A method for rapidly determining organic matter in sludge

Abstract

The application discloses a kind of methods for rapidly determining sludge organic matter, specifically comprising the following steps: step one: preparation reagent and material;Step two: preparation experimental instrument;Step three: sample collection and pretreatment;Step four: first, the instrument is debugged, after debugging, calibration curve is drawn, finally, sample is analyzed;Step five: total organic carbon concentration is calculated using difference subtraction and direct method;Step six: finally, the precision and accuracy of experiment are calculated.The method for determining sludge organic matter provided by the application using total organic carbon analyzer has by the sample together with the purified gas is respectively introduced into high-temperature combustion tube and low-temperature reaction tube, the sample in high-temperature combustion tube is high-temperature catalytic oxidation, the organic carbon and inorganic carbon therein are all converted into carbon dioxide, the sample in low-temperature reaction tube is acidified, and the total carbon and inorganic carbon of the sample can be quantitatively determined, effectively improving the stability and accuracy of detection.

Description

Technical Field

[0001] This invention relates to the field of organic matter content determination technology in sludge, and more particularly to a rapid method for determining organic matter in sludge. Background Technology

[0002] Sludge is a byproduct of wastewater treatment in wastewater treatment plants. It contains abundant organic matter and can create an excellent environment for plant growth and soil improvement. Land application of sludge is considered one of the most economical and valuable sludge treatment methods currently available.

[0003] In the land application of sewage sludge, organic matter and nutrient content are important influencing factors. Organic matter can effectively improve soil structure and chemical composition, enhance soil coefficients and buffering capacity, enrich soil microbial diversity, and optimize the soil microbial environment. Therefore, determining the organic matter content in sewage sludge is of significant guiding importance for the land application of sewage sludge and soil improvement.

[0004] Currently, there is no standard method for sludge determination in China. The determination of sludge organic matter often draws on the method for determining soil organic matter. However, the existing technology has the following shortcomings: the organic matter content of sludge is relatively high, the existing methods have a limited scope of application, and when detecting the absorbance of the solution, the suspended matter after sludge digestion has an interactive effect on the spectrum, affecting its stability and accuracy. Summary of the Invention

[0005] This invention discloses a method for rapidly determining organic matter in sludge, aiming to solve the technical problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A rapid method for determining organic matter in sludge includes the following steps:

[0008] Step 1: Prepare reagents and materials;

[0009] Step Two: Prepare the experimental equipment;

[0010] Step 3: Sample collection and pretreatment;

[0011] Step 4: First, debug the instrument, then plot the calibration curve, and finally analyze the sample;

[0012] Step 5: Calculate the total organic carbon concentration using the difference method and the direct method;

[0013] Step Six: Finally, calculate the precision and accuracy of the experiment;

[0014] The reagents and materials in step one include carbon dioxide-free water, hydrochloric acid, hydrochloric acid solution, phosphoric acid, phosphoric acid solution, anhydrous glucose, anhydrous sodium carbonate, and carrier gas. The carbon dioxide-free water is prepared by boiling and evaporating redistilled water in a beaker (evaporation rate 10%), cooling it, and then using it for later use, or by using pure water or ultrapure water prepared by a water purifier. The carbon dioxide-free water should be prepared fresh before use and tested to ensure that the TOC concentration does not exceed 0.5 mg / L.

[0015] In a preferred embodiment, a 2 mol / L hydrochloric acid solution is prepared by measuring 170 mL of hydrochloric acid and diluting it to 1000 mL with water. The anhydrous glucose needs to be dried at 75°C for 1 hour and cooled in a desiccator before use. The anhydrous sodium carbonate is of analytical grade and is a primary standard reagent, dried at 105°C for 1 hour and cooled in a desiccator before use. The carrier gas is oxygen with a purity greater than 99.99%. The experimental instruments in step two include glassware, a total organic carbon analyzer, a vacuum freeze dryer, an analytical balance, a sample boat, a soil sieve, and commonly used laboratory instruments and equipment. The sample boat is made of porcelain, quartz, or platinum, and is available in various sizes. Sample boats made of tin and nickel cannot be used in contact with acid. The soil sieve is made of stainless steel.

[0016] In a preferred embodiment, step three specifically includes the following steps: placing the sludge sample in a clean white enamel tray and spreading it into a thin layer of 2cm to 3cm; first removing the remains of plants, insects, and stones; crushing the mud lumps with a wooden mallet; and air-drying it naturally, turning it over several times a day during the air-drying process; mixing the air-dried mud sample thoroughly; using the quartering method, taking two portions, keeping one portion and passing the other through a 2mm soil sieve; freeze-drying the other portion for 24 hours using a freeze dryer; taking 10g to 20g of the freeze-dried sample for further fine grinding and passing it through a 60-mesh (0.25mm) soil sieve.

