CN115925441B - Magnetized organic modified mullite-based porous filler for enriching high-efficiency denitrifying bacteria - Google Patents
Magnetized organic modified mullite-based porous filler for enriching high-efficiency denitrifying bacteria Download PDFInfo
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Abstract
The invention discloses a magnetized organic modified mullite-based porous filler for enriching high-efficiency denitrifying bacteria, and belongs to the technical field of environmental engineering. The invention prepares the natural sillimanite and purple clay material into mullite-based porous filler by grinding, sieving, calcining, pore-forming and other technologies, and loads Fe on the surface of the filler by magnetization and organic modification technologies 3 O 4 And cetyl trimethylammonium bromide, thereby obtaining a porous filler with magnetism, high hydrophilicity and high biological properties. By using the method, the formation rate of the biological film can be greatly improved, the concentration of nitrogen pollutants in the wastewater is obviously reduced, and the total nitrogen in the effluent of the system can be stably discharged up to the standard.
Description
Technical Field
The invention relates to a magnetized organic modified mullite-based porous filler for enriching high-efficiency denitrifying bacteria, belonging to the technical field of environmental engineering.
Background
In the technical field of biological denitrification, compared with the traditional methodThe biological treatment technology of the nitrification-denitrification mode, high-efficiency denitrification is an economical and concise integrated denitrification process. In anaerobic environment, the efficient denitrifying bacteria take carbonate as carbon source, nitrite in the environment is taken as electron acceptor to react with ammonia nitrogen, and nitrogen is metabolized and converted into a small amount of nitrate nitrogen to generate N 2 . Because the high-efficiency denitrifying bacteria are autotrophic bacteria, the high-efficiency denitrifying process has the advantages of almost no need of adding carbon source, no need of adding alkalinity, no need of aeration and oxygen supply required by the nitration process, and the like. However, the efficient denitrifying bacteria are extremely sensitive to the environment, the activity is easy to influence, meanwhile, the multiplication time of the efficient denitrifying bacteria is long, the growth is slow, the efficient denitrifying system is slow to start and the running stability is poor, and the efficient denitrifying process cannot be further popularized in practical application.
The method for intercepting the high-efficiency denitrifying bacteria and ensuring the biomass thereof is an important measure for rapidly starting the high-efficiency denitrification reaction and maintaining the stable operation of the reaction, the high-efficiency denitrifying bacteria are generally enriched by adopting a biomembrane method, and the filler can enable the high-efficiency denitrifying bacteria to be attached to the surface of the high-efficiency denitrifying bacteria to form a biomembrane, so that the residence time of sludge is prolonged, and the method is favorable for the interception of the sludge and the improvement of the high-efficiency denitrification reaction performance. The common biological carrier in the market at present is mainly made of high polymer materials such as polyethylene, polypropylene, polyester and the like, and the organic high polymer materials have obvious advantages in the aspects of materials, density, mechanical strength and the like. However, long-term practical engineering application finds that the hydrophilicity and biocompatibility of the high molecular biological carriers are often poor and the functional design is lacking, so that the biological mass transfer and microorganism adhesion performance are poor, the biological film is difficult to form and easy to fall off, and the related requirements of sewage treatment are difficult to meet, so that the total nitrogen removal rate of the corresponding biological film process is adversely affected.
Disclosure of Invention
Technical problems:
aiming at the problems of difficult enrichment, slow growth, higher cost of the traditional biological carrier material, poor film forming effect, difficult subsequent recovery and disposal and the like of the high-efficiency denitrifying bacteria. The invention provides a preparation method of a magnetized organically modified mullite-based environment-friendly filler, which is used for strengthening enrichment culture of high-efficiency denitrifying bacteria and enhancing process stability.
The technical scheme is as follows:
the invention prepares the natural sillimanite and purple clay material into mullite-based porous filler by grinding, sieving, calcining, pore-forming and other technologies, and loads Fe on the surface of the filler by magnetization and organic modification technologies 3 O 4 And cetyl trimethylammonium bromide, thereby obtaining a porous filler with magnetism, high hydrophilicity and high biological properties.
