Method for detecting silt content and particle size distribution of primary sludge
Through ultrasonic cleaning, distilled water rinsing, PAM flocculation and microporous filter suction filtration, the problem of inaccuracy and low efficiency of sewage treatment plants when measuring the particle size distribution of initial sewage sludge sludge is solved, and high accuracy and Fast test results.
Patent Information
- Application Number
- CN202411585039.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-07
- Publication Date
- 2024-12-20
AI Technical Summary
It is difficult for existing sewage treatment plants to accurately measure the particle size distribution of sludge and the detection efficiency is low, resulting in increased processing difficulty and equipment wear.
The initial sediment sludge sample was processed by an ultrasonic cleaning machine, combined with distilled water rinsing and centrifuge separation, flocculation was performed using PAM, and then suction filtered through a microporous filter membrane and dried in a drying chamber, and finally burned in a muffle furnace for accurate results. granularity distribution data.
Accurate detection of the distribution of sludge and sand particle size in the initial sediment sludge is achieved, which reduces the detection time and sample plate setting problems, and improves the accuracy and repeatability of the measurement results.
Smart Images
Figure CN119164843A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of primary sludge sand content detection, and in particular to a method for detecting the sand content and particle size distribution of primary sludge. Background Art
[0002] In urban sewage treatment, due to factors such as urban construction and development, imperfect drainage network, topography and climate, the mud and sand content in sewage has increased significantly. This problem is particularly prominent in mountainous cities and newly developed urban areas.
[0003] The grit chambers of existing sewage treatment plants are only designed to remove sand with a particle size greater than 200μm, while a large amount of fine sand (less than 200μm) is deposited in the primary sedimentation tank. The accumulation of such fine sand not only increases the difficulty of primary sludge treatment, reduces the sludge digestion efficiency and sludge incineration calorific value, but also brings wear and blockage risks to subsequent treatment equipment. Therefore, sewage treatment plants need to understand the content of sand in primary sludge and its particle size distribution in order to take corresponding measures.
[0004] At present, dry screening, wet screening and laser particle size are mainly used, combined with high temperature burning and other means to remove organic matter in primary sludge to determine the amount of sand and particle size distribution of primary sludge, as follows:
[0005] 1. Dry screening method: After the primary sludge sample is dried and burned, it is screened with a sieve to measure the amount of mud and sand and the particle size distribution. Since the primary sludge contains a large amount of clay (<2μm), the clay may undergo physical structure changes due to the loss of crystal water or adsorbed water during the burning process, and the particles may shrink and deform, which is very easy to produce adhesion; at the same time, burning will also change the chemical properties of the clay surface, and the static electricity or van der Waals force will adhere to each other at high temperature. After burning, the sample becomes compacted, and small particles of mud and sand adhere and aggregate, resulting in inaccurate measurement results;
[0006] 2. Wet screening method: first, the sieve is screened under the action of slow water flow, and then the sieve material and the sieve material are dried and burned separately, and then weighed separately. This method cannot effectively separate clay from organic matter, and there may still be compaction problems after burning; and when using the wet screening method, the volume of the dried sample increases and the drying time is long, resulting in the sewage treatment plant being unable to quickly obtain the particle size distribution of mud and sand, affecting the timely adjustment of the sewage treatment plant to production operations.
[0007] 3. Laser particle size measurement method: disperse the sample to be tested in a liquid medium and irradiate it with a laser beam. The light emitted by the laser passes through the sample. When the laser beam interacts with the particles, the particles scatter the light. Use a detector to receive the scattered light, and calculate the particle size distribution diagram and related statistical data by analyzing the intensity and angle of the scattered light. This method requires the removal of other compounds except silica, and only measures the particle size distribution of silica. Primary sludge contains not only silica, but also a large number of other inorganic compounds. Therefore, this method cannot accurately reflect the particle size distribution of mud and sand.
