CN112607854A

CN112607854A - Method for rapidly regulating and controlling malignant swelling of activated sludge in SBR (sequencing batch reactor)

Info

Publication number: CN112607854A
Application number: CN202011402995.6A
Authority: CN
Inventors: 高春娣; 王传德; 侯春艳; 李悦
Original assignee: Beijing University of Technology
Current assignee: Beijing University of Technology
Priority date: 2020-12-02
Filing date: 2020-12-02
Publication date: 2021-04-06

Abstract

A method for rapidly regulating and controlling the malignant swelling of activated sludge in an SBR reactor belongs to the technical field of biological sewage treatment. The method comprises the steps of inoculating return sludge of a sewage treatment plant into an SBR reactor, domesticating for 10 days in a first stage, and running a test in a single-period aerobic-deficient alternative mode for 6 times (the ratio of aerobic-deficient time in each time is 2:1) and a low dissolved oxygen mode (0.8-1.2 mg/L) in a second stage, wherein malignant expansion (SVI is more than 500ml/g) occurs when the test is run for 40 days. The third stage regulates the malignant expansion of the sludge by coupling the characteristics of sludge expansion control and non-specific methods: firstly, the ratio of the anaerobic time to the aerobic time in each alternation is changed to 1:2, aeration is increased to improve the dissolved oxygen concentration to be more than 2.0mg/L, and then ferric trichloride flocculant is added at the end of the reaction stage of each period to shorten the sludge age. After 13 days of operation, the SVI value is reduced to below 150mg/L and finally maintained at 90-110 mg/L, and the rapid control of the sludge malignant expansion in the SBR reactor is realized.

Description

Method for rapidly regulating and controlling malignant swelling of activated sludge in SBR (sequencing batch reactor)

Technical Field

The invention belongs to the field of sewage treatment, and provides a method for quickly regulating and controlling malignant swelling of activated sludge in an SBR (sequencing batch reactor).

Background

Since the activated sludge process has been widely used in various sewage treatment plants, the problem of sludge bulking has been one of the difficulties that plague sewage treatment workers. Sludge bulking is extremely hazardous and recovery time is long, so the method is called as activated sludge method 'cancer', and the prevention and control of sludge bulking is one of the main directions of current research.

The sludge bulking refers to a state that the sedimentation speed of the activated sludge is slow and the compression of activated sludge flocs is deteriorated. Once the sludge is expanded, the normal operation of the process is damaged, the sludge settleability is deteriorated, the normal sludge-water separation in the secondary sedimentation tank is influenced, and the sludge is lost along with the effluent, so that the effluent quality is deteriorated. Meanwhile, the concentration of the return sludge is reduced, which can reduce the biomass needed in the aeration tank and further influence the treatment effect. In addition, the expanded sludge also increases the burden and expense of subsequent sludge treatment, sludge disposal. Therefore, prevention and control of sludge bulking is of paramount importance in the daily management of process operations.

The current methods for controlling sludge bulking roughly include two major types, specific methods and non-specific methods. The specific method comprises a biological selector, methods for improving dissolved oxygen and changing organic load and temperature, and the like, is a common regulation and control method at present, and is proposed aiming at sludge bulking caused under different conditions, and has strong specificity but long recovery time. The non-specific method mainly refers to a method for controlling sludge bulking by adding an oxidant or a flocculating agent, the growth of filamentous bacteria can be generally inhibited by adding a disinfectant, but the zoogloea bacteria can be killed when the adding amount is excessive, and the phenomenon of 'rebounding' can occur when the adding amount is stopped.

Aiming at the problems of great sludge bulking damage, long recovery time and the like, it is necessary to develop a method for quickly and effectively regulating and controlling sludge bulking. By coupling the specific method for changing corresponding operation parameters with the non-specific method for adding chemical agents, the rapid control of the malignant expansion of the sludge can be realized, the problem of sludge loss caused by poor sludge settleability is effectively prevented, and the flora structure and activity of the expanded sludge are recovered to a normal state in a short time, so that the normal operation of the treatment process is ensured.

Disclosure of Invention

Aiming at the problem of long control period of sludge bulking at present, the invention provides a method for quickly regulating and controlling malignant bulking of sludge in an SBR reactor, which belongs to the field of biological sewage treatment, can recover the flora structure and activity of the sludge in a short time, effectively prevents sludge loss and enables the treatment process to be recovered to be normal. Provides a new idea and method for the operation regulation and control of the actual sewage plant. The method is simple to operate, is quick and effective, and can quickly recover the bioreactor to be stable in a malignant swelling state.

