A sand reinforcement test device based on microbial mineralization technology

Abstract

The embodiment of the present application provides a sand reinforcement test device based on a microbial mineralization technology, comprising a cementing liquid providing module, which is used for providing cementing liquid and mixing preset gas suitable for survival of microorganisms; a microbial mineralization reaction module, which is connected with the cementing liquid providing module and is used for storing sand, microorganisms and cementing liquid, and mixing them to obtain a mixture, so that the microorganisms produce a mineralization reaction on the sand; a monitoring module, which is connected with the microbial mineralization reaction module and is used for monitoring pH value and dissolved oxygen content of the mixture; and a temperature control module, which is connected with the microbial mineralization reaction module and is used for controlling temperature inside the microbial mineralization reaction module. The device mixes the microorganisms and the cementing liquid attached to the sand grains uniformly through stirring, and adjusts the dissolved oxygen concentration of the cementing liquid, so as to provide a more suitable habitat for different types of microorganisms. The pH and dissolved oxygen data obtained by the monitoring module will provide a theoretical basis for application of the microbial mineralization technology in actual engineering.

Description

Technical Field

[0001] This invention relates to the technical field of soil reinforcement, and in particular to a test device for sand reinforcement based on microbial mineralization technology. Background Technology

[0002] Soil stabilization based on microbial mineralization technology is an innovative bioengineering technique that utilizes the metabolic activity of microorganisms to transform soluble minerals in the soil into insoluble mineral deposits, such as calcium carbonate and silicates, thereby improving the soil's strength and durability. Compared to traditional physical or chemical stabilization methods, this technology offers advantages such as environmental friendliness, cost-effectiveness, and sustainability. Currently commonly used methods include injection, spraying, and soaking.

[0003] In large-area or deep soil treatment, injection methods often fail to ensure uniform distribution of microbial inoculants and cementing solutions across the entire soil profile. This can result in some areas showing better mineralization while others perform poorly, impacting the overall reinforcement effect.

[0004] Spraying primarily targets the soil surface, making it difficult to ensure that the bacterial solution and cementing solution penetrate deep into the soil. Its effectiveness is limited when treating deeply reinforced soils. During spraying, environmental conditions such as wind speed, humidity, and temperature can affect the spraying effect. For example, strong winds may cause uneven dispersion of the bacterial solution and cementing solution, while excessively high or low temperatures may affect the activity of microorganisms and the mineralization effect.

[0005] Immersion methods typically require a lengthy soaking process to ensure sufficient penetration and reaction of microorganisms and the cementing solution. Furthermore, the mineralization process involves the use of large quantities of cementing solution to completely submerge the sandy soil sample. For large-scale soil remediation projects, this results in high material costs and resource consumption. Summary of the Invention

[0006] In view of the above problems, embodiments of the present invention are proposed to provide a sand reinforcement test device based on microbial mineralization technology to overcome or at least partially solve the above problems.

[0007] To address the aforementioned problems, this invention discloses a sand reinforcement test device based on microbial mineralization technology, comprising:

[0008] A cementing fluid supply module is used to supply cementing fluid and mix a preset gas suitable for microbial survival into the cementing fluid;

[0009] a microorganism mineralization reaction module, connected with the cementation fluid providing module, for storing sand, microorganisms, and the cementation fluid obtained from the cementation fluid providing module, and mixing the sand, the microorganisms, and the cementation fluid to obtain a mixture, so that the microorganisms produce a mineralization reaction on the sand;

[0010] a monitoring module, connected with the microorganism mineralization reaction module, for monitoring preset parameters of the mixture; the preset parameters include pH value and dissolved oxygen content;

[0011] a temperature control module, connected with the microorganism mineralization reaction module, for controlling the temperature inside the microorganism mineralization reaction module.

[0012] Optionally, the cementation fluid providing module comprises:

[0013] a liquid inlet tank for storing cementation fluid;

[0014] a gas tank connected with the liquid inlet tank through a conduit, for providing a preset gas suitable for the survival of microorganisms; a gas collection bag connected with the liquid inlet tank through a conduit, for collecting residual gas in the liquid inlet tank that is not mixed into the cementation fluid;

[0015] a first gas washing bottle connected on the conduit between the gas collection bag and the liquid inlet tank, for absorbing water-soluble gas from the liquid inlet tank through water stored in the first gas washing bottle;

[0016] a first pump having one end connected to the liquid inlet tank through a pump pipe and the other end connected to the microorganism mineralization reaction module through a pump pipe, for pumping the cementation fluid mixed with the preset gas in the liquid inlet tank into the microorganism mineralization reaction module.

[0017] Optionally, the microorganism mineralization reaction module comprises:

[0018] an intermittent reactor, the intermittent reactor comprising a top cover and a bottom cover, the top cover having a gas outlet; for storing sand, microorganisms, and the cementation fluid obtained from the cementation fluid providing module;

[0019] a second gas washing bottle connected from the gas outlet of the top cover to the intermittent reactor through a conduit, for absorbing water-soluble gas from the intermittent reactor through water stored in the gas washing bottle;

[0020] a stirrer for mixing the sand, the microorganisms, and the cementation fluid stored in the intermittent reactor to obtain a mixture;

[0021] a liquid outlet tank for collecting residual cementation fluid in the intermittent reactor;

[0022] A second pump, one end of which is connected to the intermittent reactor through a pump pipe, and the other end of which is connected to the liquid outlet tank through a pump pipe, is used to pump the remaining cementation liquid in the intermittent reactor into the liquid outlet tank.

