Medium and high concentration organic wastewater treatment method and system based on aerobic granular sludge

Abstract

The invention relates to the technical field of sewage treatment, and discloses a medium-high concentration organic wastewater treatment system based on aerobic granular sludge, which comprises an AGS device, an aeration system, a uniform water distributor, a sludge discharge system, a water decanter and an intelligent control unit (AGS control equipment and an online instrument), the invention also discloses a medium-high concentration organic wastewater treatment method based on aerobic granular sludge, which comprises the following steps: S1, intensifying a biological phosphorus release process and avoiding short flow of effluent in a manner of firstly decanting water quickly and then supplementing water slowly; s2, the duration of each cycle period is 6-12 hours; s3, multi-parameter coupling of organic matter volume load, sludge load, inlet and outlet water quality and treated water quantity is carried out to realize rapid starting of the device and sludge granulation; and S4, in the aeration stage, gradient control is performed on the dissolved oxygen value. S5, discharging sludge in stages; according to the invention, the sludge concentration can be maintained between 10 g / L and 18 g / L, the average particle size of the sludge is greater than 0.2 mm, the average particle size is maintained and stabilized at about 20 mL / g, and high-concentration organic wastewater with the COD value of 800-3000 mg / L can be treated within extremely short hydraulic retention time.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a method and system for treating medium-to-high concentration organic wastewater based on aerobic granular sludge. Background Technology

[0002] Wastewater treatment refers to the process of removing or degrading pollutants, harmful substances, and pathogens from domestic sewage, industrial wastewater, and other polluted water bodies through physical, chemical, and biological methods, thereby purifying the water to meet reuse standards or allowing it to be safely discharged into natural water bodies (rivers, lakes, and oceans) without causing environmental pollution.

[0003] In existing technologies, aerobic or anaerobic methods can be used to treat COD values ​​in the range of 800-3000 mg / L, but both of these processes have certain limitations, whether used alone or in combination.

[0004] If an anaerobic process is used, a nitrogen and phosphorus removal unit needs to be added in the later stage. At the same time, due to the full degradation of organic matter in the anaerobic stage, the carbon source of the nitrogen and phosphorus removal unit is often insufficient, and additional carbon source needs to be added. Furthermore, the anaerobic process is prone to sludge floating, which in turn increases the burden on subsequent treatment units. If only aerobic processes are used, a longer hydraulic retention time is required to ensure that the water quality meets the standards. The hydraulic retention time is usually greater than 24 hours, and in some cases even greater than 48 hours. An excessively long hydraulic retention time (HRT) means that a larger footprint or a larger effective volume of equipment is required, which will significantly increase the investment and construction costs, resulting in excessively high overall wastewater treatment costs and excessively low volumetric load.

[0005] Based on the above technical challenges, we propose a method and system for treating medium-to-high concentration organic wastewater based on aerobic granular sludge. This method uses a pure aerobic biological treatment method to treat high-concentration organic wastewater with COD values ​​of 800-3000 mg / L under extremely short hydraulic retention time. Summary of the Invention

[0006] The purpose of this invention is to provide a method and system for treating medium-to-high concentration organic wastewater based on aerobic granular sludge technology, which can maintain a sludge concentration between 10-18 g / L and an average sludge particle size greater than 0.2 mm. It stabilizes at around 20 mL / g and can treat high-concentration organic wastewater with COD values ​​of 800-3000 mg / L within a very short hydraulic retention time, thus solving the problems mentioned in the background technology.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a medium-to-high concentration organic wastewater treatment system based on aerobic granular sludge, comprising: AGS unit is used to hold a mixture of sludge and wastewater. The aeration system, installed at the bottom of the AGS unit, provides aeration and mixing to the wastewater inside the AGS unit; A uniform water distributor, installed at the bottom of the AGS unit, is used to replenish wastewater into the interior of the AGS unit; The sludge discharge system, installed in the middle of the AGS unit, is used to discharge small-particle sludge. The decanter, installed in the middle of the AGS unit, is used to drain the supernatant that has been processed inside the AGS unit. The intelligent control unit includes an AGS control device and an online instrument. The intelligent control unit is also equipped with an embedded control program that controls the start and stop of the AGS control device based on the data from the online instrument.

