Core-driven immobilized carrier preparation method and membrane reaction system

Abstract

The present invention discloses a method for preparing a core-driven immobilized carrier and an immobilized microorganism coupled membrane reaction system, which relates to the field of water treatment technology. The system comprises: a membrane bioreactor filled with a core-driven immobilized carrier, wherein a membrane assembly, a pH adjustment system, and an aeration system are installed on the membrane bioreactor. The method for preparing the core-driven microorganism immobilized carrier is as follows: (1) preparing fiber balls to obtain fiber balls A; (2) adsorption and immobilization of microorganisms to obtain fiber balls B adsorbed with a concentrated microalgae-bacteria suspension; (3) preparing a casting solution; (4) assembling immobilized microorganism materials to obtain fiber balls C that have been immobilized and assembled; and (5) restoring microbial activity. The beneficial results of the present invention are: the novel microorganism immobilized carrier has the advantages of high toughness, long service life, large microorganism immobilization capacity, and low mass transfer resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, in particular to a method for preparing a core-driven immobilized carrier and a membrane reaction system. Background Art

[0002] Since the 1980s, membrane bioreactors (MBRs) have attracted attention from countries around the world. After more than 30 years of rapid development, membrane bioreactors have been widely used in the water treatment industry. Their good mud-water separation performance can increase the amount of sludge in the reaction tank and shorten the hydraulic retention time. Compared with the traditional method that requires the setting up of multiple reaction tanks, MBRs have the advantages of small footprint, higher degree of integration, simple operation, and good effluent quality. However, serious membrane pollution greatly increases the operating cost of MBRs, hindering the popularization of MBRs.

[0003] In wastewater treatment, microbial immobilization technology confines suspended sludge within a reactor to a selected carrier. This helps reduce sludge loss with effluent, increases the microbial population within the reactor, shortens reaction time, and mitigates the adverse effects of water quality fluctuations on microorganisms. Selected carriers primarily include adsorbents and embedding materials. Common adsorbent materials include polyurethane foam, coral stone, and fiber bundle composite fillers. However, these materials only immobilize sludge that easily forms biofilms and have limited effectiveness against smaller, suspended sludge with poor biofilm-forming properties. While calcium alginate gel, a common embedding material, is easy to prepare, it suffers from a short lifespan, prone to microbial leakage, and high mass transfer resistance. Therefore, existing carriers used in microbial immobilization technology suffer from short lifespans and prone to microbial leakage. Summary of the Invention

[0004] The object of the present invention is to provide a method for preparing a core-driven immobilized carrier and a reaction system. The present invention has the advantages of long service life and large microbial immobilization capacity.

[0005] The technical solution of the present invention is a method for preparing a core-driven immobilized carrier, comprising the following steps:

[0006] Step 1: Preparation of fiber balls: straightened polylactic acid fiber filaments are extruded to obtain fiber balls with a diameter of 5 to 10 mm. The fiber balls are washed with ethanol, then soaked and washed with pure water, and dried in an oven at 70 to 80° C. to obtain fiber balls A.

[0007] Step 2: Enrichment and fixation of microorganisms: First, the liquid algae species were inoculated into BG11 liquid culture medium and cultured to the logarithmic growth phase under the culture conditions of light intensity of 2500 lux, daily light duration of 24 hours, and an aeration flow rate of 1.0-2.0 L / min to obtain enriched algae species; then, the enriched algae species were inoculated into nitrification sludge to obtain a bacteria-algae mixed system; then, the bacteria-algae mixed system was inoculated into simulated sewage with an aeration flow rate of 1.0-2.0 L / min and cultured until the sludge concentration reached 3000-5000 mg / L, thereby obtaining a bacteria-algae symbiotic system;

[0008] Then, a microalgae-bacteria precipitate is obtained by centrifugation from the bacteria-algae symbiotic system using a centrifuge; the microalgae-bacteria precipitate is then added to actual sewage for re-suspending to obtain a concentrated microalgae-bacteria suspension with a concentration of 20 to 30 g / L; the fiber ball A is placed in the concentrated microalgae-bacteria suspension for 30 minutes, removed and excess liquid is drained to obtain the fiber ball B adsorbed with the concentrated microalgae-bacteria suspension.

[0009] Step 3: Preparation of casting solution: Add polymer and organic polar solvent into a three-necked flask, heat to 60-70° C. in a water bath and stir until they are completely dissolved to form casting solution.

[0010] Step 4: Immerse the fiber ball B in the casting solution for 8 to 12 seconds, then transfer it into the aqueous phase for 3 to 6 seconds to perform a phase inversion reaction to obtain the fiber ball C.

[0011] Step 5: Place fiber ball C in slowly flowing pure water for 30 minutes to allow the phase inversion reaction to proceed completely and to wash away excess organic polar solvent, thereby obtaining fiber ball D.

[0012] Step 6: Pre-cultivate the fiber ball D with simulated urban sewage for 5 days to obtain an immobilized carrier and a finished product; reduce the decrease in microbial activity caused by the immobilization operation and increase the population of microorganisms in the carrier.

