A method for regulating and restoring a sewage treatment system after being impacted

Abstract

The present invention discloses a method for regulating and recovering a sewage treatment system after a shock. The method comprises: when the fluctuation amplitude of the respiratory rate is less than 10% of the lower limit of the normal range for more than 60 minutes, an alarm is notified to the control system, water intake is stopped, and powdered activated carbon and a biosorbent are added to the system. The alarm is released when the respiratory rate returns to the normal range, and the addition of activated carbon is first stopped. When the effluent ammonia nitrogen concentration is lower than the emission standard limit, the addition of the biosorbent is stopped and water intake is restarted to continue operation. The system achieves rapid recovery after the shock and enters a stable operating state. The biosorbent 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 mass of the adsorbent. The method of the present invention can achieve early warning and timely eliminate the risk of shock. It does not require re-acclimation and cultivation of sludge, reduces recovery time, and ensures long-term stable operation of the system.

Description

Technical Field

[0001] The present invention belongs to the technical field of sewage treatment, and in particular relates to a method for regulating and restoring a sewage treatment system after it is impacted. Background Art

[0002] Existing wastewater treatment systems' biochemical units are frequently subjected to toxic substances or load shocks. Especially when toxic shocks exceed the system's capacity, microbial activity is suppressed or even lost, requiring re-cultivation and acclimation. This results in a long recovery time for the wastewater treatment system after shocks, and can severely impact normal production. Therefore, monitoring microbial activity is crucial. Existing operating parameters such as pH and DO are commonly used to assess changes in the system's media environment, but they cannot be used solely to characterize the working status and activity of microorganisms. If microbial activity can be detected at an early stage and timely measures taken, loss of microbial activity can be avoided.

[0003] CN103592334A discloses a biological toxicity monitoring and early warning system and monitoring method based on sequencing batch reactor. The early warning system includes a sewage system, a security filter, an activated sludge system, a sewage injection pump, a sludge injection pump, a sequencing batch reactor, a dissolved oxygen electrode and a PLC system. The monitoring method includes five stages: injection mixing, contact stirring, aeration and oxygenation, reaction monitoring, and emptying and cleaning. The early warning system adopts the principle of sequencing batch reactor, and its reaction and mixing effects are optimal. The device is completely sealed and has strong anti-interference ability. Therefore, its reaction is more efficient and the results are more accurate. Through the sequencing batch reaction method, the determination and calculation of the activated sludge respiration rate are achieved in the same reactor and using the same dissolved oxygen electrode. Compared with the continuously running reactor, it is more efficient and accurate, and avoids the system error of conventional continuous operation using multiple dissolved oxygen electrodes for monitoring. It can be widely used in online monitoring and early warning of sewage toxicity. However, this method is suitable for toxicity analysis and monitoring and early warning, and does not provide a specific solution for how to recover quickly after the impact.

[0004] CN109354160A discloses a method for chemical wastewater quality control, which includes the following specific steps: Step 1, using an OUR online measuring instrument to measure the respiration rate of the wastewater; Step 2, using an activated sludge respirometer to measure the endogenous respiration rate of the activated sludge in the aeration tank of the wastewater control system; Step 3, by comparing the respiration rates, the wastewater is divided into three categories: biodegradable wastewater, non-toxic wastewater that is difficult to degrade, and toxic wastewater; Step 4, different categories of wastewater are discharged into different treatment systems for treatment. This invention solves the problem of high cost and unstable treatment effect of the existing indiscriminate treatment of chemical wastewater by classifying the wastewater and then discharging it into different treatment systems for treatment. However, it is impossible to classify the wastewater before impact, so this method cannot solve the impact recovery problem of the sewage treatment plant.

[0005] CN102629134A discloses a control system for Orbal oxidation ditch in urban sewage treatment to resist the impact of industrial toxic pollutants. The system mainly selects pH and conductivity as indicators of comprehensive toxicity reflection and early warning based on the results of toxicity correlation analysis, determines the toxicity warning threshold based on the toxicity test analysis of activated sludge in the Orbal oxidation ditch, selects toxicity monitoring points according to the characteristics of the pipeline network, and establishes an online monitoring and wireless remote transmission system for early warning of industrial toxic pollution. On this basis, an Orbal oxidation ditch operation linkage control system is established, which is linked to the pipeline network monitoring system. By adjusting the inlet flow rate, sludge return ratio and aeration intensity, the Orbal oxidation ditch is enhanced to resist the impact of industrial toxic pollutants, maintains biological activity in the ditch, and ensures the treatment efficiency of sewage. This method is more suitable for urban sewage treatment systems with obvious water quality changes and containing toxic substances such as acids, alkalis, and heavy metals. It can realize automatic early warning, decision-making and linkage control of industrial toxic substances. However, this method still maintains biological activity by adjusting process operating parameters and cannot achieve rapid repair after impact.

