Activated sludge treatment system and method for enhancing sludge assimilation and reducing carbon dioxide emission

Abstract

The invention provides an activated sludge treatment system and a method for enhancing sludge assimilation and reducing carbon dioxide emission, and belongs to the technical field of sewage treatment. According to the activated sludge treatment system provided by the invention, by simultaneously monitoring real-time changes of O2, dissolved oxygen and CO2 under different aeration rates, the direct influence of the aeration rate on microbial metabolism efficiency is revealed, a dynamic association mechanism between the aeration rate and sludge assimilation and CO2 gas generation is established, the aeration rate can be accurately controlled, the emission of carbon dioxide is reduced, and the energy consumption is reduced. And energy is saved.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage treatment, and in particular relates to an activated sludge treatment system and a method for enhancing sludge assimilation and reducing carbon dioxide emissions. Background Art

[0002] The activated sludge process, a core process for biological wastewater treatment, degrades organic pollutants through microbial metabolism. However, its operation is associated with increasingly serious carbon dioxide (CO2) emissions. As global climate change intensifies, the wastewater treatment industry, a significant source of greenhouse gas emissions, urgently needs to explore low-carbon operation strategies. CO2 in the activated sludge process is primarily produced by microbial aerobic respiration, and its emission intensity is closely related to parameters such as aeration rate, organic matter loading, and sludge age. Traditional processes often employ excessive aeration to maintain high dissolved oxygen (DO) levels to ensure treatment efficiency. This not only increases energy consumption but also accelerates microbial metabolism, rapidly decomposing organic matter into CO2. Studies have shown that for every 100 mL / min increase in aeration rate, instantaneous CO2 emissions within the reactor increase by 15% to 20%. Furthermore, under long-term high aeration conditions, excessive oxidation by sludge microorganisms can trigger sludge disintegration, further releasing intracellular organic matter and exacerbating CO2 production.

[0003] In the existing technology, certain emission reduction effects have been achieved by optimizing aeration control (such as intermittent aeration and precise dissolved oxygen control), but it still faces the defect of inaccurate aeration volume control causing energy waste. Summary of the Invention

[0004] The object of the present invention is to provide an activated sludge treatment system and a method for enhancing sludge assimilation and reducing carbon dioxide emissions. By using the activated sludge treatment system provided by the present invention, by simultaneously monitoring the real-time changes of O2, dissolved oxygen (DO) and CO2 under different aeration rates, the direct impact of aeration rate on microbial metabolic efficiency is revealed, and a dynamic correlation mechanism between aeration rate, sludge assimilation and CO2 gas production is established. This can accurately control the aeration rate, reduce CO2 gas emissions, and save energy.

[0005] In order to achieve the purpose of the present invention, the present invention provides the following technical solutions:

[0006] An activated sludge treatment system comprises a timing device (1), an aeration device, a sludge concentration meter (3), a reactor, a gas sensor (7), a data monitoring device (9), a flow meter (10) and a water supply device (11);

[0007] The timing device (1) is electrically connected to the aeration device and is connected to the reactor via a pipeline;

[0008] The gas sensor (7) and the sludge concentration meter (3) are arranged in the reactor; the gas sensor (7) and the data monitoring device (9) are electrically connected;

[0009] The water supply device (11) is connected to the reactor inlet; the flow meter (10) is electrically connected between the water supply device (11) and the reactor.

[0010] Preferably, the reactor comprises a cylindrical container and a conical mud hopper from top to bottom; the side wall of the cylindrical container is provided with a drain port (8), and an agitator (5) is provided inside; the conical mud hopper is provided with a mud discharge port (6).

[0011] Preferably, the aeration device comprises an aeration pump (2) and an aeration disc (4) which are electrically connected; and the timing device (1), the aeration pump (2) and the aeration disc (4) are electrically connected in pairs.

[0012] The present invention also provides a method for enhancing sludge assimilation and reducing carbon dioxide emissions, comprising the following steps:

[0013] Inoculating and acclimating the activated sludge until the activated sludge treatment system described in the above technical solution operates stably;

[0014] Water from a water supply device is fed into a reactor and stirred, and the system in the reactor is aerobically aerated and water is continuously fed in, and data on the sludge concentration, gas production, and dissolved oxygen concentration of the system are obtained in real time. When the sludge concentration is 5000-6000 mg / L, the CO2 concentration is less than 2000 ppm, and the dissolved oxygen concentration is 0-8 mg / L, water feeding and aeration are stopped, the aeration time is recorded, and the next aeration time is controlled by a timing device to achieve control of the aeration amount; the aeration intensity of the aerobic aeration is 500 mL / min;

[0015] After aerobic aeration is completed, sedimentation and drainage are carried out.

