Wastewater treatment method based on composite oxidation adsorption of ceramic ultrafiltration membrane

Abstract

The invention relates to a ceramic ultrafiltration membrane composite oxidation adsorption wastewater treatment method, which comprises that wastewater to be treated sequentially passes through a ceramic ultrafiltration membrane filtration unit, an oxidation reaction unit and an adsorption purification unit. Wherein the average pore size of the ceramic ultrafiltration membrane is 10-50nm, the transmembrane pressure difference is 0.15-0.4 MPa, the membrane surface flow velocity is 1.5-4.5 m / s, and efficient solid-liquid separation is realized; the ultrafiltration produced water enters an oxidation reaction unit and is subjected to catalytic oxidation with ozone and / or hydrogen peroxide under the action of a supported catalyst, and the dosage of the ozone is 40-100 mg / L; the oxidized effluent is deeply purified through a modified activated carbon adsorption column, and the empty bed flow rate is 10-18 BV / h. The oxidation unit and the adsorption unit can be further integrated to form a series integrated reaction column. The system has the functions of concentrated solution circulating oxidation, gas-water combined backwashing, chemical enhanced cleaning and on-line monitoring and automatic control. The method can effectively remove refractory organic matters and heavy metals, is stable in operation, is excellent in effluent quality, and is suitable for advanced treatment of high-concentration industrial wastewater.

Description

Technical Field

[0001] This invention belongs to the field of industrial wastewater deep treatment technology, specifically relating to a wastewater treatment method using ceramic ultrafiltration membrane composite oxidation adsorption. Background Technology

[0002] With increasingly stringent environmental standards, wastewater from industries such as chemical, printing and dyeing, coal chemical, pharmaceutical, and coking is characterized by high COD (Chemical Oxygen Demand), high color, presence of recalcitrant organic matter and heavy metals, strong biological toxicity, and poor biodegradability. Traditional "physicochemical + biological" processes are insufficient to consistently meet the Class A or even stricter surface water environmental quality standards of the "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants" (GB18918-2002).

[0003] In recent years, ceramic ultrafiltration membranes have been widely used in the pretreatment and advanced treatment of challenging industrial wastewater due to their advantages such as acid and alkali resistance, high temperature resistance, oxidation resistance, strong antifouling ability, high mechanical strength, and long service life. However, single ceramic membranes can only achieve solid-liquid separation and cannot effectively remove dissolved organic pollutants. Advanced oxidation technologies (AOPs) can generate strong oxidizing agents. While oxidant can degrade recalcitrant organic matter, its use alone carries risks such as low oxidant utilization, high operating costs, and the potential generation of secondary pollutants like bromate. Activated carbon adsorption, though capable of deeply removing residual organic matter and heavy metals, suffers from rapid adsorption saturation and regeneration difficulties.

[0004] Existing patents and literature reports mostly involve simple tandem processes such as "ceramic membrane + single oxidation" or "oxidation + ordinary adsorption," which have the following shortcomings:

[0005] 1. The independent setup of each unit results in a large footprint, complex piping connections, and high operating energy consumption;

[0006] 2. Ceramic membranes are susceptible to fouling by organic matter and colloids, requiring frequent cleaning and resulting in rapid flux decay;

[0007] 3. The oxidation and adsorption sections lack synergistic optimization, and residual oxidant can easily cause premature adsorbent failure;

[0008] 4. The concentrate has not been effectively recycled or rendered harmless, posing a risk of secondary pollution.

[0009] Therefore, there is an urgent need for a new wastewater treatment method that deeply couples ceramic ultrafiltration membrane separation, catalytic oxidation, and adsorption purification, while also possessing system integration, automatic control, and concentrate recycling functions, in order to achieve stable, low-cost, and high-efficiency deep purification. Summary of the Invention

[0010] To overcome the shortcomings of existing industrial wastewater deep treatment technologies, such as easy fouling of ceramic ultrafiltration membranes, low oxidant utilization, easy saturation and failure of adsorbents, poor synergy among treatment units, difficulty in harmlessly treating concentrates, large system footprint, and high operating costs, the present invention aims to provide a wastewater treatment method based on ceramic ultrafiltration membrane composite oxidation and adsorption. Through deep coupling of ceramic ultrafiltration membrane separation, catalytic oxidation, and adsorption purification, as well as system integration and optimization, this method achieves efficient and graded removal of recalcitrant organic matter, heavy metals, and colloids. It significantly reduces membrane fouling, improves the synergistic efficiency of oxidation and adsorption units, extends material lifespan, and enables near-zero discharge and recycling of concentrates. Ultimately, it achieves stable operation, high automation, excellent effluent quality, and low overall treatment costs, meeting stringent discharge standards or reuse requirements.

[0011] To achieve the above objectives, the present invention provides a wastewater treatment method using a ceramic ultrafiltration membrane composite oxidation adsorption method, the method comprising:

[0012] The wastewater to be treated is sequentially passed through a ceramic ultrafiltration membrane filtration unit, an oxidation reaction unit, and an adsorption purification unit.

[0013] Solid-liquid separation is performed in the ceramic ultrafiltration membrane filtration unit using a tubular ceramic ultrafiltration membrane with an average pore size of 10-50 nm. The transmembrane pressure difference is 0.15-0.4 MPa and the membrane surface flow velocity is 1.5-4.5 m / s, resulting in ultrafiltration permeate and concentrate.

[0014] The ultrafiltration permeate is fed into an oxidation reaction unit and undergoes a catalytic oxidation reaction with ozone and / or hydrogen peroxide in the presence of a supported catalyst.

[0015] The oxidized effluent is passed into an adsorption purification unit, where residual pollutants are deeply removed by modified adsorption materials to obtain purified effluent.

[0016] Optionally, the ceramic ultrafiltration membrane material is... Composite or Composite structure, support body diameter 6-10mm, membrane thickness 15-30μm, pure water flux 500-1200L / Operating temperature: 20-55℃.

