A method for quickly starting the denitrification function of a sewage treatment system

Abstract

The present invention discloses a method for quickly starting the denitrification function of a sewage treatment system. The method comprises: (1) pre-inoculating activated sludge rich in denitrifying bacteria in the sewage treatment system, and then cracking the sludge; (2) loading a carrier for cultivating nitrifying bacteria into the sludge system that has been cracked in step (1), then replenishing ammonia-containing sewage and starting the nitrification function, and operating in a batch water inlet and outlet manner; (3) when the nitrite rate in the system of step (2) reaches more than 50%, re-filling a carrier for cultivating anaerobic ammonia-oxidizing bacteria, and then operating in a continuous water inlet and outlet manner until the startup process is completed. The method of the present invention first pre-treats the activated sludge system, and then adds nitrifying bacteria carriers and anaerobic ammonia-oxidizing bacteria carriers in steps, accelerates the rapid biofilm formation of microorganisms with denitrification function, promotes the rapid construction of the system's 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 method for quickly starting a denitrification function of a sewage treatment 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 biological aerated filter of the pre-denitrification biological aerated filter process, and can achieve process effluent compliance within 120 to 140 days. However, this method requires more than three months of commissioning.

[0004] CN108083581A discloses a low-energy autotrophic denitrification municipal sewage treatment system and method, which adopts a series anaerobic decarbonization-autotrophic denitrification form to first inoculate the residual sludge of the sewage treatment plant to start the anaerobic carbon removal reactor. The anaerobic decarbonization reactor startup process requires 60 to 90 days. The subsequent startup of the autotrophic denitrification reactor requires first inoculating the entire pool with 3000 mg / L anaerobic ammonia oxidation sludge for preliminary anaerobic startup, and artificially distribute water to meet the anaerobic ammonia oxidation bacteria substrate requirements. The reactor startup process requires 90 to 120 days, and the entire process startup requires 150 to 210 days.

[0005] CN108585202A discloses a process for treating domestic sewage by implementing partial short-cut nitrification, sludge fermentation coupled with denitrification and anaerobic ammonium oxidation in a sequencing batch reactor. The method involves the start-up of autotrophic denitrification: inoculating a sponge filler with a membrane in a laboratory short-cut nitrification and anaerobic ammonium oxidation integrated reactor, equivalent to a sludge concentration of 2500 mg / L, mixing it with a blank filler and adding it to the reactor, with a filling ratio of 40%, and the inlet water is water distribution. This method also requires too much biomass of seed source microorganisms, making it difficult to meet the startup requirements of large-scale engineering projects. In addition, the startup process is water distribution operation, and it is impossible to predict whether the cultured autotrophic denitrification functional microorganisms can use the actual engineering water quality.

[0006] CN106630143A discloses an integrated reactor and denitrification method for complete autotrophic denitrification with pre-denitrification. The reactor used is provided with aerobic, anoxic and anaerobic zones for respectively cultivating nitrite bacteria, short-range denitrifying bacteria and anaerobic ammonia-oxidizing bacteria. The experimental mixed liquid is refluxed through an airlift device. The short-range denitrification used controls the conversion of refluxed nitric nitrogen into nitrous acid. The step has high requirements for water quality. Excessive COD in the influent or too long HRT can cause full denitrification to destroy the balance of the reactor. Although the device is provided with aerobic, anoxic and anaerobic zones in the same reactor, the actual operation is relatively complicated, and it is difficult to ensure suitable conditions in each reaction zone. In addition, the use of an airlift device for reflux cannot arbitrarily control the reflux ratio according to the water quality, and the practicality is poor.

[0007] 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 intermittent inflow, while denitrifying agents are added during continuous 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

[0008] To address the shortcomings of existing technologies, the present invention aims to provide a method for rapidly activating the denitrification function of a sewage treatment system. This method pre-treats the activated sludge system before adding nitrifying bacteria and anaerobic ammonia-oxidizing bacteria carriers. This accelerates the rapid biofilm formation of denitrifying microorganisms, promotes the rapid establishment of the system's denitrification function, and achieves rapid system startup.

