A quick start-up method for autotrophic denitrification process in a biological filter

Abstract

The present invention discloses a rapid startup method for an autotrophic denitrification process in a biofilter. The method comprises: (1) pre-inoculating activated sludge rich in denitrifying bacteria and sewage to be treated in the biofilter, and then cracking the sludge; (2) loading a carrier for culturing nitrifying bacteria into the cracked sludge of step (1), and carrying out biofilm culture of microorganisms required for the nitrification process; (3) when the ammonia nitrogen removal rate in the culture system of step (2) is more than 50%, loading a carrier for culturing anaerobic ammonia oxidizing bacteria, and carrying out biofilm culture of anaerobic ammonia oxidizing bacteria; (4) when the nitrite nitrogen removal rate in the culture system of step (3) reaches more than 50%, co-culturing of nitrifying bacteria and anaerobic ammonia oxidizing bacteria is carried out until the startup process is completed. The present invention first pre-treats the activated sludge system, and then loads the nitrifying bacteria carrier and the anaerobic ammonia oxidizing bacteria carrier in steps, accelerates the rapid biofilm formation of microorganisms with denitrification function, and realizes the rapid startup of the system.

Description

Technical Field

[0001] The invention belongs to the field of sewage treatment, and in particular relates to a rapid start-up method of an autotrophic denitrification process in a biological filter. Background Art

[0002] The CANON (completely autotrophic nitrogen removal overnitrite) process proposed at the end of the last century is a single-stage, fully biofilm autotrophic ammonia oxidation process. It does not require an external organic carbon source and ammonia oxidation remains at the nitrite stage, which can save aeration. It has attracted much attention as a new and ideal denitrification process. This process requires ammonia oxidizing bacteria and Anammox bacteria to coexist in the same reactor, and the two work synergistically to achieve denitrification. Studies have shown that the growth rate of anaerobic ammonia oxidizing bacteria is low (μ = 0.0027h -1 ), has a long generation cycle (10.6 days), and anaerobic ammonium oxidation (ANAMMOX) activity only manifests at an ANAMMOX cell concentration >1010–1011 cells / mL. The system's denitrification function typically takes several months to activate. Therefore, rapidly enriching ANAMMOX bacteria and rapidly initiating the CANON process has become a major bottleneck limiting its application.

[0003] CN201010136902.X discloses a method for rapidly starting a pre-denitrification biological aerated filter process. This method employs a method of initially establishing biofilm, then focusing on cultivating and acclimating nitrifying bacteria, and finally cultivating and acclimating denitrifying bacteria. This method reduces the acclimation steps and time, and lowers commissioning costs. Denitrifying bacteria can be rapidly cultivated within the anoxic denitrification biofilter of the pre-denitrification biological aerated filter process, and the effluent from the pre-denitrification biological aerated filter process can be commissioned to meet standards within 120 to 140 days. However, the technical commissioning period for this method exceeds three months.

[0004] Chinese patent CN201310084710.2 discloses a method for expanding and starting up a fully autotrophic denitrification process in a biological filter. First, a small amount of mature filter material of the fully autotrophic process biological filter is inoculated. The expanded startup method is adopted to first enrich anaerobic ammonia oxidizing bacteria through anaerobically culture, then culture aerobic ammonia oxidizing bacteria under oxygen-limited conditions and allow the anaerobic ammonia oxidizing bacteria to adapt to the aerobic environment, and finally aerobic aeration is used to start up the fully autotrophic denitrification process. Since the sludge in the fully autotrophic process already contains aerobic ammonia oxidizing bacteria and anaerobic ammonia oxidizing bacteria, there is no need to inoculate aerobic ammonia oxidizing bacteria when culturing aerobic ammonia oxidizing bacteria under oxygen-limited conditions, thus eliminating the need for an adaptation period for inoculating foreign ammonia oxidizing bacteria. After the anaerobic culture period is over, the fully autotrophic reactor can be started up more quickly with only a short oxygen-limited time. The present invention solves the problem of difficulty in starting up a fully autotrophic denitrification reactor, and the startup time is significantly shortened compared to the existing CANON startup process that uses other sludges as seed mud, but it still takes more than two months. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the present invention aims to provide a rapid startup method for an autotrophic denitrification process in a biofilter. The method of the present invention can accelerate the rapid biofilm formation of microorganisms with denitrification function, achieve rapid establishment of the denitrification function of the system, and realize rapid startup of the system.

[0006] The present invention provides a method for quickly starting an autotrophic denitrification process in a biological filter, comprising the following steps:

[0007] (1) Pre-inoculating activated sludge rich in denitrifying bacteria and wastewater to be treated in the biofilter, and then cracking the sludge;

[0008] (2) loading a carrier for cultivating nitrifying bacteria into the sludge system that has been cracked and treated in step (1) to carry out biofilm cultivation of microorganisms required for the nitrification process;

[0009] (3) When the ammonia nitrogen removal rate in the culture system of step (2) reaches 50% or more, preferably 60% to 70%, the carrier for culturing anaerobic ammonia-oxidizing bacteria is loaded to carry out biofilm culture of anaerobic ammonia-oxidizing bacteria;

[0010] (4) When the nitrite nitrogen removal rate in the culture system of step (3) reaches 50% or more, preferably 60% to 70%, the dissolved oxygen concentration is increased to co-cultivate nitrifying bacteria and anaerobic ammonia-oxidizing bacteria until the startup process is completed.

[0011] In the present invention, the carrier for culturing nitrifying bacteria is based on cross-linked chitosan embedded with calcium carbonate, on which heterotrophic bacteria are adsorbed and grown, wherein the heterotrophic bacteria account for 5% to 50% of the carrier mass, preferably 10% to 30%.

