A method for storing activated sludge and quickly starting a biochemical unit

Abstract

The present invention discloses a method for storing activated sludge and quickly starting a biochemical unit. The method includes the following steps: (1) treating the activated sludge during shutdown: before shutdown, adding activated carbon, adjusting the aeration volume so that the dissolved oxygen is controlled at 5 mg / L or above, fully aerating and mixing the activated carbon with the mud-water mixture in the sewage treatment tank, stopping aeration, and allowing the mixture to settle naturally. Discharging the supernatant so that the MLSS of the solid matter in the remaining mud-water mixture reaches 15 g / L or above, and storing the mixture at room temperature; (2) storing the sludge at room temperature during shutdown: storing the sludge in a micro-aerobic state during the initial storage period, and then supplementing the carbon source for further storage; (3) starting the biochemical unit at startup: at startup, inoculating the sludge stored in step (2) into the sewage treatment tank, adding an adsorbent, and first simmering and exploding the sludge, and then injecting wastewater for startup. The method can maintain the activity of the activated sludge during storage, and does not require long-term acclimation of the sludge during use. The biochemical unit of the sewage treatment plant can be quickly started after activation.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment, and in particular relates to a method for preserving activated sludge and quickly starting a biochemical unit. Background Art

[0002] To ensure efficient and stable operation of production units, reduce equipment corrosion and wear, and achieve energy conservation and consumption reduction goals, refineries and chemical companies need to shut down their production units for maintenance annually. During these shutdowns, the wastewater treatment units are also shut down. When the production units are returned to service after maintenance, the wastewater treatment units must be restarted in advance to receive incoming water for treatment.

[0003] When the biochemical unit of a sewage treatment plant is started, it must be inoculated with sludge. The inoculated sludge requires a certain amount of time to be cultivated and domesticated so that the biological community in the sludge can adapt to and treat the pollutants in the sewage. Only when the functional microorganisms reach a sufficient number and activity can the production unit operate at full capacity. Currently, there are two sources of inoculated sludge: one is the sludge from the original sewage treatment plant, and the other is the residual activated sludge introduced from other sewage treatment plants. If the sludge from the original sewage treatment plant is inoculated, the sludge needs to be stored first and then rejuvenated before use when the plant is started. During the storage process, this part of the sludge often does not meet the storage conditions, and anaerobic fermentation and other reactions will occur, thereby affecting the biological activity. A large amount of sludge will die during reinoculation, affecting the effluent quality and sewage treatment effect. The residual sludge from other sewage treatment plants that have not been shut down is used as the seed sludge for restarting. Although the biological activity is good, the biological communities formed are different due to the different water quality of the sewage treated by different plants. Therefore, when inoculating the sludge from other sewage treatment plants, the sludge needs to be directed domesticated first. For example, the residual activated sludge from the refinery sewage treatment plant is inoculated into the coal gasification sewage treatment unit used to treat high ammonia nitrogen concentrations. The sludge domestication cycle usually takes 1 to 2 months, resulting in a relatively long restart cycle for the biochemical unit of the sewage treatment plant, and it cannot quickly enter the full-load operation state, which in turn affects the start-up progress of the production unit and the benefits of the enterprise.

[0004] If the original sludge can be preserved when the sewage treatment plant is shut down, it can be directly added and used during startup, shortening the start-up cycle and achieving rapid startup of the plant, so that the production plant can operate at full capacity as soon as possible.

[0005] CN201710188104.3 discloses a method for preserving activated sludge flora in a sequencing batch reactor. The method involves cooling the activated sludge in an autotrophic denitrification tank; then mixing it with water and placing it in a bioretention tank to adjust the pH; and periodically adding nutrient solution to the tank to control the dissolved oxygen concentration. This method can achieve long-term preservation of the activated sludge flora in the autotrophic denitrification tank, but requires low temperatures. For most companies, maintaining a storage temperature of 2-5°C increases storage costs. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention provides a method for preserving activated sludge and rapidly activating a biochemical unit. This method maintains the activated sludge's activity during storage, eliminating the need for prolonged acclimation. Rapid activation of the biochemical unit in a sewage treatment plant is achieved simply by activation. The method is simple, easy to control, and implement.

