Method for synchronously removing suspended matters and hardness ions in water based on biomineralization

Abstract

The invention provides a method for synchronously removing suspended matters and hardness ions in water based on biomineralization, which comprises the following steps: high-hardness wastewater and a pre-mineralized urease-producing bacterium liquid are mixed and cultured, the pre-mineralization is to form a calcium carbonate shell on the surface of the urease-producing bacterium, and the urease-producing bacterium can hydrolyze urea to generate carbonate ions and ammonium ions. A mineralized shell is formed through the pre-mineralization process to protect the strain, reduce the influence of pollutants in the environment on the urease activity of the strain, increase the self weight of the strain and promote co-sedimentation of thalli and suspended solids in wastewater, hardness ions in the wastewater are converted into carbonate solid minerals through biological mineralization, removal of the hardness ions is achieved, and the removal rate of the wastewater is increased. Meanwhile, heavy metals and organic pollutants in the wastewater can be removed in the biomineralization process of the urease-producing bacteria. According to the method, synchronous removal of hardness ions and suspended solids in the wastewater is realized based on a biomineralization treatment process, and the method is environment-friendly, low in cost and easy for large-scale application.

Description

Technical Field

[0001] The invention relates to a method for synchronously removing suspended matter and hardness ions in water based on biomineralization, and belongs to the technical field of sewage treatment. Background Art

[0002] In high-hardness wastewaters like oilfield produced water and coal chemical wastewater, suspended solids and hardness ions have always been key and challenging issues in wastewater pretreatment. On the one hand, water bodies often contain large amounts of suspended solids, which are highly stable and severely interfere with subsequent advanced treatments such as adsorption and membrane treatment. On the other hand, excessively high concentrations of hardness ions can easily form suspended solid impurities in the water or precipitate with anions, causing scale to clog pipelines and increase electrochemical corrosion, complicating subsequent treatment and compromising wastewater treatment effectiveness.

[0003] During the pretreatment of wastewater, the focus is on the removal of suspended solids and hardness ions. At present, the treatment of suspended solids mainly involves adding a large amount of flocculants, and multiple agents need to be used together; and the commonly used hardness removal methods (i.e., methods for removing hardness ions) include adsorption, electrochemistry, ion exchange, and agent softening. However, these methods have high limitations, such as poor treatment effect, large dosage of agents, and easy introduction of sodium ions (Na + ), chloride ion (Cl - ), sulfate ion (SO4 2- ) and other impurity ions, increasing treatment costs and making subsequent processing more difficult. Biological methods have attracted widespread attention due to their environmental friendliness and advantages over traditional wastewater treatment technologies, such as low cost and improved treatment effectiveness. They hold promising application prospects in water treatment. Biological methods utilize microbial adsorption, precipitation, and filtration mechanisms to enrich and precipitate suspended solids and hardness ions in aqueous solutions, thereby reducing suspended solids concentration and hardness in wastewater. Therefore, finding a method for efficiently and simultaneously removing suspended solids and hardness ions in wastewater using microorganisms is a continuing concern for those skilled in the art. Summary of the Invention

[0004] The present invention provides a method for simultaneously removing suspended matter and hardness ions in water based on biomineralization, which is used for pretreating high-hardness wastewater, simultaneously removing suspended matter and hardness ions in the wastewater, and reducing the difficulty of subsequent wastewater treatment.

[0005] The present invention provides a method for simultaneously removing suspended matter and hardness ions in water based on biomineralization, the method comprising the following steps:

[0006] High-hardness wastewater is mixed and cultured with a pre-mineralized urease-producing bacterial solution. The pre-mineralization is to form a calcium carbonate shell on the surface of a single urease-producing bacterium through a mineralization technology. The urease-producing bacteria can hydrolyze urea to produce carbonate ions and ammonium ions. The present invention provides a method for simultaneously removing suspended matter and hardness ions in water based on biomineralization. The urease-producing bacteria are pre-mineralized to obtain a pre-mineralized urease-producing bacterial solution, which is mixed and cultured with high-hardness wastewater. The suspended matter and hardness ions in the wastewater are simultaneously removed through the bioflocculation, biodegradation and biomineralization of the urease-producing bacteria. Figure 1 As shown. Specifically, it means that during the growth and metabolism of urease-producing bacteria, on the one hand, a mineralized shell is formed through the pre-mineralization process to provide protection for the strain (i.e., urease-producing bacteria), reduce the impact of environmental pollutants on the strain's urease activity, increase the strain's own weight, and promote the co-sedimentation of the bacteria and suspended solids in the wastewater; on the other hand, hardness ions in the wastewater are converted into carbonate solid minerals through biomineralization, thereby achieving the removal of hardness ions. At the same time, the biomineralization process of urease-producing bacteria can also achieve the removal of heavy metals and organic pollutants in the wastewater. This method is based on the simultaneous removal of hardness ions and suspended solids in wastewater during the biomineralization treatment process, and the method is environmentally friendly, low-cost, and easy to apply on a large scale.

[0007] In a specific embodiment, the urease-producing bacteria should have urease activity. The urease activity is determined by culturing the microorganism in a culture medium containing urea and an indicator phenol red and observing the color change of the culture medium. When the urease-producing bacteria have urease activity, the indicator phenol red turns pink under alkaline conditions. As the urease-producing microorganism grows, the urease produced decomposes urea to produce carbonate ions (CO3 2- ) and ammonium ions (NH4 + ), making the culture medium alkaline as a whole, and the indicator phenol red makes the culture medium pink. The reaction process involved is shown in Formula 1:

[0008] Formula 1.

[0009] Through the above screening method, the urease-producing bacteria screened out in the present invention are one or two or more urease-producing bacteria selected from the group consisting of Staphylococcus Succinus, Stenotrophomonas Pavanii, and Lysinibacillus Fusiformis.

[0010] Specifically, the urease-producing bacteria Staphylococcus Succinus is deposited in the China Industrial Microorganism Culture Collection Center with a deposit number of CICC 24360; the urease-producing bacteria Stenotrophomonas Pavanii is deposited in the China Agricultural Microorganism Culture Collection Center with a deposit number of ACCC 19499; and the urease-producing bacteria Lysinibacillus Fusiformis is deposited in the China Agricultural Microorganism Culture Collection Center with a deposit number of ACCC60107.

[0011] Subsequently, the urease-producing bacteria are pre-mineralized, and a calcium carbonate shell is formed on the surface of a single urease-producing bacterium through a mineralization technique to prepare a pre-mineralized urease-producing bacterial solution. The specific preparation method of the pre-mineralized urease-producing bacterial solution comprises the following steps:

[0012] After the urease-producing bacteria are expanded (or amplified) and cultured, the bacterial cell precipitate is collected by centrifugation, and the obtained bacteria are placed in a calcium chloride (CaCl2) solution for incubation, and calcium ions are adsorbed on the surface of the bacteria; unbound calcium ions are removed to obtain a mixed system; a carbonate ion solution is added to the mixed system, and the obtained solution is centrifuged to collect the bacterial cell precipitate, which is then resuspended to obtain the pre-mineralized urease-producing bacterial solution.

[0013] Furthermore, the bacteria are placed in a CaCl2 solution with a concentration of 10-20 mmol / L and incubated under the condition of pH = 7.0-7.4. Specifically, the aforementioned pH can be 7.0, 7.1, 7.2, 7.3, 7.4 or a range consisting of any two thereof, and the concentration of the CaCl2 solution (i.e., the CaCl2 concentration in the CaCl2 solution) can be 10 mmol / L, 13 mmol / L, 15 mmol / L, 18 mmol / L, 20 mmol / L or a range consisting of any two thereof.

[0014] Furthermore, the process of adding carbonate ion solution to the mixed system includes: adding sodium carbonate (Na2CO3) solution to the mixed system until the pH of the resulting solution is 8-10, for example, 8, 8.5, 9, 9.5, 10 or a range consisting of any two thereof, preferably 9.