The invention provides a preparation method of a magnetized organic modified mullite-based porous filler for enriching high-efficiency denitrifying bacteria, which comprises the following steps:
(1) Pretreatment: grinding natural sillimanite and natural purple clay material into powder, respectively carrying out acid washing treatment, washing to neutrality after finishing, and drying to obtain pretreated sillimanite powder and pretreated purple clay powder correspondingly;
(2) Grinding tea seed cake into powder, then carrying out acid washing treatment, washing to be neutral after finishing, and drying to obtain tea seed cake powder; tea seed meal powder and ZrO 2 Mixing the sol uniformly, and drying to obtain a sol-impregnated tea seed meal powder pore-forming agent (referred to as pore-forming agent for short);
(3) Mixing the pretreated sillimanite powder obtained in the step (1) and the pretreated purple sand powder to obtain premixed powder, then adding the pore-forming agent obtained in the step (2), the polyvinyl alcohol aqueous solution and the CaO mineralizer, and uniformly mixing to obtain a mixture;
(4) Calcining the obtained mixture at 1600 ℃ to obtain mullite-based porous filler;
(5) Dispersing ferric salt and ferrous salt in water, and uniformly mixing to obtain a mixed solution; then adding the mullite-based porous filler obtained in the step (4) into the mixed solution, heating and uniformly mixing, regulating the pH value to be alkaline, and continuing the heating reaction; after the reaction is finished, cooling, collecting a solid material through an externally applied magnetic field, washing and drying to obtain the magnetized mullite-based porous filler;
(6) Adding the obtained magnetized mullite-based porous filler into hexadecyl trimethyl ammonium bromide solution, heating for reaction, carrying out solid-liquid separation by using an external magnetic field after the reaction is finished, and drying to obtain the magnetized organic modified mullite-based porous filler.
In one embodiment of the present invention, in step (2), zrO 2 The mass fraction of the sol is 5-10wt%.
In one embodiment of the present invention, in step (2), the tea seed cake powder is mixed with ZrO 2 The mass ratio of the sol is 1:1-3; specifically, the ratio of the two components is 1:2.
In one embodiment of the present invention, in step (3), the mixing mass ratio of the pretreated sillimanite powder and the pretreated purple sand powder is 6:1.
In one embodiment of the invention, in the step (3), the mass ratio of the pore-forming agent to the premixed powder is 1:5-6. Preferably 1:5.
In one embodiment of the present invention, in step (3), the mass fraction of polyvinyl alcohol in the aqueous solution of polyvinyl alcohol is 1 to 5wt%.
In one embodiment of the invention, in step (3), the mass fraction of the aqueous solution of polyvinyl alcohol relative to the total mass of the pore-forming agent and the pre-mixed powder is 1-5%. And particularly, the selection ratio is 2-4%.
In one embodiment of the invention, in the step (3), the mass fraction of CaO relative to the total mass of the pore-forming agent and the premixed flour is 1-5%. Specifically, 1-2% is selected.
In one embodiment of the invention, in step (4), the calcination time is 3 to 5 hours; specifically, the time is optionally 4 hours.
In one embodiment of the invention, in step (5), the ferric salt is a water-soluble ferric salt. In particular, feCl is selected 3 ·6H 2 O。
In one embodiment of the present invention, in step (5), the ferrous salt is a water-soluble ferrous salt. In particular, feSO 4 ·7H 2 O。
In one embodiment of the present invention, in step (5), fe in the trivalent iron salt and the divalent iron salt 3+ With Fe 2+ The molar ratio of (2) to (1).
In one embodiment of the present invention, in the step (5), the mullite-based porous filler is added in an amount of 8 to 10mg/mL relative to the mixed solution. Specifically, 10mg/mL is selected.
In one embodiment of the invention, in the step (5), the mullite-based porous filler is added into the mixed solution, and the temperature for heating and uniformly mixing is 40-60 ℃.
In one embodiment of the invention, in the step (5), the pH is adjusted to be alkaline, and the pH ranges from 12 to 13 in the process of continuously heating the reaction; the heating temperature is 80-90 ℃.
In one embodiment of the present invention, in step (6), the concentration of cetyltrimethylammonium bromide in water is 30mmol/L.