[0013] In the aforementioned method for preparing a core-driven immobilized carrier, the liquid algae species in step 2 is Chlorella vulgaris from the Institute of Hydrobiology, Chinese Academy of Sciences; and the nitrified sludge is from the Hangzhou Qige Sewage Treatment Plant.

[0014] In the aforementioned method for preparing a core-driven immobilized carrier, the simulated urban sewage water quality parameters in step 6 are as follows: COD 150-200 mg / L, NH3-N 80-120 mg / L, PO43--P 3-6 mg / L, NaHCO3 0.1 g / L, CaCl2 0.15 g / L, MgSO4·7H2O 0.2 g / L.

[0015] In the aforementioned method for preparing a core-driven immobilized carrier, the organic polar solvent in step three is one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone or dimethyl sulfoxide.

[0016] A membrane reaction system comprises a membrane bioreactor tank, which is filled with an immobilized carrier prepared according to any of the preceding claims; a fixing frame is provided in the membrane bioreactor tank, and a plurality of membrane assemblies are provided on the fixing frame; a water outlet pipe is provided on the bottom surface of the fixing frame, and a suction pump is connected to the water outlet pipe; a vacuum gauge is provided on one side of the suction pump, and a water production regulating valve is provided on the other side; a water production flow meter is provided between the water production regulating valve and the suction pump; an aeration system is connected to the bottom surface of the membrane bioreactor tank, and a pH adjustment system is connected to the top surface of the membrane bioreactor tank.

[0017] In the aforementioned membrane reaction system, the aeration system includes an aeration pipe located in the membrane biological reaction tank, and a plurality of evenly distributed aeration heads are provided on the aeration pipe; the end of the aeration pipe is connected to an air compressor, and a gas flow meter is provided between the air compressor and the aeration pipe, and a gas volume regulating valve is provided on one side of the gas flow meter.

[0018] The pH adjustment system in the aforementioned membrane reaction system includes a pH probe arranged in the membrane bioreactor tank, and a dosing funnel is arranged on one side of the pH probe; a dosing tank is arranged on one side of the membrane bioreactor tank, and a dosing tube that cooperates with the dosing funnel is provided on the dosing tank. The dosing tank is connected to a dosing pump, and a liquid regulating valve is provided on one side of the dosing pump.

[0019] Compared with the existing technology, the present invention uses polylactic acid fiber as the core material of the fiber ball, then adsorbs microorganisms on the fiber ball, and then uses a polymer to construct a 100-200μm thick film on the outside of the fiber ball to form an immobilization carrier with a core drive. Compared with general microbial immobilization materials, the present invention has the advantage of low mass transfer resistance.

[0020] The core material of the present invention is polylactic acid fiber, which serves as an adsorption material to fix microorganisms during the microbial immobilization operation. When the reaction system is stably operating, it can be absorbed by microorganisms as a carbon source or decomposed into inorganic matter, making room for the proliferation of the microbial population in the carrier, thereby increasing the fixed amount and toughness of the microorganisms.

[0021] In the present invention, Chlorella and nitrifying sludge are co-cultured as high-efficiency sludge, and the characteristic of Chlorella to produce oxygen through photosynthesis is utilized to increase the dissolved oxygen concentration in the fiber balls in the carrier core, which is beneficial to maintaining the high activity of the nitrifying sludge.

[0022] In the present invention, a novel microbial immobilization carrier is coupled with a membrane bioreactor. Compared with the suspended sludge-membrane bioreactor, the present invention hinders the leakage of microorganisms into the reactor by adding an immobilization carrier, thereby delaying the formation of biofilm on the surface of the membrane component, reducing the concentration of biomass particles in the sewage that are easy to clog the membrane pores, and thus extending the service life of the membrane component.

[0023] Therefore, the present invention can not only improve the service life, but also has the advantages of large fixed amount of microorganisms, high toughness and low mass transfer resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the structure of the core-driven immobilized microorganism coupled membrane reaction system in an embodiment of the present invention;

[0025] Figure 2 Schematic diagram of the cross-sectional structure of a core-driven microorganism immobilization carrier according to an embodiment of the present invention;

[0026] Figure 3-1 The degradation effects of Examples 1-3 and Comparative Examples 1-3 on COD in municipal sewage in Experimental Example 1 are as follows;

[0027] Figure 3-2 The degradation effects of Examples 1-3 and Comparative Examples 1-3 on ammonia nitrogen in urban domestic sewage in Experimental Example 1 are as follows;

[0028] Figure 3-3 The degradation effects of Examples 1-3 and Comparative Examples 1-3 in Experimental Example 1 on total nitrogen in urban domestic sewage are as follows;

[0029] Figure 3-4 The degradation effects of Examples 1-3 and Comparative Examples 1-3 on total phosphorus in urban domestic sewage in Experimental Example 1 are as follows;

[0030] Figure 4-1 The degradation effects of Examples 1-3 and Comparative Examples 1-3 on COD in slaughterhouse wastewater in Experimental Example 2 are as follows;

[0031] Figure 4-2 The degradation effects of Examples 1-3 and Comparative Examples 1-3 on ammonia nitrogen in slaughterhouse wastewater in Experimental Example 2 are as follows;

[0032] Figure 4-3 The degradation effects of Examples 1-3 and Comparative Examples 1-3 on total phosphorus in slaughterhouse wastewater in Experimental Example 2 are as follows;

[0033] Figure 5 The figure shows the flux changes of membrane modules in different comparative examples / embodiments of the present invention.

