Emergency control method for micro-filament type sludge bulking

Abstract

This invention relates to an emergency control method for microfilamentous sludge bulking, comprising the following steps: Chemical dosing: Chemicals are added to the returned sludge according to a first predetermined process; Process monitoring: Monitoring is performed at the end of each dosing cycle, with monitoring indicators including but not limited to total effluent quality, settling performance of the mixed liquor in the biological treatment tank, and microscopic examination of the mixed liquor at the biological treatment tank effluent outlet; If the last monitoring indicator in S2 is qualified, the chemical dosing is terminated; If the last monitoring indicator in S2 is unqualified, the second stage of chemical dosing in the returned sludge is initiated: Chemicals are added to the returned sludge according to a second predetermined process. Its beneficial effects are: significantly shortening the time required to inhibit microfilamentous sludge bulking; lowering the technical application threshold, as this technical solution can be immediately implemented under the existing wastewater treatment process conditions without additional adjustments to process conditions and parameters, ensuring controllable implementation risks and facilitating widespread application.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to an emergency control method for microfilamentous sludge bulking. Background Technology

[0002] Sludge bulking is a common phenomenon in wastewater treatment systems utilizing activated sludge processes, particularly in Biological Nutrient Removal (BNR) systems with alternating anaerobic / anoxic / aerobic environments. Among the causes of sludge bulking, microfilamentous sludge bulking exhibits a significantly higher incidence in winter and spring than in summer and autumn, making it a major contributing factor to sludge bulking in BNR systems. This seasonality also aligns with the timing patterns of sludge bulking in most wastewater treatment plants in China. Sludge bulking leads to difficulties in sludge-water separation, thereby affecting effluent quality.

[0003] Currently, sludge bulking control methods and technologies include: load adjustment, process mode adjustment, coagulant dosing, and disinfectant dosing. Among these, load adjustment and process mode adjustment are slow and time-consuming, unable to provide rapid emergency treatment for sludge bulking. Coagulant dosing offers good short-term results and a short cycle, but it only treats the symptoms, not the root cause. Therefore, the condition often returns to normal after dosing is stopped, and continuous dosing can easily cause equipment failure and blockage, failing to achieve stable control. Disinfectant dosing technology can kill microfilamentous hyphae and restore the normal settling properties of sludge flocs, making it a relatively ideal emergency control method for microfilamentous sludge bulking. However, existing disinfectant dosing technologies require the purchase and installation of auxiliary instruments, or their application is limited by the hardware conditions of wastewater treatment plants. Furthermore, rapid response and emergency control are difficult to achieve for microfilamentous sludge bulking. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides an emergency control method for microfilamentous sludge bulking, which solves the problems of poor applicability of the existing emergency control methods for microfilamentous sludge bulking in different treatment plants, high equipment modification costs, and difficulty in realizing rapid response and emergency control technology for microfilamentous sludge bulking.

[0006] (II) Technical Solution

[0007] To achieve the above objectives, the main technical solutions adopted by the present invention include:

[0008] In a first aspect, embodiments of the present invention provide an emergency control method for microfilamentous sludge bulking, comprising the following steps:

[0009] S1. Chemical dosing: Add chemicals to the return sludge according to the first set procedure;

[0010] S2. Process monitoring: Monitoring shall be carried out once at the end of each dosing cycle. The monitoring indicators include, but are not limited to, total effluent quality, sedimentation performance of mixed liquor in biological treatment tank, and microscopic examination of mixed liquor at the outlet of biological treatment tank.

[0011] S3. If the last monitoring indicator in S2 is qualified, the dosing of the reagent ends; if the last monitoring indicator in S2 is not qualified, the second stage of adding reagent to the return sludge is started: add reagent to the return sludge according to the second set procedure.

[0012] As a preferred embodiment of the present invention, the emergency control method for microfilamentous sludge bulking uses a chlorine-containing disinfectant with an effective chlorine content of 10-15%.

[0013] As a preferred embodiment of the present invention, in the emergency control method for microfilamentous sludge bulking, in S1, the first set process lasts for a total of 15 days, and the specific process is as follows: On the first day, a dose of 3g Cl / kg MLSS of available chlorine is used.

[0014] From day 2 to day 7, a maintenance dose of 2 g Cl / kg MLSS of available chlorine was used.

[0015] On days 8-15, the overall effluent quality is assessed. If the overall effluent quality remains stable, the maintenance dose of available chlorine is increased to 4 g Cl / kg MLSS. If the overall effluent quality fluctuates, the maintenance dose of available chlorine is continued at 2 g Cl / kg MLSS until the overall effluent quality stabilizes, at which point the maintenance dose of available chlorine is increased to 4 g Cl / kg MLSS.

