Method for determining optimal addition amount of dewatering flocculant in river sludge

Abstract

The invention provides a method for determining the optimal addition amount of a dewatering flocculant in river sludge, and belongs to the technical field of sludge treatment. The method comprises the following steps: firstly, removing large impurities in the river silt, stirring to obtain pretreated silt, then sampling the pretreated silt, measuring the silt sand content of the sampled sample, and finally substituting the measured silt sand content into a relational expression between the silt sand content and the optimal dosage of the dewatering flocculant, which is obtained by fitting, so as to obtain the optimal dosage of the dewatering flocculant. And calculating the optimal addition amount of the dewatering flocculant required for treating the river sludge. According to the method, the optimal addition amount of the flocculating agent in the sludge vacuum dehydration process is determined only according to the particle size distribution of the river sludge and mainly according to the sand content, the judgment mode is simple and easy to implement, and convenience is provided for resource utilization of the sludge.

Description

Technical Field

[0001] The invention relates to the technical field of river and lake sludge treatment, and in particular to a method for determining the optimal addition amount of a dewatering flocculant in river sludge. Background Art

[0002] In the overall process of river dredging, sludge flocculation and dehydration technology is a crucial link and has significant significance. The core principle of flocculation and dehydration is to add flocculants to the sludge so that the fine suspended particles aggregate to form larger particle agglomerates, and then use mechanical or physical methods to achieve solid-liquid separation. This treatment method can not only effectively reduce the volume of sludge, thereby reducing the cost of transportation and disposal, but also lay a good foundation for the resource utilization of sludge. In the actual sludge treatment process, the reasonable addition of flocculants can greatly reduce the water content of sludge, further reduce its volume, and create favorable conditions for subsequent dehydration and resource utilization.

[0003] However, determining the appropriate amount of flocculant to be added is a complex technical challenge. Due to the complex and variable composition of sludge, the determination of the amount of flocculant to be added not only involves the core technical issues of water treatment and sludge dewatering, but also requires a comprehensive analysis of multiple factors, including intelligent control and optimization, economic and environmental benefits. At present, the method of determining the amount of flocculant to be added usually relies on empirical methods or simple quantitative models to simplify the decision-making process, but this method often has great instability and can easily lead to excessive or insufficient flocculant addition. This not only increases the cost of chemical agents, but also affects the effect and economy of sludge treatment, limiting the overall treatment efficiency.

[0004] Based on this, it is very important to provide a method for determining the optimal addition amount of a dehydration flocculant with good stability. Summary of the invention

[0005] The purpose of the present invention is to provide a method for determining the optimal addition amount of a dewatering flocculant in river sludge, so as to solve the technical problem that the method in the prior art is unstable, thereby causing excessive or insufficient addition of the dewatering flocculant.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for determining the optimal addition amount of a dewatering flocculant in river sludge, comprising the following steps:

[0008] (1) Pretreatment: removing large impurities from river sludge and stirring to obtain pretreated sludge;

[0009] (2) sampling the pretreated sludge and determining the sand content of the sampled sludge;

[0010] (3) Substituting the measured sludge sand content into the fitted relationship between the sludge sand content and the optimal dosage of the dewatering flocculant, the optimal amount of the dewatering flocculant required to treat the river sludge is calculated;

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

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

[0013] Furthermore, the silt sand content is determined by direct measurement or screening.

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

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

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

[0017] Furthermore, the added amount of the dewatering flocculant is the mass ratio of the dewatering flocculant dry powder to the river sludge dry mud.

[0018] Beneficial effects of the present invention:

[0019] (1) The determination method of the present invention only needs to determine the optimal amount of dewatering flocculant added during the sludge vacuum dewatering process according to the particle size distribution of the river sludge and the sand content of the sludge. The determination method is simple and easy, which provides convenience for the resource utilization of sludge;

[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 is convenient for carrying out the flocculation and dewatering process of river and lake sludge in actual engineering projects;

[0021] (3) The determination method of the present invention has good stability and can effectively avoid the situation where excessive flocculants are added in actual engineering projects. It can effectively solve the problems of high water content and slow dehydration speed of river sludge, effectively improve the sludge dehydration efficiency, provide convenience for the resource utilization of sludge, and have good economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a flow chart of the sludge dehydration method for determining the amount of flocculant added according to the sludge particle size of the present invention;

[0023] Figure 2The figure is a fitting curve diagram of the relationship between the content of sludge sand particles and the optimal addition amount of the dewatering flocculant of the present invention;

[0024] Figure 3 It is a graph of the specific resistance value of the sludge with a sand content of 10% and the moisture content of the mud cake after filtration at different addition amounts of dewatering flocculants;

