TWI788271B - Method for cementing sand particles by using microorganisms to induce calcium carbonate precipitation - Google Patents

Abstract

A method for cementing sandy soil particles by using microorganisms to induce calcium carbonate precipitation, comprising the following steps: (1). Including mixing sorghum distiller's grains with water and performing solid-liquid separation to obtain clarified liquid, and adjusting the pH value of the clarified liquid to prepare Slightly alkaline sorghum distiller's grains medium; (2). Inoculating urease-producing microorganisms into sorghum distiller's grains medium for cultivation to prepare urease-producing microorganism treatment liquid; and (3). Including making urease-producing microorganism treatment liquid with calcium source and The cementing solution of urea undergoes microorganism-induced calcium carbonate precipitation reaction in the sand particles to cement the sand particles. The method of the present invention prepares sorghum distiller's grains medium and uses it to cultivate urease-producing microorganisms, thereby greatly reducing the cost of cultivating urease-producing microorganisms, and effectively cementing sand particles to improve mechanical properties.

Description

Method for cementing sand particles by using microorganisms to induce calcium carbonate precipitation

The invention relates to a method for solidifying sandy soil, in particular to a method for cementing sandy soil particles by using microorganisms to induce calcium carbonate precipitation.

Microbial induce calcium carbonate precipitation (MICP) is an environmentally friendly and long-lasting technology. In recent years, it has been widely used in land engineering such as soil improvement, soil liquefaction control, and dust control. Microbe-induced calcium carbonate precipitation is a microorganism that produces urease during metabolism in sandy soil, such as Sporosarcina Pasteurii, etc. The urease produced hydrolyzes urea to produce ammonium ions (NH ₄ ⁺ ) and carbonate ions ( CO ₃ ²⁻ ), carbonate ions react with calcium ions to form calcium carbonate crystals on the surface of microorganisms, and use calcium carbonate crystals to cement the original loose sand particles to improve the mechanical properties of sand without destroying The ecological environment of the soil.

In addition, the cultivation of microorganisms is deeply affected by the culture medium, and the properties of the culture medium, such as pH value, carbon source, nitrogen source, minerals, vitamins, osmotic pressure and ionic strength, are very important for the cultivation of microorganisms. Currently known media suitable for cultivating urease-producing microorganisms such as Bacillus pasteurianus include laboratory-grade medium such as Tryptone Soy Broth (TSB) and NH ₄ -YE medium, but the cost of laboratory-grade medium is expensive However, it is very unfavorable for the field application of MICP. Therefore, in recent years, quite a lot of research has focused on how to reduce the cost of the medium, including using livestock wastewater, whey wastewater, activated sludge and molasses to make the medium.

Therefore, the object of the present invention is to provide a method for cementing sand particles by using microorganisms to induce calcium carbonate precipitation.

Thus, the present invention utilizes microorganisms to induce calcium carbonate precipitation to make the method for cementing sand particles, comprising the following steps: (1). Including mixing sorghum distiller's grains with water and performing solid-liquid separation to obtain clarified liquid, and adjusting the pH value of the clarified liquid to prepare weakly alkaline sorghum distiller's grains medium; and (3). Including making the urease-producing microorganism treatment liquid and the cementing solution including calcium source and urea carry out microorganism-induced calcium carbonate precipitation reaction in the sand particles so as to cement the sand particles.

The effect of the present invention is that: the method of the present invention uses the sorghum distiller's grain medium prepared from the sorghum distiller's grains to cultivate the urease-producing microorganism, not only the preparation cost of the sorghum distiller's grain medium is low, but also the prepared urease-producing microorganism treatment liquid is cultivated The sand particles can be effectively bonded. Therefore, the method of the present invention not only effectively recycles the sorghum distiller's grains belonging to the tobacco and alcohol industry waste, greatly reduces the cost of cultivating urease-producing microorganisms, but also effectively bonds the sand particles. thereby improving the mechanical properties.