In one embodiment of the invention, in step (6), the molar ratio of magnetized mullite-based porous filler to cetyltrimethylammonium bromide is 1g:1.5mmol.
In one embodiment of the present invention, the preparation method specifically includes the following steps:
(1) Pretreatment: grinding natural sillimanite and natural purple clay material into powder, then carrying out acid washing treatment, washing to neutrality after finishing, and drying to obtain pretreated sillimanite and purple clay powder;
(2) Grinding natural organic waste tea cake into powder, pickling, washing to neutrality, drying, mixing with 5wt% ZrO 2 The sol is uniformly mixed according to the mass ratio of 1:2, and the sol is dried to prepare the sol impregnated tea meal powder pore-forming agent;
(3) Preparing sillimanite and purple clay powder into premixed powder according to the mass ratio of 6:1, and then adding a pore-forming agent according to the ratio of m (premixed powder): m (pore-forming agent) =5:1 to obtain a mixture A; continuously adding 2% of the mixture A by mass of a polyvinyl alcohol aqueous solution (the polyvinyl alcohol concentration is 1 wt%) and 1% of the mixture A by mass of a CaO mineralizer into the mixture A, and uniformly mixing to obtain a mixture B;
(4) Calcining the mixture B obtained in the step (3) at 1600 ℃ for 4 hours to obtain mullite-based porous filler;
(5) 4mol/L FeCl 3 ·6H 2 O solution and 2mol/L FeSO 4 ·7H 2 Mixing 250mL of O solution to generate Fe 3 O 4 Adding 5g of mullite porous material into the mixed solutionHeating in 60 ℃ water bath in an oscillating way, adjusting the pH value of the solution to 12 by using 2mol/L NaOH solution, and then increasing the temperature of the water bath to 80 ℃ and heating in an oscillating way for 1h to obtain a mixed solution; then cooling to room temperature, collecting solid materials through an externally applied magnetic field, washing with deionized water for 3 times, and drying at 80 ℃ for 4 hours to obtain magnetized mullite-based porous filler;
(6) 5g of magnetized mullite-based porous filler is put into 250mL of cetyltrimethylammonium bromide solution with the concentration of 30mmol/L, stirred in a water bath at 80 ℃ for 4h, solid-liquid separation is carried out by using an external magnetic field, and the solid material is dried at 80 ℃ for 4h, thus obtaining the magnetized organic modified mullite-based porous filler.
The invention provides a magnetized organic modified mullite-based porous filler based on the preparation method.
The invention also provides application of the magnetized organic modified mullite-based porous filler in enrichment of high-efficiency denitrifying bacteria.
The invention also provides application of the magnetized organic modified mullite-based porous filler in sewage treatment.
In one embodiment of the invention, magnetized organic modified mullite-based porous filler is used for enriching high-efficiency denitrifying bacteria, 150mL of high ammonia nitrogen (80 mg/L) and nitrite nitrogen (100 mg/L) are added for water distribution, and the biological film forming rate is high, the biomass is high, and the ammonia nitrogen, the nitrite nitrogen and the total nitrogen removal rate are all over 99.9 percent.
The beneficial effects are that:
the invention relates to preparation of a magnetized organic modified mullite-based porous filler for enriching high-efficiency denitrifying bacteria, and the obtained porous filler has good microbial affinity and is applied to enriching the high-efficiency denitrifying bacteria, belonging to the technical field of environmental engineering. The invention prepares the natural sillimanite and purple clay material into mullite-based porous filler by grinding, sieving, calcining, pore-forming and other technologies, and loads Fe on the surface of the filler by magnetization and organic modification technologies 3 O 4 And cetyl trimethylammonium bromide, thereby obtaining a porous filler with magnetism, high hydrophilicity and high biological properties. By using the method, the formation rate of the biological film can be greatly improved, the concentration of nitrogen pollutants in the wastewater can be obviously reduced, and the systemThe total nitrogen in the effluent can be stably discharged up to the standard.
The magnetized organic modified mullite-based porous filler provided by the invention can be used as a microbial carrier, can effectively enrich high-efficiency denitrifying bacteria in a short time, has a good treatment effect on high ammonia nitrogen wastewater, and has total nitrogen, ammonia nitrogen and nitrite nitrogen removal rates of over 99.9 percent.