[0008] In summary, the above methods are difficult to accurately measure the particle size distribution of primary sludge sand; and the drying time is long and the detection efficiency is low. Therefore, a new method for measuring the sand content and particle size distribution in primary sludge is urgently needed to better meet the accurate measurement needs of places with high fine sand content such as mountainous cities and newly developed urban areas. Summary of the invention
[0009] The present invention aims to provide a method for detecting the sand content and particle size distribution of primary sludge, so as to solve the problems of inaccurate detection results and long detection time for the sand content and particle size distribution in primary sludge.
[0010] To achieve the above object, the present invention adopts the following technical scheme: a method for detecting the sand content and particle size distribution of primary sludge, comprising the following steps:
[0011] Step 1: Use a sampling bottle to collect 1000-2000 ml of primary sludge;
[0012] Step 2: Place the collected samples in an ultrasonic cleaning machine for ultrasonic oscillation treatment;
[0013] Step 3: Place the ultrasonically treated sample on the sieve with the minimum particle size to be tested, and rinse it repeatedly with distilled water until the mud and sand with a particle size smaller than the sieve hole is washed through the sieve, and collect the sieve-surface material and the sieve-underface material separately;
[0014] Step 4: Add 1-2 mg / L PAM to the beaker containing the sieve, let it stand for stratification, discard the supernatant, transfer and rinse the bottom mixture, and collect the rinse water together;
[0015] Step 5: Centrifuge the treated sieve material and sieve material at 8000r / min for 10min respectively, rinse the centrifuged samples with distilled water and place them in an evaporating dish;
[0016] Step 6: Place the evaporating dish in a drying oven and dry at 103°C to 105°C until constant weight;
[0017] Step 7: The dried oversize and undersize are burned separately at a burning temperature of 500-600°C, and then weighed. The burned oversize is sieved and weighed according to the set particle size to obtain the mass of mud and sand in the corresponding particle size range.
[0018] Preferably, step 5 can be replaced by directly filtering the sieve and the sieve after the treatment in step 4 with a 0.1 μm microporous ash-free filter membrane, respectively, so that the filtered samples are spread on the filter membrane, and then the filter membrane is cut into pieces and placed in an evaporating dish. Compared with traditional direct drying, the use of filter membranes to filter the sieve and the sieve can effectively reduce the water to be dried and disperse the samples as much as possible, greatly reducing the time required for the samples to be dried; because the samples are spread on the filter membrane during the filtration process, the samples are not only dispersed faster during burning, but also more helpful to reduce the burning time and reduce the compaction of the samples, greatly reducing the time for detecting the mud and sand content in the sludge, so that relevant personnel can obtain the test results in time to take corresponding measures.
[0019] Furthermore, in step 7, the filter membrane is first placed in a constant-weight porcelain crucible, and then placed in a muffle furnace for calcination. This makes it convenient to collect the mud and sand after calcination, because the weight of the porcelain crucible is constant, and it is also conducive to calculating the mass of the mud and sand after calcination.
[0020] Preferably, the fired porcelain crucible is placed in a dryer for drying before weighing in step 7. Organic matter decomposes and produces water during the firing process, which affects the quality of the fired mud and sand. Drying before weighing helps reduce the error in the quality of the mud and sand, making the test result more accurate.
[0021] Preferably, pressurized water is used to rinse the sample in step 3. Pressurized water rinsing and screening is more efficient and can penetrate into small gaps and hard-to-reach places, which is conducive to separating organic matter and mud and sand aggregates.
[0022] Preferably, in step 3, pressurized water is added along the tangent direction of the screen to rinse the sample. This allows the sample to swirl, effectively reducing screen blockage; and the sample is not easy to splash and lose, and subsequent test results are more accurate.
[0023] Preferably, in step 3, the sampling bottle in step 1 is used to collect the sieve material, and then 1-2 mg / L of PAM is added to the sampling bottle, the stratification is allowed to stand, the supernatant is discarded, the bottom mixture is transferred and rinsed, and the rinse water is collected together, and the volume of the mixture and the rinse water is less than 2000 ml. Part of the sample may remain in the sampling bottle after the sample is dumped. This solution collects the possible residual sample together in this way, reduces the sample loss, and makes the mud and sand content detection result of the sample more accurate.
