A curing agent, its preparation method and application

Abstract

This invention discloses a curing agent, its preparation method, and its application, relating to the field of sludge curing. The curing agent comprises the following components: a bacterial urease solution, industrial solid waste material particles, and a solid activator. The industrial solid waste material particles include phosphogypsum, slag, and fly ash; the solid activator includes quicklime, calcium chloride, and urea. In this invention, the bacterial urease solution decomposes the urea in the solid activator to produce calcium carbonate, which then reacts chemically with quicklime and calcium chloride to form calcium carbonate precipitate. The use of industrial solid waste particles increases the porosity of the curing agent, providing more adhesion points for the generated calcium carbonate precipitate, thereby enhancing the curing effect, improving the uniformity of reinforcement, and increasing the overall strength of the sludge.

Description

Technical Field

[0001] This invention relates to the technical field of sludge solidification, and particularly to a solidifying agent, its preparation method, and its application. Background Technology

[0002] With urbanization, the accumulation of sludge from underground excavation is severe, and the existing sludge disposal method, mainly landfill, occupies a large amount of land resources. Injecting a solidifying agent into the sludge improves its overall strength, allowing the reinforced sludge to be used as a supplementary material in construction projects, "turning waste into treasure" and achieving resource utilization, which has broad engineering application prospects. Bio-enzyme-induced calcium carbonate precipitation technology utilizes a large amount of highly active urease produced by high-yield urease bacteria to hydrolyze urea into carbonate ions, which combine with calcium ions provided by a calcium source to produce calcium carbonate precipitate. Calcium carbonate crystals are relatively stable and not easily corroded or weathered, allowing them to exist stably in sludge for a long time. Sludge treated with bio-enzyme-induced calcium carbonate technology can effectively improve its strength and liquefaction resistance, achieving soil reinforcement. However, due to the small pore size of the sludge, the slurry has poor fluidity and cannot penetrate deep into the sludge, resulting in poor solidification uniformity and reinforcement effects that fail to meet engineering requirements.

[0003] Phosphogypsum, slag, and fly ash are common industrial solid waste materials. Currently, the utilization rate of these solid waste materials is low, and their stockpiling occupies a large amount of land resources and pollutes the water and soil environment. Therefore, improving the utilization rate of solid waste materials is an urgent problem to be solved. Existing technologies show that industrial solid waste materials can enhance the solidification effect of microbial-induced calcium carbonate technology. For example, the prior art disclosed in publication number CN109650685A discloses a sludge solidification agent based on microorganisms and fly ash and its method for strengthening sludge. By adding fly ash to the microbial-induced calcium carbonate precipitation technology, the shear strength of the sludge is significantly improved and the water content of the sludge is reduced. The prior art disclosed in publication number CN114687366A discloses a method for reinforcing slopes using industrial waste in conjunction with soybean urease. Phosphogypsum not only provides certain trace elements for plant growth but also optimizes the uneven precipitation of calcium carbonate. This invention uses bacterial urease as the inducing material, effectively avoiding the invasion of exogenous microorganisms into the ecological environment, making it more environmentally friendly. By combining industrial solid waste materials with bio-enzyme-induced calcium carbonate precipitation technology, the large particle size of industrial solid waste materials is used to form sufficient pore space in the sludge, providing channels for slurry infiltration and calcium carbonate precipitation, thereby simultaneously improving the uniformity and strength of sludge solidification. Summary of the Invention

[0004] The purpose of this invention is to provide a curing agent, its preparation method, and its application, aiming to solve the technical problem of improving the curing strength of the curing agent.

[0005] To achieve the above objectives, the present invention proposes a curing agent comprising the following components: a bacterial urease solution, industrial solid waste material particles, and a solid activator, wherein the industrial solid waste material particles include phosphogypsum, slag, and fly ash; and the solid activator includes quicklime, calcium chloride, and urea.

[0006] Further, by mass fraction, the curing agent comprises the following components: 1-2 parts of bacterial urease solution, 1-2 parts of industrial solid waste material particles, and 1-2 parts of solid activator.