[0017] Optionally, the oxidation reaction unit is an external fixed-bed reactor, and the catalyst is... or The modified particulate carrier has a dry basis loading of 350-550 g / L, an ozone dosage of 40-100 mg / L, a hydrogen peroxide dosage of 10-40 mg / L, an ozone tail gas to liquid volume ratio of 6-10:1, a reaction pH of 6.8-8.2, and a hydraulic retention time of 18-35 min.

[0018] Optionally, the adsorption purification unit adopts a fixed-bed adsorption column, filled with modified coconut shell activated carbon or coal-based columnar activated carbon, with a particle size of 0.8-1.2 mm, an iodine value of 1200-1400 mg / g, and a specific surface area of ​​[missing information]. The empty bed contact time is 4-8 minutes, and the running empty bed flow rate is 10-18 BV / h.

[0019] Optionally, the oxidation reaction unit and the adsorption purification unit are integrated to form a series integrated reaction column. The column consists of a catalytic oxidation zone (0.5-0.8m high) and an adsorption zone (1.2-1.8m high) from bottom to top. The molar ratio of ozone to hydrogen peroxide is 1:0.4-1:0.6, and the total residence time is 20-30 min.

[0020] Optionally, the ceramic ultrafiltration membrane filtration unit employs a combination of gas-water backwashing and chemically enhanced backwashing, with a backwash gas intensity of 9-11 L / m³. Backwash water intensity 18-22L / The backwashing cycle is 8-20 hours; chemically enhanced backwashing uses a mixture of 0.6-0.9wt% NaOH + 300-450mg / L NaClO at a temperature of 55-62℃ for 40-50 minutes.

[0021] Optionally, the system is equipped with sensors for online monitoring of transmembrane pressure difference, ORP, TOC and pH. When the transmembrane pressure difference is ≥0.35MPa or the ORP is lower than the set value, the ozone dosage is automatically increased by 15-20% or the membrane chemical cleaning program is started.

[0022] Optionally, the concentrate produced by the ceramic ultrafiltration membrane is refluxed to the oxidation reaction unit for cyclic catalytic oxidation, with a circulation rate of 4-7 times. After circulation, the concentrate is then introduced into the subsequent concentration or solidification unit.

[0023] Optionally, the ceramic ultrafiltration membrane filtration unit operates in constant flux mode, with the flux controlled between 80-250 L / m³. The transmembrane pressure difference is maintained by adjusting the speed of the inlet pump through frequency conversion.

[0024] Optionally, the ozone is added through a titanium alloy microporous aeration disc or a Venturi jet injector, with an average bubble diameter ≤800μm and a gas-liquid mass transfer efficiency ≥85%.

[0025] This invention achieves highly efficient, staged removal of recalcitrant organic matter, heavy metals, and colloids through the deep coupling of ceramic ultrafiltration membrane separation, catalytic oxidation, and adsorption purification. It overcomes the problem of traditional processes failing to consistently meet standards, resulting in excellent and stable effluent quality. The integrated design of the oxidation and adsorption units, along with a concentrated liquid recycling oxidation process, significantly reduces system footprint, piping complexity, and energy consumption, while improving oxidant utilization, preventing damage to adsorbent materials from residual oxidant, and extending adsorbent lifespan. Combined gas-water backwashing, an optimized chemical-enhanced cleaning strategy, and an online monitoring and automatic control system effectively mitigate ceramic membrane fouling, maintain a high flux recovery rate, and extend membrane module lifespan. The recycling of concentrated liquid to the oxidation unit for mineralization achieves complete destruction of recalcitrant substances and near-zero system emissions, fundamentally eliminating the risk of secondary pollution. The overall process is stable, highly automated, and significantly cheaper than existing technologies, making it particularly suitable for the deep treatment and reuse of high-concentration, highly toxic industrial wastewater. Attached Figure Description

[0026] Figure 1 The present invention provides a flow chart of a wastewater treatment method using ceramic ultrafiltration membrane composite oxidation adsorption. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0028] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; in the description of this application, unless otherwise stated, "multiple" means two or more.

[0029] To more clearly illustrate the technical solution of the present invention, the present invention will be described in detail below with reference to specific embodiments, but it should not be construed as a limitation on the scope of protection of the present invention.

[0030] like Figure 1As shown, this embodiment demonstrates the continuous 30-day deep treatment of mixed wastewater from a chemical industrial park (influent COD 1650-2100 mg / L, color 280-350 times, containing benzene compounds, phenols and trace heavy metals). The effluent COD was consistently below 50 mg / L, the color was less than 10 times, the transmembrane pressure difference of the system increased slightly, and the operation was stable, achieving efficient and low-cost deep purification.

[0031] Step S01: The wastewater to be treated is sequentially passed through a ceramic ultrafiltration membrane filtration unit, an oxidation reaction unit, and an adsorption purification unit.

[0032] Wastewater first passes through a screen to remove large floating particles, then enters an equalization tank for homogenization and equalization, and is continuously fed into a ceramic ultrafiltration membrane filtration unit by a variable frequency booster pump. The produced water flows by gravity into an intermediate water tank, and is then pumped to an oxidation reaction unit. The oxidized effluent then flows by gravity into an adsorption purification unit, forming a continuous series operation throughout the entire process. The entire system is automatically coordinated and controlled by a PLC.

[0033] Step S02: Solid-liquid separation is performed in the ceramic ultrafiltration membrane filtration unit using a tubular ceramic ultrafiltration membrane with an average pore size of 10-50 nm. The transmembrane pressure difference is 0.15-0.4 MPa and the membrane surface flow rate is 1.5-4.5 m / s to obtain ultrafiltration permeate and concentrate.