[0008] Preferably, the AGS device is circular or rectangular in shape, with a total height of 7 meters and an effective water depth of 6.5 meters.

[0009] Preferably, the AGS control equipment includes a water pump installed on the inlet pipe, multiple electric valves installed on the decanter pipe and the sludge discharge system pipe, and a blower for aerating the wastewater.

[0010] Preferably, the online instruments include an online dissolved oxygen meter, an online level gauge, an online thermometer, an online ammonia nitrogen meter, and an online sludge interface meter.

[0011] This invention also provides a method for treating medium-to-high concentration organic wastewater based on aerobic granular sludge. The method employs the aforementioned aerobic granular sludge-based system for treating medium-to-high concentration organic wastewater, and includes the following steps: S1. During the commissioning period, gradually increase the cycle water exchange ratio to shorten the hydraulic retention time (HRT) to 12 hours or reach the designed treatment capacity. Use a fast decanting and slow replenishment method in each cycle to enhance biological phosphorus removal and avoid short-circuiting of the effluent. S2. An operating cycle with a duration of 6, 8, or 12 hours is adopted. Each operating cycle includes: water replenishment, anaerobic digestion, aeration, sedimentation, and decanting. The aeration time is more than 60% of the total operating cycle time. S3. The coupling of multiple parameters, including organic volumetric loading, sludge loading, and influent and effluent water quality, enables rapid process commissioning and sludge granulation. S4. During the aeration stage, the dissolved oxygen value is controlled by gradient. S5. Staged sludge discharge achieves rapid sludge screening and maintains a high sludge concentration, ensuring the average sludge particle size is greater than 0.2mm through screening. Less than 35 mL / g.

[0012] Preferably, in step S3, sludge is inoculated at the initial stage of AGS device startup. The amount of water replenished per cycle is determined by the volumetric load and sludge load. When the COD and total nitrogen in the decanting water quality indicators are lower than the design discharge requirements, the water exchange ratio for each operating cycle is increased by 20%-30% to increase the daily treatment capacity. The larger the daily treatment capacity, the smaller the hydraulic retention time (HRT) is, until the hydraulic retention time (HRT) is reduced to 12 hours or reaches the design treatment scale.

[0013] Preferably, in step S2, the 8-hour operating cycle includes the following processes: water replenishment for 80 minutes, anaerobic digestion for 10 minutes, aeration for 310 minutes, sedimentation for 50 minutes, and decanting for 30 minutes. During the water inlet stage, the wastewater to be treated is pumped into the AGS device, and water is replenished into the AGS device through a uniform water distributor. The amount of water replenished in each operating cycle is the same as the amount of water decanted, and decanting is performed before water replenishment.

[0014] Preferably, in step S5, This reflects the settling properties of the sludge. The sludge granulation process is complete when the sludge concentration is less than 50 mL / g and the average particle size is greater than 0.2 mm. To maintain a high sludge concentration, in... When the sludge concentration is less than 50 mL / g and the average particle size is greater than 0.2 mm, sludge discharge should be suspended until the sludge concentration rises to 15-18 g / L. Within this range, the sludge settling ratio should be within 30 minutes. Not exceeding 0.45 No sludge is discharged when the concentration is below 40 mL / g.

[0015] Preferably, in step S4, the operating frequency or start / stop of the blower is controlled by the embedded control program, so that the dissolved oxygen does not exceed 0.2 mg / L in the first 30% of the aeration period, the dissolved oxygen is not lower than 2 mg / L in the last 15% of the aeration period, and the dissolved oxygen is maintained between 0.5-1 mg / L in the middle stage of aeration.