[0034] The marks in the accompanying drawings are: 1-1 membrane tank, 1-2 membrane assembly, 1-3 fixing frame, 1-4 vacuum gauge, 1-5 suction pump, 1-6 water production flow meter, 1-7 water production regulating valve, 1-8 aeration head, 1-9 gas flow meter, 1-10 gas volume regulating valve, 1-11 air compressor, 1-12 core-driven microbial immobilization carrier, 1-13 pH probe, 1-14 dosing tank, 1-15 dosing pump, 1-16 liquid regulating valve, 1-17 dosing funnel, 1-18 liquid level controller, 2-1 polylactic acid fiber, 2-2 Chlorella-nitrification sludge, 2-3 polymer film. DETAILED DESCRIPTION

[0035] The present invention will be further described below with reference to the examples, but they are not intended to limit the present invention.

[0036] The present invention will be further described below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto.

[0037] The Chlorella sp. used in the examples of the present application was obtained from the China Culture Collection Center, and the nitrification sludge was obtained from the Hangzhou Qige Sewage Treatment Plant.

[0038] Example 1. A method for preparing a core-driven immobilized carrier, characterized by comprising the following steps:

[0039] Step 1: Preparation of fiber balls

[0040] The straightened polylactic acid fiber filaments were extruded by a machine to obtain fiber balls with a diameter of about 5 mm. The fiber balls were washed with ethanol, then soaked and washed twice with pure water, and dried in an oven at 70°C to constant weight.

[0041] Step 2: Enrichment and adsorption of microorganisms

[0042] Step 2-1: Enrichment and culture of microorganisms

[0043] The liquid algae seed of Chlorella was inoculated into 5 L of BG11 liquid culture medium, with a light intensity of 2500 lux, a daily light duration of 24 h, an aeration flow rate of 1.0 L / min, and cultured to the logarithmic growth phase.

[0044] Nitrifying sludge was inoculated into 5 L of simulated municipal sewage at an aeration rate of 1.5 L / min and cultured to a sludge concentration of 3000-5000 mg / L. The simulated municipal sewage water quality parameters were as follows: COD 150-200 mg / L, NH₃-N 80-120 mg / L, PO₄⁻⁻P 3-6 mg / L, NaHCO₃ 0.1 g / L, CaCl₂ 0.15 g / L, and MgSO₄·7H₂O 0.2 g / L.

[0045] Step 2-2, adsorption and fixation of microorganisms

[0046] The microalgae-bacteria precipitate is then centrifuged from the algae-bacteria symbiotic system using a centrifuge. The microalgae-bacteria precipitate is then added to actual sewage for re-suspending to obtain a concentrated microalgae-bacteria suspension with a concentration of 20 to 30 g / L. The fiber ball A is placed in the concentrated microalgae-bacteria suspension for 30 minutes, removed and excess liquid is drained to obtain a fiber ball B adsorbed with the concentrated microalgae-bacteria suspension. The unused concentrated microalgae-bacteria suspension is stored in a refrigerator at 4°C.

[0047] Step 3: Preparation of casting solution

[0048] N,N-dimethylformamide was used as the solvent and polyvinylidene fluoride was selected as the polymer. The two were placed in a three-necked flask, heated to 70° C. in a water bath and stirred until a uniform casting solution was formed, wherein the concentration of polyvinylidene fluoride was 8-12 wt %.

[0049] Step 4: Assembly of immobilized microbial materials

[0050] The fiber balls, loaded with the concentrated microalgae-bacteria suspension, were immersed in the casting solution for 10 seconds to form a polyvinylidene fluoride film on the fiber balls' surface. The fiber balls were then transferred to the aqueous phase, completing the assembly of the immobilized material. The assembled fiber balls were then placed in a slowly flowing stream of pure water for 30 minutes to allow the phase inversion reaction to complete and to remove excess organic solvent.

[0051] Step 5: Restoration of microbial activity

[0052] The prepared immobilized microbial material was pre-cultured in simulated urban sewage for 5 days to restore the microbial activity that had decreased due to the immobilization operation.

[0053] A membrane reaction system, comprising Figure 1 and 2 As shown, it includes a membrane biological reactor 1-1, which is filled with an immobilized carrier 1-12 prepared according to any of the preceding claims; a fixing frame 1-3 is provided in the membrane biological reactor 1-1, and a plurality of membrane modules 1-2 are provided on the fixing frame 1-3; a water outlet pipe is provided on the bottom surface of the fixing frame 1-3, and a suction pump 1-5 is connected to the water outlet pipe; a vacuum gauge 1-4 is provided on one side of the suction pump 1-5, and a water production regulating valve 1-7 is provided on the other side; a water production flow meter 1-6 is provided between the water production regulating valve 1-7 and the suction pump 1-5; an aeration system is connected to the bottom surface of the membrane biological reactor 1-1, and a pH adjustment system is connected to the top surface of the membrane biological reactor.

