Intelligent dosing method for nitrogen and phosphorus removal of sewage

Abstract

The invention discloses an intelligent dosing method for nitrogen and phosphorus removal of sewage, and belongs to the field of energy conservation and carbon reduction and the technical field of sewage treatment. According to the method, according to ORP of inlet and outlet water and NO3 <-> concentration of the inlet water in an anoxic tank, N dosing intervals are calculated and set by using a formula, each dosing interval corresponds to different dosing concentrations, then the dosing amount is calculated according to the water quantity of raw water, the whole process does not need personnel participation, and only the quality of the raw water needs to be monitored in real time, so that the operation is simple, and the operation is convenient. After the water quality changes, the dosage can be automatically adjusted, so that the accurate, rapid, simple and convenient determination of the carbon source dosage is realized, the water treatment effect is improved, the water treatment cost is reduced, the labor intensity of operators is reduced, and the purposes of reducing cost, improving efficiency, saving energy and reducing carbon are achieved.

Description

Technical Field

[0001] The invention relates to an intelligent dosing method for denitrification and dephosphorization of sewage, and belongs to the technical field of energy conservation, carbon reduction and sewage treatment. Background Art

[0002] The removal of nitrogen and phosphorus involves multiple biochemical processes such as nitrification, denitrification, and phosphorus release and release. Each process has different purposes and different requirements for microbial composition, substrate type, and environmental conditions. Therefore, in order to complete the denitrification and phosphorus removal processes in one system at the same time, it is inevitable that there will be contradictions between the processes, such as carbon source, sludge age, nitrate, nitrification and denitrification capacity, phosphorus release and absorption capacity, etc. Among them, denitrifying bacteria and polyphosphate bacteria play two independent roles in the denitrification and phosphorus removal processes, that is, both need to use organic carbon sources for independent denitrification and phosphorus absorption and release. Therefore, in the same system, it is inevitable that there will be competition for carbon sources.

[0003] At present, there are three main ways to add carbon sources to urban sewage treatment plants, namely constant addition, manual adjustment, and automatic addition. Among them, constant addition is added to the effluent total nitrogen TN (including NO3 - , NH3) do not exceed the standard, the carbon source dosage is basically not adjusted, and the dosage is large; manual adjustment is generally based on the effluent total nitrogen TN meter to adjust the dosage, which has a large lag, often overdosing or underdosing, and the effluent total nitrogen TN is unstable, often facing the risk of exceeding the standard; automatic addition is generally based on timing control, advanced algorithms, etc. to build predictive addition, but timing control has a large lag, and the existing advanced algorithms still rely on the effluent TN concentration for automatic addition, and the dosage is large.

[0004] Therefore, it is necessary to develop an intelligent dosing method that is easy to control and implement, can improve the stability of effluent, reduce dosing costs, and improve the refinement of operation management. Summary of the invention

[0005] [Technical issues]

[0006] The amount of carbon source added in sewage treatment plants is unstable and has a large hysteresis, resulting in a large amount of carbon source waste and increased carbon emissions.

[0007] [Technical solution]

[0008] The invention is based on the oxidation-reduction potential (ORP) of the inlet and outlet water in the anoxic pool, the NO3 - Concentration is calculated using the formula, N dosing intervals are set, each dosing interval corresponds to a different dosing concentration, and then the dosing amount is calculated based on the amount of raw water.

[0009] In order to ensure the stability of the dosage, the number of dosing intervals can be set by yourself. The more the number, the more accurate the dosing.

[0010] The present invention solves the problem that "the amount of carbon source added in a sewage treatment plant is unstable and has a large hysteresis, resulting in a large amount of carbon source waste and increased carbon emissions".

[0011] Specifically, first, N dosing intervals are set according to the redox potential difference ΔORP (-300mV~0mV) between the inlet and outlet water of the anoxic pool, and then NO3 - The concentration meter and the ORP meter of the inlet and outlet water collect data. The ORP of the inlet water of the anoxic pool minus the ORP of the outlet water of the anoxic pool is used to obtain ΔORP. The average dosing concentration corresponding to each dosing interval is calculated according to the following formula (5). - The concentration is compared with the reference value (8 mg / L), and then combined with the raw water volume, the carbon source dosage is calculated according to formula (6). After the dosage is determined, the dosing pump can be turned on to add the drug, and the PID is automatically adjusted according to the dosing flow collected by the dosing flow meter to ensure accurate dosage.