[0007] The present invention provides a method for storing activated sludge and quickly starting a biochemical unit, comprising the following steps:

[0008] (1) Treatment of activated sludge during shutdown: before shutdown, add activated carbon and adjust the aeration volume to control the dissolved oxygen concentration to above 5 mg / L, preferably 5.5-7.0 mg / L. After fully aerating and mixing the activated carbon with the mud-water mixture in the sewage treatment tank for 12-24 hours, stop aeration and allow it to settle naturally. Discharge the supernatant so that the MLSS of the solid matter in the remaining mud-water mixture reaches above 15 g / L, preferably 20-25 g / L. Store in a structure equipped with aeration or stirring, preferably a structure with an aeration system, and store at room temperature.

[0009] (2) Sludge storage at room temperature during shutdown: micro-aerobic storage is performed during the initial storage period, and then carbon source is added for continued storage;

[0010] (3) Start-up of the biochemical unit at the start-up: At the start-up, the sludge stored in step (2) is inoculated into the sewage treatment pool, adsorbent is added, and the simmering and explosion treatment is first performed, and then actual wastewater is injected for startup.

[0011] In the method of the present invention, the activated sludge in step (1) is the activated sludge from the biochemical unit of a sewage treatment plant after a coal chemical enterprise has been shut down for maintenance.

[0012] In the method of the present invention, the ammonia nitrogen concentration in the supernatant of step (1) is set to 10-20 mg / L, and the COD concentration is set to 80-100 mg / L.

[0013] In the method of the present invention, the activated carbon in step (1) can be powdered activated carbon well known to those skilled in the art, such as coal-based powdered activated carbon. The activated carbon is added in an amount such that its mass concentration in the system after addition is 100 to 500 mg / L.

[0014] In the method of the present invention, the room temperature storage in step (2) is performed at room temperature, generally at 10-35° C. The microaerobic storage is performed by controlling the dissolved oxygen concentration of the storage system to 0.1 mg / L-0.5 mg / L.

[0015] In the method of the present invention, the first storage period in step (2) refers to the first 1 / 3 to 1 / 2 of the storage period, after which the carbon source is added and the storage is completed. Depending on the shutdown and maintenance period, the entire storage period is generally 30 to 60 days.

[0016] In the method of the present invention, the carbon source in step (2) can be at least one of glucose, methanol, acetic acid, sodium acetate, etc., preferably methanol. The carbon source in step (2) is supplemented according to the COD concentration in the system increasing by 1 to 30 mg / L after addition.

[0017] In the method of the present invention, the adsorbent in step (3) is based on cross-linked chitosan embedded with calcium carbonate, on which heterotrophic bacteria are adsorbed and grown. In the adsorbent, the heterotrophic bacteria account for 5% to 50% of the adsorbent mass, preferably 10% to 30%, and the cross-linked chitosan embedded with calcium carbonate accounts for 50% to 95% of the adsorbent mass, preferably 70% to 90%. In the cross-linked chitosan embedded with calcium carbonate, the mass ratio of chitosan to calcium carbonate is 1 to 5:0.5 to 5.

[0018] In the method of the present invention, the adsorbent described in step (3) is prepared by the following method: first, a cross-linked chitosan carrier embedded with calcium carbonate is prepared; the cross-linked chitosan carrier embedded with calcium carbonate is added to a heterotrophic bacteria culture system using an organic carbon source for adsorption growth, the culture is cultured until the late logarithmic growth stage, and the solid matter is taken out and dried to obtain the adsorbent.

[0019] In the method of the present invention, in the preparation method of the adsorbent, 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.

[0020] In the method of the present invention, the heterotrophic bacteria in the adsorbent 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.

[0021] In the method of the present invention, in the preparation method of the adsorbent, 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, organic acids, etc. conventionally used for the cultivation of 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.

[0022] In the method of the present invention, in the preparation method of the adsorbent, the heterotrophic bacteria are cultured under the following conditions: 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 continued until the late logarithmic growth stage, generally for 24-80 hours.

[0023] In the method of the present invention, in the preparation method of the adsorbent, the drying temperature is 25-50° C., and the drying time is 1-5 hours.

