Anaerobic membrane biological coupling treatment method for salt-containing organic industrial wastewater

Abstract

The present application belongs to the technical field of industrial wastewater treatment, and particularly relates to a salt-containing organic industrial wastewater anaerobic membrane biological coupling treatment method, which comprises the following steps: S1, after the salt-containing organic industrial wastewater is homogenized and uniformly distributed in a regulating tank, the wastewater enters a first-stage gradient acclimation anaerobic membrane biological reactor; S2, effluent from the first-stage reactor enters a second-stage enhanced degradation anaerobic membrane biological reactor; S3, effluent from the second-stage reactor enters a third-stage deep treatment anaerobic membrane biological reactor; S4, biogas generated by the anaerobic membrane biological reactors at all stages is collected; and S5, effluent from the third-stage reactor enters a subsequent treatment unit or is discharged up to the standard. The present application adopts a three-stage series anaerobic membrane biological reactor, the salinity is gradually increased, the microorganisms at all stages gradually adapt to the high-salt environment, and the dominant flora matched with the corresponding salinity is formed. Compared with a single-stage system, the three-stage gradient acclimation makes the upper limit of the salt tolerance of the system increased from 15000 mg / L to 25000 mg / L, and the COD removal rate still remains above 90% under the condition of a salinity of 20000 mg / L.

Description

Technical Field

[0001] This invention belongs to the field of industrial wastewater treatment technology, specifically relating to an anaerobic membrane-biological coupling treatment method for saline organic industrial wastewater. Background Technology

[0002] Saline organic industrial wastewater is widely generated in industries such as petrochemicals, pharmaceuticals, printing and dyeing, food processing, and seawater utilization. It is characterized by high salt content (typically NaCl concentrations of 5000–30000 mg / L), high organic matter concentration, complex composition, and large fluctuations in biodegradability. High-salt environments exert osmotic pressure stress on microorganisms, leading to cell dehydration, reduced enzyme activity, and severe inhibition of anaerobic microbial metabolic activity, resulting in a significant decrease in the efficiency of traditional anaerobic biological treatment.

[0003] Anaerobic membrane bioreactors (AnMBRs) combine anaerobic biological treatment with membrane separation technology, offering advantages such as long sludge retention time, high organic loading, good effluent quality, and small footprint, demonstrating promising application prospects in the treatment of high-concentration organic wastewater. However, existing technologies still suffer from the following significant drawbacks when treating saline organic wastewater: When the NaCl concentration in wastewater exceeds 5000 mg / L, the methanogenic activity of ordinary anaerobic sludge decreases significantly, and the COD removal rate drops sharply from over 95% to below 85%. When the salinity exceeds 15000 mg / L, traditional anaerobic systems are basically unable to operate stably. Although salt tolerance can be improved to some extent through acclimation with halophilic bacteria, the acclimation period is long, the ability to withstand shock loads is poor, and the system is prone to collapse when salinity fluctuates.

[0004] Salt stress induces microorganisms to secrete large amounts of soluble extracellular polymers (EPS) and soluble microbial products (SMPs). These sticky substances deposit on the membrane surface, forming a dense filter cake layer, resulting in an irreversible membrane fouling rate as high as 33%–40%. Simultaneously, inorganic salt crystallization under high-salt conditions also leads to fouling within the membrane pores, further accelerating membrane flux decline. Traditional AnMBR membranes have an operating cycle of only 10–20 days; frequent chemical cleaning not only increases operating costs but also shortens membrane lifespan.

[0005] Existing technologies mostly employ single-stage AnMBRs to treat saline wastewater. If designed for high salinity, the reactor volume is large and the investment is high; if designed for low salinity, it cannot adapt to salinity fluctuations. Although some studies have used two-stage anaerobic processes, there is a lack of salinity gradient control and functional zoning between the two stages, resulting in unreasonable load distribution at each stage and failing to fully utilize the synergistic effect of microorganisms at each stage.