[0016] Compared with the prior art, the beneficial effects of the present invention are: This invention can maintain a sludge concentration between 10-18 g / L and an average sludge particle size greater than 0.2 mm. With a COD value of around 20 mL / g, the pure aerobic method can treat high-concentration organic wastewater with a COD value of 800-3000 mg / L to the Class A discharge level of the "Discharge Standard of Pollutants for Urban Wastewater Treatment Plants" within a very short hydraulic retention time (12-18 h), achieving economical, energy-saving and efficient treatment of medium and high concentration organic wastewater. Attached Figure Description

[0017] Figure 1This is a flowchart of the present invention; Figure 2 This is a line graph showing the changes in sludge concentration and sludge settling index according to the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Please see Figure 1-2 This invention provides a technical solution: a medium-to-high concentration organic wastewater treatment system based on aerobic granular sludge, which solves the dilemma of treating medium-to-high concentration organic wastewater (COD value between 800-3000 mg / L) by using a pure aerobic biological treatment method under extremely short hydraulic retention time.

[0020] include: AGS unit is used to hold a mixture of sludge and wastewater. The aeration system, installed at the bottom of the AGS unit, provides aeration and mixing to the wastewater inside the AGS unit; Specifically, the aeration system includes aeration discs, which are installed at the bottom of the AGS device.

[0021] A uniform water distributor, installed at the bottom of the AGS unit, is used to replenish wastewater into the interior of the AGS unit; The sludge discharge system is installed in the middle of the AGS unit to discharge small-diameter sludge. The sludge discharge port of the sludge discharge system is located 2 meters below the liquid surface of the AGS unit and is connected to an external pipeline. The pipeline is equipped with an electric valve and a flow meter. The decanter, installed in the middle of the AGS unit, is used to drain the supernatant that has been treated inside the AGS unit; different decanting heights are set according to water exchange ratios of 30%, 40%, 50%, and 60%. The intelligent control unit includes an AGS control device and an online instrument. The intelligent control unit is also equipped with an embedded control program that controls the start and stop of the AGS control device based on the data from the online instrument.

[0022] The AGS device is circular or rectangular in shape, with a total height of 7 meters and an effective water depth of 6.5 meters.

[0023] The AGS control equipment includes a water pump installed on the inlet pipe, multiple electric valves installed on the decanter pipe and the sludge discharge system pipe, a variable frequency lift pump installed on the water pipe, and a blower for aerating the sewage.

[0024] The online instruments include an online dissolved oxygen meter, an online level gauge, an online thermometer, an online ammonia nitrogen meter, and an online sludge interface meter.

[0025] The online dissolved oxygen (DO) meter, online ammonia nitrogen (AM) meter, and blower are jointly controlled to achieve efficient and stable operation. The intelligent control unit controls the start, stop, frequency reduction, and frequency increase of the blower based on the real-time online DO and AM values. During the first 30% of the aeration period, DO is maintained below 0.5 mg / L to create an anaerobic environment. During the last 15% of the aeration period, DO is maintained above 2 mg / L. When the DO value falls below 1.5 mg / L, the blower frequency is increased to increase the air supply, ensuring the DO value remains above 2 mg / L and guaranteeing complete conversion of ammonia nitrogen. During the intermediate aeration phase, the DO value is maintained around 0.5-1 mg / L. When the DO value is too high or too low, the blower frequency is reduced or increased. This ensures effective removal of pollutants while minimizing unnecessary aeration energy consumption.

[0026] Furthermore, the online dissolved oxygen meter monitors the real-time concentration of dissolved oxygen in the wastewater within the AGS device. As the core signal for the automatic control of the aeration system, the online dissolved oxygen meter maintains DO within the set range, ensuring efficient degradation of organic matter and nitrification of ammonia nitrogen by aerobic microorganisms, while avoiding energy waste or sludge aging caused by over-aeration.

[0027] Online level gauge: continuously measures the sewage level in the AGS device to control the automatic start and stop of the water pump and prevent sewage overflow or water pump dry running; Online thermometers: These monitor the temperature of wastewater in real time, as temperature directly affects the metabolic rate and population structure of microorganisms. Most wastewater treatment microorganisms thrive at temperatures between 20-35°C. Temperatures that are too low significantly reduce treatment efficiency, while temperatures that are too high may lead to sludge bulking or microbial death.

[0028] Online ammonia nitrogen meter: Real-time monitoring of ammonia nitrogen concentration in wastewater; Online sludge interface meter: continuously measures the interface height between the sludge layer and the supernatant during the sedimentation stage. The data from the sludge interface meter is used to control the optimal height of the decanter, ensuring clear effluent and preventing sludge loss.

