Method for realizing stable and standard reaching of effluent by using intelligent internal reflux and realizing energy conservation and consumption reduction

Abstract

The invention discloses a method for realizing stable and up-to-standard effluent, energy conservation and consumption reduction by using intelligent internal reflux, and belongs to the technical field of sewage treatment. According to the method, the TN concentration of the inlet water of the sewage treatment plant is collected through an inlet water TN probe, the required reflux ratio is calculated according to the effluent standard, the required internal reflux ratio r is obtained by subtracting the actual external reflux ratio R from the total reflux ratio (R + r) according to the calculation result, and the calculation result is checked according to the NO3 <->-N concentration of the effluent at the tail end of the anoxic tank and the tail end of the aerobic tank. And correcting the calculated result r. When the concentration of NO3 <->-N in the effluent of the aerobic tank is higher than a theoretical value and exceeds 1mg / L, the internal reflux quantity is increased. And the internal reflux ratio is adjusted according to the corrected result, and reflux is performed as required, so that the effluent reaches the standard, the fluctuation of TN of the effluent is reduced, the reflux power consumption is reduced, and the purposes of reducing pollution and carbon are achieved.

Description

Technical Field

[0001] The invention relates to a method for achieving stable effluent compliance and energy saving and consumption reduction by utilizing intelligent internal reflux, and belongs to the technical field of sewage treatment. Background Art

[0002] Excessive nitrogen in water bodies is one of the important factors causing water pollution and eutrophication, which will destroy the ecological balance of water bodies and threaten the safety of water intake at water sources.

[0003] At present, the denitrification of sewage treatment plants is a microbial denitrification treatment method that relies on nitrifying bacteria and denitrifying bacteria. Denitrification is divided into two stages: nitrification and denitrification. Under aerobic conditions, nitrifying bacteria in sewage are used to convert nitrogen-containing substances (including organic nitrogen and ammonia nitrogen) into nitrate nitrogen. Then, under anaerobic conditions (without molecular oxygen), denitrifying bacteria in sewage are used to reduce nitrate nitrogen to gaseous nitrogen, ultimately achieving the removal of nitrogen from sewage.

[0004] The specific reaction process is as follows:

[0005] NH 4 + +2O 2 →NO 3 - +H 2 O+2H + (1)

[0006] 6H + +6NO 3 - +5CH 3 OH→3N 2 +13H 2 O+5CO 2 (2)

[0007] A 2 O process (AAO process) is the abbreviation of the first letters of Anaerobic-Anoxic-Oxic (anaerobic-anoxic-aerobic). It is a commonly used secondary sewage treatment process with the function of simultaneous nitrogen and phosphorus removal. It can be used for secondary sewage treatment or tertiary sewage treatment and has good nitrogen and phosphorus removal effects.

[0008] Denitrification in biological pools in sewage treatment plants is affected by factors such as carbon source, dissolved oxygen (DO), stirring effect, and reflux ratio. 2 In O and similar processes, the theoretical maximum efficiency of denitrification is affected by reflux, and its theoretical maximum efficiency can be expressed as:

[0009] Theoretical total nitrogen removal rate = (R+r) / (R+r+1) (3)

[0010] Wherein, R: external reflux ratio; r: internal reflux ratio.

[0011] From formula (3), it can be seen that when the TN concentration of the sewage treatment plant influent is determined and the ratio of internal reflow to external reflow is determined, its theoretical maximum denitrification efficiency is determined, that is, the minimum concentration of TN in the effluent is also determined. Therefore, by adjusting the reflow ratio of the sewage treatment plant, the theoretical denitrification efficiency of the sewage treatment plant can be adjusted to achieve the adjustment of the effluent TN concentration. Similarly, when the TN concentration of the sewage treatment plant influent and the TN standard of the effluent are known, the required theoretical reflow ratio can be calculated.

[0012] From formula (3), we can deduce A 2 The calculation formula of the reflux volume in the O process is:

[0013] r=(TN 进水 / TN 出水 )-1-R (4)

[0014] Among them, TNN 进 : TN concentration of sewage treatment plant influent; TN 出水 :Control effluent concentration within sewage treatment plants.

[0015] In A 2 In the NO and similar processes, the reflux consists of two parts: external reflux (sludge reflux) is mainly used to adjust the sludge concentration in the system, and the adjustment range is generally 50% to 100%; internal reflux (nitrification liquid reflux) is mainly used to convert the converted NO 3 - -N flows back to the anoxic pool, where it converts NO 3 - -N is converted to N 2 , to achieve the final biological denitrification, the adjustment range is generally 100% to 300%.

