A device for screening external carbon sources for sewage treatment and its use method

Abstract

The present invention relates to a device for screening external carbon sources for sewage treatment and a method for using the device, which is provided with a triangular flask, a bottle stopper, a syringe with a long needle, a hose, a hard tube, a magnetic rotor, a magnetic stirrer and a beaker; the bottle mouth of the triangular flask is provided with a bottle stopper; the bottle stopper is provided with a needle hole for the long needle of the syringe to pass through and a hard tube mounting hole for the hard tube to pass through; the syringe is installed on the needle hole; the hard tube is passed through the mounting hole, the upper end of which is connected to the hose, and the lower end is located in the triangular flask; one end of the hose is installed on the upper end of the hard tube, and the other end of the hose is inserted into the pure water of the beaker; the magnetic rotor is arranged at the bottom of the bottle in the triangular flask; the triangular flask is placed on the magnetic stirrer. The present invention is suitable for screening external carbon sources for sewage treatment, and has the advantages of reasonable structural design and convenient operation. Establishing an external carbon source performance evaluation method based on test data can efficiently select cost-effective external carbon sources, meet the use needs of sewage treatment plants, and save external carbon source costs.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to a sewage treatment external carbon source screening device and a use method thereof. Background Art

[0002] As people's requirements for environmental quality continue to increase, local governments have also increased their requirements for emission standards, and more and more projects have been launched to improve standards. For many sewage treatment plants with a low ratio of influent organic matter to total nitrogen (TN), adding an external carbon source has become a key measure to ensure that the effluent total nitrogen meets the standard. If high-quality carbon sources are not scientifically selected, the cost of the carbon source will be high, which will often put a certain amount of pressure on the operating costs of the sewage treatment plant. There are a variety of carbon sources in society, including a variety of composite carbon sources. How to scientifically and rationally select a carbon source with a high cost performance is of great significance to reducing the carbon source cost and improving the TN treatment effect for sewage treatment projects. The present invention is proposed based on this research background, and aims to provide an external carbon source screening device for sewage treatment and a method of using the same, so as to achieve scientific and rational selection of a carbon source with a high cost performance. Summary of the invention

[0003] In view of this, the purpose of the present invention is to provide a sewage treatment external carbon source screening device and its use method, which has the advantages of reasonable structural design and convenient operation and use. Based on the data of the screening test, an external carbon source evaluation system is established, which can quickly and efficiently select a cost-effective carbon source, meet the use needs of the sewage treatment plant, and save the cost of the external carbon source.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A device for screening external carbon sources for sewage treatment, characterized in that: a triangular flask, a bottle stopper, a syringe with a long needle, a hose, a hard tube, a magnetic rotor, a magnetic stirrer and a beaker are provided; the bottle mouth of the triangular flask is provided with a bottle stopper; the mixed solution consisting of the external carbon source, muddy water at the end of the anoxic pool, i.e., bottom mud, and nitrate is contained in the triangular flask; the bottle stopper is provided with a needle hole for the long needle of the syringe to pass through and a mounting hole for the hard tube to pass through; the syringe with the long needle is installed on the needle hole; the hard tube is passed through the mounting hole, the upper end of which is connected to the hose, and the lower section is located in the triangular flask; one end of the hose is installed on the upper end of the hard tube; the other end of the hose is inserted into the pure water in the beaker; the beaker contains pure water of a preset height; the magnetic rotor is arranged at the bottom of the bottle in the triangular flask; the triangular flask is arranged on the magnetic stirrer, and the mixed solution in the triangular flask is stirred by the cooperation of the magnetic rotor and the magnetic stirrer.

[0006] The optimization scheme for further implementing and improving the external carbon source screening device for sewage treatment of the present invention is:

[0007] The volume of the triangular flask is 0.5L-5L, and the lower end of the hard tube is 2-4cm higher than the liquid level of the mixed liquid in the triangular flask.

[0008] The length of the long needle is 15-30 cm, the lower end of the long needle is inserted below the liquid surface of the mixed liquid, and the upper end of the long needle is connected to the lower end of the syringe body, so that the reaction liquid in the conical flask can be taken multiple times without removing the long needle.

[0009] The needle of the long needle is also provided with a needle sealing ring that matches the shape of the needle hole; the hard tube is also provided with a hard tube sealing ring that matches the shape of the hard tube installation hole.

[0010] The needle sealing ring and the hose sealing ring are both truncated cone sealing rings with an isosceles trapezoidal longitudinal section; an annular reinforcement ring is embedded in the outer circumference of the truncated cone sealing ring; the annular reinforcement ring is an elastic steel ring, the outer wall of the sealing ring is tightly sealed with the bottle cap, and the inner wall is tightly sealed with the long needle and the hard tube respectively.

[0011] The method for using the external carbon source screening device for sewage treatment of the present invention is characterized in that the method for using comprises the following steps, and the detection methods that are not described in detail in the following steps are all existing well-known methods and will not be described in detail:

[0012] 1) Preparation of test materials:

[0013] a) The muddy water at the end of the anoxic pool is used as the bottom mud, and the mixed suspended solid concentration MLSS, chemical oxygen demand COD, and total nitrogen TN of the bottom mud are measured and calculated as D TN0 , Nitrate nitrogen The concentration is D 硝0 , place the bottom mud in a cool place at 10-25℃ for later use;

[0014] b) prepare potassium nitrate standard solution, the concentration of potassium nitrate standard solution is 1-2g / L, and keep it for future use;

[0015] c) preparing an external carbon source solution: taking a solid external carbon source powder or a solution external carbon source, the powder needs to be dissolved in purified water, and the chemical oxygen demand COD is used as a characterization index. The chemical oxygen demand COD of the external carbon source on the market is generally 20-100 g / L; diluting the external carbon source to a chemical oxygen demand COD concentration of 10-20 g / L according to the COD index of the external carbon source product, and leaving it for use in step 2);

[0016] d) When monitoring nitrate nitrogen in sediment When the concentration is lower than 20 mg / L, add potassium nitrate standard solution to the sediment until the nitrate concentration is The concentration F reaches 20-40 mg / L; at this time, the TN concentration in the sediment is calculated as D TN前 =DTN0 -D 硝0 +F;

[0017] 2) Specific experimental steps:

[0018] a) Take 2-10L of the sludge prepared in the previous step, and take the volume of the selected flask as the basis. The volume of the sludge is the sum of the volume of the flask multiplied by the number of carbon sources to be detected plus 1;

[0019] b) Adding materials: Take a conical flask and add the sediment liquid level in step a) after shaking to the maximum scale of the conical flask; add the external carbon source solution prepared above to the conical flask respectively, and the concentration of the external carbon source solution in the sediment is 1:1. - 3-N concentration F is 4-6 times, and the amount of external carbon source and volume V to be added are calculated based on the volume of the bottom mud in the triangular bottle. 外碳源 ; and record the V of the added external carbon source 外碳源 , in order to calculate the cost; the above three types of substances constitute the experimental mixed solution, the volume of the mixed solution is set to V, V = the maximum scale value of the conical flask + V 外碳源 ;

[0020] c) Keep another comparative flask and add the same amount of sediment and potassium nitrate standard solution as in step b), without adding an external carbon source, but add the same amount of distilled water as the external carbon source in the other flasks, as a blank control;

[0021] d) Place the flask on the tray of the magnetic stirrer, put in the magnetic rotor, adjust the speed of the magnetic rotor to 300-500rpm, and adjust the speed to produce a small vortex during stirring but without gas inhalation to prevent oxygen from entering; insert a 15-30cm long needle into one of the two holes of the flask mouth 4-6cm below the water surface, and the lower end of the hard tube is 2-4cm above the liquid surface in the flask, and the other end of the hose is immersed in a beaker containing distilled water to exhaust nitrogen;