[0029] The present invention also provides a method for treating medium- and high-concentration organic wastewater based on aerobic granular sludge, which adopts the above-described aerobic granular sludge-based medium- and high-concentration organic wastewater treatment system and uses AGS technology for wastewater treatment. AGS technology is a biological treatment process based on aerobic methods, simultaneously removing nitrogen and phosphorus. This process requires only one rotating device—a blower—when treating wastewater. Compared to existing aerobic technologies, it eliminates the need for internal and external recirculation systems, mixing systems, sludge scrapers, and secondary sedimentation tanks. It saves over 40% of floor space and reduces power consumption by over 45%, making it a more efficient, energy-saving, and economical wastewater treatment technology.

[0030] Includes the following steps: S1. During the commissioning period, gradually increase the cycle water exchange ratio to shorten the hydraulic retention time (HRT) to 12 hours. Use a fast decanting and slow replenishment method in each cycle to enhance biological phosphorus removal and avoid short-circuiting of the effluent. The fast decanting and slow replenishment method means that decanting is completed within 30 minutes and replenishment is completed within 80 minutes in each cycle.

[0031] Sludge is inoculated during the initial startup of the AGS unit. The amount of water replenished per cycle is determined by the sludge load and volumetric load. When the COD and total nitrogen in the decanting water quality indicators are lower than the design discharge requirements, the water exchange ratio per cycle is increased by 20%-30% to increase the daily treatment capacity. The larger the daily treatment capacity, the smaller the hydraulic retention time (HRT) is, until the HRT is reduced to 12 hours or the design treatment capacity is reached.

[0032] The hydraulic retention time (HRT) is the ratio between the effective volume of the AGS unit and the daily processing capacity, and the water exchange ratio is the ratio between the decanting volume of each operating cycle and the effective volume of the AGS unit.

[0033] S2. An operating cycle with a duration of 6-12 hours is adopted. Each operating cycle includes the following stages: water replenishment, anaerobic digestion, aeration, sedimentation, and decanting. The aeration time is more than 60% of the total operating cycle time. To avoid prolonged endogenous respiration of microorganisms after pollutants have been completely degraded in the latter part of each cycle, which could affect microbial proliferation or result in insufficient degradation of organic matter, the duration of each cycle is adjusted according to the COD value of the wastewater. When the COD value of the wastewater is in the range of 800-1200 mg / L, 1200-2000 mg / L, and 2000-3000 mg / L, the total duration of each cycle is 6h, 8h, and 12h, respectively. The aeration duration within each cycle is 200min, 310min, and 550min, respectively. The water replenishment duration of each cycle is 80min, the decanting duration of each cycle is 30min, the sedimentation stage duration is 30min or 40min, and the anaerobic stage duration during the start-up and commissioning period is 10min or 20min. The 8-hour operating cycle includes the following processes: 80 minutes of water replenishment, 10 minutes of anaerobic digestion, 310 minutes of aeration, 50 minutes of sedimentation, and 30 minutes of decanting. During the water inlet stage, the wastewater to be treated is pumped into the AGS device, and water is replenished into the AGS device through a uniform water distributor. The amount of water replenished in each operating cycle is the same as the amount of water decanted, and decanting is performed before water replenishment. By decanting for 30 minutes and replenishing with water for 80 minutes, the high-concentration wastewater short-circuiting can be avoided from affecting the effluent quality. At the same time, the replenishment stage is anaerobic, which can enhance the anaerobic phosphorus release process of microorganisms. Furthermore, decanting should be done before replenishing water, because the wastewater to be treated has a high concentration of pollutants and the replenishment time is long. If a simultaneous inflow and outflow mode is adopted, the water is prone to mixing, and there is a risk that the effluent water quality will exceed the standard.

[0034] S3, Organic Volumetric Loading sludge load Influent and effluent water quality (mg / L), treated water volume Multi-parameter coupling enables rapid process commissioning and sludge granulation.

[0035] During the initial startup phase, ordinary activated sludge is inoculated into the device, preferably using secondary sedimentation tank waste sludge with a higher concentration (approximately 8-10 g / L). The amount of inoculated sludge is calculated as follows: (1) in, Indicates the volume of residual sludge after inoculation. , V represents the concentration (g / L) of sludge after inoculation within the device, and V represents the effective volume of the device. , This indicates the concentration of residual sludge (g / L).

