A method for determining the optimal dosage of dewatering flocculant in river silt

Abstract

This invention provides a method for determining the optimal dosage of dewatering flocculant in river silt, belonging to the field of silt treatment technology. The invention first removes large impurities from the river silt and stirs it to obtain pretreated silt. Then, samples of the pretreated silt are taken, and the sand content of the samples is measured. Finally, the measured sand content is substituted into a fitted formula relating the sand content to the optimal dosage of dewatering flocculant to calculate the optimal dosage of dewatering flocculant required for treating the river silt. This invention only requires consideration of the river silt particle size distribution, primarily based on the sand content, to determine the optimal dosage of flocculant during vacuum dewatering. The determination method is simple and easy to implement, facilitating the resource utilization of silt.

Description

Technical Field

[0001] This invention relates to the field of river and lake silt treatment technology, and in particular to a method for determining the optimal amount of dewatering flocculant added to river silt. Background Technology

[0002] In the overall process of river dredging, flocculation and dewatering technology for sludge is a crucial and significant step. The core principle of flocculation and dewatering is to add flocculants to the sludge, causing fine suspended particles to aggregate into larger agglomerates, which are then separated into solid and liquid phases using mechanical or physical methods. This treatment method not only effectively reduces the volume of sludge, thereby lowering transportation and disposal costs, but also lays a solid foundation for the resource utilization of sludge. In actual sludge treatment, the appropriate addition of flocculants can significantly reduce the water content of the sludge, further reducing its volume and creating favorable conditions for subsequent dewatering and resource utilization.

[0003] However, determining the appropriate flocculant dosage is a complex technical challenge. Due to the complex and variable composition of sludge, determining the flocculant dosage involves not only core technical issues of water treatment and sludge dewatering, but also requires comprehensive analysis of various factors, including intelligent control and optimization, economic efficiency, and environmental benefits. Currently, determining the flocculant dosage typically relies on empirical methods or simple quantitative models to simplify the decision-making process. However, these methods often suffer from significant instability, easily leading to excessive or insufficient flocculant dosage. This not only increases the cost of chemical agents but also affects the effectiveness and economics of sludge treatment, limiting overall treatment efficiency.

[0004] Therefore, it is very important to provide a method for determining the optimal dosage of a stable dehydrating flocculant. Summary of the Invention

[0005] The purpose of this invention is to provide a method for determining the optimal amount of dewatering flocculant added to river silt, thereby solving the technical problem that the methods in the prior art are unstable, resulting in excessive or insufficient addition of dewatering flocculant.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for determining the optimal dosage of dewatering flocculant in river silt, comprising the following steps:

[0008] (1) Pretreatment: Remove large impurities from the river silt and stir to obtain pretreated silt;

[0009] (2) Take samples of the pretreated sludge and determine the sand content of the sludge in the samples;

[0010] (3) Substitute the measured silt and sand content into the fitted formula for the relationship between silt and sand content and the optimal dosage of dewatering flocculant to calculate the optimal dosage of dewatering flocculant required to treat river silt.

[0011] The relationship between the silt and sand content x and the optimal amount of flocculant y is: y = 0.366 - 0.072ln(x).

[0012] Furthermore, the sand content of the river silt is 10-40%, the powder-to-viscosity ratio of the river silt is 3.5-4:1, and the initial water content of the river silt is 45-55%.

[0013] Furthermore, the method for determining the silt sand content is either direct determination or sieving.

[0014] Furthermore, the dehydrating flocculant includes anionic polyacrylamide.

[0015] Furthermore, the molecular weight of the dehydrating flocculant is 1500w to 2000w.

[0016] Furthermore, the concentration of the dehydrating flocculant is 1–5 g / L.

[0017] Furthermore, the amount of dehydrating flocculant added is the mass ratio of the dry powder of the dehydrating flocculant to the dry silt of the river channel.

[0018] The beneficial effects of this invention are:

[0019] (1) The determination method of the present invention only requires determining the optimal amount of dewatering flocculant added during the vacuum dewatering process of silt based on the particle size distribution of river silt and the sand content of silt. The determination method is simple and easy to implement, which provides convenience for the resource utilization of silt.

[0020] (2) The determination method of the present invention takes into account the large difference in particle size distribution between upstream and downstream of river silt, and improves the dewatering scheme for river silt, which facilitates the implementation of the flocculation and dewatering process of river and lake bottom sediment in actual engineering.

