S1 functions to realize the flocculation separation of composite suspended matter formed by fine particles and humus in the water source through composite modified vermiculite in a low-temperature environment of 2-10℃, thereby greatly reducing the treatment load of subsequent links, as follows:

[0040] In the composite modified vermiculite, quaternary ammonium salt modification can enhance the positive charge density on the surface of vermiculite, adsorb negatively charged humus molecules in water, break the stable dispersion state of humus and fine particles in the composite suspended matter, and solve the problem of weak adsorption capacity of traditional coagulants on this type of suspended matter; the high molecular chains of konjac glucomannan can still maintain good ductility at low temperatures, can entangle fine particles to form stable flocculation skeletons, and avoid the defects of flocculation breakage and low sedimentation efficiency caused by low-temperature environment; the polysaccharide component in the water extract of snow-like ganoderma lucidum can further improve the flocculation density and significantly improve the flocculation settling speed, ensuring the rapid agglomeration of fine particles.

[0041] After sufficient stirring, the agglomerated flocculation is effectively intercepted by filtering through a stainless steel filter screen, laying a good foundation for subsequent composite membrane treatment.

[0042] In addition, the Xuelingshi composite freeze-dried powder has two defects when used alone: one is easy to absorb moisture and form clumps (the large diurnal temperature difference in the plateau and the fluctuation of air humidity easily lead to the agglomeration of the freeze-dried powder, which cannot be uniformly dispersed in water); the other is that the flocculation skeleton is weak (the flocculation formed by the freeze-dried powder alone is difficult to bear the weight of fine particles, and is easily broken during sedimentation). Therefore, food-grade propylene glycol and konjac glucomannan are compounded in the freeze-dried powder in the present application: propylene glycol can form a protective film on the surface of the freeze-dried powder particles, block water adsorption, prevent clumping, and ensure rapid dispersion in water; the long-chain structure of konjac glucomannan can make up for the defect of the weak flocculation skeleton of the freeze-dried powder alone, and further strengthen the flocculation effect.

[0043] The role of step S2: through the composite membrane system, the inorganic-organic composite colloid in water is intercepted, the plant source toxins and part of the heavy metals are removed, and at the same time, the long-term stable operation of the membrane module is maintained through reverse flushing, which is as follows:

[0044] In the porous ceramic support, the porous ceramic support is made of yak bone powder discarded in the plateau pastoral area and pottery clay. The micron-sized pores formed by calcining the yak bone powder can guide the axial penetration of water flow, ensure the full contact of water flow with the subsequent coating, and improve the interception efficiency; at the same time, the waste yak bone is used to realize resource recycling, reduce the cost of raw materials, and adapt to the resource utilization demand of the plateau.

[0045] In the first coating, the quaternary ammonium salt groups on the surface of the quaternary ammonium salt modified vermiculite can further adsorb part of the humus not separated, further reducing the treatment load of the subsequent second coating; the porous structure of calcium-doped fly ash can preliminarily adsorb the inorganic-organic composite colloid in water, avoiding the pollution caused by the direct contact of the colloid with the second coating, and prolonging the effective service life of the second coating.

[0046] In the second coating, the mesoporous structure of KH-560 modified diatomite can screen the inorganic-organic composite colloid, solving the problem of low interception rate of conventional ultrafiltration membranes for such colloids; the red sage polysaccharide can not only enhance the adhesion between the coating and the porous ceramic support, avoiding the coating from falling off due to water flow impact, but also form hydrogen bonds with the hydroxyl groups on the surface of the colloid, further improving the colloid interception effect; the hydroxyl groups of calcium-doped nano-hydroxyapatite can form hydrogen bonds with the amino and carboxyl groups in the plant source toxin molecules, realizing the efficient interception of the plant source toxin, and at the same time, the calcium-doped sites can adsorb lead, cadmium and other heavy metal ions in water through ion exchange, making up for the defect of the insufficient interception of conventional membrane technology for heavy metals; the mercaptopropyl sulfonic acid can combine with the calcium ions on the surface of the calcium-doped nano-hydroxyapatite through the mercapto group, forming steric hindrance, inhibiting the agglomeration of the calcium-doped nano-hydroxyapatite, and ensuring the full exposure of the toxin adsorption sites and the heavy metal ion exchange sites, avoiding the decrease of interception efficiency caused by agglomeration.