[0023] Optionally, the monitoring module comprises:

[0024] A pH probe is used to collect the pH value of the mixture.

[0025] A dissolved oxygen probe is used to collect the dissolved oxygen content of the mixture.

[0026] A monitor, one end of which is connected to the pH probe, and the other end of which is connected to the dissolved oxygen probe, is used to monitor the pH value and dissolved oxygen content of the mixture.

[0027] Optionally, the temperature control module comprises:

[0028] A water bath sandwich is wrapped outside the intermittent reactor, and stores constant temperature water inside to keep the intermittent reactor at a constant temperature.

[0029] A constant temperature water bath is connected to the water bath sandwich through a conduit, and is used to provide constant temperature water to the water bath sandwich.

[0030] Optionally, the cementation liquid providing module further comprises:

[0031] An aeration head is arranged at the end of the conduit connected from the gas tank to the liquid inlet tank, and is used to expose the preset gas from the gas tank into the liquid inlet tank.

[0032] A three-way valve, the gas collection bag and the gas washing bottle are connected to both ends of the three-way valve through silica gel pipes, and the other end of the three-way valve is connected to the top of the liquid inlet tank, and is used to control the flow of gas in the three directions.

[0033] Optionally, the preset gas comprises nitrogen or oxygen, nitrogen is used to maintain an environment suitable for the survival of microorganisms, and oxygen is used to supplement when the dissolved oxygen content in the cementation liquid is insufficient.

[0034] Optionally, the components of the cementation liquid in the liquid inlet tank include calcium chloride and urea; or calcium nitrate and sodium acetate.

[0035] Optionally, the stirrer comprises an adjustable speed motor, a stirring paddle and a coupling.

[0036] Optionally, one end of the first pump is connected to the liquid inlet tank through a pump pipe, and the other end of the first pump is connected to the bottom cover of the intermittent reactor through a pump pipe, and is used to pump the cementation liquid into the intermittent reactor.

[0037] The second pump is inserted into the intermittent reactor through the pump pipe at a corresponding height, and the other end is connected to the liquid outlet tank through the pump pipe, for pumping the remaining cementing fluid in the intermittent reactor into the liquid outlet tank.

[0038] Optionally, the cementing fluid provided by the cementing fluid providing module has a dissolved oxygen concentration adapted to the microorganism.

[0039] Optionally, the pH probe and the dissolved oxygen probe are made of acid and alkali resistant and corrosion resistant materials.

[0040] Optionally, the cementing fluid providing module further comprises a pressure reducing valve arranged in a conduit connecting the liquid inlet tank and the gas tank, for controlling the flow of the preset gas transmitted from the gas tank to the liquid inlet tank through the conduit.

[0041] Optionally, the cementing fluid providing module further comprises a check valve arranged on the pump pipe between the first pump and the microorganism mineralization reaction module, for controlling the cementing fluid pumped into the microorganism mineralization reaction module.

[0042] Optionally, an output valve is arranged on the pump pipe between the intermittent reactor and the second pump, for controlling the cementing fluid pumped out of the intermittent reactor.

[0043] The embodiments of the present application have the following advantages:

[0044] The present application provides a sand reinforcement test device based on microorganism mineralization technology, comprising: a cementing fluid providing module, for providing cementing fluid and mixing in a preset gas suitable for the survival of microorganisms; a microorganism mineralization reaction module connected with the cementing fluid providing module, for storing sand, microorganisms and cementing fluid obtained from the cementing fluid providing module, and stirring and mixing to obtain a mixture, so that the microorganisms produce mineralization reaction on the sand; a monitoring module connected with the microorganism mineralization reaction module, for monitoring the pH value and dissolved oxygen content of the mixture; and a temperature control module connected with the microorganism mineralization reaction module, for controlling the temperature inside the microorganism mineralization reaction module. The device mixes the microorganisms and the cementing fluid attached to the sand uniformly by stirring, and adjusts the dissolved oxygen concentration of the cementing fluid, to provide a more suitable habitat for different types of microorganisms. The pH and dissolved oxygen data obtained by the online monitoring instrument will provide a theoretical basis for the application of microorganism mineralization technology in practical engineering. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 is a structural block diagram of a sand reinforcement test device based on microorganism mineralization technology provided by the embodiments of the present application;

[0046] Figure 2Fig. 2 is a structural schematic diagram of another sand reinforcement test device based on the microbial mineralization technology according to an embodiment of the present application.