[0022] e) Stirring sampling: Sampling is done once every 0.25-1 hour, and sampling can be done 1-6 times. The total reaction time is H. After each reaction time, let it settle for 5-10 minutes before sampling. Take 10-15mL of supernatant each time, filter it with a 0.45 micron filter membrane, and determine the chemical oxygen demand COD and total nitrogen TN of the supernatant after the reaction. When sampling each time, the long needle does not move, and the syringe can be replaced after the sampling is completed. The chemical oxygen demand COD value of the supernatant measured by the last sampling is set as EFF COD , the total nitrogen TN value is set as EFF TN ;

[0023] f) The above steps are performed once for each external carbon source to be tested, and the results are recorded; the control flask is also operated once, and the results are recorded;

[0024] g) Establish a method for evaluating the performance of external carbon sources, calculate the nitrogen removal cost COST according to the cost of removing one unit of total nitrogen, and the one with the lower unit nitrogen removal cost COST is the better external carbon source;

[0025] The total nitrogen TN value of the mixed solution in the blank triangular flask after the reaction is calculated as EFF TN空白 , the total nitrogen removal after the reaction is completed is set as M 空白 , M 空白 =(TN 前 -EFF TN空白 )*V;

[0026] The cost of adding the external carbon source in the triangular flask is set as D, and the total nitrogen TN value after the reaction is calculated as EFF TN The amount of total nitrogen TN removed from the flask containing the external carbon source solution is set as M S , M S =(TN 前 -EFF TN )*V;

[0027] The actual amount of total nitrogen removed by the external carbon source solution is △TN M S -M 空白 ,This part takes into account the contribution of sediment to the removal of total nitrogen, and can more scientifically judge the contribution of external carbon sources to the removal of total nitrogen;

[0028] Unit denitrification cost COST = D / △TN.

[0029] The optimization scheme for further improving and implementing the method of using the external carbon source screening device for sewage treatment of the present invention is:

[0030] Establish a method for judging the performance of external carbon sources, calculate the unit denitrification cost COST and the amount of chemical oxygen demand COD required for unit denitrification as Q, calculate the weighted scores respectively, add the two together, and the one with the higher comprehensive score is the better external carbon source;

[0031] a) Unit denitrification cost COST = D / △TN, the weight value of this indicator is q COST The highest score is 10 and the lowest score is 5.

[0032] The unit nitrogen removal cost COST of the external carbon sources participating in the evaluation is sorted from small to large. The one with the smallest unit nitrogen removal cost COST is set to M, and the weight value of M is 10 points. The one with the largest unit nitrogen removal cost COST is set to K, and the weight value of K is 5 points. The unit nitrogen removal cost COST weight scores of the remaining external carbon sources are calculated according to the following formula:

[0033] The weight value q of the unit nitrogen removal cost COST of a certain external carbon source COST =10-(COST-M)*(10-5) / (KM)

[0034] b) In the experiment, △COD is set as the chemical oxygen demand COD of the added external carbon source;

[0035] The amount of chemical oxygen demand (COD) required for unit denitrification is set as Q, Q = △COD / △TN, and the weight value of this indicator is q q The highest score can be 10 points, and the lowest score can be 5 points;

[0036] The amount Q of chemical oxygen demand (COD) required for unit denitrification of the external carbon sources participating in the evaluation is sorted from small to large. The one with the smallest amount Q of chemical oxygen demand (COD) required for unit denitrification is set as P, and the weight value of P is 10 points. The largest one is set as S, and the weight value of S is 5 points. The weight scores of the amount Q of chemical oxygen demand (COD) required for unit denitrification of the remaining external carbon sources are calculated according to the following formula:

[0037] q q =10-(QP)*(10-5) / (SP)

[0038] The above two weight indicators of each external carbon source are added together and then sorted. The one with a higher comprehensive score is the better carbon source.

[0039] Further improvement and optimization plan: Establish an external carbon source performance evaluation method, calculate the unit nitrogen removal cost COST, calculate the amount of chemical oxygen demand COD required for unit nitrogen removal, calculate the denitrification rate DNR, calculate the weighted scores respectively, add the three together, and the one with the highest comprehensive score is the better external carbon source;

[0040] a) Unit denitrification cost COST = D / △TN, the weight value of this indicator is q COST The highest score is 10 and the lowest score is 5.

[0041] The unit nitrogen removal cost COST of the external carbon sources participating in the evaluation is sorted from small to large. The one with the smallest unit nitrogen removal cost COST is set to M, and the weight value of M is 10 points. The one with the largest unit nitrogen removal cost COST is set to K, and the weight value of K is 5 points. The unit nitrogen removal cost COST weight scores of the remaining external carbon sources are calculated according to the following formula:

[0042] The weight value q of the unit nitrogen removal cost COST of a certain external carbon source COST =10-(COST-M)*(10-5) / (KM)

[0043] b) In the experiment, △COD is set as the chemical oxygen demand COD of the added external carbon source;

[0044] The amount of chemical oxygen demand (COD) required for unit denitrification is set as Q, Q = △COD / △TN, and the weight value of this indicator is q q The highest score can be 10 points, and the lowest score can be 5 points;

[0045] The amount Q of chemical oxygen demand (COD) required for unit denitrification of the external carbon sources participating in the evaluation is sorted from small to large. The one with the smallest amount Q of chemical oxygen demand (COD) required for unit denitrification is set as P, and the weight value of P is 10 points. The largest one is set as S, and the weight value of S is 5 points. The weight scores of the amount Q of chemical oxygen demand (COD) required for unit denitrification of the remaining external carbon sources are calculated according to the following formula:

[0046] q q =10-(QP)*(10-5) / (SP)

[0047] c) Denitrification rate DNR = △TN / mixed suspended solid concentration MLSS / reaction time, where the reaction time is the total reaction time set to H, and the weight value of this indicator is set to q DNR ,q DNR The highest weight is set at 8 points and the lowest is set at 5 points;

[0048] The denitrification rates DNR of the external carbon sources participating in the evaluation are sorted from small to large. The one with the smallest denitrification rate DNR is set as T, and the weight value of T is 5 points. The largest one is set as W, and the weight value of W is 8 points. The weight scores of the denitrification rates DNR of the remaining external carbon sources are calculated according to the following formula:

[0049] q DNR =8-(W-DNR)*(8-5) / (WT)

[0050] The above three weight indicators of each external carbon source are added together and then sorted. The one with a higher comprehensive score is the better carbon source.

[0051] Further improvement and implementation of the optimization plan: establish an external carbon source performance evaluation method, calculate the unit nitrogen removal cost COST, calculate the amount of chemical oxygen demand COD required for unit nitrogen removal, calculate the denitrification rate DNR, detect the chemical oxygen demand COD value in the water after the reaction, and detect the total nitrogen TN value in the water after the reaction, calculate the weighted scores respectively, add up the five, and the one with the highest comprehensive score is the better external carbon source;

[0052] a) Unit denitrification cost COST = D / △TN, the weight value of this indicator is q COST The highest score is 10 and the lowest score is 5.

[0053] The unit nitrogen removal cost COST of the external carbon sources participating in the evaluation is sorted from small to large. The one with the smallest unit nitrogen removal cost COST is set to M, and the weight value of M is 10 points. The one with the largest unit nitrogen removal cost COST is set to K, and the weight value of K is 5 points. The unit nitrogen removal cost COST weight scores of the remaining external carbon sources are calculated according to the following formula:

[0054] The weight value q of the unit nitrogen removal cost COST of a certain external carbon source COST =10-(COST-M)*(10-5) / (KM)

[0055] b) In the experiment, △COD is set as the chemical oxygen demand COD of the added external carbon source;

[0056] The amount of chemical oxygen demand (COD) required for unit denitrification is set as Q, Q = △COD / △TN, and the weight value of this indicator is q q The highest score can be 10 points, and the lowest score can be 5 points;

[0057] The amount Q of chemical oxygen demand (COD) required for unit denitrification of the external carbon sources participating in the evaluation is sorted from small to large. The one with the smallest amount Q of chemical oxygen demand (COD) required for unit denitrification is set as P, and the weight value of P is 10 points. The largest one is set as S, and the weight value of S is 5 points. The weight scores of the amount Q of chemical oxygen demand (COD) required for unit denitrification of the remaining external carbon sources are calculated according to the following formula:

[0058] q q =10-(QP)*(10-5) / (SP)

[0059] c) Denitrification rate DNR = △TN / mixed suspended solids concentration MLSS / reaction time H, the weight value of this indicator is q DNR The highest score can be 8 points, and the lowest score can be 5 points;

[0060] The denitrification rates DNR of the external carbon sources participating in the evaluation are sorted from small to large. The one with the smallest denitrification rate DNR is set as T, and the weight value of T is 5 points. The largest one is set as W, and the weight value of W is 8 points. The weight scores of the denitrification rates DNR of the remaining external carbon sources are calculated according to the following formula:

[0061] q DNR =8-(W-DNR)*(8-5) / (WT)

[0062] d) The COD value of the water after the reaction of the external carbon source involved in the evaluation COD The highest weight is 5 points, the lowest is 2 points, and the smallest COD value in the water after the reaction is ranked from small to large. The smallest COD value in the water after the reaction is U, and the weight value of U is 5 points. The largest value is J, and the weight value of J is 2 points. The weight scores of the COD values ​​in the water after the reaction of other external carbon sources are calculated according to the following formula:

[0063] q EFFCOD =5-(EFF COD -U)*(5-2) / (JU)

[0064] e) The total nitrogen TN value EFF in the water after the reaction of the external carbon source involved in the evaluation TN The highest weight is 5 points, the lowest is 2 points, and the smallest TN value in the water after the reaction is ranked from small to large. The smallest TN value in the water after the reaction is X, and the weight value of X is 5 points. The largest value is Y, and the weight value of Y is 2 points. The weight scores of the TN values ​​of the water after the reaction of other external carbon sources are calculated according to the following formula:

[0065] q EFFTN =5-(EFF TN -X)*(5-2) / (YX)

[0066] The weights of the above five indicators of each external carbon source are added together, and then sorted. The one with a higher comprehensive score is the better carbon source.

[0067] Another simple implementation scheme: It is characterized by the following steps. The detection and inspection methods used in the claims are commonly known methods in the industry and are not described in detail:

[0068] 1) Preparation of test materials:

[0069] a) Use the muddy water at the end of the normal operating sewage treatment anoxic tank as the bottom mud, measure the amount of mixed suspended volatile solids, the content of denitrifying bacteria, pH value, and temperature in the bottom mud, and adjust them to the normal value of the anoxic tank for normal denitrification reaction. The adjustment range is: mixed suspended volatile solids: 50%-70%, denitrifying bacteria content: 5%-25%, pH value: 6-8, temperature: 15-30℃;

[0070] b) Determine the nitrate concentration in the sediment. When the nitrate content of the sediment is lower than 20 mg / L, add potassium nitrate solution to make the nitrate content F of the sediment reach 20-40 mg / L for standby use;

[0071] c) preparing an external carbon source solution: taking a solid external carbon source powder with a powder fineness of 200-300 mesh, or an external carbon source solution, dissolving the powder in purified water to a concentration of 20-40 g / L, and diluting the original external carbon source solution with purified water to a concentration of 10-20 g / L;

[0072] d) Prepare comparative conical flasks and auxiliary devices of the same specifications;

[0073] 2) Specific screening experimental steps:

[0074] a) Take 3 liters of sediment and pour them into the flasks respectively, with the liquid level and the highest scale line of the flasks level; take the external carbon source solution prepared in step 1), the concentration of the external carbon source solution in the sediment is nitrate NO in the sediment. - 3-N concentration F is 4-6 times, and the amount of external carbon source and volume V to be added are calculated based on the volume of the bottom mud in the triangular bottle. 外碳源 ; and record the V of the added external carbon source 外碳源 , in order to calculate the cost; the above three types of substances constitute the experimental mixed solution, the volume of the mixed solution is set to V, V = the maximum scale value of the conical flask + V 外碳源 ;

[0075] b) placing a conical flask on the tray of a magnetic stirrer, inserting a magnetic rotor, adjusting the speed of the magnetic rotor to 300-500 rpm, and adjusting the speed to produce a small vortex during stirring but without gas inhalation to prevent the entry of oxygen; inserting the long needle of the syringe on the conical flask stopper 4-6 cm below the liquid surface in the conical flask, keeping the lower end of the hard tube 2-4 cm above the liquid surface in the conical flask, and immersing the other end of the hose in a beaker containing distilled water for exhausting nitrogen;

[0076] c) Stirring sampling: Sampling is performed once every 0.25-1 hour, and sampling can be performed 1-6 times, with a total reaction time of 2-4 hours. After each reaction time, the mixed solution is allowed to settle in the conical flask for 5-10 minutes, and 10-15 mL of supernatant is taken. During each sampling, the long needle does not move, and the syringe can be replaced after the sampling is completed; the supernatant is filtered with a 0.45 micron filter membrane, and then the nitrate concentration of each supernatant is measured respectively;

[0077] d) Calculate and test the denitrification effect of the external carbon source: Calculate the denitrification rate of the external carbon source according to the concentration of nitrate in the sediment after the reaction measured each time, and record it; the detection method of nitrate concentration and the calculation method of denitrification rate are conventional known methods;

[0078] e) performing steps a) to d) of the above method once for each external carbon source to be tested, and recording the results respectively; and performing the same test once using a control flask and auxiliary device with an equal amount of distilled water added but without the external carbon source solution, and recording the results;

[0079] f) Calculate the actual denitrification efficiency of the external carbon source: subtract the denitrification efficiency of each external carbon source added in the above steps from the denitrification efficiency of the control triangular flask without the external carbon source added, and obtain the denitrification efficiency value actually generated by the external carbon source;

[0080] g) Determine the cost performance of the external carbon source: Calculate the cost price of the external carbon source according to the amount of net external carbon source contained in the external carbon source solution obtained in each external carbon source test, which is a comprehensive cost including procurement, storage, transportation and processing costs; and the actual denitrification efficiency value of the external carbon source, which is calculated by dividing the last denitrification rate obtained in the previous step by the total cost price as the unit denitrification cost of the external carbon source;

[0081] h) Cost-effectiveness list of external carbon sources: a cost-effectiveness list of several external carbon sources, arranged from high to low in terms of cost-effectiveness, with the high-quality external carbon sources having the highest cost-effectiveness being high-quality external carbon sources, and thus the required high-quality external carbon sources with low cost and high denitrification rate can be screened out;

[0082] i) Prepare a denitrification rate list: Arrange the denitrification rates detected in the supernatant of each external carbon source in order of the time of removal. The one with the fastest denitrification rate is a high-quality external carbon source with a high denitrification rate. The external carbon source with a high denitrification rate can be selected. The more ideal external carbon source can be screened out by comprehensively considering the denitrification rate cost-effectiveness and denitrification rate.

[0083] The sewage treatment external carbon source screening device and the use method thereof of the present invention have the following beneficial effects:

[0084] (1) The screening device has a reasonable structural design and is easy to use. The external carbon source screening device for sewage treatment can provide ideal environmental conditions for the denitrification process, and can achieve multiple water sampling at different reaction times during the experiment to ensure that no oxygen enters the triangular flask during the experiment.

[0085] (2) By utilizing the cooperation between the magnetic stirrer and the magnetic rotor, the screening device can achieve stable and reliable stirring during use, and through the connection relationship between the conical flask, the bottle stopper, the syringe with a long needle, the hose, the hard tube, the magnetic rotor, the magnetic stirrer and the beaker, it can provide effective and reliable conditions for the screening of external carbon sources.

[0086] (3) This method establishes a variety of relatively complete and optional external carbon source performance evaluation methods, which comprehensively evaluate indicators such as unit denitrification cost, chemical oxygen demand required for unit denitrification, denitrification rate, COD value in the water after reaction, and TN value in the water after reaction. It can accurately screen out the ideal external carbon source with the highest comprehensive cost-effectiveness. The screening is fast, scientific, and the evaluation is objective. BRIEF DESCRIPTION OF THE DRAWINGS

[0087] Figure 1 It is a schematic structural diagram of the external carbon source screening device for sewage treatment of the present invention.