[0016] At present, most sewage treatment plants use fixed flow or manual adjustment for internal reflow, and the adjustment frequency is extremely low. In order to ensure that the TN concentration of the effluent is stable and meets the standard, most sewage treatment plants adjust the internal reflow ratio to a larger value, resulting in large fluctuations in the TN concentration of the effluent and high energy consumption. When the inlet TN concentration is low, the effluent TN concentration is far lower than the effluent standard, resulting in a waste of reflow power consumption, which runs counter to the goal of low-carbon operation of the sewage treatment plant. When the inlet TN concentration is high, the reflow ratio reaches the maximum value. Due to the limitation of the inlet carbon-nitrogen ratio, the denitrification of the anoxic tank is incomplete, and the effluent TN may also exceed the effluent standard.

[0017] In order to meet the high standard of TN of sewage treatment plant effluent and avoid wasting electricity, various factors affecting denitrification and denitrification need to be in the optimal conditions as much as possible. As one of the important factors affecting denitrification efficiency, the reflux of nitrification liquid directly affects the efficiency of denitrification. In order to control the reflux of nitrification liquid within the most appropriate range, it is urgent to find a method of intelligent reflux control to meet the demand of denitrification and denitrification for reflux ratio and avoid wasting electricity due to excessive reflux ratio. Summary of the invention

[0018] [Technical issues]

[0019] The internal recirculation volume in the sewage treatment plant does not match the target concentration of effluent total nitrogen (TN), resulting in large fluctuations in effluent TN and high-frequency operation of the reflux pump, which wastes electricity.

[0020] Most sewage treatment plants use fixed flow or manual regulation for internal recirculation, with an extremely low adjustment frequency, resulting in high energy consumption and unstable effluent total nitrogen (TN) concentration.

[0021] [Technical solution]

[0022] In order to solve the above problems, the present invention calculates the required total theoretical reflux ratio according to the TN (total nitrogen) concentration of the sewage treatment plant and the effluent standard using the denitrification denitrification formula, subtracts the actual external reflux ratio from the required total theoretical reflux ratio to obtain the required theoretical nitrification liquid reflux ratio, and adjusts the flow rate of the internal reflux pump according to the calculation result. In order to ensure the safety of the effluent and the accuracy of the system, the NO2 content of the effluent at the end of the anoxic tank and the end of the aerobic tank is adjusted. 3- -N concentration correction calculation results, fine-tuning the reflux ratio, solved the problem of "mismatch between internal reflux volume and effluent total nitrogen (TN) concentration, resulting in effluent water quality fluctuations and waste of electricity".

[0023] Specifically, the TN concentration of the sewage treatment plant inlet is collected through the inlet TN probe, and the required reflow ratio is calculated by referring to the effluent standard. The required internal reflow ratio r is obtained by subtracting the actual external reflow ratio R from the calculated total reflow ratio (R+r). 3 - -N concentration calibration calculation results, the calculated results r are corrected. 3 - When the -N concentration is higher than the theoretical value by more than 1 mg / L, increase the internal reflux volume. Adjust the internal reflux ratio according to the corrected results, reflux as needed, and achieve the goal of meeting the effluent standards while reducing the fluctuation of effluent TN and reflux power consumption, thereby achieving the goal of reducing pollution and carbon emissions.

[0024] The first object of the present invention is to provide an intelligent backflow control system for sewage treatment, the intelligent backflow control system includes an inlet pump room, an inlet TN probe, an inlet pump, an inlet flow meter, an anoxic tank NO 3 - -N probe, aerobic pool NO 3 - -N probe, internal reflux pump, internal reflux flowmeter, electric energy meter, secondary sedimentation tank, effluent, sewage treatment plant master control system, intelligent reflux PLC control cabinet, anaerobic tank, anoxic tank, aerobic tank;

[0025] Among them, the water inlet TN probe is installed in the water inlet pump room;

[0026] The inlet TN probe, inlet flow meter, internal reflux flow meter, internal reflux pump and electric energy meter are connected to the overall control system of the sewage treatment plant through signal lines;

[0027] Hypoxic pool NO 3 - -N probe is installed at the end of the anoxic pool;

[0028] Aerobic pool NO 3 - -N probe is installed at the end of the aerobic pool;

[0029] Hypoxic pool NO 3 - -N probe, aerobic pool NO 3 - -N probe is connected to the intelligent reflux PLC control cabinet through a signal line;

[0030] The intelligent return PLC control cabinet is connected to the overall control system of the sewage treatment plant.

[0031] In one embodiment of the present invention, the inlet TN probe collects the total nitrogen (TN) concentration data in the inlet water of the sewage treatment plant online, and then feeds it back to the main control system of the sewage treatment plant. The intelligent return PLC control cabinet reads the data from the main control system of the sewage treatment plant.

[0032] In one embodiment of the present invention, an inlet flow meter is installed in the inlet pipe of a sewage treatment plant to monitor the inlet water volume, which is then fed back to the overall control system of the sewage treatment plant. The intelligent reflux PLC control cabinet reads data from the overall control system of the sewage treatment plant.

[0033] In one embodiment of the invention, the anoxic pool NO 3 - -N probe is used to collect NO in the effluent of the anoxic pool online 3 - -N concentration, and then fed back to the intelligent reflux PLC control cabinet.