[0054] The aeration system includes an aeration pipe located in the membrane biological reactor, and a plurality of evenly distributed aeration heads 1-8 are provided on the aeration pipe; an air compressor 1-11 is connected to the end of the aeration pipe, a gas flow meter 1-9 is provided between the air compressor 1-11 and the aeration pipe, and a gas volume regulating valve 1-10 is provided on one side of the gas flow meter 1-9; the pH adjustment system includes a pH probe 1-13 provided in the membrane biological reactor 1-1, and a dosing funnel 1-17 is provided on one side of the pH probe 1-13; a dosing tank 1-14 is provided on one side of the membrane biological reactor 1-1, and a dosing pipe that cooperates with the dosing funnel 1-17 is provided on the dosing tank 1-14; a dosing pump 1-15 is connected to the dosing tank 1-14, and a liquid regulating valve 1-16 is provided on one side of the dosing pump 1-15.

[0055] Example 2. A method for preparing a core-driven immobilized carrier, characterized by comprising the following steps:

[0056] Step 1: Preparation of fiber balls

[0057] The straightened polylactic acid fiber filaments were extruded by a machine to obtain fiber balls with a diameter of about 8 mm. The fiber balls were washed with ethanol, then soaked and washed twice with pure water, and dried in an oven at 70°C to constant weight.

[0058] Step 2: Adsorption of microorganisms

[0059] Step 2-1: Enrichment culture of microorganisms

[0060] The liquid algae seed of Chlorella was inoculated into 5 L of BG11 liquid culture medium, with a light intensity of 2500 lux, a daily light duration of 24 h, an aeration flow rate of 1.0 L / min, and cultured to the logarithmic growth phase.

[0061] Nitrifying sludge was inoculated into 5 L of simulated municipal sewage at an aeration rate of 1.5 L / min and cultured to a sludge concentration of 3000-5000 mg / L. The simulated municipal sewage water quality parameters were as follows: COD 150-200 mg / L, NH₃-N 80-120 mg / L, PO₄⁻⁻P 3-6 mg / L, NaHCO₃ 0.1 g / L, CaCl₂ 0.15 g / L, and MgSO₄·7H₂O 0.2 g / L.

[0062] Step 2-2: Preparation of concentrated microbial suspension

[0063] The microalgae-bacteria precipitate is then centrifuged from the bacteria-algae symbiotic system using a centrifuge; the microalgae-bacteria precipitate is then added to actual sewage for re-suspending to obtain a concentrated microalgae-bacteria suspension with a concentration of 20 to 30 g / L; the fiber ball A is placed in the concentrated microalgae-bacteria suspension for 30 minutes, removed and excess liquid is drained to obtain a fiber ball B adsorbed with the concentrated microalgae-bacteria suspension; and the unused concentrated microalgae-bacteria suspension is stored in a refrigerator at 4°C.

[0064] Step 3: Preparation of casting solution

[0065] N,N-dimethylformamide was used as the solvent and polyacrylonitrile was selected as the polymer. The two were placed in a three-necked flask, heated to 70° C. in a water bath and stirred until a uniform casting solution was formed, wherein the concentration of polyacrylonitrile was 10 wt %.

[0066] Step 4: Assembly of immobilized microbial materials

[0067] The fiber balls, loaded with the concentrated microalgae-bacteria suspension, were immersed in the casting solution for 10 seconds to form a polyvinylidene fluoride film on the fiber balls' surface. The fiber balls were then transferred to the aqueous phase, completing the assembly of the immobilized material. The assembled fiber balls were then placed in a slowly flowing stream of pure water for 30 minutes to allow the phase inversion reaction to complete and to remove excess organic solvent.

[0068] Step 5: Restoration of microbial activity

[0069] The prepared immobilized microbial material was pre-cultured in simulated urban sewage for 5 days to restore the microbial activity that had decreased due to the immobilization operation.

[0070] A membrane reaction system, comprising Figure 1 and 2 As shown, it includes a membrane biological reactor 1-1, which is filled with an immobilized carrier 1-12 prepared according to any of the preceding claims; a fixing frame 1-3 is provided in the membrane biological reactor 1-1, and a plurality of membrane modules 1-2 are provided on the fixing frame 1-3; a water outlet pipe is provided on the bottom surface of the fixing frame 1-3, and a suction pump 1-5 is connected to the water outlet pipe; a vacuum gauge 1-4 is provided on one side of the suction pump 1-5, and a water production regulating valve 1-7 is provided on the other side; a water production flow meter 1-6 is provided between the water production regulating valve 1-7 and the suction pump 1-5; an aeration system is connected to the bottom surface of the membrane biological reactor 1-1, and a pH adjustment system is connected to the top surface of the membrane biological reactor.