[0034] Specifically, 19 channels are selected. The composite tubular ceramic ultrafiltration membrane has an average pore size of 30nm and an effective area of ​​5m² per membrane. A total of eight membranes are installed to form one membrane module. The system employs a cross-flow filtration + partial recirculation mode, with a recirculation pump frequency of 42-48Hz, maintaining a membrane surface velocity of 3.5-4.0m / s. The inlet pressure is 0.38MPa, the outlet pressure is 0.18MPa, and the actual transmembrane pressure difference is stable at 0.20-0.26MPa. Furthermore, the operating flux is controlled at 160-200L / L. The water production rate is 91-93%, the turbidity of the ultrafiltration water is ≤0.15NTU, the suspended solids are almost completely removed, the COD removal rate is 20-28%, the solid content of the concentrate is increased to about 4%, and the concentrate is periodically discharged to the subsequent treatment process.

[0035] Step S03: The ultrafiltration permeate is fed into the oxidation reaction unit and undergoes a catalytic oxidation reaction with ozone and / or hydrogen peroxide in the presence of a supported catalyst.

[0036] Specifically, the ultrafiltration permeate is uniformly fed into a vertical fixed-bed catalytic oxidation reactor via a booster pump, and the reactor is filled with... A composite supported catalyst is used. Ozone is generated by an ozone generator and uniformly diffused through a bottom titanium alloy microporous aeration disc, with an actual dosage of 75-90 mg / L. Simultaneously, 30-35 mg / L of hydrogen peroxide is added via a corrosion-resistant metering pump, maintaining a gas-liquid volume ratio of 7-9:1. The pH of the reaction zone is maintained at 7.2-7.8 using an automatic acid / alkali addition device, and the hydraulic retention time is approximately 25-30 minutes. Understandably, the hydroxyl radicals generated on the catalyst surface effectively open and break the chains of large, recalcitrant aromatic compounds, achieving a total COD removal rate of 60-70% and a color removal rate exceeding 92% in the oxidation stage.

[0037] Step S04: The oxidized effluent is passed into the adsorption purification unit, where residual pollutants are deeply removed by the modified adsorption material to obtain purified effluent.

[0038] Specifically, the oxidized effluent flows by gravity into a two-stage series fixed-bed adsorption column. Each column is filled with coconut shell granular activated carbon modified by nitric acid and high temperature (particle size 0.8-1.2 mm, iodine value 1350 mg / g, specific surface area...). The operating empty bed flow rate is 13-15 BV / h, and the single-column contact time is approximately 5.5 min. Residual small-molecule organic matter, heavy metal ions, and trace oxidation byproducts are deeply adsorbed, resulting in a final effluent COD of 35-48 mg / L and a color 4-8 times higher, meeting the park's reclaimed water requirements. Furthermore, when the COD at the outlet of the first-stage adsorption column approaches 50 mg / L, it automatically switches to a standby column to ensure uninterrupted system operation. The saturated activated carbon can be thermally regenerated offline for reuse.

[0039]

[0040] Table 1 - Average water quality indicators (mg / L, excluding pH and color) for 30 consecutive days of operation in Example 1

[0041] In summary, as shown in Table 1, this invention achieves a total COD removal rate of over 97.5% through deep coupling of ceramic ultrafiltration membrane, catalytic oxidation, and adsorption. The effluent indicators are superior to the Class IV standard for surface water and can be directly reused.

[0042] This embodiment achieves precise, graded removal of suspended solids, colloids, recalcitrant organic matter, heavy metals, and residual pollutants from wastewater by sequentially coupling a ceramic ultrafiltration membrane filtration unit, an oxidation reaction unit, and an adsorption purification unit in series. The ultrafiltration membrane efficiently traps large particles and emulsified substances, significantly reducing the load on subsequent oxidation and adsorption units. It catalytically oxidizes and deeply mineralizes large molecular organic matter and improves biodegradability. The adsorption unit selectively and deeply purifies small molecule residual pollutants, resulting in excellent and stable effluent quality. The overall COD removal rate reaches over 97%, and indicators such as color, turbidity, and heavy metals are significantly reduced. At the same time, the process flow is simple, and the inter-unit synergy is strong, avoiding the defects of single technology such as low oxidant utilization, rapid membrane fouling, and early adsorption saturation. The system operates stably, has strong shock resistance, and a high degree of automation. The treatment cost is significantly lower than that of traditional multi-unit independent processes. It is particularly suitable for the deep treatment and reuse of high-concentration and highly toxic industrial wastewater from chemical, printing and dyeing, coal chemical, and pharmaceutical industries, achieving efficient, economical, and stable environmental protection effects.

[0043] Based on Example 1, this embodiment further defines the material and structural parameters of the ceramic ultrafiltration membrane. It is tested by continuous operation for 45 days on mixed wastewater from the same chemical industrial park. The results show that the membrane module has extremely slow flux decay under high oil and high hardness conditions. The transmembrane pressure difference only increased by 0.08 MPa within 45 days. The membrane cleaning interval was extended to more than 20 days. The effluent quality was comparable to that of Example 1, proving that the selected membrane material and structural parameters have excellent fouling resistance and long lifespan characteristics.

[0044] Solid-liquid separation is performed in the ceramic ultrafiltration membrane filtration unit using a tubular ceramic ultrafiltration membrane with an average pore size of 10-50 nm. The transmembrane pressure difference is 0.15-0.4 MPa and the membrane surface flow rate is 1.5-4.5 m / s, resulting in ultrafiltration permeate and concentrate.

[0045] The ceramic ultrafiltration membrane material is Composite or Composite structure, support body diameter 6-10mm, membrane thickness 15-30μm, pure water flux Operating temperature: 20-55℃.

[0046] Specifically, this embodiment selects A composite 19-channel tubular ceramic ultrafiltration membrane with a support inner diameter of 8 mm, a separation layer thickness of 22 μm, and an average pore size of 28 nm. The measured pure water flux of the new membrane is 980 L / m³. A single membrane module consists of 10 membranes connected in parallel, with a total effective membrane area of ​​[missing information]. Design processing capacity .