[0036] After the sludge inoculation is completed, water is added to the device. The device is officially started and enters the commissioning stage from the first water addition. The calculation method for the water addition amount per cycle is shown in formula (2) and formula (3).

[0037] (2) (3) The amount of water replenishment on the first day of startup is determined by formulas (2) and (3). and Substitute 0.1 and 1 into the values ​​to calculate Q. Take the minimum value of Q calculated by the two formulas. This flow rate is the daily processing volume during the initial commissioning phase. Divide this value by the number of daily cycles to get the water replenishment volume per cycle.

[0038] Where Q represents the daily processing volume. , This indicates the organic sludge load (kgCOD / kgMLSS / d). This indicates the sludge concentration (g / L) within the device. This represents the difference (g / L) in COD values ​​between the influent and effluent. Indicates the effective volume of the device .

[0039] Water quality indicators are measured daily using decanted water, and sludge concentration is measured during the aeration phase using mixed sludge-water samples. When the effluent COD and total nitrogen (TN) concentrations are both lower than the design discharge requirements, the influent volume for the current cycle is increased by 20%-30%, and the corresponding decanting volume for each cycle is also increased. This process is repeated, gradually increasing the makeup water volume for each cycle until the treatment capacity gradually reaches the design treatment scale.

[0040] When the effluent COD and total nitrogen are both lower than the design discharge requirements, increase the influent volume by 20%-30% based on the current cycle. S4. During the aeration stage, the dissolved oxygen value is controlled by gradient.

[0041] The embedded control program controls the operating frequency or start / stop of the blower, ensuring that the dissolved oxygen (DO) in the mud-water mixture in the device does not exceed 0.2 mg / L during the first 30% of the aeration phase, does not fall below 2 mg / L during the last 15% of the aeration phase, and maintains the dissolved oxygen between 0.5 and 1 mg / L during the middle stage of aeration.

[0042] It is worth noting that when DO does not exceed 0.2 mg / L, the phosphorus-removing microorganisms in the device can fully release phosphorus under anaerobic conditions, while ensuring that the sludge flocs can fully adsorb organic matter in the wastewater, thereby ensuring the carbon and phosphorus removal effect. When DO does not exceed 0.5 mg / L, the minimum oxygen demand required for the nitrification process can be guaranteed, avoiding excessive aeration and energy waste. At the same time, the DO level of not exceeding 0.5 mg / L creates conditions for simultaneous nitrification and denitrification.

[0043] When DO remains low throughout each cycle, some areas within the system may experience insufficient oxygen supply or anaerobic conditions, or incomplete nitrification, which is detrimental to the stable operation of the system. Once the nitrification of ammonia nitrogen is complete, the sludge will no longer consume oxygen, at which point DO will increase significantly. An increase or sudden rise in DO is typically used as a reference value for complete ammonia nitrogen degradation. Therefore, it is necessary to ensure that the DO value is greater than 2 mg / L within 30 minutes before the end of aeration.

[0044] In a specific application, an AGS device with an effective volume of 65 cubic meters was built in the wastewater treatment plant of a starch processing park. After stable operation, the daily treatment capacity was 129 tons / day.

[0045] The wastewater received by the plant flows into multiple equalization tanks, including high-concentration equalization tanks and low-concentration equalization tanks, with COD values ​​of approximately 4000 mg / L and 800 mg / L, respectively.

[0046] The effluent from the high-concentration equalization tank and the low-concentration equalization tank is introduced into the AGS device. The COD value entering the AGS device is controlled by adjusting the ratio of high-concentration and low-concentration wastewater.

[0047] In the initial stage of startup, sludge from the aerobic biochemical section of the plant was inoculated, with a sludge concentration of 5-6 g / L. Wastewater with a COD value greater than 1500 mg / L was introduced into the AGS unit. The initial hydraulic retention time was set to 36 h, and the water exchange ratio per cycle was 0.18.

