A small-particle-size mud film particle and its sewage treatment method

Abstract

The present application discloses a small-sized sludge film particle and a sewage treatment method thereof. The small-sized sludge film particle comprises a biological enhancement carrier and an active biological bactericide with a mass ratio of 1:(0.2-0.4); the raw materials of the biological enhancement carrier comprise mesoporous silica and polyvinyl alcohol with a mass ratio of 1:(0.5-0.7). The small particle size of the mesoporous silica enables the formed sludge film particles to be stabilized within a relatively small particle size range. Its excellent pore structure provides a good living environment for microorganisms, forming a spatial layered structure with anaerobic inside, facultative aerobic in the middle, and aerobic outside. The mass transfer performance, decontamination ability and stability are improved. Polyvinyl alcohol is connected to the surface of the mesoporous silica, and its hydrophilicity is beneficial to increasing the microorganism fixation ability of the biological enhancement carrier.

Description

Technical Field

[0001] The present application relates to the field of sewage treatment, and particularly to a small-sized sludge film particle and a sewage treatment method thereof. Background Art

[0002] The activated sludge technology is an artificial enhancement of the self-purification of natural water bodies, which can remove biodegradable organic matter and other substances in dissolved and colloidal states in sewage. Aerobic sludge particles are biological aggregates formed by the self-flocculation of microorganisms under the action of a selection pressure. Compared with the traditional activated sludge technology, they have the advantages of high sludge concentration, strong toxicity resistance, impact load resistance, and simultaneous nitrogen and phosphorus removal.

[0003] However, during the cultivation of aerobic sludge particles, due to the different diffusion efficiencies of substrates, nutrients, etc. inside the granular sludge, the excessive growth of filamentous bacteria that support aerobic sludge particles or the formation of zoogloea connected by filamentous bacteria under the impact of water flow lead to a large loss of nitrifying bacteria contained in aerobic sludge particles and slow recovery of growth, thereby reducing the stability of aerobic sludge particles. At the same time, aerobic sludge particles have a relatively large particle size, with an average particle size of 1-3 mm, so the mass transfer effects of dissolved oxygen and target removal substances are poor, and the microbial activity inside the particles is low, which also reduces the stability of aerobic sludge particles. Summary of the Invention

[0004] To solve the problems of poor stability of aerobic sludge particles and poor mass transfer effect caused by the large particle size formed, the present application provides a small-sized sludge film particle and a sewage treatment method thereof.

[0005] In a first aspect, the present application provides a small-sized sludge film particle, which includes flocculent sludge, a biological enhancement carrier, and an active biological bactericide; the raw materials of the biological enhancement carrier include mesoporous silica and polyvinyl alcohol with a mass ratio of 1:(0.5-0.7).

[0006] Preferably, the particle size of the small-sized sludge film particle is 100-300 μm.

[0007] Preferably, the particle size of the mesoporous silica is 20-50 nm.

[0008] Preferably, the polyvinyl alcohol is a fully alcoholized polyvinyl alcohol with an average degree of polymerization of 1500-2000.

[0009] By adopting the above technical solutions, the active biological bactericide is fixed on the biological enhancement carrier by film formation. The raw materials of the biological enhancement carrier include mesoporous silica and polyvinyl alcohol, both of which have good biocompatibility and no toxic effect on microorganisms.

[0010] Mesoporous silica has a rich pore structure with interconnected or closed pores. Fixing microorganisms on mesoporous silica can effectively immobilize the microbial flora contained in the active biological strains, maintain good shock resistance, and resist the impact on microorganisms caused by changes in sludge load and volume load during the influent process, thereby enhancing the structural stability of small-sized sludge film particles. The high porosity of mesoporous silica can also accommodate continuously proliferating microorganisms, increasing the cell concentration in the biological augmentation carrier and improving the efficiency of sewage treatment. At the same time, substances such as dissolved oxygen and target removal substances can be transported through the pores in mesoporous silica, which is beneficial to the growth of aerobic bacteria on the carrier and the discharge of substances such as nitrogen gas generated during the denitrification process. The high framework rigidity of mesoporous silica is also conducive to maintaining the stability of the granular sludge film.

[0011] However, due to the relatively smooth surface of mesoporous silica and the lack of a large number of positive charges, when mesoporous silica is used as a carrier, its ability to attract the aggregation of microorganisms is weak, and its adhesion ability to microorganisms is poor. During the cultivation process of sludge film particles, it is difficult for active biological agents to grow and reproduce in large quantities on mesoporous silica as a carrier. Polyvinyl alcohol has excellent hydrophilicity and contains sufficient positive charges, which can provide a good microenvironment for the fixation and metabolism of microorganisms, making up for the defect that mesoporous silica is difficult to attract the aggregation and reproduction of microorganisms. At the same time, connecting part of polyvinyl alcohol on the surface of mesoporous silica can also increase the water-insolubility of polyvinyl alcohol and the fixation of microorganisms by the biological augmentation carrier, which is beneficial to increasing the stability of small-sized sludge film particles.

[0012] Mesoporous silica also has a small particle size of 20 - 50 nm. As a carrier, it can ensure that the average particle size of the formed sludge film particles remains within a small range during the subsequent cultivation process of small-sized sludge film particles, enabling the formed small-sized sludge film particles to have a larger specific surface area and better mass transfer efficiency.

