Method and system for early warning and controlling sludge bulking of sewage treatment system in coal chemical industry

Abstract

The invention relates to a coal chemical sewage treatment system sludge bulking early warning and control method, which comprises the following steps: mixing qualified water and unqualified water, and carrying out biochemical treatment; monitoring the physical state index of the precipitated sludge and the effluent quality; analyzing and monitoring the physical state index of the precipitated sludge and the effluent quality to evaluate the sludge bulking degree, and determining that the early warning levels are divided into high danger, relatively high danger, medium danger and general danger from high to low; wherein when the danger is high, the detection frequency is adjusted, the reflux quantity is adjusted to 200%, and 100 ppm of activated carbon is added; when the danger level is high, the detection frequency is adjusted, and backflow is adjusted to 150%; the detection frequency is adjusted in the middle danger level, backflow is adjusted to 100%, and the monitoring frequency is adjusted in the general danger level, so that the working condition returns to normal. The method is suitable for common mixed expansion of filamentous bacterium expansion and viscous expansion coexisting in coal chemical sewage. According to the sludge bulking early warning measure, control is started from sewage inflow, various indexes of sewage inflow are monitored in real time, and water quality abnormity is found in time, early warned in time and regulated in time.

Description

Technical Field

[0001] The invention belongs to the field of sewage treatment and sludge conditioning, and in particular relates to a method and system for early warning and controlling sludge bulking in a coal chemical sewage treatment system. Background Art

[0002] The coal chemical industry is diverse, with great differences in the applied technical means and product quality. The quality of industrial wastewater changes with the operation of the main production process. It mainly includes substances such as ammonia nitrogen, phenols, aldehydes, petroleum and suspended solids (SS). It contains a large number of toxic and difficult-to-degrade compounds, including heavy metal ions or compounds such as copper and iron, as well as sulfides, cyanides, etc. Therefore, the coal chemical production wastewater has the characteristics of complex composition, high concentration of organic matter, large fluctuations in water quality and high difficulty in treatment.

[0003] The sewage treatment section is a back-end auxiliary process in the coal chemical industry, and the sewage effluent indicators have strict environmental protection indicators. At present, the coal chemical sewage treatment is mainly based on biological treatment, but due to fluctuations in the coal chemical process or changes in the quality of raw coal, the wastewater components and content will fluctuate, which is easy to cause sludge swelling in the biological system. In a system with a "zero discharge" process for wastewater, the sewage treatment section plays a vital role in the main process and "zero discharge". Once sludge swelling occurs, if effective measures are not taken in time to control it, the sludge will enter the next section with the water, and the effluent water quality will deteriorate, resulting in a series of serious problems such as low efficiency of deep treatment of sewage treatment, biological fouling in the membrane system, low quality of salt produced in the "evaporation" section, and decreased water production of desalted water, which ultimately affects the normal operation of the main process of coal chemical industry and is not conducive to the safe and stable operation of the entire system.

[0004] Therefore, designing and developing an early warning and control system for sludge bulking suitable for the characteristics of coal chemical wastewater treatment systems is an urgent problem to be solved in the wastewater treatment part of the "large chemical production" of coal chemical industry. Summary of the invention

[0005] The invention discloses a method and system for early warning and controlling sludge bulking in a coal chemical wastewater treatment system, and proposes an emergency response and control technology.

[0006] A sludge bulking early warning and control method for a coal chemical wastewater treatment system, specifically comprising the following steps: (1) Sewage inflow control: Mix qualified water and unqualified water and enter biochemical treatment; (2) Sludge physical state monitoring: monitoring the physical state indicators of sedimentation sludge and effluent water quality; (3) Sludge bulking warning and emergency control: Analyze and monitor the physical state indicators of the settled sludge and the effluent water quality to evaluate the degree of sludge bulking, and determine the warning level from high to low, divided into high risk, relatively high risk, medium risk and general risk; in the case of high risk, adjust the monitoring frequency, adjust the reflux rate to 200%, and add 100ppm of activated carbon; in the case of relatively high risk, adjust the monitoring frequency, adjust the reflux rate to 150%; in the case of medium risk, adjust the monitoring frequency, adjust the reflux rate to 100%, and in the case of general risk, adjust the monitoring frequency to restore the working conditions to normal; The reflux includes dosing reflux and / or sludge reflux, and the ratio is 1:5; the dosing reflux is mixed sludge obtained by mixing inorganic sludge with sedimentation sludge, and the inorganic sludge is flocs composed of insoluble matter such as calcium carbonate, magnesium hydroxide, aluminosilicate, and a small amount of flocculants and coagulants, and the surface charge of the flocs is positive; In the case of medium risk level, the reflux is only sludge reflux; in the case of high risk or relatively high risk level, the reflux is drug reflux and sludge reflux.