[0088] Figure 2 This is a schematic diagram of the bottle stopper drilling of the sewage treatment external carbon source screening device of the present invention. DETAILED DESCRIPTION

[0089] The following is an explanation of a sewage treatment external carbon source screening device and a method of using the device in conjunction with the accompanying drawings.

[0090] Select 3 external carbon sources: liquid external carbon source A, liquid external carbon source B, and liquid external carbon source C to evaluate the cost performance:

[0091] Embodiment 1: A device for screening external carbon sources for sewage treatment, comprising a transparent organic glass triangular flask 1, a bottle stopper 2, a syringe with a long needle 3, a hose 4, a hard tube 5, a magnetic rotor 6, a magnetic stirrer 7 and a beaker 8; the mouth of the triangular flask is provided with a bottle stopper; a mixed solution consisting of the external carbon source, muddy water at the end of anoxic pool, i.e., bottom mud, and nitrate is contained in the triangular flask; the bottle stopper is provided with a needle hole for the long needle of the syringe to pass through and a mounting hole for the hard tube to pass through; the syringe with the long needle is mounted on the needle hole; the hard tube is passed through the mounting hole, the upper end of which is connected to the hose, and the lower section is located in the triangular flask; one end of the hose is mounted on the upper end of the hard tube; the other end of the hose is inserted into the pure water in the beaker; the beaker contains pure water of a preset height; the magnetic rotor is arranged at the bottom of the bottle in the triangular flask; the triangular flask is arranged on the magnetic stirrer, and the mixed solution in the triangular flask is stirred by the cooperation of the magnetic rotor and the magnetic stirrer.

[0092] The volume of the triangular flask is 3L, and the outer wall of the flask is engraved with volume scales. The lower end of the hard tube is 3cm above the liquid level of the mixed liquid in the triangular flask. The length of the long needle is 20cm. When in use, the lower end of the long needle is inserted below the liquid level of the mixed liquid, and it drops as the liquid level drops when taking the liquid. The upper end of the long needle is connected to the lower end of the syringe body, which is convenient for taking the reaction liquid in the triangular flask multiple times without taking out the long needle. A needle seal ring that matches the shape of the needle hole is also provided on the needle of the long needle; a hard tube seal ring that matches the shape of the hard tube mounting hole is also provided on the hard tube. The needle seal ring and the hose seal ring are both truncated cone-shaped seal rings with an isosceles trapezoidal longitudinal section; an annular reinforcement ring is embedded in the outer peripheral surface of the truncated cone-shaped seal ring; the annular reinforcement ring is an elastic steel ring, the outer wall of the seal is tightly sealed with the bottle cap, and the inner wall is tightly sealed with the long needle and the hard tube respectively.

[0093] The method of using the external carbon source screening device for sewage treatment in this embodiment includes the following steps. The detection methods not described in the following steps are all existing well-known methods and will not be described in detail:

[0094] 1) Preparation of test materials:

[0095] a) The uniform mud water at the end of the anoxic tank in operation in a sewage treatment plant was used as the bottom mud. First, the mixed suspended solid concentration MLSS, chemical oxygen demand COD, and total nitrogen TN of the bottom mud were measured and calculated as D TN0、Nitric nitrogen NO - 3-N0 concentration is D 硝0 , record the data for later use, and place the bottom mud in a cool place at 10-25℃ for later use; after measurement, the mixed suspended solid concentration MLSS of the bottom mud was 4.2g / L, the chemical oxygen demand COD was 25mg / L, the total nitrogen TN was 8mg / L, and the nitrate nitrogen NO - The 3-N concentration is 5 mg / L, and the bottom mud is placed in a cool place at 22°C for later use;

[0096] b) Prepare 1L of potassium nitrate standard solution with a concentration of 1g / L and keep it for future use;

[0097] c) preparing an external carbon source solution: dilute the external carbon source solution A, external carbon source solution B and external carbon source C used in the examples to a chemical oxygen demand (COD) concentration of 10 g / L according to the COD index of the product, prepare 0.5 liter of each diluted solution, record the amount of the original solution used, and calculate its price for standby use, and the prepared diluted external carbon source solution is reserved for step 2);

[0098] d) When monitoring nitrate nitrogen in sediment Concentration D 硝0 When the nitrate concentration is lower than 20 mg / L, add potassium nitrate standard solution to the sediment until the nitrate concentration is The concentration is set to F and reaches 25 mg / L; at this time, the total nitrogen TN value in the sediment is set to D TN前 , D TN前 =D TN0 -D 硝0 +F = 8-5 + 25 = 28 mg / L;

[0099] 2) Specific experimental steps:

[0100] a) Take 4 L of the sludge prepared in the previous step, and use a 1 L flask. The volume of the sludge is the sum of the volume of the flask multiplied by the number of carbon sources to be tested (3 plus 1), which is 4;

[0101] b) Adding materials: Take a conical flask and add the sediment liquid level in step a) after shaking until it is 1L away from the maximum scale of the conical flask; add the external carbon source solution prepared above to the conical flask respectively, and the concentration of the external carbon source solution in the sediment is 1:1. - 3-4 times of N concentration F, calculate the amount of external carbon source dilution solution and the volume of external carbon source V to be added based on the volume of the bottom mud in the triangular bottle 外碳源 for 10L ; and record the V of the added external carbon source 外碳源 , in order to calculate the cost; the above three types of substances constitute the experimental mixed solution, the volume of the mixed solution is set to V, V = the maximum scale value of the conical flask + V 外碳源 ;

[0102] c) Keep another comparative flask and add the same amount of sediment and potassium nitrate standard solution as in step b), without adding an external carbon source, but add the same amount of distilled water as the external carbon source in the other flasks, as a blank control;

[0103] d) Place the conical flask on the tray of the magnetic stirrer, put in the magnetic rotor, adjust the speed of the magnetic rotor to 300-500rpm, and adjust the speed to produce a small vortex during stirring but without gas inhalation to prevent oxygen from entering; insert a 20cm long needle into one of the two holes of the conical flask mouth 5cm below the water surface, and the lower end of the hard tube is 3cm above the liquid surface in the conical flask, and the other end of the hose is immersed in a beaker containing distilled water to exhaust nitrogen;

[0104] e) Stirring sampling: Sampling was performed once every 0.5 hours, and the sampling could be performed 4 times. The total reaction time was set as H, where H was 2 hours. After each reaction time, the mixture was allowed to settle for 10 minutes before sampling. 15 mL of the supernatant was taken each time, and the chemical oxygen demand (COD) and total nitrogen (TN) of the supernatant after the reaction was completed were determined after filtering with a 0.45 μm filter membrane. During each sampling, the long needle was kept still, and the syringe could be replaced after the sampling was completed. The COD value of the supernatant measured by the last sampling was set as EFF. COD , the total nitrogen TN value is set as EFF TN ;

[0105] f) The above steps are performed once for each external carbon source to be tested, and the results are recorded; the control flask is also operated once, and the results are recorded; the results of external carbon source A, external carbon source B, external carbon source C, and control flask are:

[0106] External carbon source A: EFF COD =13mg / L, EFF TN =13.4mg / L

[0107] External carbon source B: EFF COD =19mg / L, EFF TN =12.9mg / L

[0108] External carbon source C: EFF COD =55mg / L, EFF TN =12.7mg / LControl bottle: EFF COD =13mg / L, EFF TN =26.3mg / L

[0109] g) Establish a method for evaluating the performance of external carbon sources, calculate the nitrogen removal cost COST according to the cost of removing one unit of total nitrogen, and the one with the lower unit nitrogen removal cost COST is the better external carbon source;

[0110] The total nitrogen TN value of the mixed solution in the blank triangular flask after the reaction is calculated as EFF TN空白 , the total nitrogen removal after the reaction is completed is set as M 空白 , M 空白 =(TN 前 -EFF TN空白 )*V;

[0111] The cost of adding the external carbon source in the triangular flask is set as D, and the total nitrogen TN value after the reaction is calculated as EFF TN The amount of total nitrogen TN removed from the flask containing the external carbon source solution is set as M S , M S =(TN 前 -EFF TN )*V;

[0112] The actual amount of total nitrogen removed by the external carbon source solution is △TN M S -M 空白 ,This part takes into account the contribution of sediment to the removal of total nitrogen, and can more scientifically judge the contribution of external carbon sources to the removal of total nitrogen;

[0113] Unit denitrification cost COST = D / △TN.