[0012] The purpose of the present invention is to provide an intelligent dosing method for sewage denitrification and phosphorus removal, which is applied to an intelligent control system for sewage denitrification and phosphorus removal, and comprises the following steps:

[0013] Step 1: According to the redox potential difference ΔORP (-300mV~0mV) between the inlet and outlet of the anoxic pool, N dosing intervals are set by yourself, and each dosing interval corresponds to a different dosing concentration;

[0014] Step 2: Install ORP online meters at the inlet and outlet of the anoxic pool, and install NO3 - For online instrumentation, the carbon source dosing point is set in the anaerobic tank;

[0015] Step 3: Obtain NO3 of the current anoxic pool inlet water - Concentration, calculate the average dosing concentration in each dosing interval according to formula (1);

[0016]

[0017] in:

[0018] [COD]: average dosing concentration, mg / L (measured in COD concentration);

[0019] [NO3 - ]: Aerobic pool effluent NO3 - Concentration, mg / L (in N);

[0020] ΔORP:ORP 缺氧池进水 -ORP 缺氧池出水 , the range is -300mV~0mV.

[0021] Obtain the ORP of the current anoxic pool inlet and outlet water to determine the specific dosing concentration.

[0022] Step 4: Combined with the current raw water flow rate, calculate the carbon source dosage according to formula (2):

[0023]

[0024] in:

[0025] M: Carbon source dosage, kg / h;

[0026] n: compensation coefficient, NO3 - When the concentration is ≤8mg / L, n is 1, NO3 - When the concentration is > 8 mg / L, n takes the value of 2;

[0027] [COD]: average dosing concentration, mg / L (measured in COD concentration);

[0028] Q: flow rate of raw water, m 3 / h;

[0029] a: COD equivalent value, dimensionless.

[0030] Step 5: After determining the dosage, you can turn on the dosing pump to add medicine, and perform PID automatic adjustment according to the dosing flow collected by the dosing flow meter to ensure accurate dosing of the medicine;

[0031] Step 6: The intelligent dosing method for wastewater nitrogen and phosphorus removal also includes: collecting the ORP of the anoxic pool inlet and outlet water and the NO3 inlet water of the anoxic pool at each dosing. - concentration, and establish a training set, use the training set for machine learning, adjust the constants in formula (1), and then calculate the carbon source dosage based on the adjusted formula.

[0032] [Beneficial Effects]

[0033] Due to the adoption of the above-mentioned technical scheme, the present invention has the following advantages and positive effects compared with the prior art: the present invention sets a plurality of dosing intervals, each dosing interval is set with a corresponding dosing concentration, and the dosing amount is determined in combination with the water volume, and the whole process does not require human participation. It only requires real-time monitoring of the raw water quality and water volume. The dosing amount can be automatically adjusted after the water quality changes, thereby realizing accurate, fast and simple determination of the carbon source dosage, improving the effect of water treatment, reducing the cost of water treatment, and reducing the labor intensity of operators, thereby achieving the purpose of reducing costs, increasing efficiency, saving energy and reducing carbon emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1The present invention is a flow chart of an intelligent dosing method for denitrification and dephosphorization of sewage.

[0035] Figure 2 Schematic diagram of the intelligent dosing system for wastewater nitrogen and phosphorus removal of the present invention; wherein, 1. carbon source dissolving device; 2. carbon source dosing pump; 3. carbon source dosing flowmeter; 4. anaerobic tank; 5. anoxic tank; 6. aerobic tank; 7. mixed liquid reflux pump; 8. mixed liquid reflux flowmeter; 9. anoxic tank inlet ORP meter; 10. anoxic tank inlet NO3 - Instrument; 11. ORP meter for effluent from anoxic tank; 12. Intelligent dosing system; 13. PLC control cabinet for carbon source addition; 14. Influent from denitrification and phosphorus removal reaction tank; 15. Effluent from denitrification and phosphorus removal reaction tank.

[0036] Figure 3 This is the average dosage distribution diagram for sewage denitrification and phosphorus removal according to the present invention.

[0037] Figure 4A This is a diagram showing the effect of carbon source dosage in a sewage treatment plant that uses manual dosing.

[0038] Figure 4B This is a diagram showing the effect of carbon source dosage in a sewage treatment plant that uses the method of this application for dosing. DETAILED DESCRIPTION

[0039] 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.