A method for rapidly regulating and controlling malignant swelling of activated sludge in an SBR reactor is characterized in that influent water is selected as domestic sewage of a residential area, the domestic sewage belongs to typical domestic sewage with low C/N ratio, the organic load of the sludge is low, and the specific influent water quality is as follows: COD concentration is 86.3-240.5 mg/L, NH₄ ⁺-N concentration of 45.3-82 mg/L, pH of 6.8-7.6, C/N ratio of 2.5-3.5. The specific operation steps are as follows:

(1) inoculating return sludge taken from a sewage treatment plant into an SBR reactor, acclimating in an aerobic way in the whole process, and controlling the dissolved oxygen concentration to be more than 2.0 mg/L. One operation period is 6h, 4 periods are taken one day, and acclimatization is carried out for 10 days.

(2) Initiation of sludge malignant swelling: after the stage (1), changing the operation conditions, operating the reactor in an SBR reactor in an alternate aeration mode, feeding water for 5min every period, then alternately operating for 6 times in an anoxic 30min and aerobic 15min mode, continuously stirring during the reaction period, statically settling after the reaction is finished, wherein the statically settling time is 80min, the water discharging time is 5min, the dissolved oxygen of an aerobic section is controlled to be 0.8-1.2 mg/L, and the sludge age is maintained at 30 d. One operation period T is 6h, 4 periods per day, the operation is continuously carried out for 30-50 days under the condition, and the volume fraction of the precipitated sludge, namely SV, is obtained after the mixed liquor in the aeration tank is statically precipitated for 30min₃₀If the concentration exceeds 95%, the next stage is carried out.

(3) Fast control of sludge malignant swelling: the control method mainly comprises four aspects:

firstly, increasing aeration time, changing the ratio of anoxic and aerobic time to 1:2, alternately operating 6 times in a mode of oxygen deficiency for 15min and oxygen deficiency for 30min in each period.

And secondly, increasing aeration rate, adjusting a rotor flow meter to increase aeration rate, and increasing the dissolved oxygen of an aerobic section in the SBR reaction process to be more than 2.0 mg/L.

And thirdly, adding a ferric trichloride flocculating agent, and adding the ferric trichloride flocculating agent at the end of the reaction stage of each period, wherein the concentration of the flocculating agent in the reactor reaches 120 mg/L.

Fourthly, the sludge discharge amount is increased every day, and the sludge age is maintained at 15-18 days.

And (3) feeding water for 5min every period, wherein the reaction time is 270min, the stirrer is continuously stirred during the reaction, the precipitation time is 80min, and the water drainage time is 5 min. One operation period is 6 hours, 4 periods are operated every day, and the operation lasts for 10-30 days.

After the step (2), the SVI value is measured every day, and when the reaction is carried out to the 40 th day, the sludge is seriously swelled (SVI is more than 500ml/g), the settleability is extremely poor, the sludge is seriously lost along with the effluent, and the sludge concentration is reduced to below 2000 mg/L. Gram staining, nano staining and FISH experiments are carried out on the sludge subjected to malignant bulking, and the fact that the dominant filamentous bacterium in the malignant bulking is Type 0092 filamentous bacterium is proved to be one of the common dominant filamentous bacteria in municipal domestic sewage treatment plants.

After the step (3), the SVI value of the malignant expanded sludge is rapidly reduced, after the regulation and control for 13 days, the SVI value is reduced to be below 150mg/L, and after the operation for 7 days, the SVI value is finally stabilized at 90-110 mg/L.

Preferably, the activated sludge concentration after the step (1) is inoculated to the SBR reactor is as follows: 2000-3500 mg/L.

Preferably, the temperature in the whole operation process is maintained at 26-28 ℃ (preferably 27 ℃), the dissolved oxygen of the aerobic section in the step (2) is controlled at 0.8-1.2 mg/L (preferably 1.0mg/L), and the dissolved oxygen of the aerobic section in the step (3) is increased to more than 2.0 mg/L.

Preferably, the ratio of the anoxic and aerobic time of each alternation in the step (2) is 2:1, the ratio of the anoxic and aerobic time of each alternation in the step (3) is 1: 2.

Preferably, after the ferric trichloride flocculating agent is added in the step (3), the concentration of the flocculating agent in the reactor is 120 mg/L.

Preferably, the sludge age in step (3) is maintained for 15 to 18 days.

Preferably, the step (2) is carried out for 40 days; and (3) operating for 20 days.

The drainage ratio per cycle of the SBR reactor was 50%.