[0009] The present invention provides a method for quickly starting the denitrification function of a sewage treatment system, comprising the following steps:

[0010] (1) Pre-inoculate activated sludge rich in denitrifying bacteria in the sewage treatment system and then perform a decomposition treatment on the sludge;

[0011] (2) loading a carrier for cultivating nitrifying bacteria into the sludge system that has been cracked and treated in step (1), then adding ammonia-containing sewage and starting the nitrification function, and operating in a batch water inlet and outlet mode;

[0012] (3) When the nitrite rate in the system of step (2) reaches more than 50%, preferably 50% to 60%, the carrier for cultivating anaerobic ammonia-oxidizing bacteria is loaded, and then the system is operated in a continuous water inlet and outlet manner until the startup process is completed.

[0013] 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%.

[0014] 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.

[0015] In the present invention, in step (1), activated sludge rich in denitrifying bacteria is inoculated 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, wherein the excess sludge from the secondary sedimentation tank refers to the water content of the supernatant discharged from the sedimentation tank of the sewage treatment plant after gravity sedimentation, which is less than 99%.

[0016] In the present invention, in step (1), the sludge is subjected to a disintegration treatment so that the extracellular polymers (EPMs) are increased to no more than 65% (preferably 30% to 50%) based on the protein content, and the disintegration treatment 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 ECPs and release them into the water, thereby significantly increasing the ECPs 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.

[0017] In the present invention, in step (1), the cracking treatment method can be at least one of excessive aeration and strong stirring. The excessive aeration method is to control the dissolved oxygen concentration to be above 5 mg / L, preferably 5-6 mg / L; the strong stirring method is to increase the stirring speed, which can be increased by 500-1000 rotation speed units (rpm) compared with conventional culture.

[0018] In the present invention, in step (2), the nitrification function is activated by aeration, and each operation cycle lasts for 12 to 24 hours. The operating conditions are: dissolved oxygen greater than 2 mg / L, preferably 2 to 4 mg / L, pH 7.5 to 8.5, and temperature 25 to 40°C.

[0019] In the present invention, in step (2), the amount of the carrier for culturing nitrifying bacteria is added according to its content in the system being 1 to 5 g / L.

[0020] In the present invention, in step (3), the amount of carrier added to culture anaerobic ammonia oxidizing bacteria is 0.5 to 2 g / L based on the content in the system. The operating conditions are: dissolved oxygen 0.5 to 1.5 mg / L, pH 7.5 to 8.5, and temperature 25 to 40°C.

[0021] In the present invention, in step (3), when the total nitrogen concentration of the effluent in the system is lower than 25 mg / L, the system startup process is completed.

[0022] 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.

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

[0024] In the preparation method of the carrier for culturing nitrifying bacteria described in the present invention, 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 method for preparing a carrier for culturing nitrifying bacteria described in the present invention, 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 described herein, the organic carbon source is determined based on the specific bacterial species selected and is generally a carbon-containing organic substance such as a carbohydrate, protein, or organic acid 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 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 method for preparing a carrier for culturing nitrifying bacteria of the present invention, 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 method for preparing a carrier for culturing anaerobic ammonia-oxidizing bacteria described in the present invention, 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 method for preparing a carrier for culturing anaerobic ammonia-oxidizing bacteria described in the present invention, 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 preparation method of the carrier for culturing anaerobic ammonia-oxidizing bacteria described in the present invention, 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 by centrifugation at 10,000-15,000r / min to retain the bacterial cells.

[0033] In the preparation method of the carrier for culturing anaerobic ammonia-oxidizing bacteria described in the present invention, 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, and 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 mixture is dehydrated with acetone and the resulting product is 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 method for preparing a carrier for culturing anaerobic ammonia-oxidizing bacteria described herein, a cross-linked chitosan carrier is modified with polyethyleneimine. Specifically, the cross-linked chitosan carrier is immersed in an aqueous polyethyleneimine solution at a mass fraction of 1% to 10% and then dried. The carrier is immersed in the solution for 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, heterotrophic bacteria account for 1% to 5% of the carrier mass, and 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 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.

[0047] 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.

[0048] 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.

[0049] 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.