[0017] In a preferred embodiment, step four, the plotting of the difference calibration curve, includes the following steps: Accurately weighed 0.0 mg, 5.0 mg, 10.0 mg, 20.0 mg, 40.0 mg, and 60.0 mg of glucose are added to a set of six sample boats, respectively, to prepare a standard series with total carbon contents of 0.0 mg, 2.0 mg, 4.0 mg, 8.0 mg, 16.0 mg, and 24.0 mg. The response values ​​are measured according to the steps, and the total carbon calibration curve is plotted by corresponding the instrument response values ​​to the standard series contents; Accurately weighed 0.0 mg, 21.2 mg, 42.4 mg, 63.6 mg, 106.0 mg, and 212.0 mg of glucose are added to a set of six sample boats, respectively. Sodium carbonate was used to prepare a standard series with inorganic carbon contents of 0.0 mg, 2.4 mg, 4.8 mg, 7.2 mg, 10.0 mg, and 20.0 mg. The response values ​​were measured according to the steps outlined. An inorganic carbon calibration curve was plotted by mapping the standard series contents to the instrument response values. Step four, the direct method calibration curve plotting, included the following steps: Accurately weighed 0.0 mg, 5.0 mg, 10.0 mg, 20.0 mg, 40.0 mg, and 60.0 mg of glucose were added to a set of six sample boats, respectively, to prepare a standard series with organic carbon contents of 0.0 mg, 2.0 mg, 4.0 mg, 8.0 mg, 16.0 mg, and 24.0 mg. The response values ​​were measured according to the steps outlined. An organic carbon calibration curve was plotted by mapping the standard series contents to the instrument response values. The concentration range of the calibration curve could be adjusted according to the instrument and the type of sample being measured.

[0018] In a preferred embodiment, the difference method in step five specifically includes the following steps: weighing 0.002g to 0.005g of air-dried, sieved and dried sludge, placing it in a sample boat, pushing the sample boat into a high-temperature combustion furnace according to the instrument's prompts, recording the corresponding response value, thereby obtaining the total carbon peak area of ​​the sample;

[0019] Weigh 0.002g to 0.005g of the air-dried, sieved, and dried sludge again and place it in the sample boat. Acidify the sample with phosphoric acid. Following the instrument prompts, pass the sample into a combustion tube heated to 200℃ and record the corresponding response value to obtain the inorganic carbon peak area of ​​the sample. The direct method in step five specifically includes the following steps: Weigh 0.002g to 0.005g of the air-dried, sieved, and dried sludge and place it in the sample boat. Add an appropriate amount of hydrochloric acid. After the reaction is complete, push the sample boat into the high-temperature combustion furnace according to the instrument prompts and record the corresponding response value to obtain the organic carbon peak area of ​​the sample. Following the steps described in the sample, replace the sample boat with an empty sample boat and determine its response value according to the steps.

[0020] As can be seen from the above, a rapid method for determining the organic matter in sludge specifically includes the following steps:

[0021] Step 1: Prepare reagents and materials; Step 2: Prepare experimental instruments; Step 3: Sample collection and pretreatment; Step 4: First, debug the instrument, then plot the calibration curve, and finally analyze the sample; Step 5: Calculate the total organic carbon concentration using the difference method and the direct method; Step 6: Finally, calculate the precision and accuracy of the experiment. The method for determining sludge organic matter using a total organic carbon analyzer provided by this invention involves passing the sample along with purified gas into a high-temperature combustion tube and a low-temperature reaction tube, respectively. The sample in the high-temperature combustion tube is catalytically oxidized at high temperature, converting both organic and inorganic carbon into carbon dioxide. The sample in the low-temperature reaction tube is acidified, decomposing the inorganic carbon into carbon dioxide. The carbon dioxide generated in both reaction tubes is introduced into a non-dispersive infrared detector. At a specific wavelength, the infrared absorption intensity of carbon dioxide within a certain range is proportional to its concentration. Therefore, the total carbon and inorganic carbon in the sample can be quantitatively determined, effectively improving the stability and accuracy of the detection. Attached Figure Description

[0022] Figure 1 This is a graph showing the unified sample test results of the method for rapid determination of organic matter in sludge proposed in this invention.