[0006] Industrial wastewater containing salinity often contains recalcitrant organic pollutants. The high salinity further reduces the degradation capacity of microorganisms, resulting in limited removal rates of recalcitrant COD by traditional AnMBRs, making it difficult for effluent to meet standards. Although electrochemical coupling technology can enhance the degradation of organic matter, existing electrochemical AnMBRs mostly use external power sources, resulting in high energy consumption, and the electrodes are easily passivated by salts.

[0007] Current technologies mainly rely on cross-flow filtration, backwashing, and chemical cleaning to control membrane fouling. Cross-flow filtration requires high-power circulation pumps, which account for more than 30% of the total system energy consumption. Chemical cleaning agents are consumed in large quantities and are prone to causing secondary pollution. Although biogas agitation can reduce energy consumption, existing biogas agitation methods have limited shearing effect on the membrane surface, resulting in poor fouling control.

[0008] In summary, existing anaerobic membrane biological treatment technologies for saline organic wastewater suffer from problems such as insufficient salt tolerance, severe membrane fouling, high operating costs, and poor resistance to shock loads. There is an urgent need to develop a highly efficient, stable, and low-energy-consumption coupled treatment method. Summary of the Invention

[0009] The purpose of this invention is to provide an anaerobic membrane-biological coupling treatment method for saline organic industrial wastewater. This method achieves efficient and stable treatment of high-salinity organic wastewater through multiple technologies such as three-level gradient salinity acclimatization, micro-electrolysis catalytic enhancement, immobilized biological carrier, dynamic membrane prefiltration, and biogas internal circulation cross-flow.

[0010] To achieve the above objectives, the present invention provides the following technical solution: a method for anaerobic membrane-biological coupling treatment of saline organic industrial wastewater, comprising the following steps: S1. After being homogenized and equalized in the equalization tank, the saline organic industrial wastewater enters the first-stage gradient acclimation anaerobic membrane bioreactor, where the first-stage anaerobic degradation and membrane separation are carried out under the condition of salinity mass concentration of 3000-8000 mg / L. S2. The effluent from the primary reactor enters the secondary enhanced degradation anaerobic membrane bioreactor. Under the condition of a salinity mass concentration of 8000-15000 mg / L, the second-stage anaerobic degradation and membrane separation are carried out through the synergistic effect of the built-in micro-electrolysis catalytic packing and the composite halophilic bacteria agent. S3. The effluent from the secondary reactor enters the tertiary deep treatment anaerobic membrane bioreactor. Under the condition of a salinity mass concentration of 15000-25000 mg / L, the third-stage deep anaerobic degradation and membrane separation are carried out through the synergistic effect of immobilized biological carriers and dynamic membrane pre-filtration layer. S4. After the biogas produced by each anaerobic membrane bioreactor is collected, part of it is returned to the bottom of the corresponding reactor to form a gas-liquid two-phase cross flow, which turbulently washes the membrane surface. S5. The effluent from the three-stage reactor enters the subsequent treatment unit or is discharged in compliance with standards.

[0011] As a preferred embodiment of the anaerobic membrane-biocoupled treatment method for saline organic industrial wastewater of the present invention, the built-in micro-electrolysis catalytic packing in S2 is an iron-carbon-lanthanide metal oxide composite packing with a particle size of 5-15 mm and a filling volume accounting for 15%-25% of the effective volume of the reactor; the micro-electrolysis catalytic packing is set in the water distribution zone below the membrane module, and the wastewater flows from bottom to top through the packing layer before entering the membrane separation zone.

[0012] As a preferred embodiment of the anaerobic membrane-biological coupling treatment method for saline organic industrial wastewater of the present invention, the composite halophilic bacterial agent is prepared by mixing halophilic methanogens, halophilic acidifying bacteria, and halophilic acetic bacteria in a volume ratio of 2-3:3-4:1-2, and the inoculum amount is 8%-15% of the effective volume of the reactor; the composite halophilic bacterial agent is cultivated using a gradient salinity acclimatization method, with an acclimatization period of 15-25 days, and the final salinity after acclimatization is not less than 25000 mg / L.