[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 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] Table 2 Preparation of carriers for culturing anaerobic ammonium oxidizing bacteria

[0062]

[0063]

[0064] Example 3

[0065] In a 10-liter aeration and stirring reactor, excess sludge from a sewage treatment plant's secondary sedimentation tank was inoculated to an activated sludge concentration of 3000 mg / L. Over-aeration was performed, maintaining dissolved oxygen at 6 mg / L. Protein content was sampled every 60 minutes until it reached 30% by mass. The treated sludge system was then loaded with carrier A, containing nitrifying bacteria, at a concentration of 1.5 g / L. Ammoniacal wastewater with an ammonia nitrogen concentration of 240 mg / L, a total nitrogen concentration of 280 mg / L, and a COD concentration of 320 mg / L was then added to the active volume. Nitrification was initiated with an aeration fan. After a 23-hour reaction, the system allowed to settle for 1 hour, the supernatant was discharged, and water was refilled to the active volume to begin the next cycle. The system operated under the following conditions: dissolved oxygen of 2.8-3.0 mg / L, a pH of 7.5-7.8, and a temperature of 28-30°C. When the nitrite rate in the system reaches 51%, the carrier I for culturing anaerobic ammonium oxidizing bacteria is added according to the carrier content of 0.5g / L in the system, and then the system is operated in a continuous water inlet and outlet mode. The operating conditions of the system are: dissolved oxygen 0.8-1.0mg / L, pH 7.5-7.8, and temperature 28-30℃.

[0066] The system startup process is completed when the total nitrogen concentration in the system reaches 20.5 mg / L, and the startup time is 20 days.

[0067] Example 4

[0068] In a 10-liter aeration and stirring reactor equipped with active sludge, excess sludge from a sewage treatment plant's secondary sedimentation tank was inoculated to an activated sludge concentration of 3000 mg / L. Over-aeration was performed while maintaining dissolved oxygen at 6 mg / L. Protein content was sampled every 60 minutes until it reached 50% by mass. The treated sludge system was then loaded with carrier B, containing nitrifying bacteria, at a concentration of 1.5 g / L. Ammoniacal wastewater with an ammonia nitrogen concentration of 240 mg / L, a total nitrogen concentration of 280 mg / L, and a COD concentration of 320 mg / L was then added. Nitrification was initiated with an aeration fan, and the system was operated with 24-hour water exchange. The system operated under the following conditions: dissolved oxygen of 2.0-2.5 mg / L, a pH of 7.8-8.0, and a temperature of 26-28°C. When the nitrite rate in the system reaches 51%, the carrier II for culturing anaerobic ammonium oxidizing bacteria is added according to the carrier content of 0.5g / L in the system, and then the system is operated in a continuous water inlet and outlet mode. The operating conditions of the system are: dissolved oxygen 0.5-0.8mg / L, pH 7.8-8.0, and temperature 26-28℃.

[0069] The system startup process was completed when the total nitrogen concentration in the system reached 22.5 mg / L, and the startup time was 22 days.

[0070] Example 5

[0071] In a 10-liter aeration and stirring reactor, excess sludge from a sewage treatment plant's secondary sedimentation tank was inoculated to an activated sludge concentration of 3000 mg / L. Over-aeration was performed, maintaining dissolved oxygen at 5.5 mg / L. Protein content was sampled every 60 minutes until it reached 30% by mass. The treated sludge system was loaded with carrier C, containing nitrifying bacteria, at a concentration of 1.5 g / L. Ammoniacal wastewater with an ammonia nitrogen concentration of 240 mg / L, a total nitrogen concentration of 280 mg / L, and a COD concentration of 320 mg / L was then added to the active volume. Nitrification was initiated with an aeration fan. After a 23-hour reaction, the system allowed to settle for 1 hour, the supernatant was discharged, and water was added to the active volume to begin the next cycle. The system operated under the following conditions: dissolved oxygen of 2.8-3.0 mg / L, a pH of 7.5-7.8, and a temperature of 28-30°C. When the nitrite rate in the system reaches 51%, the carrier III for culturing anaerobic ammonium oxidizing bacteria is added according to the carrier content of 0.5g / L in the system, and then the system is operated in a continuous water inlet and outlet mode. The operating conditions of the system are: dissolved oxygen 0.5-0.6mg / L, pH 7.5-7.8, and temperature 28-30℃.