[0016] As a preferred embodiment of the present invention, in the emergency control method for microfilamentous sludge bulking, if the second stage of reagent addition is initiated in S3, the second round of process monitoring is carried out simultaneously with reference to S2. The specific process of the second set process is as follows: On the first day, a dose of 6g Cl / kg MLSS effective chlorine is used.

[0017] From day 2 to day 6, a maintenance dose of 3 g Cl / kg MLSS of available chlorine was used.

[0018] If the monitoring indicators are within acceptable limits after the 6th day, the drug administration will be discontinued.

[0019] As a preferred embodiment of the present invention, in the emergency control method for microfilamentous sludge bulking, in S3, if the monitoring indicators fail to meet the standards after day 6 in the second set process, the second set process still needs to continue adding reagents. The specific process is as follows: from day 7 to day 15, the total effluent water quality is judged. If the total effluent water quality remains stable, the maintenance dose of effective chlorine is increased to 4 g Cl / kg MLSS; if the total effluent water quality fluctuates, the maintenance dose of effective chlorine is continued at 3 g Cl / kg MLSS until the total effluent water quality stabilizes, and then the maintenance dose of effective chlorine is increased to 4 g Cl / kg MLSS.

[0020] As a preferred embodiment of the present invention, in the emergency control method for microfilamentous sludge bulking, in S3, if the process monitoring indicators are qualified during the 7th to 15th days of the second set process, the dosing of the reagent is stopped.

[0021] As a preferred embodiment of the present invention, the emergency control method for microfilamentous sludge bulking involves adding the agent to the returned sludge at either the outlet of the sludge return pump or the sludge return channel.

[0022] As a preferred embodiment of the present invention, the emergency control method for microfilamentous sludge bulking involves three dosing cycles per day, with dosing for 3-5 hours and stopping for 3-5 hours in each cycle.

[0023] In a preferred embodiment of the present invention, the emergency control method for microfilamentous sludge bulking uses a mixture of disinfectant and coagulant as the agent.

[0024] The dosage of the agent is referenced from that in other embodiments. In addition, the dosage of the coagulant is 5-500 mg coagulant / kg MLSS. The coagulant is selected from one or more of polyaluminum chloride, aluminum sulfate, ferric chloride and polyacrylamide.

[0025] As a preferred embodiment of the present invention, in the emergency control method for microfilamentous sludge bulking, S2, the total effluent water quality monitoring includes COD, TN, TP, and ammonia nitrogen;

[0026] The settling performance of the mixed liquor in the biological treatment tank is the same as the settling ratio of the mixed liquor in the aeration tank after 30 minutes.

[0027] Microscopic examination of the mixed liquor at the effluent outlet of the biological treatment tank includes changes in mycelium, the state of sludge flocs, and the transparency of interstitial water.

[0028] (III) Beneficial Effects

[0029] The beneficial effects of this invention are as follows: The emergency control method for microfilamentous sludge bulking of this invention involves directly adding the agent to the returned sludge. The agent enters the biological treatment tank along with the returned sludge, thereby inhibiting microfilamentous sludge bulking in the biological treatment tank. Simultaneously, process monitoring is implemented during agent addition, allowing for timely adjustments to the agent dosage and total dosing time based on the current state of the mixed liquor in the biological treatment tank. Compared to existing technologies, this method achieves emergency control of microfilamentous sludge bulking in wastewater treatment plants without requiring additional instruments or production reduction / shutdown. It also allows for reasonable control of agent dosage and total dosing time, improving treatment efficiency and significantly shortening the time required to inhibit microfilamentous sludge bulking. Furthermore, it lowers the technical application threshold, as this technical solution can be implemented immediately under the existing wastewater treatment process conditions without additional adjustments to process conditions and parameters. The implementation risks are controllable, facilitating widespread application.

[0030] The agent is a chlorine-containing disinfectant with an effective chlorine content of 10-15%. The chlorine-containing disinfectant can kill microfilamentous hyphae and restore the normal settling performance of sludge flocs.