[0047] Furthermore, the system adopts a constant flux operation mode, with the actual flux set... By adjusting the speed of the inlet pump and the circulation pump using frequency converters, the membrane surface flow velocity is kept stable at 3.8-4.1 m / s, and the inlet water temperature is controlled at 32-38℃ (not exceeding 52℃ in summer). The initial transmembrane pressure difference is 0.18 MPa, which increases to 0.26 MPa after 45 days.

[0048] Understandably, The composite material has a surface zeta potential of approximately -28mV at pH=7, exhibiting strong hydrophilicity and resistance to organic matter adsorption. The thermal expansion coefficients of the support and separation layer are matched, and no microcracks are generated in the membrane tube under temperature fluctuations of 20-55℃. The structural design with an inner diameter of 8mm and a membrane thickness of 22μm ensures both high mechanical strength and sufficient flow channels, reducing pump energy consumption during cross-flow operation.

[0049] Furthermore, even under shock conditions where the oil content occasionally reaches as high as 180 mg / L, the oil fouling layer on the membrane surface forms extremely slowly, and the flux maintenance rate remains above 92%, fully demonstrating that this combination of material and structural parameters has significant advantages in anti-fouling and long-term stable operation in challenging industrial wastewater environments. The operating parameters and effluent performance of the subsequent oxidation and adsorption units are completely consistent with those of Example 1.

[0050] Based on Example 1, this embodiment further specifies the oxidation reaction unit as an external fixed-bed reactor and uses a preferred catalyst and precise dosing parameters to continuously treat wastewater containing high concentrations of nitrobenzene and chlorophenols (COD 2800-3200 mg / L) for 60 days. The COD removal rate of the oxidation stage is stable at 68-74%, and the biodegradability (B / C) of the effluent is improved from 0.12 to over 0.48. The system energy consumption is reduced by about 28% compared with conventional ozone oxidation alone, proving that the specific oxidation unit structure and parameters have higher free radical yield and oxidant utilization efficiency.

[0051] The ultrafiltration permeate is fed into an oxidation reaction unit and undergoes a catalytic oxidation reaction with ozone and / or hydrogen peroxide in the presence of a supported catalyst.

[0052] The oxidation reaction unit adopts an external fixed-bed reactor, and the catalyst is... or The modified particulate carrier has a dry basis loading of 350-550 g / L, an ozone dosage of 40-100 mg / L, a hydrogen peroxide dosage of 10-40 mg / L, an ozone tail gas to liquid volume ratio of 6-10:1, a reaction pH of 6.8-8.2, and a hydraulic retention time of 18-35 min.

[0053] Specifically, in this embodiment, the oxidation reaction unit uses two stainless steel fixed-bed reactors operating in parallel (each unit is Φ1200mm×H4500mm, with an effective volume of...). ), internal filling Composite particulate catalyst (particle size 1.2-1.6 mm, dry basis loading 480 g / L), the catalyst is composed of The carrier was prepared by impregnation-calcination method with an Mn / Ti molar ratio of 0.4.

[0054] Furthermore, the ultrafiltration permeate is pumped by a booster pump... The flow rate is evenly distributed into the bottom of the two reactors. Ozone is generated by the liquid oxygen source ozone generator, with the actual added concentration controlled at 82-92 mg / L. It is evenly released through the bottom titanium alloy microporous aeration disc. Hydrogen peroxide (27.5%) is added synchronously and quantitatively through two corrosion-resistant metering pumps, with an addition amount of 28-32 mg / L. The volume ratio of ozone tail gas to liquid is precisely controlled at 8.2-8.8:1.

[0055] Understandably, the pH in the reaction zone is maintained at 7.3-7.7 using an online pH meter and an automatic dosing system for dilute sulfuric acid / sodium hydroxide. The actual hydraulic retention time is 26-29 minutes. A tail gas destroyer is installed at the top of the reactor to control the residual ozone concentration. .

[0056] Furthermore, continuous operation monitoring showed that a high concentration of [something] was continuously generated on the catalyst surface. The oxidation section achieved a p-nitrobenzene removal rate >96% and a p-2,4-dichlorophenol removal rate >99%, with the effluent B / C ratio remaining stable at around 0.50, significantly reducing the load on subsequent adsorption units. Within 60 days, without catalyst replacement or regeneration, the reactor pressure differential increased by only 0.03 MPa, demonstrating that this external fixed-bed structure and parameter combination possesses excellent catalytic activity, mass transfer efficiency, and long-term operational stability. The operating parameters and effects of the subsequent ceramic ultrafiltration membrane filtration unit and adsorption purification unit remained consistent with those in Example 1.

[0057] Based on Example 1, this embodiment further specifies the adsorption purification unit as a fixed-bed adsorption column, selects high-performance modified activated carbon, and strictly controls the adsorption operation parameters. It performs continuous deep treatment on dyeing and printing wastewater (COD 120-180mg / L and color 80-120 times after pretreatment) for 90 days. The effluent COD is stable at ≤38mg / L and color is ≤6 times. The single cycle operation time is more than 28 days. The utilization rate of activated carbon is significantly improved, which proves that the structure and parameters of this adsorption unit have extremely high adsorption capacity and shock resistance.

[0058] The oxidized effluent is passed into an adsorption purification unit, where residual pollutants are deeply removed by modified adsorption materials to obtain purified effluent.

[0059] The adsorption and purification unit employs a fixed-bed adsorption column, filled with modified coconut shell activated carbon or coal-based columnar activated carbon, with a particle size of 0.8-1.2 mm, an iodine value of 1200-1400 mg / g, and a specific surface area of ​​[missing information]. The empty bed contact time is 4-8 minutes, and the running empty bed flow rate is 10-18 BV / h.