The present invention utilizes microorganisms to induce calcium carbonate precipitation to make the method for cementing sand and soil particles, comprising the following steps: (1). Including mixing sorghum distiller's grains with water and carrying out solid-liquid separation to take clarified liquid, and adjusting the pH value of the clarified liquid so that Prepare a weakly alkaline sorghum distiller's grain medium; (2). Inoculate the urease-producing microorganisms into the sorghum distiller's grains medium and cultivate them to obtain a urease-producing microorganism treatment solution; and (3). Make the urease-producing microorganism treatment solution and include The cementing solution of calcium source and urea undergoes microorganism-induced calcium carbonate precipitation reaction in the sand particles to cement the sand particles.

Herein, the "Sorghum distillery residue" refers to by-products produced during the production of sorghum liquor. The pH range of sorghum distiller's grains is about 3.5 to 5, and the organic content ranges from about 50 g/L to 150 g/L. Sorghum distiller's grains are rich in nitrogen sources required for microbial growth, and contain acids, alcohols and esters that can Provide the carbon source required for microbial growth, and contain vitamins and inorganic salts to provide the nutrient source required for microbial growth. The source of the sorghum distiller's grains used in the present invention is not particularly limited, and any sorghum distiller's grains produced by the sorghum distiller's brewing process are suitable for the present invention.

In the step (1), the specific form of the solid-liquid separation is, for example, but not limited to screen filtration, centrifugation, filter paper filtration or any combination of the above. In some specific implementation aspects of the present invention, the clarified liquid is obtained by mixing the sorghum distiller's grains with water, followed by screen filtration, centrifugal separation and filter paper filtration, and can be selected according to the actual pH value of the clarified liquid. Optionally dilute the clear solution with water before adjusting the pH. Preferably, the pH range of the sorghum distiller's grains medium is 8 to 9, and the cultured urease-producing microorganism treatment liquid has higher biomass and urease production.

In the step (2), preferably, the urease-producing microorganism is selected from Bacillus pasteurianus. Preferably, the urease-producing microorganism treatment solution has higher urease activity when the OD600 ranges from 0.8 to 1.2.

In this step (3), the operation method of making the urease-producing microorganism treatment solution and the cementing solution to carry out microorganism-induced calcium carbonate precipitation reaction in the sand particles is preferably to spray the urease on the surface of the sand particles. The urease-producing microorganism treatment liquid, and then spraying the cementing solution, can quickly generate calcium carbonate precipitation, and the microorganism-induced calcium carbonate precipitation reaction is relatively complete.

The cementing solution also includes water, and the cementing solution is formed by dissolving the urea and the carbon source in the water. Wherein, the calcium source is formed from calcium ion compounds selected from calcium chloride. Preferably, the concentration range of the urea in the cementing solution is 0.1M to 1.1M, the concentration range of the calcium source is 0.1M to 1.1M; more preferably, the concentration of the urea is 1.1M, and the calcium chloride The concentration is 1.1M, so that the effect of cementing the sand particles is better.

Preferably, the sum of the dosage volume of the urease-producing microorganism treatment liquid and the cementation solution is equal to the pore volume of the sand particles, which can make the sand particles more cemented. Preferably, the ratio of the dosage volume of the cementing solution to the dosage volume of the urease-producing microorganism treatment solution is in the range of 1:10 to 10:1, which can make the sand particles more cemented. Preferably, the microorganism-induced calcium carbonate precipitation reaction is carried out for at least 28 days, which can make the degree of cementation of the sand particles higher.

The present invention will be further described with reference to the following examples, but it should be understood that the examples are for illustrative purposes only and should not be construed as limitations on the implementation of the present invention.

[ Example 1]

Preparation of sorghum distiller's grains medium : Stir 100 g of sorghum distiller's grains (taken from the Chiayi distillery of Taiwan Tobacco and Liquor Co., Ltd., and stored at 4°C) with 300 mL of pure water, and then mix them with No. 50 Take the filtrate after removing the solids by screen filtration, then centrifuge the filtrate at 5000 rpm for 10 minutes and take the supernatant, then filter the supernatant with 7 μm filter paper to obtain a clear liquid, and then use pure water to clarify the The solution was diluted 2.5 times and then the pH value was adjusted with 1 M sodium hydroxide to obtain a sorghum distiller's grain medium with a pH value of 8 to 9. Among them, based on the purchase amount of the sorghum distiller's grains from Chiayi Distillery and the output of the sorghum distiller's grains medium, the cost per liter of the sorghum distiller's grains medium is calculated to be about NT$0.7.