[0024] Preferably, in step 7, the meshes with set particle sizes are placed on the vibrating screen in order of large to small diameters and from top to bottom for vibrating screening. In this way, the screening of mud and sand of various particle sizes can be performed simultaneously, the screening time can be reduced, and the speed of detecting the mud and sand content of the sample can be accelerated.
[0025] Preferably, the volume of the bottom mixture and the flushing water in step 4 is less than 2000 ml. The water content in the sample is reduced as much as possible, the processing time of the subsequent steps is reduced, and the detection speed is accelerated.
[0026] Preferably, the ultrasonic oscillation at 20kHz is performed for 15 to 20 minutes in step 2. The separation effect of clay and organic matter in the primary sludge sand is ensured as much as possible to avoid the problem of sample compaction after subsequent burning.
[0027] Beneficial effects of this program:
[0028] 1. Some clay and other large-grained mud and sand in the primary sludge form larger particles under the adhesion of organic matter, which are not easy to loosen under normal water flow. This scheme first uses ultrasonic oscillation to preliminarily separate small-grained clay, organic matter and large-grained mud and sand, and then uses the screen with the minimum particle size required to measure to filter the primary sludge sand washing. Since the clay particle size is smaller than the screen particle size, it will pass through the screen to achieve separation, enhancing the passing efficiency and screening efficiency of sand washing for small-grained clay; at the same time, the preliminarily separation of small-grained clay, organic matter and large-grained mud and sand is conducive to further separation of these substances during the flushing process, and all clay in the mud and sand should be separated as much as possible to avoid the problem of sample compaction after burning.
[0029] 2. In this scheme, PAM is used to flocculate the sieve material, which reduces the amount of centrifugal sample and shortens the detection time; PAM is an organic matter, and its volatilization after burning has no effect on the test results.
[0030] 3. Use a centrifuge to separate sand and water, reduce drying time, and further reduce the time for detecting the mud and sand content in the sludge, so that relevant personnel can obtain the test results in time and take corresponding measures.
[0031] 4. This method can realize accurate detection of mud and sand particle size distribution, solve the problem of sample compaction after burning, and has small measurement error and high repeatability. BRIEF DESCRIPTION OF THE DRAWINGS
[0032] Figure 1 Schematic diagram of a flow chart of an embodiment of the present invention.
[0033] Figure 2 This is a graph showing the test results of a standard sample (mainly composed of quartz sand) using a dry screening method, a wet screening method, a laser particle size method and the method of the present invention in an embodiment of the present invention.
[0034] Figure 3This is a diagram showing the measurement results of the same primary sludge sample using the method of the present invention. DETAILED DESCRIPTION
[0035] The following is further described in detail through specific implementation methods:
[0036] Example:
[0037] A method for detecting the sand content and particle size distribution of primary sludge, as shown in the attached Figure 1 As shown, the following steps are included:
[0038] Step 1: Use a sampling bottle to collect 1000-2000 ml of primary sludge.
[0039] In this step, 1000-2000 ml of primary sludge is directly collected using a sampling bottle, wherein the dry weight of mud and sand in the sample should be greater than 5 g, and the sampling bottle is sealed after the collection is completed. The collected samples need to be analyzed and measured as soon as possible, and if they need to be preserved, the samples need to be refrigerated at 0℃ to 4℃.
[0040] Step 2: Place the collected samples in an ultrasonic cleaning machine and oscillate at 20kHz for 15 to 20 minutes.
[0041] Some clay and other large-grained sand form larger particles under the adhesion of organic matter, which are not easy to loosen under normal water flow. Therefore, ultrasonic oscillation is first used to preliminarily separate small-grained clay, organic matter and large-grained sand to enhance the subsequent sand washing efficiency of small-grained clay.
[0042] Among them, the power of the ultrasonic cleaning machine is greater than 100w / L. It ensures the separation effect of clay and organic matter in the primary sludge and sand, and avoids the problem of sample compaction after subsequent burning.