[0007] Further, by weight, the industrial solid waste material comprises the following components: 5-10 parts phosphogypsum, 2-4 parts slag, and 3-6 parts fly ash; and / or,

[0008] The solid activator, by weight, comprises the following components: 1-2 parts quicklime, 3-6 parts calcium chloride, and 3-6 parts urea; and / or,

[0009] The activity of the bacterial urease in the bacterial urease solution was 30.76-56.98 U / mL.

[0010] Furthermore, the particle size of the slag ranges from 0.075 mm to 5 mm; and / or,

[0011] The particle size range of the fly ash is 0.075 mm to 5 mm.

[0012] Furthermore, the particle size of the quicklime ranges from 45 μm to 200 μm.

[0013] The present invention also proposes a method for preparing the above-mentioned curing agent, characterized in that the method includes the following steps:

[0014] Obtain a bacterial urease solution;

[0015] A bacterial urease solution is mixed with industrial solid waste material particles to obtain a solid waste material suspension.

[0016] A solidifying agent is obtained by mixing a suspension of solid waste materials with a solid activator.

[0017] Furthermore, in the curing agent, the mass ratio of the solid waste material suspension to the solid activator is (1~2):1.

[0018] The present invention also proposes a curing method, using the above-mentioned curing agent or a curing agent prepared by the above-mentioned curing agent preparation method, wherein the curing method for the sludge includes the following steps:

[0019] The curing agent was mixed with the sludge to obtain the test sludge;

[0020] The experimental sludge was cured.

[0021] Furthermore, the mass ratio of the curing agent to the sludge is 1:(4~9).

[0022] Furthermore, the maintenance period is 28 days; and / or,

[0023] The curing temperature is 28~32℃.

[0024] In the technical solution of this invention, a bacterial urease solution is used to decompose urea in a solid activator to produce calcium carbonate, which then reacts chemically with quicklime and calcium chloride to form calcium carbonate precipitate. By using industrial solid waste particles, the porosity of the curing agent is increased, providing more attachment points for the calcium carbonate precipitate induced by the bacterial urease solution, thereby enhancing the curing effect, improving the uniformity of reinforcement, and increasing the overall strength of the sludge. By using a solid activator, urea and a stable calcium source are provided for the calcium carbonate precipitate induced by the bacterial urease solution, ensuring that the curing agent remains stable before mixing and does not deteriorate, thus guaranteeing the curing effect of the curing agent. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0026] Figure 1 A flowchart illustrating a method for preparing a curing agent according to an embodiment of the present invention;

[0027] Figure 2 This is a flowchart of a sludge solidification method provided in an embodiment of the present invention.

[0028] The implementation, functional features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them.

[0030] It should be noted that, unless specific conditions are specified in the embodiments, conventional conditions or conditions recommended by the manufacturer should be followed. Reagents or instruments whose manufacturers are not specified are all commercially available products. Furthermore, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution that simultaneously satisfies A and B. In addition, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, such a combination should be considered non-existent and not within the scope of protection claimed by this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention.

[0031] In existing technologies, silt treated with bio-enzyme-induced calcium carbonate technology can effectively improve its strength and liquefaction resistance, thus achieving soil reinforcement. However, due to the small pore size of the silt, the slurry has poor fluidity and is difficult to penetrate into deep silt layers. Therefore, the solidification uniformity of this method is poor, and the reinforcement effect is difficult to meet engineering requirements.

[0032] In view of the problem of poor curing uniformity mentioned in the background art, the present invention proposes a curing agent comprising the following components: a bacterial urease solution, industrial solid waste material particles, and a solid activator, wherein the industrial solid waste material particles include phosphogypsum, slag, and fly ash; the solid activator includes quicklime, calcium chloride, and urea; the bacterial urease is extracted from urease-producing bacteria, such as Bacillus pasteurellii, Bacillus pasteurellii, or urease-decomposing bacteria Bacillus sp. CR2, etc., and the bacterial urease is lower in cost, has a wider range of applications, and higher activity than pure urease.

