Sewage treatment biological filler, its preparation method and application

Abstract

The application discloses sewage treatment biological filler and a preparation method and application thereof, and comprises the following steps: S1, mixing sodium alginate solution and polyvinyl alcohol solution to obtain a first mixed solution; S2, grinding straws and then adding the straws into the first mixed solution to obtain a second mixed solution; S3, adding magnetic Fe3O4 particles into the second mixed solution, and freezing to obtain frozen particles; and S4, adding the frozen particles into a calcium chloride boric acid solution, and then drying to obtain the sewage treatment biological filler. The method can obtain a mixed biological filler of uniformly bonded sodium alginate, polyvinyl alcohol, straws and magnetic Fe3O4 particles, improves the adsorption performance and carbon release stability of the biological filler, and has a good sewage treatment effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sewage treatment, and particularly relates to a sewage treatment biological filler and a preparation method and application thereof. BACKGROUND

[0002] In order to achieve deep denitrification of low-carbon wastewater, the denitrification filter mainly adds liquid carbon sources such as methanol, sodium acetate and ethanol as electron donors to help denitrifying bacteria to denitrify for sewage treatment. Since the secondary pollution of the liquid carbon source is serious, the dosage is difficult to accurately control, and a solid carbon source with no toxicity, low cost and effective carbon release capacity needs to be found. In addition, due to the low density and dispersion of pollutants in water, the solid carbon source also needs to have a certain adsorption capacity to improve the carbon release efficiency.

[0003] Common solid organic carbon sources mainly include natural carbon release materials mainly based on cellulose, such as straw, rice husk, rotten wood and corn cob, but the mechanical properties are poor, the service life is short, the carbon release is unstable, the carbon source supply is more at first and less at last, and the sewage treatment effect is affected; biodegradable high molecular polymers artificially synthesized, such as polyhydroxyalkanoate (PHA), polylactic acid (PLA) and polylactone (PCL) materials, but the adsorption of pollutants is small, and the sewage treatment effect is poor.

[0004] Therefore, it is necessary to provide a solid biological filler with stable carbon release and good adsorption performance to improve the sewage treatment effect. SUMMARY

[0005] Therefore, the present application provides a sewage treatment biological filler and a preparation method and application thereof, which solves the problem of poor sewage treatment effect caused by unstable carbon release and low adsorption performance of solid organic carbon sources.

[0006] To achieve the above technical purpose, the present application adopts the following technical scheme:

[0007] In a first aspect, the present application provides a preparation method of a sewage treatment biological filler, comprising the following steps:

[0008] S1. mixing a sodium alginate solution and a polyvinyl alcohol solution to obtain a first mixed solution;

[0009] S2. grinding the straw and then adding it to the first mixed solution to obtain a second mixed solution;

[0010] S3. adding magnetic Fe3O4 particles to the second mixed solution, and then freezing to obtain frozen particles;

[0011] S4. adding the frozen particles to a calcium chloride-boric acid solution, and then drying to obtain the sewage treatment biological filler.

[0012] Preferably, the mass percentage concentration of sodium alginate in the second mixed solution is 0.5-0.8%.

[0013] Preferably, the mass percentage concentration of polyvinyl alcohol in the second mixed solution is 6-8%.

[0014] Preferably, the mass percentage concentration of straw in the second mixed solution is 10-20%.

[0015] Preferably, the straw is sorghum straw, and the length is 1-3mm.

[0016] Preferably, the particle size of the biological filler for sewage treatment is 5-10cm.

[0017] Preferably, the step S2 further comprises acid pickling the ground straw, the temperature of the acid pickling is 40-50℃, and the acid used for the acid pickling is 5-10% sulfuric acid.

[0018] Preferably, the temperature of the freezing in the step S3 is -18 to -20℃, and the temperature of the drying in the step S4 is 105-110℃.

[0019] In a second aspect, the application provides a biological filler for sewage treatment.

[0020] In a third aspect, the application provides an application of the biological filler for sewage treatment in treating sewage in a biological aerated filter.