[0047] In the backwash, the composite membrane system is backwashed with a backwash solution containing disodium EDTA and citric acid, which can effectively remove the pollutants on the pore of the support and the surface of the coating.

[0048] In addition, the calcium scale covering problem is prone to occur in long-term operation of mercaptopropanesulfonic acid. The calcium ions in the water source (derived from inorganic-organic composite colloids) gradually combine with the mercapto group to form calcium scale, covering the mercapto sites, resulting in a decrease in the ability of the mercapto group to inhibit the agglomeration of calcium-doped nano-hydroxyapatite. At the same time, the calcium scale blocks the porous channels of the support, resulting in a decrease in the membrane flux. The disodium EDTA in the backwash solution can chelate the calcium ions in the calcium scale to form a stable chelate, dissolve the calcium scale, release the covered mercapto sites, and restore the function of inhibiting agglomeration. The citric acid can further dissolve the residual calcium salt and humus, and unblock the porous channels. Through the synergistic action of the two, the membrane flux recovery rate is effectively improved, and the service life of the composite membrane is prolonged.

[0049] The role of step S3 is to intercept small molecule plant secondary metabolites in water, inactivate cold-resistant microorganisms such as Pseudomonas and Bacillus psychrosaccharolyticus, and further remove residual heavy metals, as follows:

[0050] In the purification column, the calcium-doped nano-hydroxyapatite coating alumina can further adsorb the residual colloids and plant-derived toxins in the S2 permeate. The coating structure can prevent the agglomeration of alumina particles, improve the adsorption efficiency, and further intercept the residual heavy metals in water through ion exchange. In the modified mesoporous carbon, the mesoporous structure formed after carbonization and activation can meet the interception requirements of small molecule metabolites. The snow lingzhi polysaccharide and konjac glucomannan can enhance the adsorption capacity of mesoporous carbon. The sodium alginate improves the formability, and the organic acids in the sea-buckthorn pomace can adjust the surface charge of the mesoporous carbon. The quaternary ammonium salt modification further enhances the adsorption of polar small molecule toxins, and the positive charge on the surface can also adsorb heavy metal complexes with negative charge, further strengthening the heavy metal removal effect.

[0051] Ultraviolet irradiation can release ultraviolet light, which can penetrate the microbial biofilm layer and damage the DNA structure of the microorganisms, thereby achieving efficient inactivation of cold-resistant microorganisms.

[0052] In summary, the present application realizes effective treatment of impurities in plateau snowmelt water through the synergistic linkage of the three-stage process, and provides a reliable and sustainable technical solution for the safety of drinking water for rural residents and border posts in the western Sichuan Plateau and the Sichuan-Yunnan border area. DETAILED DESCRIPTION

[0053] Example 1

[0054] S1. Low-temperature adaptation pretreatment.

[0055] Take 100L of water source to be treated, add 0.3% of the compound modified vermiculite according to the mass of the water source, start the conventional stirring device (speed 100r / min) and stir for 20min, then filter through a 50 mesh stainless steel screen, and take the supernatant for standby use.