Compared with the prior art, the invention has the following advantages:

the method for quickly regulating and controlling the malignant expansion of the activated sludge in the SBR reactor is suitable for the problem of the malignant expansion of the sludge caused by low dissolved oxygen and intermittent aeration in the conventional urban sewage plant. The method is simple to operate, has obvious regulation and control effect, can control the problem of malignant expansion of the sludge in a short time, can effectively prevent the sludge from losing, and provides a quick and effective regulation and control method for sludge expansion for various actual sewage treatment plants.

Drawings

FIG. 1 is a schematic view of the structure of the SBR reactor in the present invention:

1. a water inlet barrel; 2. a peristaltic pump; 3. a water inlet valve; 4. a water outlet valve; 5. discharging the water barrel; 6. a stirrer; 7. an aeration disc; 8. an air compressor; 9. a rotameter; 10. a water quality dissolved oxygen instrument; 11. a pH probe; 12. a DO probe; 13. a temperature controller;

FIG. 2 shows the change of SVI values at different stages of the whole reaction process;

FIGS. 3a and 3b are the gram and the nano-stain respectively in the state of malignant swelling of the sludge after the completion of step (2);

FIG. 4 is a FISH dominant filamentous bacterium detection diagram in a sludge malignant swelling state after the completion of step (2);

FIGS. 5a and 5b are gram and nano-stain diagrams of sludge in a sludge recovery state after step (3) is completed;

Detailed Description

The invention is further described in detail below with reference to the accompanying drawings and specific control methods:

the invention adopts the SBR reactor, the inoculated sludge is the return sludge of a sewage treatment plant in a high tombstone shop, and the sedimentation performance of the sludge is good. The sludge taken was acclimated for 10 days to restore activity: the concentration of the inoculated sludge is maintained at 2000-3500 mg/L. In the operation process, firstly opening a water inlet valve for one-time water inlet in a short-time water inlet mode, wherein the water inlet time is 5min, opening a temperature control device to set the temperature to be 27 ℃, adjusting a rotor flow meter to control the aeration amount of an aerobic section, and controlling the concentration of dissolved oxygen to be more than 2.0 mg/L; and (3) turning on the stirrer to fully mix the mud-water mixture, wherein the aeration time is 5h, stopping stirring after the aeration is finished, entering a precipitation period, wherein the precipitation time is 50min, turning on a drain valve after the precipitation period is finished, draining for 5min, and draining the supernatant with the drainage ratio of 50%. And (5) re-feeding water into the next period, repeatedly running for 10 days in this way, and entering the next stage.

The actual domestic sewage with low C/N ratio is adopted in the test period, and the specific water quality ranges are as follows: COD concentration is 86.3-240.5 mg/L, NH₄ ⁺-N concentration of 45.3-82 mg/L, pH of 6.8-7.6, C/N ratio of 2.5-3.5.

After the domestication stage, changing the operation parameters, and entering a second stage: and in the initiation stage of the sludge malignant expansion, the operation is carried out in an anoxic-aerobic alternative mode, water is fed for 5min per period, then the operation is carried out for 6 times in an anoxic 30min and aerobic 15min mode, then the precipitation is carried out for 80min, the water is discharged for 5min, the aeration rate is reduced by adjusting a rotameter, and the dissolved oxygen in an aerobic section is controlled to be 0.8-1.2 mg/L. The sludge age is controlled to be 30 days, other conditions are kept unchanged, 4 periods are carried out every day, and the operation lasts for 30-50 days. When the sludge was run to day 40, the sludge was maliciously Swelled (SV)₃₀>95％，SVI>500mL/g), the microscopic examination can clearly see that a large number of filamentous bacteria exist in the activated sludge, and gram and nano-type staining is carried out on the sludge, wherein figure 3a shows that hyphae are gram-stained and are red, namely negative, and figure 3b shows that nano-type staining is blue-gray, namely positive. The dominant filamentous bacterium is further qualitatively analyzed by using a FISH method, and the dominant filamentous bacterium is a Type 0092 filamentous bacterium (see figure 4).

The method for regulating and controlling the malignant swelling sludge comprises the following four aspects: firstly, increasing aeration time, and changing the ratio of the anoxic time to the aerobic time in each alternation to 1:2 under the condition of not changing alternation times, namely, alternately operating in an anoxic mode for 15min and an aerobic mode for 30min in each period; secondly, increasing aeration quantity, and controlling the dissolved oxygen of the aerobic section to be more than 2.0mg/L by adjusting a rotor flow meter; thirdly, adding a flocculating agent, and adding a ferric trichloride solution into the reaction period at the end of the reaction period of each period to ensure that the concentration of the ferric trichloride flocculating agent in the reactor is 120 mg/L; fourthly, the sludge discharge amount per day is increased, and the sludge age is maintained at 15-18 days. Keeping the temperature unchanged, wherein one operation period is 6 hours, and the operation is carried out for 4 periods every day for 10-30 days.