[0013] Naturally formed aerobic sludge particles have a large particle size and can form a spatial stratification structure with anaerobic inside, facultative anaerobic in the middle, and aerobic outside. In the case of small particle sizes, the biomass of aerobic sludge particles is small and a large number of aerobic bacteria die, resulting in poor particle stability and difficulty in maintaining this spatial structure. Due to the good pore structure and high porosity in mesoporous silica, there is a large space for the growth and reproduction of microorganisms, which does not affect the formation of an internal anaerobic, middle facultative anaerobic, and external aerobic spatial stratification structure by the added active biological agents on the biological augmentation carrier. It can achieve the removal of COD and nitrogen and phosphorus while also having the high specific surface area and high mass transfer efficiency of small particle sizes.

[0014] Preferably, the raw materials of the mesoporous silica include a composite template agent and tetraethyl orthosilicate with a mass ratio of (0.1 - 0.3):1; the composite template agent includes one or a combination of octadecyl dimethyl ammonium bromide, polyvinylpyrrolidone, and sodium dodecyl sulfate.

[0015] Preferably, the preparation process of the mesoporous silica is as follows: Add the composite template agent to deionized water and stir to completely dissolve it, then add tetraethyl orthosilicate, and stir and react at 35-45 °C in a water bath for 20-24 h; After the reaction is completed, transfer it to a hydrothermal autoclave for aging crystallization for 24-26 h. Put the aged crystallization product through drying and grinding into a muffle furnace, calcine it at 500-600 °C for 5-7 h, and then grind it to obtain mesoporous silica.

[0016] Preferably, the aging crystallization temperature is 90-120 °C.

[0017] By adopting the above technical solution, the micelles formed by the composite template agent in water can induce the formation of the morphology of mesoporous silica. The composite template agent and hydrolyzed tetraethyl orthosilicate are assembled into the mesoporous silica skeleton structure. After aging crystallization, the composite template agent is removed by calcination in a muffle furnace to obtain a mesoporous silica material with a pore structure.

[0018] Preferably, the raw materials of the biological enhancement carrier further include an amino silane coupling agent and a basic catalyst; the addition amount of the amino silane coupling agent is 0.5-1.5% of the mass of the mesoporous silica; the addition amount of the basic catalyst is 0.2-0.4% of the mass of the mesoporous silica.

[0019] Preferably, the amino silane coupling agent includes one or more of γ-aminopropyltriethoxysilane and γ-aminopropyltrimethoxysilane; the basic catalyst includes one or more of potassium hydroxide, sodium hydroxide, and alkyl sodium chloride.

[0020] Preferably, the preparation process of the biological enhancement carrier is as follows:

[0021] Modification treatment of mesoporous silica: Add mesoporous silica to deionized water and disperse it evenly, then add an amino silane coupling agent, stir and react at 60-80 °C in a water bath for 5-7 h, and then obtain modified mesoporous silica through centrifugation, washing, and drying.

[0022] Preparation of the biological enhancement carrier: Dissolve polyvinyl alcohol fully in deionized water, take the modified mesoporous silica and disperse it in deionized water, add the polyvinyl alcohol solution and the basic catalyst, stir and react at 80-90 °C in a water bath, and then obtain the biological enhancement carrier through centrifugation, washing, and drying.

[0023] Preferably, in the preparation process of the biological enhancement carrier, the dissolution temperature of polyvinyl alcohol is 50-60 °C.

[0024] By adopting the above technical solution, the mesoporous silica has poor dispersibility and is prone to agglomeration in water, making it difficult to play the role of a carrier. Under the condition of the presence of water, the amino-silane coupling agent will hydrolyze, and the contained ethoxy groups are preferentially hydrolyzed into hydroxyl groups, which react with the hydroxyl groups on the surface of the mesoporous silica, dehydrate to form siloxane bonds, achieving the effect of modifying the surface of the mesoporous silica and enhancing the dispersibility of the mesoporous silica. And after the modification treatment, the physicochemical properties of the surface of the mesoporous silica change, which can provide good chemical bonding conditions for the subsequent immobilization of polyvinyl alcohol. The silanol groups contained on the surface of the mesoporous silica can react with the alcohol hydroxyl groups in the polyvinyl alcohol molecules under the catalysis of the ion pairs formed by the alkaline catalyst to further form silanol esters. The polyvinyl alcohol is tightly connected to the surface of the mesoporous silica through chemical bonding, enhancing the affinity and fixation of the mesoporous silica for microorganisms, thereby increasing the stability of the small-particle sludge film particles.

[0025] Preferably, water-soluble chitosan is further added during the preparation process of the bioaugmentation carrier; the molecular weight of the water-soluble chitosan is 2.0×10 5 ~3.0×10 5 .

[0026] Preferably, the addition amount of the water-soluble chitosan is 15% - 25% of the mass of the polyvinyl alcohol.

[0027] By adopting the above technical solution, polyvinyl alcohol has good water solubility. Although its water insolubility is significantly improved after being bonded with mesoporous silica, during the sewage treatment process, when the influent load is large, the polyvinyl alcohol is prone to hydrolysis, causing the bioaugmentation carrier to gradually lose its function and greatly reducing the service life. On the one hand, the water-soluble chitosan has good biocompatibility and does not inhibit the growth and reproduction of microorganisms. On the other hand, the contained amino groups can form hydrogen bonds with the hydroxyl groups contained in the polyvinyl alcohol, gradually forming a cross-linked network structure on the surface of the mesoporous silica, which can effectively fix the polyvinyl alcohol and prevent the polyvinyl alcohol from being hydrolyzed and losing its function during the sewage treatment process.