[0043] Step 3: Place the ultrasonically treated sample on the sieve with the minimum particle size to be tested, and rinse it repeatedly with distilled water until the mud and sand smaller than the sieve size are washed through the sieve, and collect the sieve-surface material and the sieve-underface material separately.
[0044] In this step, the sample is placed on the sieve for washing and sieving in small quantities and multiple times. Gradual sieving can more accurately separate particles of different sizes and reduce the mixing of particles of different sizes; small batch processing reduces the burden on the sieve and reduces the risk of clogging and damage.
[0045] In this step, pressurized water is used to rinse the sample. Pressurized water sieving is more efficient and can penetrate into small gaps and hard-to-reach places, which is conducive to separating organic matter and mud and sand aggregates.
[0046] In this step, pressurized water is added along the tangent direction of the screen to rinse the sample. This allows the sample to swirl, effectively reducing screen blockage; and the sample is not easy to splash and lose, and subsequent test results are more accurate.
[0047] Use the sampling bottle in step 1 to collect the material on the sieve, then add 1-2 mg / L of PAM to the sampling bottle, let it stand for stratification, discard the supernatant, transfer and rinse the bottom mixture, and collect the rinse water together. The volume of the mixture and rinse water is less than 2000 ml. Some samples may remain in the sampling bottle after the sample is dumped. In this way, the remaining samples can be collected together to reduce the amount of sample loss, making the mud and sand content test results of the sample more accurate. (Rinse and recover the mud and sand samples that may remain in the sampling bottle in step 1)
[0048] Step 4: Add 1-2 mg / L PAM (polyacrylamide) to the beaker containing the sieve material, let it stand to separate the layers, discard the supernatant, transfer and rinse the bottom mixture, and collect the rinse water together. The volume of the mixture and the rinse water is less than 2000 ml.
[0049] Step 5: Centrifuge the processed material above the sieve and the material below the sieve at 8000 r / min for 10 min respectively. Rinse the centrifuged samples with distilled water and place them in an evaporating dish.
[0050] As an alternative, in this step, the mixture on the sieve and the screened mixture after being rinsed with distilled water can also be directly filtered using a 0.1 μm microporous ash-free filter membrane, respectively, so that the filtered samples are spread on the filter membrane, and then the filter membrane is cut into pieces and placed in an evaporating dish. In this embodiment, the above-mentioned filtration scheme is used as a supplementary treatment process of step 5, that is, the sample after being rinsed with distilled water in step 5 is filtered using a 0.1 μm microporous ash-free filter membrane, and the filter membrane with the sample after filtration is placed in an evaporating dish.
[0051] Step 6: Place the evaporating dish in a drying oven and dry it at 103℃~105℃ until constant weight.
[0052] Step 71: Place the dried oversize filter membrane and undersize filter membrane in a constant weight porcelain crucible respectively, and then place the porcelain crucible in a muffle furnace for calcination at a temperature of 500-600°C.
[0053] This makes it convenient to collect the mud and sand after burning, because the weight of the porcelain crucible is constant, and it is also helpful to calculate the mass of the mud and sand after burning.
[0054] Step 72: Place the fired porcelain crucible in a dryer for drying.
[0055] During the burning process, organic matter will decompose and produce water, which will affect the quality of the burned mud and sand. Drying before weighing can help reduce the error in mud and sand quality and make the test results more accurate.
[0056] Step 73: Screen the sieve material after burning according to the set particle size.
[0057] In this step, when screening the sieve material after burning, the sieves with set particle sizes are placed on the vibrating screen in order from large to small, from top to bottom, and then vibrated and screened. In this way, the screening of mud and sand of various particle sizes can be carried out simultaneously, which reduces the screening time and speeds up the detection of mud and sand content in the sample.
[0058] In this step, pour all the samples into the stacked 75-mesh (200 μm), 100-mesh (150 μm), 200-mesh (75 μm), and 300-mesh (50 μm) test sieves, and then perform manual sieving or place them on a vibrating sieve machine for vibration sieving. The sieving time is 20 to 30 minutes.