[0060] Specifically, in this embodiment, the adsorption purification unit consists of three columns connected in series and parallel (two in use and one as a backup), with each column having an inner diameter of... Height 4000mm, effective filling volume The activated carbon, filled with coconut shell granules modified by phosphoric acid and high-temperature steam, has a measured particle size of 1.0 mm, an iodine value of 1380 mg / g, and a specific surface area of ​​[missing information]. Bulk density .

[0061] Furthermore, the effluent from the oxidation process flows by gravity from the top of the column downwards into the operating column, with a designed treatment capacity of... The actual operating empty bed flow rate is 14.5-15.5 BV / h, corresponding to an empty bed contact time of approximately 5.8 minutes. The system precisely controls the flow rate of each column through an inlet electromagnetic flowmeter and an automatic valve station, with flow fluctuations ≤ ±3%.

[0062] Understandably, the surface of modified activated carbon is rich in phosphate groups and oxygen-containing functional groups, exhibiting extremely strong selective adsorption capacity for residual anthraquinone, azo dye intermediates, and small molecule aromatic compounds. The adsorption capacity of heavy metals was also significantly improved.

[0063] Furthermore, continuous monitoring for 90 days showed that the COD at the outlet of the first column only slowly rose to 45 mg / L between days 26 and 28. At this point, the system automatically switched to the standby column. After offline thermal regeneration of the saturated column (activation with steam at 850℃ for 6 hours), the iodine value recovered to above 1320 mg / g, allowing for recycling. The final effluent COD was 30-38 mg / L, with a color 4-6 times higher, meeting the most stringent reclaimed water standards. No abrupt adsorption breakthrough occurred throughout the entire cycle, proving that the combination of particle size, iodine value, specific surface area, and operating empty bed flow rate achieved the optimal balance between adsorption capacity and treatment efficiency, greatly extending the adsorbent replacement cycle and reducing operating costs. The operating parameters and effects of the upstream ceramic ultrafiltration membrane filtration unit and oxidation reaction unit remained consistent with those in Example 1.

[0064] Based on Example 1 above, this embodiment further integrates the oxidation reaction unit and the adsorption purification unit to form a series integrated reaction column, which continuously treats coking biochemical tailwater (COD 260-380mg / L, containing naphthalene, quinoline, cyanide and phenols) for 150 days. The effluent COD is stable at ≤38mg / L. The footprint is reduced by 42% compared to the split type, and the operating energy consumption and reagent consumption are significantly reduced. This proves that the integrated structure achieves a high degree of synergy between oxidation and adsorption and a compact process.

[0065] The ultrafiltration permeate is fed into an oxidation reaction unit and undergoes a catalytic oxidation reaction with ozone and / or hydrogen peroxide in the presence of a supported catalyst.

[0066] The oxidized effluent is passed into an adsorption purification unit, where residual pollutants are deeply removed by modified adsorption materials to obtain purified effluent.

[0067] The oxidation reaction unit and the adsorption purification unit are integrated to form a series integrated reaction column. The column consists of a catalytic oxidation zone (0.5-0.8m high) and an adsorption zone (1.2-1.8m high) from bottom to top. The molar ratio of ozone to hydrogen peroxide is 1:0.4-1:0.6, and the total residence time is 20-30min.

[0068] Specifically, a monolithic 304 stainless steel-lined PTFE integrated reaction column (Φ1600mm×H5100mm) is used, with a lower catalytic oxidation zone height of 0.65m, and is filled with... Composite particulate catalyst (dry basis loading 490 g / L); the upper adsorption zone is 1.55 m high and filled with nitric acid-high temperature composite modified coconut shell activated carbon (particle size 1.0 mm, iodine value 1370 mg / g).

[0069] Furthermore, the permeate from the ceramic ultrafiltration membrane enters continuously from the bottom of the column, with ozone dosage of 88 mg / L and hydrogen peroxide dosage of 33 mg / L (combined molar ratio 1:0.51), added through a Venturi jet injector at the bottom of the column and a titanium microporous aeration disc, with a gas-liquid volume ratio of 8.4:1, an actual total hydraulic retention time of 27 min (approximately 9.5 min in the oxidation zone and approximately 17.5 min in the adsorption zone), and a reaction pH of 7.4-7.8.

[0070] Understandably, the integrated design allows the hydroxyl radicals and residual ozone generated in the oxidation zone to be immediately utilized by the adsorption layer during the ascent process, and the intermediate oxidation products are also rapidly adsorbed to drive the reaction forward, forming a significant oxidation-adsorption synergistic effect, while avoiding the ineffective oxidation of the upper activated carbon by residual ozone.

[0071] Furthermore, during 150 days of continuous operation, the pressure differential of the integrated column increased by only 0.045 MPa, the effluent COD was 30-38 mg / L, and the levels of cyanide, phenols, and polycyclic aromatic hydrocarbons were all below the detection limits. The ozone concentration in the top tail gas was also low. The adsorption layer showed no obvious hardening, which fully demonstrates that the high degree of distribution and compounding ratio achieved optimal synergistic matching and long-term stable operation.

[0072] In some embodiments, the specific parameters of the combined gas-water backwashing and chemically enhanced backwashing of the ceramic ultrafiltration membrane are further defined. The deep treatment of coal chemical concentrated brine with high oil and colloid content (influent SS 120-280mg / L, oil 30-85mg / L) was carried out for 180 consecutive days. The membrane flux recovery rate was ≥99% each time, the chemical cleaning cycle was extended to 18-22 days, and the transmembrane pressure difference rise rate was only 1 / 3 of that of the conventional cleaning method. This proves that the cleaning scheme can significantly reduce irreversible fouling and greatly extend the actual life of the membrane module.

[0073] Solid-liquid separation is performed in the ceramic ultrafiltration membrane filtration unit using a tubular ceramic ultrafiltration membrane with an average pore size of 10-50 nm. The transmembrane pressure difference is 0.15-0.4 MPa and the membrane surface flow rate is 1.5-4.5 m / s, resulting in ultrafiltration permeate and concentrate.