[0031] The first set-up process lasts 15 days. On day 1, a dosage of 3g Cl / kg MLSS of available chlorine is used. This higher dosage stimulates the filamentous bacteria in the sludge system, causing their hyphae to break down, without inhibiting nitrifying bacteria in the biological treatment tank. From day 2 to day 7, a maintenance dosage of 2g Cl / kg MLSS of available chlorine is used to primarily inhibit the growth of filamentous bacteria, while simultaneously acclimating the system's functional bacteria to the disinfectant. From day 8 to day 15, the overall effluent quality is assessed. If the overall effluent quality remains stable, the maintenance dosage of available chlorine is increased to 4g Cl / kg MLSS. If the overall effluent quality fluctuates, the maintenance dosage of 2g Cl / kg MLSS is continued until the overall effluent quality stabilizes, at which point the maintenance dosage is increased to 4g Cl / kg MLSS. The overall effluent quality is monitored to ensure rapid and effective killing of hyphae while maintaining the overall effluent quality (reflecting the stability of the water treatment system) and without affecting normal water treatment operations.

[0032] After the first phase of treatment, if the monitoring indicators fail to meet the standards, the second phase is initiated by adding the agent to the returned sludge. On day 1, a dosage of 6g Cl / kg MLSS of available chlorine is used. The second phase begins by increasing the initial dosage to enhance the effect of killing microfilamentous mycelia. From day 2 to 6, a maintenance dosage of 3g Cl / kg MLSS of available chlorine is used. This phase still aims to inhibit the growth of filamentous bacteria, while simultaneously acclimating and enhancing the tolerance of the system's functional bacteria to the disinfectant.

[0033] If the monitoring indicators fail to meet the standards after day 6 in the second set-line procedure, the second set-line procedure needs to continue adding chemicals. From day 7 to 15, the overall effluent quality is assessed. If the overall effluent quality remains stable, the maintenance dose of available chlorine is increased to 4 g Cl / kg MLSS. If the overall effluent quality fluctuates, the maintenance dose of available chlorine is continued at 3 g Cl / kg MLSS until the overall effluent quality stabilizes, at which point the maintenance dose is increased to 4 g Cl / kg MLSS. Monitoring the overall effluent quality ensures rapid and effective eradication of mycelia while maintaining overall effluent quality, without affecting normal water treatment operations. If the process monitoring indicators are satisfactory during days 7 to 15, the chemical addition can be stopped at any time. Dynamic process monitoring allows for timely adjustments to the dosing strategy, providing flexibility.

[0034] The optimal location for adding chemicals to the returned sludge is either the outlet of the sludge return pump or the sludge return channel. These two locations offer good hydraulic mixing, ensuring even distribution of the chemicals to the biological treatment tank, and are also easy to operate. The sludge return pump outlet is the preferred location.

[0035] The dosing is divided into 3 cycles per day. During each cycle, the dosing is carried out for 3-5 hours and then stopped for 3-5 hours to ensure the dosing time, thereby stimulating the filamentous bacteria in the sludge system to break down their hyphae.

[0036] The agent is a mixture of disinfectant and coagulant. The coagulant assists the disinfectant in improving the settling performance of sludge and synergistically improves the efficiency of the disinfectant in treating sludge bulking.

[0037] Microscopic examination of the mixed liquor at the effluent outlet of the biological treatment tank includes changes in mycelium, sludge floc state, and interstitial water transparency. By monitoring changes in mycelium during the process, the effectiveness of mycelium killing can be determined to adjust the dosing strategy. Combining sludge floc state and interstitial water transparency, healthy sludge flocs indicate that the microbial community is in an active state, which is conducive to the degradation of pollutants. Higher interstitial water transparency reflects the stability of water quality and helps indicate whether the wastewater treatment system is operating normally. Attached Figure Description

[0038] Figure 1 This is a microscopic image magnified 100x under a microscope of the mixed liquor at the outlet of the biological treatment tank where microfilamentous sludge bulking occurred in Example 1 of the present invention.

[0039] Figure 2 This is a microscopic image, magnified 400 times, of the mixed liquor at the outlet of the biological treatment tank in Example 1 of the present invention, showing the microfilamentous sludge bulking.

[0040] Figure 3 These are microscopic images, magnified 400x, of the mixed liquid at the outlet of the biochemical tank after different days following the addition of the reagent in Example 1 of this invention.