[0072] The system startup process was completed when the total nitrogen concentration in the system reached 24.5 mg / L, and the startup time was 23 days.

[0073] Example 6

[0074] In a 10-liter aeration and stirring reactor equipped with active sludge, excess sludge from a sewage treatment plant's secondary sedimentation tank was inoculated to an activated sludge concentration of 4000 mg / L. Over-aeration was performed, maintaining dissolved oxygen at 6 mg / L. Protein content was sampled every 60 minutes until it reached 30% by mass. The treated sludge system was then loaded with carrier A, containing nitrifying bacteria, at a concentration of 3.0 g / L. Ammoniacal wastewater with an ammonia nitrogen concentration of 240 mg / L, a total nitrogen concentration of 280 mg / L, and a COD concentration of 320 mg / L was then added to the active volume. Nitrification was initiated with an aeration fan. After 11 hours of reaction and 1 hour of settling, the supernatant was discharged and the system was refilled with water to the active volume for the next cycle. The system operated under the following conditions: dissolved oxygen of 3.0-3.8 mg / L, a pH of 7.5-7.8, and a temperature of 28-30°C. When the nitrite rate in the system reaches 51%, the carrier I for culturing anaerobic ammonium oxidizing bacteria is added according to the carrier content of 1.5g / L in the system, and then the system is operated in a continuous water inlet and outlet mode. The operating conditions of the system are: dissolved oxygen 1.0-1.2mg / L, pH 7.5-7.8, and temperature 28-30℃.

[0075] The system startup process is completed when the total nitrogen concentration in the system reaches 21.3 mg / L, and the startup time is 20 days.

[0076] Example 7

[0077] In a 10-liter aeration and stirring reactor equipped with active sludge, excess sludge from a sewage treatment plant's secondary sedimentation tank was inoculated to an activated sludge concentration of 4000 mg / L. Over-aeration was performed, maintaining dissolved oxygen at 6 mg / L. Protein content was sampled every 60 minutes until it reached 30% by mass. The treated sludge system was then loaded with carrier A, containing 5.0 g / L of nitrifying bacteria. Ammonia-containing wastewater with an ammonia nitrogen concentration of 280 mg / L, a total nitrogen concentration of 300 mg / L, and a COD concentration of 350 mg / L was then added to the active volume. Nitrification was initiated with an aeration fan. After 11 hours of reaction and 1 hour of settling, the supernatant was discharged and the system was refilled with water to the active volume for the next cycle. The system operated under the following conditions: dissolved oxygen of 3.0-4.0 mg / L, a pH of 7.6-8.0, and a temperature of 30-32°C. When the nitrite rate in the system reaches 51%, the carrier I for culturing anaerobic ammonium oxidizing bacteria is added according to the carrier content of 2.0g / L in the system, and then the system is operated in a continuous water inlet and outlet mode. The operating conditions of the system are: dissolved oxygen 1.0mg / L, pH value 7.6-8.0, and temperature 30-32℃.

[0078] The system startup process is completed when the total nitrogen concentration in the system reaches 23.6 mg / L, and the startup time is 20 days.

[0079] Example 8

[0080] The startup process and conditions were the same as in Example 3, except that the activated sludge decomposition treatment system was stopped after the protein content increased to 20%. 29 days after the system was started, the total nitrogen concentration was 24.5 mg / L.

[0081] Comparative Example 1

[0082] The startup process and conditions were the same as those in Example 3, except that no carrier for cultivating nitrifying bacteria and anaerobic ammonia-oxidizing bacteria were added. 50 days after the system was started, the ammonia nitrogen concentration was still as high as 28 mg / L and the total nitrogen concentration was 40 mg / L. After another 20 days of startup, the total nitrogen concentration in the effluent was lower than 25 mg / L, indicating a longer startup time.

[0083] Comparative Example 2

[0084] 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. 45 days after the system was started, the total nitrogen concentration in the effluent was lower than 25 mg / L, indicating a longer startup time.