[0074] The ceramic ultrafiltration membrane employs a combination of gas-water backwashing and chemically enhanced backwashing, with varying backwash gas intensity. Backwash water intensity The backwashing cycle is 8-20 hours; chemically enhanced backwashing uses a mixture of 0.6-0.9wt% NaOH + 300-450mg / L NaClO at a temperature of 55-62℃ for 40-50 minutes.

[0075] Specifically, this embodiment still uses the same methods as Embodiment 2. Composite 19-channel ceramic ultrafiltration membrane (average pore size 30nm), with 10 membrane modules connected in parallel in a single set.

[0076] Furthermore, the system is set to automatically perform a combined air-water backwash every 16 hours of operation: first, an air flush for 30 seconds (intensity...). (Pressure 0.12MPa), re-air and water backflushing simultaneously for 90 seconds (air) ,water Finally, pure water is discharged for 30 seconds, with a total duration of about 3 minutes and a water production loss of less than 1.5%.

[0077] Understandably, when the transmembrane pressure difference rises to 0.35 MPa or the flux recovery rate is less than 95% after 5 consecutive air-water backwashes, the system automatically switches to a chemically enhanced backwash program: first, 55℃ pure water is used to replace the residual liquid in the membrane tube, then a mixture of 0.8wt% NaOH + 400mg / L NaClO (pH≈12.8) is circulated and pumped for 20 minutes, followed by static soaking for 45 minutes. Finally, the system is rinsed with 60℃ pure water until the effluent pH is <9 and the residual chlorine is <0.05mg / L. The entire chemical cleaning process takes about 2.5 hours.

[0078] Furthermore, the 180-day continuous operation record shows that a total of 9 chemical cleanings were performed, with a flux recovery rate of 99.2%-99.8% after each cleaning. There was no obvious oil or biological slime residue on the membrane surface, proving that the combination of gas strength, water strength, chemical concentration, temperature and soaking time achieved complete removal of organic matter, oil, colloids and biological contaminants, while causing no corrosive damage to the ceramic membrane material.

[0079] Based on the aforementioned Examples 1-6, this embodiment further equips a complete online monitoring and automatic control system to continuously treat the biochemical effluent of pharmaceutical wastewater (COD fluctuating 650-1400 mg / L, ammonia nitrogen 80-220 mg / L) for 200 days. When the influent load suddenly increases by 45%, the system automatically completes the switching between ozone dosing and cleaning programs within 12 minutes. The effluent COD remains stable at ≤45 mg / L, and the maximum transmembrane pressure difference only rises to 0.33 MPa, proving that this monitoring and control strategy can achieve rapid response and stable operation under all working conditions.

[0080] The system is equipped with sensors for online monitoring of transmembrane pressure difference, ORP, TOC and pH. When the transmembrane pressure difference is ≥0.35MPa or the ORP is lower than the set value, the ozone dosage is automatically increased by 15-20% or the membrane chemical cleaning program is started.

[0081] Specifically, the system installs high-precision online instruments in the following key locations:

[0082] One differential pressure transmitter (accuracy 0.075%FS) is installed at both the inlet and outlet of the ceramic ultrafiltration membrane to calculate and display the transmembrane pressure difference in real time.

[0083] A platinum electrode ORP meter (response time < 8s) is installed in the middle of the oxidation reaction zone.

[0084] An online TOC analyzer with UV-Vis spectroscopy (measurement cycle 90s) is installed in the oxidation effluent pipeline.

[0085] One pH meter is installed in both the ultrafiltration permeate and oxidation zones. All signals are connected to a Siemens S7-1500 PLC and a WinCC host computer.

[0086] Furthermore, the control logic is set as follows:

[0087] 1) When the transmembrane pressure difference continuously increases by ≥0.04MPa or the absolute value is ≥0.35MPa within 10 minutes, the PLC immediately shuts off the product water valve and performs one enhanced air-water backwash (air intensity) first. Water strength If the problem persists, the chemical cleaning procedure described in Example 6 will be automatically initiated within 30 minutes.

[0088] 2) When the ORP is below 680mV (empirical threshold) within 5 minutes, the system will automatically increase the ozone dosage by 18% according to the current flow rate ratio, and at the same time increase the hydrogen peroxide according to the compound ratio until the ORP rises back to above 720mV.

[0089] 3) When TOC exceeds 50 mg / L for three consecutive measurement cycles, the ozone level will be increased by 18% and an alarm will be issued to prompt manual verification.

[0090] Understandably, during the 200-day operation period, the transmembrane differential pressure protection was triggered 7 times (all of which were restored by enhanced air-water backwashing), and the ORP low automatic ozone dosing was triggered 42 times (each lasting an average of 28 minutes). There was no instance of COD exceeding the standard in the effluent, and the system was unattended for more than 95% of the time. This fully demonstrates that the monitoring points and threshold settings can accurately capture the precursors of membrane fouling and oxidation capacity decline, achieve preventive control, and ensure long-term stable compliance of the entire process.

[0091] In some embodiments, the high-rate circulating oxidation treatment process of the concentrate is further defined to continuously operate with zero discharge for 240 days on high-salt and high-concentration coal chemical wastewater (influent COD 4200-5800mg / L, salt content 8%-10%). The cumulative COD removal rate of the circulating section is >92%, and the final COD of the concentrate is reduced to below 420mg / L. The system has no waste liquid discharge, which proves that the concentrate circulating mineralization scheme can completely solve the secondary pollution problem and achieve true zero discharge.

[0092] The concentrate produced by the ceramic ultrafiltration membrane is refluxed to the oxidation reaction unit for cyclic catalytic oxidation, with a circulation rate of 4-7 times. After circulation, the concentrate is then introduced into the subsequent concentration or solidification unit.

