A method for quickly starting the denitrification function of an A / O system

Abstract

The present invention discloses a method for quickly starting the denitrification function of an A / O system. The method comprises: (1) pre-inoculating activated sludge rich in denitrifying bacteria in an anaerobic tank (tank A) and an aerobic tank (tank O), and then cracking the sludge respectively; (2) loading a carrier for cultivating anaerobic ammonia-oxidizing bacteria into the tank A that has been cracked in step (1), and loading a carrier for cultivating nitrifying bacteria into the tank O that has been cracked in step (1), and then supplementing ammonia-containing sewage to start the system to continuously feed water and run until the system is started. The present invention first pre-treats the activated sludge inoculated in tanks A and O, and then adds anaerobic ammonia-oxidizing bacteria carriers and nitrifying bacteria carriers respectively, and then feeds water and runs, which can accelerate the rapid biofilm formation of microorganisms with denitrification function, promote the rapid construction of the system's denitrification function, and achieve rapid startup of the system.

Description

Technical Field

[0001] The invention belongs to the field of sewage treatment, and in particular relates to a method for quickly starting the denitrification function of an A / O system. Background Art

[0002] Most existing sewage biological treatment systems focus on removing organic pollutants. The functional microorganisms responsible for removing nitrogen-containing pollutants need to be strengthened to achieve denitrification. In particular, the startup of the system's denitrification function generally takes several months.

[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. It can rapidly cultivate denitrifying bacteria in the anoxic denitrification biofilter of the pre-denitrification biological aerated filter process, and can achieve process effluent compliance within 120 to 140 days. However, the commissioning period for this method exceeds three months.

[0004] CN201210130655.1 discloses a rapid startup method for treating ammonia-containing wastewater using an A / O process. This method first places an inoculum into a bioreactor. The inoculum is a mixture of enriched nitrifying bacteria and a nitrite-type denitrifying agent, or aerobic activated sludge from a sewage treatment plant. System startup is performed using both intermittent and continuous water inflow. Nitrifying bacteria are added during water inflow, while denitrifying agents are added during continuous water inflow. This method offers advantages such as relaxed startup requirements, rapid startup, and the ability to treat high-concentration ammonia-containing wastewater. This method primarily utilizes the addition of enriched nitrifying bacteria and a liquid agent. The liquid agent has relatively high activity and readily exerts its denitrification function upon addition. However, there is still a risk of loss of the liquid agent during use. Summary of the Invention

[0005] In response to the shortcomings of the prior art, the present invention aims to provide a method for rapidly starting the denitrification function of an A / O system. The method of the present invention can accelerate the rapid biofilm formation of denitrifying microorganisms, promote the rapid establishment of the system's denitrification function, and achieve rapid system startup.

[0006] The present invention provides a method for quickly starting the denitrification function of an A / O system, comprising the following steps:

[0007] (1) Activated sludge rich in denitrifying bacteria is pre-inoculated in the anaerobic tank (tank A) and the aerobic tank (tank O), and then the sludge is cracked and treated respectively;

[0008] (2) Loading a carrier for culturing anaerobic ammonia-oxidizing bacteria into the A pool that has been cracked in step (1), loading a carrier for culturing nitrifying bacteria into the O pool that has been cracked in step (1), and then adding ammonia-containing sewage to start the system to continuously feed water until the system startup is completed.

[0009] 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%.

[0010] 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.

[0011] In the present invention, in step (1), activated sludge rich in denitrifying bacteria is inoculated into tanks A and O at a sludge concentration of 3000 to 4000 mg / L. The activated sludge 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, after the supernatant is discharged.

[0012] In the present invention, in step (1), the sludge is subjected to a cracking treatment so that the extracellular polymers are increased to no more than 60% by mass of protein, preferably 30% to 40%, and then the process is switched to conventional operation. The cracking treatment method adopts a method that can break the sludge floc structure and is non-toxic to organisms. The purpose of the cracking treatment is mainly to encourage the sludge itself to secrete a large amount of extracellular polymers and release them into the water, thereby significantly increasing the extracellular polymers in the system, thereby facilitating the rapid biofilm formation of the bacteria in step (2). The degree of cracking needs to be strictly controlled during the cracking treatment, otherwise it will have an adverse effect on the sludge system.

[0013] In the present invention, in step (1), the cracking treatment method of pool A is strong stirring; the cracking treatment method of pool O is excessive aeration. The strong stirring method is to increase the stirring intensity by 0.5 to 1.0 times compared with the conventional operation; the excessive aeration method is to control the dissolved oxygen concentration to be above 5 mg / L, preferably 5 to 6 mg / L.