[0028] Preferably, the active bio-bacterial agent includes one or a combination of several of composite COD bacteria, composite denitrifying bacteria, composite polyphosphorus-removing bacteria, composite desulfurizing bacteria, composite oil-removing bacteria, and composite salt-tolerant bacteria.

[0029] By adopting the above technical solution, the active bio-bacterial agent is immobilized in the bioaugmentation carrier through film formation. The contained bacterial agents include aerobic bacteria and anaerobic bacteria, forming a three-layer spatial structure of external aerobic, middle facultative aerobic, and internal anaerobic on the bioaugmentation carrier, which can carry out the synchronous nitrification and denitrification processes in a full-coverage and all-time manner. At the same time, the active bio-bacterial agent has strong stress resistance and can resist sewage with poor nutrition or nutritional imbalance at the same time.

[0030] Preferably, the bioaugmentation carrier further includes a nutrient agent accounting for 3% to 8% of the mass of the bioaugmentation carrier; the nutrient agent includes one or a combination of glucose, sodium citrate, potassium phosphate, sodium chloride, peptone, and yeast extract.

[0031] By adopting the above technical solution, the bioaugmentation carrier already contains the nutrient components for the growth and reproduction of microorganisms, and no additional nutrients need to be supplemented.

[0032] In a second aspect, the present application also provides a sewage treatment method for small particle size mud film particles, including the following steps: Sewage enters the HJDL (short-process nitrogen and phosphorus removal process) reaction tank through a grille. Combining with the biological incubation system in the HJDL reaction tank, the bioaugmentation carrier and the active biological bactericide are put into the incubation system to form small particle size mud film particles and remove impurities in the sewage; the water treated by the HJDL reaction tank enters the secondary sedimentation tank. The middle layer sludge in the secondary sedimentation tank is re-discharged into the HJDL reaction tank for treatment, and the sewage with qualified water quality indicators after sedimentation treatment in the secondary sedimentation tank is discharged; the HJDL reaction tank also includes a stirring device and a reflux device.

[0033] By adopting the above technical solution, the HJDL reaction tank contains a biological incubation system. After the sewage enters, the flocculent sludge therein combines with the bioaugmentation carrier and the active biological bactericide to gradually form small particle size mud film particles under the action of the secreted EPS, thereby treating and converting the harmful substances in the sewage. The stirring device in the HJDL reaction tank can keep the mud, water, and bacteria inside the entire HJDL reaction tank in a continuous motion state, and the reflux device sends the existing bioaugmentation carrier and active biological bactericide to the top of the incubation system reactor to continuously complete the granulation process of the small particle size mud film particles.

[0034] In summary, the present application has the following beneficial effects:

[0035] 1. A small particle size mud film particle of the present application includes a bioaugmentation carrier. The raw material of the bioaugmentation carrier includes mesoporous silica. The rich pore structure of mesoporous silica can accommodate the growth and reproduction of microorganisms, which is beneficial to improving the mass transfer efficiency. The high-rigidity skeleton is also beneficial to maintaining the stability of the mud film particles; the small particle size of mesoporous silica as a carrier can ensure that the average particle size of the formed mud film particles is maintained within a small range, and while having a high specific surface area, stably maintain the spatial stratification structure of anaerobic inside, facultative in the middle, and aerobic outside.

[0036] 2. A small particle size mud film particle of the present application includes a bioaugmentation carrier, and the bioaugmentation carrier further includes polyvinyl alcohol. Since the microbial attachment ability of mesoporous silica is poor, after surface modification, it is connected with polyvinyl alcohol. The high hydrophilicity of polyvinyl alcohol can provide a good microenvironment for the fixed microbial metabolism and proliferation, increasing the fixation ability of the bioaugmentation carrier to microorganisms and the structural stability of the small particle size mud film particles. At the same time, the bioaugmentation carrier also contains water-soluble chitosan, which can form hydrogen bonds with polyvinyl alcohol, thereby forming a cross-linked network structure, enhancing the water-insolubility of polyvinyl alcohol, and increasing the service life of the bioaugmentation carrier. Detailed implementation mode

[0037] Preparation example of mesoporous silica

[0038] Preparation example 1-1, a kind of mesoporous silica, is prepared according to the following steps:

[0039] Take 6g of octadecyl dimethyl ammonium bromide and add it to 100ml of deionized water, stir until completely dissolved. At the same time, take 14g of polyvinylpyrrolidone and add it to 100ml of deionized water and stir until completely dissolved. Mix the two obtained solutions evenly and then dropwise add 100g of tetraethyl orthosilicate, and stir and react at 40°C in a water bath for 24h. Transfer the reacted solution to a hydrothermal kettle and age and crystallize at 100°C for 24h. Dry and grind the obtained product and then put it into a muffle furnace, calcine at 550°C for 6h, and then grind to obtain mesoporous silica.

[0040] Preparation example 1-2, a kind of mesoporous silica, the difference from preparation example 1-1 is only that the addition amount of octadecyl dimethyl ammonium bromide is 3g and the addition amount of polyvinylpyrrolidone is 7g.

[0041] Preparation example 1-3, a kind of mesoporous silica, the difference from preparation example 1-1 is only that the addition amount of octadecyl dimethyl ammonium bromide is 12g and the addition amount of polyvinylpyrrolidone is 18g.