[0012] In the present invention, in the carrier for culturing anaerobic ammonia-oxidizing bacteria, heterotrophic bacteria account for 1% to 5% of the carrier mass, and polyethyleneimine accounts for 1% to 10% of the carrier mass.

[0013] In the present invention, in step (1), activated sludge rich in denitrifying bacteria is inoculated at a sludge concentration of 2000 to 3000 mg / L. The activated sludge to be inoculated can be excess sludge from a secondary sedimentation tank of a treatment plant that treats ammonia-containing wastewater. The excess sludge from the secondary sedimentation tank refers to sludge with a water content of less than 99%, preferably 80% to 90%, after gravity sedimentation in a sedimentation tank of a sewage treatment plant and the supernatant is discharged.

[0014] In the present invention, in step (1), the sludge is subjected to a disintegration treatment so that the extracellular polymeric substance is increased to no more than 60% by mass of protein, preferably 30% to 40% when disintegration is stopped. The disintegration treatment method adopts a method that can disintegrate the sludge floc structure and is non-toxic to organisms. The purpose of the disintegration treatment is mainly to encourage the sludge itself to secrete a large amount of extracellular polymeric substance and release it into the water, thereby significantly increasing the extracellular polymeric substance in the system, thereby facilitating the rapid biofilm formation of the bacteria in step (2). The disintegration treatment needs to strictly control the degree of disintegration, otherwise it will have an adverse effect on the sludge system.

[0015] In the present invention, in step (1), the cracking treatment can be carried out by excessive aeration. The excessive aeration method is to control the dissolved oxygen concentration to be greater than 5 mg / L, preferably 5 to 7 mg / L.

[0016] In the present invention, in step (2), the carrier for culturing nitrifying bacteria is added according to a content of 1 to 3 g / L after addition.

[0017] In the present invention, in step (2), the operating conditions are: dissolved oxygen 1-5 mg / L, preferably 2-4 mg / L, pH 7.5-8.5, temperature 25-40° C., and hydraulic retention time 6-12 h.

[0018] In the present invention, in step (3), the carrier for culturing anaerobic ammonia-oxidizing bacteria is added according to a content of 2 to 6 g / L after addition.

[0019] In the present invention, in step (3), the operating conditions are: dissolved oxygen 0.05-0.5 mg / L, preferably 0.1-0.3 mg / L, pH 7.5-8.5, temperature 25-40° C., and hydraulic retention time 6-12 h.

[0020] In the present invention, in step (4), the operating conditions are: dissolved oxygen 0.2-2.0 mg / L, preferably 0.5-1.5 mg / L, pH 7.5-8.5, temperature 25-40° C., and hydraulic retention time 12-24 h.

[0021] In the present invention, in step (4), when the ammonia nitrogen removal rate in the biological filter reaches more than 90%, the total nitrogen removal rate reaches more than 80%, and the total nitrogen removal load reaches 1.0 kg TN / (m 3 d) The above completes the system startup process.

[0022] In the present invention, the water quality of the sewage is: ammonia nitrogen concentration is 30-50 mg / L, nitrite nitrogen concentration is 30-50 mg / L, total nitrogen is 60-100 mg / L, and COD concentration is 50-150 mg / L.

[0023] In the present invention, the carrier for culturing nitrifying bacteria is prepared according to the following method: preparing a cross-linked chitosan carrier embedded with calcium carbonate; adding the cross-linked chitosan carrier to a heterotrophic bacteria culture system using an organic carbon source for adsorption growth, culturing until the late logarithmic growth stage, and removing the solid matter and drying it to obtain a double microcarrier.

[0024] In the present invention, in the preparation method of the carrier for culturing nitrifying bacteria, the cross-linked chitosan carrier embedded with calcium carbonate can be obtained by conventional preparation methods in the art. The cross-linking method can mainly adopt direct cross-linking, chemical modification during cross-linking, etc. The cross-linking agent used in the direct cross-linking method is at least one of epichlorohydrin, glutaraldehyde, formaldehyde, crown ethers and genipin, preferably genipin. Cross-linking is a cross-linking reaction between chitosan and cross-linking agent molecules, which changes the chitosan molecules from straight chains to a network structure. The physical properties of chitosan, such as the specific surface area and pore structure, can be improved by cross-linking, thereby effectively improving the stability of chitosan.

[0025] In the present invention, in the method for preparing a carrier for culturing nitrifying bacteria, the heterotrophic bacteria can be at least one of yeast, lactic acid bacteria, sulfate-reducing bacteria, and other heterotrophic bacteria that utilize organic carbon sources, preferably yeast. The yeast can be selected from at least one of Candida, Cryptococcus, Hansenula, Pichia, Rhodotorula, Torulopsis, or Trichosporon, preferably Candida tropicalis. The lactic acid bacteria can be selected from at least one of Lactobacillus, Bifidobacterium, and Lactococcus. The sulfate-reducing bacteria can be selected from at least one of Desulfomonas and Desulfuromyces.

[0026] In the method for preparing a carrier for culturing nitrifying bacteria of the present invention, the organic carbon source is determined based on the specific bacterial species selected and is generally a carbon-containing organic substance such as sugars, proteins, and organic acids conventionally used for culturing the selected heterotrophic bacteria, such as at least one of glucose, hexose, xylose, sucrose, and starch. The organic carbon source is added to the system at a mass concentration of 1 to 5 g / L.

[0027] In the method for preparing a carrier for culturing nitrifying bacteria of the present invention, the culture conditions for the heterotrophic bacteria are: a temperature of 20-38°C, preferably 20-30°C, a pH of 6.0-8.5, preferably 6.0-7.0; static fermentation or shaking culture, with stirring every 30-60 minutes for static fermentation and a shaking culture speed of 200-600 rpm for shaking culture. Cultivation is carried out until the late logarithmic growth stage, generally for 24-80 hours.

