Preparation method and application of material for inhibiting EPS (expandable polystyrene) secretion of sludge and relieving MBR (membrane bioreactor) membrane pollution

Abstract

The invention discloses a preparation method and application of a material for inhibiting sludge EPS secretion and relieving MBR membrane pollution, and belongs to the technical field of material preparation methods, the method is characterized in that Baijiu vinasse is made into biochar, and then the biochar is mixed with sodium alginate and 3, 4-dibromofuran-2 (5H)-ketone to prepare QQ spheres, the process is simple and reasonable, the cost is low, the specific surface area of the spheres is large, and the spheres have high porosity and can be used for preparing the QQ spheres. By adding the QQ balls, the secretion of sludge EPS can be influenced, the contents of main components, namely protein and polysaccharide, are obviously reduced, and the membrane flux higher than that of a blank group and the transmembrane pressure difference lower than that of the blank group are shown in the whole operation period of the reactor, so that the membrane pollution problem in the MBR operation process is relieved to a certain extent, the potential membrane pollution characteristic is weakened, and the quality of the MBR is improved. Therefore, the filtering efficiency of the membrane is improved.

Description

Technical Field

[0001] The present invention relates to a method for preparing a material, in particular to a method for preparing a material for inhibiting the secretion of sludge EPS and alleviating MBR membrane fouling and its application, belonging to the technical field of material preparation methods. Background Art

[0002] Membrane fouling includes internal membrane fouling, external membrane fouling and concentration polarization fouling.

[0003] Internal membrane fouling refers to the fouling caused by the adsorption and retention of colloids and other substances in the MBR membrane pores, resulting in the blockage of the membrane pores.

[0004] External membrane fouling refers to the fouling caused by the accumulation and precipitation of particulate matter, macromolecular substances or colloidal particles on the membrane surface, forming a filter cake layer. In addition, due to the interception of ions and solutes near the membrane-solution interface, and then the accumulation and diffusion, the solute concentration near the interface increases, forming a boundary layer, resulting in an increase in membrane resistance and a decrease in flux, which is called concentration polarization fouling.

[0005] According to the type of pollutants, fouling can be divided into organic, inorganic and biological fouling. Among them, the main cause of membrane fouling is the extracellular polymers secreted by microorganisms and microbial metabolites in biological fouling, which adsorb on the membrane surface and membrane pores.

[0006] So far, physical and chemical methods are still the most commonly used methods to control or eliminate membrane fouling.

[0007] These physical methods such as backwashing and chemical methods such as acid-base treatment and oxidation methods have a certain effect on controlling membrane fouling, but they all have many deficiencies.

[0008] Disadvantages of existing means;

[0009] Physical methods usually can only remove reversible fouling, and some strong mechanical cleaning will cause damage to the membrane. If aeration is used to reduce membrane fouling, the optimal aeration conditions need to be studied. When the aeration intensity is too high, membrane fouling may be aggravated. In addition, frequent chemical cleaning will have an adverse effect on the service life of the membrane, reduce the membrane permeability, and lead to the deterioration of the MBR system, resulting in a decrease in the quality of MBR effluent.

[0010] When using NaClO solution for chemical cleaning of the membrane, it cannot completely remove the biological fouling of the MBR membrane, which may lead to the rapid formation of new biofilms by the remaining microorganisms in subsequent MBR operations.

[0011] In addition, the residual NaClO in the MBR will cause serious biological pyrolysis and subsequently form toxic halogenated aromatic hydrocarbon by-products.

[0012] It poses a huge threat to the water environment. In addition, if chemical fungicides are used for a long time to remove the biological pollution of the membrane, bacteria will gradually form a defense mechanism to reduce the effect of the fungicides. Therefore, a method for preparing a material and its application for inhibiting the secretion of sludge EPS and alleviating MBR membrane pollution are designed to solve the above problems. Summary of the Invention

[0013] The main object of the present invention is to provide a method for preparing a material and its application for inhibiting the secretion of sludge EPS and alleviating MBR membrane pollution.