[0042] Preparation example 1-4, a kind of mesoporous silica, the difference from preparation example 1-1 is only that the addition amount of octadecyl dimethyl ammonium bromide is 2g and the addition amount of polyvinylpyrrolidone is 6g.

[0043] Preparation example 1-5, a kind of mesoporous silica, the difference from preparation example 1-1 is only that the addition amount of octadecyl dimethyl ammonium bromide is 14g and the addition amount of polyvinylpyrrolidone is 20g.

[0044] Preparation example of bioaugmentation carrier

[0045] Preparation example 2-1, a kind of bioaugmentation carrier, is prepared according to the following method:

[0046] Take 100 g of the mesoporous silica prepared in Preparation Example 1-1 and add it to 500 ml of deionized water. Stir evenly to disperse it in water by magnetic stirring, add 1 g of γ-aminopropyltriethoxysilane, and stir and react at 70 °C in a water bath for 6 h. After centrifugation, wash with anhydrous ethanol solution, and obtain modified mesoporous silica after drying.

[0047] Take 60 g of polyvinyl alcohol (average degree of polymerization is 1750) and add it to 1000 ml of deionized water. Stir at 55 °C in a water bath until completely dissolved. Then take 100 g of the modified mesoporous silica and disperse it evenly in 500 ml of deionized water. Add the obtained polyvinyl alcohol aqueous solution and 0.3 g of potassium hydroxide, and stir and react at 90 °C in a water bath for 10 h. After centrifugation, wash alternately with deionized water and anhydrous ethanol, and then dry at 80 °C and grind to obtain a biological synergistic carrier.

[0048] Preparation Examples 2-2 to 2-5, a biological synergistic carrier, which is different from Preparation Example 2-1 only in that the ratio of the raw materials used changes. The specific raw material formula is shown in Table 1:

[0049] Table 1 Formulas of Preparation Examples 2-1 to 2-5

[0050]

[0051] The mesoporous silica used in Preparation Examples 2-2 to 2-5 is all the mesoporous silica prepared in Preparation Example 1-1.

[0052] Preparation Example 2-6, a biological synergistic carrier, which is different from Preparation Example 2-1 only in that the mesoporous silica prepared in Preparation Example 1-2 is used to replace the mesoporous silica prepared in Preparation Example 1-1 in equal amounts.

[0053] Preparation Example 2-7, a biological synergistic carrier, which is different from Preparation Example 2-1 only in that the mesoporous silica prepared in Preparation Example 1-3 is used to replace the mesoporous silica prepared in Preparation Example 1-1 in equal amounts.

[0054] Preparation Example 2-8, a biological synergistic carrier, which is different from Preparation Example 2-1 only in that the addition amount of polyvinyl alcohol is 40 g.

[0055] Preparation Example 2-9, a biological synergistic carrier, which is different from Preparation Example 2-1 only in that the addition amount of polyvinyl alcohol is 80 g.

[0056] Preparation Example 2-10, a biological synergistic carrier, which is different from Preparation Example 2-1 only in that the mesoporous silica prepared in Preparation Example 1-4 is used to replace the mesoporous silica prepared in Preparation Example 1-1 in equal amounts.

[0057] Preparation Example 2-11, a biological synergistic carrier, which is different from Preparation Example 2-1 only in that the mesoporous silica prepared in Preparation Example 1-5 is used to replace the mesoporous silica prepared in Preparation Example 1-1 in an equal amount.

[0058] Preparation Example 2-12, a biological synergistic carrier, which is different from Preparation Example 2-1 only in that 12 g of water-soluble chitosan (deacetylation degree 45%, molecular weight 2.5×10 5 ) is further added to the aqueous solution of polyvinyl alcohol.

[0059] Preparation Example 2-13, a biological synergistic carrier, which is different from Preparation Example 2-1 only in that polyvinyl alcohol is not added.

[0060] Preparation Example 2-14, a biological synergistic carrier, is prepared according to the following method:

[0061] Take 100 g of polyvinyl alcohol (average degree of polymerization 1750) and add it to 1000 ml of deionized water. Stir at 80°C in a water bath until completely dissolved. Add 3 g of N,N-dimethylacetamide solution. After stirring evenly, add it to 500 ml of acetone solution for curing reaction. After the curing is completed, filter out the obtained gel beads and add 200 ml of 50 wt% glutaraldehyde solution and 500 ml of 20 wt% hydrochloric acid solution. Stir evenly and then carry out a chemical cross-linking reaction. Then wash with deionized water and dry to obtain a polyvinyl alcohol carrier.

[0062] Examples

[0063] Example 1, a sewage treatment method for small particle size mud film particles, is carried out according to the following method:

[0064] The sewage flows into the HJDL (short process denitrification and phosphorus removal process) reaction tank after passing through the grid filtration. Combining with the biological incubation system in the HJDL reaction tank, the biological synergistic carrier prepared in Preparation Example 2-1 and the active biological bactericide with a mass ratio of 1:0.3 are put into the incubation system. Among them, a nutrient agent with a mass of 5% of the carrier mass is also added to the biological synergistic carrier to form small particle size mud film particles and treat the impurities in the sewage; the treated sewage flows into the secondary sedimentation tank. The middle layer sludge in the secondary sedimentation tank flows back into the HJDL reaction tank for secondary treatment, and the sewage with qualified water quality indicators after sedimentation treatment in the secondary sedimentation tank is discharged.