[0028] In the present invention, in the method for preparing the carrier for culturing nitrifying bacteria, the drying temperature is 25 to 50° C., and the drying time is 1 to 5 hours.

[0029] In the present invention, the carrier for culturing anaerobic ammonia-oxidizing bacteria is prepared according to the following method: heterotrophic bacteria that utilize an organic carbon source are cultured to the late logarithmic growth phase, and the bacterial cells are harvested; the bacterial cells are mixed with chitosan, and then cross-linked with calcium carbonate to prepare a cross-linked chitosan carrier; the cross-linked chitosan carrier is modified with polyethyleneimine to obtain a carrier for culturing anaerobic ammonia-oxidizing bacteria.

[0030] In the present invention, in the method for preparing a carrier for culturing anaerobic ammonia-oxidizing bacteria, the heterotrophic bacteria that utilize an organic carbon source are microorganisms that reproduce and grow using an organic carbon source under anaerobic or anoxic conditions, such as at least one of yeast, lactic acid bacteria, and sulfate-reducing bacteria. The yeast can be selected from at least one of Candida, Cryptococcus, Hansenula, Pichia pastoris, Rhodotorula, Torulopsis, or Trichosporon, preferably Candida tropicalis. The lactic acid bacteria can be selected from at least one of Lactobacillus, Bifidobacterium, and Lactococcus. The sulfate-reducing bacteria can be selected from at least one of Desulfomonas and Desulfuromyces.

[0031] In the present invention, in the method for preparing a carrier for culturing anaerobic ammonia-oxidizing bacteria, the organic carbon source is determined according to the selected heterotrophic bacteria, and is generally at least one of the carbon-containing organic substances such as sugars, proteins, organic acids, etc. used in the conventional cultivation of the selected heterotrophic bacteria, and specifically can be at least one of glucose, hexose, xylose, sucrose, starch, etc.

[0032] In the present invention, in the preparation method of the carrier for culturing anaerobic ammonia-oxidizing bacteria, the culture medium conventionally used in the art is selected for the culture of heterotrophic bacteria using an organic carbon source according to the bacteria. The culture conditions are: temperature 20-38°C, preferably 20-30°C, pH 6.0-8.5, preferably 6.0-7.0; static culture or shaking culture, static culture is stirred every 30-60 minutes, and the speed of shaking culture is 200-600r / min. Cultivate to the late logarithmic growth phase, generally culturing for 24-80 hours, and the bacterial cells can be harvested by filtration, centrifugation, etc. For example, the supernatant can be discarded and the bacterial cells can be retained by centrifugation at 10,000-15,000r / min.

[0033] In the present invention, in the preparation method of the carrier for culturing anaerobic ammonia-oxidizing bacteria, the bacterial cells and chitosan are mixed in a mass ratio of 1:1 to 1:3, and then cross-linked with calcium carbonate to prepare a cross-linked chitosan carrier. The preparation of the cross-linked chitosan carrier adopts the conventional preparation method in the field. The preparation method can adopt a direct cross-linking method, and the cross-linking agent used in the direct cross-linking method is at least one of epichlorohydrin, glutaraldehyde, formaldehyde, crown ethers, and genipin, preferably genipin. Cross-linking is a cross-linking reaction between chitosan and cross-linking agent molecules, which changes the chitosan molecules from straight chains to a network structure. The physical properties of chitosan, such as the specific surface area and pore structure, can be improved by cross-linking, thereby effectively improving the stability of chitosan. The specific preparation process is as follows: 2% chitosan is dissolved in 1% acetic acid solution (500 mL in total), chitosan is added at a mass volume ratio of 2% and acetic acid is added at a volume ratio of 1% to obtain a 500 mL mixed solution, the bacterial cells prepared in step (1) are added at a bacterial cell to chitosan mass ratio of 1:1 to 1:3, 10 g of CaCO3 nanoparticles are added, 5 times the volume of edible oil is added, 10 mL of Span-80 is added and stirred vigorously; then genipin is added to a final concentration of 20 mM in the aqueous phase, stirring is continued for 24 hours, the precipitate is separated by centrifugation, and the precipitate is washed several times with acetone, hot water, and cold water to remove the oil phase and impurities remaining on the surface. Finally, the product is dehydrated with acetone and air-dried at room temperature to obtain a cross-linked chitosan carrier with calcium carbonate as the core and bacterial cells and chitosan uniformly wrapped around it.

[0034] In the present invention, the method for preparing a carrier for culturing anaerobic ammonia-oxidizing bacteria comprises modifying a cross-linked chitosan carrier with polyethyleneimine. Specifically, the cross-linked chitosan carrier is immersed in an aqueous polyethyleneimine solution and dried. The polyethyleneimine solution has a mass fraction of 1% to 10% and the immersion time is 30 to 90 minutes. After immersion, the carrier is removed and dried at a temperature of 25 to 40°C for 1 to 5 hours. In the prepared carrier, the heterotrophic bacteria account for 1% to 5% of the carrier mass, and the polyethyleneimine accounts for 1% to 10% of the carrier mass.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] (1) The present invention starts the process by treating the activated sludge in the sewage treatment system and combining it with carriers for culturing different microorganisms. That is, by breaking the activated sludge to release a certain amount of extracellular polymers, and then adding the carrier, it helps to quickly form the autotrophic denitrification process of the biological filter process, quickly build the denitrification function of the system, and realize the rapid start-up of the treatment system.