[0025] Figure 4 This is a graph showing the specific resistance of sludge with a sand content of 20% and the moisture content of the mud cake after filtration at different addition amounts of dewatering flocculants;

[0026] Figure 5 The figure is the graph of the specific resistance value of the sludge with a sand content of 30% and the moisture content of the mud cake after filtration at different addition amounts of dewatering flocculant;

[0027] Figure 6 This is a graph showing the specific resistance of sludge with a sand content of 40% and the moisture content of the mud cake after filtration at different addition amounts of dewatering flocculant. DETAILED DESCRIPTION

[0028] The present invention provides a method for determining the optimal addition amount of a dewatering flocculant in river sludge, comprising the following steps:

[0029] (1) Pretreatment: removing large impurities from river sludge and stirring to obtain pretreated sludge;

[0030] (2) sampling the pretreated sludge and determining the sand content of the sampled sludge;

[0031] (3) Substituting the measured sludge sand content into the fitted relationship between the sludge sand content and the optimal dosage of the dewatering flocculant, the optimal amount of the dewatering flocculant required to treat the river sludge is calculated;

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

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

[0034] In the present invention, the method for determining the silt sand content is direct determination or screening method, preferably screening method.

[0035] In the present invention, the method for directly measuring the sand content of the sludge is: directly measuring the particle size distribution of the sample taken by a laser particle size analyzer to obtain the sand content of the target sludge.

[0036] In the present invention, the method for determining the sand content of sludge by sieving is: after drying the target sludge at 105°C, sieving it by sieving according to the provisions of China's "Geotechnical Test Method Standard" BG / T50123-1999 and then determining its sand content.

[0037] In the present invention, the dehydration flocculant is preferably anionic polyacrylamide.

[0038] In the present invention, the molecular weight of the dewatering flocculant is 1500w-2000w, preferably 1600w-1900w, and more preferably 1700w-1800w.

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

[0040] In the present invention, the added amount of the dewatering flocculant is the mass ratio of the dewatering flocculant dry powder to the river sludge dry mud, and the unit is dimensionless.

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

[0042] The sludge with different particle sizes used in the embodiment of the present invention is prepared from the original sludge by wet screening method, wherein the original sludge meets the following conditions: the initial particle size distribution is: sand content is 20.12%, powder content is 62%, clay content is 17.27%; the initial moisture content is 55%.

[0043] The dehydrating flocculant used in the embodiment of the present 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 distilled water for 45min, and the APAM solution is viscous and uniform.

[0044] In actual engineering, the specific resistance is 9×10 10 The dewatering capacity of sludge below cm / g is relatively strong, so 9×10 10 cm / g or less is the easy dehydration region. 10 cm / g is used as a reference to determine the optimal amount of flocculant added.

[0045] Example 1

[0046] The sludge in Example 1 is prepared from the original sludge by wet screening, and its particle size distribution is as follows: sand content 10%, powder content 71.39%, clay content 18.61%, that is, the sludge has 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 flocculants of 0%, 0.05%, 0.08%, 0.1%, 0.12%, 0.15%, 0.2% and 0.25% respectively to obtain flocculated mud with a solid content of 10%. After uniform stirring for 1 minute, the sludge was poured into a specific resistance instrument and vacuum filtered at 0.05MPa for 20 minutes or until the sludge cake broke. Calculate its specific resistance value and measure its cake moisture content. The test results are as follows: Figure 3 shown.

[0048] Figure 3 The figure shows the specific resistance value of sludge with a sand content of 10% and the moisture content of the mud cake after filtration at different addition amounts of dewatering flocculants. Figure 3 It can be seen that when the addition amount of anionic polyacrylamide is 0.2%, the specific resistance value is reduced to 9.95×10 10 cm / g, close to 9×10 10 cm / g is in the easy dehydration area, and the moisture content of the mud cake reaches the lowest value of 50.75%. Therefore, when the addition amount of the dehydration flocculant is 0.20%, it is the optimal addition amount under the vacuum filtration state of sludge with a sand content of 10%.

[0049] Example 2

[0050] The sludge in Example 2 is 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 flocculants of 0%, 0.05%, 0.08%, 0.1%, 0.12%, 0.15%, 0.2% and 0.25% respectively to obtain flocculated mud with a solid content of 10%. After uniform stirring for 1 minute, the sludge was poured into a specific resistance instrument and vacuum filtered at 0.05MPa for 20 minutes or until the sludge cake broke. Calculate its specific resistance value and measure its cake moisture content. The test results are as follows: Figure 4 shown.