[0007] Preferably, the amount of inorganic sludge added to the dosing reflux at the high risk and relatively high risk levels is 300ppm and 200ppm of the mixed sludge amount, respectively.

[0008] Preferably, the monitoring frequency is adjusted in high risk, relatively high risk and medium risk situations according to the sludge microscopic examination image, and the monitoring frequencies are once every 12 hours, once every 24 hours and once every 24 hours respectively; the monitoring frequency is adjusted in general risk according to the sludge settling index SV30, and the monitoring frequency is 12 hours.

[0009] Preferably, the sludge physical state indicators include sludge settling index SV30, sludge volume index SVI and sludge microscopic examination image; the sludge microscopic examination image includes the growth of filamentous bacteria in sludge, the morphology of bacterial flocs and the clarity of interstitial water.

[0010] Preferably, the warning level evaluation criteria are as follows: High risk: abnormal water discharge index, SVI ≥ 250 ml / g, SV30 ≥ 90%; The higher risk: the water discharge index is normal, and SVI ≥ 250 ml / g, SV30 ≥ 90%; Moderate danger: water discharge index is normal, and 150 ml / g≤SVI≤250 ml / g, SV30≥80%; General danger: water output indicators are normal, with SVI ≤ 150 ml / g and SV30 ≥ 80%.

[0011] Preferably, the qualified water and unqualified water are judged as follows: S1: For incoming water, the online monitoring system analyzes water quality indicators every hour. If any of the indicators exceeds 20% and deviates from the design value by 20%, it is judged as unqualified incoming water; S2: When the incoming water is judged as unqualified, the water inlet valve of the regulating pool is immediately closed, and the water inlet valve of the unqualified pool is opened to temporarily store the unqualified incoming water; S3: Start the emergency mode and analyze the water quality index every 20 minutes until the index is qualified three times in a row, then return to the normal mode and judge the water as qualified; S4: Immediately close the water inlet valve of the unqualified water pool, open the water inlet valve of the regulating pool, and the sewage enters the regulating pool normally. The online monitoring system switches to normal mode and the analysis frequency is restored to once an hour.

[0012] Preferably, the unqualified water and qualified water are mixed in a ratio of 1:10 to 3:10.

[0013] A sludge bulking early warning and control system for a coal chemical wastewater treatment system, the system comprising a regulating tank, an unqualified water tank, an AOAO tank, a secondary sedimentation tank, and an accident tank, the regulating tank and the unqualified water tank are connected in parallel and are connected in sequence to the AOAO tank, the secondary sedimentation tank, and the accident tank; The accident pool outlet is connected to the regulating pool inlet; The sludge outlet pipeline of the secondary sedimentation tank is connected to the AOAO tank return pipeline; The sludge outlet pipeline of the secondary sedimentation tank is connected to the sludge conditioning tank, and the inlet of the sludge conditioning tank is connected to the inorganic sludge storage tank; An activated carbon storage tank is also provided between the AOAO tank and the secondary sedimentation tank; The AOAO tank end and the secondary sedimentation tank are both provided with sludge state collection devices, and the regulating tank inlet and the secondary sedimentation tank outlet pipelines are both provided with water quality analysis devices.

[0014] Preferably, the regulating tank and the unqualified water tank inlet are both provided with water inlet valves.