[0024] In the method of the present invention, step (3) is to inoculate the stored sludge and adsorbent at the start of operation at one time. The amount of adsorbent added is based on the ratio of 50 to 100 mg / L of the mixed solution added to the system. Clean water is then added to make the activated sludge concentration 4000 to 5000 mg / L. After inoculation, the simmering and blasting treatment is carried out for 24 to 60 hours. After the simmering and blasting, the supernatant with suspended debris is discharged and actual wastewater is added for startup. The water quality of the actual wastewater is generally: an ammonia nitrogen concentration of 100 to 500 mg / L and a COD concentration of 500 to 1000 mg / L. The actual wastewater is the wastewater treated during normal operation. The wastewater treated before shutdown is the actual wastewater.

[0025] In the method of the present invention, in step (3), when the COD concentration in the effluent is below 60 mg / L, the ammonia nitrogen concentration is below 8 mg / L, and the total nitrogen is below 30 mg / L, the stored sludge completes the rapid startup process of the system.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) By adding activated carbon and increasing dissolved oxygen before shutdown, the present invention provides nutrients and a microaerobic environment for the sludge during storage, thereby preventing changes in the microbial community structure or sludge inactivation. The activated sludge preserved by the present method can be used to start up the original sewage treatment plant, achieving full capacity within a week, achieving pollutant treatment that meets standards, and maintaining stable plant operation.

[0028] (2) Unlike the prior art which uses low temperature, anoxic conditions, drying, and regular supplementation of nutrients, the present invention does not require additional dissolved oxygen concentration and carbon source during the storage period, so that heterotrophic aerobic bacteria can not only utilize the organic matter adsorbed in the activated carbon to survive under facultative anaerobic conditions but also undergo endogenous respiration to release ammonia nitrogen and intracellular energy storage substances for the cell synthesis of nitrifying bacteria with low dissolved oxygen requirements, thereby maintaining the activity of various functional microorganisms in the activated sludge.

[0029] (3) The sludge preserved by the method of the present invention is supplemented with an adsorbent composed of a combination of positively charged cross-linked chitosan and heterotrophic bacteria at the start-up, which can quickly increase the biological density and achieve rapid startup of the denitrification function after the device is inspected and maintained. This solves the problem of long acclimatization time due to unreasonable biological communities and long startup period due to improper sludge storage when inoculating other sludges, thereby achieving rapid startup of the biochemical unit without affecting the start-up progress of the production device.

[0030] (4) The method of the present invention does not require low temperature conditions during the storage of sludge, and can be stored at room temperature, thus saving costs. DETAILED DESCRIPTION

[0031] The following examples are used to describe the method and effects of the present invention in detail. The examples are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures, but the scope of protection of the present invention is not limited to the following examples.

[0032] 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.

[0033] In the examples of the present invention, COD concentration was determined according to GB11914-89, "Water quality—Determination of chemical oxygen demand—Dichromate method." Ammonia nitrogen concentration was determined according to GB7478-87, "Water quality—Determination of ammonium—Distillation and titration method." Total nitrogen concentration was determined according to GB11894-89, "Water quality—Determination of total nitrogen—Alkaline potassium persulfate digestion and ultraviolet spectrophotometry."

[0034] Example 1

[0035] Preparation of adsorbent

[0036] 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.

[0037] The calcium carbonate-encapsulated chitosan microcarriers were added to a xylose-based culture system of Candida tropicalis for adsorption growth. 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 adsorbent A with a chitosan core. Testing revealed that heterotrophic bacteria accounted for 30% of the adsorbent A.

[0038] Compared with the prepared adsorbent A, the other conditions remained unchanged, and the only difference was that the culture system of Lactobacillus using glucose was used instead of the culture system of Candida tropicalis using xylose, to prepare adsorbent B.

[0039] Compared with the prepared adsorbent A, other conditions remained unchanged, and the only difference was that the culture system of Desulfuromonas using sucrose was used instead of the culture system of Candida tropicalis using xylose, to prepare adsorbent C.

[0040] Compared with the prepared adsorbent A, other conditions remained unchanged, with the only difference being that: during the preparation of chitosan, 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 the mixture was reacted for 2 hours before centrifugation and precipitation. Other conditions remained unchanged, and adsorbent D was prepared.

[0041] Compared with the prepared adsorbent A, the other conditions remained unchanged, and the only difference was that heterotrophic denitrifying bacteria was used instead of tropical yeast to prepare adsorbent E.