[0071] The aeration system includes an aeration pipe located in the membrane biological reactor, and a plurality of evenly distributed aeration heads 1-8 are provided on the aeration pipe; an air compressor 1-11 is connected to the end of the aeration pipe, a gas flow meter 1-9 is provided between the air compressor 1-11 and the aeration pipe, and a gas volume regulating valve 1-10 is provided on one side of the gas flow meter 1-9; the pH adjustment system includes a pH probe 1-13 provided in the membrane biological reactor 1-1, and a dosing funnel 1-17 is provided on one side of the pH probe 1-13; a dosing tank 1-14 is provided on one side of the membrane biological reactor 1-1, and a dosing pipe that cooperates with the dosing funnel 1-17 is provided on the dosing tank 1-14; a dosing pump 1-15 is connected to the dosing tank 1-14, and a liquid regulating valve 1-16 is provided on one side of the dosing pump 1-15.

[0072] Example 3. A method for preparing a core-driven immobilized carrier, characterized by comprising the following steps:

[0073] Step 1: Preparation of fiber balls

[0074] The straightened polylactic acid fiber filaments were extruded by a machine to obtain fiber balls with a diameter of about 10 mm. The fiber balls were washed with ethanol, then soaked and washed twice with pure water, and dried in an oven at 70°C to constant weight.

[0075] Step 2: Adsorption of microorganisms

[0076] Step 2-1: Enrichment and culture of microorganisms

[0077] The liquid algae seed of Chlorella was inoculated into 5 L of BG11 liquid culture medium, with a light intensity of 2500 lux, a daily light duration of 24 h, an aeration flow rate of 1.0 L / min, and cultured to the logarithmic growth phase.

[0078] Nitrifying sludge was inoculated into 5 L of simulated municipal sewage at an aeration rate of 1.5 L / min and cultured to a sludge concentration of 3000-5000 mg / L. The simulated municipal sewage water quality parameters were as follows: COD 150-200 mg / L, NH₃-N 80-120 mg / L, PO₄⁻⁻P 3-6 mg / L, NaHCO₃ 0.1 g / L, CaCl₂ 0.15 g / L, and MgSO₄·7H₂O 0.2 g / L.

[0079] Step 2-2, preparation of concentrated microbial suspension

[0080] The microalgae-bacteria precipitate is then centrifuged from the bacteria-algae symbiotic system using a centrifuge; the microalgae-bacteria precipitate is then added to actual sewage for re-suspending to obtain a concentrated microalgae-bacteria suspension with a concentration of 20 to 30 g / L; the fiber ball A is placed in the concentrated microalgae-bacteria suspension for 30 minutes, removed and excess liquid is drained to obtain a fiber ball B adsorbed with the concentrated microalgae-bacteria suspension; and the unused concentrated microalgae-bacteria suspension is stored in a refrigerator at 4°C.

[0081] Step 3: Preparation of casting solution

[0082] N,N-dimethylformamide was used as the solvent and polyethersulfone was selected as the polymer. The two were placed in a three-necked flask, heated to 70° C. in a water bath and stirred until a uniform casting solution was formed, wherein the concentration of polyethersulfone was 10 wt %.

[0083] Step 4: Assembly of immobilized microbial materials

[0084] The fiber balls, adsorbed with the concentrated microalgae-bacteria suspension, were immersed in a casting solution for 10 seconds to form a polyvinylidene fluoride film on the fiber ball surface. The fiber balls were then transferred to the aqueous phase to complete the assembly of the immobilized material. The assembled fiber balls were then placed in a slowly flowing stream of pure water for 30 minutes to allow the phase inversion reaction to complete and to remove excess organic solvent. This was the same process as in Example 1.

[0085] Step 5: Restoration of microbial activity

[0086] The prepared immobilized microbial material was pre-cultured in simulated urban sewage for 5 days to restore the microbial activity that had decreased due to the immobilization operation.

[0087] A membrane reaction system, comprising Figure 1 and 2 As shown, it includes a membrane biological reactor 1-1, which is filled with an immobilized carrier 1-12 prepared according to any of the preceding claims; a fixing frame 1-3 is provided in the membrane biological reactor 1-1, and a plurality of membrane modules 1-2 are provided on the fixing frame 1-3; a water outlet pipe is provided on the bottom surface of the fixing frame 1-3, and a suction pump 1-5 is connected to the water outlet pipe; a vacuum gauge 1-4 is provided on one side of the suction pump 1-5, and a water production regulating valve 1-7 is provided on the other side; a water production flow meter 1-6 is provided between the water production regulating valve 1-7 and the suction pump 1-5; an aeration system is connected to the bottom surface of the membrane biological reactor 1-1, and a pH adjustment system is connected to the top surface of the membrane biological reactor.