[0034] In one embodiment of the present invention, the aerobic pool NO 3 - -N probe is used to collect NO in the effluent of aerobic pool online 3 - -N concentration, and then fed back to the intelligent reflux PLC control cabinet.

[0035] In one embodiment of the present invention, the internal reflux pump receives instructions from the overall control system of the sewage treatment plant and adjusts the flow rate through a matching frequency converter according to the instructions.

[0036] In one embodiment of the present invention, an internal reflux flowmeter is installed in the internal reflux main pipe of the sewage treatment plant to monitor the internal reflux flow.

[0037] In one embodiment of the present invention, an electric energy meter is installed in the power supply circuit of the internal return pump to monitor and measure the power consumption of the internal return pump; and then the power consumption is fed back to the overall control system of the sewage treatment plant.

[0038] In one embodiment of the present invention, the operating principle of the intelligent reflux control system for sewage treatment is:

[0039] (1) The sewage treatment plant inputs sewage to the water inlet pump room, and the data read by the water inlet TN probe and the data of the water inlet flow meter are transmitted to the main control system of the sewage treatment plant;

[0040] The intelligent reflux PLC control cabinet reads the influent TN concentration from the sewage treatment plant's main control system and calculates the internal reflux ratio r using the following formula;

[0041] r=(TN 进水 / TN 出水 )-1-R

[0042] Among them, TN 进水 : TN concentration of sewage treatment plant influent; TN 出水 : Controlled effluent concentration in the sewage treatment plant; R: External reflow ratio;

[0043] (2) The sewage is transported to the anoxic tank, where NO 3 - -N probe reads data and transmits it to the intelligent reflux PLC control cabinet;

[0044] Anoxic pool effluent NO 3 - The data read by the -N probe is used to indicate the denitrification effect of the anoxic pool. 3 - -When the N concentration exceeds 2 mg / L, it is necessary to increase the amount of carbon source added to the anoxic pool to avoid incomplete denitrification in the anoxic pool affecting the effect of the intelligent reflow control system;

[0045] (3) The sewage continues to flow to the aerobic pool, where NO 3 - -N probe reads data and transmits it to the intelligent reflux PLC control cabinet;

[0046] According to the NO 3 - -N concentration corrects the internal reflow ratio r if and only if the aerobic pool effluent NO 3 - - If the N concentration exceeds the internal control index by more than 1 mg / L, add 25% of the internal reflux volume to the calculated result to obtain the corrected internal reflux volume r';

[0047] According to the actual water inlet flow Q, calculate the required internal return flow Q 内回流 =Q×r', the calculated result Q 内回流 The command is transmitted to the internal return pump through the main control system of the sewage treatment plant, and the internal return pump executes the command;

[0048] The internal recirculation flow meter is used to monitor the deviation between the actual flow and the theoretical flow, and the electric energy meter is used to monitor the energy consumption of the internal recirculation and transmit the monitoring results to the overall control system of the sewage treatment plant.

[0049] The second object of the present invention is to provide a method for achieving stable TN compliance of effluent water and energy saving and consumption reduction by utilizing intelligent internal reflux, wherein the method adopts an intelligent reflux control system for sewage treatment.

[0050] In one embodiment of the present invention, the method comprises the following:

[0051] (1) The sewage treatment plant inputs sewage to the water inlet pump room, and the data read by the water inlet TN probe and the data of the water inlet flow meter are transmitted to the main control system of the sewage treatment plant;

[0052] The intelligent reflow PLC control cabinet reads the influent TN concentration from the sewage treatment plant's main control system and calculates the internal reflow ratio r using the following formula;

[0053] r=(TN 进水 / TN 出水 )-1-R

[0054] Among them, TN 进水 : TN concentration of sewage treatment plant influent; TN 出水 : Controlled effluent concentration in the sewage treatment plant; R: External reflow ratio R;

[0055] (2) The sewage is transported to the anoxic tank, where NO 3 - -N probe reads data and transmits it to the intelligent reflux PLC control cabinet;

[0056] According to the NO3 - -N concentration corrects the internal reflow ratio r if and only if the aerobic pool effluent NO 3 - - If the N concentration exceeds the internal control index by more than 1 mg / L, add 25% of the internal reflux volume to the calculated result to obtain the corrected internal reflux volume r';

[0057] According to the actual water inlet flow Q, calculate the required internal return flow Q 内回流 =Q×r', the calculated result Q 内回流 The command is transmitted to the internal return pump through the main control system of the sewage treatment plant, and the internal return pump executes the command;

[0058] The internal recirculation flow meter is used to monitor the deviation between the actual flow and the theoretical flow, and the electric energy meter is used to monitor the energy consumption of the internal recirculation and transmit the monitoring results to the overall control system of the sewage treatment plant;

[0059] (3) The sewage continues to flow to the aerobic pool, where NO 3 - -N probe reads data and transmits it to the intelligent reflux PLC control cabinet;

[0060] Anoxic pool effluent NO 3 - The data read by the -N probe is used to indicate the denitrification effect of the anoxic pool. 3 - When the -N concentration exceeds 2 mg / L, it is necessary to increase the amount of carbon source added to the anoxic tank to avoid incomplete denitrification in the anoxic tank affecting the effect of the intelligent reflow control system.