[0015] Advantages of the present invention (1) The present invention proposes a method for early warning and control of sludge bulking in a coal chemical wastewater treatment system, which is suitable for mixed bulking in which filamentous bacterial bulking and viscous bulking, which are common in coal chemical wastewater, coexist. The important reason for the occurrence of sludge bulking is the fluctuation of influent water quality and load, which has a great impact on the microbial system. The sludge bulking early warning measures proposed in the present invention propose to start control from the inlet of sewage, monitor various indicators of the inlet of sewage in real time, and promptly discover, warn and regulate abnormal water quality. The sewage treatment system of the present invention is provided with a regulating tank to homogenize the water quality and reduce the impact of water quality fluctuations on the biochemical system; an unqualified water tank is provided to temporarily store unqualified incoming water to prevent unqualified water from directly entering the biochemical system, which will have an adverse effect on microorganisms and cause the effluent water quality to be substandard; the accident tank temporarily stores unqualified effluent from the secondary sedimentation tank, strictly controls the effluent indicators and avoids adverse effects on subsequent processes; (2) The sludge bulking early warning system of the present invention combines sludge state and water quality analysis, comprehensively analyzes the physical state of sludge and changes in effluent water quality, evaluates the impact of sludge bulking on sewage treatment, comprehensively judges the potential risk level from multiple angles, and gives more effective control instructions. The sludge bulking control system of the present invention is equipped with a sludge conditioning tank, which proposes a new idea of ​​conditioning part of the sludge to avoid greater damage to the biological system caused by improper operation; (3) The inorganic sludge of the present invention is mainly composed of insoluble substances such as calcium carbonate, magnesium hydroxide, aluminosilicate, and a small amount of flocculants and coagulants, and the surface charge of the flocs is positive. When the inorganic sludge is added to the sludge conditioning tank, it can be used as an adsorption center to adsorb the bacterial flocs with negative surface charge. The flocs have a large mass and can accelerate the sludge sedimentation. At the same time, combined with the addition of activated carbon, it can effectively deal with the situation where the effluent index is unqualified due to severe sludge swelling. The emergency control effect is good and the response speed is fast, ensuring the water production of the sewage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The schematic diagram is a structural diagram of a sludge bulking early warning and control system for a coal chemical wastewater treatment system.

[0017] Figure 2 The present invention is a flow chart of a sewage inlet control method of a sludge bulking early warning and control system of a sewage treatment system.

[0018] Figure 3 The present invention is a sludge bulking warning and emergency control flow chart of a sludge bulking warning and control system for a sewage treatment system.

[0019] Reference numerals: 1-regulating tank, 2-unqualified water tank, 3-AOAO tank, 4-secondary sedimentation tank, 5-accident tank, 7-sludge conditioning tank, 8-inorganic sludge storage tank, 9-activated carbon storage tank, 11-water quality analysis device, 12-water quality analysis device, 21-sludge physical state collection device, 22-sludge physical state collection device. DETAILED DESCRIPTION

[0020] The regulating tank 1 is used to homogenize the incoming water and buffer the water volume; the unqualified water tank 2 is used to temporarily store the incoming water that does not meet the sewage inlet index; the accident tank 5 is used to store the effluent from the secondary sedimentation tank that does not meet the effluent index.

[0021] The sludge physical state collection device 21 of the AOAO tank 3, the sludge physical state collection device 22 of the secondary sedimentation tank 4, the water quality analysis device at the outlet of the secondary sedimentation tank 4 and the water quality analysis component at the inlet of the regulating tank together constitute a sludge bulking early warning system; The activated carbon storage tank 9, the sludge return and the drug return constitute a sludge bulking control system, and all devices of the sludge bulking control system are controlled online by an intelligent control system; The sludge return is the precipitated sludge that is connected to the return line of the AOAO tank 3 from the outlet of the secondary sedimentation tank 4; The dosing reflux is the mixed sludge after the sedimentation sludge and the inorganic sludge are mixed in the sludge conditioning tank 7; the sedimentation sludge is directly the sludge in the secondary sedimentation tank 4, and the inorganic sludge is the sludge in the inorganic sludge storage tank 8; "Zero discharge" inorganic sludge comes from zero discharge high-density sedimentation tank. Zero discharge water has high hardness and silicon, and agents such as polyferric sulfate (PFS), polyacrylamide (PAM), sodium hydroxide solution, calcium carbonate and sodium aluminate are added to remove most of the suspended matter and hardness in the water, as well as some organic matter, and reduce the turbidity of the effluent. In addition, the agents added to the "zero discharge" high-density sludge conditioning tank are mainly common agents such as inorganic alkali, inorganic salts, coagulants and flocculants, which have little effect on the sewage biological system. Therefore, the use of "zero discharge" sludge in the sludge bulking control link does not introduce foreign pathogens, nor does it seriously threaten the microbial system of the biochemical system, and the safety risk is low. "Zero discharge" inorganic sludge is mainly composed of flocs composed of insoluble substances such as calcium carbonate, magnesium hydroxide, silicate, and a small amount of flocculants and coagulants, and the surface charge of the flocs is positive, which can serve as an adsorption center to promote the attachment of bacterial flocs with negative surface charge, and the flocs are large in mass, which is conducive to sludge sedimentation. Example