Drawings
FIG. 1 shows the effect of a conventional polyethylene filler enriched in highly effective denitrifying bacteria on removal of nitrogen-based contaminants
FIG. 2 shows the effect of conventional polypropylene filler enriched in highly effective denitrifying bacteria on removal of nitrogen-based contaminants
FIG. 3 shows the effect of the novel mullite-based porous filler enriched in highly effective denitrifying bacteria on the removal of nitrogen-based contaminants
Detailed Description
The natural sillimanite related to the invention can be purchased from Shijiu Techeng new material science and technology limited company. The natural purple sand related by the invention can be purchased from Yixing purple sand city in China. The tea seed cake related by the invention is oil tea seed cake and can be purchased from Qingshun industry Co.Ltd.
Example 1: screening and drying of natural sillimanite, purple sand material and tea dreg material
Cutting natural sillimanite, purple sand material and tea dreg into small blocks with the length of 1-2 cm, washing the small blocks with deionized water for several times respectively, and drying the small blocks in an oven at 80 ℃ for 4 hours. The dried sillimanite, purple sand and tea dreg materials are respectively ground into powder, the sillimanite and the purple sand are screened by a 200-mesh screen, and the tea dreg powder is screened by a 50-mesh screen. The screened sillimanite and purple clay powder are washed by 5wt% of acetic acid solution, the tea dreg powder is washed by 10wt% of hydrochloric acid solution to remove impurities, and three suspensions are repeatedly washed by deionized water until the pH is neutral. Filtering out the water of the suspension by a suction filtration device, and placing sillimanite, purple sand and tea dreg powder trapped on a filter membrane in an oven at 80 ℃ for drying for 10 hours to obtain dried sillimanite, purple sand and tea dreg powder for later use.
Example 2: preparation of mullite-based porous filler
10g of the tea seed cake powder obtained in example 1 were weighed accurately and placed in 20g of ZrO 2 And (3) in the sol (5 wt%) continuously stirring to uniformly mix them, and drying them in a 110 deg.C oven for 4 hr so as to obtain the invented sol-impregnated tea cake powder pore-forming agent. Dispersing polyvinyl alcohol in water, and uniformly mixing to obtain a mixture with the polyvinyl alcohol content of 1wt%, namely the polyvinyl alcohol binder.
30g of sillimanite and 5g of purple clay material obtained in example 1 are respectively weighed and uniformly mixed to prepare 35g of premixed powder, 7g of pore-forming agent, 4.2g of CaO mineralizer and 8.4g of polyvinyl alcohol binder are sequentially added, and the mixture is uniformly stirred and mixed. Calcining the mixture in a silicon-molybdenum rod electric furnace at 1600 ℃ for 4 hours to prepare the mullite-based porous material. And (3) repeatedly washing the material with deionized water to remove surface impurities after the material is cooled, and drying the material in an oven at 80 ℃ for 10 hours to obtain the mullite-based porous filler. The particle size of the individual filler particles was about 6.2mm and the mass was about 50.22mg.
Example 3: magnetization and organic modification of mullite porous filler
Preparing FeCl of 4mol/L respectively 3 ·6H 2 O solution and 2mol/L FeSO 4 ·7H 2 O solution is prepared into 500mL mixed solution according to the volume ratio of 1:1. 5g of the mullite-based porous filler obtained in example 2 was weighed and put into the mixed solution, and stirred for 1 hour under a water bath condition of 60℃at a stirring speed of 200rpm. And regulating the pH value of the mixed solution to 12 by using 2mol/L NaOH solution, increasing the water bath temperature to 80 ℃, and heating and stirring for 1h. And after stirring, naturally cooling the mixed solution to room temperature, collecting solid filler by an external magnetic field, repeatedly washing with deionized water, and drying at 80 ℃ for 4 hours to obtain the magnetized mullite-based porous material.