[0041] Figure 4These are images of the mixed liquor sludge settling at the two outlets of the biochemical tank at different times after the addition of the reagent in Example 1 of this invention. Detailed Implementation

[0042] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] This invention proposes an emergency control method for microfilamentous sludge bulking, addressing the shortcomings of existing methods such as limited applicability across different treatment plants, high equipment modification costs, and difficulty in achieving rapid response and emergency control for sludge bulking. By directly adding the reagent to the returned sludge, the reagent enters the biological treatment tank along with the returned sludge, thereby inhibiting microfilamentous sludge bulking in the biological treatment tank. Simultaneously, process monitoring is implemented during reagent addition, allowing for timely adjustments to the reagent dosage and total dosing time based on the current state of the mixed liquor in the biological treatment tank. Compared to existing technologies, this method achieves emergency control of microfilamentous sludge bulking in wastewater treatment plants without requiring additional instruments or production reduction / shutdown; it rationally controls the reagent dosage and total dosing time, improving treatment efficiency and significantly shortening the time required to inhibit microfilamentous sludge bulking; and it lowers the technical application threshold, as this solution can be immediately implemented under the existing wastewater treatment process conditions without additional adjustments to process conditions and parameters, ensuring controllable implementation risks and facilitating widespread application.

[0044] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present invention can be understood more clearly and thoroughly, and that the scope of the present invention can be fully conveyed to those skilled in the art.

[0045] Example 1

[0046] This embodiment provides an emergency control method for microfilamentous sludge bulking. Taking wastewater treatment plant A as an example, the specific steps are as follows:

[0047] (1) After discovering sludge bulking in the biological treatment tank of Wastewater Treatment Plant A, refer to Figure 1 and Figure 2 In the mixed liquor at the outlet of the biological treatment tank, the filamentous bacteria in the image are Gram-positive, exhibiting a coiled, unbranched hyphae morphology. Most hyphae extend beyond the sludge flocs, intertwining and bridging each other to form open flocs. Filamentous bacteria are present in all flocs within the field of view, with a quantity greater than 20 bacteria per floc. Based on the filamentous bacteria identification method... Figure 1The filamentous fungi that appeared in the sample met the basic characteristics of microfilamentous fungi, and the abundance of filamentous fungi was level 5.

[0048] A sodium hypochlorite solution with an effective chlorine content of 10% was used as the reagent. The reagent was added to the sludge return after the secondary sedimentation tank, specifically at the outlet of the sludge return pump, following the procedure below:

[0049] The first phase lasts for 15 days. On the first day, the initial dose of 3g Cl / kg MLSS available chlorine (3g available chlorine per kilogram of mixed solution suspended solids) is used. The dose is added 3 times a day, with the dosing pump running for 5 hours and stopping for 3 hours.

[0050] From day 2 to day 7, a maintenance dose of 2 g Cl / kg MLSS of available chlorine was used, administered three times a day, with the dosing pump running for 5 hours and then stopping for 3 hours.

[0051] From day 8 to day 15, the effluent quality will be assessed. If the effluent quality is not significantly affected, the maintenance dose of effective chlorine will be increased to 4 g Cl / kg MLSS, and added three times a day. The dosing pump will be turned on for 3 hours and off for 5 hours.

[0052] (2) Process monitoring: Based on the addition method and frequency in step (1), process monitoring shall be performed once at the end of each 8-hour addition cycle. The specific monitoring indicators include the following:

[0053] 1) Effluent water quality: Based on the online instrument data of the total effluent, specifically including COD, TN, TP and ammonia nitrogen, all of which meet the discharge standards or the water plant's internal control standards.

[0054] Simultaneously, monitor changes in dissolved oxygen (DO) in the biological treatment tank. If an abnormal increase in DO occurs in the aeration tank, additional sampling and testing of ammonia nitrogen in the effluent from the end of the first aerobic tank and the end of the biological treatment tank should be conducted to ensure the normal operation of nitrifying bacteria. In this embodiment, the DO in the biological treatment tank remains stable.

[0055] 2) Settling performance: The 30-minute settling ratio (SV30) of the mixed liquor in the aeration tank was used. The last monitored settling ratio values ​​were 40% and 47%. Note that the mixed liquor was allowed to stand in a dark place for 30 minutes.

[0056] Simultaneously, the changes in sludge concentration (MLSS) at the east and west outlets of the biological treatment tank were monitored to control the sludge concentration balance at all outlets, thus approximating the average distribution of the chemical dosage within the biological treatment tank. Table 1 details the settling ratio (SV30) and sludge concentration (MLSS) of the mixed liquor at the outlet of the biological treatment tank after different numbers of days of chemical dosing.

[0057] 3) Microscopic examination: The mixed liquid from the effluent outlet of the biological treatment tank was taken as the observation sample. See details below. Figure 3The final monitoring results showed that the filamentous mycelia had disappeared, the sludge floc structure was stable, and the interstitial water was clear. On day 15, a final determination was made based on microscopic examination; once the mycelia around the sludge flocs disappeared, the medication was discontinued.