[0013] As a preferred embodiment of the anaerobic membrane-biological coupling treatment method for saline organic industrial wastewater of the present invention, the immobilized biological carrier in S3 is a modified polyurethane foam carrier, the surface of which is loaded with a composite coating of nano-titanium dioxide and chitosan, and the carrier dosage is 20% to 35% of the effective volume of the reactor; the dynamic membrane pre-filtration layer is formed in situ by the anaerobic sludge mixture during the cross-flow filtration process on the membrane surface, and the dynamic membrane thickness is controlled at 80 to 200 μm.

[0014] As a preferred embodiment of the anaerobic membrane-biocoupled treatment method for saline organic industrial wastewater of the present invention, in step S4, the biogas recirculation ratio is 1.5 to 3.0 times the influent volume, and the biogas is evenly distributed below the membrane module through perforated gas distribution pipes to form a gas-liquid two-phase flow with an upward flow velocity of 0.08 to 0.15 m / s; an online biogas desulfurization device is installed on the biogas recirculation pipeline, and the hydrogen sulfide content of the biogas after desulfurization is less than 50 ppm.

[0015] As a preferred method for anaerobic membrane biocoupling treatment of saline organic industrial wastewater according to the present invention, each stage of the anaerobic membrane bioreactor is equipped with a salinity adaptive control system. The salinity in the reactor is detected in real time by an online conductivity monitor. When the salinity fluctuation exceeds the set value ±15%, the fresh water dilution pipeline or the concentrated water return pipeline is automatically opened for adjustment. The salinity adjustment response time does not exceed 10 minutes.

[0016] As a preferred method for anaerobic membrane-biological coupling treatment of saline organic industrial wastewater according to the present invention, the hydraulic retention time (HRT) of each reactor decreases progressively: the HRT of the first-stage reactor is 24–36 h, the HRT of the second-stage reactor is 18–24 h, and the HRT of the third-stage reactor is 12–18 h. The sludge retention time of each reactor is controlled within 30–60 days, and the sludge concentration (MLSS) increases progressively, at 8–12 g / L, 12–18 g / L, and 18–25 g / L, respectively.

[0017] As a preferred method for anaerobic membrane-biological coupling treatment of saline organic industrial wastewater according to the present invention, the membrane modules of each reactor stage are all made of polyvinylidene fluoride hollow fiber ultrafiltration membranes with a pore size of 0.05–0.2 μm and a membrane flux of 6–12 L / (m²). 2 •h); The membrane module adopts an intermittent suction operation mode, suctioning for 8 to 12 minutes and stopping for 1 to 3 minutes. Chemical cleaning is performed when the transmembrane pressure difference reaches 25 kPa.

[0018] As a preferred method for anaerobic membrane biocoupling treatment of saline organic industrial wastewater according to the present invention, the preparation method of the iron-carbon-lanthanide metal oxide composite packing is as follows: iron powder, activated carbon powder, lanthanum oxide, and cerium oxide are mixed in a mass ratio of 60-70:20-25:3-5:2-4, a binder is added and granulated, and then sintered at a high temperature of 800-1000℃ for 2-4 hours. After natural cooling, the composite packing is obtained.

[0019] As a preferred method for anaerobic membrane bio-coupling treatment of saline organic industrial wastewater according to the present invention, part of the effluent from the three-stage reactor is recycled to the inlet of the first-stage reactor, with a recycling ratio of 20% to 50%, to dilute the salinity of the influent and replenish the alkalinity; the total COD removal rate of the system is ≥90%, the effluent COD is ≤300mg / L, and the system can withstand an influent salinity shock load of up to 50%.