Weighing 5g of magnetized mullite-based porous filler, putting the magnetized mullite-based porous filler into 250mL of cetyltrimethylammonium bromide solution with the concentration of 30mmol/L, uniformly mixing, stirring for 4 hours (200 rpm) under the water bath condition of 80 ℃, recovering the solid filler by an external magnetic field after cooling, repeatedly washing with deionized water, and drying for 4 hours under the condition of 80 ℃ to obtain the magnetized organic modified mullite porous filler.
Example 4: enrichment effect of magnetized organic modified mullite porous filler on efficient denitrifying bacteria
The magnetized organically modified mullite porous filler obtained in example 3 was used for enrichment of highly efficient denitrifying bacteria to investigate the adhesion properties of microorganisms. Biofilm attachment experiments were performed in conical flasks with a selected volume of 250mL. 50mL of high-efficiency denitrifying bacteria are placed in a conical flask (the concentration of sludge in a reaction system is kept at 2500 mg/L), porous filler with the volume of about 1/4-1/3 of the conical flask is added, about 150mL of sewage is added, the concentrations of ammonia nitrogen and nitrite nitrogen in the sewage are respectively 80 and 100mg/L, the conical flask is fixed on a constant-temperature shaking table, and the shaking table is set to be at 35 ℃ and starts to operate after the rotating speed is 150 rpm. The reaction system runs for five days, the surface of the porous filler can quickly form a biological film, and the reaction system has good nitrogen pollutant removal effect: the nitrite nitrogen concentration drops to about 6mg/L after one day of operation and to near zero on the next day, while the ammonia nitrogen concentration drops to a lower level on the first day of operation. And the removal rate of ammonia nitrogen, nitrite nitrogen and total nitrogen in the system reaches 99.9% in the fifth day of operation, so that the effluent is ensured to reach the standard for emission. Therefore, the magnetized organic modified mullite porous filler prepared by the method has good efficient denitrifying bacteria enrichment effect.
Comparative example 1: selection of mullite-based porous filler pore-forming agent materials
The preparation method of the porous mullite material mainly comprises a foam method, a gas generation method, a combustible material burning loss method, a template method and the like. The combustible material burning loss method is to mix a great amount of pore forming agent (such as polystyrene granule, saw dust, anthracite, coke, etc.) while compounding, and the pore forming agent occupies certain space in the blank, and after being burnt, the pore forming agent leaves the original position of the matrix to leave pores, thus obtaining the porous material. The combustible material burning loss method can control the micropore structure of the product more conveniently, and is commonly used for preparing porous materials with high porosity and complex shape. The pore-forming agent material of the lost-burning method has the characteristics of no biological toxicity, no secondary pollution, easy acquisition, low cost and the like.
Exploring and comparing pore-forming agents: three pore-forming materials (the other conditions are the same as those in example 2) such as polystyrene particles, walnut shell powder and tea seed cake powder were respectively selected, mullite-based porous fillers were respectively prepared, and the performances thereof were compared as shown in table 1. Tea dreg powder and walnut shell powder as pore-formingThe density of the porous filler prepared by the agent material is 0.57 and 0.61g cm -3 The apparent porosity of the filler prepared by the tea seed meal powder is lower than that of the other two materials, which means that the internal structure of the filler is more compact; the normal temperature compressive strength is higher than that of the other two fillers, which means that the fillers have higher mechanical strength. Meanwhile, the tea seed cake powder is taken as agricultural waste, is simple to obtain and low in price, and is a green material, so that the tea seed cake powder is selected as a pore-forming agent raw material.
TABLE 1 comparison of the Properties of porous fillers prepared from different pore formers
Comparative example 2: influence of the amount of pore-forming agent
Referring to example 2, the amount of pore-forming agent was varied and the mass ratio of pore-forming agent to premixed powder was adjusted to prepare a corresponding mullite-based porous filler, and the results are shown in table 2. When the mass ratio of the pore-forming agent to the premixed powder is 1:4, the volume density and the apparent porosity of the pore-forming agent are respectively 0.42g/cm 3 And 83.3%, which results in a porous filler having a low mechanical strength and a normal temperature compressive strength of only 4.71MPa. When the mass ratio of the pore-forming agent to the premixed powder is 1:6, the normal-temperature compressive strength is higher than that of the other two groups, but the apparent porosity is lower, and when the mass ratio of the pore-forming agent to the premixed powder is 1:7, the apparent porosity of the prepared filler is greatly reduced to 71.5%, so that the subsequent magnetization and organic modification are not facilitated, and meanwhile, the difficulty of adsorption growth of high-efficiency denitrifying bacteria on the surface of the filler is increased. When the mass ratio of the pore-forming agent to the premixed powder is 1:5, the prepared porous filler not only can ensure certain mechanical strength, but also is beneficial to reducing the difficulty of subsequent magnetization and modification, and the mass ratio of the pore-forming agent to the premixed powder is set to be 1:5 in comprehensive ratio selection.