[0061] The third object of the present invention is to apply the intelligent reflux control system for sewage treatment and the method for intelligent regulation of reflux in a sewage treatment plant described in the present invention to the field of sewage treatment.

[0062] [Beneficial Effects]

[0063] (1) The present invention uses an internal reflow intelligent control method to adjust the internal reflow rate of a sewage treatment plant. According to the influent TN concentration and effluent standard of the sewage treatment plant, the required total reflow ratio is calculated using the denitrification formula. The required internal reflow is obtained by subtracting the external reflow ratio from the total reflow ratio. The internal reflow is then adjusted according to the effluent NO of the anoxic tank and the aerobic tank. 3 - -N concentration correction calculates the internal reflow r, and adjusts the internal reflow ratio according to the corrected result. Realizing on-demand reflow can avoid excessive TN in the effluent due to insufficient reflow, and avoid excessive reflow, which causes waste of electricity. Through the intelligent control method of internal reflow, while ensuring the stable compliance of TN in the effluent, it saves reflow power consumption and achieves the goal of reducing pollution and carbon emissions in the sewage treatment plant.

[0064] (2) The internal reflow intelligent control method of the present invention can ensure that the TN concentration of the effluent meets the discharge standards and effectively reduce the fluctuation of the TN concentration of the effluent. Through adjustment, the TN concentration of the effluent is stably controlled between 6-9 mg / L.

[0065] (3) The present invention can reduce the power consumption of internal reflux through intelligent reflux regulation. The reflux power consumption after using the system can be reduced by 20%-30% compared with before use, and the TN level of the outlet water is more stable.

[0066] (4) The internal reflow intelligent control method of the present invention can calculate the required reflow volume by testing the water quality and the effluent standard, and then achieve the stable compliance of the effluent water quality and the optimal ratio of the reflow volume by adjusting the reflow volume, thereby achieving the dual goals of meeting the water quality standards and energy saving and consumption reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 This is a schematic diagram of the intelligent return flow control system for sewage treatment; 1. Inlet pump room, 2. Inlet TN probe, 3. Inlet pump, 4. Inlet flow meter, 5. Anoxic tank NO 3 - -N probe, 6, aerobic pool NO 3 - -N probe, 7. internal reflux pump, 8. internal reflux flowmeter, 9. electric energy meter, 10. secondary sedimentation tank, 11. effluent, 12. sewage treatment plant master control system, 13. intelligent reflux PLC control cabinet, 14. anaerobic tank, 15. anoxic tank, 16. aerobic tank.

[0068] Figure 2 Schematic diagram of data transmission in the intelligent return flow control system of sewage treatment.

[0069] Figure 3 This is a test result chart of the TN concentration of the inlet and outlet water and the energy consumption of the reflux pump of the sewage treatment plant within 30 days using the intelligent reflux control system for sewage treatment of Example 1 in Example 1.

[0070] Figure 4 This is a test result chart of the TN concentration of the inlet and outlet water and the energy consumption of the reflux pump of the sewage treatment plant within 30 days in Comparative Example 1, which does not use the intelligent reflux control system for sewage treatment of Example 1.

[0071] Figure 5 This is the test result chart of TN concentration of influent and effluent water and energy consumption of return pump of sewage treatment plant within 30 days in comparative example 2. DETAILED DESCRIPTION

[0072] The preferred embodiments of the present invention are described below. It should be understood that the embodiments are for better explaining the present invention and are not used to limit the present invention.

[0073] Example 1

[0074] An intelligent backflow control system for sewage treatment, such as Figure 1 , including water inlet pump room 1, water inlet TN probe 2, water inlet pump 3, water inlet flow meter 4, anoxic pool NO 3 - -N probe 5, aerobic pool NO 3 - -N probe 6, internal reflux pump 7, internal reflux flowmeter 8, electric energy meter 9, secondary sedimentation tank 10, effluent 11, sewage treatment plant total control system 12, intelligent reflux PLC control cabinet 13, anaerobic tank 14, anoxic tank 15, aerobic tank 16;

[0075] Among them, the water inlet TN probe 2 is installed in the water inlet pump room;

[0076] The inlet TN probe 2, the inlet flow meter 4, the internal reflux flow meter 8, the internal reflux pump 7, and the electric energy meter 9 are connected to the sewage treatment plant general control system 12 through signal lines;

[0077] Hypoxic pool NO 3 - -N probe 5, aerobic pool NO 3 - -N probes 6 are installed at the ends of the anoxic pool and the aerobic pool respectively, and are connected to the intelligent reflux PLC control cabinet 13 through signal lines;