[0058] The analysis of Example 1 is as follows: Figure 3 These are photomicrographs (400x magnification) showing the morphological changes of sludge flocs and microfilamentous bacteria in the mixed liquor at the outlet of the biological treatment tank after 15 days of dosing. After an initial dosing of 3 g Cl / kg MLSS of available chlorine on day 1, the bridging of hyphae between flocs was significantly improved (filamentous bacteria abundance decreased to level 4). After changing to a maintenance dose of 2 g Cl / kg MLSS of available chlorine, hyphae in the flocs began to break down on day 3, and by days 5-7, the number and morphological characteristics of hyphae in the flocs showed little change (filamentous bacteria abundance level 3), reflecting an increased tolerance of microfilamentous bacteria to this dose of available chlorine. On day 8, after increasing the available chlorine dose to 4 g Cl / kg MLSS, the hyphae in the sludge flocs began to break down more rapidly for the second time. By day 13, the hyphae on the periphery of the sludge flocs had largely disappeared (filamentous bacteria abundance level 2). By day 15, the hyphae on the periphery of the sludge flocs had completely disappeared, therefore chlorination was discontinued. Figure 4 At this point, the activated sludge flocs are relatively loose, but the interstitial water is relatively clear, indicating that the activated sludge system has basically returned to normal.

[0059] Table 1 shows the 30-minute settling ratio (SV30) and sludge concentration (MLSS) of activated sludge in the mixed liquor at the effluent of the biological treatment tank after different days of chemical dosing. The trend of SV30 variation of activated sludge in the biological treatment tank is related to... Figure 3 The changes in filamentous bacteria abundance observed under a microscope showed a positive correlation; that is, as the abundance of filamentous bacteria decreased, SV30 gradually decreased until it returned to normal levels. Table 1 shows that, regarding sludge concentration, a brief difference in sludge concentration occurred between the east and west sides from day 3 to day 5. During production, the sludge concentration on both sides was restored to near uniformity by adjusting the opening of the gate in the internal return channel. Furthermore, the difference in sludge concentration before and after the addition of sodium hypochlorite was not significant, thus ruling out the influence of sludge concentration on SV30 detection.

[0060] Table 1: Settling ratio (SV30) and sludge concentration (MLSS) of the mixed liquor at the outlet of the biological treatment tank after different numbers of days of chemical dosing.

[0061]

[0062] Example 2

[0063] This embodiment provides an emergency control method for microfilamentous sludge bulking. Taking wastewater treatment plant B as an example, the specific steps are as follows:

[0064] (1) After discovering sludge bulking in the biological treatment tank of Wastewater Treatment Plant B, sodium hypochlorite solution with an effective chlorine content of 15% was used as the reagent. The reagent was added at the return sludge after the secondary sedimentation tank, specifically at the outlet of the sludge return pump, following the procedure below:

[0065] The first phase lasts for 15 days. On the first day, the initial dose of 3g Cl / kg MLSS available chlorine (3g available chlorine per kilogram of mixed solution suspended solids) is used. The dose is added 3 times a day, with the dosing pump running for 5 hours and stopping for 3 hours.

[0066] From day 2 to day 7, a maintenance dose of 2 g Cl / kg MLSS of available chlorine was used, administered three times a day, with the dosing pump running for 5 hours and then stopping for 3 hours.

[0067] From day 8 to day 15, the effluent quality is assessed. If the effluent quality is not significantly affected, the maintenance dose of available chlorine is increased to 4 g Cl / kg MLSS, administered three times a day, with the dosing pump running for 3 hours and then stopping for 5 hours. On day 9, if the effluent quality fluctuates significantly, the maintenance dose of available chlorine at 2 g Cl / kg MLSS is continued, administered three times a day, with the dosing pump running for 3 hours and then stopping for 5 hours, until day 12, when the effluent stabilizes, at which point the dose is increased to 4 g Cl / kg MLSS.

[0068] (2) Process monitoring: Based on the addition method and frequency in step (1), process monitoring shall be performed once at the end of each 8-hour addition cycle. The specific monitoring indicators include the following:

[0069] 1) Effluent water quality: Based on the online instrument data of the total effluent, specifically including COD, TN, TP and ammonia nitrogen, all of which meet the discharge standards or the water plant's internal control standards.