[0033] In the technical solution provided by this invention, a bacterial urease solution is used to decompose urea in the solid activator to produce calcium carbonate, which then reacts chemically with quicklime and calcium chloride to form calcium carbonate precipitate. By using industrial solid waste particles, the porosity of the curing agent is increased, providing more adhesion points for the calcium carbonate precipitate induced by the bacterial urease solution, thereby enhancing the curing effect, improving the uniformity of reinforcement, and increasing the overall strength of the sludge. In the humid environment of the sludge, the active SiO2 and Al2O3 in the fly ash react with the quicklime in the solid activator to generate hydrated calcium silicate, hydrated calcium aluminate, and other cementing substances, thus enhancing the curing effect and increasing the overall strength of the sludge. Furthermore, the slag powder in the slag can improve the activity effect of the fly ash, and under alkaline conditions, it hydrates with Ca(OH)2 to generate more CSH gel, improving the microstructure of the sludge. The structure further enhances the overall strength of the sludge. Phosphogypsum contains calcium sulfate dihydrate and a small amount of iron and aluminum compounds. Calcium sulfate dihydrate is less susceptible to environmental influences and provides a stable calcium source for the induction of calcium carbonate precipitate by bacterial urease solution. The iron and aluminum compounds react with quicklime in the moist environment of the sludge to form ettringite, filling the pores in the slag and fly ash, further improving the sludge's strength. By using a solid activator, urea and a stable calcium source are provided for the induction of calcium carbonate precipitate by bacterial urease solution, ensuring the curing agent remains stable before mixing and does not deteriorate, thus guaranteeing the curing effect. Urea provides a stable carbon source for the induction of calcium carbonate precipitate by bacterial urease solution, while quicklime and calcium chloride provide stable calcium sources. Furthermore, quicklime can chemically react with industrial solid waste to produce cementing substances, further improving the overall strength of the sludge.

[0034] In some embodiments, the curing agent comprises, by weight, the following components: 1-2 parts of bacterial urease solution, 1-2 parts of industrial solid waste material particles, and 1-2 parts of solid activator. Preferably, the curing agent comprises, by weight, the following components: 1 part of bacterial urease solution, 1 part of industrial solid waste material particles, and 1 part of solid activator.

[0035] By using similar mass proportions of bacterial urease solution, industrial solid waste material particles, and solid activator, the bacterial urease solution and solid activator can react fully, allowing the resulting calcium carbonate precipitate to completely adhere to the industrial solid waste material particles, thus improving the overall strength of the sludge. If there is too much bacterial urease solution, the amount of water that does not participate in the reaction increases after mixing, leading to a decrease in the curing effect of the solidifying agent. If there is too little bacterial urease solution, the rate of calcium carbonate precipitation slows down, resulting in a decrease in the curing effect. If there are too many industrial solid waste material particles, less calcium carbonate precipitate adheres to the particles, resulting in a decrease in the specific gravity of the solidifying agent. A decrease in surface area results in poorer sludge absorption and a reduced solidification effect. If there are too few industrial solid waste material particles, the resulting calcium carbonate precipitate will not have enough adhesion points, causing the solidifying agent to become sandy after mixing with the sludge, thus reducing the solidification effect. If there is too much solid activator, the activator will contain a large amount of unreacted quicklime and urea after mixing with the sludge, which is prone to decomposition and reduced strength of the solidified sludge, resulting in poor solidification uniformity and a reduced solidification effect. If there is too little solid activator, there will be less calcium carbonate precipitate, the specific surface area of ​​the solidifying agent will decrease, resulting in poor sludge absorption and a reduced solidification effect.

[0036] In some embodiments, the industrial solid waste material comprises, by weight, the following components: 5-10 parts phosphogypsum, 2-4 parts slag, and 3-6 parts fly ash; in some embodiments, preferably, the industrial solid waste material comprises, by weight, the following components: 5 parts phosphogypsum, 2 parts slag, and 3 parts fly ash; and / or,

[0037] By weight, the solid activator comprises the following components: 1-2 parts quicklime, 3-6 parts calcium chloride, and 3-6 parts urea. In some embodiments, preferably, by weight, the solid activator comprises the following components: 1 part quicklime, 3 parts calcium chloride, and 3 parts urea; and / or,

[0038] The activity of the bacterial urease in the bacterial urease solution was 30.76-56.98 U / mL.