[0016] Preferably, the sludge settling ratio of the pretreated activated sludge is 28% to 40%.

[0017] Preferably, during the aerobic aeration, the water filling ratio of the reactor is 0.5-0.8, the sludge level is 10-12 cm, and the dead water level is 13.3 cm.

[0018] Preferably, the aerobic aeration time is 6 to 12 hours.

[0019] Preferably, the water inlet flow rate in the aeration stage is 5 to 10 L / h, and the water inlet time is 1 to 3 hours;

[0020] The precipitation time is 1 to 3 hours.

[0021] Preferably, during the drainage process, sludge is discharged when the sludge concentration after aerobic aeration in the reactor exceeds 5000 mg / L.

[0022] The present invention provides an activated sludge treatment system, characterized in that it includes a timing device (1), an aeration device, a sludge concentration meter (3), a reactor, a gas sensor (7), a data monitoring device (9), a flow meter (10) and a water supply device (11); the timing device (1) and the aeration device are electrically connected and connected to the reactor through a pipeline; the gas sensor (7) and the sludge concentration meter (3) are arranged in the reactor; the gas sensor (7) and the data monitoring device (9) are electrically connected; the water supply device (11) is connected to the reactor inlet; and the flow meter (10) is electrically connected between the water supply device (11) and the reactor. The present invention realizes the direct influence of aeration on microbial metabolic efficiency (such as organic matter degradation rate) by designing an integrated reactor and monitoring the change of sludge concentration, dissolved oxygen concentration and CO2 emission in the reactor in real time, and simultaneously tracks the real-time changes of O2, DO and CO2 under different aeration rates, thereby establishing a dynamic correlation mechanism between aeration rate and sludge assimilation and gas production. Combining peak CO2 levels with the long-term evolution of sludge concentration reveals that high aeration rates lead to microbial overoxidation, decreased sludge concentration, and, over time, loose sludge structure. Low aeration rates also lead to low DO utilization and CO2 accumulation, providing a theoretical basis for optimizing aeration rates. This study proposes an aeration rate of 500 mL / min as the optimal operating condition, balancing CO2 emission control, sludge assimilation, and energy efficiency, maximizing activated sludge assimilation and reducing CO2 emissions from microbial metabolism. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 Schematic diagram of the structure of the aeration regulating device of the present invention, wherein 1-timing device, 2-aeration pump, 3-sludge concentration meter, 4-aeration disc, 5-agitator, 6-sludge outlet, 7-gas sensor, 8-drain outlet, 9-data monitoring device, 10-flow meter, 11-water supply device;

[0025] Figure 2 The sludge concentration changes of the reactor under long-term operation under different aeration rates;

[0026] Figure 3CO2 changes in the reactor during long-term operation under different aeration rates;

[0027] Figure 4 The change of O2 proportion during the operation cycle under different aeration rates;

[0028] Figure 5 The DO changes during the operation cycle under different aeration rates. DETAILED DESCRIPTION

[0029] The present invention provides an activated sludge treatment system, comprising a timing device (1), an aeration device, a sludge concentration meter (3), a reactor, a gas sensor (7), a data monitoring device (9), a flow meter (10) and a water supply device (11);

[0030] The timing device (1) is electrically connected to the aeration device and is connected to the reactor via a pipeline;

[0031] The gas sensor (7) and the sludge concentration meter (3) are arranged in the reactor; the gas sensor (7) and the data monitoring device (9) are electrically connected;

[0032] The water supply device (11) is connected to the reactor inlet; the flow meter (10) is electrically connected between the water supply device (11) and the reactor.

[0033] In the present invention, the timing device (1) can be a timer; the present invention controls the running time of each stage through the timing device.

[0034] In the present invention, the aeration device comprises an aeration pump (2) and an aeration disc (4) which are electrically connected; the timing device (1), the aeration pump (2) and the aeration disc (4) are electrically connected in pairs.