[0056] The preparation method of the compound modified vermiculite is as follows:

[0057] ① Take 10kg of industrial grade vermiculite and mix with 200kg of 0.2mol / L cetyltrimethylammonium chloride solution, stir and react at 30℃ for 4h, then filter after standing and precipitating, dry the filter cake at 60℃ until constant weight, and crush to a particle size of 50μm to obtain quaternary ammonium salt modified vermiculite;

[0058] ② Take 1.2kg of konjac glucomannan, 0.2kg of food grade propylene glycol and 3kg of snow fungus water extract (take clean and dry snow fungus whole grass (the snow fungus is cushion-shaped snow fungus, purchased from a legal Chinese medicinal material planting base in the western Sichuan plateau), add deionized water at a solid-liquid mass ratio of 1:15, boil and then extract at a slight boil for 2h, filter while hot; add deionized water to the filter residue at a solid-liquid mass ratio of 1:10, extract at a slight boil for 1.5h, and filter twice; combine the two filtrates, concentrate at 60℃ under reduced pressure to 1 / 5 of the original volume, and obtain the snow fungus water extract) according to a mass ratio of 1.2:0.2:3, mix uniformly, and then freeze-dry in a -40℃ vacuum freeze dryer for 12h, crush to a particle size of 80μm after taking out, and obtain a compound freeze-dried powder;

[0059] ③ Mix the quaternary ammonium salt modified vermiculite and the compound freeze-dried powder according to a mass ratio of 5:1, stir for 30min until uniform, and obtain the compound modified vermiculite.

[0060] S2. Compound membrane synergistic treatment.

[0061] S21. Compound membrane preparation:

[0062] ① Porous ceramic support preparation: take 10kg of slaughtered yak bones in the plateau pastoral area, crush to a particle size of 8μm after removing the meat, calcine in a muffle furnace at 780-820℃ for 2h, cool, and pass through a 200 mesh sieve to obtain calcined yak bone powder; take 9kg of pottery clay, 1kg of calcined yak bone powder and 3kg of deionized water according to a mass ratio of 9:1:3, mix and knead into a uniform body, extrude into a solid columnar body with a diameter of 35mm and a length of 180mm, place in a kiln at 1080-1120℃ for 2.2h (heating rate 5℃ / min, cooling rate 3℃ / min), and obtain a porous ceramic support (porous pore size 8μm, porosity 40%);

[0063] ② First coating dipping: take 5 kg of quaternary ammonium salt modified vermiculite (prepared in the same way as in S1 ①) and 5 kg of calcium-doped fly ash according to a mass ratio of 1:1, add 20 kg of deionized water, stir until paste, completely immerse the porous ceramic support in the coating, dip for 30 min under a pressure of 0.02 MPa, and then dry at 80℃ for 2.5 h after taking out;

[0064] ③ Second coating dipping: take 4 kg of KH-560 modified diatomite (take industrial diatomite with a particle size of 5-10 μm, dry at 105℃ for 2 h; take 3% of KH-560 silane coupling agent according to the mass of diatomite, dissolve in anhydrous ethanol (volume ratio of coupling agent to ethanol is 1:10), stir uniformly to prepare a modified solution; add the dried diatomite into the modified solution (solid-liquid mass ratio is 1:8), stir at 50℃ for 3 h, and then filter after standing; dry the filter cake at 80℃ until constant weight, crush to a particle size of 8-12 μm, and obtain KH-560 modified diatomite), 1 kg of 5% red ginseng polysaccharide solution, 0.3 kg of calcium-doped nano-hydroxyapatite, and 0.005 kg of mercaptopropyl sulfonic acid according to a mass ratio of 4:1:0.3:0.005, mix and stir until uniform paste, completely immerse the support treated by the first coating into the second coating, dip for 40 min under an axial pressure of 0.03 MPa, and then dry at 100℃ for 3 h after taking out, to obtain a composite membrane.

[0065] S22. Retention operation:

[0066] Pump the supernatant of S1 into the composite membrane system at a pump pressure of 0.15 MPa, set a ring-shaped water distributor (inner diameter matches the cavity of the composite membrane system) at the water inlet end, evenly open 10 branch pipe interfaces on the water distributor, and connect each interface with one end of the support through a silica gel tube; after the supernatant of S1 is pumped into the ring-shaped water distributor through the main pipeline, it is evenly distributed to each support through the branch pipes. Set a ring-shaped water collector corresponding to the water inlet end at the water outlet end of the composite membrane system, connect the other end of each support with the water collector branch pipe interface through a silica gel tube, and after the permeate of each support flows into the water collector, it enters S3 purification column from bottom to top through the main pipeline at a flow rate of 1.2 L / min. After the composite membrane system is continuously operated for 8 h, reverse flush for 30 min with a flushing liquid containing disodium EDTA and citric acid (disodium EDTA concentration is 0.05 mol / L, citric acid concentration is 0.02 mol / L, and the solvent is deionized water), and the flushing pressure is 0.2 MPa.