[0039] Using 5-10 parts of phosphogypsum provides sufficient calcium and produces more ettringite after mixing, improving the curing effect of the curing agent. Using 2-4 parts of slag enhances the activity effect of fly ash. However, adding too much slag reduces its effect on improving the fly ash activity, decreases cementitious material, and consequently reduces the curing effect of the curing agent. Adding a small amount of quicklime activates the active SiO2 and Al2O3 in the fly ash, preventing excessive heat generation during sludge mixing that could disrupt the uniformity of curing and increase the overall compressive strength of the sludge. Adding similar amounts of calcium chloride and... Urea ensures that the mass fractions of calcium and carbon sources are similar, allowing them to react completely to form calcium carbonate precipitate, further improving the curing effect of the curing agent. By using a bacterial urease solution with an activity of 30.76-56.98 U / mL, the bacterial urease can rapidly decompose urea while reducing the amount of urease used and lowering the cost of the curing agent. If the bacterial urease activity is higher than 56.98 U / mL, the culture time of Pasteurella increases, the production cost of urease increases, and the rate of urea decomposition does not increase significantly. If the bacterial urease activity is lower than 30.76 U / mL, the rate of urea decomposition decreases, and the curing effect of the curing agent decreases.

[0040] In some embodiments, the particle size of the slag ranges from 0.075 mm to 5 mm; and / or,

[0041] The particle size range of the fly ash is 0.075 mm to 5 mm.

[0042] By limiting the particle size range of slag and fly ash to 0.075mm~5mm, the numerous pores within the slag and fly ash improve the flowability of the bacterial urease solution among the sludge particles. Consequently, the resulting calcium carbonate crystals are more evenly distributed in the sludge, enhancing the curing uniformity of the curing agent and increasing the overall compressive strength of the sludge. If the particle size is too large, the excessively large industrial solid waste particles will reduce the curing uniformity of the curing agent. If the particle size is too small, the porosity of the industrial solid waste particles will decrease, and the processing cost will be higher, without further enhancing the curing effect of the curing agent.

[0043] In some embodiments, the particle size of the quicklime ranges from 45 μm to 200 μm.

[0044] By using quicklime with a particle size range of 45μm to 200μm, the specific surface area of ​​the quicklime is increased, the contact area between the quicklime and other components during mixing is increased, and the reaction rate is increased. If the particle size of the quicklime is too large, the reaction rate during mixing will be slower, and incompletely reacted quicklime particles are easily generated, which may lead to deterioration and decomposition, resulting in a reduction in the curing effect of the curing agent. If the particle size of the quicklime is too small, the grinding cost will increase, and the reaction rate will not change significantly, and there will be no significant improvement in the curing effect of the curing agent.

[0045] The present invention also proposes a method for preparing the above-mentioned curing agent, characterized in that the method includes the following steps:

[0046] Obtain a bacterial urease solution;

[0047] A bacterial urease solution is mixed with industrial solid waste material particles to obtain a solid waste material suspension.

[0048] A solidifying agent is obtained by mixing a suspension of solid waste materials with a solid activator.

[0049] By preferentially mixing the bacterial urease solution with industrial solid waste material particles, the bacterial urease can fully penetrate into the pores of the industrial solid waste material particles. The solid waste material suspension and solid activator are stored separately and mixed evenly before mixing with sludge, thereby improving the curing uniformity of the curing agent and avoiding the formation of dense curing agent particles inside the curing agent after pre-mixing, which would not be able to absorb sludge and lead to a decrease in the curing effect of the curing agent.

[0050] In some embodiments, see Figure 1 Specifically, it includes the following steps:

[0051] The phosphogypsum was activated at 180℃ and then pulverized using a ball mill. The slag and fly ash were sieved to a particle size range of 0.075mm–5mm. Phosphogypsum, fly ash, and slag were weighed at a mass ratio of 5:2:3. A biological enzyme solution was measured at a solid-liquid ratio of 1:1. The weighed phosphogypsum, fly ash, and slag were mixed with the biological enzyme solution to prepare a solid waste suspension.

[0052] Weigh quicklime, urea, and calcium chloride in a mass ratio of 1:3:3 to prepare a solid activator. The quicklime needs to be sieved and quicklime powder with a particle size range of 45μm to 200μm should be collected.