[0014] The object of the present invention can be achieved by adopting the following technical solutions:

[0015] A method for preparing a material for inhibiting the secretion of sludge EPS and alleviating MBR membrane pollution, comprising the following steps:

[0016] Step 1: Doping biochar with n% Fe 3 O 4 Preparation of a composite modified sample. Disperse 10 g of distiller's grains and n% Fe 3 O 4 in a mixed solution of 15 mL of ethanol and 15 mL of ultrapure water, ultrasonic for 30 min, and then place it in an oven at 100 - 105 °C to dry until it becomes a powder;

[0017] Step 2: Put the mixture into a muffle furnace, heat it at 210 °C for 2 h, naturally cool it to room temperature, repeatedly rinse it with high-purity water, and dry it in an oven at 60 °C for 12 h to finally obtain a composite modified product of distiller's grains and Fe 3 O 4 coupled;

[0018] Step 3: Screen the composite modified product of distiller's grains and Fe 3 O 4 coupled;

[0019] Step 4: Mix water, polyvinyl alcohol, and sodium alginate in a mass ratio of 50:5:1, place the mixed solution in a high-pressure sterilizer at 121 °C for 15 min, and then place it in an oven at 60 °C until the solution is completely dissolved;

[0020] Step 5: Prepare a boric acid calcium chloride solution;

[0021] Step 6: Add biochar and 3,4-dibromofuran-2(5H)-one (its function is to inhibit quorum sensing of microorganisms, thereby inhibiting the secretion of EPS, etc.) to the mixed solution of water, polyvinyl alcohol, and sodium alginate. The addition amount is 0.05 g of biochar and 0.03 g of 3,4-dibromofuran-2(5H)-one per milliliter of the mixed solution. Stir and mix well, load it into a 25 ml syringe, and slowly drip it into the boric acid calcium chloride solution and crosslink for 4 h;

[0022] Step 7: Immerse the primary spheres obtained from the boric acid calcium chloride solution in the sodium sulfate solution for 8 h for further crosslinking and curing, and take out the obtained spheres for standby.

[0023] Preferably, in Step 1, n is Fe 3 O 4 The mass ratio to the distillers' grains, and initially set n to 0, 2, 4, 6, 8, 10;

[0024] Among them, Fe 3 O 4 Is added as an electron acceptor.

[0025] Preferably, the screening in Step 3 includes the following steps:

[0026] S11: First, add 10 mg / L phenol stock solution to the jacketed beaker, and adjust the pH of the system to 7.0 ± 0.2;

[0027] S12: Then add 10 mL of PBS, and then dilute it to 100 mL with ultrapure water so that the concentration of phenol is 10 mg / L;

[0028] S13: After adding 1 g / L biochar doped with n% Fe 3 O 4 Composite material, set the rotation speed of the magnetic stirrer to 500 r / min, and stir for 20 min in the dark to achieve adsorption-desorption equilibrium;

[0029] S14: Turn on the xenon lamp, take 3 ml of water samples at set time intervals, store them in centrifuge tubes after passing through a 0.22 μm filter membrane, and wrap them with tin foil and store them in a 4 °C refrigerator for testing.

[0030] Preferably, in Step 5, boric acid, calcium chloride, and water are mixed at a mass ratio of 7:4:100.

[0031] Application of a material for inhibiting sludge EPS secretion and alleviating MBR membrane pollution, characterized in that it includes the following steps:

[0032] S21: Use an MBR reactor with an effective volume of 12 L, and the device flow rate is controlled by two peristaltic pumps to keep the reactor running stably. The pore size of the hollow fiber membrane used in the experiment is 0.2 μm, and the membrane area is 0.8 m 2 , and use a pressure gauge to monitor the reactor TMP in real time. Among them, no substances are added to the first group of reactors, and quenching agents and biochar spheres are added to the second group of reactors, and the addition amount of the spheres is 5 g / L;

[0033] S22: During the experiment, take a certain amount of sludge samples from three shake flasks every two days, extract their EPS, and measure the protein and polysaccharide contents.

[0034] Advantageous technical effects of the present invention:

[0035] The present invention provides a method for preparing a material for inhibiting sludge EPS secretion and alleviating MBR membrane fouling and its application. The present invention mainly uses distiller's grains as raw materials to produce QQ pellets. Not only is the preparation process simple, the operation convenient, and the production cycle short, but it can also expand the comprehensive utilization of distiller's grains and reduce its environmental pollution. Compared with some complex pretreatment technologies, the pellet production process is relatively simple, easy to operate and control, reduces the technical difficulty and requirements for equipment, and has a significant effect on controlling MBR membrane fouling, effectively improving the stability and treatment efficiency of the sewage treatment system;

[0036] Fe 3 O 4 The addition of nanoparticles can increase the specific surface area of distiller's grains, provide more attachment sites for microorganisms, thereby increasing the contact opportunity of organic matter, and can also accelerate the degradation of complex organic matter in distiller's grains, promoting microbial respiration and electron transfer processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Removal effect diagram of phenol by the biochar-doped Fe 3 O 4 composite sample according to a preferred embodiment of the method for preparing a material for inhibiting sludge EPS secretion and alleviating MBR membrane fouling and its application of the present invention;