[0006] Because the impact of toxic substances in sewage treatment plants is uncertain and irregular, the existing technology uses the method of adding corresponding microbial agents during the impact to resist the impact risk. However, fresh agents need to be produced and therefore cannot be replenished in time. The microbial agents stored in advance are at risk of inactivation due to not being added and used in time, and the treatment cost is additionally increased. Summary of the Invention

[0007] To address the challenges of existing technologies, the present invention provides a method for regulating and recovering a sewage treatment system after a shock. This method uses three indicators—activated sludge respiration rate (OUR), chemical oxygen demand (COD), and ammonia nitrogen concentration—to diagnose shock risks in advance. This method provides early warning, eliminates shock risks promptly, and enables rapid recovery. This method eliminates the need for re-acclimation of the sludge, reduces recovery time, and ensures long-term stable operation of the system.

[0008] A first aspect of the present invention provides a method for regulating and recovering a sewage treatment system after a shock, wherein the sewage contains ammonia nitrogen pollutants, and the shock refers to a situation in which the COD value of the biochemical unit fluctuates by no more than 20% of the normal value, while the ammonia nitrogen concentration in the sewage treatment system effluent exceeds the emission standard limit (preferably 5 mg / L). The method comprises: when the fluctuation amplitude of the respiration rate (OUR) is less than 10% (preferably 10% to 20%) of the lower limit of the normal range for more than 60 minutes, an alarm is triggered to notify a control system, water intake is stopped, and powdered activated carbon and a biosorbent are added to the system until the respiration rate (OUR) returns to the normal range, at which point the alarm is released. The addition of activated carbon is first stopped, and when the effluent ammonia nitrogen concentration is less than the emission standard limit, the addition of the biosorbent is stopped, thereby achieving rapid recovery of the shocked system and entering a stable operating state. The biosorbent is based on a cross-linked chitosan matrix embedded with calcium carbonate, on which heterotrophic bacteria are adsorbed and grown, wherein the heterotrophic bacteria account for 5% to 50%, preferably 10% to 30%, of the adsorbent.

[0009] In the present invention, the shock is caused by the increase of toxic substances that have a toxic effect on nitrifying bacteria in the system, such as oil recovery additives, heavy metal ions, cyanide and foaming agents.

[0010] In the present invention, when the normal value of the chemical oxygen demand (COD) of the biochemical unit refers to the chemical oxygen demand when the biochemical unit is operating normally and stably, if the chemical oxygen demand (COD) is allowed to operate within a certain range during normal and stable operation, the increase in COD relative to the normal value refers to the upper limit of the range, and the decrease in COD relative to the normal value refers to the lower limit of the range.

[0011] In the present invention, the normal range of the respiration rate (OUR) refers to the allowable range of the endogenous respiration rate (OUR) of the activated sludge in the aeration tank when the biochemical unit is operating normally and stably.

[0012] A second aspect of the present invention provides a method for shock diagnosis and post-shock control and recovery of a sewage treatment system, wherein the sewage contains ammonia nitrogen pollutants, and the method comprises:

[0013] (1) When the effluent from the sewage treatment system fails to meet the discharge standard requirements, the chemical oxygen demand (COD) and ammonia nitrogen concentration of the sewage treatment system are used to determine whether it is a toxic substance shock. That is, when the COD value does not change by more than 20% of the normal value and the ammonia nitrogen concentration of the effluent from the sewage treatment system is higher than the discharge standard limit (preferably, the ammonia nitrogen concentration is 5 mg / L), it is a toxic substance shock.

[0014] (2) When the sewage treatment system is impacted by toxic substances, and the fluctuation range of the respiratory rate (OUR) is less than 10% (preferably 10% to 20%) of the lower limit of the normal range and the respiratory rate returns to the value within the normal range within 30 minutes to 60 minutes, and the effluent ammonia nitrogen concentration is lower than the discharge standard limit, no measures need to be taken;

[0015] (3) When the sewage treatment system is impacted by toxic substances and the fluctuation amplitude of the respiration rate (OUR) exceeds the lower limit of the normal range by more than 10% (preferably 10% to 20%) for more than 60 minutes, an alarm is issued to the control system, water is stopped, and powdered activated carbon and biosorbent are added to the system until the respiration rate (OUR) returns to the normal range. The alarm is then lifted and the addition of activated carbon is stopped first. When the effluent ammonia nitrogen concentration is lower than the emission standard limit, the addition of biosorbent is stopped, so as to achieve rapid recovery of the impacted system and enter a stable operating state.

[0016] In the present invention, the emission standard requirements are generally requirements for COD and ammonia nitrogen concentrations, for example, the COD concentration is not greater than 40 mg / L, and the ammonia nitrogen concentration is not greater than 5 mg / L, that is, the emission standard limit COD concentration is 40 mg / L, and the ammonia nitrogen concentration is 5 mg / L.