[0053] The solid activator and the solid waste material suspension were stored in two separate temperature-controlled chambers and transported to the target area. The solid activator and the solid waste material suspension were then uniformly injected into a mixing tank and stirred to ensure that the solid activator and the solid waste material suspension were fully and evenly mixed to form a solidifying agent.

[0054] The bacterial urease solution can be obtained by purchasing or prepared by oneself. The preparation of the bacterial urease solution includes the following steps:

[0055] The pre-prepared bacterial culture medium was placed in an autoclave and sterilized at 120℃ for 30 minutes. After complete cooling, *Bacillus pasteurellii* inoculum was injected into the sterilized culture medium on a sterile workbench to prepare a microbial solution. The microbial solution was then placed in a shaker and shaken at 30℃, 150 rpm for 24 hours to obtain a mature bacterial suspension. The bacterial suspension was then placed in a circulating-cooling ultrasonic disruptor, with the ultrasonic radiation time fixed at 10 minutes and the power at 300W. The supernatant obtained after disruption and separation was the biological enzyme solution.

[0056] In some embodiments, the mass ratio of the solid waste material suspension to the solid activator in the curing agent is (1~2):1.

[0057] By using a mass ratio of solid waste material suspension to solid activator of (1~2):1, the industrial waste material particles have pores, providing attachment sites for calcium carbonate precipitation and absorbing sludge to improve the curing strength. The bacterial urease solution can fully penetrate the industrial waste material particles and provide high enzyme activity, rapidly decomposing the urea in the solid activator to generate calcium carbonate precipitate that adheres to the industrial waste material particles, thereby improving the curing effect of the curing agent. If the mass of the solid activator is greater than the mass of the solid waste material suspension, the quicklime content of the solid activator will be higher, and calcium carbonate will easily be produced in a humid environment, leading to sand formation inside the curing agent and reducing the curing effect of the curing agent.

[0058] The present invention also proposes a curing method, using the above-mentioned curing agent or a curing agent prepared by the above-mentioned curing agent preparation method, wherein the curing method for the sludge includes the following steps:

[0059] The curing agent was mixed with the sludge to obtain the test sludge;

[0060] The experimental sludge was cured.

[0061] By mixing the curing agent with the sludge, the dispersion of the curing agent in the sludge is improved, thereby increasing the overall strength of the sludge and enhancing the curing effect of the curing agent. By curing the test sludge, the degree of curing of the sludge is improved, thus enhancing the curing effect of the curing agent.

[0062] Please see Figure 2 Specifically, it includes the following steps:

[0063] The prepared curing agent was injected into the sludge using a grouting method;

[0064] The sludge containing the curing agent is stirred using a mixer to ensure that the curing agent is evenly distributed in the sludge.

[0065] A thin film was used to cover the surface of the experimental sludge for curing.

[0066] In some embodiments, the mass ratio of the curing agent to the sludge is 1:(4~9).

[0067] By adding an appropriate amount of curing agent, the curing effect of the curing agent can be guaranteed. If too much curing agent is added, the preparation cost of the test sludge will be high, and the strength of the test sludge will not be significantly improved, and the curing effect of the curing agent will be reduced. If too little curing agent is added, the excess water in the test sludge will not be able to combine with the curing agent, the overall strength of the test sludge will be reduced, and the curing effect of the curing agent will be reduced.

[0068] In some embodiments, the curing period is 26 to 30 days; and / or,

[0069] The curing temperature is 28~32℃, preferably 28 days and the curing temperature is 30℃.

[0070] By setting the curing temperature to 28-32℃ and curing for 26-30 days, the overall strength uniformity of the test sludge during the solidification process is improved. If the temperature is too high, the local strength of the test sludge will increase too quickly, leading to cracking and deformation. If the temperature is too low, the curing effect of the test sludge will be poor, and the overall strength will increase slowly. Specifically, during the curing process, the test sludge is sprayed with water every 7 days to prevent cracking and deformation.

[0071] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are only used to explain the present invention and are not intended to limit the present invention.