[0048] Closely monitor the daily pollutant removal efficiency and sludge concentration. While ensuring the sludge load does not exceed 0.25 kg COD / kg MLSS / d, gradually increase the water exchange ratio per cycle. By increasing the water exchange ratio per cycle, the daily treatment capacity of the unit is increased, thereby gradually reducing the hydraulic retention time to 12 hours. The process for each cycle is set as follows: 80 min water replenishment, 10 min anaerobic digestion, 3-10 min aeration, 50 min sedimentation, and 30 min decanting.

[0049] During the water replenishment stage, the concentration of pollutants entering the AGS device is controlled by adjusting the valve opening on the high and low concentration wastewater pipelines, with the COD value ranging from 800 to 4000 mg / L.

[0050] During the aeration stage, the aeration time is adjusted to 300-350 minutes based on the effluent COD and ammonia nitrogen concentrations. If the effluent COD and ammonia nitrogen concentrations are high, the aeration time and aeration volume should be appropriately extended.

[0051] Meanwhile, by controlling the air supply, the dissolved oxygen (DO) is kept below 0.2 mg / L in the first 60 minutes of the aeration phase, below 0.5 mg / L in the first 250 minutes of the aeration phase, and above 2 mg / L in the last 30 minutes of the aeration phase.

[0052] S5. Staged sludge discharge achieves rapid sludge screening and maintains a high sludge concentration, ensuring the average sludge particle size is greater than 0.2mm through screening. Less than 35 mL / g.

[0053] The fifth day after the device is started is the first sludge discharge stage. Sludge discharge begins within 30 minutes after sedimentation begins. The amount of sludge discharged is calculated using formula (4).

[0054] That is, starting from the 5th day after the unit starts up, the sludge discharge time is 30 minutes after the sedimentation begins, and the sludge discharge amount is given by formula (4); starting from about the 10th day after the unit starts up, the sludge discharge time is 20 minutes after the sedimentation begins, and the daily sludge discharge amount is 2% of the effective volume of the unit, that is When the sludge interface is already below the sludge discharge port after 15 minutes of settling, the sludge discharge will begin 5 minutes after the settling begins.

[0055] On the 10th day after the device is started or When the sludge concentration is less than 70 mL / g, the second sludge removal stage begins. The main purpose of this stage is sludge screening. After undergoing multiple "eutrophic-anemic" conditions, the sludge is stimulated to secrete viscous extracellular polymeric substances (EPS), which act as a "binder," allowing the dispersed flocculent sludge to self-aggregate into granular sludge. After 10 days of start-up and commissioning, tiny particles begin to appear. These particles have a higher specific gravity and faster settling velocity, and during the sedimentation stage, they account for a relatively large proportion in the lower and middle parts of the device. Therefore, the sludge removal in this stage mainly involves discharging dispersed, tiny flocculent sludge.

[0056] Sludge discharge begins 15 minutes after sedimentation begins, i.e., 15 minutes after the blower stops running. The daily sludge discharge volume is 2% of the effective volume of the unit, calculated based on a sludge age of 50 days. This continues until the sludge interface is below the discharge port 15 minutes after sedimentation begins, at which point the second sludge discharge stage ends. When the concentration is less than 50 mL / g, the settling performance of the sludge has been improved, and the sludge has gradually become granulated, entering the third stage of sludge discharge.

[0057] The third mud removal stage at this time For sludge concentrations less than 50 mL / g, the sludge discharge should begin 5 minutes after sedimentation starts. This stage primarily involves discharging flocculent sludge with poor settling properties while retaining granular sludge. The sludge discharge volume is calculated using the following formula: (4) During the third sludge discharge stage, when the sludge concentration is below 12 g / L, sludge discharge can be suspended to maintain a high sludge concentration. During the stable operation stage, sludge discharge is carried out in accordance with the method of the third sludge discharge stage.

[0058] Large granular sludge refers to sludge with a particle size greater than 0.2 mm. This reflects the settling properties of the sludge. The sludge granulation process is complete when the sludge concentration is less than 50 mL / g and the average particle size is greater than 0.2 mm. To maintain a high sludge concentration, in... When the sludge concentration is less than 50 mL / g and the average particle size is greater than 0.2 mm, sludge discharge should be suspended until the sludge concentration rises to 15-18 g / L. Within this range, the sludge settling ratio (SV) should be within 30 minutes. 30 Not exceeding 0.45 No sludge is discharged when the sludge concentration does not exceed 40 mL / g. This is to maintain a high sludge concentration within the device.