[0078] The intelligent return PLC control cabinet 13 is connected to the sewage treatment plant master control system 12;

[0079] The inlet TN probe 2 collects the total nitrogen concentration data of the inlet water of the sewage treatment plant online, and then feeds it back to the sewage treatment plant master control system 12. The intelligent return PLC control cabinet 13 reads the data from the sewage treatment plant master control system 12;

[0080] The inlet flow meter 4 is installed on the inlet pipe of the sewage treatment plant to monitor the inlet water volume, which is then fed back to the sewage treatment plant master control system 12. The intelligent return PLC control cabinet 13 reads data from the sewage treatment plant master control system 12;

[0081] Hypoxic pool NO 3 - -N probe 5 is used to collect NO in the effluent of the anoxic pool online 3 - -N concentration, which is then fed back to the intelligent reflux PLC control cabinet 13;

[0082] Aerobic pool NO 3 - -N probe 6 is used to collect NO in the effluent of the aerobic pool online 3 - -N concentration, which is then fed back to the intelligent reflux PLC control cabinet 13;

[0083] The internal reflux pump 7 receives instructions from the sewage treatment plant's general control system 12 and adjusts the flow rate through a matching frequency converter according to the instructions;

[0084] The internal reflux flow meter 8 is installed in the reflux main pipe of the sewage treatment plant to monitor the internal reflux flow;

[0085] The electric energy meter 9 is installed in the power supply circuit of the internal return pump 7 to monitor and measure the power consumption of the internal return pump; and then feeds back to the main control system 12 of the sewage treatment plant.

[0086] The operating principle of the intelligent return flow control system for sewage treatment is:

[0087] (1) The sewage treatment plant inputs sewage to the water inlet pump room 1, and the data read by the water inlet TN probe 2 and the data of the water inlet flow meter 4 are transmitted to the sewage treatment plant general control system 12;

[0088] The intelligent reflux PLC control cabinet 13 reads the influent TN concentration from the sewage treatment plant master control system 12 and calculates the internal reflux ratio r using the following formula;

[0089] r=(TN 进水 / TN 出水 )-1-R

[0090] Among them, TN 进水 : TN concentration of sewage treatment plant influent; TN 出水 : Controlled effluent concentration in the sewage treatment plant; R: External reflow ratio R;

[0091] (2) The sewage is transported to the anoxic tank 15, and the anoxic tank NO 3 - -N probe 5 reads the data and transmits it to the intelligent reflux PLC control cabinet 13;

[0092] Anoxic pool effluent NO 3 - -The data read by N probe 6 is used to indicate the denitrification effect of anoxic pool 5. 3 - -When the N concentration exceeds 2 mg / L, it is necessary to increase the amount of carbon source added to the anoxic pool to avoid incomplete denitrification in the anoxic pool affecting the effect of the intelligent reflow control system;

[0093] (3) The sewage continues to flow to the aerobic tank 16. The aerobic tank NO 3 - -N probe 6 reads the data and transmits it to the intelligent reflux PLC control cabinet 13;

[0094] According to the NO 3 --N concentration corrects the internal reflow ratio r if and only if the aerobic pool effluent NO 3 - - If the N concentration exceeds the internal control index by more than 1 mg / L, add 25% of the internal reflux volume to the calculated result to obtain the corrected internal reflux volume r';

[0095] According to the actual water inlet flow Q, calculate the required internal return flow Q 内回流 =Q×r', the calculated result Q 内回流 The command is transmitted to the internal return pump 7 through the sewage treatment plant master control system 12, and the internal return pump 7 executes the command;

[0096] The internal reflux flow meter 8 is used to monitor the deviation between the actual flow and the theoretical flow;

[0097] The electric energy meter 9 is used to monitor the energy consumption of the internal recirculation and transmit the monitoring result to the overall control system 12 of the sewage treatment plant.

[0098] Example 2

[0099] A method for achieving stable effluent compliance and energy saving and consumption reduction by using intelligent internal recirculation, wherein the method adopts the intelligent internal recirculation control system for sewage treatment of Example 1;

[0100] The processing objects and processes are:

[0101] A sewage treatment plant with an influent capacity of 20,000 tons / day and a biological treatment process of A 2 O process;

[0102] The TN standard of the plant’s effluent is 10mg / L, and the internal control index is 8mg / L;

[0103] The processing device is:

[0104] A 2 The O pool (anaerobic pool, aerobic pool, anoxic pool) is divided into 2 groups, equipped with 6 internal return pumps, 4 in use and 2 in standby, with a single internal return pump flow of 840m 3 / h, power 15kW;

[0105] according to Figure 1 All the supporting equipment and facilities such as probes and electric energy meters are equipped as shown;

[0106] The specific method is as follows:

[0107] (1) The sewage treatment plant inputs sewage to the water inlet pump room 1, and the data read by the water inlet TN probe 2 and the data of the water inlet flow meter 4 are transmitted to the sewage treatment plant general control system 12;

[0108] The intelligent reflux PLC control cabinet 13 reads the influent TN concentration from the sewage treatment plant master control system 12 and calculates the internal reflux ratio r using the following formula;

[0109] r=(TN 进水 / TN 出水 )-1-R

[0110] Among them, TN 进水 : TN concentration of sewage treatment plant influent; TN 出水 : Controlled effluent concentration in the sewage treatment plant; R: External reflow ratio R;

[0111] (2) The sewage is transported to the anoxic tank 15, and the anoxic tank NO 3 - -N probe 5 reads the data and transmits it to the intelligent reflux PLC control cabinet 13;

[0112] Anoxic pool effluent NO 3 - -N probe 6 reads the data used to indicate the denitrification effect of anoxic pool 5. 3 - -When the N concentration exceeds 2 mg / L, it is necessary to increase the amount of carbon source added to the anoxic pool to avoid incomplete denitrification in the anoxic pool affecting the effect of the intelligent reflow control system;

[0113] (3) The sewage continues to flow to the aerobic tank 16. The aerobic tank NO 3 - -N probe 6 reads the data and transmits it to the intelligent reflux PLC control cabinet 13;

[0114] According to the NO 3 - -N concentration corrects the internal reflow ratio r if and only if the aerobic pool effluent NO 3 - - If the N concentration exceeds the internal control index by more than 1 mg / L, add 25% of the internal reflux volume to the calculated result to obtain the corrected internal reflux volume r';

[0115] According to the actual water inlet flow Q, calculate the required internal return flow Q 内回流 =Q×r', the calculated result Q 内回流 The command is transmitted to the internal return pump 7 through the sewage treatment plant master control system 12, and the internal return pump 7 executes the command;

[0116] The internal reflux flow meter 8 is used to monitor the deviation between the actual flow and the theoretical flow;

[0117] The electric energy meter 9 is used to monitor the energy consumption of the internal recirculation and transmit the monitoring result to the overall control system 12 of the sewage treatment plant.

[0118] The TN concentration of the inlet and outlet water and the energy consumption of the reflux pump of the sewage treatment plant were measured within 30 days using the intelligent reflux control system of Example 1. Figure 3 shown.

[0119] Depend on Figure 3 It can be seen that after using the internal reflow intelligent control system, the sewage treatment plant's influent TN range is 15.1-48.2 mg / L, and the average influent TN concentration is 36.6 mg / L; the effluent TN concentration range is 6.5 mg / L-8.8 mg / L, and the average effluent TN concentration is 7.49 mg / L; the internal reflow power consumption range is 529-1398 kW·h / d, and the average internal reflow power consumption is 942.6 kW·h / d. The average water inflow within 30 days is 17,193 tons / day, and the internal reflow power consumption per ton of water is 0.055 kW·h.

[0120] Comparative Example 1

[0121] A method for intelligently controlling backflow in a sewage treatment plant, wherein the treatment object and process in the method are:

[0122] A sewage treatment plant with an influent capacity of 20,000 tons / day and a biological treatment process of A 2 O process;

[0123] The TN standard of the plant’s effluent is 10mg / L, and the internal control index is 8mg / L;

[0124] The processing device is:

[0125] A 2 The O pool (anaerobic pool, aerobic pool, anoxic pool) is divided into 2 groups, equipped with 6 internal return pumps, 4 in use and 2 in standby, with a single internal return pump flow of 840m 3 / h, power 15kW;

[0126] according to Figure 1 All the supporting equipment and facilities such as probes and electric energy meters are equipped as shown;

[0127] The internal and external reflow flow rates of the sewage treatment plant are fixed. The external reflow ratio is adjusted to 100%, and the internal reflow ratio is adjusted to 350%. The internal and external reflow flow rate ratio is not adjusted during use.

[0128] In the 30 days when the intelligent return flow control system was not used, the TN concentration of the inlet and outlet water and the energy consumption of the return flow pump of the sewage treatment plant were Figure 4 As shown;

[0129] Depend on Figure 4It can be seen that during this period, the TN concentration of the sewage treatment plant's influent ranged from 15.7 mg / L to 45.1 mg / L, and the average influent TN concentration was 32.19 mg / L; the effluent TN concentration ranged from 2.4 mg / L to 9.1 mg / L, and the average effluent TN concentration was 5.73 mg / L; the internal recirculation power consumption ranged from 1104 to 1321 kW·h / d, and the average internal recirculation power consumption was 1221 kW·h / d. The average influent volume for 30 days was 16631 tons / day, and the internal recirculation power consumption per ton of water was 0.072 kW·h.