[0072] To facilitate verification of the feasibility of this invention, a 1m site was selected. 3 Silt, weighing 2000 kg. Please refer to [link / reference]. Figure 1 and Figure 2 The solidification method for sludge is as follows:

[0073] The pre-prepared bacterial culture medium was placed in an autoclave and sterilized at 120℃ for 30 minutes. After complete cooling, *Bacillus pasteurellii* inoculum was injected into the sterilized culture medium on a sterile workbench to prepare a microbial solution. The microbial solution was then placed in a shaker and shaken at 30℃, 150 rpm for 24 hours to obtain a mature bacterial suspension. The bacterial suspension was then placed in a circulating-cooling ultrasonic disruptor, with the ultrasonic radiation time fixed at 10 minutes and the power at 300W. The supernatant obtained after disruption and separation was the biological enzyme solution.

[0074] The phosphogypsum was activated at 180℃ and then pulverized using a ball mill. The slag and fly ash were sieved to a particle size range of 0.075mm–5mm. Phosphogypsum, fly ash, and slag were weighed at a mass ratio of 5:2:3. A biological enzyme solution was measured at a solid-liquid ratio of 1:1. The weighed phosphogypsum, fly ash, and slag were mixed with the biological enzyme solution to prepare a solid waste suspension.

[0075] Weigh quicklime, urea, and calcium chloride in a mass ratio of 1:3:3 to prepare a solid activator. The quicklime needs to be sieved and quicklime powder with a particle size range of 45μm to 200μm should be collected.

[0076] The solid activator and the solid waste material suspension were stored in two separate constant temperature chambers and transported to the target area. The solid activator and the solid waste material suspension were then uniformly injected into a mixing tank and stirred to ensure that the solid activator and the solid waste material suspension were fully and evenly mixed to form a solidifying agent.

[0077] The curing agent is poured into the sludge and then mixed with a mixer to ensure that the curing agent is evenly distributed in the sludge to be treated.

[0078] The treated sludge was cured for 28 days at a temperature of 30°C. During the curing process, the sludge was sprayed with water every 7 days. After 28 days of curing, a static cone penetration test was conducted on the solidified sludge.

[0079] Examples 1-5 and Comparative Examples 1-3 provide a test sludge, the raw materials of which include the following components and contents, as shown in Table 1:

[0080] Table 1. Composition and content of experimental sludge raw materials in Examples 1-5 and Comparative Examples 1-3

[0081] Additives Urease solution Calcium chloride Urea quicklime phosphogypsum fly ash slag silt Example 1 2.5% 3% 1.5% 0.5% 1.25% 0.5% 0.75% 90% Example 2 5% 6% 3% 1% 2.5% 1% 1.5% 80% Example 3 1.65% 1.98% 0.99% 0.33% 1.65% 0.66% 0.99% 91.75% Example 4 3.3% 3.96% 1.98% 0.66% 3.3% 1.32% 1.98% 83.5% Example 5 6% 7.25% 3.6% 1.2% 3% 1.2% 1.8% 76% Comparative Example 1 0 6% 3% 1% 2.5% 1% 1.5% 85% Comparative Example 2 5% 0 0 0 2.5% 1% 1.5% 90% Comparative Example 3 5% 6% 3% 1% 0 0 0 85% Comparison Example 2.5% 3% 1.5% 0 0 0 0 93%

[0082] In Examples 1, 2, and 5, the mass ratio of the bacterial urease solution, industrial solid waste material particles, and solid activator was 1:1:2. In Examples 3 and 4, the mass ratio of the bacterial urease solution, industrial solid waste material particles, and solid activator was 1:2:2. The raw material composition of Comparative Example 1 was the same as that of Example 2 without the bacterial urease solution. The raw material composition of Comparative Example 2 was the same as that of Example 2 without quicklime, calcium chloride, and urea. The raw material composition of Comparative Example 3 was the same as that of Example 2 without phosphogypsum, slag, and fly ash. The solid activator in Example 3 and the raw material composition of the control example were the same as those of Example 1 without quicklime, phosphogypsum, slag, and fly ash.

[0083] Table 2 shows the compressive strength of the test sludge after 28 days of curing in Examples 1-5 and Comparative Examples 1-3 of this application:

[0084] Table 2. Compressive strength of the test sludge after 28 days of curing in Examples 1-5 and Comparative Examples 1-3.