[0059] It should be noted that maintaining the high sludge concentration (MLSS at 15-18 g / L) is the key to this method.

[0060] When using aerobic biological methods to treat wastewater, the sludge load should generally not exceed 0.3 kg COD / (kg MLSS·d). The MLSS of traditional activated sludge processes is generally 3.5-4.5 g / L, making it difficult to effectively treat medium- to high-concentration wastewater within a short retention time.

[0061] While there are successful cases of using AGS technology to treat low-concentration municipal wastewater in traditional wastewater treatment, there are no reports of using AGS technology in the treatment of medium- and high-concentration wastewater.

[0062] The reason why AGS technology can treat medium- to high-concentration organic wastewater more economically and efficiently is that it forms dense granular sludge with excellent settling properties, which can maintain a high sludge concentration and increase the unit volume load of wastewater treatment facilities.

[0063] In contrast, AGS technology, due to its dense sludge structure, fast settling speed, and good sludge-water separation effect, can maintain a higher MLSS. This allows the volumetric loading of the AGS process section to reach 3-4 times that of traditional processes, thus enabling the effective treatment of medium-to-high concentration wastewater with a very short hydraulic retention time (HRT). Therefore, the AGS process is the optimal choice for treating this type of wastewater.

[0064] The beneficial effects achieved after the implementation of this patent in treating high-concentration organic wastewater are compared with the technical parameters of the aerobic section of the plant where the device is located, as shown in Table 1: Table 1 Comparison of technical parameters of the present invention and existing technologies A higher value indicates a higher treatment load per unit volume, meaning a smaller tank volume is needed to treat a specific scale of wastewater, thus saving on investment costs and floor space.

[0065] A lower HRT value indicates a smaller volume required to treat a specific scale of wastewater. Table 1 shows the differences between the present invention and existing technologies. A difference of 2-4 times in the value and a difference of 2-2.5 times in the HRT value indicates that 50%-70% of the pool volume or land area can be saved, and at least 50% of the investment and construction costs can also be saved.

[0066] The power consumption per unit COD of this invention is only 54% of that of existing technologies. Compared with existing technologies, this invention can save approximately 46% of power consumption, significantly reducing operating costs and energy input. In summary, this invention demonstrates significant beneficial effects in treating high-concentration organic wastewater.

[0067] When wastewater with COD greater than 2000 mg / L is treated as described above, with an HRT of 12-18 hours, the average removal rate of COD is greater than 97%, the average removal rate of TN is 87%, and the average removal rate of TP is 90%.

[0068] The COD of the influent to the A / O section of the plant where the AGS unit is located is about 800 mg / L, and its HRT is 30.3 h.

[0069] This invention can achieve a lower hydraulic retention time even when the influent COD value is higher, which shows that this invention breaks through the dilemma of long HRT in aerobic treatment of high COD wastewater.

[0070] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for treating medium-to-high concentration organic wastewater based on aerobic granular sludge, characterized in that, Includes the following steps: S1. During the commissioning period, gradually increase the cycle water exchange ratio to shorten the hydraulic retention time (HRT) to 12 hours. Use a fast decanting and slow replenishment method in each cycle to enhance biological phosphorus removal and avoid short-flow of effluent. S2. An operating cycle with a duration of 6-12 hours is adopted. Each operating cycle includes: water replenishment, anaerobic digestion, aeration, sedimentation, and decanting. The aeration time is more than 60% of the total operating cycle time. S3. The coupling of multiple parameters, including organic volumetric loading, sludge loading, and influent and effluent water quality, enables rapid process commissioning and sludge granulation. S4. During the aeration stage, the dissolved oxygen value is controlled by gradient. S5. Staged sludge discharge achieves rapid sludge screening and maintains a high sludge concentration, ensuring the average sludge particle size is greater than 0.2mm through screening. Less than 35 mL / g.