[0015] Furthermore, in the pre-mineralized urease-producing bacterial solution, the concentration of the pre-mineralized urease-producing bacterial strain is 7×10 8 -9×10 10 cells / mL, for example 7×10 10 cells / mL、7.5×10 10 cells / mL、8×10 10 cells / mL、8.5×1010 cells / mL、9×10 10 cells / mL or a range consisting of any two of them.

[0016] In one embodiment, the urease-producing bacteria are inoculated on a solid culture medium and placed in a constant temperature incubator at a temperature of 20°C-30°C for amplification culture. The urease-producing bacteria grown on the solid culture medium are dipped into a liquid culture medium and cultured on a shaking platform. When the strain concentration in the liquid culture medium reaches 7×10 8 -9×10 10 cells / mL, the bacterial cell precipitate was collected by centrifugation, and the obtained bacterial cells were placed in a CaCl2 solution with a concentration of 10-20 mmol / L and incubated overnight at a pH of 7.0-7.4 to allow calcium ions to be fully adsorbed on the bacterial surface. Unbound calcium ions were removed by stirring and dialysis in physiological saline to obtain a mixed system; the mixed system (i.e., the liquid after dialysis treatment) was placed in a stirrer and a Na2CO3 solution with a concentration of 10-20 mmol / L was added dropwise until the pH of the obtained solution was 9; the final solution (i.e., the obtained solution) was centrifuged to collect the bacterial cell precipitate, and resuspended in physiological saline to obtain the pre-mineralized urease-producing bacterial culture liquid, in which the concentration of the pre-mineralized urease-producing bacterial strain was 7×10 8 -9×10 10 cells / mL.

[0017] Specifically, the temperature of the constant temperature incubator can be 20°C, 23°C, 25°C, 28°C, 30°C or a range consisting of any two thereof, and the concentration of the Na2CO3 solution can be 10mmol / L, 13mmol / L, 15mmol / L, 18mmol / L, 20mmol / L or a range consisting of any two thereof.

[0018] The solid culture medium, liquid culture medium and culture vessel used in the above method can all be conventional culture medium and culture vessel in the art. Considering the culture effect on urease-producing bacteria, the solid culture medium and liquid culture medium for culturing urease-producing bacteria can be one or more of LB (Luria-Bertani) medium, broth peptone medium, and potato sucrose medium; the culture vessel for the solid culture medium is a flat culture dish, and the culture vessel for the liquid culture medium is a triangular culture flask.

[0019] Considering that LB medium is a widely used bacterial culture medium with a simple preparation method, it is generally used to pre-culture bacteria to enable rapid growth and exponential amplification of bacteria to meet the usage requirements in quantity. Commonly used liquid LB medium includes tryptone, yeast extract and sodium chloride (NaCl). Solid LB medium can be prepared by adding agar to the above materials.

[0020] The amplification culture time can be determined according to the growth conditions of bacteria and fungi. Generally, the amplification culture time of urease-producing bacteria in solid culture medium is 24-36 h, for example, 24 h, 25 h, 28 h, 30 h, 32 h, 35 h, 36 h or a range consisting of any two of them.

[0021] After the amplification culture is completed, the urease-producing bacteria grown on the solid culture medium are transferred to a liquid culture medium for shaking culture. The shaking culture conditions are as follows: a temperature of 25°C-37°C, for example, 25°C, 28°C, 30°C, 33°C, 35°C, 37°C or a range consisting of any two thereof, and a rotation speed of 120-150 r / min, for example, 120 r / min, 130 r / min, 140 r / min, 150 r / min or a range consisting of any two thereof.

[0022] The culture process of urease-producing bacteria involved in the present invention is all carried out in a highly clean environment, such as a clean bench.