[0040] Example 1

[0041] This embodiment provides an intelligent dosing method for wastewater denitrification and phosphorus removal, which is applied to wastewater denitrification and phosphorus removal systems. Figure 2 As shown, the sewage denitrification and phosphorus removal system includes a carbon source dissolving device 1, a denitrification and phosphorus removal reaction tank, a carbon source dosing PLC control cabinet and an intelligent dosing system 12; the carbon source dissolving device 1 is used to fully dissolve the added carbon source, and the intelligent dosing system 12 is used to determine a certain dosing strategy according to relevant indicators in the denitrification and phosphorus removal reaction tank, and then feed back to the carbon source dosing PLC control cabinet, so that the carbon source dosing PLC control cabinet can add the fully dissolved carbon source in the carbon source dissolving device 1 to the denitrification and phosphorus removal reaction tank according to the dosing strategy.

[0042] like Figure 2As shown, the denitrification and dephosphorization reaction pool is provided with an anaerobic pool 4, an anoxic pool 5 and an aerobic pool 6 connected in sequence; a carbon source dosing pump 2 and a carbon source dosing flowmeter 3 are provided between the carbon source dissolving device 1 and the anaerobic pool 4, and the carbon source dosing PLC control cabinet controls the carbon source dosing amount through the carbon source dosing flowmeter 3. In the denitrification and dephosphorization reaction pool, ORP meters are provided at the water inlet and outlet of the anoxic pool 5, which are respectively denoted as the anoxic pool inlet ORP meter 9 and the anoxic pool outlet ORP meter 11. At the same time, a NO3 - Instrument, record as anoxic pool inlet water NO3 - Instrument 10; ORP instrument 9 for inlet water of anoxic pool, NO3 for inlet water of anoxic pool - The meter 10 and the anoxic pool outlet water ORP meter 11 are connected to the intelligent dosing system 12 so as to obtain the anoxic pool inlet water ORP value, anoxic pool inlet water NO3 - The ORP value of the anoxic pool outlet water is fed back to the intelligent dosing system 12. The intelligent dosing system 12 is fed back to the intelligent dosing system 12 according to the ORP value of the anoxic pool inlet and outlet water and the inlet NO3 - The value determines the amount of carbon source added.

[0043] In this embodiment, acetic acid (COD equivalent a is 1.07) is used as an example of the carbon source. Figure 1 As shown, the method is as follows:

[0044] Step 1: Set N dosing intervals according to the redox potential difference ΔORP between the inlet and outlet water of the anoxic pool;

[0045] In this embodiment, the value of N is 5. According to the ΔORP range (-300mV to 0mV), 5 dosing intervals are set accordingly, as follows:

[0046] The judgment criteria for dosing interval 1 are: inlet and outlet water -300mV≤ΔORP≤-240mV;

[0047] The judgment criteria for dosing interval 2 are: -240mV<ΔORP≤-180mV;

[0048] The judgment criteria for dosing interval 3 are: -180mV<ΔORP≤-120mV;

[0049] The judgment criteria for dosing interval 4 are: -120mV<ΔORP≤-60mV;

[0050] The judgment criterion for the dosing interval 5 is: -60mV<ΔORP≤0mV.

[0051] Step 2: Collect the ORP values ​​of the inlet and outlet water of the anoxic pool, calculate the redox potential difference ΔORP between the inlet and outlet water of the anoxic pool, and determine the dosing interval to which it belongs;

[0052] like Figure 2 As shown, the ORP meter of the anoxic pool inlet water 9, the NO3 - The instrument 10 is installed at the water inlet of the anoxic tank, and the anoxic tank outlet water ORP instrument 11 is installed at the water outlet of the anoxic tank. The online detection data is collected to the intelligent dosing system 12 through the signal line;

[0053] The subsequent intelligent dosing system 12 uses the method of the present invention to collect the collected data (including the ORP value of the anoxic tank inlet and outlet water and the inlet NO3 - The final dosage is then fed back to the carbon source addition PLC control cabinet, and the PLC controls the flow rate through the carbon source addition flowmeter 3 to achieve control of the carbon source dosage.

[0054] Step 3: Collect NO3 from the anoxic pool - The average dosing concentration of each dosing interval is calculated according to formula (1);

[0055]

[0056] Where: [COD] represents the average dosing concentration, mg / L (in terms of COD concentration); [NO3 - ] indicates the NO3 in the aerobic pool effluent - Concentration, mg / L (in N); ΔORP represents the difference in redox potential between the inlet and outlet water of the anoxic pool, ΔORP = ORP 缺氧池进水 -ORP 缺氧池出水 , the range is -300mV~0mV.