[0037] (2) The carrier for culturing nitrifying bacteria used in the present invention is prepared from positively charged cross-linked chitosan and heterotrophic bacteria that utilize an organic carbon source. The positively charged cross-linked chitosan can effectively adsorb nitrifying bacteria onto the carrier for rapid adaptive growth, and the heterotrophic bacteria in the carrier can gradually release the binding sites, thereby increasing the activity and culture density of the nitrifying bacteria.

[0038] (3) The carrier used in the present invention for culturing anaerobic ammonia-oxidizing bacteria is prepared by the synergistic combination of three substances: chitosan, heterotrophic bacteria, and polyethyleneimine. Heterotrophic bacteria can improve the specific surface area and pore structure of chitosan, and the two play a synergistic role with each other. Moreover, during the growth of anaerobic ammonia-oxidizing bacteria, heterotrophic bacteria can degrade dead bacteria, leaving pores to provide a place for anaerobic ammonia-oxidizing bacteria, while degrading dead bacteria, releasing carbon dioxide gas, thereby improving mass transfer efficiency. The polyethyleneimine used can prevent the influence of oxygen on anaerobic ammonia-oxidizing bacteria, which is beneficial to improving the reproduction and growth rate of anaerobic ammonia-oxidizing bacteria. DETAILED DESCRIPTION

[0039] The following examples further illustrate the method and effects of the present invention. The examples are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operating processes, but the scope of protection of the present invention is not limited to the following examples.

[0040] The experimental methods in the following examples, unless otherwise specified, are all conventional methods in the art. The experimental materials used in the following examples, unless otherwise specified, can all be purchased from biochemical reagent stores.

[0041] In the embodiments of the present invention, the ammonia nitrogen concentration is determined by GB7478-87 "Water quality - Determination of ammonium - Distillation and titration method"; the protein content is determined by the LORRY method (Folin-phenol method).

[0042] Example 1

[0043] Preparation of carrier for culturing nitrifying bacteria.

[0044] First, 2% (w / v) chitosan was dissolved in 500 mL of 1% (v / v) acetic acid solution. 10 g of CaCO nanoparticles was added, along with 5 volumes of cooking oil and 10 mL of Span-80, and the mixture was stirred vigorously. Genipin was added to a final concentration of 20 mM in the aqueous phase. Stirring was continued for 24 hours, and the precipitate was separated by centrifugation. The microspheres were then washed several times with acetone, hot water, and cold water to remove any residual oil and impurities. Finally, the microspheres were dehydrated twice with acetone and air-dried at room temperature to obtain a slightly yellow powder, which is the chitosan microcarrier encapsulated with calcium carbonate.

[0045] The calcium carbonate-encapsulated chitosan microcarriers were added to a xylose-based culture system for Candida tropicalis to grow under adsorption conditions. The xylose concentration was 2 mg / L. The culture conditions were: 25°C, pH 6.0-7.0, and a shaking incubator at 200 rpm. After 48 hours of incubation, the solids were removed and dried at 40°C for 3 hours to produce a chitosan-based carrier A for culturing nitrifying bacteria. Testing revealed that heterotrophic bacteria accounted for 30% of the prepared carrier A.

[0046] Compared with the prepared nitrifying bacteria culture carrier A, other conditions remain unchanged, except that the culture system of Desulfuromonas using sucrose is used instead of the culture system of Candida tropicalis using xylose to prepare the nitrifying bacteria culture carrier B.

[0047] Compared with the prepared nitrifying bacteria culture carrier A, other conditions remained unchanged, except that: during the chitosan preparation process, genipin was replaced with 10 mL of 25% glutaraldehyde, 10 mL of 25% glutaraldehyde was added, stirring was continued for 2 hours, 5 g of sodium borohydride was added, and then reacted for 2 hours and then centrifuged to separate the precipitation, thereby preparing the nitrifying bacteria culture carrier C.

[0048] Compared with the prepared nitrifying bacteria culture carrier A, other conditions remain unchanged, except that: during the carrier preparation process, only chitosan is added without adding heterotrophic microorganisms, and the nitrifying bacteria culture carrier D is prepared.

[0049] Compared with the prepared nitrifying bacteria culture carrier A, other conditions remain unchanged, except that the culture system of tropical Candida is replaced by the culture system of heterotrophic denitrifying bacteria to prepare the nitrifying bacteria culture carrier E.

[0050] Table 1 Preparation of carriers for culturing nitrifying bacteria

[0051] Carrier model Chitosan microcarrier preparation Microbial species Carbon source type Proportion of heterotrophic bacteria A Join Kinipen Candida tropicalis Xylose 30％ B Join Kinipen Desulfuromonas sucrose 20％ C Add glutaraldehyde Candida tropicalis Xylose 26％ D Join Kinipen none none - E Join Kinipen Heterotrophic denitrifying bacteria Xylose 15％

[0052] Example 2

[0053] Preparation of carrier for culturing anaerobic ammonium oxidizing bacteria.

[0054] (1) Cultivate xylose-utilizing Candida tropicalis. The xylose concentration is 2 g / L. The culture conditions are: temperature 25°C, pH 6.0-7.0, shaker culture, and rotation speed 200 rpm. After 48 h of culture, the cells are centrifuged at 15,000 rpm, and the supernatant is discarded to retain the bacterial cells.