Preparation of urease-producing microorganism treatment solution : put 180 mL of the sorghum distiller's grains medium into a 500 mL Erlenmeyer flask and place it in a high-temperature and high-pressure autoclave to sterilize at 121°C for 20 minutes. After sterilization, the Erlenmeyer flask was removed from the high temperature The autoclave was moved to an aseptic operating table for cooling, and when the sorghum distiller's grains medium was cooled to room temperature, 60 mL of Bacillus pasteurii bacteria liquid (Sporosarcina pasteurii, DSM33, purchased from BCRC Biological Resource Conservation and Research Center) Inoculated into the sorghum distiller's grain medium, and cultivated in an incubator at a constant temperature of 30°C and a rotational speed of 130 rpm until the OD600 value reached 0.8 to prepare a urease-producing microorganism treatment solution.

Preparation of fixed sand samples : sea sand (sampling site is the silt land of Taichung Harbor North Breakwater, the latitude and longitude coordinates (WGS84) of the sampling site are 24°31'15.68'' N, 120°52'37.95'' E, sea sand with a bulk density of 1.42 g/cm ³ and a porosity of 46.65%) were evenly spread in a plastic tray, and then, 45 mL of urease-producing microorganism treatment solution was evenly sprayed on the surface of sea sand, and then 225 mL of The cementing solution (formed by dissolving urea and calcium chloride in water, and the concentration of urea is 1.1M and the concentration of calcium chloride is 1.1M) is evenly sprayed on the surface of sea sand, and then the plastic plate is placed in a ventilated place to stand still After 28 days, let the urease-producing microorganism treatment solution and the cementing solution undergo microorganism-induced calcium carbonate precipitation reaction in the sea sand, so that the sea sand particles are cemented to prepare a fixed sand sample. Wherein, the volume of the urease-producing microorganism treatment solution+the volume of the cementing solution=the pore volume of the sea sand, and the pore volume of the sea sand=the capacity of the plastic plate×the porosity of the sea sand.

[ comparative example 1]

The difference between Comparative Example 1 and Example 1 is that in Comparative Example 1, instead of using the sorghum distiller's grains medium to prepare the urease-producing microorganism treatment liquid, 20 g of yeast extract (yeast extract, purchased from Becton, Dickinson and Company ), 10 g of ammonium sulfate (ammonium sulphate, purchased from JT Baker) and 15.748 g of Tris(hydroxymethyl)aminomethane, generally referred to as Tris] were dissolved in 1000 ml of pure water culture medium (hereinafter referred to as NH ₄ -YE medium) to cultivate urease-producing microorganisms. Among them, according to the purchase amount of yeast extract, ammonium sulfate and Tris and the output of the NH ₄ -YE medium, the cost per liter of the NH ₄ -YE medium is calculated to be about NT$214.

[ control group ]

Spread the sea sand (the sampling site is the silt land of the North Breakwater of Taichung Harbor, the latitude and longitude coordinates (WGS84) of the sampling site are 24°31'15.68'' N, 120°52'37.95'' E) on a plastic tray 450 mL of pure water was evenly sprayed on the surface of the sea sand, and then the plastic plate was placed in a ventilated place for 28 days to obtain a fixed sand sample.

[ Characteristic analysis ]

Carry out following analysis respectively to the fixed sand sample of embodiment 1, comparative example 1 and matched group:

Surface morphology analysis : Dry and platinum-plate the fixed sand sample in sequence, and then use a field emission scanning electron microscope (FE-SEM for short, manufacturer: Hitachi, model: S4800-I) to analyze the appearance of the fixed sand sample Analysis, the resulting SEM photos are shown in Figures 1 to 3.