[0059] Step 74: Weigh the processed samples to obtain the mass of mud and sand in the corresponding particle size range.
[0060] The mass of the constant weight porcelain crucible is recorded as m 01 , burn and cool the porcelain crucible containing the sieve, then weigh it and record it as m 02 , the porcelain crucible containing the sieve material is burned and cooled, and then weighed and recorded as m, and the sieve materials of each level after burning are recorded as m1, m2...m i 、m i+1 .
[0061] The calculation formula of mud and sand volume is:
[0062]
[0063] Where, C is the amount of mud and sand (g / L); m0 is the mass of the constant weight crucible of the oversize (g); m is the mass of the sample after calcination in the constant weight crucible of the oversize (g); 01 —The mass of the constant weight crucible of the undersize (g); m 02 —The mass of the sample after calcination in the constant weight crucible of the undersize (g); v—the volume of the sample (L)
[0064] The formula for calculating the proportion of mud and sand that is smaller than the minimum sieve hole to the total mud and sand is:
[0065]
[0066] Where P is the proportion of mud and sand with a diameter smaller than the minimum sieve hole to the total mud and sand (%); m i —The mass of the material on the sieve after sieving the experimental sieve with the i-th aperture (g); m i+1—The mass of the sample in the bottom pan (g); m0—The mass of the constant weight crucible of the material on the sieve (g);
[0067] m—mass of the sample after calcination in the constant weight crucible containing the sieve (g); 01 —The mass of the constant weight crucible of the undersize (g); m 02 —The mass of the sample after calcination in the constant weight crucible containing the sieve underfill (g).
[0068] The formula for calculating the proportion of mud and sand with a diameter larger than a certain sieve hole to the total mud and sand is:
[0069]
[0070] Where P is the proportion of mud and sand with a diameter larger than a certain sieve hole to the total mud and sand (%); m i —mass of the material on the sieve after sieving the experimental sieve of the i-th aperture (g); m0—mass of the constant weight crucible of the material on the sieve (g); m—mass of the sample after calcination in the constant weight crucible of the material on the sieve (g); m 01 —The mass of the constant weight crucible of the undersize (g); m 02 —The mass of the sample after calcination in the constant weight crucible containing the sieve underfill (g).
[0071] In step 3 of this scheme, the sieve aperture is 300 mesh (50 μm), and the corresponding mud and sand particle size distribution results in the sludge can be calculated according to formulas (1), (2), and (3).
[0072] Attached Figure 2 The following is a graph showing the test results of a standard sample (mainly composed of quartz sand) using dry screening method, wet screening method, laser particle size method and the method of the present invention. Figure 2 It can be seen that for standard samples with a single component, both the dry screening method and the method of the present invention can achieve accurate detection of mud and sand particle size distribution.
[0073] Attached Figure 3 The following is a graph showing the results of the same primary sludge sample tested using the method of the present invention. Figure 3 It can be seen that the method of the present invention solves the problem of sample hardening after burning, has small measurement error and high repeatability.
[0074] This scheme first uses ultrasonic oscillation to preliminarily separate small-grained clay, organic matter and large-grained mud and sand, and then uses a screen with the minimum particle size required to be measured to filter the primary sludge sand washing. Since the clay particle size is smaller than the screen particle size, it will pass through the screen to achieve separation, thereby enhancing the passing efficiency and screening efficiency of the sand washing for small-grained clay; at the same time, the small-grained clay, organic matter and large-grained mud and sand are preliminarily separated, which is conducive to further separation of these substances during the flushing process, and all clay in the mud and sand is separated as much as possible to avoid the problem of sample compaction after burning; PAM organic matter is used to flocculate the sample , which greatly saves sedimentation time; PAM is an organic matter, and its volatilization after burning has no effect on the test results, and the test results of mud and sand content are more accurate; the use of a centrifuge to separate sand and water reduces the drying time, which greatly improves the detection speed of mud and sand content. In addition, the use of a filter membrane to filter out the sieve and the sieve can effectively reduce the amount of water to be dried and disperse the sample as much as possible compared to traditional direct drying, which greatly reduces the drying time and burning time required for the sample, and greatly reduces the detection time of mud and sand content in the sludge, so that relevant personnel can obtain the test results in a timely manner.