[0042] Table 1 Preparation of adsorbent

[0043] Adsorbent type Chitosan microcarrier preparation Microbial species Carbon source type Proportion of heterotrophic bacteria Adsorbent A Join Kinipen Candida tropicalis Xylose 30％ Adsorbent B Join Kinipen Lactobacillus glucose 10％ Adsorbent C Join Kinipen Desulfuromonas sucrose 20％ Adsorbent D Add glutaraldehyde Candida tropicalis Xylose 26％ Adsorbent E Join Kinipen Heterotrophic denitrifying bacteria Xylose 15％

[0044] Example 2

[0045] The coal chemical wastewater treatment unit of a certain refining enterprise treats wastewater with a COD concentration of 500-700 mg / L and an ammonia nitrogen concentration of 200-300 mg / L. The sludge concentration MLSS in the original system is 2800 mg / L.

[0046] When the device is shut down, 300L of mud-water mixture from the sewage treatment plant is placed in a storage tank with aeration function, 100g of activated carbon is added first, and the aeration volume is adjusted to make the dissolved oxygen concentration 5.5mg / L. The activated carbon and the mud-water mixture in the sewage treatment tank are fully aerated and mixed for 24h, then aeration is stopped and allowed to settle naturally, and the supernatant is discharged so that the MLSS of the solid matter in the remaining mud-water mixture is about 25g / L, the ammonia nitrogen concentration in the clear liquid is 10.5mg / L, and the COD concentration is 80.9mg / L. The sludge is stored at room temperature.

[0047] During the activated sludge preservation process, microaerobic preservation is carried out for the first 20 days, and the dissolved oxygen concentration of the preservation system is controlled to 0.2 mg / L. After 20 days, methanol is added according to the COD concentration after addition of 15 mg / L and the sludge is preserved for another 20 days. The preservation period at 25-30°C is 40 days.

[0048] A small-scale 50L SBR treatment unit with a treatment load consistent with that of a sewage treatment plant was built in the laboratory to simulate a sewage treatment plant for commissioning tests. Prior to startup, the reactor was inoculated with stored activated sludge. Adsorbent A from Example 1 was added at a ratio of 50 mg / L to the mixed liquor after addition. Clean water was then added to an activated sludge concentration of 4200 mg / L. The sludge was simmered for 24 hours, and the supernatant containing suspended debris was discharged. Actual wastewater treated by the original sewage treatment unit was then added for startup. The SBR treatment unit operated for 12 hours, with water inflow for 2 hours per cycle, and the reaction began simultaneously with the inflow. Each cycle consisted of 6 hours of aeration, 4 hours of stirring, 1 hour of sedimentation, and 1 hour of drainage. Operating conditions were: dissolved oxygen 2-5 mg / L, pH 7-8, and temperature 30-35°C.

[0049] On the fifth day of operation, the COD concentration in the water was detected to be 48 mg / L, the ammonia nitrogen concentration was 4.8 mg / L, and the total nitrogen concentration was 25.9 mg / L. The preserved sludge completed the rapid startup process of the system.

[0050] Example 3

[0051] The coal chemical enterprise sewage treatment device and the treated wastewater are the same as those in Example 2.

[0052] When the device is shut down, 300L of mud-water mixture from the sewage treatment plant is placed in a storage tank with aeration function, 30g of activated carbon is added first, and the aeration volume is adjusted to make the dissolved oxygen concentration 6.0mg / L. The activated carbon and the mud-water mixture in the sewage treatment tank are fully aerated and mixed for 18h, then aeration is stopped and allowed to settle naturally, and the supernatant is discharged so that the MLSS of the solid matter in the remaining mud-water mixture is about 35g / L, the ammonia nitrogen concentration in the clear liquid is 15mg / L, and the COD concentration is 90.4mg / L. The sludge is stored at room temperature.

[0053] During the activated sludge preservation process, microaerobic preservation is carried out for the first 25 days, and the dissolved oxygen concentration of the preservation system is controlled at about 0.3 mg / L. After 25 days, glucose is added according to the COD concentration after addition of 10 mg / L and the sludge is preserved for another 25 days. The preservation period at 20-25°C is 50 days.