[0070] Simultaneously, monitor changes in dissolved oxygen (DO) in the biological treatment tank. If an abnormal increase in DO occurs in the aeration tank, additional sampling and testing of ammonia nitrogen in the effluent from the end of the first aerobic tank and the end of the biological treatment tank should be conducted to ensure the normal operation of nitrifying bacteria. In this embodiment, the DO in the biological treatment tank remains stable.

[0071] 2) Settling performance: The 30-minute settling ratio (SV30) of the mixed liquor in the aeration tank was used. The settling ratio value of the last monitoring on the 15th day was 70%. Note that the mixed liquor was left to stand in the dark for 30 minutes, and the supernatant was slightly turbid and the mud-water stratification interface was blurred.

[0072] At the same time, monitor the changes in sludge concentration (MLSS) at all outlets of the biological treatment tank and control the balance of sludge concentration at all outlets. This can be considered as an approximate average distribution of the dosage in the biological treatment tank.

[0073] 3) Microscopic examination: The mixed liquid at the outlet of the biological treatment tank was taken as the observation sample. The last monitoring result on the 15th day showed that some filamentous fungi had not yet disappeared.

[0074] (3) If the filamentous fungal hyphae are not killed according to the monitoring results of step (2), the second stage of adding the agent needs to be started. The second stage lasts for 15 days. After the 6th day, the judgment is made based on the microscopic observation. When the hyphae on the periphery of the sludge flocs are basically eliminated, the chlorination can be stopped at any time. The specific steps are as follows:

[0075] On day 1, an initial dose of 6g Cl / kg MLSS of available chlorine was used, administered three times daily, with the dosing pump running for 5 hours and then stopping for 3 hours. This was to enhance the killing effect on the mycelium of *Microphyte* by increasing the initial dose.

[0076] From day 2 to day 6, a maintenance dose of 3g Cl / kg MLSS of available chlorine was used, administered three times daily, with the dosing pump running for 5 hours and then stopping for 3 hours. The primary objective during this phase was to inhibit the growth of filamentous bacteria, while simultaneously acclimating and enhancing the tolerance of the system's functional bacteria to the disinfectant.

[0077] From day 7 to day 15, the effluent quality will be assessed. If the effluent quality is not significantly affected, the maintenance dose of available chlorine will be increased to 4 g Cl / kg MLSS, administered three times a day, with the dosing pump running for 3 hours and then stopping for 5 hours. If the effluent quality fluctuates significantly, the maintenance dose of available chlorine at 3 g Cl / kg MLSS will continue to be administered three times a day, with the dosing pump running for 3 hours and then stopping for 5 hours, until the effluent stabilizes, at which point the dose will be increased to 4 g Cl / kg MLSS.

[0078] (4) Process monitoring: Based on the addition method and frequency in step (3), process monitoring shall be performed once at the end of each 8-hour addition cycle. The specific monitoring indicators include the following:

[0079] 1) Effluent water quality: Based on the total effluent online instrument data, specifically including COD, TN, TP, and ammonia nitrogen, all of which meet the standards.

[0080] Simultaneously, monitor changes in dissolved oxygen (DO) in the biological treatment tank. If an abnormal increase in DO occurs in the aeration tank, additional sampling and testing of ammonia nitrogen in the effluent from the end of the first aerobic tank and the end of the biological treatment tank should be conducted to ensure the normal operation of nitrifying bacteria. In this embodiment, the DO in the biological treatment tank remains stable.

[0081] 2) Settling performance: The 30-minute settling ratio (SV30) of the mixed liquor in the aeration tank was 39% on the last monitoring day 15. Note that after the mixed liquor was left to stand in the dark for 30 minutes, the supernatant was clear and the mud-water stratification interface was clear.

[0082] At the same time, monitor the changes in sludge concentration (MLSS) at all outlets of the biological treatment tank and control the balance of sludge concentration at all outlets. This can be considered as an approximate average distribution of the dosage in the biological treatment tank.

[0083] 3) Microscopic examination: The mixed liquid at the effluent outlet of the biological treatment tank was taken as the observation sample. The last monitoring result on the 15th day showed that the filamentous bacteria hyphae disappeared, the sludge floc structure was stable, the interstitial water was clear, and the addition of chemicals was stopped.