[0067] S3. Deep purification treatment.

[0068] S31. Purification column treatment: a stainless steel purification column with an inner diameter of 90 mm and a height of 1.4 m is used, and the column is sequentially filled from bottom to top with calcium-doped nano-hydroxyapatite coated alumina layer and modified mesoporous carbon layer (the lower layer has a height of 110 mm and a filling volume of 0.01 m³, and a 304 stainless steel filter screen with a pore size smaller than the calcium-doped nano-hydroxyapatite coated alumina particle size is arranged at the bottom end to prevent the filler from leaking into the catchment area), the upper layer has a height of 1090 mm, a filling volume of 0.099 m³, and a distance of 0.2 m between the top and the water distribution area; a 304 stainless steel porous compaction plate (pore size 0.5 mm) is arranged above the mesoporous carbon layer, the edge of the compaction plate is sealingly connected with the inner wall of the purification column (food-grade silicone sealing ring is used), to prevent water flow impact from causing the mesoporous carbon to float or loosen.

[0069] The S22 permeate liquid is passed into the purification column at a flow rate of 0.8 L / min, and the residence time is controlled for 30 min.

[0070] The preparation method of the calcium-doped nano-hydroxyapatite coated alumina is as follows:

[0071] (1) Preparation of calcium-doped nano-hydroxyapatite (Ca-HAP): according to a Ca / P molar ratio of 1.7:1, calcium nitrate and diammonium hydrogen phosphate are weighed and dissolved in deionized water (concentration 0.1 mol / L); the diammonium hydrogen phosphate solution is slowly added to the calcium nitrate solution, and ammonia water is used to adjust the pH to 9.0, and the reaction is stirred at 30°C for 3.5 h; after the reaction is completed, the precipitate is collected by filtration after standing for 24 h, and the precipitate is dried at 80°C to constant weight, and then crushed to a particle size of 50-80 nm to obtain Ca-HAP powder.

[0072] (2) Preparation of coated alumina: industrial-grade alumina particles (particle size 2-3 mm, specific surface area 150 m² / g) are dried at 105°C for 2 h.

[0073] A Ca-HAP suspension is prepared according to a mass ratio of Ca-HAP powder: deionized water = 1:10, and 0.5% polyvinyl alcohol by mass of the Ca-HAP suspension is added and stirred until uniform; then, the dried alumina particles (solid-liquid mass ratio 1:5) are added, and the mixture is immersed at 30°C for 2 h, then the excess liquid is drained, and the mixture is dried at 120°C for 1 h; the dried alumina particles are calcined in a muffle furnace at 500°C for 2 h, and then cooled to obtain calcium-doped nano-hydroxyapatite coated alumina.

[0074] The preparation method of the modified mesoporous carbon is as follows: 5 kg of highland barley straw, 3 kg of waste edible mushroom dregs, and 2 kg of CaO are weighed according to a mass ratio of 5:3:2, mixed, and placed in a carbonization furnace for carbonization at 600 DEG C for 3 hours, then 20 kg of KOH solution with a mass concentration of 20% is added after cooling, and the mixture is activated at 800 DEG C for 4 hours, then the mixture is filtered and washed with deionized water until neutral, and then dried and crushed to a particle size of 2 mm; 10 kg of the activated material is weighed according to a mass ratio of 10:1, and 1 kg of a composite solution of snow fungus-propylene glycol-konjac glucomannan-sodium alginate-snowberry pomace (the snowberry pomace is prepared as follows: fresh snowberry fruits are squeezed to obtain juice, and the pomace is collected and dried at 60 DEG C until the water content is less than or equal to 8%, and then crushed to a particle size of 100-120 μm; 5% of deionized water is added to the pomace, stirred for 30 minutes, and then allowed to stand for 1 hour, and then the water-soluble impurities are removed by filtration; the filter residue is dried at 70 DEG C until the weight is constant, and then the snowberry pomace is obtained) is weighed according to a mass ratio of 2:1:3:1:3, mixed, and then soaked in a 0.1 mol / L quaternary ammonium salt solution for 2 hours, and then dried to obtain the modified mesoporous carbon.