[0065] Among them, the active biological bactericide is a combined bactericide with a ratio of m (compound COD bacteria): m (compound denitrifying bacteria): m (compound phosphorus-accumulating bacteria): m (compound desulfurizing bacteria): m (compound oil-removing bacteria): m (compound salt-tolerant bacteria) = 2:3:2:1:1:1. The nutrient agent is a compound nutrient agent with a ratio of m (sodium citrate): m (glucose): m (potassium phosphate): m (sodium chloride): m (peptone): m (yeast extract) = 0.8:1:2:0.2:4:2.

[0066] Example 2, a sewage treatment method for small-sized sludge film particles, which is only different from Example 1 in that the biological enhancement carrier prepared in Preparation Example 2-2 is used to replace the biological enhancement carrier prepared in Preparation Example 2-1 in equal amount, and the mass ratio of the biological enhancement carrier prepared in Preparation Example 2-2 to the active biological bactericide is 1:0.2.

[0067] Example 3, a sewage treatment method for small-sized sludge film particles, which is only different from Example 1 in that the biological enhancement carrier prepared in Preparation Example 2-3 is used to replace the biological enhancement carrier prepared in Preparation Example 2-1 in equal amount, and the mass ratio of the biological enhancement carrier prepared in Preparation Example 2-3 to the active biological bactericide is 1:0.4.

[0068] Example 4, a sewage treatment method for small-sized sludge film particles, which is only different from Example 1 in that the biological enhancement carrier prepared in Preparation Example 2-6 is used to replace the biological enhancement carrier prepared in Preparation Example 2-1 in equal amount, and the addition amount of the nutrient agent is 3% of the mass of the biological enhancement carrier prepared in Preparation Example 2-6.

[0069] Example 5, a sewage treatment method for small-sized sludge film particles, which is only different from Example 1 in that the biological enhancement carrier prepared in Preparation Example 2-7 is used to replace the biological enhancement carrier prepared in Preparation Example 2-1 in equal amount, and the addition amount of the nutrient agent is 8% of the mass of the biological enhancement carrier prepared in Preparation Example 2-6.

[0070] Example 6, a sewage treatment method for small-sized sludge film particles, which is only different from Example 1 in that the biological enhancement carrier prepared in Preparation Example 2-4 is used to replace the biological enhancement carrier prepared in Preparation Example 2-1 in equal amount.

[0071] Example 7, a sewage treatment method for small-sized sludge film particles, which is only different from Example 1 in that the biological enhancement carrier prepared in Preparation Example 2-5 is used to replace the biological enhancement carrier prepared in Preparation Example 2-1 in equal amount.

[0072] Example 8, a sewage treatment method for small-sized sludge film particles, which is only different from Example 1 in that the biological enhancement carrier prepared in Preparation Example 2-8 is used to replace the biological enhancement carrier prepared in Preparation Example 2-1 in equal amount.

[0073] Example 9. A sewage treatment method for small particle-size mud film particles, which is only different from Example 1 in that the bioaugmentation carrier prepared in Preparation Examples 2-9 is used to replace the bioaugmentation carrier prepared in Preparation Examples 2-1 in equal amounts.

[0074] Example 10. A sewage treatment method for small particle-size mud film particles, which is only different from Example 1 in that the bioaugmentation carrier prepared in Preparation Example 2-10 is used to replace the bioaugmentation carrier prepared in Preparation Examples 2-1 in equal amounts.

[0075] Example 11. A sewage treatment method for small particle-size mud film particles, which is only different from Example 1 in that the bioaugmentation carrier prepared in Preparation Example 2-11 is used to replace the bioaugmentation carrier prepared in Preparation Examples 2-1 in equal amounts.

[0076] Example 12. A sewage treatment method for small particle-size mud film particles, which is only different from Example 1 in that the bioaugmentation carrier prepared in Preparation Example 2-12 is used to replace the bioaugmentation carrier prepared in Preparation Examples 2-1 in equal amounts.

[0077] Example 13. A sewage treatment method for small particle-size mud film particles, which is only different from Example 1 in that the mass ratio of the bioaugmentation carrier prepared in Preparation Example 2-1 to the active biological bacteria agent is 1:0.1.

[0078] Example 14. A sewage treatment method for small particle-size mud film particles, which is only different from Example 1 in that the mass ratio of the bioaugmentation carrier prepared in Preparation Example 2-1 to the active biological bacteria agent is 1:0.5.

[0079] Example 15. A sewage treatment method for small particle-size mud film particles, which is only different from Example 1 in that no nutrient agent is added.

[0080] Comparative Example

[0081] Comparative Example 1. A sewage treatment method for small particle-size mud film particles, which is only different from Example 1 in that the bioaugmentation carrier prepared in Preparation Example 2-13 is used to replace the bioaugmentation carrier prepared in Preparation Examples 2-1 in equal amounts.

[0082] Comparative Example 2. A sewage treatment method for small particle-size mud film particles, which is only different from Example 1 in that the bioaugmentation carrier prepared in Preparation Example 2-14 is used to replace the bioaugmentation carrier prepared in Preparation Examples 2-1 in equal amounts.

[0083] Comparative Example 3. A sewage treatment method for small particle-size mud film particles, which is only different from Example 1 in that no bioaugmentation carrier is added.

[0084] Performance Detection Test

[0085] 1. Average particle size test of small particle size mud film particles: The particle size of the formed small particle size mud film particles was tested by laser particle size analysis method. During the test process, five groups of samples were taken for testing respectively, and then the average value was taken to obtain the average particle size of the small particle size mud film particles.