[0075] The above is only an embodiment of the present invention, and the common knowledge such as the known specific technical schemes and / or characteristics in the scheme is not described in detail here. It should be pointed out that for those skilled in the art, several variations and improvements can be made without departing from the technical scheme of the present invention. In the present invention, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fix" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal connection of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances. The scope of protection claimed in this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.
Claims
1. A method for detecting the sand content and particle size distribution of primary sludge, characterized in that: The following steps are involved: Step 1: Use a sampling bottle to collect 1000-2000 ml of primary sludge; Step 2: Place the collected samples in an ultrasonic cleaning machine for ultrasonic oscillation treatment; Step 3: Place the ultrasonically treated sample on the sieve with the minimum particle size to be tested, and rinse it repeatedly with distilled water until the mud and sand with a particle size smaller than the sieve hole is washed through the sieve, and collect the sieve-surface material and the sieve-underface material separately; Step 4: Add 1-2 mg / L PAM to the beaker containing the sieve, let it stand for stratification, discard the supernatant, transfer and rinse the bottom mixture, and collect the rinse water together; Step 5: Centrifuge the treated sieve material and sieve material at 8000r / min for 10min respectively, rinse the centrifuged samples with distilled water and place them in an evaporating dish; Step 6: Place the evaporating dish in a drying oven and dry at 103°C to 105°C until constant weight; Step 7: The dried oversize and undersize are burned separately at a burning temperature of 500-600°C, and then weighed. The burned oversize is sieved and weighed according to the set particle size to obtain the mass of mud and sand in the corresponding particle size range.
2. The method for detecting the sand content and particle size distribution of primary sludge according to claim 1, characterized in that: In the step 5, the treated sieve material and sieve material are directly filtered using a 0.1 μm microporous ash-free filter membrane, respectively, so that the filtered samples are spread on the filter membrane, and then the filter membrane is cut into pieces and placed in an evaporating dish.
3. The method for detecting the sand content and particle size distribution of primary sludge according to claim 1, characterized in that: In step 3, pressurized water is used to rinse the sample.
4. The method for detecting the sand content and particle size distribution of primary sludge according to claim 3, characterized in that: In step 3, pressurized water is added along the tangent direction of the sieve to rinse the sample.
5. The method for detecting the sand content and particle size distribution of primary sludge according to claim 1, characterized in that: In step 4, the sampling bottle in step 1 is used to collect the sieve material, and then 1-2 mg / L of PAM is added to the sampling bottle, and the stratification is allowed to stand, the supernatant is discarded, the bottom mixture is transferred and rinsed, and the rinse water is collected together. The volume of the bottom mixture and the rinse water is less than 2000 ml.
6. The method for detecting the sand content and particle size distribution of primary sludge according to claim 1, characterized in that: Step 7: Place the meshes with set particle sizes in order from large to small, and from top to bottom, overlapping each other on the vibrating screen for vibration screening.
7. The method for detecting the sand content and particle size distribution of primary sludge according to claim 2, characterized in that: In step 7, the filter membrane is first placed in a constant-weight porcelain crucible, and then placed in a muffle furnace for calcination.
8. The method for detecting the sand content and particle size distribution of primary sludge according to claim 7, characterized in that: In step 7, the fired porcelain crucible is placed in a dryer for drying and then weighed.
9. The method for detecting the sand content and particle size distribution of primary sludge according to claim 1, characterized in that: The volume of the bottom mixture and the flushing water in step 4 is less than 2000 ml.
10. The method for detecting the sand content and particle size distribution of primary sludge according to claim 1, characterized in that: In the step 2, 20 kHz ultrasonic oscillation is performed for 15 to 20 minutes.