[0023] Figure 2 This is a graph showing the organic matter spike recovery rate test results of a rapid method for determining organic matter in sludge proposed in this invention. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0025] Reference Figure 1 and Figure 2 A method for determining organic matter in urban sewage sludge using a total organic carbon analyzer, specifically including the following steps:

[0026] Step 1: Prepare reagents and materials;

[0027] Step Two: Prepare the experimental equipment;

[0028] Step 3: Sample collection and pretreatment;

[0029] Step 4: First, debug the instrument, then plot the calibration curve, and finally analyze the sample;

[0030] Step 5: Calculate the total organic carbon concentration using the difference method and the direct method;

[0031] Step Six: Finally, calculate the precision and accuracy of the experiment;

[0032] The reagents and materials for step one include carbon dioxide-free water, hydrochloric acid, hydrochloric acid solution, phosphoric acid, phosphoric acid solution, anhydrous glucose, wastewater sodium carbonate, and carrier gas. Carbon dioxide-free water: boil redistilled water in a beaker to evaporate (evaporation rate 10%), cool and set aside, or use pure water or ultrapure water prepared by a water purifier. Carbon dioxide-free water should be prepared fresh before use and tested to ensure that the TOC concentration does not exceed 0.5 mg / L.

[0033] In a preferred embodiment, a 2 mol / L hydrochloric acid solution is prepared, and 170 mL of hydrochloric acid water is measured and diluted to 1000 mL. Anhydrous glucose needs to be dried at 75°C for 1 hour and cooled in a desiccator before use. Anhydrous sodium carbonate is of analytical grade and is a primary standard reagent. It is dried at 105°C for 1 hour and cooled in a desiccator before use. The carrier gas is oxygen with a purity greater than 99.99%.

[0034] In a preferred embodiment, the experimental instruments in step two include glassware, a total organic carbon analyzer, a vacuum freeze dryer, an analytical balance, a sample boat, a soil sieve, and commonly used laboratory instruments and equipment. The sample boat is made of porcelain, quartz, or platinum, and is available in various sizes. Sample boats made of tin and nickel cannot be used in contact with acid, and the soil sieve is made of stainless steel.

[0035] In a preferred embodiment, step three specifically includes the following steps: placing the sludge sample in a clean white enamel tray and spreading it into a thin layer of 2cm to 3cm, first removing the remains of plants, insects, and stones, crushing the mud blocks with a wooden mallet, and air-drying it naturally. During air-drying, turn it over several times a day, mix the air-dried mud sample evenly, and use the quartering method to take two portions, one of which is kept and the other is passed through a 2mm soil sieve. Freeze-dry the sample using a freeze dryer for 24 hours, and take out 10g to 20g of the freeze-dried sample for further fine grinding and passing it through a 60-mesh (0.25mm) soil sieve.

[0036] In a preferred embodiment, step four, the plotting of the subtraction calibration curve, includes the following steps: In a set of six sample boats, accurately weighed amounts of 0.0 mg, 5.0 mg, 10.0 mg, 20.0 mg, 40.0 mg, and 60.0 mg of glucose are added respectively to prepare a standard series with total carbon contents of 0.0 mg, 2.0 mg, 4.0 mg, 8.0 mg, 16.0 mg, and 24.0 mg. The response values ​​are measured according to the steps, and the total carbon calibration curve is plotted by corresponding the instrument response values ​​to the standard series contents. In another set of six sample boats, accurately weighed amounts of 0.0 mg, 21.2 mg, 42.4 mg, 63.6 mg, 106.0 mg, and 212.0 mg of sodium carbonate are added respectively to prepare a standard series with inorganic carbon contents of 0.0 mg, 2.4 mg, 4.8 mg, 7.2 mg, 10.0 mg, and 20.0 mg. The response values ​​are measured according to the steps, and the inorganic carbon calibration curve is plotted by corresponding the instrument response values ​​to the standard series contents.

[0037] In a preferred embodiment, step four, the plotting of the direct method calibration curve, includes the following steps: Accurately weighed amounts of 0.0 mg, 5.0 mg, 10.0 mg, 20.0 mg, 40.0 mg, and 60.0 mg of glucose are added to a set of six sample boats, respectively, to prepare a standard series with organic carbon contents of 0.0 mg, 2.0 mg, 4.0 mg, 8.0 mg, 16.0 mg, and 24.0 mg. The response values ​​are then measured according to the steps. An organic carbon calibration curve is plotted using the standard series contents corresponding to the instrument response values. The concentration range of the calibration curve can be adjusted according to the instrument and the type of sample being measured.