[0017] In the present invention, the shock is caused by the increase of toxic substances that have a toxic effect on nitrifying bacteria in the system, such as oil recovery additives, heavy metal ions, cyanide and foaming agents.

[0018] In the present invention, when the normal value of the chemical oxygen demand (COD) of the biochemical unit refers to the chemical oxygen demand when the biochemical unit is operating normally and stably, if the chemical oxygen demand (COD) is allowed to operate within a certain range during normal and stable operation, the increase in COD relative to the normal value refers to the upper limit of the range, and the decrease in COD relative to the normal value refers to the lower limit of the range.

[0019] In the present invention, the normal range of the respiration rate (OUR) refers to the allowable range of the endogenous respiration rate (OUR) of the activated sludge in the aeration tank when the biochemical unit is operating normally and stably.

[0020] In the method of the present invention, the sewage of the sewage treatment system can be the wastewater of the aerobic biochemical unit after oil separation flotation pretreatment, wherein the COD is 300-1000 mg / L, the ammonia nitrogen is 100-300 mg / L, and the total nitrogen is 100-300 mg / L.

[0021] In the present invention, when the sewage treatment system is impacted by toxic substances, the activated carbon is added every 30 to 60 minutes, and each addition is performed according to the concentration of the solid-liquid mixture after addition of 30 to 50 mg / L. The biosorbent and the activated carbon are added simultaneously, and the mass ratio of the activated carbon to the biosorbent during each addition is 1:1 to 15:1, preferably 1:1 to 10:1.

[0022] In the present invention, the activated carbon is well known to those skilled in the art, and can be powdered activated carbon or coal-based crushed carbon.

[0023] In the present invention, the biosorbent is based on cross-linked chitosan embedded with calcium carbonate, on which heterotrophic bacteria are adsorbed and grown. In terms of mass fraction, the heterotrophic bacteria account for 5% to 50% of the adsorbent, preferably 10% to 30%.

[0024] In the present invention, the biosorbent 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 bacterial culture system using an organic carbon source for adsorption growth, the culture stops at the late logarithmic growth stage, and the solid matter is removed and dried to obtain the biosorbent.

[0025] In the biosorbent preparation method of the present invention, the cross-linked chitosan carrier encapsulating calcium carbonate can be obtained using conventional preparation methods in the art. Cross-linking methods include direct cross-linking and chemical modification during cross-linking. The cross-linking agent used in the direct cross-linking method includes at least one of epichlorohydrin, glutaraldehyde, formaldehyde, crown ethers, and genipin, with genipin being preferred. Cross-linking occurs between chitosan and cross-linker molecules, converting the chitosan molecules from linear chains to a network structure. Cross-linking can improve chitosan's physical properties, such as specific surface area and pore structure, and effectively enhance chitosan's stability.

[0026] In the method for preparing the biosorbent of 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.

[0027] In the biosorbent preparation method of the present invention, the organic carbon source is determined based on the specific bacterial species selected and is generally a carbon-containing organic compound such as sugars, proteins, or organic acids conventionally used in the cultivation of the selected heterotrophic bacteria. For example, the organic carbon source may be 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.

[0028] In the biosorbent preparation method of the present invention, 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 rotation speed of 200-600 rpm for shaking culture. Cultivation is continued until the late logarithmic growth phase, typically for 24-80 hours.

[0029] In the present invention, in the preparation method of the biosorbent, the drying temperature is 25-50° C., and the drying time is 1-5 hours.

[0030] In the present invention, in the method for regulating and recovering the sewage treatment system after being impacted, the operating conditions during normal stable operation are adopted, wherein the pH is 7.0-8.0 and the temperature is 25-35°C, wherein the dissolved oxygen concentration in pool A is controlled to be less than 0.5 mg / L, and the dissolved oxygen concentration in pool O is controlled to be 2-5 mg / L, and no adjustment is required.

[0031] In the present invention, the activated carbon or the biosorbent is added to the aeration tank, such as the O tank.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] (1) The present invention uses OUR, COD and ammonia nitrogen concentration as a comprehensive response and early warning indicator of the sewage treatment system, which makes it easy to realize online and timely monitoring of whether the sewage is impacted by toxic substances. The three detection indicators are linked as an early diagnostic signal, reducing the risk of impact.

[0034] (2) When the present invention encounters a serious impact of toxic substances, the water intake is first stopped. The added activated carbon can temporarily adsorb organic pollutants in the incoming water, slowing down the toxic interference of high-concentration or toxic pollutants on the microorganisms in the activated sludge. The biosorbent can intercept and quickly adsorb the microorganisms released after deflocculation, and at the same time adsorb small molecules, thereby providing nutrients for the normal growth and metabolism of microorganisms while ensuring the water quality of the effluent.