[0130] contrast Figure 3 and Figure 4 It can be seen that:

[0131] (1) After using the intelligent reflux control system for sewage treatment of Example 1, the TN concentration of the effluent fluctuates slightly, while the TN concentration of the effluent fluctuates greatly before use, and there is a 60% probability that the TN concentration of the effluent is lower than 6 mg / L. This can be avoided by reducing the internal reflux ratio. That is, by appropriately reducing the internal reflux rate, the reflux power consumption can be reduced while the effluent meets the standards.

[0132] (2) After using the intelligent reflux control system for sewage treatment of Example 1, the fluctuation of TN concentration in the effluent water became smaller, and the average TN concentration in the effluent water was 7.49 mg / L, slightly lower than the internal control effluent concentration set by the system; the average daily internal reflux power consumption was reduced by 278.4 kW·h, which was 22.8% lower than that before the system was used; the internal reflux power consumption per ton of water was reduced by 0.017 kW·h, which was 23.6% lower than that before the system was used;

[0133] It can be seen that the use of the intelligent backflow control system for sewage treatment in Example 1 has achieved A 2 The effluent TN of the O process sewage treatment plant is stable and meets the standards, and the effluent TN fluctuates slightly. At the same time, it saves internal reflux power consumption and achieves the dual goals of reducing pollution and carbon emissions.

[0134] Comparative Example 2

[0135] A method for intelligently controlling backflow in a sewage treatment plant, wherein the treatment object and process in the method are:

[0136] A sewage treatment plant with an influent capacity of 20,000 tons / day and a biological treatment process of A 2 O process;

[0137] The TN standard of the plant’s effluent is 10mg / L, and the internal control index is 8mg / L;

[0138] The processing device is:

[0139] A 2The O pool (anaerobic pool, aerobic pool, anoxic pool) is divided into 2 groups, equipped with 6 internal return pumps, 4 in use and 2 in standby, with a single internal return pump flow of 840m 3 / h, power 15kW;

[0140] according to Figure 1 As shown, the oxygen removal pool NO 3 - -All probes, energy meters and other supporting equipment and facilities of N probe 5;

[0141] (1) The sewage treatment plant inputs sewage to the water inlet pump room 1, and the data read by the water inlet TN probe 2 and the data of the water inlet flow meter 4 are transmitted to the sewage treatment plant general control system 12;

[0142] The intelligent reflux PLC control cabinet 13 reads the influent TN concentration from the sewage treatment plant master control system 12 and calculates the internal reflux ratio r using the following formula;

[0143] r=(TN 进水 / TN 出水 )-1-R

[0144] Among them, TN 进水 : TN concentration of sewage treatment plant influent; TN 出水 : Controlled effluent concentration in the sewage treatment plant; R: External reflow ratio R;

[0145] (2) The sewage continues to flow to the aerobic tank 16. The aerobic tank NO 3 - -N probe 6 reads the data and transmits it to the intelligent reflux PLC control cabinet 13;

[0146] According to the NO 3 - -N concentration corrects the internal reflow ratio r if and only if the aerobic pool effluent NO 3 - - If the N concentration exceeds the internal control index by more than 1 mg / L, add 25% of the internal reflux volume to the calculated result to obtain the corrected internal reflux volume r';

[0147] According to the actual water inlet flow Q, calculate the required internal return flow Q 内回流 =Q×r', the calculated result Q 内回流 The command is transmitted to the internal return pump 7 through the sewage treatment plant master control system 12, and the internal return pump 7 executes the command;

[0148] Within 30 days of using the system, the TN concentration of the sewage treatment plant's inlet and outlet water and the energy consumption of the return pump were as follows: Figure 5 shown.

[0149] Depend on Figure 5It can be seen that after using the internal reflow intelligent control system, the sewage treatment plant's influent TN range is 13.8-46.3 mg / L, and the average influent TN concentration is 33.8 mg / L; the effluent TN concentration range is 6.1 mg / L-11.2 mg / L, and the average effluent TN concentration is 7.8 mg / L; the internal reflow power consumption range is 561-1287 kW·h / d, and the average internal reflow power consumption is 949.1 kW·h / d. The average water inflow within 30 days is 18037 tons / day, and the internal reflow power consumption per ton of water is 0.053 kW·h.

[0150] Compared with Example 2, the TN fluctuation of the effluent of Comparative Example 2 is greater than that of Example 2, and there is an over-standard situation, and the power consumption is basically the same as that of Example 2. The reason for this is that the insufficient carbon source in the influent leads to incomplete denitrification in the anoxic tank, and the NO returned to the anoxic tank 3 - -N was not fully degraded, resulting in the effluent TN failing to meet the standard stably.

[0151] Therefore, the present invention increases the NO pool by increasing the anoxic 3 - -N probe 5, used to monitor the denitrification effect of the anoxic pool. When the effluent of the anoxic pool is NO 3 - When the -N concentration is greater than 2 mg / L, it is judged that the carbon source in the influent is insufficient, and a carbon source is added to the anoxic tank to improve the denitrification and denitrification capacity of the anoxic tank.