[0085] Comparative Example 3

[0086] 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. 48 days after the system was started, the total nitrogen concentration in the effluent was lower than 25 mg / L, indicating a longer startup time.

[0087] Comparative Example 4

[0088] 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. 46 days after the system was started, the total nitrogen concentration in the effluent was less than 25 mg / L, indicating a longer startup time.

[0089] Comparative Example 5

[0090] 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. 49 days after the system was started, the total nitrogen concentration in the effluent was lower than 25 mg / L, indicating a longer startup time.

[0091] Comparative Example 6

[0092] 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 were used in Example 1. 59 days after system startup, the effluent total nitrogen concentration was less than 25 mg / L, indicating a longer startup time.

[0093] Comparative Example 7

[0094] The startup process and conditions were the same as in Example 3, except that no cracking was performed in step (2). Forty-two days after system startup, the total nitrogen concentration decreased to 24.7 mg / L. Compared with Example 3, the startup time was longer.

Claims

1. A method for quickly starting the denitrification function of a sewage treatment system, comprising the following steps: (1) Pre-inoculate activated sludge rich in denitrifying bacteria in the sewage treatment system and then perform a 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), then adding ammonia-containing sewage and starting the nitrification function, and operating in a batch water inlet and outlet mode; (3) When the nitrite rate in the system of step (2) reaches more than 50%, the carrier for cultivating anaerobic ammonia-oxidizing bacteria is loaded, and then the system is operated in a continuous water inlet and outlet manner 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 nitrite rate in the system of step (2) reaches 50% to 60%, the carrier for cultivating anaerobic ammonia oxidizing bacteria is loaded.

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

4. The method according to claim 1, wherein 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.

5. The method according to claim 1, wherein In step (1), activated sludge rich in denitrifying bacteria is inoculated at a sludge concentration of 3000-4000 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, measured by the mass content of protein, increases to no more than 65%, and the cracking treatment is stopped.

7. The method according to claim 5, characterized in that In step (1), the sludge is subjected to a cracking treatment so that the extracellular polymer content increases to 30% to 50% based on the mass content of protein, and the cracking treatment is stopped.

8. The method according to claim 1, characterized in that In step (1), the cracking treatment method adopts at least one of excessive aeration and strong stirring.

9. The method according to claim 1, characterized in that In step (2), the nitrification function is started by aeration, and each operation cycle lasts 12 to 24 hours; the operating conditions are: dissolved oxygen greater than 2 mg / L, pH value 7.5 to 8.5, and temperature 25 to 40°C.

10. The method according to claim 9, characterized in that In step (2), the operating conditions are that the dissolved oxygen is 2-4 mg / L.

11. The method according to claim 1, wherein In step (2), the amount of the carrier for culturing nitrifying bacteria is added according to its content in the system of 1-5 g / L.

12. The method according to claim 1, characterized in that In step (3), the amount of carrier for culturing anaerobic ammonia-oxidizing bacteria is added according to its content in the system of 0.5-2 g / L; the operating conditions are: dissolved oxygen 0.5-1.5 mg / L, pH 7.5-8.5, and temperature 25-40°C.

13. The method according to claim 1, wherein In step (3), when the total nitrogen concentration of the effluent in the system is lower than 25 mg / L, the system startup process is completed.

14. The method according to claim 1, wherein 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.

15. 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.

16. The method according to claim 15, characterized in that The heterotrophic bacteria is yeast; the yeast is Candida tropicalis.

17. The method according to claim 1, wherein In the method for preparing a carrier for culturing anaerobic ammonia-oxidizing bacteria, the organic carbon source is selected from at least one of sugars, proteins, and organic acids conventionally used in the cultivation of heterotrophic bacteria.

18. The method according to claim 17, characterized in that The organic carbon source is at least one of glucose, hexose, xylose, sucrose and starch.

19. 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 6.0-7.0; static culture or shaking culture, static culture is stirred every 30-60 minutes, and the shaking culture speed is 200-600 r / min.

20. The method according to claim 19, 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.

21. 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.

22. 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.

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