[0035] (3) The present invention adopts the synergistic effect of adding activated carbon and biological adsorbent at the same time, which can isolate high-concentration toxic substances from contact with microorganisms, realize the temporary storage of macromolecular substances and the synergistic degradation of biological enzymes, reduce the loss while ensuring biological activity, greatly shorten the recovery time, realize rapid recovery after system impact, and ensure the long-term stable operation effect of the system.

[0036] (4) The present invention uses positively charged cross-linked chitosan and heterotrophic bacteria that use organic carbon sources as dual microcarriers, which can enable nitrifying bacteria to be adsorbed on the dual microcarriers for rapid growth. At the same time, in the case of nutrient deficiency or insufficient conditions, the heterotrophic bacteria will gradually release binding sites to the nitrifying bacteria, which can further increase the density of nitrifying bacteria and thus achieve rapid recovery of the system's nitrification function. 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] In the present invention, COD concentration is determined according to GB11914-89 "Water quality - Determination of chemical oxygen demand - Dichromate method"; ammonia nitrogen concentration is determined according to GB7478-87 "Water quality - Determination of ammonium - Distillation and titration method"; and total nitrogen concentration is determined according to GB11894-89 "Water quality - Determination of total nitrogen - Alkaline potassium persulfate digestion ultraviolet spectrophotometry."

[0039] 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.

[0040] The respiration rate of the present invention is measured online by an activated sludge respirometer, COD is measured by a chemical oxygen demand online analyzer, and ammonia nitrogen is measured by a Hach online analyzer.

[0041] Example 1

[0042] Preparation of adsorbent

[0043] 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.

[0044] 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.

[0045] Compared with the preparation method of adsorbent A, other conditions remain unchanged, and the only difference is that a Lactobacillus culture system using glucose is used instead of a Candida tropicalis culture system using xylose to prepare adsorbent B.

[0046] Compared with the preparation method of adsorbent A, other conditions remain unchanged, and the only difference is that a Desulfuromonas culture system using sucrose is used instead of a Candida tropicalis culture system using xylose to prepare adsorbent C.

[0047] Compared with the preparation method of adsorbent A, other conditions remained unchanged, and the only difference was that during the preparation of chitosan, genipin was replaced with 10 mL of 25% glutaraldehyde. After adding 10 mL of 25% glutaraldehyde, stirring was continued for 2 hours. After adding 5 g of sodium borohydride and reacting for 2 hours, the mixture was centrifuged and precipitated to prepare adsorbent D.

[0048] Compared with the preparation method of adsorbent A, other conditions remain unchanged, and the only difference is that during the carrier preparation process, only chitosan is added without adding heterotrophic microorganisms, and adsorbent E is prepared.

[0049] Compared with the preparation method of adsorbent A, other conditions remain unchanged, and the only difference is that the culture system of heterotrophic denitrifying bacteria is used instead of the culture system of tropical yeast to prepare adsorbent F.

[0050] Table 1 Preparation of adsorbent

[0051] 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 none none Adsorbent F Join Kinipen Heterotrophic denitrifying bacteria Xylose 15％

[0052] Example 2

[0053] The laboratory constructed a small, 50-liter AO unit to conduct shock-controlled recovery experiments. During normal operation, the treated wastewater quality was: COD concentration of 300-350 mg / L, ammonia nitrogen concentration of 100-150 mg / L, and total nitrogen concentration of 100-180 mg / L. After treatment, the effluent pollutant concentrations were all below the standard discharge limits of 40 mg / L for COD and 5 mg / L for ammonia nitrogen. Operating conditions were a pH of 7.3-7.8 and a temperature of 30-33°C. The dissolved oxygen concentration in Tank A was controlled to less than 0.5 mg / L, and in Tank O to 3-4 mg / L. After adding a small amount of oil recovery additive to the wastewater, the effluent failed to meet the above-mentioned discharge requirements. At this time, the COD concentration in the wastewater increased to 360 mg / L. After 24 hours of operation, the effluent ammonia nitrogen concentration reached 18 mg / L. The respiration rate (OUR) in the sewage treatment system gradually decreased. When it dropped below 10% of the lower limit of the normal range for more than 60 minutes, the control system automatically alarmed and stopped the water intake. The other process operating conditions remained unchanged. The activated carbon dosing device and the biosorbent dosing device were promptly started to add activated carbon and adsorbent A to the O tank. The activated carbon was added in an amount based on the solid-liquid mixture concentration of 50 mg / L after addition, and the mass ratio of activated carbon to biosorbent was 10:1. The dosing device was started every 60 minutes to add activated carbon and adsorbent once according to the above dosage. After two consecutive additions, the time from when the respiration rate OUR exceeded the lower limit of the normal range by 10% to gradually returning to the normal range was 150 minutes. At this time, the ammonia nitrogen concentration was 12 mg / L. Thereafter, the addition of activated carbon was stopped and only biological adsorbent A was added. After the system continued to run for 120 minutes, the ammonia nitrogen concentration was analyzed to be 4.6 mg / L. Thereafter, the addition of biological adsorbent A was stopped and water was continued to be fed in. After the shock, it took 270 minutes to achieve rapid recovery and entered a stable operating state.