[0052] Figure 4 The figure shows the specific resistance value of sludge with a sand content of 20% and the moisture content of the mud cake after filtration at different addition amounts of dewatering flocculants. Figure 4 It can be seen that when the addition amount of anionic polyacrylamide is 0.15%, the specific resistance value is reduced to 10.59×10 10 cm / g, close to 9×10 10 cm / g is in the easy dehydration area, and the moisture content of the mud cake reaches the lowest value of 52.33%. Therefore, when the addition amount of the dehydration flocculant is 0.15%, it is the optimal addition amount under the vacuum filtration state of sludge with a sand content of 20%.

[0053] Example 3

[0054] The sludge in Example 3 is prepared from the original sludge by wet screening method, and its particle size distribution is as follows: sand content 30%, powder content 55.2%, clay content 14.8%, that is, the sludge has 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 flocculants of 0%, 0.05%, 0.08%, 0.1%, 0.12%, 0.15%, 0.2% and 0.25% respectively to obtain flocculated mud with a solid content of 10%. After uniform stirring for 1 minute, the sludge was poured into a specific resistance instrument and vacuum filtered at 0.05MPa for 20 minutes or until the sludge cake broke. Calculate its specific resistance value and measure its cake moisture content. The test results are as follows: Figure 5 shown.

[0056] Figure 5 The figure shows the specific resistance value of sludge with a sand content of 30% and the moisture content of the mud cake after filtration at different addition amounts of dewatering flocculants. Figure 5 It can be seen that when the addition amount of anionic polyacrylamide is 0.12%, the specific resistance value is reduced to 11.01×10 10 cm / g, close to 9×10 10 cm / g is in the easy dehydration area, and the moisture content of the mud cake reaches the lowest value of 53.33%. Therefore, when the addition amount of the dehydration flocculant is 0.15%, it is the optimal addition amount under the vacuum filtration state of sludge with a sand content of 30%.

[0057] Example 4

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

[0059] 100g of sludge and water were mixed with anionic polyacrylamide flocculants of 0%, 0.05%, 0.08%, 0.1%, 0.12%, 0.15%, 0.2% and 0.25% respectively to obtain flocculated mud with a solid content of 10%. After uniform stirring for 1 minute, the sludge was poured into a specific resistance instrument and vacuum filtered at 0.05MPa for 20 minutes or until the sludge cake broke. Calculate its specific resistance value and measure its cake moisture content. The test results are as follows: Figure 6 shown.

[0060] Figure 6 The figure shows the specific resistance value of sludge with a sand content of 40% and the moisture content of the mud cake after filtration at different addition amounts of dewatering flocculants. Figure 6It can be seen that when the addition amount of anionic polyacrylamide is 0.10%, the specific resistance value is reduced to 12.24×10 10 cm / g, which is close to 9×10 10 cm / g is in the easy dehydration area, and the moisture content of the mud cake reaches the lowest value of 55.77%. When the addition amount of anionic polyacrylamide is 0.12%, the specific resistance is below the easy dehydration area, but the moisture content of the mud cake increases instead, and the increase is relatively large, so it is not considered as the optimal addition amount. Therefore, when the addition amount of the dehydration flocculant is 0.15%, it is the optimal addition amount under the vacuum filtration state of sludge with a sand content of 40%.

[0061] It can be seen from the above embodiments that the present invention provides a method for determining the optimal amount of dewatering flocculant added to river sludge. First, large impurities in the river sludge are removed and stirred to obtain pretreated sludge. Then, the pretreated sludge is sampled, and the sludge sand content of the sample is measured. Finally, the measured sludge sand content is substituted into the fitted relationship between the sludge sand content and the optimal dosage of the dewatering flocculant to calculate the optimal amount of dewatering flocculant required to treat the river sludge. The present invention only needs to determine the optimal amount of flocculant added during the vacuum dewatering of the sludge according to the particle size distribution of the river sludge, mainly based on the sand content. The judgment method is simple and easy, which provides convenience for the resource utilization of sludge.

[0062] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for determining the optimal amount of dewatering flocculant added to river sludge, characterized in that: The following steps are involved: (1) Pretreatment: removing large impurities from river sludge and stirring to obtain pretreated sludge; (2) sampling the pretreated sludge and determining the sand content of the sampled sludge; (3) Substituting the measured sludge sand content into the fitted relationship between the sludge sand content and the optimal dosage of the dewatering flocculant, the optimal amount of the dewatering flocculant required to treat the river sludge is calculated; The relationship between the sludge sand content x and the optimal flocculant addition amount y is: y=0.366-0.072ln(x).

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

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

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

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

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

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