[0020] Compared with the prior art, the beneficial effects of the present invention are: This invention employs a three-stage anaerobic membrane bioreactor series, with salinity gradually increasing. Microorganisms at each stage progressively adapt to the high-salt environment, forming dominant bacterial communities that match the corresponding salinity. Compared to a single-stage system, the three-stage gradient acclimation increases the system's salt tolerance limit from 15,000 mg / L to 25,000 mg / L, while maintaining a COD removal rate of over 90% even at a salinity of 20,000 mg / L. Each stage has clearly defined functional zones: the first stage focuses on hydrolysis, acidification, and gradient acclimation; the second stage enhances methanogenesis and the degradation of recalcitrant organic matter; and the third stage provides advanced treatment and water quality assurance, achieving efficient enrichment of functional bacteria and maximizing system efficiency.

[0021] This invention utilizes a two-stage reactor with an embedded iron-carbon-lanthanide metal oxide composite packing material. By leveraging the micro-electric field generated by the galvanic cell effect and hydroxyl radicals, it oxidizes and decomposes recalcitrant macromolecular organic matter into easily biodegradable small molecules, thereby improving the biodegradability of wastewater. Simultaneously, the Fe generated by micro-electrolysis... 2+ It can promote electron transport in microorganisms and enhance the metabolic activity of methanogens. Lanthanide metal oxides, as catalysts, can increase the yield of hydroxyl radicals and delay the passivation of iron-carbon packing materials. Compared with traditional AnMBR, the removal rate of recalcitrant COD is increased by 20%–30%.

[0022] This invention utilizes a three-stage reactor to form a dynamic pre-filtration layer on the membrane surface from the sludge mixture. This layer effectively traps most EPS, SMP, and colloidal substances, protecting the ultrafiltration membrane from fouling. Simultaneously, the modified polyurethane foam carrier provides a surface for microbial attachment and growth, reducing the number of free bacteria and lowering the risk of membrane pore blockage. The nano-titanium dioxide-chitosan coating on the carrier surface adsorbs dissolved organic matter and inhibits microbial adhesion to the membrane surface. Compared to traditional AnMBR, the membrane operating cycle is extended by 2–3 times, and the frequency of chemical cleaning is reduced by more than 60%.

[0023] This invention utilizes the system's self-produced biogas as power, which flows back to the area below the membrane module, forming a two-phase upward flow of gas and liquid. The shear force generated by the gas agitation effectively washes away the filter cake layer on the membrane surface. Compared to traditional cross-flow pumps, biogas cross-flow can save 30%–50% of membrane circulation energy consumption. During its ascent, the biogas also acts as a mixer, improving mass transfer conditions and increasing sludge activity. Simultaneously, the thorough contact between biogas and wastewater strips some dissolved methane, improving biogas recovery rate.

[0024] This invention equips each stage of the reactor with an online conductivity monitoring and automatic salinity adjustment system, enabling rapid response to influent salinity fluctuations. Salinity stability within the reactor is maintained through freshwater dilution or effluent recirculation. The salinity adjustment response time is no more than 10 minutes, and the system can withstand salinity shock loads of up to 50%, preventing the collapse of microbial activity due to sudden salinity changes. The three-stage series structure itself also has a buffering effect; the impact of influent salinity fluctuations is significantly reduced after being attenuated by the first two stages.

[0025] This invention utilizes a gradient-acclimated composite halophilic bacterial agent for inoculation, containing halophilic strains with different functions such as hydrolysis and acidification, acetic acid production, and methanogenesis. The resulting bacterial community has a rational structure and complementary functions. Compared to natural acclimation, the system start-up period is shortened from 40–60 days to 15–25 days, and operational stability is significantly improved. The combination of the bacterial agent and the immobilization carrier effectively prevents the loss of functional bacteria, maintaining high biomass and high activity. Attached Figure Description

[0026] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the steps involved in the anaerobic membrane-biological coupling treatment method for saline organic industrial wastewater.

[0027] Figure 2 This is a flow chart of a three-stage anaerobic membrane biocoupled treatment process for saline organic industrial wastewater.