[0022] A sludge bulking early warning and control system for a coal chemical wastewater treatment system, the system comprising a regulating tank 1, an unqualified water tank 2, an AOAO tank 3, a secondary sedimentation tank 4, and an accident tank 5, wherein the regulating tank 1 and the unqualified water tank 3 are connected in parallel and are connected in sequence to the AOAO tank 3, the secondary sedimentation tank 4, and the accident tank 5; The outlet of the accident pool 5 is connected to the inlet of the regulating pool 1; The sludge outlet pipeline of the secondary sedimentation tank 4 is connected to the return pipeline of the AOAO tank 3; The sludge outlet pipeline of the secondary sedimentation tank 4 is connected to the sludge conditioning tank 7, and the inlet of the sludge conditioning tank 7 is connected to the inorganic sludge storage tank 8; An activated carbon storage tank 9 is also provided between the AOAO tank 3 and the secondary sedimentation tank 4; The AOAO tank 3 end and the secondary sedimentation tank 4 are both provided with sludge state collection devices, and the regulating tank 1 inlet and the secondary sedimentation tank 4 outlet pipelines are both provided with water quality analysis devices; The inlets of the regulating tank 1 and the unqualified water tank 2 are both provided with water inlet valves.

[0023] When all indicators of the coal chemical polluted water treatment system are normal, the sewage water can be treated in the regulating tank 1, AOAO tank 3 and secondary sedimentation tank 4 in sequence.