[0038] Figure 2 Change diagram of protein and polysaccharide in EPS according to a preferred embodiment of the method for preparing a material for inhibiting sludge EPS secretion and alleviating MBR membrane fouling and its application of the present invention;

[0039] (a) Change diagram of polysaccharide in LB-EPS;

[0040] (b) Change diagram of protein in LB-EPS;

[0041] (c) Change diagram of polysaccharide in TB-EPS;

[0042] (d) Change diagram of protein in TB-EPS;

[0043] Figure 3 Change diagram of protein and polysaccharide in SMP according to a preferred embodiment of the method for preparing a material for inhibiting sludge EPS secretion and alleviating MBR membrane fouling and its application of the present invention;

[0044] (a) Change diagram of polysaccharide in SMP;

[0045] (b) Change diagram of protein in SMP;

[0046] Figure 4 Variation diagrams of the reactor membrane flux (a) and transmembrane pressure difference (b) of a preferred embodiment of the method for preparing a material for inhibiting sludge EPS secretion and alleviating MBR membrane fouling and its application according to the present invention. Detailed implementation manners

[0047] To make the technical solutions of the present invention clearer and more definite to those skilled in the art, the present invention will be further described in detail below in conjunction with embodiments and the accompanying drawings. However, the implementation manners of the present invention are not limited thereto.

[0048] Biochar doped with n% Fe 3 O 4 Preparation of the composite modified sample (n is the mass ratio of Fe 3 O 4 to the mass of distiller's grains. Initially, n is set to 0, 2, 4, 6, 8, 10. Among them, the purpose of adding Fe 3 O 4 is to serve as an electron acceptor to promote the electron transfer between the organic matter in the distiller's grains and microorganisms, and accelerate the degradation process of the organic matter) Disperse 10 g of distiller's grains and n% Fe 3 O 4 in a mixed solution of 15 mL of ethanol and 15 mL of ultrapure water, ultrasonicate for 30 min, and then place it in an oven at 100 - 105 °C to dry to powder.

[0049] (2) Subsequently, put the mixture into a muffle furnace and heat it at 210 °C for 2 h. After naturally cooling to room temperature, rinse it repeatedly with high-purity water and dry it in an oven at 60 °C for 12 h.

[0050] Finally, obtain the composite modified product of the coupling of distiller's grains and Fe 3 O 4

[0051] (3) Screening of the Fe 3 O 4 doped composite modified samples. First, add 10 mg / L phenol stock solution to a jacketed beaker. After adjusting the pH of the system to 7.0 ± 0.2, add 10 mL of PBS, and then dilute it to 100 mL with ultrapure water to make the concentration of phenol 10 mg / L. After adding 1 g / L of biochar doped with n% Fe 3 O 4 composite material, set the rotation speed of the magnetic stirrer to 500 r / min, and stir in the dark for 20 min to reach the adsorption-desorption equilibrium. Then turn on the xenon lamp, take 3 ml of water samples at set time intervals, store them in centrifuge tubes after passing through a 0.22 μm filter membrane, and wrap them with tin foil and store them in a 4 °C refrigerator for testing. Then select that when the mass of Fe 3 O 4 is 2% of the mass of the distiller's grains, the removal effect on the pollutant (phenol) is the best (​Figure 1 )。

[0052] (4) Mix water, polyvinyl alcohol, and sodium alginate in a mass ratio of 50:5:1. Place the mixed solution in an autoclave at 121 °C for 15 min, and then place it in an oven at 60 °C until the solution is completely dissolved;

[0053] (5) Preparation of boric acid calcium chloride solution: Mix boric acid, calcium chloride, and water in a mass ratio of 7:4:100;

[0054] (6) Stir and mix biochar (1 g / 20 ml water, polyvinyl alcohol, sodium alginate mixed solution) and 3,4-dibromofuran-2(5H)-one (its function is to inhibit microbial quorum sensing, thus inhibiting the secretion of EPS, etc.) (0.3 g / 10 ml water, polyvinyl alcohol, sodium alginate mixed solution), load it into a 25 ml syringe, and slowly drip it into the boric acid calcium chloride solution, and crosslink for 4 h;

[0055] (7) Immerse the primary spheres obtained in the boric acid calcium chloride solution in a sodium sulfate solution for 8 h for further crosslinking and curing; take out the obtained spheres for standby.

[0056] (II) Method for verifying the function of the spheres (flask experiment for inhibiting EPS secretion from sludge);

[0057] (1) Conduct a flask experiment by combining the inoculation sludge discharge method and the intermittent aeration method. Take 500 ml of sludge mixture, wash the sludge by centrifugation to remove the supernatant, and resuspend the washed sludge in synthetic sewage with distilled water to maintain a sludge concentration of 5 g / L.