[0086] Among them, the laser particle size analyzer used is the particle size analyzer of Shimadzu model SALD-2300.

[0087] 2. COD removal rate in wastewater: The COD content in the sewage was tested by the potassium dichromate titration method according to GB / T 34500.2-2017 Chemical Analysis Methods for Rare Earth Residues and Wastewater - Part 2: Determination of Chemical Oxygen Demand (COD). The COD content in the sewage selected for testing was 300 - 350 mg / L. The COD content in the sewage before and after being treated by Examples 1 - 15 and Comparative Examples 1 - 3 was tested. The sewage inflow was 200 m 3 / d, and the treatment time was 7 days. The COD removal rate was calculated, and the calculation formula was as follows:

[0088]

[0089] Among them, C1 refers to the COD content in the sewage before treatment, and C2 refers to the COD content in the sewage after treatment.

[0090] 3. Nitrogen and phosphorus removal rates in wastewater: The total phosphorus content in the sewage was determined according to GB / T 11893-1989 Determination of Total Phosphorus in Water Quality - Ammonium Molybdate Spectrophotometric Method; the total nitrogen content in the sewage was determined according to HJ 636-2012 Determination of Total Nitrogen in Water Quality - Alkaline Potassium Persulfate Digestion UV Spectrophotometric Method. The total phosphorus and total nitrogen contents in the sewage before treatment and after being treated by Examples 1 - 15 and Comparative Examples 1 - 3 were tested. The sewage inflow was 200 m 3 / d, and the treatment time was 7 days. The calculation formulas were as follows:

[0091]

[0092]

[0093] Among them, P1 refers to the total phosphorus content in the sewage before treatment, P2 refers to the total phosphorus content in the sewage after treatment; N1 refers to the total phosphorus content in the sewage before treatment, and N2 refers to the total phosphorus content in the sewage after treatment.

[0094] 4. Stability test of small-sized sludge film particles: Adjust the COD content in the sewage participating in the test. On the third day, suddenly adjust it from the original 300 - 350 mg / L to 500 - 550 mg / L. By increasing the sludge load, the stability of small-sized sludge film particles is tested. The treatment time is still 7 days. The COD removal rate of the sewage is tested according to the method of Experiment 2.

[0095] The above test results are shown in Table 2.

[0096] Table 2 Test results of sewage treatment with small-sized sludge film particles

[0097]

[0098]

[0099] According to Table 2, combined with Example 1 and Comparative Example 1, it can be seen that the particle size of the sludge film particles in Comparative Example 1 is significantly larger than that in Example 1. The ability to remove COD, total nitrogen, and total phosphorus in the sewage has decreased significantly compared with Example 1. After increasing the sewage load, the COD removal rate has decreased significantly, indicating that the stability and the ability to remove sewage impurities in Comparative Example 1 have decreased significantly compared with Example 1, and the particle size of the sludge film particles is significantly larger than that in Example 1. The reason may be that polyvinyl alcohol was not added to the biological enhancement carrier in Comparative Example 1. Since mesoporous silica does not carry a large amount of positive charges on its surface and the surface is relatively smooth, its adsorption capacity for microorganisms is weak, and the number of active biological agents attached to mesoporous silica during growth decreases. Some active biological agents directly form aerobic sludge particles with the flocculent sludge in the sewage during the growth and reproduction process, resulting in a significant increase in the average particle size. At the same time, some active biological agents do not use the biological enhancement carrier as a carrier and are not protected by mesoporous silica. When the sewage load increases, the stability decreases, and all removal rates decrease significantly.

[0100] Combined with Example 1 and Comparative Example 2, it can be seen that the particle size of the mud film in Comparative Example 2 is significantly larger than that in Example 1. The ability to remove COD, total nitrogen, and total phosphorus in sewage has decreased compared to Example 1. After increasing the sewage load, the COD removal rate has decreased significantly, indicating that the stability and the ability to remove sewage impurities in Comparative Example 2 have decreased significantly compared to Example 1, and the particle size of the mud film is significantly larger than that in Example 1. The reason may be that in Comparative Example 2, the mud film particles with polyvinyl alcohol as the biological enhancement carrier were used for sewage treatment. The good hydrophilicity of polyvinyl alcohol in water makes the particle size formed during the preparation of the carrier larger, and finally the particle size of the formed mud film is also larger. At the same time, when polyvinyl alcohol is used as the carrier, it does not have the excellent pore structure of mesoporous silica, and the transmission ability of dissolved oxygen and the target substance has decreased, resulting in a decrease in the removal rate of various indicators. At the same time, when polyvinyl alcohol is used as the carrier, although the particle size is large, it does not have the high-rigidity skeleton of mesoporous silica. When the sewage load suddenly increases, the impact resistance decreases significantly, and the stability has decreased significantly compared to Example 1.

[0101] Combined with Example 1 and Comparative Example 3, it can be seen that the particle size of the mud film in Comparative Example 3 is significantly larger than that in Example 1. The ability to remove COD, total nitrogen, and total phosphorus in sewage has decreased significantly compared to Example 1. After increasing the sewage load, the COD removal rate has decreased significantly, indicating that the stability and the ability to remove sewage impurities in Comparative Example 3 have decreased significantly compared to Example 1, and the particle size of the mud film is significantly larger than that in Example 1. The reason may be that in Comparative Example 3, no biological enhancement carrier was added. In the biological incubation system of the HJDL reaction tank of the active biological bactericide, aerobic sludge particles mainly supported by filamentous bacteria were gradually formed with flocculent sludge. The formed sludge particles are not restricted by the biological enhancement carrier, and the formed particle size is large. At the same time, without the protection of mesoporous silica, even if a good spatial structure is formed, when the sludge load increases, the filamentous bacteria do not have strong supporting force, and the impact resistance of the aerobic sludge particles decreases significantly, and the stability has decreased significantly compared to Example 1.