[0035] In the present invention, the reactor comprises a cylindrical container and a conical mud hopper from top to bottom; the side wall of the cylindrical container is provided with a drain port (8), and an agitator (5) is provided inside; the conical mud hopper is provided with a mud discharge port (6); the present invention has no special restrictions on the height and diameter of the cylindrical container and the conical mud hopper. In a specific embodiment, the height of the cylindrical container can be 40 cm and the diameter can be 25 cm, and the height of the conical mud hopper can be 40 cm and the diameter can be 25 cm.

[0036] In the present invention, two circular holes are provided on the top of the cylindrical container, into which a sludge concentration meter (3) and a gas sensor (7) are inserted respectively; the gaps of the circular holes are sealed with aluminum foil; and the rest of the reactor of the present invention is in a sealed state.

[0037] In the present invention, the flow meter (10) may be a rotor flow meter, and the water supply device (11) may be a water tank, wherein the water tank further comprises a water pump; the flow meter is used to measure the water inlet flow in the water supply device.

[0038] The present invention also provides a method for enhancing sludge assimilation and reducing carbon dioxide emissions, comprising the following steps:

[0039] Inoculating and acclimating the activated sludge until the activated sludge treatment system described in the above technical solution operates stably;

[0040] Water from a water supply device is fed into a reactor and stirred, and the system in the reactor is aerobically aerated and water is continuously fed, and data on the sludge concentration, gas production, and dissolved oxygen concentration of the system are obtained in real time; when the sludge concentration is 5000-6000 mg / L, the CO2 concentration is less than 2000 ppm, and the dissolved oxygen concentration is 0-8 mg / L, water feeding and aeration are stopped, the aeration time is recorded, and the next aeration time is controlled by a timing device to achieve control of the aeration volume; the aerobic aeration volume is 500 mL / min;

[0041] After aerobic aeration is completed, sedimentation and drainage are carried out.

[0042] The present invention performs inoculation and acclimation on activated sludge until the activated sludge treatment system described in the above technical solution operates stably. In the present invention, the activated sludge is derived from activated sludge in aerobic tanks of a sewage treatment plant and has a sludge age of 5 to 15 days. The inoculation and acclimation method is aeration, and the present invention does not specifically limit the inoculation and acclimation conditions. The sludge settling ratio of the pretreated activated sludge is 28% to 40%. The present invention removes residual organic matter (COD, nitrogen compounds, and phosphorus compounds) in the activated sludge through inoculation and acclimation.

[0043] After obtaining pretreated activated sludge, the present invention introduces water from a water supply device into a reactor and stirs it. Aerobically aerates the system within the reactor while continuously adding water, acquiring real-time data on the sludge concentration, gas production, and dissolved oxygen concentration. In the present invention, the reactor has a water filling ratio of 0.5 to 0.8, a sludge level of 10 to 12 cm, and a dead water level of 13.3 cm. The water flow rate is 5 to 10 L / h, and the water inlet time is 0.5 to 1 hour. The agitator speed is 50 to 100 rpm.

[0044] In the present invention, the pH value during aerobic aeration is 6.5-8, and the temperature is room temperature, and in a specific embodiment, it can be 25°C.

[0045] In the present invention, when the sludge concentration is 5000-6000 mg / L, the CO2 concentration is less than 2000 ppm, and the dissolved oxygen concentration is 0-8 mg / L, water inflow and aeration are stopped, the aeration time is recorded, and the next aeration time is controlled by a timing device to control the aeration volume. In the present invention, the aeration intensity of the aerobic aeration is 500 mL / min; the aerobic aeration time is 6-12 hours, and in a specific embodiment, it can be 6 hours.

[0046] In the present invention, the precipitation time is 1 to 3 hours.

[0047] In the present invention, during the drainage process, sludge is discharged when the sludge concentration after aerobic aeration in the reactor exceeds 5000 mg / L.

[0048] To further illustrate the present invention, the activated sludge treatment system and the method for enhancing sludge assimilation and reducing carbon dioxide emissions provided by the present invention are described in detail below in conjunction with the accompanying drawings and examples, but they should not be understood as limiting the scope of protection of the present invention.