[0088] The aeration system includes an aeration pipe located in the membrane biological reactor, and a plurality of evenly distributed aeration heads 1-8 are provided on the aeration pipe; an air compressor 1-11 is connected to the end of the aeration pipe, a gas flow meter 1-9 is provided between the air compressor 1-11 and the aeration pipe, and a gas volume regulating valve 1-10 is provided on one side of the gas flow meter 1-9; the pH adjustment system includes a pH probe 1-13 provided in the membrane biological reactor 1-1, and a dosing funnel 1-17 is provided on one side of the pH probe 1-13; a dosing tank 1-14 is provided on one side of the membrane biological reactor 1-1, and a dosing pipe that cooperates with the dosing funnel 1-17 is provided on the dosing tank 1-14; a dosing pump 1-15 is connected to the dosing tank 1-14, and a liquid regulating valve 1-16 is provided on one side of the dosing pump 1-15.

[0089] Comparative Example 1

[0090] On the basis of Examples 1-3, no immobilization material was used to immobilize the microorganisms, and the 1:1 mixed, 20 g / L concentrated suspension of Chlorella and nitrification sludge stored for use in Example 1 was directly used for the experiment.

[0091] Comparative Example 2

[0092] On the basis of Examples 1-3, calcium alginate gel was used to replace the core-driven immobilized microbial material prepared in the present invention. The specific operation steps are as follows:

[0093] Step 1: Prepare sodium alginate solution

[0094] 40 g of sodium alginate was added to 960 g of pure water and magnetically stirred for 40 min at a stirring speed of 100-150 r / min. After stopping stirring, the solution was allowed to stand for 24 hours to fully wet the sodium alginate. The stirrer was restarted and stirred until all the sodium alginate solids were dissolved to prepare a 4% sodium alginate solution.

[0095] Step 2: Prepare calcium chloride solution

[0096] Add 40 g of anhydrous calcium chloride to 960 g of pure water, stir magnetically until the anhydrous calcium chloride solid is completely dissolved, and store in a refrigerator at 4°C to prepare a 4% calcium chloride solution.

[0097] Step 3: Immobilization of microorganisms

[0098] The 20 g / L concentrated suspension of Chlorella-nitrifying sludge stored for standby use in Example 1 was mixed with a 4% sodium alginate solution at a ratio of 2:1 to obtain a mixed solution. The mixed solution was dropwise added to a 4% calcium chloride solution at 4°C to obtain calcium alginate gel balls with a diameter of 2-3 mm and embedded with Chlorella-nitrifying sludge. The gel balls were then immersed in the 4% calcium chloride solution for 24 hours to stabilize their structure.

[0099] Comparative Example 3

[0100] On the basis of Examples 1-3, commercially available lightweight ceramsite (diameter 0.8-1.5 cm) was used to replace the core-driven immobilized microbial material prepared in the present invention. The specific operation steps are as follows:

[0101] Step 1: Cleaning of lightweight ceramsite

[0102] The purchased lightweight ceramsite was washed several times with tap water to remove impurities.

[0103] Step 2: Immobilization of microorganisms

[0104] The aeration plate was connected to an external air compressor via an air pipe and placed at the bottom of the pre-incubator. Light ceramsite was filled to cover the aeration plate. Finally, 20 g / L of the concentrated Chlorella-nitrifying sludge suspension stored for standby in Example 1 was added. The suspension was cultured under light and aeration for 3 days to firmly bind the microorganisms to the lightweight ceramsite, thereby preparing a Chlorella-nitrifying sludge-light ceramsite immobilized material.

[0105] Experimental Example 1: Urban domestic sewage degradation experiment

[0106] Hangzhou Qige Sewage Treatment Plant comparative experiment (10 days), selected Examples 1-3 and Comparative Examples 1-3 six schemes for sewage degradation experiments, divided into 6 membrane bioreactors

[0107] Operating conditions: hydraulic retention time 48 hours, sludge retention time 10 days, daily illumination time 24 hours, light intensity 3500 lux, aeration flow rate 1.5 L / min.

[0108] Table 1 Raw water quality

[0109]

[0110]

[0111] (1) Example 1

[0112] Table 2 Water quality after treatment

[0113] project pH CODmg / L Ammonia nitrogen mg / L Total nitrogen mg / L Total phosphorus mg / L scope 6.6-7.4 15.4-19.4 0.8-1.2 3.2-3.8 0.5-0.9 average value 7.0 17.4 1.0 3.5 0.7

[0114] (2) Example 2

[0115] Table 3 Water quality after treatment

[0116] project pH CODmg / L Ammonia nitrogen mg / L Total nitrogen mg / L Total phosphorus mg / L scope 7.1-8.1 8.4-10.4 1.1-1.5 3.9-4.3 0.7-1.1 average value 7.6 10.4 1.3 4.1 0.9

[0117] (3) Example 3

[0118] Table 4 Water quality after treatment

[0119] project pH CODmg / L Ammonia nitrogen mg / L Total nitrogen mg / L Total phosphorus mg / L scope 6.0-7.6 13.7-17.7 0.72-1.12 4.7-5.1 0.7-0.9 average value 6.8 15.7 0.92 4.9 0.8

[0120] (4) Comparative Example 1 (Suspended Chlorella-Nitrification Sludge)

[0121] Table 5 Water quality after treatment

[0122] project pH CODmg / L Ammonia nitrogen mg / L Total nitrogen mg / L Total phosphorus mg / L scope 6.8-8.0 45.5-55.5 5.0-5.8 7.3-7.9 1.4-2.2 average value 7.4 50.5 5.4 7.6 1.8

[0123] Comparing the present application with suspended Chlorella-nitrifying sludge, the present application's core-driven immobilized material treatment effect is better. The reason for this is that the presence of the immobilized carrier in the application improves the activity of the microorganisms.