[0152] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. An intelligent reflux control system for sewage treatment, characterized in that: The intelligent reflux control system includes an inlet pump room, an inlet TN probe, an inlet pump, an inlet flow meter, an anoxic pool NO3 - -N probe, aerobic pool NO3 - -N probe, internal reflux pump, internal reflux flowmeter, electric energy meter, secondary sedimentation tank, effluent, sewage treatment plant master control system, intelligent reflux PLC control cabinet, anaerobic tank, anoxic tank, aerobic tank; Among them, the water inlet TN probe is installed in the water inlet pump room; The inlet TN probe, inlet flow meter, internal reflux flow meter, internal reflux pump and electric energy meter are connected to the overall control system of the sewage treatment plant through signal lines; Anoxic pool NO3 - -N probe is installed at the end of the anoxic pool; Aerobic pool NO3 - -N probe is installed at the end of the aerobic pool; Anoxic pool NO3 - -N probe, aerobic pool NO3 - -N probe is connected to the intelligent reflux PLC control cabinet through a signal line; The intelligent return PLC control cabinet is connected to the overall control system of the sewage treatment plant.

2. The intelligent reflux control system according to claim 1, characterized in that: The inlet TN probe collects the total nitrogen (TN) concentration data in the inlet water of the sewage treatment plant online, and then feeds it back to the main control system of the sewage treatment plant. The intelligent return PLC control cabinet reads the data from the main control system of the sewage treatment plant.

3. The intelligent reflux control system according to claim 1, characterized in that: The inlet flow meter is installed on the inlet pipe of the sewage treatment plant to monitor the inlet water volume, which is then fed back to the main control system of the sewage treatment plant. The intelligent reflux PLC control cabinet reads data from the main control system of the sewage treatment plant.

4. The intelligent reflux control system according to claim 1, characterized in that: Anoxic pool NO3 - -N probe is used to collect NO3 in the effluent of the anoxic pool online - -N concentration, and then fed back to the intelligent reflux PLC control cabinet.

5. The intelligent reflux control system according to claim 1, characterized in that: Aerobic pool NO3 - -N probe is used to collect NO3 in the effluent of aerobic pool online - -N concentration, and then fed back to the intelligent reflux PLC control cabinet.

6. The intelligent reflux control system according to claim 1, characterized in that: The internal reflux pump receives instructions from the sewage treatment plant's overall control system and adjusts the flow rate through the matching frequency converter according to the instructions.

7. The intelligent reflux control system according to claim 1, characterized in that: The internal reflux flowmeter is installed in the reflux main pipe of the sewage treatment plant to monitor the internal reflux flow.

8. A method for achieving stable TN of outlet water and energy saving and consumption reduction by using intelligent internal reflux, characterized in that: The method described adopts the intelligent reflux control system described in any one of claims 1-7.

9. The method according to claim 8, characterized in that The methods described include the following: (1) The sewage treatment plant inputs sewage to the water inlet pump room, and the data read by the water inlet TN probe and the data of the water inlet flow meter are transmitted to the main control system of the sewage treatment plant; The intelligent reflux PLC control cabinet reads the influent TN concentration from the sewage treatment plant's main control system and calculates the internal reflux ratio r using the following formula; r=(TN 进水 / TN 出水 )-1-R Among them, TN 进水 : TN concentration of sewage treatment plant influent; TN 出水 : Controlled effluent concentration in the sewage treatment plant; R: External reflow ratio R; (2) The sewage is transported to the anoxic tank, where NO3 - -N probe reads data and transmits it to the intelligent reflux PLC control cabinet; Anoxic pool effluent NO3 - -N probe reads the data used to indicate the denitrification effect of the anoxic pool. When the anoxic pool effluent NO3 - -When the N concentration exceeds 2 mg / L, it is necessary to increase the amount of carbon source added to the anoxic pool to avoid incomplete denitrification in the anoxic pool affecting the effect of the intelligent reflow control system; (3) The sewage continues to flow to the aerobic pool, where NO3 - -N probe reads data and transmits it to the intelligent reflux PLC control cabinet; According to the NO3 in the aerobic pool - -N concentration corrects the internal reflow ratio r if and only if the aerobic pool effluent NO3 - - If the N concentration exceeds the internal control index by more than 1 mg / L, add 25% of the internal reflux volume to the calculated result to obtain the corrected internal reflux volume r'; According to the actual water inlet flow Q, calculate the required internal return flow Q 内回流 =Q×r', the calculated result Q 内回流 The command is transmitted to the internal return pump through the main control system of the sewage treatment plant, and the internal return pump executes the command; The internal recirculation flow meter is used to monitor the deviation between the actual flow and the theoretical flow, and the electric energy meter is used to monitor the energy consumption of the internal recirculation and transmit the monitoring results to the overall control system of the sewage treatment plant.

10. Application of the intelligent reflux control system according to any one of claims 1 to 7 and the method according to claim 8 or 9 in the field of sewage treatment.

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