[0021] The application has the following beneficial effects:

[0022] The scheme uses straw as the main carbon release body, polyvinyl alcohol (PVA) as the skeleton material, and sodium alginate (SA) as the pore-forming material to form a PVA-SA-straw mixture, and then the PVA-SA-straw mixture is compounded with magnetic Fe3O4 particles to form a uniformly bonded mixed biological filler. The biological filler involves the synergistic improvement of the adsorption capacity of the pollutants by physical and chemical adsorption. At the same time, the solubility of iron ions in the magnetic Fe3O4 particles and the pore-forming property of sodium alginate are utilized, and the pore-forming is performed by the temperature difference between freezing and drying, which improves the porosity of the biological filler, increases the adhesion rate of pollutants, microorganisms and other substances, and improves the adsorption performance of the filler and the sewage treatment effect.

[0023] The scheme utilizes the rigidity of polyvinyl alcohol and magnetic Fe3O4 particles to improve the mechanical properties of plant carbon release material straw, so as to stabilize the carbon release effect and improve the sewage purification capacity.

[0024] The raw materials of the biological filler of the application can be biodegraded, and are suitable for treating sewage in a biological aerated filter. DETAILED DESCRIPTION

[0025] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application.

[0026] The present application provides a preparation method of sewage treatment biological filler, comprising the following steps:

[0027] S1. obtaining a first mixed solution of sodium alginate solution and polyvinyl alcohol solution;

[0028] S2. grinding and then pickling the straw, and then adding it to the first mixed solution to obtain a second mixed solution;

[0029] S3. adding magnetic Fe3O4 particles to the second mixed solution, and then freezing to obtain frozen particles;

[0030] S4. adding the frozen particles to a calcium chloride-boric acid solution, and then drying, so that the polyvinyl alcohol and calcium ions contact to form a film and solidify, thereby obtaining the sewage treatment biological filler.

[0031] The above method obtains a mixed biological filler of uniformly bonded sodium alginate, polyvinyl alcohol, straw and magnetic Fe3O4 particles. The filler improves the adsorption performance and carbon release stability at the same time, and ultimately improves the sewage treatment capacity. The specific mechanism is as follows:

[0032] On the one hand, the PVA-SA-straw adsorption process is physical adsorption, and the PVA-SA-Fe3O4 particle adsorption process is chemical adsorption. Therefore, the biological filler of the present application has two ways of physical adsorption and chemical adsorption, and the adsorption capacity of the biological filler is improved through the synergistic effect of the two ways, and the denitrification effect is improved. On the other hand, when the mixed compound obtained by the present application is used in a sewage environment, iron ions in the magnetic Fe3O4 particles are dissolved. On the basis of the sodium alginate (SA) pore-forming of the biological filler itself, the internal pore structure is further improved, the surface area of the pollutants and microorganisms that can be attached is improved, and the pores caused by the sodium alginate (SA) also accelerate the dissolution of Fe3O4. The two work together to improve the porosity and increase the adsorption performance of the filler. Furthermore, from the process, the temperature difference formed by freezing and then drying allows the frozen particles to suddenly expand when heated, which is also beneficial to the improvement of the porosity and the improvement of the adsorption performance.

[0033] The present application adds polyvinyl alcohol as a skeleton material and an adhesive, and magnetic Fe3O4 particles as a filler, to enhance the mechanical properties of the sorghum straw, prolong the service life of the biological filler, and stabilize the stability of the sorghum straw as the main carbon release body.

[0034] Meanwhile, the magnetic Fe3O4 particles are used in the scheme, which is not only beneficial to denitrification, but also beneficial to phosphorus removal. The reason is that the magnetic Fe3O4 particles have a synergistic effect between autotrophic denitrification and heterotrophic denitrification. The combination of the two denitrification effects can significantly enhance the nitrogen removal effect of the biological filler. Moreover, the dissolved iron ions can react with the phosphate in the sewage to form a precipitate, thereby achieving the effect of phosphorus removal. Therefore, the denitrification and phosphorus removal effects are also improved.

[0035] In some embodiments, the mass percentage concentration of sodium alginate in the second mixed solution is 0.5-0.8%. The addition of sodium alginate is beneficial to improve the pore forming rate of polyvinyl alcohol embedding. However, too high sodium alginate concentration will reduce the mechanical properties of the biological filler. Too low sodium alginate concentration cannot form pores with polyvinyl alcohol, and cannot play the role of pore-forming material.

[0036] In some embodiments, the mass percentage concentration of polyvinyl alcohol in the second mixed solution is 6-8%. Polyvinyl alcohol (PVA) has strong hydrophilicity, which is beneficial to microbial biofilm formation. However, too high content will cause the self-made filler to be too dense. The strength of the biological filler made by 6%-8% polyvinyl alcohol is 15.5-20.3 MPa, which meets the strength requirements of the biological filter microbial carrier.