[0049] Example 1

[0050] After the activated sludge was allowed to settle at room temperature for 12 hours, the supernatant was poured out, and then the activated sludge was exposed to the sun at room temperature for 24 hours to remove the residual organic matter, and then washed three times. Figure 1 The activated sludge treatment system is assembled according to the structural diagram of the activated sludge treatment system. The cleaned activated sludge is transferred to the reactor of the activated sludge treatment system. According to the set cycle of the reactor, the normal operation of the sewage is simulated. During this period, the COD and ammonia nitrogen (NH 4+ -N) and phosphate (as PO4 3- When the activated sludge changes to a yellow-brown color, microscopic examination shows that the sludge flocs become larger and have clearer edges, the structure of the bacterial flocs is tight, there are more protozoa, and the sedimentation performance becomes good. At this point, the activated sludge can be considered to have been domesticated and matured. During this period, all water quality indicators meet the design requirements, the activated sludge concentration (MLSS) in the reactor is maintained at 4500-6000 mg / L, and the sludge settling ratio (SV30) is maintained at 28-40%. When the activated sludge treatment system is running stably, pre-treated activated sludge can be obtained.

[0051] The water in the water tank is input into the reactor at a water inlet of 10 L / h. The agitator is turned on while the water is being input. The agitator speed is 100 rpm. The water is input for 1 hour. The water filling ratio in the reactor is 0.5, the sludge level is 10-12 cm, and the dead water level is 13.3 cm.

[0052] After the water inflow is completed, the aeration pump is turned on and three aeration rates of 400mL / min, 500mL / min, and 600mL / min are selected to provide different aeration rates in the reactor. The data from the sludge concentration meter, gas sensor, and data monitoring device are monitored in real time. The minimum CO2 production, the maximum O2 utilization rate, and the maximum assimilation of sludge under these conditions are selected. The aeration device and water tank are closed, the aeration time is recorded, and the next aeration time is controlled by a timer to achieve control of the aeration rate.

[0053] After aerobic aeration is completed, sedimentation is carried out for 1 hour. After sedimentation is completed, the drain outlet is opened to drain water, and then standby for 1 hour for the next activated sludge assimilation.

[0054] Example 1 Result Analysis

[0055] (1) Sludge assimilation capacity

[0056] After the reactor has been running for a certain period of time at different aeration rates, the concentration of activated sludge in the reactor changes with the running time. Figure 2 As shown, activated sludge concentrations remained high over extended periods under all three aeration conditions. At an aeration rate of 400 mL / min, activated sludge concentrations were lower than at 500 and 600 mL / min, suggesting that low aeration rates may have limited microbial growth and reproduction. The microbial biomass remained relatively stable throughout the operation. At an aeration rate of 500 mL / min, activated sludge concentrations generally increased from day 1 to day 15, rising from an initial value of 5081 mg / L to 6248 mg / L. This suggests that activated sludge microorganisms were well adapted to these conditions, maintaining stable survival and increasing assimilation. However, at an aeration rate of 600 mL / min, activated sludge concentrations increased significantly only between days 1 and 5, then gradually decreased from 5872 mg / L to 4838 mg / L. This may be due to the high aeration rate in the later stages of operation, which maintained a high DO level for a prolonged period, leading to excessive oxidation of the sludge microorganisms and a decrease in sludge biomass, indicating a decrease in microbial biomass.

[0057] (2) CO2 emissions

[0058] After the reactor was operated for a certain period of time at different aeration rates, the CO2 content in one cycle showed a trend of first increasing and then decreasing, such as Figure 3As shown, the CO2 content in the reactor at 400 mL / min fluctuated less than at 500 mL / min and 600 mL / min, and decreased more slowly. This was primarily due to the low aeration rate and the slow decomposition of organic matter. Microorganisms continuously utilized the DO in the water for dissimilation and continuously released CO2, maintaining a high CO2 level throughout the cycle. This correlates with the relatively slow change in DO. However, the CO2 content in the reactor increased and decreased more rapidly at aeration rates of 600 mL / min and 500 mL / min, indicating that the microorganisms in the sludge decomposed rapidly, enabling pollutant degradation to be completed in a shorter time. Once organic matter degradation in the wastewater was complete, the CO2 content in the reactor decreased rapidly as aeration continued, while the O2 content recovered rapidly. Furthermore, the CO2 peak in the reactor at 600 mL / min was higher than at 500 mL / min, indicating that the activated sludge underwent more dissimilation, resulting in the production of more CO2.