[0047] Legend of reference signs:

[0048] 10-cementing liquid providing module, 11-microbial mineralization reaction module, 12-monitoring module, 13-temperature control module, 101-liquid inlet tank, 102-gas tank, 103-pressure reducing valve, 104-gas collection bag, 105-first gas washing bottle, 106-first pump, 107-check valve, 108-aeration head, 109-three-way valve, 111-intermittent reactor, 1111-top cover, 1112-bottom cover, 112-second gas washing bottle, 113-stirrer, 1131-motor, 1132-coupling shaft, 1133-stirring paddle, 114-liquid outlet tank, 115-second pump, 116-output valve, 121-pH probe, 122-dissolved oxygen probe, 123-monitor, 131-water bath interlayer, 132-constant temperature water bath. DETAILED DESCRIPTION

[0049] In order to make the above-mentioned objects, features and advantages of the present application more apparent and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0050] In sand reinforcement, MICP (Microbially Induced Calcite Precipitation, MICP for short, a technology for promoting calcium carbonate precipitation by using microbial metabolic activity) technology has been successfully applied in dam seepage prevention treatment, road foundation reinforcement, desertification prevention and other fields. Compared with traditional materials such as cement, the microbial bacteria liquid used in MICP technology has low viscosity and requires small grouting pressure, which is more suitable for long-distance and large-area reinforcement operations and reduces the burden on the environment. The microbial reinforcement process is a naturally occurring biochemical reaction, which reduces energy consumption and pollutant emissions, and meets the requirements of green building and sustainable development.

[0051] Under suitable conditions, specific microorganisms (such as urea-decomposing bacteria such as Bacillus pasteurii) can decompose urea into ammonia and carbon dioxide, and these microorganisms can also catalyze the reaction of carbon dioxide and water to generate carbonic acid, which further reacts with calcium ions in the environment to generate insoluble calcium carbonate precipitate. As a natural "cementing agent", calcium carbonate precipitate forms a bridge between sand particles, significantly improving the overall strength and stability of the soil and reducing permeability. Microbial species, nutrient solution concentration, calcium source supply, pH value, temperature and initial conditions of sand are all key factors affecting the effect of MICP. Adjusting the concentration of the cementing liquid can control the size and distribution of calcium carbonate crystals, thereby affecting the solidification effect.

[0052] With the deepening understanding of the mechanism of microbial mineralization and the continuous progress of engineering technology, MICP technology will be more widely and efficiently applied in the reinforcement of sand and other types of soil. Sand reinforcement based on microbial mineralization technology is a potential field, which not only provides a new idea for solving the reinforcement problem in civil engineering, but also contributes to environmental protection and sustainable development.

[0053] One of the core ideas of the embodiments of the present application is that by mechanical stirring, the bacterial solution and the cementing solution are fully mixed with the soil sample, which can ensure the uniform distribution of microorganisms and cementing solution in the soil, improve the uniformity and effect of mineralization reaction. The dissolved oxygen content of deep soil is low, and the activity of aerobic bacteria is inhibited, which may lead to uneven overall consolidation. By adjusting the dissolved oxygen concentration of the cementing solution, a more suitable habitat is provided for different types of microorganisms. Explore the aerobic-anaerobic multi-microbial mineralization system to achieve deeper soil reinforcement. A large amount of soil samples can be treated in a relatively short time, which is particularly suitable for small and medium-sized soil improvement projects, and improves work efficiency.

[0054] Reference Figure 1 , shows the structure block diagram of a sand reinforcement test device based on microbial mineralization technology provided by the embodiments of the present application, which can specifically include the following modules:

[0055] The cementing solution providing module 10 is used to provide cementing solution and mix a preset gas suitable for the survival of microorganisms in the cementing solution.

[0056] In the microbial mineralization technology, the cementing solution (also known as mineralization solution or induction solution) plays a crucial role. It is a carefully prepared solution that contains the nutrients and chemical components required for microbial growth, which is used to trigger the mineralization reaction of microorganisms, thereby forming mineral deposits in soil, rock or other materials, and enhancing their physical and mechanical properties. The cementing solution contains nutrients necessary for microbial growth, such as carbon source, nitrogen source, phosphorus source, trace elements, etc., which serve as energy sources for microorganisms to support their metabolic activities. The components in the cementing solution can adjust the environmental conditions of the soil or solution, such as pH value, oxidation-reduction potential, etc., to create a microenvironment suitable for the growth of specific microorganisms, and promote the occurrence of mineralization reaction. The chemical components in the cementing solution can directly participate in or catalyze the microbial-induced mineralization reaction, such as the precipitation of calcium carbonate, by increasing the concentration of calcium ions and carbonate ions, to promote the formation of minerals. In some applications, the cementing solution serves as a carrier to inoculate microorganisms into the target area, ensuring that microorganisms can be evenly distributed and start their mineralization effect. By adjusting the formula of the cementing solution, such as changing the proportion of nutrients, pH value, buffer capacity, etc., the rate of microbial mineralization reaction and the type of minerals formed can be controlled to achieve the best reinforcement effect.

[0057] A microbial mineralization reaction module 11 is connected with the cementation fluid providing module, used for storing the sand, the microorganisms and the cementation fluid obtained from the cementation fluid providing module, and mixing the sand, the microorganisms and the cementation fluid to obtain a mixture, so that the microorganisms produce a mineralization reaction on the sand.