[0054] Example 3

[0055] The laboratory constructed a small, 50-liter AO unit to conduct shock-controlled recovery experiments. During normal operation, the treated wastewater quality was: COD concentration of 300-350 mg / L, ammonia nitrogen concentration of 100-150 mg / L, and total nitrogen concentration of 100-180 mg / L. After treatment, the effluent pollutant concentrations were all below the standard discharge limits of 40 mg / L for COD and 5 mg / L for ammonia nitrogen. Operating conditions were a pH of 7.3-7.8 and a temperature of 30-33°C. The dissolved oxygen concentration in Tank A was controlled to less than 0.5 mg / L, and in Tank O to 3-4 mg / L. After adding a small amount of oil recovery additive to the wastewater, the effluent failed to meet the above-mentioned discharge requirements. At this time, the COD concentration in the wastewater increased to 378 mg / L. After 24 hours of operation, the effluent ammonia nitrogen concentration reached 20 mg / L. The respiration rate (OUR) in the sewage treatment system gradually decreased. When it fell below 10% of the lower limit of the normal range for more than 60 minutes, the control system automatically alarmed and stopped the water intake. The other process operating conditions remained unchanged. The activated carbon dosing device and the biosorbent dosing device were promptly started to add activated carbon and adsorbent B to the O tank. The activated carbon was added at a solid-liquid mixture concentration of 50 mg / L after addition, and the mass ratio of activated carbon to biosorbent was 10:1. The dosing device was started every 60 minutes to add activated carbon and adsorbent once according to the above dosage. After two consecutive additions, the time from when the respiration rate OUR exceeded the lower limit of the normal range by 10% to gradually returning to the normal range was 155 minutes. At this time, the ammonia nitrogen concentration was 12 mg / L. Thereafter, the addition of activated carbon was stopped and only biological adsorbent B was added. After the system continued to run for 140 minutes, the ammonia nitrogen concentration was analyzed to be 4.6 mg / L. Thereafter, the addition of biological adsorbent B was stopped and water was continued to be fed in. After the shock, it took 295 minutes to achieve rapid recovery and entered a stable operating state.

[0056] Example 4

[0057] The laboratory constructed a small, 50-liter AO unit to conduct shock-controlled recovery experiments. During normal operation, the treated wastewater quality was: COD concentration of 300-350 mg / L, ammonia nitrogen concentration of 100-150 mg / L, and total nitrogen concentration of 100-180 mg / L. After treatment, the effluent pollutant concentrations were all below the standard discharge limits of 40 mg / L for COD and 5 mg / L for ammonia nitrogen. Operating conditions were a pH of 7.3-7.8 and a temperature of 30-33°C. The dissolved oxygen concentration in Tank A was controlled to less than 0.5 mg / L, and in Tank O to 3-4 mg / L. After adding a small amount of oil recovery additive to the wastewater, the effluent failed to meet the above-mentioned discharge requirements. At this time, the COD concentration in the wastewater increased to 360 mg / L. After 24 hours of operation, the effluent ammonia nitrogen concentration reached 18 mg / L. The respiration rate (OUR) in the sewage treatment system gradually decreased. When it dropped below 10% of the lower limit of the normal range for more than 60 minutes, the control system automatically alarmed and stopped the water intake. The other process operating conditions remained unchanged. The activated carbon dosing device and the biosorbent dosing device were promptly started to add activated carbon and adsorbent C to the O tank. The activated carbon was added in an amount based on a solid-liquid mixture concentration of 50 mg / L after addition, and the mass ratio of activated carbon to biosorbent was 10:1. The dosing device was started every 60 minutes to add activated carbon and adsorbent once according to the above dosage. After two consecutive additions, the time from when the respiration rate OUR exceeded the lower limit of the normal range by 10% to gradually returning to the normal range was 150 minutes. At this time, the ammonia nitrogen concentration was 12 mg / L. Thereafter, the addition of activated carbon was stopped and only biological adsorbent C was added. After the system continued to run for 130 minutes, the ammonia nitrogen concentration was analyzed to be 4.6 mg / L. Thereafter, the addition of biological adsorbent C was stopped and water was continued to be fed in. After the shock, it took 280 minutes to achieve rapid recovery and entered a stable operating state.