[0021] (3) The determination method of the present invention has good stability and can effectively avoid the situation of adding too much flocculant in actual engineering. It can effectively solve the problem of high water content and slow dewatering speed of river silt, effectively improve the dewatering efficiency of silt, provide convenience for the resource utilization of silt, and has good economic and social benefits. Attached Figure Description

[0022] Figure 1 This is a flowchart of the sludge dewatering method for determining the amount of flocculant to be added based on sludge particle size according to the present invention.

[0023] Figure 2This is a fitted curve showing the relationship between the silt and sand content and the optimal addition amount of dewatering flocculant in this invention.

[0024] Figure 3 The graph shows the specific resistance of sludge with a sand content of 10% versus the moisture content of the sludge cake after filtration under different amounts of dewatering flocculant.

[0025] Figure 4 The graph shows the specific resistivity of sludge with a sand content of 20% versus the moisture content of the sludge cake after filtration under different amounts of dewatering flocculant.

[0026] Figure 5 The graph shows the specific resistivity of sludge with a sand content of 30% versus the moisture content of the sludge cake after filtration under different amounts of dewatering flocculant.

[0027] Figure 6 The graph shows the specific resistance of sludge with a sand content of 40% versus the moisture content of the sludge cake after filtration under different amounts of dewatering flocculant. Detailed Implementation

[0028] This invention provides a method for determining the optimal dosage of dewatering flocculant in river silt, comprising the following steps:

[0029] (1) Pretreatment: Remove large impurities from the river silt and stir to obtain pretreated silt;

[0030] (2) Take samples of the pretreated sludge and determine the sand content of the sludge in the samples;

[0031] (3) Substitute the measured silt and sand content into the fitted formula for the relationship between silt and sand content and the optimal dosage of dewatering flocculant to calculate the optimal dosage of dewatering flocculant required to treat river silt.

[0032] The relationship between the silt and sand content x and the optimal amount of flocculant y is: y = 0.366 - 0.072ln(x).

[0033] In this invention, the sand content of the river silt is 10-40%, preferably 15-35%, and more preferably 20-30%; the powder-to-viscosity ratio of the river silt is 3.5-4:1, preferably, and more preferably; the initial water content of the river silt is 45-55%, preferably 47-53%, and more preferably 50%.

[0034] In this invention, the method for determining the silt sand content is either direct determination or sieving, preferably sieving.

[0035] In this invention, the method for directly determining the sand content of silt is as follows: the particle size distribution of the sample is directly determined by using a laser particle size analyzer to obtain the sand content of the target silt.

[0036] In this invention, the method for determining the sand content of silt by sieving is as follows: after drying the target silt at 105°C, it is sieved according to the Chinese standard "Standard for Geotechnical Testing Methods" BG / T50123-1999, and then its sand content is determined.

[0037] In this invention, the dehydrating flocculant is preferably anionic polyacrylamide.

[0038] In this invention, the molecular weight of the dehydrating flocculant is 1500w to 2000w, preferably 1600w to 1900w, and more preferably 1700w to 1800w.

[0039] In this invention, the concentration of the dehydrating flocculant is 1-5 g / L, preferably 1.5-4 g / L, and more preferably 2-3 g / L.

[0040] In this invention, the amount of dehydrating flocculant added is the mass ratio of the dry powder of the dehydrating flocculant to the dry silt of the river channel, and the unit is dimensionless.

[0041] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0042] The silt with different particle sizes used in the embodiments of the present invention is prepared from raw silt by wet sieving. The raw silt meets the following conditions: initial particle size distribution is: sand content 20.12%, silt content 62%, clay content 17.27%; initial moisture content is 55%.

[0043] The dehydrating flocculant used in this embodiment of the invention is anionic polyacrylamide (APAM) with a molecular weight of 1800w and a concentration of 2g / L. The dehydrating flocculant is prepared by stirring 1g APAM in 500mL of distilled water for 45min. The APAM solution is viscous and homogeneous.

[0044] In practical engineering, the specific resistance is 9×10 10 Sludge with a density below cm / g has a strong dewatering capacity, therefore 9×10 10 The region below cm / g is considered easily dehydrated. In this embodiment of the invention, 9×10⁻⁶ cm / g is used. 10 The optimal amount of flocculant to be added is determined using cm / g as a reference.