[0055] (2) chitosan was added at a mass volume ratio of 2% and acetic acid was added at a volume ratio of 1% to prepare 500 mL of a mixed solution, the bacterial cells prepared in step (1) were added at a bacterial cell to chitosan mass ratio of 1:2, and then 10 g of CaCO3 nanoparticles were added, 5 times the volume of edible oil was added, and 10 mL of Span-80 was added and stirred vigorously; genipin was added to a final concentration of 20 mM in the aqueous phase, and stirring was continued for 24 hours. The precipitate was separated by centrifugation and washed several times with acetone, hot water, and cold water to remove the oil phase and impurities remaining on the surface of the microspheres; finally, the microspheres were dehydrated with acetone twice, and the obtained product was dried at room temperature to obtain a cross-linked chitosan carrier with calcium carbonate as the core and bacterial cells and chitosan uniformly wrapped around it;

[0056] (3) The cross-linked chitosan carrier was immersed in a 5% (mass fraction) aqueous solution of polyethyleneimine for 60 min, then removed and dried at 35°C for 3 h to obtain carrier I for culturing anaerobic ammonia-oxidizing bacteria. Testing showed that heterotrophic bacteria accounted for 2.5% of the carrier mass, and polyethyleneimine accounted for 5.5% of the carrier mass.

[0057] Compared with carrier I for culturing anaerobic ammonia-oxidizing bacteria, other conditions remain unchanged, except that: the bacterial cells prepared in step (1) are added according to a mass ratio of bacterial cells to chitosan of 1:1, and the cross-linked chitosan carrier is immersed in a polyethyleneimine aqueous solution with a mass fraction of 2% to prepare carrier II for culturing anaerobic ammonia-oxidizing bacteria.

[0058] Compared with carrier I for culturing anaerobic ammonia oxidizing bacteria, other conditions remain unchanged, but the difference is that lactobacillus that utilizes glucose is used instead of tropical Candida that utilizes xylose to prepare carrier III for culturing anaerobic ammonia oxidizing bacteria.

[0059] Compared with carrier I for culturing anaerobic ammonium oxidizing bacteria, other conditions remain unchanged, except that the cross-linked chitosan carrier is not modified with polyethyleneimine to prepare carrier IV for culturing anaerobic ammonium oxidizing bacteria.

[0060] Compared with carrier I for culturing anaerobic ammonia oxidizing bacteria, other conditions remain unchanged, but the difference is that only chitosan is used in the preparation of the carrier without adding bacterial cells, thus preparing carrier V for culturing anaerobic ammonia oxidizing bacteria.

[0061] Table 1 Preparation of carriers for culturing anaerobic ammonium oxidizing bacteria

[0062] Carrier model Microbial species and carbon sources Mass ratio of bacterial cells to chitosan Mass fraction of polyethyleneimine Ⅰ Candida tropicalis, Xylose 1:2 5％ Ⅱ Candida tropicalis, Xylose 1:1 2％ Ⅲ Lactobacillus, glucose 1:2 5％ Ⅳ Candida tropicalis, Xylose 1:2 none Ⅴ Candida tropicalis, Xylose Only chitosan 5％

[0063] Example 3

[0064] The laboratory built a 50L biological aeration filter. The biofilter was pre-inoculated with activated sludge rich in denitrifying bacteria and the wastewater to be treated at a sludge concentration of 2000mg / L. The sludge was then broken down by controlling the dissolved oxygen concentration to around 6mg / L, until the extracellular polymeric substances (ECPs) reached 30% by weight of protein. The wastewater quality was as follows: ammonia nitrogen concentration of 30-50mg / L, nitrite nitrogen concentration of 30-50mg / L, total nitrogen concentration of 60-100mg / L, and COD concentration of 50-150mg / L.

[0065] The carrier A for culturing nitrifying bacteria of Example 1 was loaded into the filter at a content of 2 g / L for biofilm culture of the microorganisms required for the nitrification process; the culture conditions were: dissolved oxygen 2-4 mg / L, pH 7.5-7.8, temperature 28-30°C, continuous water inlet, and a hydraulic retention time of 8 h. When the ammonia nitrogen removal rate in the culture system reached 65%, the carrier I for culturing anaerobic ammonia oxidizing bacteria of Example 2 was loaded into the filter at a content of 4 g / L after addition for biofilm culture of anaerobic ammonia oxidizing bacteria; the culture conditions were: dissolved oxygen 0.1-0.3 mg / L, pH 7.5-8.5, temperature 28-30°C, continuous water inlet, and a hydraulic retention time of 8 h. When the nitrite nitrogen removal rate in the culture system reached 65%, the dissolved oxygen concentration was increased to 0.5-1.5 mg / L for co-cultivation of nitrifying bacteria and anaerobic ammonia oxidizing bacteria, and the hydraulic retention time was 18 h, with other conditions remaining unchanged.

[0066] When the ammonia nitrogen removal rate in the biofilter reaches 96% and the total nitrogen removal rate reaches 86%, the total nitrogen removal load reaches 1.2kgTN / (m 3 d) Complete the system startup process, which takes 25 days.

[0067] Example 4

[0068] The laboratory built a 50L biological aeration filter. The biofilter was pre-inoculated with activated sludge rich in denitrifying bacteria and the wastewater to be treated at a sludge concentration of 2000mg / L. The sludge was then broken down by controlling the dissolved oxygen concentration to around 6mg / L, until the extracellular polymeric substances (ECPs) reached 30% by weight of protein. The wastewater quality was as follows: ammonia nitrogen concentration of 30-50mg / L, nitrite nitrogen concentration of 30-50mg / L, total nitrogen concentration of 60-100mg / L, and COD concentration of 50-150mg / L.