[0058] The by-products produced by the microbial metabolic process, such as ammonia, change the chemical environment of the soil, promote the reaction of calcium ions and carbonate ions in the soil solution, and form insoluble calcium carbonate precipitates. These precipitates act as "cement" to fill between soil particles, enhancing the cohesion and strength of the soil. Over time, the mineral deposits caused by microbial mineralization reactions gradually accumulate, improving the soil structure and enhancing its physical and mechanical properties, such as increased compressive strength and reduced permeability, thereby improving the stability and bearing capacity of the soil.

[0059] Traditional injection methods use peristaltic pumps to deliver bacterial solution and cementation fluid. The use of peristaltic pumps can accurately control the flow of liquid, ensuring the repeatability and accuracy of the experiment. After mixing the cementation fluid with the bacterial solution, the metabolic activity of the microorganisms causes a mineralization reaction, and the loose sand particles gradually cement into a whole with certain strength. However, in large-area or deep-soil treatment, it is difficult to ensure the uniform distribution of microbial solution and cementation fluid in the entire soil profile through injection method, which may result in better mineralization effect in some areas and poor effect in other areas, affecting the overall reinforcement effect.

[0060] In the microbial mineralization reaction module of the present application, the urease-producing bacteria and other mixed strains cultured and purified in advance in the laboratory, the sand to be mineralized, and the cementation fluid provided by the cementation fluid providing module, which has been configured with appropriate pH value and dissolved oxygen content, are mixed uniformly, so that the mineralization reaction of the microorganisms is more complete.

[0061] A monitoring module 12 is connected with the microbial mineralization reaction module, used for monitoring preset parameters of the mixture; the preset parameters include pH value and dissolved oxygen content.

[0062] The microbial mineralization process is affected by various environmental factors, including temperature, pH value, oxygen supply, etc. Small-scale field tests or laboratory simulations are usually required to evaluate the reinforcement effect of microbial mineralization on specific soil bodies. The reinforcement effect is verified and process parameters are adjusted by connecting pH probes and dissolved oxygen probes through a monitoring instrument for continuous monitoring. By accurately controlling these conditions, the mineralization rate and mineral formation can be optimized, and the reinforcement effect can be improved.

[0063] A temperature control module 13 is connected with the microbial mineralization reaction module, used for controlling the temperature inside the microbial mineralization reaction module.

[0064] The main functions of the temperature control module include: temperature regulation, the temperature control module can accurately control the temperature in the reactor to keep it within a certain range; heating and cooling, in the case of needing heating, the temperature control module can increase the temperature in the reactor through heating elements, while in the case of needing cooling, it can reduce the temperature through the cooling system; temperature monitoring, the temperature control module is usually equipped with temperature sensors that can monitor the temperature change in the reactor in real time and feed back the data to the control system; automatic control, modern temperature control modules usually have automatic adjustment function, which can automatically adjust the heating or cooling power according to the preset temperature setting value to maintain constant temperature; safety protection, the temperature control module also includes over-temperature protection mechanism to prevent safety hazards caused by high temperature.

[0065] In the microbial mineralization device, the design and selection of the temperature control module depend on multiple factors, including: temperature range, according to the types of microorganisms used and the reaction conditions, determine the temperature range that the temperature control module needs to cover; accuracy requirement, different microorganisms have different sensitivity to temperature, so the appropriate accuracy of the temperature control module needs to be selected according to the experimental requirements; reactor size, the power and design of the temperature control module need to match the size and volume of the reactor to ensure the uniformity and effectiveness of temperature control; energy consumption and cost, when selecting the temperature control module, its energy consumption and operating cost also need to be considered to ensure economic benefits.

[0066] The present application provides a kind of sand reinforcement test device based on microbial mineralization technology, and the device is provided by cementing fluid module, microbial mineralization reaction module, monitoring module and temperature control module.Cementing fluid module can determine aerobic or anaerobic condition according to the needs of microorganism;Microbial mineralization reaction module has stirring device, which can make microorganism and cementing fluid fully mix;Monitoring module is composed of pH probe and dissolved oxygen probe, and data parameters are monitored in time;Temperature control module can maintain the temperature required for reaction for a long time.Using this device can maintain high activity of microorganisms, and can avoid problems such as low mineralization efficiency caused by pore blockage.The device is simple in arrangement, flexible in operation, and the bacteria solution and cementing fluid used are harmless to the environment, which optimizes the microbial mineralization technology, and the data parameters obtained can provide theoretical basis for the application of soil reinforcement in practical engineering.

[0067] Referring to Figure 2 , another structure schematic diagram of the sand reinforcement test device based on microbial mineralization technology is shown, wherein,

[0068] The cementing fluid module 10 comprises:

[0069] Liquid inlet tank 101 for storing cementing fluid;

[0070] The liquid inlet tank 101 is a closed container with three ports, namely, an air inlet port, an air outlet port and a liquid outlet port. The cementing liquid contained therein is a mixture of calcium chloride and urea if the normal mineralization reaction is to be performed, or a mixture of calcium nitrate and sodium acetate if the nitration reaction is to be performed. The specific composition of the cementing liquid can be carefully configured according to the nutrients and chemicals required for the growth of microorganisms.