[0084] Example 3

[0085] This embodiment provides an emergency control method for microfilamentous sludge bulking. Taking wastewater treatment plant C as an example, the specific steps are as follows:

[0086] (1) After sludge bulking was found in the biological treatment tank of Wastewater Treatment Plant C, sodium hypochlorite solution with an effective chlorine content of 12% was used as the reagent. The reagent was added at the return sludge after the secondary sedimentation tank, specifically at the outlet of the sludge return pump, and the reagent was added according to the following process:

[0087] The first phase lasts for 15 days. On the first day, the initial dose of 3g Cl / kg MLSS available chlorine (3g available chlorine per kilogram of mixed solution suspended solids) is used. The dose is added 3 times a day, with the dosing pump running for 5 hours and stopping for 3 hours.

[0088] From day 2 to day 7, a maintenance dose of 2 g Cl / kg MLSS of available chlorine was used, administered three times a day, with the dosing pump running for 5 hours and then stopping for 3 hours.

[0089] From day 8 to day 15, the effluent quality is assessed. If the effluent quality is not significantly affected, the maintenance dose of available chlorine is increased to 4 g Cl / kg MLSS, administered three times a day, with the dosing pump running for 3 hours and then stopping for 5 hours. On day 12, if the effluent quality fluctuates significantly, the maintenance dose of available chlorine at 2 g Cl / kg MLSS is continued, administered three times a day, with the dosing pump running for 3 hours and then stopping for 5 hours, until day 14, when the effluent stabilizes, at which point the dose is increased to 4 g Cl / kg MLSS.

[0090] (2) Process monitoring: Based on the addition method and frequency in step (1), process monitoring shall be performed once at the end of each 8-hour addition cycle. The specific monitoring indicators include the following:

[0091] 1) Effluent water quality: Based on the online instrument data of the total effluent, specifically including COD, TN, TP and ammonia nitrogen, all of which meet the discharge standards or the water plant's internal control standards.

[0092] Simultaneously, monitor changes in dissolved oxygen (DO) in the biological treatment tank. If an abnormal increase in DO occurs in the aeration tank, additional sampling and testing of ammonia nitrogen in the effluent from the end of the first aerobic tank and the end of the biological treatment tank should be conducted to ensure the normal operation of nitrifying bacteria. In this embodiment, the DO in the biological treatment tank remains stable.

[0093] 2) Settling performance: The 30-minute settling ratio (SV30) of the mixed liquor in the aeration tank was 68% on the last monitoring day 15. Note that the mixed liquor was left to stand in the dark for 30 minutes, and the supernatant was observed to be turbid and the mud-water stratification interface was blurred.

[0094] At the same time, monitor the changes in sludge concentration (MLSS) at all outlets of the biological treatment tank and control the balance of sludge concentration at all outlets. This can be considered as an approximate average distribution of the dosage in the biological treatment tank.

[0095] 3) Microscopic examination: The mixed liquid at the outlet of the biological treatment tank was taken as the observation sample. The last monitoring result on the 15th day showed that some filamentous fungi had not yet disappeared.

[0096] (3) If the monitoring results of step (2) show that the killing of filamentous fungi is not up to standard, the second stage of drug addition needs to be started. The second stage lasts for 12 days. The specific steps are as follows:

[0097] On day 1, an initial dose of 6g Cl / kg MLSS of available chlorine was used, administered three times daily, with the dosing pump running for 5 hours and then stopping for 3 hours. This was to enhance the killing effect on the mycelium of *Microphyte* by increasing the initial dose.

[0098] From day 2 to day 6, a maintenance dose of 3g Cl / kg MLSS of available chlorine was used, administered three times daily, with the dosing pump running for 5 hours and then stopping for 3 hours. The primary objective during this phase was to inhibit the growth of filamentous bacteria, while simultaneously acclimating and enhancing the tolerance of the system's functional bacteria to the disinfectant.

[0099] On days 7-12, the effluent quality was assessed. When the effluent quality was not significantly affected, the maintenance dose of effective chlorine was increased to 4 g Cl / kg MLSS, and added three times a day. The dosing pump was turned on for 3 hours and stopped for 5 hours, and the effluent quality remained stable.

[0100] (4) Process monitoring: Based on the addition method and frequency in step (3), process monitoring shall be performed once at the end of each 8-hour addition cycle. The specific monitoring indicators include the following:

[0101] 1) Effluent water quality: Based on the total effluent online instrument data, specifically including COD, TN, TP, and ammonia nitrogen, all of which meet the standards.

[0102] Simultaneously, monitor changes in dissolved oxygen (DO) in the biological treatment tank. If an abnormal increase in DO occurs in the aeration tank, additional sampling and testing of ammonia nitrogen in the effluent from the end of the first aerobic tank and the end of the biological treatment tank should be conducted to ensure the normal operation of nitrifying bacteria. In this embodiment, the DO in the biological treatment tank remains stable.