[0102] Combined with Example 1 and Examples 2-7, it can be seen that the particle size of the mud film in Examples 2-7 has no obvious change compared to Example 1. The ability to remove COD, total nitrogen, and total phosphorus in sewage has no obvious change compared to Example 1. After increasing the sewage load, the COD removal rate has no obvious change, indicating that the particle size, stability, and the ability to remove sewage impurities of the mud film in Examples 2-7 have no obvious change compared to Example 1. The reason may be that in Examples 2-7, only the dosage of the raw materials used in the preparation process of the biological enhancement carrier was changed on the basis of Example 1, and this change was within the required range, indicating that changing the dosage of the raw materials used within the required range has no obvious effect on the particle size, stability, and the ability to remove sewage impurities of the formed mud film.

[0103] Combined with Example 1, Example 8 and Example 9, it can be seen that the particle size of the mud film in Example 8 and Example 9 is larger than that in Example 1, and the ability to remove COD, total nitrogen and total phosphorus in sewage is lower than that in Example 1. After increasing the sewage load, the COD removal rate decreases. At the same time, compared with Example 9, the particle size of the mud film in Example 8 also increases, and after adding the sewage load, the decrease in the COD removal rate is more obvious. This shows that the stability and the ability to remove sewage impurities in Example 8 and Example 9 are lower than those in Example 1, and the decrease in Example 8 is more obvious than that in Example 9. The particle size of the mud film in Example 8 and Example 9 is larger than that in Example 1. The reason may be that the addition amount of polyvinyl alcohol is reduced in the process of preparing the bioaugmentation carrier in Example 8, while the addition amount of polyvinyl alcohol is increased in Example 9. When the number of polyvinyl alcohol connections on the surface of mesoporous silica decreases, the adsorption ability of the bioaugmentation carrier for the active biological agent weakens, and some microorganisms form mud film particles by themselves, resulting in an increase in the average particle size. At the same time, some microorganisms lack the protection of the mesoporous silica carrier, and the stability decreases. When the number of polyvinyl alcohol connections on the surface of mesoporous silica increases, on the one hand, the adsorption ability of polyvinyl alcohol for microorganisms has reached saturation, and further increasing it does not significantly improve the ability to remove impurities. On the other hand, after the content of polyvinyl alcohol increases, microorganisms mostly gather on the surface of mesoporous silica, and the number of microorganisms in the pores decreases relatively, resulting in an increase in particle size and a decrease in stability at the same time.

[0104] Combined with Example 1, Example 10 and Example 11, it can be seen that the particle size of the mud film in Example 10 is larger than that in Example 1. The ability of Example 10 and Example 11 to remove COD, total nitrogen, and total phosphorus in sewage is lower than that in Example 1. After increasing the sewage load, the COD removal rate decreases. At the same time, compared with Example 9, the particle size of the mud film in Example 10 increases. After adding the sewage load, the COD removal rate decreases significantly. This shows that the stability and the ability to remove sewage impurities of Example 10 and Example 11 are lower than those of Example 1, and the decrease in Example 10 is more obvious than that in Example 11. The particle size of the mud film in Example 10 is larger than that in Example 11. The reason may be that in the preparation process of mesoporous silica in Comparative Example 10, the addition amount of the composite template agent is reduced, resulting in a decrease in the number of pore channels in the formed mesoporous silica. Furthermore, in the process of forming the mud film particles, the content of microorganisms inside the particles decreases. Most microorganisms adhere to the surface of mesoporous silica or are free in the sewage, forming aerobic sludge particles with large particle sizes. The stability of the formed three-layer spatial structure decreases, resulting in a decrease in the sewage treatment ability, an increase in particle size, and a decrease in stability. In the preparation process of mesoporous silica in Example 11, the addition amount of the composite template agent is increased, resulting in an increase in the number of pore channels in the formed mesoporous silica. This leads to a decrease in the rigidity of mesoporous silica. When used as a bioaugmentation carrier, it is easily damaged by the composites brought by the sewage, and the overall stability decreases.

[0105] Combined with Example 1 and Example 12, it can be seen that the particle size of the mud film in Example 12 has no obvious change compared with that in Example 1. The ability to remove COD, total nitrogen, and total phosphorus in sewage is slightly improved compared with that in Example 1. After increasing the sewage load, the COD removal rate increases compared with that in Example 1. This shows that the particle size, stability, and the ability to remove sewage impurities of the mud film in Example 12 are slightly improved compared with those in Example 1. The reason may be that the bioaugmentation carrier used in Example 12 also adds water-soluble chitosan during the preparation process. Water-soluble chitosan has good biocompatibility and can form an interpenetrating network structure with polyvinyl alcohol, thereby enhancing the water-insolubility of polyvinyl alcohol and making polyvinyl alcohol not easily hydrolyzed in water. It can be seen from the increase in the COD removal rate after increasing the influent load that the COD removal rate does not decrease significantly, and the stability of the sludge particles is improved.