[0057] For example: Get NO3 from the influent of the anoxic pool - The concentration is 5 mg / L. The average dosing concentration in each dosing interval is calculated according to formula (1):

[0058] The judgment criteria for dosing interval 1 are: inlet and outlet water -300mV≤ΔORP≤-240mV, and the average dosing concentration is: 7.23mg / L;

[0059] The judgment standard of dosing interval 2 is: -240mV<ΔORP≤-180mV, and the average dosing concentration is: 8.31mg / L;

[0060] The judgment criteria for dosing interval 3 are: -180mV<ΔORP≤-120mV, and the average dosing concentration is: 9.39mg / L;

[0061] The judgment criteria for dosing interval 4 is: -120mV<ΔORP≤-60mV, and the average dosing concentration is: 10.47mg / L;

[0062] The judgment criterion for dosing interval 5 is: -60mV<ΔORP≤0mV, and the average dosing concentration is: 11.55mg / L.

[0063] The ORP of the inlet and outlet water of the current anoxic pool are -400mV and -200mV respectively, the ΔORP is -200mV, and the dosing interval 2 is selected, and the dosing concentration is 8.31mg / L.

[0064] Another example: Get NO3 from the anoxic pool water - The concentration is 9 mg / L. The average dosing concentration in each dosing interval is calculated according to formula (5):

[0065] The judgment criteria for dosing interval 1 are: inlet and outlet water -300mV≤ΔORP≤-240mV, and the average dosing concentration is: 7.99mg / L;

[0066] The judgment standard of dosing interval 2 is: -240mV<ΔORP≤-180mV, and the average dosing concentration is: 9.07mg / L;

[0067] The judgment standard of dosing interval 3 is: -180mV<ΔORP≤-120mV, and the average dosing concentration is: 10.15mg / L;

[0068] The judgment criteria for dosing interval 4 is: -120mV<ΔORP≤-60mV, and the average dosing concentration is: 11.23mg / L;

[0069] The judgment criterion for dosing interval 5 is: -60mV<ΔORP≤0mV, and the average dosing concentration is: 12.31mg / L.

[0070] The ORP of the current anoxic pool inlet and outlet water are -300mV and -180mV respectively, the ΔORP is -120mV, and the dosing interval 3 is selected to obtain a dosing concentration of 10.15mg / L.

[0071] Step 4: Obtain the current raw water flow rate and calculate the carbon source dosage according to formula (2);

[0072]

[0073] Where M represents the amount of carbon source added, kg / h; n represents the compensation coefficient, NO3 - When the concentration is ≤8mg / L, n is 1; NO3 - When the concentration is greater than 8 mg / L, n is 2; [COD] represents the average dosing concentration, mg / L (measured in COD concentration); Q represents the flow rate of raw water, m 3 / h; a represents the COD equivalent value, which is dimensionless and the value in this example is 1.07.

[0074] For example, the current raw water flow is 20000m 3 / h, and the carbon source dosage is calculated according to formula (2).

[0075] Example 1: Obtaining NO3 from the influent of anoxic pool - The concentration is 5 mg / L, the average dosing concentration is 8.31 mg / L, and the acetic acid dosage is 155 kg / h;

[0076] Example 2: Obtaining NO3 from the influent of anoxic pool - The concentration is 9 mg / L, the average dosing concentration is 10.15 mg / L, and the acetic acid dosage is 379 kg / h.

[0077] Step 5: Accurately add the medicine according to the dosage calculated in step 4;

[0078] After determining the dosage, you can turn on the dosing pump to add medicine, and perform PID automatic adjustment according to the dosing flow collected by the dosing flow meter to ensure accurate dosing of the medicine.

[0079] Figure 3 This is the average dosage distribution diagram for sewage denitrification and phosphorus removal using the method of this application, combined with Figure 3 From formula (1), we can see that [COD] increases with [NO3 - ] and ΔORP. The more dosing intervals you set yourself, the more accurate the average dosing concentration will be.

[0080] To illustrate the effect of the present invention, this example compares the effect of manual dosing and the dosing method of the present invention. Figure 4A and Figure 4B As shown, after adding carbon source using the intelligent dosing method provided by this application, the NO3 - The average concentration is 1.57 mg / L, which is 56% lower than that of manual dosing, and the average TP concentration of the effluent is 0.2 mg / L. The average water intake within 30 days is 179,000 t / d, and the average drug consumption of manual dosing and intelligent dosing are 0.38 and 0.21 t acetic acid / 10,000 t water, respectively. After using the intelligent dosing method of the present invention, the carbon source dosage is saved by 45%.