[0028] Figure 3This is a structural diagram of a three-stage advanced anaerobic membrane bioreactor for the coupled anaerobic membrane bioreactor treatment method of saline organic industrial wastewater. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Please see Figure 1-3 The present invention provides the following technical solution: an anaerobic membrane-biological coupling treatment method for saline organic industrial wastewater, comprising the following embodiments: Example 1 A chemical plant generates saline organic wastewater with an influent COD concentration of 8000–12000 mg / L and a NaCl concentration of 8000–12000 mg / L. The treatment capacity is 500 m³ / h. 3 / d. The method of this invention is used for processing, and the specific implementation is as follows: (1) System Configuration One regulating tank with an effective volume of 200 m³ is to be installed. 3 One primary anaerobic membrane bioreactor with an effective volume of 300 m³. 3 One secondary anaerobic membrane bioreactor with an effective volume of 250 m³. 3 One three-stage anaerobic membrane bioreactor with an effective volume of 200 m³. 3 Each reactor stage is equipped with a hollow fiber ultrafiltration membrane module. The membrane material is PVDF, the pore size is 0.1 μm, and the total membrane area per stage is 800 m². 2 Level 2 is 700m 2 Level 3 is 600m 2 .

[0031] The secondary reactor contains an iron-carbon-lanthanide composite packing material with a packing volume of 40 m³. 3 The filler particle size is 8-12mm. The filler composition is: 65% iron powder, 25% activated carbon powder, 5% lanthanum oxide, and 5% cerium oxide, which are sintered at 900℃ for 3 hours.

[0032] Add 50m³ of modified polyurethane foam carrier to the three-stage reactor. 3 The carrier has a size of 10×10×10mm and a surface loaded with a composite coating of nano-TiO2 and chitosan.

[0033] (2) Preparation of compound halophilic bacteria agent Halophilic microorganisms were screened from coastal salt field sediments and sludge from high-salinity wastewater treatment plants. After acclimation to a gradient salinity of 20 days, with a final salinity of 25000 mg / L, halophilic methanogens, halophilic acid-hydrolyzing bacteria, and halophilic acetogenic bacteria were isolated and purified, and then compounded into a composite microbial agent at a volume ratio of 2.5:3.5:1.5. The inoculum size for each reactor stage was 10%.

[0034] (3) Operating parameter control Primary reactor: salinity controlled at 5000–7000 mg / L, HRT approximately 29 h, MLSS approximately 10 g / L, membrane flux 8 L / (m²). 2 •h), aspirate for 10 minutes, then stop for 2 minutes; Secondary reactor: salinity controlled at 10000–12000 mg / L, HRT approximately 24 h, MLSS approximately 15 g / L, membrane flux 9 L / (m²). 2 •h), aspirate for 10 minutes, then stop for 2 minutes; Three-stage reactor: salinity controlled at 12000–14000 mg / L, HRT approximately 19 h, MLSS approximately 22 g / L, membrane flux 10 L / (m²). 2 •h), aspirate for 10 minutes, then stop for 2 minutes; Biogas recirculation ratio: 2.0 times for stage 1, 2.5 times for stage 2, and 2.0 times for stage 3, with a gas velocity of approximately 0.1 m / s.

[0035] The effluent from the third stage is recirculated back to the influent from the first stage, with a recirculation ratio of 30%. (4) Salinity adaptive regulation Each reactor stage is equipped with an online conductivity meter, and the salinity fluctuation threshold is set to ±15%. When the salinity exceeds the upper limit, the desalination valve automatically opens; when the salinity falls below the lower limit, the concentrate return flow rate automatically increases. The adjustment response time is approximately 8 minutes.

[0036] (5) Operational effect After the system stabilized, the average COD of the effluent was 220 mg / L, with a total COD removal rate exceeding 95%; effluent SS was <5 mg / L, and turbidity was <0.5 NTU. The membrane operating cycle was approximately 45 days, and the time for the transmembrane pressure difference to increase from the initial 2 kPa to 25 kPa was 42–48 days. The biogas production rate was approximately 0.45 m³ / s. 3 The COD was approximately 62% per kg of water, with a methane content of about 62%. Even when the influent salinity suddenly increased to 18000 mg / L, the system maintained stable operation, with the COD removal rate decreasing by only 3%–5%, returning to normal after 3 days.