[0059] (3) O2 utilization rate

[0060] After the reactor was operated for a certain period of time at different aeration rates, the oxygen utilization rate and DO in the activated sludge mixed liquor in one operation cycle showed similar trends. Figure 4 and Figure 5 As shown in the figure, the average O2 content in the reactor was highest at an aeration rate of 600 mL / min and lowest at 400 mL / min, with a significant difference between the two. At an aeration rate of 600 mL / min, the O2 content in the reactor began to recover earlier than at both 500 mL / min and 400 mL / min, and the recovery rate was the fastest. Furthermore, the activated sludge DO remained consistently higher at an aeration rate of 600 mL / min compared to 400 mL / min and 500 mL / min. This is because when activated sludge microorganisms utilize DO to decompose organic matter, the more abundant O2 provided by the aeration rate of 600 mL / min results in a higher DO level in the water. This allows the microorganisms to degrade the organic matter in a shorter period of time. Once the degradation process is complete, the aeration rate remains high, leading to a rapid recovery of O2 in the reactor. This process also maintains a high DO level in the activated sludge. The aeration volume of 400mL / min and 500mL / min is slightly smaller, and the DO level is relatively low. Therefore, it takes longer for microorganisms to decompose organic matter. Especially when the aeration volume is 400mL / min, the time for O2 to recover in the reactor is significantly delayed, and the overall O2 proportion is lower than 500mL / min and 600mL / min, and the rise and consumption rate of DO is slower.

[0061] Although the above embodiment provides a detailed description of the present invention, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. An activated sludge treatment system, characterized in that: It includes a timing device (1), an aeration device, a sludge concentration meter (3), a reactor, a gas sensor (7), a data monitoring device (9), a flow meter (10) and a water supply device (11); The timing device (1) is electrically connected to the aeration device and is connected to the reactor via a pipeline; The gas sensor (7) and the sludge concentration meter (3) are arranged in the reactor; the gas sensor (7) and the data monitoring device (9) are electrically connected; The water supply device (11) is connected to the reactor inlet; the flow meter (10) is electrically connected between the water supply device (11) and the reactor.

2. The activated sludge treatment system according to claim 1, characterized in that: The reactor comprises a cylindrical container and a conical mud hopper from top to bottom; a drain port (8) is provided on the side wall of the cylindrical container, and an agitator (5) is provided inside the cylindrical container; and a mud discharge port (6) is provided in the conical mud hopper.

3. The activated sludge treatment system according to claim 1 or 2, characterized in that: The aeration device comprises an aeration pump (2) and an aeration disc (4) which are electrically connected; the timing device (1), the aeration pump (2) and the aeration disc (4) are electrically connected in pairs.

4. A method for enhancing sludge assimilation and reducing carbon dioxide emissions, characterized in that: The following steps are involved: Inoculating and acclimating the activated sludge until the activated sludge treatment system according to any one of claims 1 to 3 operates stably; Water from a water supply device is fed into a reactor and stirred, and the system in the reactor is aerobically aerated and water is continuously fed in, and data on the sludge concentration, gas production, and dissolved oxygen concentration of the system are obtained in real time. When the sludge concentration is 5000-6000 mg / L, the CO2 concentration is less than 2000 ppm, and the dissolved oxygen concentration is 0-8 mg / L, water feeding and aeration are stopped, the aeration time is recorded, and the next aeration time is controlled by a timing device to achieve control of the aeration amount; the aeration intensity of the aerobic aeration is 500 mL / min; After aerobic aeration is completed, sedimentation and drainage are carried out.

5. The method according to claim 4, characterized in that The sludge settling ratio of the pretreated activated sludge is 28% to 40%.

6. The method according to claim 4, characterized in that During the aerobic aeration, the water filling ratio of the reactor is 0.5-0.8, the sludge level is 10-12 cm, and the dead water level is 13.3 cm.

7. The method according to claim 4, characterized in that The aerobic aeration time is 6 to 12 hours.

8. The method according to claim 4, characterized in that The water inlet flow rate in the aeration stage is 5 to 10 L / h, and the water inlet time is 1 to 3 hours; The precipitation time is 1 to 3 hours.

9. The method according to claim 4, characterized in that During the drainage process, sludge is discharged when the sludge concentration after aerobic aeration in the reactor exceeds 5000 mg / L.

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