[0069] The carrier B for culturing nitrifying bacteria of Example 1 was loaded into the filter at a content of 2 g / L for biofilm culture of the microorganisms required for the nitrification process; the culture conditions were: dissolved oxygen 2-4 mg / L, pH 7.5-7.8, temperature 28-30°C, continuous water inlet, and a hydraulic retention time of 8 h. When the ammonia nitrogen removal rate in the culture system reached 65%, the carrier II for culturing anaerobic ammonia oxidizing bacteria of Example 2 was loaded into the filter at a content of 4 g / L after addition for biofilm culture of anaerobic ammonia oxidizing bacteria; the culture conditions were: dissolved oxygen 0.1-0.3 mg / L, pH 7.5-8.5, temperature 28-30°C, continuous water inlet, and a hydraulic retention time of 8 h. When the nitrite nitrogen removal rate in the culture system reached 65%, the dissolved oxygen concentration was increased to 0.5-1.5 mg / L for co-cultivation of nitrifying bacteria and anaerobic ammonia oxidizing bacteria, and the hydraulic retention time was 18 h, with other conditions remaining unchanged.

[0070] When the ammonia nitrogen removal rate in the biofilter reaches 93%, the total nitrogen removal rate reaches 84%, and the total nitrogen removal load reaches 1.1kgTN / (m 3 d) The system startup process is completed, and the startup time is 26 days.

[0071] Example 5

[0072] The laboratory built a 50L biological aeration filter. The biofilter was pre-inoculated with activated sludge rich in denitrifying bacteria and the wastewater to be treated at a sludge concentration of 3000mg / L. The sludge was then broken down by controlling the dissolved oxygen concentration to around 6mg / L, stopping when the extracellular polymeric substances (ECPs) reached 40% by weight of protein. The wastewater quality was as follows: ammonia nitrogen concentration of 30-50mg / L, nitrite nitrogen concentration of 30-50mg / L, total nitrogen concentration of 60-100mg / L, and COD concentration of 50-150mg / L.

[0073] The carrier C for culturing nitrifying bacteria in Example 1 was loaded into the filter at a content of 2 g / L for biofilm culture of the microorganisms required for the nitrification process; the culture conditions were: dissolved oxygen 2-4 mg / L, pH 7.5-7.8, temperature 28-30°C, continuous water inflow, and a hydraulic retention time of 8 h. When the ammonia nitrogen removal rate in the culture system reached 65%, the carrier III for culturing anaerobic ammonia oxidizing bacteria in Example 2 was loaded into the filter at a content of 4 g / L after addition for biofilm culture of anaerobic ammonia oxidizing bacteria; the culture conditions were: dissolved oxygen 0.1-0.3 mg / L, pH 7.5-8.5, temperature 28-30°C, continuous water inflow, and a hydraulic retention time of 8 h. When the nitrite nitrogen removal rate in the culture system reached 65%, the dissolved oxygen concentration was increased to 0.5-1.5 mg / L for co-cultivation of nitrifying bacteria and anaerobic ammonia oxidizing bacteria, with a hydraulic retention time of 18 h, and other conditions remained unchanged.

[0074] When the ammonia nitrogen removal rate in the biofilter reaches 92% and the total nitrogen removal rate reaches 85%, the total nitrogen removal load reaches 1.1kgTN / (m 3 d) The system startup process is completed, and the startup time is 27 days.

[0075] Example 6

[0076] The laboratory built a 50L biological aeration filter. The biofilter was pre-inoculated with activated sludge rich in denitrifying bacteria and the wastewater to be treated at a sludge concentration of 3000mg / L. The sludge was then broken down by controlling the dissolved oxygen concentration to around 6mg / L, stopping when the extracellular polymeric substances (ECPs) reached 40% by weight of protein. The wastewater quality was as follows: ammonia nitrogen concentration of 30-50mg / L, nitrite nitrogen concentration of 30-50mg / L, total nitrogen concentration of 60-100mg / L, and COD concentration of 50-150mg / L.

[0077] The carrier A for culturing nitrifying bacteria of Example 1 is loaded into the filter according to a content of 1g / L for biofilm culture of the microorganisms required for the nitrification process; the culture conditions are: dissolved oxygen 2-4mg / L, pH 7.5-7.8, temperature 28-30°C, continuous water inlet, and hydraulic retention time of 6h. When the ammonia nitrogen removal rate in the culture system reaches 60%, the carrier I for culturing anaerobic ammonia oxidizing bacteria of Example 2 is loaded into the filter according to the added content of 2g / L for biofilm culture of anaerobic ammonia oxidizing bacteria; the culture conditions are: dissolved oxygen 0.1-0.3mg / L, pH 7.5-8.5, temperature 28-30°C, continuous water inlet, and hydraulic retention time of 6h. When the nitrite nitrogen removal rate in the culture system reaches 60%, the dissolved oxygen concentration is increased to 0.5-1.5mg / L for co-cultivation of nitrifying bacteria and anaerobic ammonia oxidizing bacteria, and the hydraulic retention time is 12h, while other conditions remain unchanged.

[0078] When the ammonia nitrogen removal rate in the biofilter reaches 94%, the total nitrogen removal rate reaches 83%, and the total nitrogen removal load reaches 1.1kgTN / (m 3 d) Complete the system startup process, which takes 25 days.

[0079] Example 7

[0080] The laboratory built a 50L effective volume aerated biological filter. The biofilter was pre-inoculated with activated sludge rich in denitrifying bacteria and the wastewater to be treated at a sludge concentration of 2000mg / L. The sludge was then broken down by controlling the dissolved oxygen concentration to around 6mg / L, until the extracellular polymeric substances (ECPs) reached 25% by weight of protein. The wastewater quality to be treated was: ammonia nitrogen concentration of 30-50mg / L, nitrite nitrogen concentration of 30-50mg / L, total nitrogen concentration of 60-100mg / L, and COD concentration of 50-150mg / L.