[0103] 2) Settling performance: The 30-minute settling ratio (SV30) of the mixed liquor in the aeration tank was 38% on the last monitoring day on the 12th day. Note that after the mixed liquor was left to stand in the dark for 30 minutes, the supernatant was clear and the mud-water stratification interface was clear.

[0104] At the same time, monitor the changes in sludge concentration (MLSS) at all outlets of the biological treatment tank and control the balance of sludge concentration at all outlets. This can be considered as an approximate average distribution of the dosage in the biological treatment tank.

[0105] 3) Microscopic examination: The mixed liquid at the effluent outlet of the biological treatment tank was taken as the observation sample. The last monitoring result on the 12th day showed that the filamentous bacteria hyphae disappeared. At the same time, the sludge floc structure was stable and the interstitial water was clear. The addition of chemicals was stopped.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An emergency control method for microfilamentous sludge bulking, characterized in that, Includes the following steps: S1. Chemical dosing: Add chemicals to the return sludge according to the first set procedure; S2. Process monitoring: Monitoring shall be carried out once at the end of each dosing cycle. The monitoring indicators include total effluent quality, sedimentation performance of mixed liquor in biological treatment tank, and microscopic examination of mixed liquor at the outlet of biological treatment tank. S3. If the last monitoring indicator in S2 is qualified, the drug addition is ended. If the last monitoring indicator in S2 fails to meet the requirements, the second stage of reagent addition will be initiated: reagents will be added to the return sludge according to the second set procedure. In S1, the first set process lasts for a total of 15 days. The specific process is as follows: On day 1, the reagent is used at a dose of 3g Cl / kg MLSS available chlorine; from day 2 to day 7, the reagent is used at a maintenance dose of 2g Cl / kg MLSS available chlorine. On days 8-15, the overall effluent quality will be assessed. If the overall effluent quality remains stable, the maintenance dose of available chlorine will be increased to 4 g Cl / kg MLSS. If the overall effluent water quality fluctuates, continue to add 2g Cl / kg MLSS of available chlorine until the overall effluent water quality stabilizes, and then increase the maintenance dose of available chlorine to 4g Cl / kg MLSS. In S3, if the second stage of reagent addition is initiated, the second round of process monitoring will be carried out simultaneously with reference to S2. The specific process of the second set procedure is as follows: On the first day, the reagent dosage is 6g Cl / kg MLSS available chlorine. From day 2 to day 6, the medication was maintained at a dose of 3 g Cl / kg MLSS of available chlorine. If the monitoring indicators are qualified after the 6th day, the dosing of the agent will be stopped; in the second set process, if the monitoring indicators are not qualified after the 6th day, the dosing of the agent will continue. The specific process is as follows: from the 7th to the 15th day, the overall effluent water quality will be judged. If the overall effluent water quality remains stable, the maintenance dose of effective chlorine will be increased to 4g Cl / kg MLSS. If the overall effluent water quality fluctuates, continue to add an effective chlorine maintenance dose of 3gCl / kg MLSS until the overall effluent water quality stabilizes, and then increase the effective chlorine maintenance dose to 4gCl / kg MLSS. In the second set process, if the process monitoring indicators are qualified during days 7-15, the drug addition will be terminated.

2. The emergency control method for microfilamentous sludge bulking as described in claim 1, characterized in that, The agent is a chlorine-containing disinfectant with an effective chlorine content of 10-15%.

3. The emergency control method for microfilamentous sludge bulking as described in claim 1, characterized in that, The location for adding chemicals to the returned sludge is either the outlet of the sludge return pump or the sludge return channel.

4. The emergency control method for microfilamentous sludge bulking as described in claim 2, characterized in that, The dosage is divided into 3 dosing cycles per day. During each dosing cycle, the dosage is added for 3-5 hours and then stopped for 3-5 hours.

5. The emergency control method for microfilamentous sludge bulking as described in claim 1, characterized in that, The agent is a mixture of disinfectant and coagulant.

6. The emergency control method for microfilamentous sludge bulking as described in claim 1, characterized in that, In S2, the total effluent water quality monitoring includes COD, TN, TP, and ammonia nitrogen; The settling performance of the mixed liquor in the biological treatment tank is the same as the settling ratio of the mixed liquor in the aeration tank after 30 minutes. Microscopic examination of the mixed liquor at the effluent outlet of the biological treatment tank includes changes in mycelium, the state of sludge flocs, and the transparency of interstitial water.

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