[0037] Example 2 A pharmaceutical company is dealing with saline organic wastewater. The influent COD is 10,000–15,000 mg / L, and the NaCl concentration is 15,000–20,000 mg / L. The treatment capacity is 200 m³ / h.3 / d. Processed using the method of this invention: The salinity of the primary reactor is controlled at approximately 8000 mg / L, with a heating time (HRT) of 36 h; the secondary reactor salinity is controlled at approximately 14000 mg / L, with an HRT of 24 h; and the tertiary reactor salinity is controlled at approximately 18000 mg / L, with an HRT of 18 h. The micro-electrolysis packing material accounts for 20% of the total filler volume, and the carrier dosage is 30%. The inoculum amount of the compound halophilic bacteria agent is 12%.

[0038] Stable operation results: effluent COD ≤ 280 mg / L, total removal rate approximately 92%; membrane operation cycle approximately 35 days; system resistance to salinity shock reaches 50%, and the system did not collapse when the influent salinity rose to 30,000 mg / L in a short period of time.

[0039] The process principle of the invention control method is as follows: 1. The principle of three-level gradient salinity acclimatization Wastewater flows sequentially from low-salinity to high-salinity stages. Microorganisms at each stage experience progressive salt stress, gradually inducing the expression of halophilic genes and synthesizing compatible solutes (such as betaine and tetrahydropyrimidine) to maintain cellular osmotic balance. Each stage develops a dominant microbial community adapted to the corresponding salinity range. Level 1: Salt-tolerant hydrolytic acidifying bacteria dominate, hydrolyzing macromolecular organic matter into volatile fatty acids, while also playing a role in salinity buffering and load regulation; Level 2: Moderately halophilic acetogenic bacteria and methanogenic bacteria dominate, completing the methanation of most organic matter; Level 3: Extremely halophilic archaea dominate, completing the deep degradation of residual organic matter under high-salt conditions.

[0040] The gradual domestication process avoids the mass death of microorganisms caused by the direct impact of high salt, and the functions of each level complement each other, achieving efficient anaerobic degradation in a high-salt environment as a whole.

[0041] 2. Micro-electrolysis catalytic enhancement principle When iron-carbon-lanthanide fillers are immersed in wastewater, they form numerous micro-galvanic cells, with iron as the anode and carbon as the cathode, where electrode reactions occur: Anode: Fe-2e - →Fe 2+ ; Cathode: 2H + +2e - →[H]→H2; New ecological [H] and Fe 2+ It possesses strong reducing properties and can break the chromophores and benzene ring structures of recalcitrant organic compounds. Lanthanide metal oxides (La₂O₃, CeO₂) serve as catalysts, promoting electron transfer on the electrode surface, increasing the efficiency of •OH generation, while simultaneously inhibiting the formation of a passivation layer on the iron surface. The micro-electrolysis product is Fe. 2+It can also serve as a microbial redox medium, promoting extracellular electron transfer and enhancing the metabolic activity of methanogens.

[0042] 3. Dynamic membrane pre-filtration and fouling control principle Under cross-flow filtration conditions, sludge flocs, colloidal particles, and some EPS accumulate on the membrane surface to form a dynamic membrane layer with a certain porosity. This dynamic membrane acts as a "pre-filter." Sieving effect: Retains large organic molecules and colloids, reducing their entry into membrane pores; Adsorption: EPS in the dynamic membrane adsorbs dissolved pollutants; Biodegradation: Microorganisms in the dynamic membrane can degrade some organic matter in situ; Once the dynamic membrane is formed, the main filtration resistance comes from the dynamic membrane layer rather than the membrane itself. The dynamic membrane can be periodically renewed through backwashing or cross-flow flushing to prevent the accumulation of pollutants on the membrane surface and the resulting irreversible fouling.