[0023] The prepared pre-mineralized urease-producing bacterial liquid is mixed with high-hardness wastewater for culture, and the volume ratio of the pre-mineralized urease-producing bacterial liquid to the high-hardness wastewater is 2:100-20:100, for example, 2:100, 5:100, 10:100, 15:100, 20:100 or a range consisting of any two of them.

[0024] High-hardness wastewater also includes urea, which is necessary for the production of urease-producing bacteria. Specifically, when the original wastewater does not contain urea, urea can be added to the original wastewater before mixed culture to produce the high-hardness wastewater. For example, the original wastewater includes oilfield produced water, and the high-hardness wastewater includes oilfield produced water containing urea.

[0025] Preferably, the concentration of urea in the high hardness wastewater is 5-20 g / L, for example, 5 g / L, 10 g / L, 15 g / L, 20 g / L or a range consisting of any two thereof.

[0026] High-hardness wastewater may also contain nutrients necessary for the growth of urease-producing bacteria. Specifically, the high-hardness wastewater itself may contain nutrients necessary for the growth of urease-producing bacteria. Alternatively, if the concentration of nutrients necessary for the growth of urease-producing bacteria in the high-hardness wastewater is low, additional nutrients necessary for the growth of urease-producing bacteria may be added to the high-hardness wastewater prior to mixed culture. These nutrients include one or more of peptone, yeast extract, glucose, and malt extract. Specifically, the concentration of peptone in high hardness wastewater is 4-10 g / L, for example, 4 g / L, 5 g / L, 6 g / L, 7 g / L, 8 g / L, 9 g / L, 10 g / L or a range consisting of any two of them; the concentration of yeast extract in high hardness wastewater is 2-5 g / L, for example, 2 g / L, 2.5 g / L, 3 g / L, 4 g / L, 5 g / L or a range consisting of any two of them; the concentration of glucose in high hardness wastewater is 8-20 g / L, for example, 8 g / L, 10 g / L, 13 g / L, 15 g / L, 18 g / L, 20 g / L or a range consisting of any two of them; the concentration of malt extract in high hardness wastewater is 6-10 mg / L, for example, 6 mg / L, 7 mg / L, 8 mg / L, 9 mg / L, 10 mg / L or a range consisting of any two of them.

[0027] Finally, the high-hardness organic wastewater is mixed and cultured with the pre-mineralized urease-producing bacterial solution. The mixed culture temperature is 25°C-37°C, for example, 25°C, 28°C, 30°C, 33°C, 35°C, 37°C or a range consisting of any two thereof, and the mixed culture time is 48-72 h, for example, 48 h, 54 h, 60 h, 66 h, 72 h or a range consisting of any two thereof.

[0028] The present invention provides a method for synchronously removing suspended matter and hardness ions in water based on biomineralization, and realizes the synchronous removal of suspended matter and hardness ions in wastewater through the bioflocculation and biomineralization of urease-producing bacteria. Specifically, it means that during the growth and metabolism of urease-producing bacteria, on the one hand, a mineralized shell is formed through a pre-mineralization process to provide protection for the strain, reduce the influence of environmental pollutants on the urease activity of the strain, increase the weight of the strain itself, and promote the co-sedimentation of the bacteria and suspended matter in the wastewater; on the other hand, the hardness ions in the wastewater are converted into carbonate solid minerals through biomineralization, thereby realizing the removal of hardness ions. At the same time, the biomineralization process of urease-producing bacteria can also realize the removal of heavy metals and organic pollutants in the wastewater. The method realizes the synchronous removal of hardness ions and suspended matter in wastewater based on the biomineralization treatment process, and the method is environmentally friendly, low-cost and easy to apply on a large scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1A schematic flow chart of a method for simultaneously removing suspended solids and hardness ions in water based on biomineralization according to one embodiment of the present invention;

[0030] Figure 2 This is a graph of the flocculation and sedimentation efficiency of oilfield produced water at different concentrations in Examples 2-4 (the horizontal axis is time, and the vertical axis is self-flocculation efficiency);