Analysis of calcium carbonate cement structure : use a digital polarizing microscope (manufacturer: Meiji Techno, model: MS-40DR/SAM1-P) to observe whether there is a calcium carbonate cement structure formed by MICP in the fixed sand sample, and the obtained photos are shown in Figure 4 to Figure 6.

X -ray diffraction (X-ray diffraction , XRD) analysis : Utilize X-ray diffraction instrument (manufacturer: Shimadzu, model: XRD-6000) to carry out X-ray diffraction analysis on fixed sand sample, the obtained X-ray The diffraction diagram is shown in Figure 7.

Calcium carbonate content : the calcium carbonate content in the sand sample was measured according to the standard test method ASTM D4373-14, and the results are shown in Table 1.

Shear strength : reset the shear force meter (brand: Italy CONTROLS, model: 16-T0175/A) to zero and insert it into the surface of the fixed sand sample, and continue to rotate the shear force meter clockwise until the fixed sand sample The surface is broken, and the shear force value at this time represents the shear strength of the fixed sand sample, and the results are shown in Table 1. The higher the shear strength value of the fixed sand sample, the better the ability of the fixed sand sample to resist wind erosion.

Sea sand loss rate : Weigh the fixed sand sample and record it as W0, then place the fixed sand sample in a wind tunnel testing machine (assembled by the Soil and Water Conservation Department of Zhongxing University) and blow the fixed sand with a wind speed of 10 m/s After 3 minutes of sampling, weigh the fixed sand sample and record it as W1, and calculate the loss rate (%) of the fixed sand sample = (W0－W1)÷W0×100%. And the wind speeds of 15 m/s and 20 m/s were tested according to the above methods, and the results are shown in Table 1. The lower the loss rate of the fixed sand sample, the better the ability of the fixed sand sample to resist wind erosion.

[ Results and discussion ]

surface 1 the Example 1 Comparative example 1 control group cementing solution Calcium chloride concentration (M) 1.1 1.1 --- Urea concentration (M) 1.1 1.1 --- Dosage (mL) 225 225 0 Urease-producing microorganism treatment solution culture medium Sorghum distiller's grain medium NH ₄ -YE medium --- OD600 0.8 0.8 --- Dosage (mL) 45 45 0 water Dosage (mL) 0 0 450 Calcium carbonate content of the sand sample (%) 9.16 7.89 0.66 Shear strength of fixed sand samples (N/cm ² ) 0.427 0.44 0.067 Sea sand loss rate of fixed sand samples (%) Wind speed 10 m/s 0.009 0.005 0.154 Wind speed 15 m/s 0.068 0.074 29.0 Wind speed 20 m/s 0.281 0.163 62.1

Referring to Fig. 1 to Fig. 6, compare the fixed sand sample (Fig. 3 and Fig. 6) of control group, in the fixed sand sample of embodiment 1 (Fig. 1 and Fig. 4) and comparative example 1 (Fig. 2 and Fig. 5) It can be clearly observed that diamond-shaped massive calcite (Calcite) and spherical hexagonal calcite (Vaterite) grow between the sea sand particles, and the sea sand particles are cemented to form lumps.

Referring to Fig. 7, the XRD patterns of the fixed sand samples of the control group, Example 1 and Comparative Example 1 all have characteristic peaks contributed by the main component of sea sand "quartz (Quartz)", but compared with the fixed sand samples of the control group In the XRD patterns of the sand samples, in the XRD patterns of the fixed sand samples of Example 1 and Comparative Example 1, there are characteristic peaks contributed by calcite and hexagonal calcite.

Referring to Table 1, compared with the control group without MICP, both Example 1 and Comparative Example 1 can improve the shear strength of the fixed sand sample and reduce the sea sand loss rate of the fixed sand sample by performing MICP in the sea sand, and the corresponding Compared with the NH ₄ -YE medium with high cost used in Comparative Example 1, the urine-producing microorganism treatment solution obtained by culturing the low-cost sorghum distiller's grain medium in Example 1 makes the shear strength of the fixed sand sample and the loss rate of sea sand can be reduced. Equivalent to Comparative Example 1.