[0093] Specifically, the concentrated liquid (solid content 4.5%-6%) produced by the ceramic ultrafiltration membrane filtration unit is not discharged externally, but is sent in full to the inlet of the oxidation reaction unit through a special corrosion-resistant centrifugal pump. It is then mixed with the ultrafiltration permeate at a circulation ratio of 5.8:1 and enters the oxidation reaction zone described in Example 3 or Example 5.

[0094] Furthermore, the circulation pump flow rate is controlled by the frequency converter in conjunction with the ultrafiltration permeate flow rate, with the actual circulation ratio remaining stable at 5.5-6.2 times. Within the oxidation zone, the circulating liquid comes into full contact with freshly added ozone (95 mg / L) and hydrogen peroxide (36 mg / L), continuously mineralizing recalcitrant macromolecules, resulting in a COD reduction of approximately 18%-22% per cycle.

[0095] Understandably, after 5-6 cycles, the residual organic matter in the concentrate has been largely destroyed. When mixed with water, the COD drops to 380-420 mg / L, the color is less than 20 times, and the volume is reduced to about 1 / 6 of the original concentrated liquid volume. Then it enters the high-temperature multi-effect evaporation crystallization unit, and finally produces mixed salts and condensate. The condensate is recycled for system makeup water.

[0096] Furthermore, during 240 days of continuous operation, there was no significant scaling in the circulation pipeline and oxidation zone, the catalyst activity did not decrease, and the final miscellaneous salt yield was only 0.8%-1.1% of the influent. The system achieved zero liquid discharge, and all effluent met the reuse standards. This fully demonstrates that the matching of this circulation ratio with the subsequent concentration and solidification process can efficiently and economically achieve full-scale treatment of high-concentration, recalcitrant wastewater.

[0097] In some embodiments, a constant flux operation mode and variable frequency linkage control are further adopted to continuously and stably operate the deep treatment of dyeing and printing wastewater (influent COD fluctuation 1100-2600mg / L, color 180-420 times) for 300 days. The actual flux of the ceramic membrane is always kept within ±4% of the set value, and the transmembrane pressure difference rise rate is only 0.0008MPa / h. The system does not require frequent manual adjustment, which proves that the constant flux operation mode can achieve precise control of membrane fouling and long-term extremely stable operation.

[0098] The ceramic ultrafiltration membrane filtration unit operates in a constant flux mode, with the flux controlled between 80-250L. The transmembrane pressure difference is maintained by adjusting the speed of the inlet pump through frequency conversion.

[0099] Specifically, this embodiment still uses the same methods as in Embodiment 2. Composite ceramic ultrafiltration membrane module (10 units in parallel, total membrane area) The system is set to a constant permeate flow rate of 185 L / L. .

[0100] Furthermore, a high-precision electromagnetic flow meter (accuracy 0.5%) is installed at the product water end, providing real-time feedback signals to the PLC. Based on the deviation between the actual product water flow rate and the set value, the PLC uses a PID algorithm (P=2.8, I=45s, D=0) to continuously adjust the frequency converters of the inlet pump and circulation pump (range 25-50Hz), with an adjustment cycle ≤8 seconds, ensuring the product water flux remains stable at 182-188 L / min. between.

[0101] Understandably, in constant flux mode, the initial transmembrane pressure difference is only 0.16 MPa. As fouling slowly accumulates, the system automatically and gradually increases the pump speed to maintain the permeate flow until the transmembrane pressure difference approaches 0.34 MPa, at which point the chemical cleaning described in Example 6 is automatically triggered. After cleaning, the pump frequency automatically returns to its initial value, and the transmembrane pressure difference recovers to approximately 0.17 MPa, forming a stable "slow climb-cleaning-rapid drop" cycle.

[0102] Furthermore, the 300-day operation record shows that: chemical cleaning was performed 14 times, the flux recovery rate after each cleaning was ≥99.3%, the average annual increase rate of transmembrane pressure difference was only 0.0008 MPa / h, far lower than the 0.002-0.003 MPa / h of constant pressure mode, the daily fluctuation of permeate volume was <2.5%, the system achieved a high degree of automation and extremely stable operation, the influent water quality and quantity of the subsequent oxidation and adsorption units were extremely stable, and the effluent indicators were better than those of Example 1.

[0103] In some embodiments, the ozone-specific dosing equipment and process parameters are further defined to continuously treat the concentrated wastewater from a petrochemical reverse osmosis system (COD 380-520 mg / L, containing petroleum hydrocarbons, benzene compounds, and a small amount of bromide) for 360 days. The measured ozone mass transfer efficiency is 88.3%-91.2%, and the average ozone concentration in the exhaust gas is lower than [previous value]. The bromate formation was <8μg / L, and all effluent indicators were better than the reuse standard, proving that this ozone addition method can achieve extremely high gas-liquid mass transfer efficiency and extremely low by-product risk.

[0104] The ozone is added through a titanium alloy microporous aeration disc or a Venturi jet injector, with an average bubble diameter ≤800μm and a gas-liquid mass transfer efficiency ≥85%.

[0105] Specifically, in this embodiment, ozone addition adopts a two-stage series connection of "Venturi jet + titanium alloy microporous aeration disc".

[0106] Stage 1: The ultrafiltration permeate first passes through a DN150 in-line titanium Venturi jet injector with a throat diameter of 28mm. The air intake is automatically adjusted to control the average diameter of the bubbles at the jet injector outlet at 600-750μm, with an initial mass transfer efficiency of approximately 68%.

[0107] Secondary stage: The water from the jet injector enters the bottom of the oxidation reaction zone, where four Φ500mm sintered titanium alloy microporous aeration discs (average pore diameter 25μm, wall thickness 5mm, pressure resistance 0.6MPa) are arranged to further cut the remaining large-diameter bubbles to an average diameter ≤420μm. Finally, the overall gas-liquid mass transfer efficiency is stabilized at 88.3%-91.2%.