[0054] The laboratory built a small-scale treatment device with a 50L treatment load consistent with that of a sewage treatment plant, and simulated a sewage treatment plant for a start-up test. Before startup, the preserved activated sludge was inoculated into the reactor. At the same time, the adsorbent B of Example 1 was added according to the proportion of 100 mg / L in the mixed liquid after addition. Clean water was added to the activated sludge concentration to 4500 mg / L. The simmering treatment was carried out for 36 hours. The supernatant with suspended debris was discharged, and then the wastewater treated by the original sewage treatment device was added for startup. The SBR treatment device has an operating cycle of 8 hours, in which water is introduced for 2 hours in each cycle, and the reaction begins at the same time as the water is introduced. Each cycle is set to aeration for 3 hours, stirring for 3 hours, sedimentation for 1 hour, and drainage for 1 hour. The operating conditions are: dissolved oxygen 2-5 mg / L, pH 7-8, and temperature 30-35°C.

[0055] On the sixth day of operation, the COD concentration in the water was detected to be 56 mg / L, the ammonia nitrogen concentration was 7.5 mg / L, and the total nitrogen concentration was 28.9 mg / L. The preserved sludge completed the rapid startup process of the system.

[0056] Example 4

[0057] The coal chemical enterprise device and wastewater treatment are the same as those in Example 2.

[0058] When the device is shut down, 300L of mud-water mixture from the sewage treatment plant is placed in a storage tank with aeration function, 50g of activated carbon is added first, and the aeration volume is adjusted to make the dissolved oxygen concentration greater than 6.5mg / L. The activated carbon and the mud-water mixture in the sewage treatment tank are fully aerated and mixed for 12h, then aeration is stopped and allowed to settle naturally, and the supernatant is discharged so that the MLSS of the solid matter in the remaining mud-water mixture is about 30g / L, the ammonia nitrogen concentration in the clear liquid is 18.9mg / L, and the COD concentration is 97.2mg / L. The sludge is stored at room temperature.

[0059] During the activated sludge preservation process, microaerobic preservation is carried out for the first 15 days, and the dissolved oxygen concentration of the preservation system is controlled at about 0.3 mg / L. After 15 days, sodium acetate is added according to the COD concentration after addition of 30 mg / L and the sludge is preserved for another 15 days. The preservation period at 20-25°C is 30 days.

[0060] A 50L small-scale treatment unit with a treatment load consistent with that of a sewage treatment plant was built in the laboratory. A start-up test was conducted to simulate a sewage treatment plant, and the operation was the same as in Example 2. The preserved activated sludge was inoculated into the reactor, and adsorbent C from Example 1 was added at a ratio of 80 mg / L to the mixed liquor after addition. Clean water was added to an activated sludge concentration of 4000 mg / L. The sludge was simmered and exploded for 48 hours, and the supernatant containing suspended debris was discharged. The reactor was then started by adding wastewater treated by the original sewage treatment unit. The operating conditions were: dissolved oxygen 2-5 mg / L, pH 7-8, and temperature 30-35°C.

[0061] When the COD concentration in the water was detected to be 58 mg / L, the ammonia nitrogen concentration was 7.8 mg / L, and the total nitrogen concentration was 28.2 mg / L after 7 days of operation, the preserved sludge completed the rapid startup process of the system.

[0062] Example 5

[0063] The rest is the same as Example 2, except that the absorbent added at the start-up is the adsorbent D of Example 1.

[0064] On the fifth day of operation, the COD concentration in the water was detected to be 51 mg / L, the ammonia nitrogen concentration was 7.8 mg / L, and the total nitrogen concentration was 27.9 mg / L. The preserved sludge completed the rapid startup process of the system.

[0065] Comparative Example 1

[0066] The coal chemical enterprise device and wastewater treatment are the same as those in Example 2.

[0067] When the device is shut down, 300L of mud-water mixture from the sewage treatment plant is placed in a storage tank with aeration function. The aeration volume is adjusted to make the dissolved oxygen concentration 5.5mg / L, and then aeration is stopped after 24 hours. It is allowed to settle naturally, and the supernatant is discharged so that the MLSS of solids in the remaining mud-water mixture is about 25g / L, the ammonia nitrogen concentration in the clear liquid is 12.5mg / L, and the COD concentration is 80.9mg / L. The sludge is stored at room temperature.

[0068] During the activated sludge preservation process, microaerobic preservation is carried out for the first 20 days, and the dissolved oxygen concentration of the preservation system is controlled to 0.2 mg / L. After 20 days, methanol is added according to the COD concentration after addition of 15 mg / L and the sludge is preserved for another 20 days. The preservation period at 25-30°C is 40 days.