[0045] Example 1

[0046] The sludge in Example 1 was prepared by wet sieving of the original sludge, and the particle size distribution was: 10% sand content, 71.39% powder content, and 18.61% clay content, that is, sludge with a sand content of 10% and a powder-to-clay ratio of 3.84:1.

[0047] 100g of sludge and water were mixed with anionic polyacrylamide flocculant at concentrations of 0%, 0.05%, 0.08%, 0.1%, 0.12%, 0.15%, 0.2%, and 0.25% of the dry sludge weight, respectively, to prepare a flocculated slurry with a solid content of 10%. After uniform stirring for 1 minute, the slurry was poured into a resistivity meter and vacuum filtered at 0.05 MPa for 20 minutes or until the sludge cake ruptured. The resistivity value was calculated, and the moisture content of the slurry cake was measured. The test results are as follows: Figure 3 As shown.

[0048] Figure 3 This is a graph showing the specific resistivity of sludge with a sand content of 10% versus the moisture content of the sludge cake after filtration under different amounts of dewatering flocculant. From... Figure 3 It can be seen that when the amount of anionic polyacrylamide added is 0.2%, the specific resistivity decreases to 9.95 × 10⁻⁶. 10 cm / g, close to 9×10 10 The area with a water content of cm / g is easily dehydrated, and the moisture content of the mud cake reaches a minimum of 50.75%. Therefore, the optimal addition amount of dewatering flocculant is 0.20% under vacuum filtration of sludge with a sand content of 10%.

[0049] Example 2

[0050] The sludge in Example 2 was prepared by adding water to the original sludge to obtain sludge with a sand content of 20% and a powder-to-viscosity ratio of 3.59:1.

[0051] 100g of sludge and water were mixed with anionic polyacrylamide flocculant at concentrations of 0%, 0.05%, 0.08%, 0.1%, 0.12%, 0.15%, 0.2%, and 0.25% of the dry sludge weight, respectively, to prepare a flocculated slurry with a solid content of 10%. After uniform stirring for 1 minute, the slurry was poured into a resistivity meter and vacuum filtered at 0.05 MPa for 20 minutes or until the sludge cake ruptured. The resistivity value was calculated, and the moisture content of the slurry cake was measured. The test results are as follows: Figure 4 As shown.

[0052] Figure 4 This is a graph showing the specific resistivity of sludge with a sand content of 20% versus the moisture content of the sludge cake after filtration under different amounts of dewatering flocculant. Figure 4 It can be seen that when the amount of anionic polyacrylamide added is 0.15%, the specific resistivity decreases to 10.59 × 10⁻⁶. 10 cm / g, close to 9×10 10 The area with a sand content of 20% is easily dehydrated (cm / g), and the moisture content of the mud cake reaches a minimum of 52.33%. Therefore, the optimal addition amount of dewatering flocculant is 0.15% under vacuum filtration of sludge with a sand content of 20%.

[0053] Example 3

[0054] The sludge in Example 3 was prepared by wet sieving of the original sludge, and the particle size distribution was: 30% sand, 55.2% powder, and 14.8% clay, that is, sludge with a sand content of 30% and a powder-to-clay ratio of 3.72:1.

[0055] 100g of sludge and water were mixed with anionic polyacrylamide flocculant at concentrations of 0%, 0.05%, 0.08%, 0.1%, 0.12%, 0.15%, 0.2%, and 0.25% of the dry sludge weight, respectively, to prepare a flocculated slurry with a solid content of 10%. After uniform stirring for 1 minute, the slurry was poured into a resistivity meter and vacuum filtered at 0.05 MPa for 20 minutes or until the sludge cake ruptured. The resistivity value was calculated, and the moisture content of the slurry cake was measured. The test results are as follows: Figure 5 As shown.

[0056] Figure 5 This is a graph showing the specific resistivity of sludge with a sand content of 30% versus the moisture content of the sludge cake after filtration under different amounts of dewatering flocculant. From... Figure 5 It can be seen that when the amount of anionic polyacrylamide added is 0.12%, the specific resistivity decreases to 11.01 × 10⁻⁶. 10 cm / g, close to 9×10 10 The area with a sand content of 30% is easily dehydrated (cm / g), and the moisture content of the mud cake reaches a minimum of 53.33%. Therefore, the optimal addition amount of dewatering flocculant is 0.15% under vacuum filtration conditions.