[0114] The results of external carbon source A, external carbon source B, and external carbon source C are:

[0115] External carbon source A: COST = 6.1 yuan / kgCOD

[0116] External carbon source B: COST = 4.3 yuan / kgCOD

[0117] External carbon source C: COST = 8.0 yuan / kgCOD, which shows that external carbon source B is a better external carbon source.

[0118] Example 2: A method for using a device for screening an external carbon source for sewage treatment. Using the device and operation method in Example 1, a method for evaluating the performance of an external carbon source is established. The method for calculating the unit nitrogen removal cost COST is the same and will not be repeated. In addition, the following tests and calculations are performed:

[0119] The unit denitrification cost COST and the amount of chemical oxygen demand COD required for unit denitrification are set as Q, and the weighted scores are calculated respectively. The two are added together, and the one with the higher comprehensive score is the better external carbon source;

[0120] a) Unit denitrification cost COST = D / △TN, the weight value of this indicator is q COST The highest score is 10 and the lowest score is 5.

[0121] The unit nitrogen removal cost COST of the external carbon sources participating in the evaluation is sorted from small to large. The one with the smallest unit nitrogen removal cost COST is set to M, and the weight value of M is 10 points. The one with the largest unit nitrogen removal cost COST is set to K, and the weight value of K is 5 points. The unit nitrogen removal cost COST weight scores of the remaining external carbon sources are calculated according to the following formula:

[0122] The weight value q of the unit nitrogen removal cost COST of a certain external carbon source COST =10-(COST-M)*(10-5) / (KM)

[0123] b) In the experiment, △COD is set as the chemical oxygen demand COD of the added external carbon source;

[0124] The amount of chemical oxygen demand (COD) required for unit denitrification is set as Q, Q = △COD / △TN, and the weight value of this indicator is q q The highest score can be 10 points, and the lowest score can be 5 points;

[0125] The amount Q of chemical oxygen demand (COD) required for unit denitrification of the external carbon sources participating in the evaluation is sorted from small to large. The one with the smallest amount Q of chemical oxygen demand (COD) required for unit denitrification is set as P, and the weight value of P is 10 points. The largest one is set as S, and the weight value of S is 5 points. The weight scores of the amount Q of chemical oxygen demand (COD) required for unit denitrification of the remaining external carbon sources are calculated according to the following formula:

[0126] q q =10-(QP)*(10-5) / (SP)

[0127] The above two weight indicators of each external carbon source are added together and then sorted. The one with a higher comprehensive score is the better carbon source.

[0128] The results of external carbon source A, external carbon source B, and external carbon source C are:

[0129] External carbon source A: 12.6

[0130] External carbon source B: 18.6

[0131] External carbon source C: 15.0

[0132] It can be seen that the external carbon source B is the better external carbon source.

[0133] Example 3: A method for using a device for screening an external carbon source for sewage treatment. Using the device and operation method in Example 1, a method for evaluating the performance of an external carbon source is established to calculate the denitrification cost COST, the amount of chemical oxygen demand COD required for unit denitrification, and the denitrification rate DNR, and the weighted scores are calculated respectively. The three are added together, and the one with the highest comprehensive score is the better external carbon source; wherein the unit denitrification cost COST = D / △TN, and the weight value of this indicator q COST, the amount of chemical oxygen demand (COD) required for unit denitrification is set as Q, Q = △COD / △TN, and the weight value of this indicator is q q The same as Example 2, no further details are given;

[0134] In addition, denitrification rate DNR = △TN / mixed suspended solid concentration MLSS / reaction time, the reaction time is the total reaction time set to H, and the weight value of this indicator is set to q DNR ,q DNR The highest weight is set at 8 points and the lowest is set at 5 points;

[0135] The denitrification rates DNR of the external carbon sources participating in the evaluation are sorted from small to large. The one with the smallest denitrification rate DNR is set as T, and the weight value of T is 5 points. The largest one is set as W, and the weight value of W is 8 points. The weight scores of the denitrification rates DNR of the remaining external carbon sources are calculated according to the following formula:

[0136] q DNR =8-(W-DNR)*(8-5) / (WT)

[0137] The above three weight indicators of each external carbon source are added together and then sorted. The one with a higher comprehensive score is the better carbon source.

[0138] The results of external carbon source A, external carbon source B, and external carbon source C are:

[0139] External carbon source A: 17.6

[0140] External carbon source B: 25.8

[0141] External carbon source C: 23.0

[0142] It can be seen that the external carbon source B is the better external carbon source.

[0143] Embodiment 4: A method for using an external carbon source screening device for sewage treatment, using the device and operating method in Embodiment 1, to establish an external carbon source performance evaluation method, calculate the unit denitrification cost COST, calculate the amount of chemical oxygen demand COD required for unit denitrification, calculate the denitrification rate DNR, detect the chemical oxygen demand COD value in the water after the reaction, and detect the total nitrogen TN value index in the water after the reaction, and calculate the weighted scores respectively, add the five together, and the one with the highest comprehensive score is the better external carbon source; wherein the method for calculating the unit denitrification cost COST, calculating the amount of chemical oxygen demand COD required for unit denitrification, and calculating the denitrification rate DNR is the same as that in Embodiment 4, and will not be repeated;

[0144] In addition, the COD value of the external carbon source after the reaction EFF CODThe highest weight is 5 points, the lowest is 2 points, and the smallest COD value in the water after the reaction is ranked from small to large. The smallest COD value in the water after the reaction is U, and the weight value of U is 5 points. The largest value is J, and the weight value of J is 2 points. The weight scores of the COD values ​​in the water after the reaction of other external carbon sources are calculated according to the following formula:

[0145] q EFFCOD =5-(EFF COD -U)*(5-2) / (JU)

[0146] e) The total nitrogen TN value EFF in the water after the reaction of the external carbon source involved in the evaluation TN The highest weight is 5 points, the lowest is 2 points, and the smallest TN value in the water after the reaction is ranked from small to large. The smallest TN value in the water after the reaction is X, and the weight value of X is 5 points. The largest value is Y, and the weight value of Y is 2 points. The weight scores of the TN values ​​of the water after the reaction of other external carbon sources are calculated according to the following formula:

[0147] q EFFTN =5-(EFF TN -X)*(5-2) / (YX)

[0148] The weights of the above five indicators of each external carbon source are added together, and then sorted. The one with a higher comprehensive score is the better carbon source.

[0149] The results of external carbon source A, external carbon source B, and external carbon source C are:

[0150] External carbon source A: 24.6

[0151] External carbon source B: 32.3

[0152] External carbon source C: 28.3

[0153] Control bottle: 30.0

[0154] It can be seen that the external carbon source B is the better external carbon source.