In summary, the method of the present invention uses sorghum distiller's grains to prepare sorghum distiller's grains medium, which can not only effectively recycle the sorghum distiller's grains that are wastes from the tobacco and alcohol industry, but also greatly reduce the cost of cultivating urease-producing microorganisms, and can effectively The sand and soil particles are cemented to improve the mechanical properties, therefore, the purpose of the present invention can indeed be achieved.

But what is described above is only an embodiment of the present invention, and should not limit the scope of the present invention. All simple equivalent changes and modifications made according to the patent scope of the present invention and the content of the patent specification are still within the scope of the present invention. Within the scope covered by the patent of the present invention.

Other features and effects of the present invention will be clearly presented in the implementation manner with reference to the drawings, wherein: Fig. 1 is the photograph of the scanning electron microscope of embodiment 1; Fig. 2 is the photograph of the scanning electron microscope of comparative example 1; Fig. 3 is the photograph of the scanning electron microscope of control group; Fig. 4 is the photo of the digital polarizing microscope of embodiment 1; Fig. 5 is the photo of the digital polarizing microscope of comparative example 1; Figure 6 is a photograph of a digital polarizing microscope of the control group; and Fig. 7 is an X-ray diffraction diagram of Example 1, Comparative Example 1 and a control group.

Claims (10)

A method for cementing sand particles by using microorganisms to induce calcium carbonate precipitation, comprising the following steps: (1). Including mixing sorghum distiller's grains with water and performing solid-liquid separation to obtain a clarified liquid, and adjusting the pH value of the clarified liquid to prepare a weakly alkaline sorghum distiller's grains medium; and (3). Including making the urease-producing microorganism treatment solution and the cementing solution including calcium source and urea carry out microorganism-induced calcium carbonate precipitation reaction in the sand particles so as to cement the sand particles. The method for cementing sandy soil particles by using microorganisms to induce calcium carbonate precipitation as described in Claim 1, wherein, in the step (1), the pH value of the sorghum distiller's grains medium is in the range of 8 to 9. The method for cementing sand particles by using microorganisms to induce calcium carbonate precipitation as described in Claim 1, wherein, in the step (2), the OD600 of the urease-producing microorganism treatment solution ranges from 0.8 to 1.2. The method for cementing sand particles by using microorganisms to induce calcium carbonate precipitation as described in Claim 1, wherein, in the step (2), the urease-producing microorganisms are selected from Bacillus pasteurianus. Utilize microorganism to induce calcium carbonate precipitation as described in claim item 1 and make sandy soil particle cementation method, wherein, in this step (3), be to spray this urease microbial treatment liquid on the surface of this sandy soil particle first, then spray the cementing solution. The method for cementing sand particles by using microorganisms to induce calcium carbonate precipitation as described in Claim 1, wherein, in the step (3), the calcium source is formed by calcium ion compounds selected from calcium chloride. The method for cementing sand particles by using microorganisms to induce calcium carbonate precipitation as described in claim 1, wherein, in the step (3), the cementing solution also includes water, and the concentration range of the urea in the cementing solution is 0.1M to 1.1M, and the concentration of the calcium source ranges from 0.1M to 1.1M. The method for cementing sand particles by using microorganisms to induce calcium carbonate precipitation as described in claim 1, wherein, in the step (3), the microorganisms induce calcium carbonate precipitation reaction for at least 28 days. Utilize microorganism to induce calcium carbonate precipitation as described in claim item 1 and make the method for cementing sand particles, wherein, in this step (3), the sum of the consumption volume of this urease-producing microorganism treatment liquid and the consumption volume of this cementation solution is equal to The pore volume of the sand particles. Utilize microorganism-induced calcium carbonate precipitation as described in claim 1 to make the method for cementing sand particles, wherein, in this step (3), the ratio range of the volume of the volume of the cementing solution to the volume of the volume of the urease-producing microorganism treatment solution 1:10 to 10:1.

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