[0024] When the indicators are abnormal, the sludge bulking early warning and control method of the coal chemical wastewater treatment system is implemented as follows: (1) Sewage inflow control: Mix qualified water and unqualified water; specifically: S1: The water quality index is analyzed once an hour through the online monitoring system of the water quality analysis device at the inlet of regulating tank 1. If there are more than 20% of the indexes and deviate from the design value by 20%, it is judged as unqualified water; S2: When the incoming water is judged as unqualified, the water inlet valve of regulating tank 1 is immediately closed, and the water inlet valve of unqualified tank 2 is opened to temporarily store the unqualified incoming water; S3: Start the emergency mode and analyze the water quality index every 20 minutes until the index is qualified three times in a row, then return to the normal mode and judge the water as qualified; S4: Immediately close the inlet valve of unqualified pool 2, open the inlet valve of regulating pool 1, and the sewage enters regulating pool 1 normally. The online monitoring system switches to normal mode, and the analysis frequency is restored to once an hour. The unqualified water is mixed with the qualified water at a ratio of 1:10 to 3:10, and then enters AOAO pool 3 for biochemical treatment; (2) Monitoring of sludge physical state: The monitoring frequency of sludge physical state is once a day. The sampling locations are fixed to the sludge physical state collection device 21 of the AOAO tank 3 and the sludge physical state collection device 22 of the secondary sedimentation tank 4. The samples are collected manually and then transmitted for analysis. The collection indicators of the sludge physical state monitor the three indicators of sludge settling index SV30, sludge volume index SVI and sludge microscopic examination image; the microbial microscopic examination image mainly analyzes and monitors the three indicators of sludge filamentous bacteria growth, bacterial floc morphology and interstitial water clarity; (3) Sludge bulking warning and emergency control: Analyze the monitoring indicators of the physical state of sludge bulking and the monitoring system of the water quality analysis device 12 at the outlet of the secondary sedimentation tank 4, comprehensively evaluate the degree of sludge bulking, and issue a warning level signal to the sludge bulking control system, which will be controlled by the automatic control system in an emergency. Specifically: S31: Analyze the monitoring index of the physical state of sludge bulking and the monitoring system of the water quality analysis device at the outlet of the secondary sedimentation tank 4, comprehensively evaluate the degree of sludge bulking, and issue four different levels of early warning signals. The early warning levels are divided into high risk, relatively high risk, medium risk and general risk from high to low; High risk means abnormal water index, SVI ≥ 250 ml / g, SV30 ≥ 90%; Higher risk refers to normal water index, SVI ≥ 250 ml / g, SV30 ≥ 90%; Moderate risk refers to normal water index, 150 ml / g≤SVI≤250 ml / g, SV30≥80%; General danger means that the water index is normal, SVI≤150 ml / g, SV30≥80%, and the warning level signal is transmitted to the central control room and sludge bulking control system; S32: After receiving the warning signal, the sludge bulking control system issues process control or dosing instructions according to the risk level, specifically: When the risk is high, the frequency of sludge microscopic examination images is adjusted to once every 12 hours, the reflux of AOAO pool 3 is adjusted to 200%, and 100ppm of activated carbon is added; the reflux includes dosing reflux and / or sludge reflux, and the ratio is 1:5; the dosing reflux is a mixed sludge after the inorganic sludge and the sedimentation sludge are mixed, and the inorganic sludge is a floc composed of insoluble matter such as calcium carbonate, magnesium hydroxide, aluminosilicate, and a small amount of flocculant and coagulant aid, and the surface charge of the floc is positive, and the amount of inorganic sludge is 300ppm of the mixed sludge; At a higher risk level, the frequency of sludge microscopic examination images is adjusted to once every 24 hours, and the reflux of AOAO pool 3 is adjusted to 150%, and the reflux includes dosing reflux and / or sludge reflux, and the ratio is 1:5; the dosing reflux is a mixed sludge after the inorganic sludge and the sedimentation sludge are mixed, and the inorganic sludge is a floc composed of insoluble matter such as calcium carbonate, magnesium hydroxide, aluminosilicate, and a small amount of flocculant and coagulant aid, and the surface charge of the floc is positive, and the amount of inorganic sludge is 200ppm of the mixed sludge; At the medium hazard level, the frequency of sludge microscopic examination images is adjusted to once every 24 hours, and the AOAO pool 3 reflow is adjusted to 100%, and the reflow is only sludge reflow; When the general danger level is reached, the monitoring frequency of sludge settling index SV30 is adjusted to once every 12 hours; S33: After a period of regulation, the sludge bulking situation is alleviated, the early warning signal is lifted, the addition of sludge return, drug return and powdered activated carbon agent is stopped, and the process operation parameters are restored to the original designed normal operating parameters.

Claims

1. A sludge bulking early warning and control method for a coal chemical wastewater treatment system, characterized in that: The specific steps include: (1) Sewage inflow control: Mix qualified water and unqualified water and enter biochemical treatment; (2) Sludge physical state monitoring: monitoring the physical state indicators of sedimentation sludge and effluent water quality; (3) Sludge bulking warning and emergency control: Analyze and monitor the physical state indicators of the settled sludge and the effluent water quality to evaluate the degree of sludge bulking, and determine the warning level from high to low, divided into high risk, relatively high risk, medium risk and general risk; in the case of high risk, adjust the monitoring frequency, adjust the reflux rate to 200%, and add 100ppm of activated carbon; in the case of relatively high risk, adjust the monitoring frequency, adjust the reflux rate to 150%; in the case of medium risk, adjust the monitoring frequency, adjust the reflux rate to 100%, and in the case of general risk, adjust the monitoring frequency to restore the working conditions to normal; The reflux includes dosing reflux and / or sludge reflux, and the ratio is 1:5; the dosing reflux is mixed sludge obtained by mixing inorganic sludge with sedimentation sludge, and the inorganic sludge is flocs composed of insoluble matter such as calcium carbonate, magnesium hydroxide, aluminosilicate, and a small amount of flocculants and coagulants, and the surface charge of the flocs is positive; In the case of medium risk level, the reflux is only sludge reflux; in the case of high risk or relatively high risk level, the reflux is drug reflux and sludge reflux.