[0155] Example 5: A method for using a device for screening external carbon sources for sewage treatment, using the device in Example 1, the method adopts the following steps, and the detection and inspection methods used in the claims are all commonly known methods in the industry and are not described in detail:

[0156] 1) Preparation of test materials:

[0157] a) Use the muddy water at the end of the normal operating sewage treatment anoxic tank as the bottom mud, measure the amount of mixed suspended volatile solids, the content of denitrifying bacteria, pH value, and temperature in the bottom mud, and adjust them to the normal value of the anoxic tank for normal denitrification reaction. The adjustment range is: mixed suspended volatile solids: 50%-70%, denitrifying bacteria content: 5%-25%, pH value: 6-8, temperature: 15-30℃;

[0158] b) Determine the nitrate concentration in the sediment. When the nitrate content of the sediment is lower than 20 mg / L, add potassium nitrate solution to make the nitrate content F of the sediment reach 30 mg / L for standby use;

[0159] c) preparing an external carbon source solution: taking a solid external carbon source powder with a powder fineness of 200 mesh, or an external carbon source solution, dissolving the powder in purified water to a concentration of 30 g / L, and diluting the original external carbon source solution with purified water to a concentration of 5 g / L; this embodiment uses two external carbon source solutions provided by a certain enterprise, temporarily named external carbon source A and external carbon source B;

[0160] d) Prepare comparative conical flasks and auxiliary devices of the same specifications;

[0161] 2) Specific screening experimental steps:

[0162] a) Take 3 liters of sediment and pour them into the flasks respectively, so that the liquid level is level with the highest scale line of the flask; take the external carbon source solution prepared in step 1), the concentration of the external carbon source solution in the sediment is 4 times the concentration F, calculate the amount of external carbon source and volume V required to be added based on the volume of the bottom mud in the triangular bottle 外碳源 ; and record the V of the added external carbon source 外碳源 , in order to calculate the cost; the above three types of substances constitute the experimental mixed solution, the volume of the mixed solution is set to V, V = the maximum scale value of the conical flask + V 外碳源 ;

[0163] b) Place the flask on the tray of the magnetic stirrer, put in the magnetic rotor, adjust the speed of the magnetic rotor to 300-500 rpm, and adjust the speed to produce a small vortex during stirring but without gas inhalation to prevent the entry of oxygen; insert the long needle of the syringe on the stopper of the flask into the position 5 cm below the liquid surface in the flask, keep the lower end of the hard tube at 3 cm above the liquid surface in the flask, and immerse the other end of the hose in a beaker containing distilled water for exhausting nitrogen;

[0164] c) Stirring sampling: Sampling is performed once every 0.5 hours, and sampling can be performed 4 times, with a total reaction time of 2 hours. After each reaction time, the mixed solution is allowed to settle in the conical flask for 10 minutes, and 10 mL of supernatant is taken once. During each sampling, the long needle does not move, and the syringe can be replaced after the sampling is completed; the supernatant is filtered with a 0.45 micron filter membrane, and then the nitrate concentration of each supernatant is determined respectively;

[0165] d) Calculate and test the denitrification effect of the external carbon source: Calculate the denitrification rate of the external carbon source according to the concentration of nitrate in the sediment after the reaction measured each time, and record it; the detection method of nitrate concentration and the calculation method of denitrification rate are conventional known methods;

[0166] e) performing steps a) to d) of the above method once for each external carbon source to be tested, and recording the results respectively; and performing the same test once using a control flask and auxiliary device with an equal amount of distilled water added but without the external carbon source solution, and recording the results;

[0167] f) Calculate the actual denitrification efficiency of the external carbon source: subtract the denitrification efficiency of each external carbon source added in the above steps from the denitrification efficiency of the control triangular flask without the external carbon source added, and obtain the denitrification efficiency value actually generated by the external carbon source;

[0168] g) Determine the cost performance of the external carbon source: Calculate the cost price of the external carbon source according to the amount of net external carbon source contained in the external carbon source solution obtained in each external carbon source test, which is a comprehensive cost including procurement, storage, transportation and processing costs; and the actual denitrification efficiency value of the external carbon source, which is calculated by dividing the last denitrification rate obtained in the previous step by the total cost price as the unit denitrification cost of the external carbon source;

[0169] h) Cost-effectiveness list of external carbon sources: a cost-effectiveness list of several external carbon sources, arranged from high to low in terms of cost-effectiveness, with the high-quality external carbon sources having the highest cost-effectiveness being high-quality external carbon sources, and thus the required high-quality external carbon sources with low cost and high denitrification rate can be screened out;

[0170] i) Prepare a denitrification rate list: Arrange the denitrification rates detected in the supernatant of each external carbon source in order of the time of removal. The one with the fastest denitrification rate is a high-quality external carbon source with a high denitrification rate. The external carbon source with a high denitrification rate can be selected. The more ideal external carbon source can be screened out by comprehensively considering the denitrification rate cost-effectiveness and denitrification rate.

[0171] The test results of the two external carbon sources in this embodiment are as follows:

[0172] Changes in nitrate concentration in the control bottle, external carbon source A, and external carbon source B over reaction time

[0173]

[0174] It can be seen from Table 1 that the effect of carbon source B is more obvious than that of carbon source A, indicating that carbon source B has better performance.

[0175] The external carbon source with good cost performance selected in the above embodiment has achieved good results in actual sewage treatment implementation. After multiple actual external carbon source screenings, the device and screening method of the present invention are effective and have stable effects.

[0176] The above description of the embodiments is to facilitate the understanding and application of the present invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the embodiments herein, and the technical solutions of improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. A method for using a device for screening external carbon sources for sewage treatment, characterized in that: The sewage treatment external carbon source screening device is provided with a triangular flask (1), a bottle stopper (2), a syringe with a long needle (3), a hose (4), a hard tube (5), a magnetic rotor (6), a magnetic stirrer (7) and a beaker (8); the bottle mouth of the triangular flask is provided with a bottle stopper; the mixed solution consisting of the external carbon source, muddy water at the end of the anoxic tank, i.e., bottom mud, and nitrate is contained in the triangular flask; the bottle stopper is provided with a needle hole for the long needle of the syringe to pass through and a mounting hole for the hard tube to pass through; the syringe with the long needle is installed on the needle hole; the hard tube is passed through the mounting hole, the upper end of which is connected to the hose, and the lower section is located in the triangular flask; one end of the hose is installed on the upper end of the hard tube; the other end of the hose is inserted into the pure water in the beaker; the beaker contains pure water of a preset height; the magnetic rotor is arranged at the bottom of the triangular flask; the triangular flask is arranged on the magnetic stirrer, and the magnetic rotor and the magnetic stirrer are connected to each other through the magnetic rotor and the magnetic stirrer. The stirrers cooperate with each other to stir the mixed liquid in the triangular flask; the volume of the triangular flask is 0.5L-5L, and the lower end of the hard tube is 2-4cm higher than the liquid level of the mixed liquid in the triangular flask; the length of the long needle is 15-30cm, and the lower end of the long needle is inserted below the liquid level of the mixed liquid, and the upper end of the long needle is connected to the lower end of the syringe body, so that the long needle can be used to take the reaction liquid in the triangular flask multiple times without taking it out; a needle sealing ring matching the shape of the needle hole is also provided on the needle head of the long needle; a hard tube sealing ring matching the shape of the hard tube mounting hole is also provided on the hard tube; the needle sealing ring and the hose sealing ring are both truncated cone-shaped sealing rings with an isosceles trapezoidal longitudinal section; an annular reinforcement ring is embedded in the outer peripheral surface of the truncated cone-shaped sealing ring; the annular reinforcement ring is an elastic steel ring, the outer wall of the sealing ring is tightly sealed with the bottle cap, and the inner wall is tightly sealed with the long needle and the hard tube respectively; The method for using the sewage treatment external carbon source screening device is characterized in that the method comprises the following steps, and the detection methods that are not described in detail in the following steps are all existing well-known methods and will not be described in detail: 1) Preparation of test materials: a) The muddy water at the end of the anoxic pool is used as the bottom mud, and the mixed suspended solid concentration MLSS, chemical oxygen demand COD, and total nitrogen TN of the bottom mud are measured and calculated as D TN0 , Nitrate nitrogen The concentration is D 硝0 , place the bottom mud in a cool place at 10-25℃ for later use; b) prepare potassium nitrate standard solution, the concentration of potassium nitrate standard solution is 1-2g / L, and keep it for future use; c) preparing an external carbon source solution: taking a solid external carbon source powder or a solution external carbon source, the powder needs to be dissolved in purified water, and the chemical oxygen demand COD is used as a characterization index. The chemical oxygen demand COD of the external carbon source on the market is generally 20-100 g / L; diluting the external carbon source to a chemical oxygen demand COD concentration of 10-20 g / L according to the COD index of the external carbon source product, and leaving it for use in step 2); d) When monitoring nitrate nitrogen in sediment When the concentration is lower than 20 mg / L, add potassium nitrate standard solution to the sediment until the nitrate concentration is The concentration F reaches 20-40 mg / L; at this time, the TN concentration in the sediment is calculated as D TN前 =D TN0 -D 硝0 +F; 2) Specific experimental steps: a) Take 2-10L of the sludge prepared in the previous step, and take the volume of the selected flask as the basis. The volume of the sludge is the sum of the volume of the flask multiplied by the number of carbon sources to be detected plus 1; b) Adding materials: Take a conical flask and add the sediment liquid level in step a) after shaking to the maximum scale of the conical flask; add the external carbon source solution prepared above to the conical flask respectively, and the concentration of the external carbon source solution in the sediment is 1:

1. - 3-N concentration F is 4-6 times, and the amount of external carbon source and volume V to be added are calculated based on the volume of the bottom mud in the triangular bottle. 外碳源 ; and record the V of the added external carbon source 外碳源 , in order to calculate the cost; the above three types of substances constitute the experimental mixed solution, the volume of the mixed solution is set to V, V = the maximum scale value of the conical flask + V 外碳源 ; c) Keep another comparative flask and add the same amount of sediment and potassium nitrate standard solution as in step b), without adding an external carbon source, but add the same amount of distilled water as the external carbon source in the other flasks, as a blank control; d) Place the flask on the tray of the magnetic stirrer, put in the magnetic rotor, adjust the speed of the magnetic rotor to 300-500rpm, and adjust the speed to produce a small vortex during stirring but without gas inhalation to prevent oxygen from entering; insert a 15-30cm long needle into one of the two holes of the flask mouth 4-6cm below the water surface, and the lower end of the hard tube is 2-4cm above the liquid surface in the flask, and the other end of the hose is immersed in a beaker containing distilled water to exhaust nitrogen; e) Stirring sampling: Sampling is done once every 0.25-1 hour, and sampling can be done 1-6 times. The total reaction time is H. After each reaction time, let it settle for 5-10 minutes before sampling. Take 10-15mL of supernatant each time, filter it with a 0.45 micron filter membrane, and determine the chemical oxygen demand COD and total nitrogen TN of the supernatant after the reaction. When sampling each time, the long needle does not move, and the syringe can be replaced after the sampling is completed. The chemical oxygen demand COD value of the supernatant measured by the last sampling is set as EFF COD , the total nitrogen TN value is set as EFF TN ; f) The above steps are performed once for each external carbon source to be tested, and the results are recorded; the control flask is also operated once, and the results are recorded; g) Establish a method for evaluating the performance of external carbon sources, calculate the nitrogen removal cost COST according to the cost of removing one unit of total nitrogen, and the one with the lower unit nitrogen removal cost COST is the better external carbon source; The total nitrogen TN value of the mixed solution in the blank triangular flask after the reaction is calculated as EFF TN空白 , the total nitrogen removal after the reaction is completed is set as M 空白 , M 空白 =(TN 前 -EFF TN空白 )*V; The cost of adding the external carbon source in the triangular flask is set as D, and the total nitrogen TN value after the reaction is calculated as EFF TN The amount of total nitrogen TN removed from the flask containing the external carbon source solution is set as M S , M S =(TN 前 -EFF TN )*V; The actual amount of total nitrogen removed by the external carbon source solution is △TN M S -M 空白 ,This part takes into account the contribution of sediment to the removal of total nitrogen, and can more scientifically judge the contribution of external carbon sources to the removal of total nitrogen; Unit denitrification cost COST = D / △TN.

2. The method for using the device for screening external carbon sources for sewage treatment according to claim 1, characterized in that: Establish a method for judging the performance of external carbon sources, calculate the unit denitrification cost COST and the amount of chemical oxygen demand COD required for unit denitrification as Q, calculate the weighted scores respectively, add the two together, and the one with the higher comprehensive score is the better external carbon source; a) Unit denitrification cost COST = D / △TN, the weight value of this indicator is q COST The highest score is 10 and the lowest score is 5. The unit nitrogen removal cost COST of the external carbon sources participating in the evaluation is sorted from small to large. The one with the smallest unit nitrogen removal cost COST is set to M, and the weight value of M is 10 points. The one with the largest unit nitrogen removal cost COST is set to K, and the weight value of K is 5 points. The unit nitrogen removal cost COST weight scores of the remaining external carbon sources are calculated according to the following formula: The weight value q of the unit nitrogen removal cost COST of a certain external carbon source COST =10-(COST-M)*(10-5) / (KM) b) In the experiment, △COD is set as the chemical oxygen demand COD of the added external carbon source; The amount of chemical oxygen demand (COD) required for unit denitrification is set as Q, Q = △COD / △TN, and the weight value of this indicator is q q The highest score can be 10 points, and the lowest score can be 5 points; The amount Q of chemical oxygen demand (COD) required for unit denitrification of the external carbon sources participating in the evaluation is sorted from small to large. The one with the smallest amount Q of chemical oxygen demand (COD) required for unit denitrification is set as P, and the weight value of P is 10 points. The largest one is set as S, and the weight value of S is 5 points. The weight scores of the amount Q of chemical oxygen demand (COD) required for unit denitrification of the remaining external carbon sources are calculated according to the following formula: q q =10-(Q-P)*(10-5) / (S-P) The above two weight indicators of each external carbon source are added together and then sorted. The one with a higher comprehensive score is the better carbon source.

3. The method for using the device for screening external carbon sources for sewage treatment according to claim 1, characterized in that: Establish a method for evaluating the performance of external carbon sources, calculate the unit nitrogen removal cost COST, the amount of chemical oxygen demand COD required for unit nitrogen removal, and the denitrification rate DNR, and calculate the weighted scores respectively. The three are added together, and the one with the highest comprehensive score is the better external carbon source; a) Unit denitrification cost COST = D / △TN, the weight value of this indicator is q COST The highest score is 10 and the lowest score is 5. The unit nitrogen removal cost COST of the external carbon sources participating in the evaluation is sorted from small to large. The one with the smallest unit nitrogen removal cost COST is set to M, and the weight value of M is 10 points. The one with the largest unit nitrogen removal cost COST is set to K, and the weight value of K is 5 points. The unit nitrogen removal cost COST weight scores of the remaining external carbon sources are calculated according to the following formula: The weight value q of the unit nitrogen removal cost COST of a certain external carbon source COST =10-(COST-M)*(10-5) / (KM) b) In the experiment, △COD is set as the chemical oxygen demand COD of the added external carbon source; The amount of chemical oxygen demand (COD) required for unit denitrification is set as Q, Q = △COD / △TN, and the weight value of this indicator is q q The highest score can be 10 points, and the lowest score can be 5 points; The amount Q of chemical oxygen demand (COD) required for unit denitrification of the external carbon sources participating in the evaluation is sorted from small to large. The one with the smallest amount Q of chemical oxygen demand (COD) required for unit denitrification is set as P, and the weight value of P is 10 points. The largest one is set as S, and the weight value of S is 5 points. The weight scores of the amount Q of chemical oxygen demand (COD) required for unit denitrification of the remaining external carbon sources are calculated according to the following formula: q q =10-(Q-P)*(10-5) / (S-P) c) Denitrification rate DNR = △TN / mixed suspended solid concentration MLSS / reaction time, where the reaction time is the total reaction time set to H, and the weight value of this indicator is set to q DNR ,q DNR The highest weight is set at 8 points and the lowest is set at 5 points; The denitrification rates DNR of the external carbon sources participating in the evaluation are sorted from small to large. The one with the smallest denitrification rate DNR is set as T, and the weight value of T is 5 points. The largest one is set as W, and the weight value of W is 8 points. The weight scores of the denitrification rates DNR of the remaining external carbon sources are calculated according to the following formula: q DNR =8-(W-DNR)*(8-5) / (W-T) The above three weight indicators of each external carbon source are added together and then sorted. The one with a higher comprehensive score is the better carbon source.