[0075] S32. UV irradiation: the S31 permeate is subjected to ultraviolet sterilization (power 8W, sterilization time 2min), the ultraviolet irradiation dose is greater than or equal to 20mJ / cm², the UVC wave band is 254nm, and the final effluent is obtained.

[0076] Example 2

[0077] Compared with Example 1, the following adjustments are made (only the adjustment part is listed, and the rest is the same as Example 1):

[0078] S1. Low-temperature adaptive pretreatment: the composite modified vermiculite dosage is 0.28% of the water source mass;

[0079] In the preparation of the composite freeze-dried powder, the mass ratio of konjac glucomannan, food-grade propylene glycol, and snow fungus water extract is adjusted to 1.0:0.18:3; and when the composite modified vermiculite is mixed, the mass ratio of quaternary ammonium salt modified vermiculite to composite freeze-dried powder is adjusted to 6:1.

[0080] S2. Composite membrane synergistic treatment:

[0081] In the second coating, the rhodiola polysaccharide solution concentration is adjusted to 4%, the amount of calcium-doped nano-hydroxyapatite is adjusted to 0.25 kg, and the amount of mercaptopropyl sulfonic acid is adjusted to 0.0045 kg;

[0082] In S22, the supernatant pump pressure is adjusted to 0.14 MPa, and the permeate flow rate is adjusted to 1.0 L / min.

[0083] S3. Deep purification treatment:

[0084] The permeate flow rate is adjusted to 0.7 L / min, and the residence time is adjusted to 28 min.

[0085] Example 3

[0086] Based on Example 2, the following adjustments are made:

[0087] In step S1, the intelligent ultrasonic generator is introduced for stirring purposes. The details are as follows:

[0088] The intelligent ultrasonic generator is equipped with an air pressure altitude sensor and a platinum resistance water temperature sensor. The air pressure altitude sensor measures a range of 0-6000m with an accuracy of ±10m, and is installed on the outside of the pretreatment water tank to avoid contact with the water source, allowing real-time collection of altitude data in the experimental environment. The platinum resistance water temperature sensor measures a range of -5~100℃ with an accuracy of ±0.1℃, and is inserted into the pretreatment water tank at a depth of 100mm, directly contacting the water source to collect water temperature data in real time. The generator is equipped with a double-input-three-output parameter adaptive chip based on an STM32 single-chip microcomputer. After starting, the chip reads the detection data (altitude, water temperature) of the two sensors every 30s, and automatically outputs control signals by comparing with the built-in parameter mapping table. In this embodiment, the altitude is 2800-3500m and the water temperature is 3-5℃, so the chip will automatically adjust the ultrasonic power to 190W, the ultrasonic frequency to 30kHz, and the stirring speed to 110r / min. After 20 minutes of continuous stirring, the chip automatically controls the generator to stop, and simultaneously triggers the built-in timing module to start the standing time. The standing time is set to 12 minutes, and after the timing is completed, the subsequent filter screen filtering step is prompted. During the stirring process, if the water temperature fluctuates by ±1℃, the chip will adjust the ultrasonic power (±5W) and the stirring speed (±5r / min) in real time.

[0089] Comparative Example 1

[0090] Compared with Example 1, the ordinary vermiculite is used instead of the quaternary ammonium salt modified vermiculite in S1.

[0091] The remaining components, parameters, or steps are the same as those in Example 1.