[0037] In some embodiments, the mass percentage concentration of the second mixed solution is 10-20%. If the mass concentration of the sorghum straw is too low, the self-made filler will be irregular in shape after drying, the spherical shape is not full, and the combination with PVA-SA is too tight, with fewer pores, which is not suitable for microbial growth and reproduction. If the mass concentration is too high, the PVA-SA cannot bond the sorghum straw powder, and the combination is too loose.

[0038] In the sewage treatment biological filler of the scheme, the length of the sorghum straw is 1-3 mm. Too long will cause the diameter of the filler to be too large, which does not meet the requirements of the filler. Too short will cause unstable bonding, causing the filter to be blocked.

[0039] The sewage treatment biological filler of the scheme is spherical, and the particle size is 5-10 cm. Too small will easily cause the biological filter to be blocked. Too large will cause the specific surface area to be reduced, and the filler cannot be fully utilized, wasting manpower and resources.

[0040] Preferably, the step S2 further comprises acid washing the ground sorghum straw. The acid washing temperature is 40-50℃, and the acid used for acid washing is 5-10% sulfuric acid. After the acid washing of the sorghum straw, the surface impurities are removed, and the fusion with the skeleton material polyvinyl alcohol is enhanced. The hydrophilicity of the biological filler is enhanced, which is beneficial to the formation of the biological membrane on the surface of the biological filter, and the biofilm formation is faster and simpler, thereby improving the adsorption capacity.

[0041] Preferably, the freezing temperature in step S3 is -18 to -20 DEG C, and the drying temperature in step S4 is 105-110 DEG C. The solid-liquid mixture is shaped into a spherical gel by freezing, and then dried at about 105 DEG C to evaporate or volatilize the water and volatile substances in the gel, thereby generating voids. Meanwhile, the drying has a certain carbonization effect, which can improve the adsorption capacity.

[0042] The application provides a sewage treatment biological filler, which comprises mutually bonded sodium alginate, polyvinyl alcohol, straw and magnetic Fe3O4 particles.

[0043] The application provides application of the sewage treatment biological filler in treatment of sewage in a biological aerated filter.

[0044] The application is further described below through specific examples.

[0045] Example 1

[0046] A preparation method of a sewage treatment biological filler comprises the following steps:

[0047] S1. 0.5 g of sodium alginate and 6 g of polyvinyl alcohol are weighed and added to 100 ml of water, and then dissolved at 80 DEG C to obtain a first mixed solution;

[0048] S2. 10 g of sorghum straw is ground into 3 mm short rods, and then subjected to acid pickling with 5% sulfuric acid at 40 DEG C, and then added to the first mixed solution to obtain a second mixed solution;

[0049] S3. After 1 g of magnetic Fe3O4 particles is added to the second mixed solution, the mixture is poured into a spherical mold with a diameter of 5 cm, and then frozen at -18 DEG C for 12 h to obtain frozen particles;

[0050] S4. The frozen particles are soaked in a boric acid solution containing 4% calcium chloride, and then dried at 105 DEG C for 12 h to obtain the sewage treatment biological filler.

[0051] Example 2

[0052] A preparation method of a sewage treatment biological filler, which is the same as that in example 1 except that the amount of sodium alginate is 0.8 g.

[0053] Example 3

[0054] A preparation method of a sewage treatment biological filler, which is the same as that in example 1 except that the amount of polyvinyl alcohol is 8 g.

[0055] Comparative Example 1

[0056] A method for preparing a sewage treatment biological filler, other contents are the same as example 1, the difference is that no magnetic Fe3O4 particles are added, and PVA-SA-highway straw particles are obtained.

[0057] Comparative example 2

[0058] A method for preparing a sewage treatment biological filler, other contents are the same as example 1, the difference is that no magnetic Fe3O4 particles are added, and PVA-SA-highway straw particles are obtained.

[0059] Evaluation test

[0060] The biological fillers obtained in example 1 and comparative examples 1-2 are tested for adsorption capacity and carbon release stability, and adsorption kinetics fitting experiment (GB / T 6287-2021).