4. The method for using the device for screening external carbon sources for sewage treatment according to claim 1, characterized in that: Establish a method for evaluating the performance of external carbon sources, calculate the unit nitrogen removal cost COST, calculate the amount of chemical oxygen demand COD required for unit nitrogen removal, calculate the denitrification rate DNR, detect the chemical oxygen demand COD value in the water after the reaction, and detect the total nitrogen TN value in the water after the reaction, and calculate the weighted scores respectively. Add up the five, and the one with the highest comprehensive score is the better external carbon source; a) Unit denitrification cost COST = D / △TN, the weight value of this indicator is q COST The highest score is 10 and the lowest score is 5. The unit nitrogen removal cost COST of the external carbon sources participating in the evaluation is sorted from small to large. The one with the smallest unit nitrogen removal cost COST is set to M, and the weight value of M is 10 points. The one with the largest unit nitrogen removal cost COST is set to K, and the weight value of K is 5 points. The unit nitrogen removal cost COST weight scores of the remaining external carbon sources are calculated according to the following formula: The weight value q of the unit nitrogen removal cost COST of a certain external carbon source COST =10-(COST-M)*(10-5) / (KM) b) In the experiment, △COD is set as the chemical oxygen demand COD of the added external carbon source; The amount of chemical oxygen demand (COD) required for unit denitrification is set as Q, Q = △COD / △TN, and the weight value of this indicator is q q The highest score can be 10 points, and the lowest score can be 5 points; The amount Q of chemical oxygen demand (COD) required for unit denitrification of the external carbon sources participating in the evaluation is sorted from small to large. The one with the smallest amount Q of chemical oxygen demand (COD) required for unit denitrification is set as P, and the weight value of P is 10 points. The largest one is set as S, and the weight value of S is 5 points. The weight scores of the amount Q of chemical oxygen demand (COD) required for unit denitrification of the remaining external carbon sources are calculated according to the following formula: q q =10-(Q-P)*(10-5) / (S-P) c) Denitrification rate DNR = △TN / mixed suspended solids concentration MLSS / reaction time H, the weight value of this indicator is q DNR The highest score can be 8 points, and the lowest score can be 5 points; The denitrification rates DNR of the external carbon sources participating in the evaluation are sorted from small to large. The one with the smallest denitrification rate DNR is set as T, and the weight value of T is 5 points. The largest one is set as W, and the weight value of W is 8 points. The weight scores of the denitrification rates DNR of the remaining external carbon sources are calculated according to the following formula: q DNR =8-(W-DNR)*(8-5) / (W-T) d) The COD value of the water after the reaction of the external carbon source involved in the evaluation COD The highest weight is 5 points, the lowest is 2 points, and the smallest COD value in the water after the reaction is ranked from small to large. The smallest COD value in the water after the reaction is U, and the weight value of U is 5 points. The largest value is J, and the weight value of J is 2 points. The weight scores of the COD values ​​in the water after the reaction of other external carbon sources are calculated according to the following formula: q EFFCOD =5-(EFF COD -U)*(5-2) / (JU) e) The total nitrogen TN value EFF in the water after the reaction of the external carbon source involved in the evaluation TN The highest weight is 5 points, the lowest is 2 points, and the smallest TN value in the water after the reaction is ranked from small to large. The smallest TN value in the water after the reaction is X, and the weight value of X is 5 points. The largest value is Y, and the weight value of Y is 2 points. The weight scores of the TN values ​​of the water after the reaction of other external carbon sources are calculated according to the following formula: q EFFTN =5-(EFF TN -X)*(5-2) / (Y-X) The weights of the above five indicators of each external carbon source are added together, and then sorted. The one with a higher comprehensive score is the better carbon source.

5. The method for using the device for screening external carbon sources for sewage treatment according to claim 1, characterized in that The following steps are included. The detection and inspection methods used in the claims are commonly known methods in the industry and will not be described in detail: 1) Preparation of test materials: a) Use the muddy water at the end of the normal operating sewage treatment anoxic tank as the bottom mud, measure the amount of mixed suspended volatile solids, the content of denitrifying bacteria, pH value, and temperature in the bottom mud, and adjust them to the normal value of the anoxic tank for normal denitrification reaction. The adjustment range is: mixed suspended volatile solids: 50%-70%, denitrifying bacteria content: 5%-25%, pH value: 6-8, temperature: 15-30℃; b) Determine the nitrate concentration in the sediment. When the nitrate content of the sediment is lower than 20 mg / L, add potassium nitrate solution to make the nitrate content F of the sediment reach 20-40 mg / L for standby use; c) preparing an external carbon source solution: taking a solid external carbon source powder with a powder fineness of 200-300 mesh, or an external carbon source solution, dissolving the powder in purified water to a concentration of 20-40 g / L, and diluting the original external carbon source solution with purified water to a concentration of 10-20 g / L; d) Prepare comparative conical flasks and auxiliary devices of the same specifications; 2) Specific screening experimental steps: a) Take 3 liters of sediment and pour them into the flasks respectively, so that the liquid level is level with the highest scale line of the flask; take the external carbon source solution prepared in step 1), the concentration of the external carbon source solution in the sediment is 4-6 times the concentration F, calculate the amount of external carbon source and volume V required to be added based on the volume of the bottom mud in the triangular bottle 外碳源 ; and record the V of the added external carbon source 外碳源 , in order to calculate the cost; the above three types of substances constitute the experimental mixed solution, the volume of the mixed solution is set to V, V = the maximum scale value of the conical flask + V 外碳源 ; b) placing a conical flask on the tray of a magnetic stirrer, inserting a magnetic rotor, adjusting the speed of the magnetic rotor to 300-500 rpm, and adjusting the speed to produce a small vortex during stirring but without gas inhalation to prevent the entry of oxygen; inserting the long needle of the syringe on the conical flask stopper 4-6 cm below the liquid surface in the conical flask, keeping the lower end of the hard tube 2-4 cm above the liquid surface in the conical flask, and immersing the other end of the hose in a beaker containing distilled water for exhausting nitrogen; c) Stirring sampling: Sampling is performed once every 0.25-1 hour, and sampling can be performed 1-6 times, with a total reaction time of 2-4 hours. After each reaction time, the mixed solution is allowed to settle in the conical flask for 5-10 minutes, and 10-15 mL of supernatant is taken. During each sampling, the long needle does not move, and the syringe can be replaced after the sampling is completed; the supernatant is filtered with a 0.45 micron filter membrane, and then the nitrate concentration of each supernatant is measured respectively; d) Calculate and test the denitrification effect of the external carbon source: Calculate the denitrification rate of the external carbon source according to the concentration of nitrate in the sediment after the reaction measured each time, and record it; the detection method of nitrate concentration and the calculation method of denitrification rate are conventional known methods; e) performing steps a) to d) of the above method once for each external carbon source to be tested, and recording the results respectively; and performing the same test once using a control flask and auxiliary device with an equal amount of distilled water added but without the external carbon source solution, and recording the results; f) Calculate the actual denitrification efficiency of the external carbon source: subtract the denitrification efficiency of each external carbon source added in the above steps from the denitrification efficiency of the control triangular flask without the external carbon source added, and obtain the denitrification efficiency value actually generated by the external carbon source; g) Determine the cost performance of the external carbon source: Calculate the cost price of the external carbon source according to the amount of net external carbon source contained in the external carbon source solution obtained in each external carbon source test, which is a comprehensive cost including procurement, storage, transportation and processing costs; and the actual denitrification efficiency value of the external carbon source, which is calculated by dividing the last denitrification rate obtained in the previous step by the total cost price as the unit denitrification cost of the external carbon source; h) Cost-effectiveness list of external carbon sources: a cost-effectiveness list of several external carbon sources, arranged from high to low in terms of cost-effectiveness, with the high-quality external carbon sources having the highest cost-effectiveness being high-quality external carbon sources, and thus the required high-quality external carbon sources with low cost and high denitrification rate can be screened out; i) Prepare a denitrification rate list: Arrange the denitrification rates detected in the supernatant of each external carbon source in order of the time of removal. The one with the fastest denitrification rate is a high-quality external carbon source with a high denitrification rate. The external carbon source with a high denitrification rate can be selected. The more ideal external carbon source can be screened out by comprehensively considering the denitrification rate cost-effectiveness and denitrification rate.

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