[0058] (2) Add spheres with an initial mass concentration of 5 g / L, and carry out the experiment under the conditions of 25 °C and 180 r / min on a magnetic stirrer. The influent pH is 7 + 0.2, the operation mode is intermittent, there are two cycles in a day, stir for 10 h, the whole cycle is 12 h, use a time switch to control the operation time of each stage, control the drainage ratio to be 50%, and the HRT is 12 h.

[0059] (III) Method for verifying the function of the spheres (membrane fouling control experiment)

[0060] (1) Use an MBR reactor with an effective volume of 12 L, and the flow rate of the device is controlled by two peristaltic pumps to keep the reactor running stably. The pore size of the hollow fiber membrane used in the experiment is 0.2 μm, and the membrane area is 0.8 m 2 , and use a pressure gauge to monitor the TMP of the reactor in real time. Among them, no substances are added to the first group of reactors, and the second group of reactors is added with spheres containing a quenching agent and biochar, and the addition amount of the spheres is 5 g / L.

[0061] (III) Research on the efficacy of the spheres

[0062] During the experiment, a certain amount of sludge samples were taken from three shake flasks every two days, and their EPS was extracted to measure the protein and polysaccharide contents. In this study, the bound EPS was divided into LB-EPS (loose EPS) and TB-EPS (tight EPS). The increase in EPS content will intensify membrane fouling and lead to a decrease in membrane flux.

[0063] As Figure 1 shown, for polysaccharides, the content in TB-EPS is significantly higher than that in LB-EPS. The polysaccharide content in TB-EPS is between 50 - 150 mg / L, while the polysaccharide content in LB-EPS is only 50 - 90 mg / L. For proteins, the content in TB-EPS and LB-EPS has little difference, both being between 5 - 45 mg / L.

[0064] Compared with the blank group, the addition of sodium alginate beads and QQ beads both reduced the EPS content, indicating that the addition of QQ beads inhibited the EPS secretion in the shake flasks, and had a better inhibitory effect on the less mobile TB-EPS adhering to the cell surface, while having a limited inhibitory effect on the loose LB-EPS.

[0065] Judging from the data, at the end of the operation, the polysaccharides in TB-EPS of the QQ bead group decreased by 46.8% and 13.4% respectively compared with the blank and sodium alginate empty bead groups, and the proteins in LB-EPS of the QQ bead group decreased by 19.4% and 7.2% respectively compared with the blank and sodium alginate empty bead groups.

[0066] SMP is closely related to membrane fouling in the MBR system, and its mechanisms include directly blocking membrane pores, forming a gel layer on the membrane surface, and depositing on the membrane surface to form a cake layer, etc. In this experiment, samples were continuously taken every two days to measure the SMP content in the sludge. As Figure 2 shown for the content changes of polysaccharides and proteins in SMP, the polysaccharides and proteins in SMP showed an increasing trend in the three shake flask experiments. Judging from the data, at the end of the operation, the polysaccharides in the QQ bead group decreased by 7.3% and 1.2% respectively compared with the blank and sodium alginate empty bead groups, and the proteins in the QQ bead group decreased by 12.6% and 28.4% respectively compared with the blank and sodium alginate empty bead groups.

[0067] Membrane flux and transmembrane pressure difference are important indicators for measuring membrane bioreactors. As the MBR operation time increases, various pollutants (such as microorganisms, cell debris, extracellular polymers) will gradually accumulate on the membrane surface to form a cake layer, thereby reducing the membrane flux. As Figure 3 shown, they both decreased sharply on the 10th day. The transmembrane pressure difference of the reactor without adding QQ beads reached 32.34 on the 10th day, and membrane fouling had occurred, but the transmembrane pressure difference of the reactor with QQ beads reached 33.6 on the 13th day, indicating that adding QQ beads can effectively alleviate membrane fouling.

[0068] The following conclusions can be drawn from the above:

[0069] (1) At the end of the experiment, the polysaccharide in TB-EPS of the QQ bead group decreased by 46.8% and 13.4% respectively compared with the blank group and the sodium alginate empty bead group, and the protein in LB-EPS decreased by 19.4% and 7.2% respectively compared with the blank group and the sodium alginate empty bead group. The secretion of EPS was effectively reduced.