[0092] Comparative Example 2

[0093] Compared with Example 1, only the quaternary ammonium salt modified vermiculite is retained in the compound modified vermiculite in S1, and the dosage is still 0.3% of the water source mass. The compound freeze-dried powder mixing step is removed.

[0094] The remaining components, parameters, or steps are the same as those in Example 1.

[0095] Comparative Example 3

[0096] Compared with Example 1, the first coating dipping step is directly skipped in S21, and the porous ceramic support is directly immersed in the second coating.

[0097] The remaining components, parameters, or steps are the same as those in Example 1.

[0098] Comparative Example 4

[0099] Comparing with Example 1, the purification column in S31 is only filled with calcium-doped nano-hydroxyapatite coated alumina layer, the filling height is 1.4 m, and the filling amount is 0.12 m³.

[0100] The remaining components, parameters or steps are the same as those in Example 1.

[0101] Comparative Example 5

[0102] Comparing with Example 1, the KH-560 modified diatomite in S2 is replaced by ordinary diatomite (particle size 5-10 μm).

[0103] The remaining components, parameters or steps are the same as those in Example 1.

[0104] Experimental Example

[0105] All the water sources used in the above experimental examples and comparative examples are seasonal ice and snow melt water in the 2800-3500 m region of the western Sichuan plateau, and the water source characteristics are: water temperature 3-5℃, turbidity 500 NTU, containing 0.1-10 μm fine particles (accounting for 62%), pseudomonas (10 4 CFU / mL), pyrrolizidine alkaloids (300-500 Da, concentration 0.8 mg / L), lobo toxin (150-300 Da, concentration 0.5 mg / L), 20-100 nm inorganic-organic composite colloids (concentration 120 mg / L), Pb 2+ (0.1 mg / L), Cd²⁺(0.05 mg / L).

[0106] The turbidity, toxin removal rate, pseudomonas inactivation rate, membrane flux attenuation rate and heavy metal removal rate of the final treated water obtained from Examples 1-2 and Comparative Examples 1-5 are detected, and the test results are shown in Table 1.

[0107] Table 1:

[0108]

[0109] Note: "-" in Table 1 means no experiment is performed.

[0110] From Table 1, it can be seen that:

[0111] The water treated by the three-step process provided by the application in Examples 1-2 has excellent purification indexes: the supernatant turbidity of the final treated water is ≤0.8 NTU, the pyrrolizidine alkaloid removal rate is ≥93.7%, the lobo toxin removal rate is ≥97.6%, the pseudomonas inactivation rate is ≥99.0%, the flux attenuation rate of the composite membrane after 30 d of operation is ≤18.7%, the Pb 2+ removal rate is ≥94.8%, and the Cd2 + The removal rate is ≥93.7%, which can effectively solve the problems of high turbidity, low temperature microorganisms and toxins, composite colloids, small molecule metabolites and heavy metals of ice and snow melt water in the western Sichuan plateau, and the above indexes all meet the drinking water treatment standard. In Example 3, the flocculation settling efficiency is improved by the intelligent ultrasonic generator to adaptively adjust the stirring parameters, so the turbidity is lower and the membrane pollution is lighter.

[0112] In Comparative Example 1, the ordinary vermiculite has low positive charge density, and cannot adsorb the humic molecules with negative charge in water by enhancing the positive charge like the quaternary ammonium salt modified vermiculite, so that the stable dispersion state of fine particle-humic complex suspended matter is difficult to break; at the same time, the ordinary vermiculite lacks adsorption sites for polar impurities, and cannot effectively flocculate fine particles or assist in adsorbing heavy metal ions, ultimately leading to a chain of problems such as increased turbidity, decreased toxin interception rate, aggravated membrane pollution and insufficient heavy metal removal.