[0081] The carrier A for culturing nitrifying bacteria of Example 1 was loaded into the filter at a content of 3 g / L for biofilm culture of the microorganisms required for the nitrification process; the culture conditions were: dissolved oxygen 2-4 mg / L, pH 7.5-7.8, temperature 28-30°C, continuous water inlet, and a hydraulic retention time of 12 h. When the ammonia nitrogen removal rate in the culture system reached 70%, the carrier I for culturing anaerobic ammonia oxidizing bacteria of Example 2 was loaded into the filter at a content of 6 g / L after addition for biofilm culture of anaerobic ammonia oxidizing bacteria; the culture conditions were: dissolved oxygen 0.1-0.3 mg / L, pH 7.5-8.5, temperature 28-30°C, continuous water inlet, and a hydraulic retention time of 12 h. When the nitrite nitrogen removal rate in the culture system reached 70%, the dissolved oxygen concentration was increased to 0.5-1.5 mg / L for co-cultivation of nitrifying bacteria and anaerobic ammonia oxidizing bacteria, and the hydraulic retention time was 24 h, with other conditions remaining unchanged.

[0082] When the ammonia nitrogen removal rate in the biofilter reaches 95% and the total nitrogen removal rate reaches 85%, the total nitrogen removal load reaches 1.0 kg TN / (m 3 d) Complete the system startup process, which takes 25 days.

[0083] Example 8

[0084] The startup process and conditions were the same as those in Example 3, except that the activated sludge decomposition treatment control system was stopped after the protein content increased to 20%. 35 days after the system was started, the ammonia nitrogen removal rate in the biofilter reached 92%, the total nitrogen removal rate reached 83%, and the total nitrogen removal load reached 1.0 kg TN / (m 3 d) Complete the system startup process.

[0085] Comparative Example 1

[0086] The startup process and conditions were the same as those in Example 3, except that the carrier D for culturing nitrifying bacteria in Example 1 was used. 49 days after the system was started, the ammonia nitrogen removal rate in the biofilter reached 91%, the total nitrogen removal rate reached 82%, and the total nitrogen removal load reached 1.0 kg TN / (m 3 d), the startup time is longer.

[0087] Comparative Example 2

[0088] The startup process and conditions were the same as those in Example 3, except that the carrier E for culturing nitrifying bacteria in Example 1 was used. 50 days after the system was started, the ammonia nitrogen removal rate in the biofilter reached 92%, the total nitrogen removal rate reached 84%, and the total nitrogen removal load reached 1.05 kg TN / (m 3 d), the startup time is longer.

[0089] Comparative Example 3

[0090] The startup process and conditions were the same as those in Example 3, except that the anaerobic ammonia oxidizing bacteria carrier IV of Example 1 was used. 51 days after the system was started, the ammonia nitrogen removal rate in the biofilter reached 94%, the total nitrogen removal rate reached 83%, and the total nitrogen removal load reached 1.0 kg TN / (m 3 d), the startup time is longer.

[0091] Comparative Example 4

[0092] The startup process and conditions were the same as those in Example 3, except that the anaerobic ammonia oxidizing bacteria carrier V of Example 1 was used. 50 days after the system was started, the ammonia nitrogen removal rate in the biofilter reached 92%, the total nitrogen removal rate reached 82%, and the total nitrogen removal load reached 1.0 kg TN / (m 3 d), the startup time is longer.

[0093] Comparative Example 5

[0094] The startup process and conditions were the same as those in Example 3, except that the carrier E for culturing nitrifying bacteria and the carrier V for culturing anaerobic ammonia oxidizing bacteria in Example 1 were used. 64 days after the system was started, the ammonia nitrogen removal rate in the biofilter reached 91%, the total nitrogen removal rate reached 81%, and the total nitrogen removal load reached 1.0 kg TN / (m 3 d), the startup time is longer.

[0095] Comparative Example 6

[0096] The startup process and conditions were the same as in Example 3, except that the sludge was not cracked before the carrier was added. 56 days after the system was started, the ammonia nitrogen removal rate in the biofilter reached 93%, the total nitrogen removal rate reached 81%, and the total nitrogen removal load reached 1.0 kg TN / (m 3 d), the startup time is longer.

Claims

1. A method for quickly starting a biofilter autotrophic denitrification process, comprising the following steps: (1) Pre-inoculate activated sludge rich in denitrifying bacteria and wastewater to be treated in the biofilter, and then perform decomposition treatment on the sludge; (2) loading a carrier for cultivating nitrifying bacteria into the sludge system that has been cracked and treated in step (1) to carry out biofilm cultivation of microorganisms required for the nitrification process; (3) When the ammonia nitrogen removal rate in the culture system of step (2) reaches more than 50%, the carrier for culturing anaerobic ammonia oxidizing bacteria is loaded to carry out biofilm culture of anaerobic ammonia oxidizing bacteria; (4) When the nitrite nitrogen removal rate in the culture system of step (3) reaches more than 50%, the dissolved oxygen concentration is increased to co-cultivate nitrifying bacteria and anaerobic ammonia-oxidizing bacteria until the startup process is completed; The carrier for culturing nitrifying bacteria is based on cross-linked chitosan embedded with calcium carbonate, on which heterotrophic bacteria are adsorbed and grown, wherein the heterotrophic bacteria account for 5% to 50% of the carrier mass; The carrier for culturing anaerobic ammonia-oxidizing bacteria is prepared according to the following method: heterotrophic bacteria that utilize an organic carbon source are cultured to the late logarithmic growth phase, and bacterial cells are harvested; the bacterial cells are mixed with chitosan, and then cross-linked with calcium carbonate to prepare a cross-linked chitosan carrier; the cross-linked chitosan carrier is modified with polyethyleneimine to obtain a carrier for culturing anaerobic ammonia-oxidizing bacteria; The carrier for culturing nitrifying bacteria is prepared according to the following method: preparing a cross-linked chitosan carrier embedded with calcium carbonate; adding the cross-linked chitosan carrier to a heterotrophic bacteria culture system using an organic carbon source for adsorption growth, culturing until the late logarithmic growth stage, removing the solid matter and drying it to obtain the carrier for culturing nitrifying bacteria; The heterotrophic bacteria is at least one of yeast, lactic acid bacteria and sulfate-reducing bacteria.