[0058] Example 5

[0059] The laboratory constructed a small, 50-liter AO unit to conduct shock-controlled recovery experiments. During normal operation, the treated wastewater quality was: COD concentration of 300-350 mg / L, ammonia nitrogen concentration of 100-150 mg / L, and total nitrogen concentration of 100-180 mg / L. After treatment, the effluent pollutant concentrations were all below the standard discharge limits of 40 mg / L for COD and 5 mg / L for ammonia nitrogen. Operating conditions were a pH of 7.3-7.8 and a temperature of 30-33°C. The dissolved oxygen concentration in Tank A was controlled to less than 0.5 mg / L, and in Tank O to 3-4 mg / L. After adding a small amount of oil recovery additive to the wastewater, the effluent failed to meet the above-mentioned discharge requirements. At this time, the COD concentration in the wastewater increased to 360 mg / L. After 24 hours of operation, the effluent ammonia nitrogen concentration reached 18 mg / L. The respiration rate (OUR) in the sewage treatment system gradually decreased. When it fell below 10% of the lower limit of the normal range for more than 60 minutes, the control system automatically alarmed and stopped the water intake. The other process operating conditions remained unchanged. The activated carbon dosing device and the biosorbent dosing device were promptly started to add activated carbon and adsorbent D to the O tank. The activated carbon was added at a solid-liquid mixture concentration of 50 mg / L after addition, and the mass ratio of activated carbon to biosorbent was 10:1. The dosing device was started every 60 minutes to add activated carbon and adsorbent once according to the above dosage. After two consecutive additions, the time from when the respiration rate OUR exceeded the lower limit of the normal range by 10% to gradually returning to the normal range was 155 minutes. At this time, the ammonia nitrogen concentration was 12 mg / L. Thereafter, the addition of activated carbon was stopped and only biological adsorbent D was added. After the system continued to run for 130 minutes, the ammonia nitrogen concentration was analyzed to be 4.6 mg / L. Thereafter, the addition of biological adsorbent D was stopped and water was continued to be fed in. After the shock, it took 285 minutes to achieve rapid recovery and entered a stable operating state.

[0060] Example 6

[0061] The experimental apparatus and wastewater treatment were the same as in Example 2, except that the activated carbon dosage was such that the solid-liquid mixture concentration after addition was 40 mg / L, and the mass ratio of activated carbon to biosorbent was 5:1. The dosing device was activated every 60 minutes. After two consecutive additions, the time from when the respiration rate (OUR) exceeded the lower limit of the normal range by 10% to its gradual return to the normal range was 175 minutes, at which point the ammonia nitrogen concentration was 8 mg / L. Thereafter, activated carbon addition was stopped and only biosorbent A was added. After 100 minutes of continued operation, the system showed an ammonia nitrogen concentration of 4.9 mg / L. Biosorbent A addition was then stopped, and water was allowed to flow again. After 275 minutes of post-shock, the system experienced a rapid recovery and entered a stable operating state.

[0062] Example 7

[0063] The experimental apparatus and treated wastewater were the same as those in Example 2, except that in order to verify the degree of impact, a small amount of other refinery wastewater was mixed into the wastewater to increase the COD concentration to 360 mg / L. During the operation of the device, the respiration rate (OUR) of the activated sludge gradually decreased. After falling to 10% below the lower limit of the normal range, the respiration rate continued to operate for 40 minutes and returned to the value within the normal range. Within the next 24 hours of operation, there were six fluctuations in the respiration rate, which decreased and recovered within 60 minutes. In addition, the effluent ammonia nitrogen concentration did not fluctuate much, always between 3 and 5 mg / L. It can be seen that the system itself has a certain self-recovery ability, and no measures need to be taken.

[0064] Comparative Example 1

[0065] The experimental apparatus and wastewater treatment were the same as in Example 2, except that when the effluent ammonia nitrogen concentration reached 18 mg / L and the respiration rate (OUR) in the wastewater treatment system gradually fell below 10% of the lower limit of the normal range for more than 60 minutes, the control system automatically issued an alarm. At this point, the system automatically stopped water intake and activated the biosorbent dosing device to add adsorbent A to the O tank at a solid-liquid mixture concentration of 5 mg / L after addition. The dosing device was activated every 60 minutes to add adsorbent. After four consecutive additions, the respiration rate (OUR) remained below 10% of the lower limit of the normal range. After 270 minutes of post-shock, the system had not yet achieved a rapid recovery, with the effluent ammonia nitrogen concentration still as high as 11 mg / L. After two days of continued operation, the activated sludge respiration rate (OUR) was within the normal range, and the effluent ammonia nitrogen concentration was 3.4 mg / L. The system had essentially returned to normal, and continuous water intake was resumed.