[0043] 4. Biogas internal circulation cross-flow pollution control principle Biogas is released from the perforated pipe below the membrane module, forming a cluster of bubbles that move upwards, producing the following effects: Shear effect: During the rise of bubbles, shear force is generated on the membrane surface, which peels off the loose filter cake layer; Turbulence effect: Strong turbulence is generated in the gas-liquid two-phase flow, which reduces concentration polarization; Mixing effect: Promotes mud-water mixing within the reactor and improves mass transfer; Biogas cross-flow requires no additional power equipment, utilizing the system's own energy to achieve "waste treatment with waste." The rising biogas is collected and reused after being released at the liquid surface, forming a closed loop.

[0044] 5. Salinity adaptive regulation principle Based on the linear correlation between conductivity and salinity, online conductivity monitoring reflects the salinity level within the reactor in real time. The PLC control system automatically executes adjustment strategies according to set thresholds. High salinity → Open the freshwater dilution valve → Reduce salinity; Low salinity → Increase concentrate reflux or reduce dilution water → Increase salinity; Normal fluctuations → Maintain the status quo; The three-stage series structure forms a natural salinity buffer zone, with influent salinity fluctuations gradually decreasing at each stage, and the final stage exhibiting the highest salinity stability. The combination of adaptive regulation and gradient buffering ensures that the system remains within the optimal salinity range even under salinity fluctuations.

[0045] 6. Mechanism of action of immobilized biological carriers The modified polyurethane foam carrier has a three-dimensional network structure and a large specific surface area, providing a place for microorganisms to attach and grow. Retain microorganisms, prevent the loss of sludge under high salinity, and maintain high biomass; A microenvironmental gradient is formed inside the carrier, and the surface and internal bacterial communities are differentiated and functionally complementary. Nano-TiO2-chitosan coating enhances the hydrophilicity and biocompatibility of the carrier, promoting microbial biofilm formation; The carrier moves with the water flow, generating slight friction on the membrane surface, which helps control membrane fouling.

[0046] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for anaerobic membrane-biological coupling treatment of saline organic industrial wastewater, characterized in that, Includes the following steps: S1. After being homogenized and equalized in the equalization tank, the saline organic industrial wastewater enters the first-stage gradient acclimation anaerobic membrane bioreactor, where the first-stage anaerobic degradation and membrane separation are carried out under the condition of salinity mass concentration of 3000-8000 mg / L. S2. The effluent from the primary reactor enters the secondary enhanced degradation anaerobic membrane bioreactor. Under the condition of a salinity mass concentration of 8000-15000 mg / L, the second-stage anaerobic degradation and membrane separation are carried out through the synergistic effect of the built-in micro-electrolysis catalytic packing and the composite halophilic bacteria agent. S3. The effluent from the secondary reactor enters the tertiary deep treatment anaerobic membrane bioreactor. Under the condition of a salinity mass concentration of 15000-25000 mg / L, the third-stage deep anaerobic degradation and membrane separation are carried out through the synergistic effect of immobilized biological carriers and dynamic membrane pre-filtration layer. S4. After the biogas produced by each anaerobic membrane bioreactor is collected, part of it is returned to the bottom of the corresponding reactor to form a gas-liquid two-phase cross flow, which turbulently washes the membrane surface. S5. The effluent from the three-stage reactor enters the subsequent treatment unit or is discharged in compliance with standards.

2. The anaerobic membrane-biological coupling treatment method for saline organic industrial wastewater according to claim 1, characterized in that: The built-in micro-electrolysis catalytic packing in S2 is an iron-carbon-lanthanide metal oxide composite packing with a particle size of 5-15 mm and a filling volume accounting for 15%-25% of the effective volume of the reactor. The micro-electrolysis catalytic packing is set in the water distribution zone below the membrane module, and the wastewater flows from bottom to top through the packing layer before entering the membrane separation zone.