[0038] In a preferred embodiment, the difference method in step five specifically includes the following steps: weighing 0.002 to 0.005 g of air-dried, sieved and dried sludge, placing it in the sample boat, pushing the sample boat into the high-temperature combustion furnace according to the instrument prompts, recording the corresponding response value, thereby obtaining the total carbon peak area of ​​the sample.

[0039] Weigh 0.002g to 0.005g of the air-dried, sieved and dried sludge again, put it into the sample boat, acidify the sample with phosphoric acid, and pass it into the combustion tube heated to 200℃ according to the instrument prompts, record the corresponding response value, and thus obtain the inorganic carbon peak area of ​​the sample.

[0040] In a preferred embodiment, the direct method in step five specifically includes the following steps: weighing 0.002 g to 0.005 g of air-dried, sieved and dried sludge, placing it in a sample boat, adding an appropriate amount of hydrochloric acid, waiting for the reaction to be complete, pushing the sample boat into a high-temperature combustion furnace according to the instrument prompts, recording the corresponding response value, thereby obtaining the sample organic carbon peak area, and measuring its response value by replacing the sample with an empty sample boat according to the sample steps.

[0041] In a preferred embodiment, the difference subtraction method is used for calculation:

[0042] Based on the response value of the tested sample, the total carbon and inorganic carbon concentrations were calculated from the calibration curve. The total organic carbon concentration in the sample was:

[0043] TOC=TC-IC................................................(1)

[0044] In the formula:

[0045] TOC—Total organic carbon concentration of the sample, expressed as a percentage.

[0046] TC—Total carbon concentration of the sample, expressed as a percentage;

[0047] IC—Inorganic carbon concentration of the sample, expressed as a percentage;

[0048] Direct method: The total organic carbon (TOC) concentration is calculated from the calibration curve based on the response value of the tested sample, and expressed as a percentage.

[0049] The value of organic matter in sludge, expressed as a percentage, is calculated according to formula (2):

[0050] Organic matter (%) = TOC × 1.724..........................................(2)

[0051] In the formula:

[0052] TOC—Total organic carbon concentration of the sample, expressed as a percentage.

[0053] 1.724 — the coefficient for converting organic carbon to organic matter.

[0054] Precision and accuracy: Three laboratories conducted measurements on two uniform samples with different concentrations. The intra-laboratory relative standard deviation (RSD) for sample 1, with an average measured value of 52.4%, was 1.15%–1.65%, and the intra-laboratory RSD for sample 2, with an average measured value of 42.2%, was 1.08%–4.90%. The sample spike recovery rate ranged from 91.2% to 106.6%.

[0055] Precautions: The amount of hydrochloric acid added depends on the sample mass and carbonate content. In all cases, hydrochloric acid should be added in excess to completely remove carbonates from the sample.

[0056] After each sample analysis, the sample boat must be cleaned with hydrochloric acid, with the principle that the instrument baseline should no longer show peaks.

[0057] In a preferred embodiment, the present invention is based on the principle of determining organic matter in wastewater by combustion oxidation-non-dispersive infrared absorption method. The total organic carbon in the sludge is measured and then multiplied by the Vanbemmelen factor of 1.724 to convert organic carbon into organic matter.

[0058] In a preferred embodiment, three laboratories measured the organic matter content of uniform samples at 52.4% and 42.2%, respectively. The intra-laboratory relative standard deviations were 1.15%–1.65% and 1.08%–4.90%, respectively; the inter-laboratory relative standard deviations were 9.39% and 11.4%, respectively; and the spiked recoveries ranged from 93.5% to 108% and 91.2% to 106%, respectively.