[0106] Combined with Example 1, Example 13 and Example 14, it can be seen that the particle size of the mud film in Example 13 is larger than that in Example 1. The ability of Example 12 and Example 13 to remove COD, total nitrogen, and total phosphorus from sewage is lower than that in Example 1. After increasing the sewage load, the COD removal rate decreases. At the same time, compared with Example 12, the particle size of the mud film in Example 13 also increases, indicating that the stability and the ability to remove sewage impurities in Example 12 and Example 13 are lower than those in Example 1. The particle size of the mud film in Example 13 is larger than that in Example 1. The reason may be that in Example 12, the addition amount of the active biological bactericide is reduced, resulting in no obvious change in the particle size of the formed mud film particles, but the ability to remove impurities decreases. In Example 13, the addition amount of the active biological bactericide is increased, and the number of active biological bactericides attached to the biological enhancement carrier has reached saturation. The extra bactericides form sludge particles in the sewage by themselves, resulting in an increase in the average particle size and a decrease in the overall stability.

[0107] Combined with Example 1 and Example 15, it can be seen that the particle size of the mud film in Example 14 has no obvious change compared with that in Example 1. The ability of Example 14 to remove COD, total nitrogen, and total phosphorus from sewage is lower than that in Example 1. After increasing the sewage load, the COD removal rate decreases, indicating that the stability and the ability to remove sewage impurities in Example 14 are lower than those in Example 1. The reason may be that in Example 14, no nutrient agent is added, and the active biological bactericides in the biological enhancement carrier do not get sufficient nutrients for further growth and reproduction, resulting in an increase in the mortality rate of microorganisms and a decrease in the overall stability, and the ability to remove various impurities in the sewage decreases.

[0108] This specific embodiment is only an explanation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A small-particle-size mud film particle, characterized in that, The small particle-size mud film particles include a biological enhancement carrier and an active biological agent with a mass ratio of 1:(0.2-0.4); the raw materials of the biological enhancement carrier include mesoporous silica and polyvinyl alcohol with a mass ratio of 1:(0.5-0.7); the particle size of the small particle-size mud film particles is 100-300 μm, and the particle size of the mesoporous silica is 20-50 nm; the raw materials of the biological enhancement carrier also include an amino-silane coupling agent and a basic catalyst, and the addition amount of the amino-silane coupling agent is 0.5-1.5% of the mass of the mesoporous silica; the addition amount of the basic catalyst is 0.2-0.4% of the mass of the mesoporous silica; The preparation process of the biological enhancement carrier is as follows: modification treatment of mesoporous silica, adding mesoporous silica to deionized water and dispersing it evenly, then adding an amino-silane coupling agent, stirring and reacting for 5-7 h under the water bath condition of 60-80 °C, and then obtaining modified mesoporous silica through centrifugation, washing and drying; preparation of the biological enhancement carrier, fully dissolving polyvinyl alcohol in deionized water, taking the modified mesoporous silica and dispersing it in deionized water, adding the polyvinyl alcohol solution and a basic catalyst, stirring and reacting under the water bath condition of 80-90 °C, and then obtaining the biological enhancement carrier through centrifugation, washing and drying.

2. The small-particle-size mud film particles according to claim 1, characterized in that The raw materials of the mesoporous silica include a composite template agent and tetraethyl orthosilicate with a mass ratio of (0.1-0.3):1; the composite template agent includes one or a combination of several of octadecyl dimethyl ammonium bromide, polyvinylpyrrolidone, and sodium dodecyl sulfate.

3. A small particle size mud film particle according to claim 2, wherein The preparation process of the mesoporous silica is as follows: adding the composite template agent to deionized water and stirring to completely dissolve it, then adding tetraethyl orthosilicate, stirring and reacting for 20-24 h under the water bath condition of 35-45 °C; after the reaction is completed, transferring it to a hydrothermal kettle for aging and crystallization for 24-26 h, putting the aged and crystallized product through drying and grinding into a muffle furnace, calcining at 500-600 °C for 5-7 h, and then obtaining mesoporous silica through grinding.

4. A small particle size mud film particle according to claim 1, characterized in that Water-soluble chitosan is also added during the preparation of the bioaugmentation carrier; the molecular weight of the water-soluble chitosan is 2.0×10 5 ~3.0×10 5 .

5. A small particle size mud film particle according to claim 1, wherein The active biological agent includes one or a combination of several of a composite COD bacterium, a composite denitrifying bacterium, a composite polyphosphorus-removing bacterium, a composite desulfurizing bacterium, a composite oil-removing bacterium, and a composite salt-tolerant bacterium.

6. A small particle size mud film particle according to claim 1, characterized in that, The biological enhancement carrier also includes a nutrient agent accounting for 3%-8% of the mass of the biological enhancement carrier; the nutrient agent includes one or a combination of several of glucose, sodium citrate, potassium phosphate, sodium chloride, peptone, and yeast extract.

7. A sewage treatment method for small particle size mud film particles according to any one of claims 1 to 6, characterized in that, It includes the following steps: Sewage enters the HJDL reaction tank through a grid. Combining with the biological incubation system in the HJDL reaction tank, the biological enhancement carrier and the active biological agent are put into the incubation system to form small particle-size mud film particles and remove impurities in the sewage; the water treated by the HJDL reaction tank enters the secondary sedimentation tank. The middle-layer sludge in the secondary sedimentation tank is re-discharged into the HJDL reaction tank for treatment, and the sewage with qualified water quality indicators after sedimentation treatment in the secondary sedimentation tank is discharged; the HJDL reaction tank also includes a stirring device and a reflux device.

Images