2. According to claim 1, the sludge bulking early warning and control method of the coal chemical wastewater treatment system is characterized in that: When the risk level is high or relatively high, the amount of inorganic sludge added to the dosing reflux is 300ppm and 200ppm of the mixed sludge respectively.

3. The sludge bulking early warning and control method of coal chemical wastewater treatment system according to claim 1 is characterized in that: The monitoring frequency adjustments during high risk, relatively high risk and medium risk are all based on the sludge microscopic examination image, and the monitoring frequencies are once every 12 hours, once every 24 hours and once every 24 hours respectively; the monitoring frequency adjustment during general risk is based on the sludge sedimentation index SV30, and the monitoring frequency is 12 hours.

4. The sludge bulking early warning and control method for coal chemical wastewater treatment system according to claim 1 is characterized in that: The sludge physical state indicators include sludge settling index SV30, sludge volume index SVI and sludge microscopic examination images; the sludge microscopic examination images include the growth of sludge filamentous bacteria, bacterial floc morphology and interstitial water clarity.

5. The sludge bulking early warning and control method of coal chemical wastewater treatment system according to claim 2 is characterized in that: The criteria for judging the warning level are as follows: High risk: abnormal water discharge index, SVI ≥ 250 ml / g, SV30 ≥ 90%; The higher risk: the water discharge index is normal, and SVI ≥ 250 ml / g, SV30 ≥ 90%; The medium risk: the water output index is normal, and 150 ml / g≤SVI≤250 ml / g, SV30≥80%; General danger: water output indicators are normal, with SVI ≤ 150 ml / g and SV30 ≥ 80%.

6. The sludge bulking early warning and control method for coal chemical wastewater treatment system according to claim 1 is characterized in that: The judgment of qualified water and unqualified water is as follows: S1: For incoming water, the online monitoring system analyzes water quality indicators every hour. If any of the indicators exceeds 20% and deviates from the design value by 20%, it is judged as unqualified incoming water; S2: When the incoming water is judged as unqualified, the water inlet valve of the regulating pool is immediately closed, and the water inlet valve of the unqualified pool is opened to temporarily store the unqualified incoming water; S3: Start the emergency mode and analyze the water quality index every 20 minutes until the index is qualified three times in a row, then return to the normal mode and judge the water as qualified; S4: Immediately close the water inlet valve of the unqualified water pool, open the water inlet valve of the regulating pool, and the sewage enters the regulating pool normally. The online monitoring system switches to normal mode and the analysis frequency is restored to once an hour.

7. The sludge bulking early warning and control method for coal chemical wastewater treatment system according to claim 6 is characterized in that: The unqualified water and the qualified water are mixed in a ratio of 1:10 to 3:

10.

8. A sludge bulking early warning and control system for a coal chemical wastewater treatment system, characterized in that: The system comprises a regulating tank, an unqualified water tank, an AOAO tank, a secondary sedimentation tank, and an accident tank, wherein the regulating tank and the unqualified water tank are connected in parallel and are connected in sequence to the AOAO tank, the secondary sedimentation tank, and the accident tank; The accident pool outlet is connected to the regulating pool inlet; The sludge outlet pipeline of the secondary sedimentation tank is connected to the AOAO tank return pipeline; The sludge outlet pipeline of the secondary sedimentation tank is connected to the sludge conditioning tank, and the inlet of the sludge conditioning tank is connected to the inorganic sludge storage tank; An activated carbon storage tank is also provided between the AOAO tank and the secondary sedimentation tank; The AOAO tank end and the secondary sedimentation tank are both provided with sludge state collection devices, and the regulating tank inlet and the secondary sedimentation tank outlet pipelines are both provided with water quality analysis devices.

9. The sludge bulking early warning and control system of the coal chemical wastewater treatment system according to claim 9 is characterized in that: The inlet of the regulating tank and the unqualified water tank are both provided with water inlet valves.

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