[0071] The gas tank 102 is connected to the liquid inlet tank 101 through a conduit and is used to provide a preset gas suitable for the survival of microorganisms.

[0072] The gas tank 102 is used as a nitrogen tank in most cases. Whether the microorganisms are anaerobic or aerobic, in special cases where the oxygen content of normal air is still insufficient, oxygen can be filled in the gas tank to supplement the dissolved oxygen content of the cementing liquid. The dissolved oxygen concentration of the cementing liquid provided by the cementing liquid providing module is adapted to the microorganisms.

[0073] The pressure reducing valve 103 is arranged in the conduit connecting the liquid inlet tank 101 and the gas tank 102 and is used to control the flow of the preset gas transmitted from the gas tank 102 to the liquid inlet tank 101 through the conduit.

[0074] The gas collection bag 104 is connected to the liquid inlet tank 101 through a conduit and is used to collect the remaining gas in the liquid inlet tank 101 that is not mixed with the cementing liquid.

[0075] After the reaction starts, the lost nitrogen or oxygen in the water inlet tank can also be replenished to maintain the anaerobic or aerobic environment for a long time.

[0076] The first gas washing bottle 105 is connected to the conduit between the gas collection bag 104 and the liquid inlet tank 101 and is used to absorb the water-soluble gas from the liquid inlet tank 101 through the water stored in the first gas washing bottle 105.

[0077] The gas washing bottle has a very wide range of specific applications. Different absorbents can be selected according to the types of impurities to be removed, for example, an alkaline solution such as sodium hydroxide solution can be used to absorb acidic gases such as hydrogen chloride; copper sulfate solution can be used to absorb ammonia gas; concentrated sulfuric acid can be used to dry the gas to remove the water content therein, etc. In the present embodiment, the first gas washing bottle 105 mainly contains water and is used to absorb the excess water-soluble gas to balance the pressure in the liquid inlet tank 101.

[0078] The first pump 106 has one end connected to the liquid inlet tank 101 through a pump pipe and the other end connected to the microbial mineralization reaction module through a pump pipe and is used to pump the cementing liquid mixed with the preset gas in the liquid inlet tank 101 into the microbial mineralization reaction module.

[0079] The first pump 106 is a peristaltic pump, also known as a hose pump or roller pump, which is a positive displacement pump particularly suitable for precise, continuous, and adjustable flow of liquid transmission. Its core working principle is to push the liquid to flow by extruding a section of elastic hose, rather than relying on traditional piston or vane mechanism. The advantages of peristaltic pump include: high precision in flow control, suitable for precise transmission of micro to large flow; because the liquid only contacts the hose, it is very suitable for transporting sensitive liquids such as pharmaceutical liquids, food raw liquids, etc., easy to clean and disinfect; can be self-suction to start, can extract liquid from the container without additional suction equipment; can handle almost any nature of liquid, including particles, high viscosity, strong corrosive or volatile liquids; only need to replace the hose periodically, low maintenance cost. In this embodiment, the cementation liquid pumped into the batch reactor can be precisely controlled, and the mineralization reaction can be precisely controlled.

[0080] The check valve 107 is arranged on the pump pipe between the first pump 106 and the microbial mineralization reaction module, and is used to control the cementation liquid pumped into the microbial mineralization reaction module.

[0081] The aeration head 108 is arranged at the end of the conduit connected from the gas tank 102 to the liquid inlet tank 101, and is used to expose the preset gas from the gas tank 102 to the liquid inlet tank 101.

[0082] The aeration head is a key component in the process of sewage treatment and water treatment, mainly used for filling air into the sewage treatment tank or biochemical reaction tank to provide oxygen required for microbial growth and promote the oxidation and decomposition of organic matter in the biological treatment process. Aeration not only increases the dissolved oxygen in water, but also can stir the water body, enhance the contact between pollutants and microorganisms, and improve the treatment efficiency.

[0083] The three-way valve 109 is connected at two ends of the three-way valve 109 through silica gel pipes of the gas collecting bag 104 and the first gas washing bottle 105, and the other end of the three-way valve 109 is connected at the top of the liquid inlet tank 101, which is used to control the gas flow in the conduit of three directions.

[0084] The microbial mineralization reaction module 11 comprises:

[0085] The batch reactor 111 comprises a top cover 1111 and a bottom cover 1112, and the top cover 1111 has a gas outlet; the batch reactor 111 is used to store sand, microorganisms, and cementation liquid obtained from the cementation liquid providing module.

[0086] This is the core part of the device, which is used to cultivate specific microbial strains, such as urea-decomposing bacteria and sulfur-oxidizing bacteria, which can promote the precipitation of minerals in the soil. The microorganisms in this embodiment are mainly mixed strains of urease-producing bacteria and other strains after laboratory cultivation and purification.