3. The anaerobic membrane-biological coupling treatment method for saline organic industrial wastewater according to claim 1, characterized in that: The compound halophilic bacterial agent is composed of halophilic methanogens, halophilic acidifying bacteria, and halophilic acetic bacteria in a volume ratio of 2-3:3-4:1-2. The inoculum amount is 8%-15% of the effective volume of the reactor. The compound halophilic bacterial agent is cultivated using a gradient salinity acclimatization method with an acclimatization period of 15-25 days and a final salinity of not less than 25000 mg / L.

4. The anaerobic membrane-biological coupling treatment method for saline organic industrial wastewater according to claim 1, characterized in that: The immobilized biological carrier in S3 is a modified polyurethane foam carrier with a nano-titanium dioxide and chitosan composite coating on its surface. The carrier dosage is 20% to 35% of the effective volume of the reactor. The dynamic membrane pre-filtration layer is formed in situ by the anaerobic sludge mixture during the cross-flow filtration process on the membrane surface, and the dynamic membrane thickness is controlled between 80 and 200 μm.

5. The anaerobic membrane-biological coupling treatment method for saline organic industrial wastewater according to claim 1, characterized in that: In the S4, the biogas recirculation ratio is 1.5 to 3.0 times the influent volume. The biogas is evenly distributed below the membrane module through the perforated gas distribution pipe, forming a gas-liquid two-phase flow with an upward flow velocity of 0.08 to 0.15 m / s. An online biogas desulfurization device is installed on the biogas recirculation pipeline, and the hydrogen sulfide content of the biogas after desulfurization is less than 50 ppm.

6. The anaerobic membrane-biological coupling treatment method for saline organic industrial wastewater according to claim 1, characterized in that: Each anaerobic membrane bioreactor is equipped with a salinity adaptive control system. The salinity in the reactor is monitored in real time by an online conductivity monitor. When the salinity fluctuation exceeds the set value ±15%, the freshwater dilution pipeline or the concentrated water return pipeline is automatically opened for adjustment. The salinity adjustment response time does not exceed 10 minutes.

7. The anaerobic membrane-biological coupling treatment method for saline organic industrial wastewater according to claim 1, characterized in that: The hydraulic retention time (HRT) of each reactor decreased progressively: 24–36 h for the first-stage reactor, 18–24 h for the second-stage reactor, and 12–18 h for the third-stage reactor. The sludge retention time of each reactor was controlled between 30 and 60 days, and the sludge concentration (MLSS) increased progressively: 8–12 g / L, 12–18 g / L, and 18–25 g / L, respectively.

8. The anaerobic membrane-biological coupling treatment method for saline organic industrial wastewater according to claim 1, characterized in that: All reactors at each stage use polyvinylidene fluoride hollow fiber ultrafiltration membranes with pore sizes of 0.05–0.2 μm and membrane fluxes of 6–12 L / (m²). 2 •h); The membrane module adopts an intermittent suction operation mode, suctioning for 8 to 12 minutes and stopping for 1 to 3 minutes. Chemical cleaning is performed when the transmembrane pressure difference reaches 25 kPa.

9. The anaerobic membrane-biological coupling treatment method for saline organic industrial wastewater according to claim 2, characterized in that: The preparation method of the iron-carbon-lanthanide metal oxide composite filler is as follows: iron powder, activated carbon powder, lanthanum oxide and cerium oxide are mixed in a mass ratio of 60-70:20-25:3-5:2-4, a binder is added and granulated, and then sintered at a high temperature of 800-1000℃ for 2-4 hours. After natural cooling, the composite filler is obtained.

10. The anaerobic membrane-biological coupling treatment method for saline organic industrial wastewater according to claim 1, characterized in that: Part of the effluent from the tertiary reactor is recycled to the inlet of the primary reactor at a rate of 20% to 50% to dilute the salinity of the influent and replenish alkalinity. The total COD removal rate of the system is ≥90%, the effluent COD is ≤300mg / L, and the system can withstand an influent salinity shock load of up to 50%.

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