[0069] The laboratory built a small, 50-liter treatment unit with a load consistent with a sewage treatment plant, and conducted a start-up test simulating a sewage treatment plant. Prior to startup, the reactor was inoculated with stored activated sludge. Clean water was then added to an activated sludge concentration of 4200 mg / L. The sludge was then simmered for 24 hours. The supernatant, containing suspended debris, was then drained and filled with actual wastewater from the original sewage treatment plant for startup. Operating conditions were: dissolved oxygen 2-5 mg / L, pH 7-8, and temperature 30-35°C.

[0070] On the fifth day of operation, the system failed to achieve a quick start when the COD concentration in the water was detected to be 260 mg / L, the ammonia nitrogen concentration was 148 mg / L, and the total nitrogen concentration was 159 mg / L. On the 58th day of operation, the COD concentration in the water was detected to be 57.2 mg / L, the ammonia nitrogen concentration was 7.5 mg / L, and the total nitrogen concentration was 25.1 mg / L.

[0071] Comparative Example 2

[0072] Other conditions were the same as in Example 2, except that no activated carbon was added during the sludge aeration process when the system was shut down. On the fifth day of operation, the COD concentration in the water was detected to be 240 mg / L, the ammonia nitrogen concentration was 88 mg / L, and the total nitrogen concentration was 97 mg / L, and the system failed to achieve a rapid startup. On the 53rd day of operation, the COD concentration in the water was detected to be 57.7 mg / L, the ammonia nitrogen concentration was 6.6 mg / L, and the total nitrogen concentration was 27.1 mg / L.

[0073] Comparative Example 3

[0074] The system was otherwise the same as in Example 2, except that no adsorbent was added during the start-up of the simulated sewage treatment plant. On the fifth day of operation, the COD concentration in the water was 200 mg / L, the ammonia nitrogen concentration was 108 mg / L, and the total nitrogen concentration was 109 mg / L, resulting in the system failing to achieve a rapid startup. On the 47th day of operation, the COD concentration in the water was 58.5 mg / L, the ammonia nitrogen concentration was 7.9 mg / L, and the total nitrogen concentration was 28.9 mg / L.

[0075] Comparative Example 4

[0076] The same as Example 2, except that absorbent A was replaced with the calcium carbonate-embedded chitosan microcarrier obtained in the preparation of adsorbent A in Example 1. On the fifth day of operation, the COD concentration in the water was detected to be 98 mg / L, the ammonia nitrogen concentration was 46 mg / L, and the total nitrogen concentration was 58 mg / L. On the 38th day of operation, the COD concentration in the water was detected to be 59.2 mg / L, the ammonia nitrogen concentration was 7.6 mg / L, and the total nitrogen concentration was 29.1 mg / L.

[0077] Comparative Example 5

[0078] The same as Example 2, except that absorbent A was replaced with adsorbent E from Example 1, and the microorganisms used in the preparation process were anaerobic denitrifying bacteria. On the fifth day of operation, the COD concentration in the water was detected to be 91 mg / L, the ammonia nitrogen concentration was 43 mg / L, and the total nitrogen concentration was 54 mg / L. On the 35th day of operation, the COD concentration in the water was detected to be 58.9 mg / L, the ammonia nitrogen concentration was 7.7 mg / L, and the total nitrogen concentration was 28.4 mg / L.