[0124] (5) Comparative Example 2 (Calcium alginate gel immobilization of microorganisms)

[0125] Table 6 Water quality after treatment

[0126] project pH CODmg / L Ammonia nitrogen mg / L Total nitrogen mg / L Total phosphorus mg / L scope 6.2-7.2 34.3-42.3 4.2-4.8 6.4-7.2 1.5-1.9 average value 6.7 38.3 4.5 6.8 1.7

[0127] Comparing the present application with calcium alginate gel for immobilizing microorganisms, the present application's core-driven immobilization material treatment effect is better. The reason for this is analyzed to be the result of microorganism leakage caused by the rupture of calcium alginate gel, which shows that calcium alginate gel for immobilizing microorganisms has the disadvantages of short service life and easy to cause microorganism leakage.

[0128] (6) Comparative Example 3 (Lightweight ceramsite fixed microorganisms)

[0129] Table 7 Water quality after treatment

[0130] project pH CODmg / L Ammonia nitrogen mg / L Total nitrogen mg / L Total phosphorus mg / L scope 6.5-7.9 57.6-67.6 5.6-7.6 7.5-10.5 2.0-2.4 average value 7.2 62.6 6.6 9.0 2.2

[0131] Comparing the present application with light ceramsite-immobilized microorganisms, the present application's core-driven immobilized material treatment effect is better. The reasons are analyzed as follows: ① The light ceramsite settles at the bottom of the reactor and fails to fully exchange substances with the sewage; ② The opaque light ceramsite hinders the photosynthesis of Chlorella and is not conducive to the growth of Chlorella; this indicates that light ceramsite-immobilized microorganisms have the disadvantages of being not conducive to algae reproduction, having low substance exchange capacity, and low utilization efficiency.

[0132] Experimental Example 2: Slaughterhouse Wastewater Degradation Experiment

[0133] Qiaosi, Yuhang District, Hangzhou was a slaughterhouse for follow-up experiments (10 days). Six schemes of Examples 1-3 and Comparative Examples 1-3 were selected for wastewater degradation experiments, which were divided into 6 membrane bioreactors.

[0134] Operating conditions: hydraulic retention time 48 hours, sludge retention time 10 days, daily illumination time 24 hours, light intensity 3500 lux, aeration flow rate 1.5 L / min.

[0135] Table 8 Raw water quality

[0136] project pH CODmg / L Ammonia nitrogen mg / L Total phosphorus mg / L scope 6.1-8.0 1400-1600 105-125 10-14 average value 7.05 1500 115 12

[0137] (1) Example 1

[0138] Table 9 Water quality after treatment

[0139] project pH CODmg / L Ammonia nitrogen mg / L Total phosphorus mg / L scope 6.4-7.4 370-470 25.9-31.9 2.7-3.7 average value 6.9 420 28.9 3.2

[0140] (2) Example 2

[0141] Table 10 Water quality after treatment

[0142] project pH CODmg / L Ammonia nitrogen mg / L Total phosphorus mg / L scope 6.9-7.3 400-470 28.1-34.1 3.1-4.1 average value 7.1 435 31.1 3.6

[0143] (3) Example 3

[0144] Table 11 Water quality after treatment

[0145] project pH CODmg / L Ammonia nitrogen mg / L Total phosphorus mg / L scope 7.2-7.6 310-380 23.5-29.5 2.6-3.6 average value 7.4 345 26.5 3.1

[0146] (4) Comparative Example 1 (Suspended Chlorella-Nitrification Sludge)

[0147] Table 12 Water quality after treatment

[0148] project pH CODmg / L Ammonia nitrogen mg / L Total phosphorus mg / L scope 7.3-8.3 600-660 48.8-54.8 5.4-6.4 average value 7.8 630 51.8 5.9

[0149] (5) Comparative Example 2 (Calcium alginate gel immobilization of microorganisms)

[0150] Table 13 Water quality after treatment

[0151] project pH CODmg / L Ammonia nitrogen mg / L Total phosphorus mg / L scope 7.4-7.8 480-540 43-49 4.9-5.9 average value 7.6 510 46 5.4

[0152] (6) Comparative Example 3 (Lightweight ceramsite fixed microorganisms)

[0153] Table 14 Water quality after treatment

[0154] project pH CODmg / L Ammonia nitrogen mg / L Total phosphorus mg / L scope 6.8-7.2 750-810 53.2-57.2 6.5-7.0 average value 7.0 780 55.2 6.5

[0155] From Tables 8 to 14, after the slaughterhouse wastewater was treated, the treatment effects of COD, ammonia nitrogen and total phosphorus using the products of Example 1, Example 2 and Example 3 were significantly better than those of all the control examples.