[0031] Figure 3 The graph of residual calcium ion content of oilfield produced water with different concentrations in Example 2-4 (the horizontal axis is time, the vertical axis is the concentration of calcium ion) 2+ ));

[0032] Figure 4 The graph of residual magnesium ion content of oilfield produced water with different concentrations in Example 2-4 (the horizontal axis is time, the vertical axis is the concentration of magnesium ion) 2+ ));

[0033] Figure 5 This is a graph showing the flocculation and sedimentation efficiency of two different pre-mineralized urease-producing bacteria on suspended solids in oilfield produced water in Examples 7-8 (the abscissa is time, and the ordinate is self-flocculation efficiency);

[0034] Figure 6 The graph of the residual calcium ion content of oilfield produced water during the cultivation of two different pre-mineralized urease-producing bacteria in Examples 7-8 (the horizontal axis is time, the vertical axis is the concentration of calcium ion 2+ )). DETAILED DESCRIPTION

[0035] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0036] In the following examples, unless otherwise specified, each step can be completed by following conventional procedures in the art, and various instruments and reagents used in each step can be purchased commercially or prepared by conventional methods.

[0037] In the following examples, the culture medium and preparation method used for microbial culture are as follows:

[0038] LB (Luria-Bertani) solid medium

[0039] Weigh 10 g of tryptone, 5 g of yeast extract, 10 g of sodium chloride (NaCl), and 18 g of agar powder, dissolve them in 1000 mL of ultrapure water, then adjust the pH to about 7 with NaOH solution. Sterilize the culture medium in a high-pressure steam autoclave at 0.1 MPa and 121°C for 25 min to obtain the culture medium. Pour the culture medium into a flat plate culture dish in an ultra-clean workbench before it solidifies, and use it for later use to obtain LB solid culture medium.

[0040] LB (Luria-Bertani) liquid medium

[0041] Weigh 10 g of tryptone, 5 g of yeast extract, and 10 g of sodium chloride (NaCl), dissolve them in 1000 mL of ultrapure water, then adjust the pH to about 7 with NaOH solution. Sterilize in a high-pressure steam autoclave at 0.1 MPa and 121°C for 25 min to obtain a mixed solution. Pour an appropriate amount of the mixed solution into a triangular flask in an ultra-clean workbench for later use to obtain LB liquid culture medium.

[0042] Example 1

[0043] This embodiment proposes a method for simultaneously removing suspended solids and hardness ions in water based on biomineralization, which specifically includes the following steps:

[0044] The urease-producing bacteria Staphylococcus Succinus (strain number CICC 24360) was used as the strain, inoculated on LB solid medium, and placed in a constant temperature incubator at 25°C for amplification culture. The urease-producing bacteria Staphylococcus Succinus growing on LB solid medium was transferred to LB liquid medium and cultured on a shaking platform. When the strain concentration in the liquid medium reached 7×10 8 -9×10 10After the mixture reached a pH of 9, the cell pellet was collected by centrifugation and incubated overnight in a 10 mmol / L CaCl2 solution at a pH of 7.0-7.4 to allow calcium ions to be fully adsorbed on the cell surface. Unbound calcium ions were removed by stirring and dialysis in normal saline to obtain a mixed system. The mixed system (i.e., the dialyzed liquid) was placed in a blender and a 10 mmol / L Na2CO3 solution was added dropwise until the pH of the resulting solution reached 9. The resulting solution was centrifuged to collect the cell pellet and resuspended in normal saline to prepare a pre-mineralized urease-producing Staphylococcus Succinus bacterial solution. The concentration of the pre-mineralized urease-producing bacterial strain was 7×10 8 -9×10 10 cells / mL.