[0066] Comparative Example 2

[0067] The experimental device and the wastewater treatment were the same as in Example 2, except that when the effluent ammonia nitrogen concentration was as high as 18 mg / L, the respiration rate (OUR) in the sewage treatment system gradually decreased by 10% of the lower limit of the normal range for more than 60 minutes, and the control system automatically alarmed. At this time, the system automatically stopped the water intake and started the activated carbon dosing device to add activated carbon to the O pool according to the solid-liquid mixture concentration of 50 mg / L after addition. The dosing device was started every 60 minutes to add activated carbon. After 4 consecutive additions, the respiration rate OUR was still 10% lower than the lower limit of the normal range. After 270 minutes after the shock, the system did not achieve rapid recovery, and the effluent ammonia nitrogen was still as high as 17 mg / L. After continuing to run for 1 day, the activated sludge respiration rate OUR was within the normal range, but the effluent ammonia nitrogen concentration was still 12 mg / L. After continuing to run for 2 days, the system basically returned to normal, with the effluent ammonia nitrogen concentration being 4.2 mg / L, and the water intake was started for continuous operation.

[0068] Comparative Example 3

[0069] The experimental apparatus and wastewater treatment were the same as in Example 2, except that adsorbent E was added after the system was impacted. The activated carbon was added at a concentration of 50 mg / L for the solid-liquid mixture after addition, and the mass ratio of activated carbon to biosorbent was 10:1. The dosing device was activated every 60 minutes and the above dosage was added once. After four consecutive additions, the respiration rate (OUR) remained below 10% of the lower limit of the normal range. After 270 minutes after the impact, the system had not yet achieved rapid recovery, with the effluent ammonia nitrogen concentration still as high as 13 mg / L. After two days of operation, the activated sludge respiration rate (OUR) was within the normal range, and the effluent ammonia nitrogen concentration was 9.4 mg / L. After another two days of operation, the system essentially returned to normal, with the effluent ammonia nitrogen concentration reaching 3.5 mg / L. Continuous influent operation was initiated.

[0070] Comparative Example 4

[0071] The experimental apparatus and wastewater treatment were the same as in Example 2, except that adsorbent F was added after the system was impacted. The activated carbon was added at a concentration consistent with a solid-liquid mixture of 50 mg / L, and the mass ratio of activated carbon to biosorbent was 10:1. The dosing device was activated every 60 minutes, and the above dosage was added once. After four consecutive additions, the respiration rate (OUR) remained below 10% of the lower limit of the normal range. 270 minutes after the impact, the system had not yet achieved rapid recovery, with effluent ammonia nitrogen still as high as 15 mg / L. After two days of continued operation, the activated sludge respiration rate (OUR) was within the normal range, and the effluent ammonia nitrogen concentration was 10.7 mg / L. After another two days of operation, the system essentially returned to normal, with an effluent ammonia nitrogen concentration of 4.5 mg / L. Continuous influent operation was initiated.

[0072] Comparative Example 5

[0073] The experimental apparatus and wastewater treatment were the same as in Example 2, except that the mass ratio of activated carbon to biosorbent was 20:1. The dosing device was activated every 60 minutes, and the above dosages were added. After four consecutive additions, the respiration rate (OUR) remained below 10% of the lower limit of the normal range. After 270 minutes from the shock, the system had not yet achieved rapid recovery, with the effluent ammonia nitrogen concentration still as high as 15 mg / L. After two days of operation, the activated sludge respiration rate (OUR) was within the normal range, and the effluent ammonia nitrogen concentration was 7.2 mg / L. After one day of operation, the system essentially returned to normal, with the effluent ammonia nitrogen concentration reaching 4.1 mg / L. Continuous operation with influent was initiated.

Claims

1. A method for regulating and restoring a sewage treatment system after a shock, wherein: The sewage contains ammonia nitrogen pollutants. The shock refers to when the COD value of the biochemical unit does not change by more than 20% of the normal value, but the ammonia nitrogen concentration in the sewage treatment system effluent is higher than the emission standard limit. The control and recovery method includes: when the fluctuation range of the respiration rate OUR is lower than the lower limit of the normal range by more than 10% for more than 60 minutes, an alarm is notified to the control system, water intake is stopped, and powdered activated carbon and a biosorbent are added to the system until the respiration rate OUR returns to the normal range, the alarm is lifted, and the addition of activated carbon is stopped first. When the ammonia nitrogen concentration in the effluent is lower than the emission standard limit, the addition of the biosorbent is stopped, thereby achieving rapid recovery of the shock system and entering a stable operating state. The biosorbent 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 adsorbent mass. The mass ratio of activated carbon to biosorbent is 1:1~15:1 each time it is added; The heterotrophic bacteria are at least one of yeast, lactic acid bacteria, and sulfate-reducing bacteria; The biosorbent 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 stops at the late logarithmic growth stage, and the solid matter is taken out and dried to obtain the biosorbent.

2. The method according to claim 1, characterized in that In the control recovery method, when the fluctuation amplitude of the respiratory rate OUR is lower than the lower limit of the normal range by 10% to 20% for more than 60 minutes, an alarm is notified to the control system.