[0087] A second gas washing bottle 112 is connected to the intermittent reactor 111 through a conduit from the gas outlet of the top cover 1111, for absorbing water-soluble gases from the intermittent reactor 111 by water stored in the second gas washing bottle 112.

[0088] A stirrer 113 is used to mix the sand, microorganisms and cementing liquid stored in the intermittent reactor 111 to obtain a mixture;

[0089] The stirrer 113 further includes an adjustable speed motor 1131, a stainless steel shaft 1132 and a stirring paddle 1133.

[0090] The stirrer can make the microorganisms, nutrients and chemical reagents uniformly distributed in the solution by stirring the reaction medium, ensuring that all components can effectively participate in the mineralization process. Through stirring, the contact area between the reaction medium and the solid particles can be increased, promoting the full contact of microorganisms with the surface of soil particles, thereby improving the mineralization efficiency. The stirrer can help control the temperature, pH value and other conditions of the reaction medium, ensuring that the microorganisms are in the best working environment. Stirring can accelerate the mass transfer process in the reaction medium, making the substances produced by microbial metabolism diffuse faster to all parts of the reaction medium, which is beneficial to the progress of the mineralization reaction. Stirring helps to avoid the stratification of precipitates in the reaction medium, ensuring that the solution remains uniform and consistent, which is very important for maintaining the continuity and consistency of the reaction. Through effective stirring, the speed of the microbial mineralization reaction can be accelerated, the treatment time can be shortened, and the overall efficiency can be improved.

[0091] A liquid outlet tank 114 is used to collect the remaining cementing liquid in the intermittent reactor 111.

[0092] It is mainly used for collecting and storing the solution after the microbial mineralization reaction. This solution usually contains microbial metabolites, unreacted raw materials and possible mineral precipitates, etc. The solution discharged from the reactor is collected to facilitate subsequent treatment or analysis. The liquid outlet tank is usually equipped with monitoring instruments and sampling ports to facilitate regular inspection of the chemical composition, pH value, turbidity and other parameters of the solution, and to collect samples for detailed analysis. In some cases, the solution in the liquid outlet tank will be reintroduced into the microbial mineralization reactor to improve the mineralization efficiency or ensure that the microorganisms have sufficient nutrients.

[0093] A second pump 115 is connected to the intermittent reactor 111 through a pump pipe at one end and to the liquid outlet tank 114 through a pump pipe at the other end, for pumping the remaining cementing liquid in the intermittent reactor 111 into the liquid outlet tank 114.

[0094] An output valve 116 is provided on the pump pipe between the intermittent reactor 111 and the second pump 115, for controlling the cementing liquid pumped out of the intermittent reactor 111.

[0095] The outlet tank 114 is equipped with a second pump 115, an output valve 116 to regulate the inflow and outflow rate of the solution, ensure the stable operation of the whole system, and also prevent the solution from leaking in case of overfilling or unexpected situations. In soil reinforcement or contaminated soil remediation projects, the outlet tank can help collect and treat the solution containing mineral precipitates to evaluate the mineralization effect and recycle the precipitates.

[0096] The monitoring module 12 is connected to the microbial mineralization reaction module and is used to monitor the preset parameters of the mixture; the preset parameters include pH value and dissolved oxygen content;

[0097] The pH probe 121 is used to collect the pH value of the mixture;

[0098] The dissolved oxygen probe 122 is used to collect the dissolved oxygen content of the mixture;

[0099] Monitoring the dissolved oxygen level in the reaction medium is crucial for the mineralization reaction of aerobic microorganisms. Changes in dissolved oxygen levels can reflect the strength of microbial activity and whether additional aeration or changes in other conditions are needed to maintain an appropriate dissolved oxygen level.

[0100] The monitor 123 is connected to the pH probe 121 at one end and the dissolved oxygen probe 122 at the other end, and is used to monitor the pH value and dissolved oxygen content of the mixture.

[0101] The monitoring probe is connected to the monitor, which can display the readings in real time and record the data for subsequent analysis. The pH probe and dissolved oxygen probe are made of acid and alkali resistant and corrosion resistant materials. Through these monitoring probes, the operator can adjust the reaction conditions in a timely manner to optimize the effect of the microbial mineralization process.

[0102] The temperature control module 13 is connected to the microbial mineralization reaction module and is used to control the temperature inside the microbial mineralization reaction module.

[0103] The water bath sandwich 131 is wrapped outside the batch reactor 111;

[0104] The constant temperature water bath 132 is connected to the water bath sandwich 131 through a conduit and is used to provide constant temperature water to the water bath sandwich 131 to maintain the constant temperature of the batch reactor 111.

[0105] Temperature is very important for the microbial mineralization process, as it directly affects the growth rate of microorganisms, metabolic activity, and the efficiency of the mineralization reaction. This embodiment controls the constant temperature of the batch reactor 111 by water bath method, which can accurately control the temperature and has low energy consumption and operating cost.