The change of the sedimentation performance of the sludge is judged by measuring the SVI value every day in the test process, and the change trend of the SVI value in the whole process is shown in figure 2.

Through the measurement of SVI every day, the SVI value is reduced to below 150mg/L after the regulation and control for 13 days, and is stabilized at 90-110 mg/L after the operation for 7 days. By performing gram and nano-type staining on the sludge, the gram staining result is shown in figure 5a, and the nano-type staining result is shown in figure 5b, the sludge is found to have a good floc structure, the number of filamentous bacteria is small, and the malignant swelling of the sludge is recovered.

After 20 days of operation, the sludge is recovered to normal sedimentation performance (SVI is maintained at 90-110 mL/g) and floc structure from a malignant swelling (SVI >500mL/g) state. The method couples the specific and nonspecific methods of sludge bulking control, has obvious regulating and controlling effect and shorter control time, thereby providing an effective rapid regulating and controlling method of the malignant bulking of the sludge.

The foregoing is a detailed description of the invention that will enable one skilled in the art to better understand and utilize the invention, and the practice of the invention is not limited thereto, and thus, simple modifications of the invention by one skilled in the art are intended to be within the scope of the invention.

Claims

1. A method for quickly regulating and controlling the malignant swelling of activated sludge in an SBR reactor,the method is characterized in that the inlet water quality is as follows: the COD concentration range is 86.3-240.5 MG/L, NH₄ ⁺-N concentration of 45.3-82 MG/L, pH range of 6.8-7.6, C/N range of 2.5-3.5; the sludge concentration is maintained at 2000-3500 MG/L in the whole operation process, the temperature is maintained at 26-28 ℃ by using a heating rod, and the water drainage ratio of the SBR reactor is 50%; the specific process comprises the following three stages:

(1) a sludge domestication stage, wherein activated sludge taken from a sewage treatment plant is inoculated into an SBR reactor, domestication is carried out in a full-process aerobic manner, the dissolved oxygen concentration is controlled to be more than 2.0mg/L, and the next stage is carried out after domestication is carried out for 10 days;

(2) the initiation stage of the sludge malignant swelling comprises the following steps:

the method comprises the following steps that water is fed into an SBR reactor once by using a peristaltic pump at the beginning of each period, the water feeding time is 5min, the SBR reactor is operated in an anoxic-aerobic alternative mode after water feeding, the SBR reactor is operated in an anoxic-aerobic alternative mode for 6 times in an anoxic-30 min and aerobic-15 min mode in each period, the total reaction time is 270min, then precipitation is carried out for 80min, water is discharged for 5min, stirring is carried out continuously during the reaction, the aeration amount is controlled during the reaction, the dissolved oxygen in an aerobic section is kept at 0.8-1.2 mg/L, and the sludge age is maintained for 30 days by regularly discharging sludge every day; one operation period is 6 hours, the operation is carried out for 4 periods every day, the operation is carried out for 30-50 days totally, and when the mixed liquid in the aeration tank is statically precipitated for 30min, the volume fraction of the precipitated sludge is SV₃₀If the content exceeds 95 percent, the next stage can be started;

(3) the rapid control stage of the sludge malignant expansion comprises the following steps:

the SBR reactor is continuously operated in a mode of lacking the oxygen and alternating for 6 times per period on the sludge after the stage (2), and the rapid control on the malignant expansion of the sludge in each reaction period comprises the following four aspects: firstly, increasing aeration time, controlling the aerobic deficiency time under the condition of not changing alternation times, and alternately operating in an anoxic mode for 15min and an aerobic mode for 30min in each period; secondly, increasing aeration quantity, and controlling the dissolved oxygen of the aerobic section to be more than 2.0mg/L by adjusting a rotor flow meter; thirdly, adding a flocculating agent, adding ferric trichloride solution into the reaction period at the end of the reaction period of each period, wherein the concentration of the ferric trichloride flocculating agent in the reactor after the addition is 120 mg/L; fourthly, increasing the sludge discharge amount every day, and maintaining the sludge age at 15-18 days; and one operation period is 6 hours, the operation is carried out for 4 periods every day, the operation is carried out for 10-30 days totally, and the operation is finished when the volume value (namely the SVI value) occupied by the corresponding 1g of dry sludge is stabilized below 150mL/g after the mixed liquor in the aeration tank is precipitated for 30 min.