[0014] In the present invention, in step (2), the loading amount of the carrier for culturing nitrifying bacteria and the carrier for culturing anaerobic ammonia oxidizing bacteria are independently added according to the content in the system of 1 to 5 g / L.

[0015] In the present invention, in step (2), when the system is started by adding ammonia-containing wastewater, the denitrification function of tank A is activated, and the nitrification function of tank O is activated. The denitrification function is activated by stirring; the nitrification function is activated by aeration, specifically by turning on the aeration fan.

[0016] In the present invention, in step (2), the operating conditions of pool A are: dissolved oxygen 0.1-1.0 mg / L, preferably 0.2-0.5 mg / L, pH 7.5-8.5, and temperature 25-40°C; the operating conditions of pool O are: dissolved oxygen 1-5 mg / L, preferably 2-4 mg / L, pH 7.5-8.5, and temperature 25-40°C.

[0017] In the present invention, in step (2), when the ammonia nitrogen concentration of the effluent in the system is less than 5 mg / L and the total nitrogen concentration is less than 25 mg / L, the system startup is completed.

[0018] In the present invention, in step (2), both Pool A and Pool O have their own secondary sedimentation tanks. During operation, the mud-water mixture in Pool A is separated in the secondary sedimentation tank, the supernatant enters Pool O, and the bottom sediment returns to Pool A. The mud-water mixture in Pool O is separated in the secondary sedimentation tank, part of the supernatant is returned to Pool A, part is discharged, and the bottom sediment returns to Pool O.

[0019] In the present invention, in step (2), the water quality can be regulated by adjusting the reflux ratio of the supernatant in the O tank during the startup process.

[0020] In the present invention, the water quality of the ammonia-containing sewage is: an ammonia nitrogen concentration of 200-300 mg / L, a total nitrogen concentration of 200-400 mg / L, and a COD concentration of 300-400 mg / L.

[0021] 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, removing the solid matter and drying it to obtain the carrier for culturing nitrifying bacteria.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] (1) The present invention starts the process by treating the activated sludge in the sewage treatment system and combining it with carriers for cultivating 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 build the denitrification function of the system and realize the rapid startup of the A / O treatment system.

[0035] (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.

[0036] (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

[0037] 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.

[0038] 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.

[0039] 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).

[0040] Example 1

[0041] Preparation of carrier for culturing nitrifying bacteria.

[0042] 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.

[0043] 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.

[0044] Compared with the preparation method of carrier A, other conditions remain unchanged, except that the culture system of Desulfuromonas using sucrose is replaced by the culture system of Candida tropicalis using xylose to prepare carrier B for culturing nitrifying bacteria.

[0045] Compared with the preparation method of carrier A, other conditions remain unchanged, except that: during the preparation of chitosan, genipin is replaced with 10 mL of 25% glutaraldehyde, 10 mL of 25% glutaraldehyde is added, stirring is continued for 2 hours, 5 g of sodium borohydride is added, and the reaction is carried out for 2 hours, and then centrifugation and precipitation are separated to prepare carrier C for culturing nitrifying bacteria.

[0046] Compared with the preparation method of carrier A, other conditions remain unchanged, except that: during the carrier preparation process, only chitosan is added without adding heterotrophic microorganisms, and carrier D for culturing nitrifying bacteria is prepared.

[0047] Compared with the preparation method of carrier A, other conditions remain unchanged, except that a culture system of heterotrophic denitrifying bacteria is used instead of a culture system of tropical Candida to prepare carrier E for culturing nitrifying bacteria.

[0048] Table 1 Preparation of carriers for culturing nitrifying bacteria

[0049] 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％

[0050] Example 2

[0051] Preparation of carrier for culturing anaerobic ammonium oxidizing bacteria.

[0052] (1) Cultivate xylose-utilizing Candida tropicalis. The xylose concentration was 2 g / L. The culture conditions were: temperature 25°C, pH 6.0-7.0, incubation on a shaker at 200 rpm. After 48 h of culture, the cells were centrifuged at 15,000 rpm, and the supernatant was discarded, retaining the bacterial cells.

[0053] (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 mass ratio of bacterial cells to chitosan 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 the mixture was stirred continuously 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 mixture was dehydrated with acetone twice, and the resulting 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.

[0054] (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.

[0055] Compared with the preparation method of carrier I, 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.

[0056] Compared with the preparation method of carrier I, other conditions remain unchanged, except that lactobacillus that utilizes glucose is used instead of tropical Candida that utilizes xylose to prepare carrier III for culturing anaerobic ammonia oxidizing bacteria.