[0106] In order to enable those skilled in the art to better understand the embodiments of the present application, the embodiments of the present application are described below through a reaction process example:

[0107] The gas tank 102 is connected to the aeration head 108 through the pneumatic PU pipe and is placed into the liquid inlet tank 101. The pressure reducing valve 103 controls the flow of nitrogen gas from the gas tank 102 into the liquid inlet tank 101, so as to mix the calcium chloride and urea mixed solution cementation liquid in the liquid inlet tank 101 with nitrogen gas. The excess nitrogen gas is controlled to enter the gas collection bag 104 through the three-way valve 109. The liquid inlet tank 101 is a sealed container. The excess water-soluble gas (such as carbon dioxide, etc.) is discharged to the first gas washing bottle 105 through the conduit, so as to maintain the pressure in the liquid inlet tank 101.

[0108] The first pump 106 pumps the mixed cementation liquid with suitable pH value and dissolved oxygen content in the liquid inlet tank 101 into the batch reactor 111 through the pump pipe and the check valve 107. The culture and purified microorganisms and the sand to be mineralized are placed in the batch reactor 111 in advance. After the cementation liquid is pumped in, the stirrer 113 is started to stir. The stirrer 113 controls the stirring paddle 1133 to stir the mud mixture of the cementation liquid, the sand and the microorganisms through the stainless steel coupling 1132 controlled by the adjustable speed motor 1131.

[0109] At the same time, the constant temperature water bath 132 containing constant temperature water is opened. The water is injected into the water bath interlayer 131 wrapped outside the batch reactor 111 through the PVC hose, so as to maintain the constant temperature environment suitable for the microorganism reaction in the batch reactor 111. The batch reactor 111 includes a water outlet top cover 1111 and a detachable bottom cover 1112, both of which are made of organic glass material. The top cover 1111 has a gas outlet, and the second gas washing bottle 112 is connected to the gas outlet. The second gas washing bottle 112 is filled with water like the first gas washing bottle 105, and is used to absorb the gas such as carbon dioxide generated in the batch reactor 111, so as to maintain the pressure in the batch reactor 111.

[0110] The pH probe 121 is placed at the middle left position of the batch reactor 111, and the dissolved oxygen probe 122 is placed at the middle right position of the batch reactor 111. Both the pH probe 121 and the dissolved oxygen probe 122 are connected to the external online monitor 123 through wires, and jointly monitor the pH value and the dissolved oxygen content of the mud and water mixture in the batch reactor 111.

[0111] After the reaction is completed, the stirring is stopped, and the sand is allowed to settle down. The pump pipe is inserted into the batch reactor 111 to a corresponding height through the second pump 115 and the cementation liquid output valve 116. After the sand is settled, the remaining cementation liquid is pumped out and discharged to the liquid outlet tank 114. The solidified sand in the batch reactor 111 can be taken out through the detachable bottom cover 1112.

[0112] In the description of the application, it should be understood that the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the application. In the description of the application, the meaning of "a plurality of" is two or more, unless otherwise specified.

[0113] In addition, the terms "mounting", "connecting", "connecting" should be broadly understood, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be connected inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0114] Although the preferred embodiments of the embodiments of the application have been described, those skilled in the art can make further changes and modifications to these embodiments once they know the basic inventive concept. Therefore, the appended claims are intended to include the preferred embodiments and all changes and modifications falling within the scope of the embodiments of the application.

[0115] Finally, it should be noted that in this paper, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more features. Relationship terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations. Moreover, the terms "include", "contain" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or terminal device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or includes elements inherent to such process, method, article or terminal device. Without more limitations, the element defined by the sentence "including a" does not exclude the presence of other identical elements in the process, method, article or terminal device including the element.

[0116] The above describes in detail the sand reinforcement test device based on the microbial mineralization technology provided by the present application, and the principles and implementation manners of the present application are described by using specific examples. The above description of the examples is only used to help understand the method of the present application and its core idea. Meanwhile, for those skilled in the art, the specific implementation manners and application ranges will be changed according to the idea of the present application. In summary, the content of the present description should not be understood as a limitation of the present application.