3. The method according to claim 1, characterized in that In the biosorbent, heterotrophic bacteria account for 10% to 30% of the mass of the biosorbent.

4. The method according to claim 1, wherein The shock is caused by an increase in toxic substances that have a toxic effect on nitrifying bacteria in the system.

5. A method for shock diagnosis and post-shock control and recovery of a sewage treatment system, wherein: The sewage contains ammonia nitrogen pollutants, and the method includes: (1) When the effluent from the sewage treatment system fails to meet the discharge standard requirements, the chemical oxygen demand (COD) and ammonia nitrogen concentration of the sewage treatment system are used to determine whether it is a toxic substance shock. That is, when the COD value does not change by more than 20% of the normal value and the ammonia nitrogen concentration of the effluent from the sewage treatment system is higher than the discharge standard limit, it is a toxic substance shock. (2) When the sewage treatment system is impacted by toxic substances, and the fluctuation range of the respiration rate OUR is less than 10% of the lower limit of the normal range and the respiration rate returns to the value within the normal range within 30 minutes to 60 minutes, and the effluent ammonia nitrogen concentration is lower than the discharge standard limit, no measures need to be taken; (3) When the sewage treatment system is impacted by toxic substances and the fluctuation amplitude of the respiration rate OUR exceeds 10% of the lower limit of the normal range for more than 60 minutes, an alarm is notified to the control system, water is stopped, and powdered activated carbon and biological adsorbent are added to the system until the respiration rate OUR returns to the normal range. The alarm is lifted and the addition of activated carbon is stopped first. When the ammonia nitrogen concentration in the effluent is lower than the emission standard limit, the addition of biological adsorbent is stopped to achieve rapid recovery of the impact system and enter a stable operating state. The mass ratio of activated carbon to biological adsorbent is 1:1 to 15:1 each time the activated carbon is added. The biological adsorbent 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 mass of the adsorbent. The heterotrophic bacteria are at least one of yeast, lactic acid bacteria, and sulfate-reducing bacteria. The biosorbent 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 stops at the late logarithmic growth stage, and the solid matter is taken out and dried to obtain the biosorbent.

6. The method according to claim 5, characterized in that In step (2), when the sewage treatment system is impacted by toxic substances, and the fluctuation range of the respiration rate OUR is lower than 10%~20% of the lower limit of the normal range and the respiration rate returns to the value within the normal range within 30min~60min, and the effluent ammonia nitrogen concentration is lower than the emission standard limit, no measures need to be taken.

7. The method according to claim 5, characterized in that In step (3), when the sewage treatment system is impacted by toxic substances and the fluctuation range of the respiratory rate OUR exceeds 10% to 20% of the lower limit of the normal range for more than 60 minutes, an alarm is notified to the control system.

8. The method according to claim 1 or 5, characterized in that The sewage from the sewage treatment system is the wastewater from the aerobic biochemical unit after oil separation flotation pretreatment, with COD of 300~1000mg / L, ammonia nitrogen of 100~300mg / L, and total nitrogen of 100~300mg / L.

9. The method according to claim 1 or 5, characterized in that When the sewage treatment system is impacted by toxic substances, the activated carbon is added every 30 to 60 minutes, and each time it is added according to the concentration of the solid-liquid mixture after addition of 30 to 50 mg / L. The biological adsorbent and the activated carbon are added at the same time, and the mass ratio of the activated carbon to the biological adsorbent is 1:1 to 10:1 each time.

10. The method according to claim 1 or 5, characterized in that The heterotrophic bacteria are yeasts; the yeasts are selected from at least one of Candida, Cryptococcus, Hansenula, Pichia pastoris, Rhodotorula, Torulopsis or Trichosporon.

11. The method according to claim 10, characterized in that The yeast is Candida tropicalis.

12. The method according to claim 1 or 5, characterized in that The lactic acid bacteria are selected from at least one of Lactobacillus, Bifidobacterium and Lactococcus; the sulfate-reducing bacteria are selected from at least one of Desulfomonas and Desulfuromyces.

13. The method according to claim 1 or 5, characterized in that The organic carbon source is at least one of sugars, proteins and organic acids used in conventional culture of the selected heterotrophic bacteria. The organic carbon source is added according to a mass concentration of 1-5 g / L in the system after addition.

14. The method according to claim 1 or 5, characterized in that The culture conditions of the heterotrophic bacteria are: temperature 20-38°C, pH 6.0-8.5; static fermentation or shaking culture, stirring every 30-60 minutes for static fermentation culture, and a shaking culture speed of 200-600 r / min.

15. The method according to claim 14, characterized in that The culture conditions of the heterotrophic bacteria are: temperature 20-30° C., pH 6.0-7.

0.

16. The method according to claim 1 or 5, characterized in that: The drying temperature is 25~50℃ and the drying time is 1~5h.