[0108] Furthermore, the ozone generator adopts a high-frequency, high-voltage discharge type (liquid oxygen source, gas concentration 11-13wt%), with a dosage of 85-95mg / L. It is controlled by a mass flow meter linked to pipeline pressure. An electromagnetic proportional valve is installed at the ejector intake. The PLC fine-tunes the intake volume in real time based on the ORP of the oxidation zone to ensure that the ozone concentration in the exhaust gas remains below a certain level. The exhaust gas is catalytically destroyed before being emitted into the atmosphere.

[0109] Understandably, the two-stage dosing extends the residence time of bubbles in the liquid to over 18 seconds, increasing ozone utilization by 31% compared to traditional single aeration discs. Simultaneously, the microbubbles significantly reduce the conversion rate of bromide ions to bromate. After 360 days of continuous monitoring, the average bromate level in the effluent was only 6.2 μg / L, far below the 10 μg / L standard. The system operates quietly without any gas explosions, and after one year of use, the aeration discs and ejectors showed no significant scaling, fully demonstrating that this dosing method combines high efficiency, safety, and long lifespan under complex wastewater conditions characterized by high bromine and high salinity.

[0110] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A wastewater treatment method using a ceramic ultrafiltration membrane composite oxidation adsorption, characterized in that, Includes the following steps: The wastewater to be treated is sequentially passed through a ceramic ultrafiltration membrane filtration unit, an oxidation reaction unit, and an adsorption purification unit. Solid-liquid separation is performed in the ceramic ultrafiltration membrane filtration unit using a tubular ceramic ultrafiltration membrane with an average pore size of 10-50 nm. The transmembrane pressure difference is 0.15-0.4 MPa and the membrane surface flow velocity is 1.5-4.5 m / s, resulting in ultrafiltration permeate and concentrate. The ultrafiltration permeate is fed into an oxidation reaction unit and undergoes a catalytic oxidation reaction with ozone and / or hydrogen peroxide in the presence of a supported catalyst. The oxidized effluent is passed into an adsorption purification unit, where residual pollutants are deeply removed by modified adsorption materials to obtain purified effluent.

2. The wastewater treatment method using ceramic ultrafiltration membrane composite oxidation adsorption as described in claim 1, characterized in that, The ceramic ultrafiltration membrane material is Composite or Composite structure, support body diameter 6-10mm, membrane thickness 15-30μm, pure water flux 500-1200L / Operating temperature: 20-55℃.

3. The wastewater treatment method using ceramic ultrafiltration membrane composite oxidation adsorption as described in claim 1, characterized in that, The oxidation reaction unit adopts an external fixed-bed reactor, and the catalyst is... or The modified particulate carrier has a dry basis loading of 350-550 g / L, an ozone dosage of 40-100 mg / L, a hydrogen peroxide dosage of 10-40 mg / L, an ozone tail gas to liquid volume ratio of 6-10:1, a reaction pH of 6.8-8.2, and a hydraulic retention time of 18-35 min.

4. The wastewater treatment method using ceramic ultrafiltration membrane composite oxidation adsorption as described in claim 1, characterized in that, The adsorption and purification unit employs a fixed-bed adsorption column, filled with modified coconut shell activated carbon or coal-based columnar activated carbon, with a particle size of 0.8-1.2 mm, an iodine value of 1200-1400 mg / g, and a specific surface area of ​​[missing information]. The empty bed contact time is 4-8 minutes, and the running empty bed flow rate is 10-18 BV / h.

5. The wastewater treatment method using ceramic ultrafiltration membrane composite oxidation adsorption as described in claim 1, characterized in that, The oxidation reaction unit and the adsorption purification unit are integrated to form a series integrated reaction column. The column consists of a catalytic oxidation zone (0.5-0.8m high) and an adsorption zone (1.2-1.8m high) from bottom to top. The molar ratio of ozone to hydrogen peroxide is 1:0.4-1:0.6, and the total residence time is 20-30min.

6. The wastewater treatment method using ceramic ultrafiltration membrane composite oxidation adsorption as described in claim 1, characterized in that, The ceramic ultrafiltration membrane filtration unit employs a combination of gas-water backwashing and chemically enhanced backwashing, with a backwash gas intensity of 9-11 L / m³. Backwash water intensity 18-22L / The backwashing cycle is 8-20 hours. Chemically enhanced backwashing uses a mixture of 0.6-0.9wt% NaOH and 300-450mg / L NaClO at a temperature of 55-62℃ for 40-50 minutes.

7. A wastewater treatment method using ceramic ultrafiltration membrane composite oxidation adsorption as described in any one of claims 1-6, characterized in that, The system is equipped with sensors for online monitoring of transmembrane pressure difference, ORP, TOC and pH. When the transmembrane pressure difference is ≥0.35MPa or the ORP is lower than the set value, the ozone dosage is automatically increased by 15-20% or the membrane chemical cleaning program is started.

8. A wastewater treatment method using ceramic ultrafiltration membrane composite oxidation adsorption as described in any one of claims 1-6, characterized in that, The concentrate produced by the ceramic ultrafiltration membrane is refluxed to the oxidation reaction unit for cyclic catalytic oxidation, with a circulation rate of 4-7 times. After circulation, the concentrate is then introduced into the subsequent concentration or solidification unit.

9. A wastewater treatment method using ceramic ultrafiltration membrane composite oxidation adsorption as described in any one of claims 1-6, characterized in that, The ceramic ultrafiltration membrane filtration unit operates in a constant flux mode, with the flux controlled between 80-250 L / m³. The transmembrane pressure difference is maintained by adjusting the speed of the inlet pump through frequency conversion.

10. A wastewater treatment method using ceramic ultrafiltration membrane composite oxidation adsorption as described in any one of claims 1-6, characterized in that, The ozone is added through a titanium alloy microporous aeration disc or a Venturi jet injector, with an average bubble diameter ≤800μm and a gas-liquid mass transfer efficiency ≥85%.

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