[0059] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for rapid determination of organic matter in sludge, characterized in that, Specifically, the following steps are included: Step 1: Prepare reagents and materials; Step Two: Prepare the experimental equipment; Step 3: Sample collection and pretreatment; Step 4: First, debug the instrument, then plot the calibration curve, and finally analyze the sample; Step 5: Calculate the total organic carbon concentration using the difference method and the direct method; Step Six: Finally, calculate the precision and accuracy of the experiment; The reagents and materials in step one include carbon dioxide-free water, hydrochloric acid, hydrochloric acid solution, phosphoric acid, phosphoric acid solution, anhydrous glucose, anhydrous sodium carbonate, and carrier gas. The carbon dioxide-free water is prepared by boiling and evaporating redistilled water in a beaker (evaporation rate 10%), cooling it, and then using it for later use, or by using pure water or ultrapure water prepared by a water purifier. The carbon dioxide-free water should be prepared fresh before use and tested to ensure that the TOC concentration does not exceed 0.5 mg / L. The experimental instruments in step two include glassware, a total organic carbon analyzer, a vacuum freeze dryer, an analytical balance, a sample boat, a soil sieve, and other commonly used laboratory instruments and equipment. The sample boat is made of porcelain, quartz, or platinum, and is available in various sizes. Sample boats made of tin and nickel cannot be used in contact with acids. The soil sieve is made of stainless steel. Step three specifically includes the following steps: Place the sludge sample in a clean white enamel tray, spread it into a thin layer of 2cm to 3cm, remove any plant, insect, or stone debris, crush the sludge lumps with a wooden mallet, and allow it to air dry naturally. During air drying, turn the sample several times a day to ensure thorough mixing. The air-dried mud sample was divided into two parts using the quartering method. One part was retained, and the other part was passed through a 2mm soil sieve and freeze-dried for 24 hours. 10g-20g of the freeze-dried sample was then further ground and passed through a 60-mesh soil sieve. Step four, the plotting of the difference calibration curve, includes the following steps: Accurately weighed 0.0mg, 5.0mg, 10.0mg, 20.0mg, 40.0mg, and 60.0mg of glucose were added to a set of six sample boats, respectively, to prepare samples with total carbon contents of 0.0mg, 2.0mg, 4.0mg, 8.0mg, and 16.0mg. A standard series of 0.0 mg and 24.0 mg sodium carbonate was prepared, and its response values ​​were determined according to the procedure. The total carbon calibration curve was plotted by mapping the standard series content to the instrument response values. In a set of six sample boats, accurately weighed sodium carbonate of 0.0 mg, 21.2 mg, 42.4 mg, 63.6 mg, 106.0 mg, and 212.0 mg was added to prepare a standard series with inorganic carbon contents of 0.0 mg, 2.4 mg, 4.8 mg, 7.2 mg, 10.0 mg, and 20.0 mg, respectively. The response values ​​were determined according to the procedure. The inorganic carbon calibration curve was plotted by mapping the standard series content to the instrument response values. In step four, the plotting of the direct method calibration curve includes the following steps: In a set of six sample boats, accurately weighed 0.0 mg, 5.0 mg, 10.0 mg, 20.0 mg, 40.0 mg, and 60.0 mg of glucose are added respectively to prepare a standard series with organic carbon contents of 0.0 mg, 2.0 mg, 4.0 mg, 8.0 mg, 16.0 mg, and 24.0 mg. The response values ​​are measured according to the steps, and the organic carbon calibration curve is plotted by corresponding the instrument response values ​​to the standard series contents. The concentration range of the calibration curve can be adjusted according to the instrument and the type of sample being measured.

2. The method for rapid determination of organic matter in sludge according to claim 1, characterized in that, To prepare a 2 mol / L hydrochloric acid solution, measure 170 mL of hydrochloric acid and dilute to 1000 mL with water. The anhydrous glucose needs to be dried at 75°C for 1 hour and cooled in a desiccator before use. The anhydrous sodium carbonate is of analytical grade and is a primary standard reagent. It is dried at 105°C for 1 hour and cooled in a desiccator before use. The carrier gas is oxygen with a purity greater than 99.99%.

3. The method for rapid determination of organic matter in sludge according to claim 1, characterized in that, The difference method in step five specifically includes the following steps: weigh the air-dried, sieved and dried sludge, put it into the sample boat, push the sample boat into the high-temperature combustion furnace according to the instrument prompts, record the corresponding response value, and thus obtain the total carbon peak area of ​​the sample. Weigh the air-dried, sieved, and dried sludge again and place it in the sample boat. Acidify the sample with phosphoric acid and, following the instrument prompts, pass it into a combustion tube heated to 200°C. Record the corresponding response values ​​to obtain the inorganic carbon peak area of ​​the sample.

4. The method for rapid determination of organic matter in sludge according to claim 3, characterized in that, The direct method in step five specifically includes the following steps: weigh the air-dried, sieved and dried sludge, put it into the sample boat, add an appropriate amount of hydrochloric acid, wait for the reaction to be complete, push the sample boat into the high-temperature combustion furnace according to the instrument prompts, record the corresponding response value, and thus obtain the sample organic carbon peak area. According to the steps described in the sample, replace the sample with an empty sample boat and determine its response value according to the steps.

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