[0057] Compared with the preparation method of carrier I, other conditions remain unchanged, except that: polyethyleneimine is not used to modify the cross-linked chitosan carrier, and carrier IV for culturing anaerobic ammonia oxidizing bacteria is prepared.

[0058] Compared with the preparation method of carrier I, other conditions remain unchanged, except that only chitosan is used in the preparation of the carrier without adding bacterial cells, and the carrier V for culturing anaerobic ammonia oxidizing bacteria is prepared.

[0059] Table 1 Preparation of carriers for culturing anaerobic ammonium oxidizing bacteria

[0060] 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％

[0061] Example 3

[0062] The laboratory constructed a self-constructed A / O reactor with a total effective volume of 10L, with a volume ratio of 3:1 between tank A and tank O. First, the two reactors were inoculated with residual sludge from a sewage treatment plant's secondary sedimentation tank and a small amount of untreated wastewater, respectively, at an activated sludge concentration of 3000mg / L after inoculation. Tank A then activated agitation was increased by 1.0 times the normal value to 2000r / min, and tank O activated aeration was initiated to control dissolved oxygen at 6mg / L. During the process, protein samples were collected and tested until protein content reached 30% by mass. Carrier I, cultured with anaerobic ammonia-oxidizing bacteria, was added to the treated tank A at a concentration of 2.0g / L, while carrier A, cultured with nitrifying bacteria, was added to the treated tank O at a concentration of 2.0g / L. Ammonia-containing wastewater was then added, and the system was commissioned using continuous water inflow. Wastewater quality: ammonia nitrogen concentration of 220 mg / L, total nitrogen concentration of 250 mg / L, and COD concentration of 350 mg / L. Tank A was agitated to initiate denitrification, operating under the following conditions: dissolved oxygen of 0.2-0.3 mg / L, pH of 7.5-7.8, and temperature of 25-30°C. Tank O was aerated with a fan to initiate nitrification, operating under the following conditions: dissolved oxygen of 2-3 mg / L, pH of 7.5-7.8, and temperature of 25-30°C.

[0063] The system startup process was completed when the ammonia nitrogen concentration in the system was 2.6 and the total nitrogen concentration was 21.8 mg / L, and the startup time was 22 days.

[0064] Example 4

[0065] The laboratory built a self-made A / O reactor with a total effective volume of 10L, with a volume ratio of 3:1 between tank A and tank O. First, the two reactors were inoculated with residual sludge from a sewage treatment plant's secondary sedimentation tank and a small amount of untreated wastewater, respectively, at an activated sludge concentration of 3000mg / L after inoculation. Tank A then activated agitation was increased by 1.0 times its normal value to 2000r / min, and tank O activated aeration was initiated to control dissolved oxygen at 6mg / L. During the process, samples were taken to test the protein content in the system until it reached 30% by mass. Carrier II, containing anaerobic ammonia-oxidizing bacteria, was added to the activated ammonia-oxidizing tank A, at a concentration of 2.0g / L. Carrier B, containing nitrifying bacteria, was added to the activated ammonia-containing wastewater. The system was then fed with continuous water inflow for commissioning. Wastewater quality: ammonia nitrogen concentration of 220 mg / L, total nitrogen concentration of 250 mg / L, and COD concentration of 350 mg / L. Tank A was agitated to initiate denitrification, operating under the following conditions: dissolved oxygen of 0.2-0.3 mg / L, pH of 7.5-7.8, and temperature of 25-30°C. Tank O was aerated with a fan to initiate nitrification, operating under the following conditions: dissolved oxygen of 2-3 mg / L, pH of 7.5-7.8, and temperature of 25-30°C.

[0066] The system startup process is completed when the ammonia nitrogen concentration in the system is 3.7 and the total nitrogen concentration is 23.5 mg / L. The startup time is 24 days.

[0067] Example 5

[0068] The laboratory built a self-made A / O reactor with a total effective volume of 10L, with a volume ratio of 3:1 between tank A and tank O. First, the two reactors were inoculated with residual sludge from a sewage treatment plant's secondary sedimentation tank and a small amount of untreated wastewater, respectively, at an activated sludge concentration of 3000mg / L after inoculation. Tank A then activated agitation was increased by 1.0 times its normal value to 2000r / min, and tank O activated aeration was initiated to control dissolved oxygen at 6mg / L. During the process, protein content in the system was sampled and tested until it reached 30% by mass. Carrier III, containing anaerobic ammonia-oxidizing bacteria, was added to the activated ammonia-oxidizing tank A, at a concentration of 2.0g / L. Carrier C, containing nitrifying bacteria, was added to the activated ammonia-containing wastewater. The system was then fed with continuous water inflow for commissioning. Wastewater quality: ammonia nitrogen concentration of 220 mg / L, total nitrogen concentration of 250 mg / L, and COD concentration of 350 mg / L. Tank A was agitated to initiate denitrification, operating under the following conditions: dissolved oxygen of 0.2-0.3 mg / L, pH of 7.5-7.8, and temperature of 25-30°C. Tank O was aerated with a fan to initiate nitrification, operating under the following conditions: dissolved oxygen of 2-3 mg / L, pH of 7.5-7.8, and temperature of 25-30°C.