TABLE 2 comparison of the Properties of porous fillers prepared from different pore-formers to Pre-mix powders by mass ratio
Comparative example 3: selection of mullite-based porous filler binder materials
Because the filler is applied to enrichment of high-efficiency denitrifying bacteria, the ideal filler-binder material has the characteristics of no toxicity, aeration resistance, good mass transfer performance, easy preparation, low cost and the like. Aiming at the characteristics, five materials such as agar, sodium alginate, carrageenan, polyacrylamide and polyvinyl alcohol are respectively selected, and the performances of the five materials are studied. As shown in table 3, the agar material was inferior in compression strength and aeration resistance; although the sodium alginate and the carrageenan have no biological toxicity, the sodium alginate is easy to be biodegraded, and the cost of the carrageenan is higher; the polyacrylamide not only has microbial toxicity, but also has higher cost; the polyvinyl alcohol material is used as an organic matter glue, has higher compression strength and aeration resistance strength, and is not easy to be biodegraded. Meanwhile, the cost of the polyvinyl alcohol is low, so that the mullite porous filler bonding agent selects a polyvinyl alcohol solution.
TABLE 3 comparison of the Properties of the immobilized cell support materials
Comparative example 4: condition optimization for mullite-based porous filler preparation
To explore the optimal preparation conditions of the mullite porous filler, a one-factor control test was performed on the calcination temperature, and the test results are shown in table 4. As is clear from table 4, as the calcination temperature increases, the bulk density of the filler gradually decreases and then increases, and the apparent porosity gradually decreases, because the mullite formation causes the volume of the filler to expand and the sintering effect causes the filler to be more densified, so that when the influence of the mullite formation is greater, the density of the filler becomes smaller due to the volume expansion and when the influence of the sintering effect is greater, the density of the filler increases due to the sintering densification, and the denser the filler internal structure becomes, and the apparent porosity becomes smaller. With the increase of the calcination temperature, the compressive strength of the filler begins to change less, and when the calcination temperature is less than 1500 ℃, the volume of the filler is expanded under the influence of mullite, so that the density of the filler is reduced, and the compressive strength of the filler is further reduced, so that the mechanical strength of the filler is reduced, and the utilization of the filler in actual engineering is not facilitated. When the calcining temperature is higher than 1500 ℃, the shrinkage of the filler is increased, the compressive strength of the filler is gradually increased, and the shrinkage influence caused by sintering is larger at the moment, so that the filler is more compact. When the sintering temperature reaches 1600 ℃, the prepared filler shows the best comprehensive performance, the apparent porosity is higher and is 80.3 percent, and the shrinkage phenomenon occurs because the filler is greatly influenced by sintering at the moment, so that the normal-temperature compressive strength of the filler is increased to 5.46Mpa, which indicates that the filler has higher mechanical strength. And when the calcination temperature is continuously increased to 1650 ℃, the filler is excessively contracted due to larger influence of sintering, and the normal-temperature compressive strength of the filler is improved to a certain extent compared with that of 1600 ℃, but the apparent porosity of the filler is greatly reduced, so that the filler is not beneficial to the subsequent magnetization and modification steps. In summary, when the calcination temperature is 1600 ℃, the filler has the most suitable compressive strength and densification degree, and the comprehensive performance is the best.