[0061] Adsorption capacity test: the adsorption capacity of methylene blue of the biological fillers obtained in example 1 and comparative examples 1-2 is evaluated, and three materials (PVA-SA-highway straw, PVA-SA-Fe3O4 particles, PVA-SA-highway straw-Fe3O4 particles) (solid-liquid ratio is 1:500) are stirred and adsorbed in a constant temperature water bath at a temperature of 25°C, and the clarified solution is obtained at a specified time (5, 10, 20, 30, 40, 60, 80, 120 and 140 min), the absorbance value is measured at a wavelength of 665 nm and recorded. After the test, the corresponding methylene blue concentration is calculated according to the measured absorbance value and the methylene blue standard curve, and the results are shown in table 1.

[0062] Table 1 comparison of adsorption capacity test of different fillers

[0063]

[0064] Methylene blue is a medium-sized aromatic dyeing agent with polarity and linear structure. The adsorption time and adsorption amount of methylene blue on the filler reflect the adsorption capacity of the filler for molecules characterized by polarity and linear structure, and can reflect the adsorption of nitrogen-containing pollutants by the filler. The removal effect of the three materials on methylene blue is in the order of example 1 (PVA-SA-highway straw-Fe3O4 particles) > comparative example 1 (PVA-SA-highway straw) > comparative example 2 (PVA-SA-Fe3O4 particles). The adsorption performance of example 1 is higher than that of comparative examples 1 and 2, which shows that PVA-SA-highway straw-Fe3O4 particles have a significant promoting effect on the adsorption of pollutants.

[0065] Carbon release stability test: equal amounts of biological filler of example 1, comparative examples 1-2 were respectively added into conical flasks, and then 1000ml of distilled water was respectively added. The flasks were sealed and placed at constant temperature of 25℃, and samples for measuring chemical oxygen demand (COD) concentration were extracted at 0h, 1h, 4h, 7h, 12h, 24h, 36h, 2d, 3d, 3d, 4d, 5d, 6d, 7d, 8d, 9d, 10d, 12d, 14d, 16d, 18d, 20d, 22d, 24d. The three kinds of solid carbon release sources in the slow release stage were fitted by using zero-order linear equation, and the results are shown in Table 2;

[0066] Table 2 Kinetic release equation fitting

[0067]

[0068] The results show that the biological filler of example 1 has the highest R 2 in the slow release stage, reaching 0.995, indicating that the biological filler of the present scheme can continuously and stably provide carbon source in sewage treatment, has high carbon release stability, and can improve the treatment effect of sewage treatment by biological filter.

[0069] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any change or replacement easily thought by those skilled in the art within the technical range disclosed by the present application should be covered in the protection scope of the present application.

Claims

1. A method for preparing a biological packing material for wastewater treatment, characterized in that, Includes the following steps: S1. Mix sodium alginate solution and polyvinyl alcohol solution to obtain the first mixture; S2. After grinding the straw, add it to the first mixture to obtain the second mixture; S3. Add magnetic Fe3O4 particles to the second mixture, freeze, and obtain frozen particles; S4. The frozen particles are added to a calcium chloride boric acid solution and then dried to obtain the wastewater treatment biological packing material; Step S2 also includes acid washing of the ground straw at a temperature of 40-50°C and using 5-10% sulfuric acid; the freezing temperature in step S3 is -18 to -20°C; and the drying temperature in step S4 is 105-110°C.

2. The method for preparing biological packing material for wastewater treatment according to claim 1, characterized in that, In the second mixture, the mass percentage concentration of sodium alginate is 0.5-0.8%.

3. The method for preparing biological packing material for wastewater treatment according to claim 1, characterized in that, In the second mixture, the mass percentage concentration of polyvinyl alcohol is 6-8%.

4. The method for preparing biological packing material for wastewater treatment according to claim 1, characterized in that, In the second mixture, the mass percentage concentration of straw is 10-20%.

5. The method for preparing biological packing material for wastewater treatment according to claim 1, characterized in that, The straw is sorghum straw, and the length of the straw is 1-3mm.

6. The method for preparing biological packing material for wastewater treatment according to claim 1, characterized in that, The particle size of the biological packing material for wastewater treatment is 5-10 cm.

7. A wastewater treatment biological packing material obtained by the preparation method according to any one of claims 1-6.

8. The application of the wastewater treatment biological packing material as described in claim 7 in the treatment of wastewater in an aerated biological filter.

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