[0069] The system startup process was completed when the ammonia nitrogen concentration in the system was 4.1 and the total nitrogen concentration was 24.1 mg / L, and the startup time was 25 days.

[0070] Example 6

[0071] A laboratory-built A / O reactor with a total effective volume of 10L was constructed, with the A tank and O tank having a volume ratio of 3:1. First, the two reactors were inoculated with residual sludge from a sewage treatment plant's secondary sedimentation tank and a small amount of untreated wastewater, respectively, at an activated sludge concentration of 3000mg / L after inoculation. Then, the A tank was subjected to vigorous agitation, increasing the agitation intensity by 1.0 times its normal value to 2000r / min, and the O tank was aerated to control the dissolved oxygen at 6mg / L. During the process, protein samples were collected and tested until the protein content reached 30% by mass. Anaerobic ammonia-oxidizing bacteria culture carrier I was added to the A tank after the treatment, and nitrifying bacteria culture carrier A was added to the O tank after the treatment, at a concentration of 5.0g / L. Ammonia-containing wastewater was then added, and the system was commissioned using continuous water inflow. Wastewater quality: ammonia nitrogen concentration of 220 mg / L, total nitrogen concentration of 250 mg / L, and COD concentration of 350 mg / L. Tank A was agitated to initiate denitrification, operating under the following conditions: dissolved oxygen of 0.2-0.3 mg / L, pH of 7.5-7.8, and temperature of 25-30°C. Tank O was aerated with a fan to initiate nitrification, operating under the following conditions: dissolved oxygen of 2-3 mg / L, pH of 7.5-7.8, and temperature of 25-30°C.

[0072] The system startup process was completed when the ammonia nitrogen concentration in the system was 3.4 and the total nitrogen concentration was 23.3 mg / L, and the startup time was 21 days.

[0073] Example 7

[0074] A laboratory-built A / O reactor with a total effective volume of 10L was constructed, with a volume ratio of 3:1 between tank A and tank O. First, the two reactors were inoculated with residual sludge from a sewage treatment plant's secondary sedimentation tank and a small amount of untreated wastewater, respectively, at an activated sludge concentration of 3000mg / L. Tank A was then subjected to high-intensity agitation, increasing the agitation intensity by 0.5 times its normal value to 1500r / min. Tank O was aerated to control the dissolved oxygen at 7mg / L, and the sludge was broken down. Samples were taken during the process to measure protein content, stopping when protein content reached 50% by mass. Carrier I, cultured with anaerobic ammonia-oxidizing bacteria, was added to the broken-down tank A at a concentration of 3.0g / L, while carrier A, cultured with nitrifying bacteria, was added to the broken-down tank O at a concentration of 3.0g / L. Ammonia-containing wastewater was then added, and the system was commissioned using continuous water inflow. Wastewater quality: ammonia nitrogen concentration of 260 mg / L, total nitrogen concentration of 300 mg / L, and COD concentration of 400 mg / L. Tank A was agitated to initiate denitrification, operating under the following conditions: dissolved oxygen of 0.4-0.5 mg / L, pH of 7.8-8.0, and temperature of 31-35°C. Tank O was aerated with a fan to initiate nitrification, operating under the following conditions: dissolved oxygen of 3-4 mg / L, pH of 7.8-8.0, and temperature of 31-35°C.

[0075] The system startup process was completed when the ammonia nitrogen concentration in the system was 4.4 and the total nitrogen concentration was 24.3 mg / L, and the startup time was 27 days.

[0076] Example 8

[0077] The startup process and conditions were the same as in Example 3, except that the activated sludge decomposition treatment control system was stopped after the protein content increased to 20%. 30 days after the system was started, the ammonia nitrogen concentration was 3.8 and the total nitrogen concentration was 23.9 mg / L.

[0078] Comparative Example 1

[0079] 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. 47 days after system startup, the effluent ammonia nitrogen concentration was less than 5 mg / L and the total nitrogen concentration was less than 25 mg / L, indicating a longer startup time.