[0156] The embodiments of this specific implementation method are all preferred embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a core-driven immobilized carrier, characterized in that: The following steps are included: Step 1: Preparation of fiber balls: straightened polylactic acid fiber filaments are extruded to obtain fiber balls with a diameter of 5 to 10 mm. The fiber balls are washed with ethanol, then soaked and washed with pure water, and then dried in an oven at 70 to 80° C. to obtain fiber balls A. Step 2: Enrichment and fixation of microorganisms: First, the liquid algae species were inoculated into BG11 liquid culture medium and cultured to the logarithmic growth phase under the culture conditions of light intensity of 2500 lux, daily light duration of 24 hours, and an aeration flow rate of 1.0-2.0 L / min to obtain enriched algae species; then, the enriched algae species were inoculated into nitrification sludge to obtain a bacteria-algae mixed system; then, the bacteria-algae mixed system was inoculated into simulated sewage with an aeration flow rate of 1.0-2.0 L / min and cultured until the sludge concentration reached 3000-5000 mg / L, thereby obtaining a bacteria-algae symbiotic system; The microalgae-bacteria precipitate was then separated from the algae-bacteria symbiotic system using a centrifuge. The microalgae-bacteria precipitate was then added to actual sewage and resuspended to produce a concentrated microalgae-bacteria suspension with a concentration of 20-30 g / L. Fiber balls A were placed in the concentrated microalgae-bacteria suspension for 30 minutes, removed, and excess liquid was drained to obtain fiber balls B adsorbed with the concentrated microalgae-bacteria suspension. Step 3: Preparation of casting solution: Add the polymer and organic polar solvent into a three-necked flask, heat to 60-70°C in a water bath and stir until they are completely dissolved to form a casting solution; Step 4: Immerse fiber ball B in the casting solution for 8 to 12 seconds, then transfer it into the aqueous phase for 3 to 6 seconds to perform a phase inversion reaction to obtain fiber ball C; Step 5: Place fiber ball C in slowly flowing pure water for 30 minutes to allow the phase inversion reaction to proceed completely and to wash away excess organic polar solvent, thereby obtaining fiber ball D; Step 6: Pre-cultivate the fiber ball D with simulated urban sewage for 5 days to obtain an immobilized carrier and a finished product; reduce the decrease in microbial activity caused by the immobilization operation and increase the population of microorganisms in the carrier.

2. The method for preparing a core-driven immobilized carrier according to claim 1, characterized in that: The liquid algae species in step 2 is Chlorella vulgaris from the Institute of Hydrobiology, Chinese Academy of Sciences; and the nitrification sludge is from the Hangzhou Qige Sewage Treatment Plant.

3. The method for preparing a core-driven immobilized carrier according to claim 1, characterized in that: The water quality parameters of the simulated urban sewage in step 6 are as follows: COD 150-200 mg / L, NH3-N 80-120 mg / L, PO4 3- -P 3-6mg / L, NaHCO3 0.1g / L, CaCl20.15g / L, MgSO4·7H2O 0.2g / L.

4. The method for preparing a core-driven immobilized carrier according to claim 1, wherein: The organic polar solvent in step 3 is one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone or dimethyl sulfoxide.

5. A membrane reaction system, characterized in that: The invention comprises a membrane bioreactor (1-1), wherein the membrane bioreactor (1-1) is filled with an immobilized carrier (1-12) prepared according to the preparation method described in any one of claims 1 to 4; a fixing frame (1-3) is provided in the membrane bioreactor (1-1), and a plurality of membrane assemblies (1-2) are provided on the fixing frame (1-3); a water outlet pipe is connected to the bottom surface of the fixing frame (1-3), and a suction pump (1-5) is connected to the water outlet pipe; a vacuum gauge (1-4) is provided on one side of the suction pump (1-5), and a water production regulating valve (1-7) is provided on the other side; a water production flow meter (1-6) is provided between the water production regulating valve (1-7) and the suction pump (1-5); an aeration system is connected to the bottom surface of the membrane bioreactor (1-1), and a pH regulating system is connected to the top surface of the membrane bioreactor.

6. The membrane reaction system according to claim 5, characterized in that: The aeration system comprises an aeration pipe located in a membrane biological reaction tank, wherein a plurality of evenly distributed aeration heads (1-8) are provided on the aeration pipe; an air compressor (1-11) is connected to the end of the aeration pipe; a gas flow meter (1-9) is provided between the air compressor (1-11) and the aeration pipe; and a gas volume regulating valve (1-10) is provided on one side of the gas flow meter (1-9).

7. The membrane reaction system according to claim 5, characterized in that: The pH adjustment system comprises a pH probe (1-13) arranged in a membrane bioreactor (1-1), a dosing funnel (1-17) being arranged on one side of the pH probe (1-13); a dosing tank (1-14) being arranged on one side of the membrane bioreactor (1-1), a dosing pipe being provided on the dosing tank (1-14) and matching the dosing funnel (1-17), a dosing pump (1-15) being connected to the dosing tank (1-14), and a liquid regulating valve (1-16) being arranged on one side of the dosing pump (1-15).

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