2. The method according to claim 1, characterized in that In step (3), when the ammonia nitrogen removal rate in the culture system of step (2) reaches 60% to 70%, the carrier for culturing anaerobic ammonia oxidizing bacteria is loaded and biofilm culture of anaerobic ammonia oxidizing bacteria is carried out.

3. The method according to claim 1, characterized in that In step (4), when the nitrite nitrogen removal rate in the culture system of step (3) reaches 60% to 70%, the dissolved oxygen concentration is increased to co-cultivate nitrifying bacteria and anaerobic ammonia-oxidizing bacteria until the startup process is completed.

4. The method according to claim 1, wherein The carrier for culturing nitrifying bacteria is based on cross-linked chitosan embedded with calcium carbonate, on which heterotrophic bacteria are adsorbed and grown, wherein the heterotrophic bacteria account for 10% to 30% of the carrier mass; and / or, in the carrier for culturing anaerobic ammonia-oxidizing bacteria, the heterotrophic bacteria account for 1% to 5% of the carrier mass, and polyethyleneimine accounts for 1% to 10% of the carrier mass.

5. The method according to claim 1, wherein In step (1), activated sludge rich in denitrifying bacteria is inoculated at a sludge concentration of 2000-3000 mg / L.

6. The method according to claim 1, wherein In step (1), the sludge is subjected to a cracking treatment so that the extracellular polymer content is increased to no more than 60% based on the mass content of protein, and the cracking is stopped.

7. The method according to claim 6, characterized in that In step (1), the sludge is subjected to a cracking treatment so that the extracellular polymer content increases to 30% to 40% based on the mass content of protein, and the cracking is stopped.

8. The method according to claim 1, characterized in that In step (1), the cracking treatment method is excessive aeration.

9. The method according to claim 1, characterized in that In step (2), the carrier for culturing nitrifying bacteria is added at a content of 1 to 3 g / L after addition; and / or, in step (3), the carrier for culturing anaerobic ammonia oxidizing bacteria is added at a content of 2 to 6 g / L after addition.

10. The method according to claim 1, characterized in that In step (2), the operating conditions are: dissolved oxygen 1~5 mg / L, pH value 7.5~8.5, temperature 25~40℃, and hydraulic retention time 6~12h.

11. The method according to claim 10, characterized in that In step (2), the operating conditions are: dissolved oxygen 2~4 mg / L.

12. The method according to claim 1, characterized in that In step (3), the operating conditions are: dissolved oxygen 0.05~0.5 mg / L, pH value 7.5~8.5, temperature 25~40℃, and hydraulic retention time 6~12h.

13. The method according to claim 12, characterized in that In step (3), the operating conditions are: dissolved oxygen 0.1~0.3 mg / L.

14. The method according to claim 1, characterized in that In step (4), the operating conditions are: dissolved oxygen 0.2~2.0 mg / L, pH value 7.5~8.5, temperature 25~40℃, and hydraulic retention time 12~24h.

15. The method according to claim 14, characterized in that In step (4), the operating conditions are: dissolved oxygen 0.5~1.5 mg / L.

16. The method according to claim 1, wherein In step (4), when the ammonia nitrogen removal rate in the biological filter reaches more than 90%, the total nitrogen removal rate reaches more than 80%, and the total nitrogen removal load reaches 1.0 kg TN / (m 3 d) The above completes the system startup process.

17. The method according to claim 1, wherein The water quality of the sewage is: ammonia nitrogen concentration is 30~50mg / L, nitrite nitrogen concentration is 30~50mg / L, total nitrogen is 60~100mg / L, and COD concentration is 50~150mg / L.

18. The method according to claim 1, wherein The yeast is selected from at least one of Candida, Cryptococcus, Hansenula, Pichia, Rhodotorula, Torulopsis or Trichosporon; the lactic acid bacteria is selected from at least one of Lactobacillus, Bifidobacterium and Lactococcus; the sulfate-reducing bacteria is selected from at least one of Desulfomonas and Desulfuromyces.

19. The method according to claim 18, characterized in that The heterotrophic bacteria is yeast; the yeast is Candida tropicalis.

20. The method according to claim 1, wherein In the preparation method of the carrier for culturing anaerobic ammonia-oxidizing bacteria, the culture conditions are: temperature 20-38°C, pH 6.0-8.5; static culture or shaking culture, static culture is stirred every 30-60 minutes, and the shaking culture speed is 200-600 r / min.

21. The method according to claim 20, characterized in that In the method for preparing a carrier for culturing anaerobic ammonia-oxidizing bacteria, the culture conditions are: temperature 20-30° C., pH 6.0-7.

0.

22. The method according to claim 1, wherein In the method for preparing a carrier for culturing anaerobic ammonia-oxidizing bacteria, bacterial cells and chitosan are mixed in a mass ratio of 1:1 to 1:3, and then cross-linked with calcium carbonate to prepare a cross-linked chitosan carrier.

23. The method according to claim 1, wherein In the preparation method of the carrier for culturing anaerobic ammonia-oxidizing bacteria, polyethyleneimine is used to modify the cross-linked chitosan carrier. Specifically, the cross-linked chitosan carrier is immersed in a polyethyleneimine aqueous solution and then dried to obtain the carrier; wherein the mass fraction of the polyethyleneimine aqueous solution is 1% to 10%, the immersion time is 30 to 90 minutes, the drying temperature is 25 to 40°C, and the drying time is 1 to 5 hours.