Claims

1. A method for storing activated sludge and quickly starting a biochemical unit, comprising the following steps: (1) Treatment of activated sludge during shutdown: before shutdown, add activated carbon and adjust the aeration volume to control the dissolved oxygen concentration to above 5 mg / L. After fully aerating and mixing the activated carbon and the mud-water mixture in the sewage treatment tank for 12 to 24 hours, stop aeration and allow it to settle naturally. Discharge the supernatant so that the MLSS of the solid matter in the remaining mud-water mixture reaches above 15 g / L. Store it in a structure equipped with aeration or stirring at room temperature. (2) Sludge storage at room temperature during shutdown: micro-aerobic storage is performed during the initial storage period, and then carbon source is added for continued storage; (3) Start-up of the biochemical unit at the start-up: At the start-up, the sludge stored in step (2) is inoculated into the sewage treatment pool, adsorbent is added, and the simmering and explosion treatment is first performed, and then actual wastewater is injected for startup; The adsorbent in step (3) is based on cross-linked chitosan embedded with calcium carbonate, on which heterotrophic bacteria are adsorbed and grown, and in the adsorbent, the heterotrophic bacteria account for 5% to 50% of the mass of the adsorbent, calculated by mass fraction; The room temperature storage in step (2) is storage under room temperature conditions; the micro-oxygen storage is to control the dissolved oxygen concentration of the storage system to 0.1 mg / L~0.5 mg / L; The first storage period in step (2) refers to the first 1 / 3 to 1 / 2 of the storage period, after which the carbon source is added and stored until the end; depending on the shutdown and maintenance period, the entire storage period is 30 to 60 days; The adsorbent in step (3) is prepared by the following method: first, preparing a cross-linked chitosan carrier embedded with calcium carbonate; adding the cross-linked chitosan carrier embedded with calcium carbonate to a heterotrophic bacterial culture system using an organic carbon source for adsorption growth, culturing until the late logarithmic growth period, and removing the solid matter and drying it to obtain the adsorbent; 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 (1), activated carbon is added before shutting down, and the aeration volume is adjusted to control the dissolved oxygen concentration to 5.5~7.0mg / L. The activated carbon and the mud-water mixture in the sewage treatment tank are fully aerated and mixed for 12~24h, and then aeration is stopped and allowed to settle naturally. The supernatant is discharged so that the MLSS of the solid matter in the remaining mud-water mixture reaches 20~25g / L, and the mixture is stored in a structure with an aeration system at room temperature.

3. The method according to claim 1, characterized in that The activated sludge described in step (1) is the activated sludge from the biochemical unit of the sewage treatment plant after the coal chemical enterprise is shut down for maintenance.

4. The method according to claim 1, wherein In the supernatant of step (1), the ammonia nitrogen concentration is 10-20 mg / L, and the COD concentration is 80-100 mg / L.

5. The method according to claim 1, wherein The amount of activated carbon added is determined so that the mass concentration in the system after addition is 100~500mg / L.

6. The method according to claim 1, characterized in that The room temperature storage temperature in step (2) is 10~35℃.

7. The method according to claim 1, characterized in that The carbon source in step (2) is at least one of glucose, methanol, acetic acid, and sodium acetate; the carbon source in step (2) is supplemented according to the COD concentration in the system increasing by 1 to 30 mg / L after addition.

8. The method according to claim 7, characterized in that The carbon source in step (2) is methanol.

9. The method according to claim 1, characterized in that In the adsorbent of step (3), the heterotrophic bacteria account for 10% to 30% of the mass of the adsorbent, calculated by mass fraction.

10. The method according to claim 1, characterized in that The heterotrophic bacteria are yeasts.

11. 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.

12. The method according to claim 11, characterized in that The yeast is Candida tropicalis.

13. The method according to claim 1, wherein In the preparation method of the adsorbent, the organic carbon source is at least one of sugars, proteins, organic acids and carbon-containing organic matter conventionally cultured for the selected heterotrophic bacteria.

14. The method according to claim 13, characterized in that In the preparation method of the adsorbent, the organic carbon source is at least one of glucose, hexose, xylose, sucrose and starch.

15. The method according to claim 1, wherein In the preparation method of the adsorbent, the organic carbon source is added so that the mass concentration in the system is 1-5 g / L.

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

17. The method according to claim 16, characterized in that In the preparation method of the adsorbent, the culture conditions of the heterotrophic bacteria are: temperature 20-30° C., pH 6.0-7.

0.

18. The method according to claim 1, wherein At the start of step (3), the stored sludge and adsorbent are inoculated at one time. The amount of adsorbent added is 50-100 mg / L according to the ratio of the mixed liquid added to the system. Then, clean water is added to make the concentration of activated sludge 4000-5000 mg / L. After inoculation, the simmering and blasting treatment is carried out for 24-60 hours. After the simmering and blasting, the supernatant with suspended debris is discharged and actual wastewater is added for startup.

19. The method according to claim 1, wherein The actual wastewater quality is: ammonia nitrogen concentration is 100~500mg / L, COD concentration is 500~1000mg / L.

20. The method according to claim 1, wherein In step (3), when the COD concentration in the effluent is below 60 mg / L, the ammonia nitrogen concentration is below 8 mg / L, and the total nitrogen is below 30 mg / L, the preserved sludge completes the rapid startup process of the system.