[0070] (2) In SMP, the QQ bead group showed an obvious effect of inhibiting polysaccharide release. The polysaccharide concentration in its supernatant was much lower than that of the group without beads, indicating that QQ beads may effectively adsorb or degrade polysaccharides in the early stage. As the experiment progressed, the protein in the QQ bead group was steadily released in the later stage, and the total amount of protein released was significantly lower than that of the group without beads as a whole, indicating that the overall release amount of protein can be controlled.

[0071] (3) The QQ bead group reactor showed a higher membrane flux and a lower transmembrane pressure difference than the blank group throughout the operation cycle. This indicates that adding QQ beads alleviated the membrane fouling problem during the operation of MBR to a certain extent, thus improving the membrane filtration efficiency.

[0072] As described above, the above are only further embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the scope disclosed by the present invention, according to the technical solution and concept of the present invention, makes equivalent substitutions or changes, all belong to the protection scope of the present invention.

Claims

1. A method for preparing a material for inhibiting sludge EPS secretion and alleviating MBR membrane pollution, characterized in that: The steps include: Step 1: Preparation of biochar-doped n% Fe3O4 composite modified sample: 10g of wine lees and n% Fe3O4 were dispersed in a mixed solution of 15mL ethanol and 15mL ultrapure water, ultrasonicated for 30min, and then placed in an oven at 100-105℃ to dry into powder; Step 2: Place the mixed powder in a muffle furnace, heat at 210°C for 2 hours, cool naturally to room temperature, repeatedly rinse with high-purity water, and dry in an oven at 60°C for 12 hours to finally obtain a composite modified product of wine lees and Fe3O4 coupling; Step 3: Screening the composite modified product of the coupling of wine lees and Fe3O4; Step 4: Mix water, polyvinyl alcohol and sodium alginate in a mass ratio of 50:5:1, place the mixed solution in a 121°C high pressure sterilizer for 15 minutes, and then place it in a 60°C oven until the solution is completely dissolved; Step 5: preparing calcium borate chloride solution; Step 6: adding biochar and 3,4-dibromofuran-2(5H)-one into a mixed solution of water, polyvinyl alcohol and sodium alginate; The amount of addition is 0.05g of biochar and 0.03g of 3,4-dibromofuran-2(5H)-one per milliliter of mixed solution; Stir and mix well, put into a 25 ml syringe, and drip into the boric acid calcium chloride solution at a uniform rate, and cross-link for 4 hours; Step 7: Soak the primary beads obtained from the boric acid and calcium chloride solution in a sodium sulfate solution for 8 hours for further cross-linking and curing, and take out the obtained beads for later use.

2. The method for preparing a material for inhibiting sludge EPS secretion and alleviating MBR membrane pollution according to claim 1, characterized in that: In step 1, n is Fe a The ratio of O4 to lees mass, n was initially set to 0, 2, 4, 6, 8, 10; Among them, Fe3O4 is added as an electron acceptor.

3. The method for preparing a material for inhibiting sludge EPS secretion and alleviating MBR membrane pollution according to claim 1, characterized in that: The screening in step three includes the following steps: S11: First, add 10 mg / L phenol stock solution into the jacketed beaker to adjust the system pH to 7.0 ± 0.2; S12: Add 10 mL of PBS, and then dilute to 100 mL with ultrapure water to make the concentration of phenol 10 mg / L; S13: After adding 1 g / L biochar doped with n% Fe3O4 composite material, the magnetic stirrer speed was set to 500 r / min and stirred for 20 min in the dark to achieve adsorption-desorption equilibrium; S14: Turn on the xenon lamp and take 3 ml of water sample at set time intervals. After passing through a 0.22 μm filter membrane, store the sample in a centrifuge tube and wrap it in tin foil and store it in a 4°C refrigerator for testing.

4. The method for preparing a material for inhibiting sludge EPS secretion and alleviating MBR membrane pollution according to claim 1, characterized in that: In step five, boric acid, calcium chloride and water are mixed in a mass ratio of 7:4:

100.

5. Application of materials for inhibiting sludge EPS secretion and alleviating MBR membrane pollution, based on the method for preparing materials for inhibiting sludge EPS secretion and alleviating MBR membrane pollution according to claim 1, characterized in that: The steps include: S21: The effective volume of the MBR reactor is 12L. The flow rate of the device is controlled by two peristaltic pumps to keep the reactor running stably. The pore size of the hollow fiber membrane used in the experiment is 0.2μm and the membrane area is 0.8m 2 The TMP of the reactor was monitored in real time using a pressure gauge. The first group of reactors did not add any substances, while the second group of reactors added pellets of quencher and biochar at a pellet addition amount of 5 g / L. S22: During the experiment, a certain amount of sludge samples were taken from three shake flasks every two days, EPS was extracted, and the protein and polysaccharide contents were measured.

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