[0081] Therefore, the carbon source intelligent dosing method of the present invention can ensure that NO3 - , TP can achieve stable emission standards, and can greatly save the amount of carbon source added, reduce the addition cost and carbon emissions, and at the same time reduce the labor intensity of operators, achieving the purpose of reducing costs, increasing efficiency, saving energy and reducing carbon emissions.

[0082] Some steps in the embodiments of the present invention may be implemented using software, and the corresponding software program may be stored in a readable storage medium, such as a CD or a hard disk.

[0083] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An intelligent dosing method for wastewater denitrification and phosphorus removal, characterized in that: The method comprises: Step 1, obtaining the redox potential difference ΔORP of the inlet and outlet water of the anoxic tank in the denitrification and phosphorus removal reaction tank, and setting N dosing intervals according to ΔORP; Step 2: Collect NO3 from the influent of the anoxic pool - The value is based on the redox potential difference ΔORP between the inlet and outlet water of the anoxic pool and the NO3 - The average dosing concentration in each dosing interval is calculated using the following values: Step 3, obtain the current raw water flow rate and calculate the dosage according to the following formula: Where M represents the amount of carbon source added; n represents the compensation coefficient; [COD] represents the average dosing concentration; Q represents the flow rate of raw water, m 3 / h; a represents COD equivalent value; Step 4, adding the corresponding carbon source into the anaerobic tank in the denitrification and phosphorus removal reaction tank according to the dosage calculated in step 3.

2. The method according to claim 1, characterized in that In step 2, the redox potential difference ΔORP of the inlet and outlet water of the anoxic pool and the NO3 - When calculating the average dosing concentration in each dosing interval, use the following formula: Wherein, [COD] represents the average dosing concentration, measured in COD concentration; [NO3 - ] indicates the NO3 in the aerobic pool effluent - Concentration; ΔORP represents the difference in redox potential between the inlet and outlet water of the anoxic pool, ΔORP = ORP 缺氧池进水 -ORP 缺氧池出水 .

3. The method according to claim 2, characterized in that The value of the compensation coefficient n in step 3 is 1 or 2: When NO3 - When the concentration is ≤8 mg / L, the value of n is 1; When NO3 - When the concentration is greater than 8 mg / L, the value of n is 2.

4. The method according to claim 3, characterized in that The method further comprises: Collect the ORP of the anoxic pool inlet and outlet water and the NO3 of the anoxic pool inlet water at each dosing. - The concentration is combined with the dosage to establish a training set, and the training set is used for machine learning to adjust the constant in the average dosage concentration formula, and then the average dosage concentration is calculated according to the adjusted formula.

5. The method according to claim 4, characterized in that The method is applied to a sewage denitrification and phosphorus removal system, which includes a carbon source dissolving device, a denitrification and phosphorus removal reaction tank, a carbon source dosing PLC control cabinet and an intelligent dosing system; the carbon source dissolving device is used to fully dissolve the added carbon source, and the denitrification and phosphorus removal reaction tank is provided with an anaerobic tank, an anoxic tank and an aerobic tank connected thereto, wherein the inlet and outlet of the anoxic tank are both provided with ORP meters for collecting the ORP values ​​of the inlet and outlet of the anoxic tank, and the inlet of the anoxic tank is also provided with a NO3 - Instrument for collecting NO3 in the anoxic pool inlet - value; the intelligent dosing system is used to adjust the ORP value of the inlet and outlet water of the anoxic pool and the inlet NO3 - The value determines the carbon source dosage, and then feeds back to the carbon source dosage PLC control cabinet, so that the carbon source dosage PLC control cabinet can add the carbon source that is fully dissolved in the carbon source dissolution device to the anaerobic tank of the denitrification and phosphorus removal reaction tank according to the carbon source dosage.

6. The method according to claim 1, characterized in that A mixed liquid reflux pump is provided between the aerobic pool outlet and the anoxic pool inlet, and the mixed liquid reflux pump is used to make the aerobic pool outlet flow back to the anoxic pool inlet.

7. The method according to claim 5, characterized in that The carbon source addition PLC control cabinet adopts a PID control strategy when adding the carbon source according to the carbon source addition amount.

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