[0113] In Comparative Example 2, the high molecular long chain of konjac glucomannan can form a stable flocculation skeleton at low temperature, and the absence of the quaternary ammonium salt modified vermiculite forms a loose and easily broken flocculation, which greatly reduces the settling efficiency, resulting in a large amount of fine particles remaining in the supernatant. The snow fungus polysaccharide can improve the compactness of the flocculation, and the propylene glycol can prevent the freeze-dried powder from absorbing moisture and caking, and the absence of both further weakens the flocculation effect, and also leads to uneven dispersion of the modified vermiculite, which makes the subsequent membrane module easily be penetrated and clogged by fine particles, and at the same time, the auxiliary inhibition effect of the snow fungus polysaccharide on microorganisms is lost, and the inactivation rate decreases.

[0114] In Comparative Example 3, the quaternary ammonium salt modified vermiculite in the first coating can secondarily adsorb the humic substances remaining in S1, and the calcium-doped fly ash can preliminarily intercept inorganic-organic composite colloids, which jointly reduce the burden of the second coating; after skipping the first coating, the humic substances and the composite colloids directly contact the second coating, which leads to the rapid clogging of the mesoporous structure of the second coating by the colloids and the occupation of the adsorption sites by the humic substances, which not only weakens the hydrogen bond adsorption of toxins and the ion exchange of heavy metals, but also accelerates the membrane flux decay, forming a vicious cycle of coating pollution and interception failure.

[0115] In Comparative Example 4, the modified mesoporous carbon is activated by barley straw-fungus carbonization, and the mesoporous structure formed can accurately match the molecular size of 150-300 Da lupine toxin, and the quaternary ammonium salt modification can enhance the adsorption of polar small molecules; only the calcium-doped nano-hydroxyapatite coating alumina layer is retained, the alumina layer can adsorb colloids and part of heavy metals, but lacks mesoporous screening and polar adsorption sites matching small molecule toxins, resulting in that small molecule plant secondary metabolites cannot be effectively intercepted, which becomes a safety hazard in the final effluent.

[0116] In Comparative Example 5, KH-560 modification can form covalent bonds with the surface hydroxyl groups of diatomite through silane coupling agents, enhance the stability of mesoporous structure and surface adsorption activity, and ensure efficient screening of 20-100 nm inorganic-organic composite colloids; the ordinary diatomite surface lacks newly added polar adsorption sites after modification, and the original mesoporous wall surface is not reinforced with silane coupling agents, which leads to easy accumulation of colloids at the mesoporous entrance, resulting in a decrease in screening efficiency. At the same time, due to the lack of polar sites, the toxin cannot be adsorbed through hydrogen bonds, which ultimately leads to a more serious problem of membrane flux decay and a decrease in toxin retention rate.

Claims

1. A precision retention and purification method for water treatment, characterized in that, Includes the following steps: S1. Low-temperature adaptation pretreatment: Add the compound-modified vermiculite to the water source to be treated at 2-10℃, stir thoroughly, filter through a 40-60 mesh stainless steel filter, and take the supernatant. The modified vermiculite is prepared by mixing industrial-grade vermiculite with quaternary ammonium salt and then with konjac glucomannan-propylene glycol-Ganoderma lucidum composite freeze-dried powder. S2. Composite membrane synergistic treatment: S21. Composite membrane preparation: The first coating and the second coating are impregnated sequentially on a porous ceramic support; The first coating comprises quaternary ammonium salt modified vermiculite and calcium-doped fly ash; The second coating comprises KH-560 modified diatomaceous earth, Rhodiola rosea polysaccharide, mercaptopropanesulfonic acid, and calcium-doped nano-hydroxyapatite; S22. Retention operation: Pump the supernatant taken in step S1 into the composite membrane system, and backwash with a flushing solution containing disodium EDTA-citric acid after operation; S3. Deep purification treatment: S31. The permeate from step S22 is passed into the purification column, and the column is provided with a calcium-doped nano-hydroxyapatite coated alumina layer and a modified mesoporous carbon layer from bottom to top. The modified mesoporous carbon is prepared by carbonizing a mixture of barley straw, waste edible fungus residue, and CaO, then activating it with KOH, mixing it with a composite solution of Ganoderma lucidum-propylene glycol-konjac glucomannan-sodium alginate-sea buckthorn pomace, and finally soaking it in a quaternary ammonium salt solution. S32. The permeate from the purification column is irradiated with ultraviolet light to obtain the final effluent.