Table 4 comparison of the properties of porous fillers prepared at different calcination temperatures
Comparative example 5: selection of mullite-based porous filler organic modification agent
The purpose of the organic modification of the filler is to enhance the hydrophilicity and the hydrophilcity of the filler, thereby enhancing the enrichment efficiency of the high-efficiency denitrifying bacteria. Based on the method, three organic matters such as chitosan, octadecyl trimethyl ammonium bromide and hexadecyl trimethyl ammonium bromide are selected to respectively modify the porous filler, the high-efficiency denitrifying bacteria enrichment effect and the denitrification performance of the porous filler are compared, the biomembrane adhesion experiment is carried out in a conical flask, and the volume of the conical flask is 250mL. 50mL of high-efficiency denitrifying bacteria are placed in a conical flask (the concentration of sludge in a reaction system is kept at 2500 mg/L), then a filler with the volume of about 1/4-1/3 of the conical flask is added, about 150mL of sewage is added, the concentration of ammonia nitrogen and nitrite nitrogen in the sewage are respectively 80 and 100mg/L, the conical flask is fixed on a constant-temperature shaking table, a shaking table is set to be 35 ℃ and the operation is started after the rotating speed is 150rpm, and the concentration of ammonia nitrogen, nitrite nitrogen and nitrate nitrogen in daily effluent is detected, wherein the result is shown in a table 5. The porous filler is modified by three organic matters and then subjected to biological film formation for five days, and the removal degree and the removal rate of nitrogen substances are different. The ammonia nitrogen removal rate of the chitosan modified filler is relatively slow, 5.377mg/L ammonia nitrogen still exists in the reaction system in the fifth day of operation, and the total nitrogen removal rate in the fifth day is 97.0%; after being modified by octadecyl trimethyl ammonium bromide, compared with chitosan modification, the nitrogen substance removal effect and the degree bacteria are improved, and the total nitrogen removal rate in the fifth day is improved to 99.3%; the modification effect of the hexadecyl trimethyl ammonium bromide is optimal, the ammonia nitrogen and nitrite nitrogen in the reaction system are reduced to 1.332 and 6.781mg/L after one day of operation, the ammonia nitrogen and nitrite nitrogen residues basically do not exist in the reaction system in the fifth day, the removal rate is over 99.9 percent, and the excellent high-efficiency denitrifying bacteria enrichment effect and denitrification performance are shown, so that the hexadecyl trimethyl ammonium bromide is selected as an organic modification agent.
TABLE 5 Effect of different organic modified Filler enrichment high efficiency denitrifying bacteria on removal of Nitrogen species
And (2) injection: "≡0" indicates that the measurement is negative and the concentration is below the detection limit, near zero.
Comparative example 6: novel porous filler in comparison with conventional filler
In order to examine the superiority of the magnetization organic modified mullite-based porous filler to the enrichment effect of high-efficiency denitrifying bacteria, three groups of tests of a traditional polyethylene filler, a traditional polypropylene filler and a novel porous filler are respectively arranged. Biofilm attachment experiments were performed in conical flasks with a selected volume of 250mL. 50mL of high-efficiency denitrifying bacteria are placed in a conical flask (the concentration of sludge in a reaction system is kept at 2500 mg/L), then a filler with the volume of about 1/4-1/3 of the conical flask is added, about 150mL of sewage is added, the concentration of ammonia nitrogen and nitrite nitrogen in the sewage are respectively 80 and 100mg/L, the conical flask is fixed on a constant-temperature shaking table, a shaking table is set to be 35 ℃ and the running is started after the rotating speed is 150rpm, and the concentration of ammonia nitrogen, nitrite nitrogen and nitrate nitrogen in daily effluent is detected, and the result is shown in a table 6. The nitrite nitrogen concentration is rapidly reduced after the reaction system starts to run, the novel porous filler group is reduced to 6.781mg/L after the first day, each group is reduced to below 1mg/L after the second day of running, the nitrite nitrogen concentration of all experimental groups is reduced to approximately 0 on the fourth day, and the nitrite nitrogen removal rate of each group of fillers is higher than 99.9% on the fifth day. The ammonia nitrogen concentration change trend of each group is similar to that of nitrite nitrogen, the ammonia nitrogen concentration of the other two groups is reduced to 20mg/L after the first day of operation except the novel porous filler, the ammonia nitrogen concentration of the novel porous filler is reduced to 1.332mg/L, and the ammonia nitrogen concentration of each group is reduced to nearly 0mg/L on the fifth day. The data show that the removal effect of each group on ammonia nitrogen and nitrite nitrogen is good, wherein the removal effect and the removal rate of the novel porous filler group are optimal. Although the three experimental groups have good effect of removing ammonia nitrogen and nitrite nitrogen, the change trend of the nitrate nitrogen concentration of each group is different. Since nitrate nitrogen is not formulated in the feed water, its feed water nitrate nitrogen concentration is near zero, whereas during five days of operation the nitrate nitrogen concentration of the conventional polyethylene and polypropylene filler groups increases dramatically, exceeding 150mg/L on the fifth day, which also results in total nitrogen removal rates of the two groups of only 13.1% and 13.4%. In contrast, the concentration of nitrate nitrogen in the spherical filler group is improved, but the improvement degree is lower, and the concentration is reduced from the second day to 1.351mg/L, the total nitrogen removal rate in the fifth day is over 99.9 percent and is far higher than that of the other two groups, so that the filler shows good enrichment effect on high-efficiency denitrifying bacteria.