[0080] Comparative Example 2

[0081] 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. 49 days after system startup, the effluent ammonia nitrogen concentration was less than 5 mg / L and the total nitrogen concentration was less than 25 mg / L, indicating a longer startup time.

[0082] Comparative Example 3

[0083] The startup process and conditions were the same as in Example 3, except that the anaerobic ammonia-oxidizing bacteria carrier IV of Example 1 was used. 50 days after the system was started, the effluent ammonia nitrogen concentration was less than 5 mg / L and the total nitrogen concentration was less than 25 mg / L, indicating a longer startup time.

[0084] Comparative Example 4

[0085] The startup process and conditions were the same as in Example 3, except that the anaerobic ammonia-oxidizing bacteria carrier V of Example 1 was used. 53 days after the system was started, the effluent ammonia nitrogen concentration was less than 5 mg / L and the total nitrogen concentration was less than 25 mg / L, indicating a longer startup time.

[0086] Comparative Example 5

[0087] The startup process and conditions were the same as in Example 3, except that carrier E for culturing nitrifying bacteria and carrier V for culturing anaerobic ammonia-oxidizing bacteria from Example 1 were used. Sixty-one days after system startup, the effluent ammonia nitrogen concentration was less than 5 mg / L and the total nitrogen concentration was less than 25 mg / L, indicating a longer startup time.

[0088] Comparative Example 6

[0089] The startup process and conditions were the same as in Example 3, except that the sludge was not broken down before the carrier was added. 44 days after system startup, the effluent ammonia nitrogen concentration was as low as 4.6 mg / L, and the total nitrogen concentration was reduced to 24.1 mg / L. This extended startup time compared to Example 3.

Claims

1. A method for rapidly starting the denitrification function of an A / O system, comprising: (1) The anaerobic tank (A tank) and the aerobic tank (O tank) are pre-inoculated with activated sludge rich in denitrifying bacteria, and then the sludge is decomposed respectively; (2) loading a carrier for culturing anaerobic ammonia-oxidizing bacteria into the A pool that has been cracked in step (1), loading a carrier for culturing nitrifying bacteria into the O pool that has been cracked in step (1), and then adding ammonia-containing sewage to start the system to continuously feed water until the system startup 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 the carrier for culturing nitrifying bacteria, heterotrophic bacteria account for 10% to 30% of the carrier mass.

3. The method according to claim 1, characterized in that 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.

4. The method according to claim 1, wherein In step (1), activated sludge rich in denitrifying bacteria is inoculated into tanks A and O at a sludge concentration of 3000-4000 mg / L.

5. The method according to claim 1, wherein In step (1), the sludge is subjected to a cracking treatment so that the extracellular polymeric substances are increased to no more than 60% by weight of protein.

6. The method according to claim 1, characterized in that In step (1), the sludge is cracked so that the extracellular polymeric substances are increased to 30% to 40% by weight of protein.

7. The method according to claim 1, characterized in that In step (1), the cracking treatment method of pool A is strong stirring; the cracking treatment method of pool O is excessive aeration.

8. The method according to claim 1, characterized in that In step (2), the loading amount of the carrier for culturing nitrifying bacteria and the carrier for culturing anaerobic ammonia oxidizing bacteria are independently added according to the content in the system of 1-5 g / L.

9. The method according to claim 1, characterized in that In step (2), the operating conditions of pool A are: dissolved oxygen 0.1~1.0 mg / L, pH 7.5~8.5, and temperature 25~40°C; the operating conditions of pool O are: dissolved oxygen 1~5 mg / L, pH 7.5~8.5, and temperature 25~40°C.

10. The method according to claim 9, characterized in that In step (2), the operating conditions of pool A are: dissolved oxygen 0.2~0.5 mg / L; the operating conditions of pool O are: dissolved oxygen 2~4 mg / L.

11. The method according to claim 1, wherein In step (2), when the ammonia nitrogen concentration in the effluent of the system is less than 5 mg / L and the total nitrogen concentration is less than 25 mg / L, the system startup is completed.

12. The method according to claim 1 or 9, characterized in that The water quality of the ammonia-containing sewage is as follows: ammonia nitrogen concentration is 200-300 mg / L, total nitrogen is 200-400 mg / L, and COD concentration is 300-400 mg / L.

13. 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.

14. The method according to claim 13, characterized in that The heterotrophic bacteria is yeast; the yeast is Candida tropicalis.

15. 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.

16. The method according to claim 15, 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.

17. 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.

18. 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.