[0057] Example 4

[0058] The sludge in Example 4 was prepared by wet sieving of the original sludge, with a particle size distribution of 40% sand, 47.3% powder, and 12.7% clay, i.e., sludge with a sand content of 40% and a powder-to-clay ratio of 3.72:1.

[0059] 100g of sludge and water were mixed with anionic polyacrylamide flocculant at concentrations of 0%, 0.05%, 0.08%, 0.1%, 0.12%, 0.15%, 0.2%, and 0.25% of the dry sludge weight, respectively, to prepare a flocculated slurry with a solid content of 10%. After uniform stirring for 1 minute, the slurry was poured into a resistivity meter and vacuum filtered at 0.05 MPa for 20 minutes or until the sludge cake ruptured. The resistivity value was calculated, and the moisture content of the slurry cake was measured. The test results are as follows: Figure 6 As shown.

[0060] Figure 6 This is a graph showing the specific resistivity of sludge with a sand content of 40% versus the moisture content of the sludge cake after filtration under different amounts of dewatering flocculant. From... Figure 6It can be seen that when the amount of anionic polyacrylamide added is 0.10%, the specific resistivity decreases to 12.24 × 10⁻⁶. 10 cm / g, which is close to 9×10 10 In the easily dewatered zone (cm / g), and with the minimum moisture content of the sludge cake reaching 55.77%, when the amount of anionic polyacrylamide added is 0.12%, the specific resistance is below the easily dewatered zone, but the moisture content of the sludge cake increases, and the increase is relatively large. Therefore, it is not considered to be the optimal addition amount. Thus, when the amount of dewatering flocculant added is 0.15%, it is the optimal addition amount for vacuum filtration of sludge with a sand content of 40%.

[0061] As can be seen from the above embodiments, the present invention provides a method for determining the optimal dosage of dewatering flocculant in river silt. First, large impurities are removed from the river silt and the silt is stirred to obtain pretreated silt. Then, samples of the pretreated silt are taken, and the sand content of the samples is measured. Finally, the measured sand content is substituted into the fitted relationship between the sand content and the optimal dosage of dewatering flocculant to calculate the optimal dosage of dewatering flocculant required to treat the river silt. The present invention only requires determining the optimal dosage of flocculant during the vacuum dewatering process of the silt based on the particle size distribution of the river silt, mainly according to the sand content. The determination method is simple and easy to implement, providing convenience for the resource utilization of silt.

[0062] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for determining the optimal dosage of dewatering flocculant in river silt, characterized in that, Includes the following steps: (1) Pretreatment: Remove large impurities from the river silt and stir to obtain pretreated silt; (2) Take samples of the pretreated sludge and determine the sand content of the sludge in the samples; (3) Substitute the measured silt and sand content into the fitted formula for the relationship between silt and sand content and the optimal dosage of dewatering flocculant to calculate the optimal dosage of dewatering flocculant required to treat river silt. The relationship between the silt and sand content x and the optimal amount of flocculant y is: y = 0.366 - 0.072ln(x).

2. The method for determining the optimal amount of dewatering flocculant added to river silt according to claim 1, characterized in that, The river silt has a sand content of 10-40%, a silt-to-viscosity ratio of 3.5-4:1, and an initial water content of 45-55%.

3. The method for determining the optimal amount of dewatering flocculant added to river silt according to claim 1 or 2, characterized in that, The method for determining the silt sand content is either direct determination or sieving.

4. The method for determining the optimal amount of dewatering flocculant added to river silt according to claim 3, characterized in that, The dehydrating flocculant includes anionic polyacrylamide.

5. The method for determining the optimal amount of dewatering flocculant added to river silt according to claim 4, characterized in that, The molecular weight of the dehydrating flocculant is 1500-2000w.

6. The method for determining the optimal amount of dewatering flocculant added to river silt according to claim 4 or 5, characterized in that, The concentration of the dehydrating flocculant is 1–5 g / L.

7. The method for determining the optimal amount of dewatering flocculant added to river silt according to claim 6, characterized in that, The amount of dehydrating flocculant added is the mass ratio of the dry powder of the dehydrating flocculant to the dry silt in the river channel.

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