2. The precision retention and purification method for water treatment according to claim 1, characterized in that, In step S1, the composite-modified vermiculite is prepared by mixing vermiculite with a 0.15-0.25 mol / L quaternary ammonium salt solution at a mass ratio of 1:(18-22); The konjac glucomannan-propylene glycol-Ganoderma lucidum composite freeze-dried powder is obtained by mixing konjac glucomannan, food-grade propylene glycol, and Ganoderma lucidum water extract in a mass ratio of (0.8-1.5):(0.15-0.25):3, followed by vacuum freeze-drying and pulverization at -45~-35℃.

3. The precision retention and purification method for water treatment according to claim 1, characterized in that, In step S1, a smart ultrasonic generator is used to achieve thorough stirring. The power adjustment range of the smart ultrasonic generator is 150-210W, the ultrasonic frequency adjustment range is 25-33kHz, and the generator has a built-in dual-input-three-output parameter adaptive chip. The chip collects the detection data of the altitude sensor and the water temperature sensor in real time, and outputs control signals according to the built-in parameter table to automatically adjust the ultrasonic power, ultrasonic frequency and stirring speed to the corresponding range. The specific adaptation logic is as follows: When the altitude of the treatment scene is between 2800-3500m: if the water temperature of the source to be treated is 2-4℃, the ultrasonic generator will automatically adjust the power to 180-200W and the frequency to 29-32kHz, while simultaneously using a stirring speed of 100-120r / min. After stirring, let it stand for 11-13 minutes. If the water temperature of the source to be treated is 5-10℃, the ultrasonic generator will automatically adjust the power to 160-180W and the frequency to 27-30kHz, while simultaneously using a stirring speed of 90-110r / min. After stirring, let it stand for 10-12 minutes. When the altitude of the treatment environment is between 3501-4500m: if the water temperature is 2-4℃, the ultrasonic generator will automatically adjust the power to 190-210W and the frequency to 31-33kHz, while simultaneously using a stirring speed of 110-130r / min. After stirring, let it stand for 12-14 minutes. If the water temperature is 5-10℃, the ultrasonic generator will automatically adjust the power to 170-190W and the frequency to 29-31kHz, while simultaneously using a stirring speed of 100-120r / min. After stirring, let it stand for 11-13 minutes.

4. The precision retention and purification method for water treatment according to claim 1, characterized in that, In step S21, the specific preparation method of the porous ceramic support is as follows: (1) Remove the meat from the waste yak bones from slaughter in the plateau pastoral area, crush them to a particle size of 4-12 μm, calcine them at 780-820℃ for 1.8-2.2 h, cool them and pass them through a 180-220 mesh sieve to obtain calcined yak bone powder; (2) Mix clay, calcined yak bone powder and deionized water in a mass ratio of 9:(0.5-1.5):(2.8-3.2), knead into a uniform blank, extrude into a column shape, and then fire to obtain the finished product; the finished product has a porous structure.

5. The precision retention and purification method for water treatment according to claim 4, characterized in that, The ceramic support has a length of 150-200 mm and a diameter of 30-40 mm; the porous structure has a pore size of 3-15 μm and a porosity of 35-45%.

6. The precision retention and purification method for water treatment according to claim 1, characterized in that, In step S21, the second coating is prepared by mixing KH-560 modified diatomaceous earth, 3-7% Rhodiola rosea polysaccharide solution, calcium-doped nano-hydroxyapatite, and mercaptopropanesulfonic acid in a mass ratio of 4:(0.8-1.2):(0.2-0.45):(0.004-0.006).

7. The precision retention and purification method for water treatment according to claim 1, characterized in that, In step S31, the inner diameter of the purification column is 80-100 mm; the height ratio of the calcium-doped nano-hydroxyapatite coated alumina layer to the modified mesoporous carbon layer is 1:(7-12).

Images