2. The method for treating medium-to-high concentration organic wastewater based on aerobic granular sludge according to claim 1, characterized in that: In step S1, water is decanted quickly and replenished slowly, with decanting completed within 30 minutes and replenishment completed within 80 minutes per cycle.

3. According to claim 1, a method for treating medium-to-high concentration organic wastewater based on aerobic granular sludge, in step S1, sludge is inoculated at the initial stage of AGS device startup. The amount of water replenished per cycle is determined by the sludge load and volumetric load. When the COD and total nitrogen in the decanting water quality indicators are lower than the design discharge requirements, the water exchange ratio for each operating cycle is increased by 20%-30% to increase the daily treatment capacity. The larger the daily treatment capacity, the smaller the hydraulic retention time (HRT), until the HRT is reduced to 12 hours or reaches the design treatment scale.

4. The method for treating medium-to-high concentration organic wastewater based on aerobic granular sludge according to claim 1, characterized in that: In step S2, when the hydraulic retention time is 12-18h, the duration of each cycle is adjusted according to the COD value of the wastewater. When the COD value of the wastewater is in the range of 800-1200mg / L, 1200-2000mg / L, and 2000-3000mg / L, the total duration of each cycle is 6h, 8h, and 12h, respectively. The aeration duration within each cycle is 200min, 310min, and 550min, respectively. The water replenishment duration of each cycle is 80min, the decanting duration of each cycle is 30min, the sedimentation stage duration is 30min or 40min, and the anaerobic stage duration is 10min or 20min. During the water intake phase, the wastewater to be treated is pumped into the AGS device, and water is replenished into the AGS device through a uniform water distributor. The amount of water replenished in each operating cycle is the same as the amount of water decanted, and water is decanted first and then water is replenished.

5. The method for treating medium-to-high concentration organic wastewater based on aerobic granular sludge according to claim 1, characterized in that: In step S4, the operating frequency or start / stop of the blower is controlled by the embedded control program. During the first 30% of the aeration period, the dissolved oxygen does not exceed 0.2 mg / L, during the last 15% of the aeration period, the dissolved oxygen is not lower than 2 mg / L, and during the middle stage of aeration, the dissolved oxygen is maintained between 0.5 and 1 mg / L.

6. The method for treating medium-to-high concentration organic wastewater based on aerobic granular sludge according to claim 1, characterized in that: In step S5, This reflects the settling performance of the sludge. When the average particle size of the sludge is greater than 0.2 mm, the sludge granulation process is complete. To maintain a high sludge concentration, in... Sludge discharge should be suspended when the sludge concentration is less than 50 mL / g and the average particle size is greater than 0.2 mm, until the sludge concentration rises to 15-18 g / L. Within this range, the sludge settling ratio should be within 30 minutes. Not exceeding 0.45 No sludge is discharged when the concentration is below 40 mL / g.

7. A medium-to-high concentration organic wastewater treatment system based on aerobic granular sludge, used to implement the medium-to-high concentration organic wastewater treatment method based on aerobic granular sludge as described in any one of claims 1-6, characterized in that, include: AGS unit is used to hold a mixture of sludge and wastewater. The aeration system, installed at the bottom of the AGS unit, provides aeration and mixing to the wastewater inside the AGS unit; A uniform water distributor, installed at the bottom of the AGS unit, is used to replenish wastewater into the interior of the AGS unit; The sludge discharge system, installed in the middle of the AGS unit, is used to discharge small-particle sludge. The decanter, installed in the middle of the AGS unit, is used to drain the supernatant that has been processed inside the AGS unit. The intelligent control unit includes an AGS control device and an online instrument. The intelligent control unit is also equipped with an embedded control program that controls the start and stop of the AGS control device based on the data from the online instrument. The AGS device is circular or rectangular in shape, with a total height of 7 meters and an effective water depth of 6.5 meters. The AGS control equipment includes a water pump installed on the inlet pipe, multiple electric valves installed on the decanter pipe and the sludge discharge system pipe, and a blower for aerating the wastewater. The online instruments include an online dissolved oxygen meter, an online level gauge, an online thermometer, an online ammonia nitrogen meter, and an online sludge interface meter.

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