[0085]

[0086] As can be seen from the data in Table 2, the compressive strength of the sludge tested in Examples 1 to 5 after 28 days of curing was greater than 7 MPa, which was more than 5 MPa higher than that of the control sludge; while the compressive strength of Comparative Examples 1 to 3 was less than 2.5 MPa, which was less than 1 MPa higher than that of the control sludge.

[0087] Compared to Example 1, Comparative Example 1 lacked the bacterial urease solution, and its compressive strength was 1.72 MPa, which was lower than the compressive strength of 7.54 MPa in Example 1, indicating that the bacterial urease solution can improve the curing effect of the curing agent.

[0088] Comparative Example 2, lacking quicklime, calcium chloride, and urea compared to Example 1, had a compressive strength of 1.67 MPa, which was lower than the compressive strength of 7.54 MPa in Example 1. This indicates that quicklime, calcium chloride, and urea can improve the curing effect of the curing agent.

[0089] Comparative Example 3, which lacks phosphogypsum, slag, and fly ash compared to Example 1, has a compressive strength of 2.25 MPa, which is lower than the compressive strength of 7.54 MPa in Example 1. This indicates that phosphogypsum, slag, and fly ash can improve the curing effect of the curing agent.

[0090] Compared to Example 2, the curing agent ratio in Example 5 was 24%, while in Example 2 it was 20%. The compressive strength of Example 5 was 8.65 MPa, which was basically the same as the compressive strength of Example 2 (8.64 MPa). This indicates that a curing agent ratio exceeding 20% ​​has little effect on improving the curing effect of sludge.

[0091] Based on the above experiments, it can be seen that the curing agents of Examples 1 to 5 can effectively improve the compressive strength of sludge and have a high curing effect.

[0092] Comparing Comparative Example 1 with Example 1 shows that the bacterial urease solution can improve the curing effect of the curing agent;

[0093] Comparing Comparative Example 2 with Example 1, it can be shown that quicklime, calcium chloride, and urea can improve the curing effect of the curing agent;

[0094] Comparing Comparative Example 3 with Example 1, it can be shown that phosphogypsum, slag, and fly ash can improve the curing effect of the curing agent.

[0095] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the patent protection scope of the present invention.

Claims

1. A curing agent, characterized in that, Includes the following components: Bacterial urease solution; Industrial solid waste material particles, including phosphogypsum, slag, and fly ash; and, Solid activators include quicklime, calcium chloride, and urea; among which: By weight, the curing agent comprises 1-2 parts of bacterial urease solution, 1-2 parts of industrial solid waste material granules, and 1-2 parts of solid activator; the industrial solid waste material comprises 5-10 parts of phosphogypsum, 2-4 parts of slag, and 3-6 parts of fly ash; the solid activator comprises 1-2 parts of quicklime, 3-6 parts of calcium chloride, and 3-6 parts of urea. The activity of the bacterial urease in the bacterial urease solution was 30.76-56.98 U / mL; The particle size range of the slag is 0.075 mm to 5 mm; The particle size range of the fly ash is 0.075 mm to 5 mm; The particle size range of the quicklime is 45μm to 200μm.

2. A method for preparing the curing agent according to claim 1, characterized in that, The method includes the following steps: Obtain a bacterial urease solution; A bacterial urease solution is mixed with industrial solid waste material particles to obtain a solid waste material suspension. A solidifying agent is obtained by mixing a suspension of solid waste materials with a solid activator.

3. The method for preparing the curing agent as described in claim 2, characterized in that, In the curing agent, the mass ratio of the solid waste material suspension to the solid activator is (1~2):

1.

4. A method for solidifying sludge, characterized in that, The method for solidifying the sludge using a solidifying agent prepared by a method according to claim 1 or any one of claims 2 to 3 includes the following steps: The curing agent was mixed with the sludge to obtain the test sludge; The experimental sludge was cured.

5. The curing method as described in claim 4, characterized in that, The mass ratio of the curing agent to the sludge is 1:(4~9).

6. The curing method as described in claim 4, characterized in that, The maintenance period is 26-30 days; and / or, The curing temperature is 28~32℃.

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