Claims

1. A sand reinforcement test device based on a microbial mineralization technique, characterized by, The application relates to a microorganism mineralization reaction device. The device comprises: a cementing fluid providing module for providing cementing fluid and mixing preset gas suitable for microorganism survival in the cementing fluid; a microorganism mineralization reaction module connected with the cementing fluid providing module, for storing sand, microorganisms and the cementing fluid obtained from the cementing fluid providing module, and mixing the sand, the microorganisms and the cementing fluid to obtain a mixture, so that the microorganisms produce mineralization reaction on the sand; a monitoring module connected with the microorganism mineralization reaction module, for monitoring preset parameters of the mixture; the preset parameters include pH value and dissolved oxygen content; a temperature control module connected with the microorganism mineralization reaction module, for controlling the temperature inside the microorganism mineralization reaction module. The microorganism mineralization reaction module comprises: an intermittent reactor comprising a top cover and a bottom cover, the top cover being provided with a gas outlet; the intermittent reactor is used for storing sand, microorganisms and the cementing fluid obtained from the cementing fluid providing module; a second gas washing bottle connected with the gas outlet of the top cover of the intermittent reactor through a pipeline, used for absorbing water-soluble gas from the intermittent reactor through water stored in the second gas washing bottle; a stirrer used for mixing the sand, the microorganisms and the cementing fluid stored in the intermittent reactor to obtain a mixture; a liquid outlet tank used for collecting the remaining cementing fluid in the intermittent reactor; 2. The sand reinforcement test device based on the microorganism mineralization technology according to claim 1, characterized by, a second pump having one end connected with the intermittent reactor through a pump pipeline and the other end connected with the liquid outlet tank through a pump pipeline, used for pumping the remaining cementing fluid in the intermittent reactor into the liquid outlet tank. The cementing fluid providing module comprises: a liquid inlet tank used for storing cementing fluid; a gas tank connected with the liquid inlet tank through a pipeline, used for providing preset gas suitable for microorganism survival; a gas collecting bag connected with the liquid inlet tank through a pipeline, used for collecting the remaining gas in the liquid inlet tank which is not mixed into the cementing fluid; a first gas washing bottle connected on the pipeline between the gas collecting bag and the liquid inlet tank, used for absorbing water-soluble gas from the liquid inlet tank through water stored in the first gas washing bottle; 3. The sand reinforcement test device based on the microbial mineralization technology according to claim 1, characterized by, a first pump having one end connected with the liquid inlet tank through a pump pipeline and the other end connected with the microorganism mineralization reaction module through a pump pipeline, used for pumping the cementing fluid mixed with the preset gas in the liquid inlet tank into the microorganism mineralization reaction module. The monitoring module comprises: a pH probe used for collecting the pH value of the mixture; a dissolved oxygen probe used for collecting the dissolved oxygen content of the mixture; 4. The sand reinforcement test device based on the microbial mineralization technology according to claim 1, characterized by, a monitor having one end connected with the pH probe and the other end connected with the dissolved oxygen probe, used for monitoring the pH value and the dissolved oxygen content of the mixture. The temperature control module comprises: a water bath sandwich wrapped outside the intermittent reactor, used for storing constant-temperature water to keep the intermittent reactor constant-temperature; 5. The sand reinforcement test device based on the microbial mineralization technology according to claim 2, characterized by, a constant-temperature water bath tank connected with the water bath sandwich through a pipeline, used for providing constant-temperature water to the water bath sandwich. The cementing fluid providing module further comprises: an aeration head arranged at the end of the pipeline connected from the gas tank to the liquid inlet tank, used for exposing the preset gas from the gas tank into the liquid inlet tank. A three-way valve, the gas bag and the first gas washing bottle are connected to two ends of the three-way valve through silica gel pipes, and the other end of the three-way valve is connected to the top of the liquid inlet tank for controlling the flow of gas in the three-direction conduit.

6. The sand reinforcement test device based on the microorganism mineralization technology according to claim 2, characterized by, The preset gas includes nitrogen or oxygen, nitrogen is used to maintain an environment suitable for the survival of microorganisms, and oxygen is used to supplement when the dissolved oxygen content in the cementing fluid is insufficient.

7. The sand reinforcement test device based on the microbial mineralization technology according to claim 2, characterized by, The components of the cementing fluid in the liquid inlet tank include calcium chloride and urea, or calcium nitrate and sodium acetate.

8. The sand reinforcement test device based on the microbial mineralization technology according to claim 1, characterized by, The stirrer includes a motor with adjustable speed, a stirring paddle and a coupling.

9. The sand reinforcement test device based on the microbial mineralization technology according to claim 2, wherein, One end of the first pump is connected to the liquid inlet tank through a pump pipe, and the other end is connected to the bottom cover of the batch reactor through a pump pipe to pump the cementing fluid into the batch reactor. The other end of the second pump is connected to the liquid outlet tank through a pump pipe to pump the remaining cementing fluid in the batch reactor into the liquid outlet tank.

10. The sand reinforcement test device based on the microbial mineralization technology according to claim 1, wherein, The dissolved oxygen concentration of the cementing fluid provided by the cementing fluid providing module is adapted to the microorganisms.

11. The sand reinforcement test device based on the microbial mineralization technology according to claim 3, wherein, The pH probe and the dissolved oxygen probe are made of acid and alkali resistant and corrosion resistant materials.

12. The sand reinforcement test device based on the microbial mineralization technology according to claim 2, characterized by, The cementing fluid providing module further comprises: A pressure reducing valve is arranged in the conduit connecting the liquid inlet tank and the gas tank to control the flow of the preset gas transmitted from the gas tank to the liquid inlet tank through the conduit.

13. The sand reinforcement test device based on the microbial mineralization technology according to claim 2, characterized by, The cementing fluid providing module further comprises: A check valve is arranged on the pump pipe between the first pump and the microbial mineralization reaction module to control the cementing fluid pumped into the microbial mineralization reaction module.

14. The sand reinforcement test device based on the microbial mineralization technology according to claim 1, characterized by, The microbial mineralization reaction module further comprises: An output valve is arranged on the pump pipe between the batch reactor and the second pump to control the cementing fluid pumped out of the batch reactor.

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