TABLE 6 Nitrogen removal effect (mg/L) of different filler enriched high efficiency denitrifying bacteria
Claims (9)
1. The preparation method of the magnetized organic modified mullite-based porous filler for enriching the high-efficiency denitrifying bacteria is characterized by comprising the following steps of:
(1) Pretreatment: grinding natural sillimanite and natural purple clay material into powder, respectively carrying out acid washing treatment, washing to neutrality after finishing, and drying to obtain pretreated sillimanite powder and pretreated purple clay powder correspondingly;
(2) Grinding tea seed cake into powder, then carrying out acid washing treatment, washing to be neutral after finishing, and drying to obtain tea seed cake powder; tea seed meal powder and ZrO 2 Mixing the sol uniformly, and drying to obtain a pore-forming agent;
(3) Mixing the pretreated sillimanite powder obtained in the step (1) and the pretreated purple sand powder to obtain premixed powder, then adding the pore-forming agent obtained in the step (2), the polyvinyl alcohol aqueous solution and the CaO mineralizer, and uniformly mixing to obtain a mixture; the mass ratio of the pore-forming agent to the premixed powder is 1:5;
(4) Calcining the obtained mixture at 1600 ℃ to obtain mullite-based porous filler;
(5) FeCl is added 3 ·6H 2 O and FeSO 4 ·7H 2 O is dispersed in water and evenly mixed to obtain Fe 3 O 4 A mixed solution; then adding the mullite-based porous filler obtained in the step (4) into the mixed solution, and heatingMixing uniformly, regulating pH to be alkaline, and continuing heating reaction; after the reaction is finished, cooling, collecting a solid material through an externally applied magnetic field, washing and drying to obtain the magnetized mullite-based porous filler;
(6) Adding the obtained magnetized mullite-based porous filler into hexadecyl trimethyl ammonium bromide aqueous solution, heating for reaction, carrying out solid-liquid separation by using an external magnetic field after the reaction is finished, and drying to obtain the magnetized organic modified mullite-based porous filler.
2. The process according to claim 1, wherein in step (2), zrO 2 The mass fraction of the sol is 5-10wt%.
3. The method according to claim 1, wherein in the step (2), the tea seed cake powder is mixed with ZrO 2 The mass ratio of the sol is 1:1-3.
4. The method according to claim 1, wherein in the step (3), the mass fraction of the aqueous solution of polyvinyl alcohol relative to the total mass of the pore-forming agent and the premixed powder is 1 to 5%.
5. The method according to claim 1, wherein in the step (3), the mass fraction of CaO relative to the total mass of the pore-forming agent and the premixed powder is 1 to 5%.
6. The method according to claim 1, wherein in the step (5), the mullite-based porous filler is added in an amount of 8 to 10mg/mL relative to the mixed solution.
7. The magnetized organically modified mullite-based porous filler prepared by the preparation method of any one of claims 1 to 6.
8. The use of a magnetized organically modified mullite-based porous filler according to claim 7 for enriching highly efficient denitrifying bacteria.
9. The use of a magnetized organically modified mullite-based porous filler according to claim 7 in sewage treatment.
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