[0045] Example 2

[0046] The oilfield produced water was used as the experimental wastewater. The pre-mineralized urease-producing bacteria Staphylococcus Succinus obtained in Example 1 was mixed with the experimental wastewater to study the removal effect of urease-producing bacteria Staphylococcus Succinus on suspended solids and hardness ions in the oilfield produced water. First, the oilfield produced water was analyzed for water quality. The test indicators mainly included pH value, chemical oxygen demand (COD), oil content, suspended solids, Ca 2+ Mg 2+ The measurement results are shown in Table 1:

[0047] Table 1

[0048]

[0049] From the data analysis in Table 1, it can be seen that the produced water sample of the oil field is neutral, the COD and oil content are high, respectively 17950 mg / L and 865.43 mg / L, the suspended solids content is 82 mg / L, and the produced water of the oil field contains a large amount of Ca 2+ (2913.595mg / L), Mg 2+ (294.464 mg / L), which is prone to scaling during treatment and can cause pipe blockage. Therefore, oilfield produced water needs to be treated to reduce the content of hardness ions and suspended solids in it to minimize damage to the formation and the possibility of oil well blockage during the reuse process of oilfield produced water.

[0050] The produced water (i.e. raw water PW, i.e. produced water with a raw water content of 100% (V / V)) does not need to be pretreated. It is diluted with deionized water by 4 times and 2 times, respectively, to prepare produced water with a raw water content of 25% (V / V) and 50% (V / V), respectively. Figure 2 、 Figure 3 、 Figure 4 and Figure 6 The 25% PW in the figure refers to produced water with a raw water content of 25% (V / V), and the 50% PW refers to produced water with a raw water content of 50% (V / V). The treatment effect of pre-mineralized urease-producing bacteria on these different concentrations of produced water was investigated. For example, the "raw water content of 25% (V / V)" in the produced water with a raw water content of 25% (V / V) refers to the volume ratio of the undiluted produced water (PW) to the diluted produced water (i.e., produced water with a raw water content of 25% (V / V)).

[0051] Nutrients were added to the above-mentioned produced water of different concentrations to facilitate the normal growth of urease-producing bacteria. The nutrients used for culturing urease-producing bacteria were peptone and yeast extract, with concentrations of 5 g / L and 2.5 g / L, respectively. In addition, urea was also added to the above-mentioned produced water of oil field to facilitate the hydrolysis of urease produced by urease-producing bacteria, with a urea concentration of 5 g / L.

[0052] In this example, the experiment was conducted using oilfield produced water with a raw water content of 25% (v / v). 2 mL of the premineralized urease-producing bacterial culture obtained in Example 1 was transferred to 100 mL of oilfield produced water with a raw water content of 25% (v / v). Mixed culture (shaker culture) was performed at 37°C and 125 rpm for 48 hours. Every two hours, the strain was allowed to settle, and the flocculation efficiency and calcium and magnesium ion contents were measured.

[0053] Example 3

[0054] The method is basically the same as Example 2, except that the concentration of oilfield produced water is replaced with 50% (V / V) of the raw water content.

[0055] Example 4

[0056] The same as Example 2, except that the concentration of oilfield produced water is replaced by 100% of the original water content (V / V) ( Figure 2 、 Figure 3 、 Figure 4 and Figure 6 The 100% PW in the figure is the produced water with a raw water content of 100% (V / V).

[0057] Figure 2 The flocculation and sedimentation efficiency of suspended solids by pre-mineralized urease-producing bacteria Staphylococcus Succinus in three different concentrations of oilfield produced water in Examples 2-4 of the present invention is shown in Figure 2-4. Figure 2In the experiment, there was no significant difference in the flocculation efficiency of the pre-mineralized urease-producing bacteria Staphylococcus Succinus on suspended solids in three different concentrations of oilfield produced water, and the flocculation efficiency was as high as 85%.

[0058] Figure 3 The residual calcium ion content of oilfield produced water changes with time during the cultivation of pre-mineralized urease-producing bacteria Staphylococcus Succinus in three different concentrations of oilfield produced water in Examples 2-4 of the present invention. Figure 3 In the experiment, the pre-mineralized urease-producing bacteria Staphylococcus Succinus achieved a calcium ion removal rate of more than 90% in three different concentrations of oilfield produced water, among which the calcium ion removal rate in produced water with a raw water content of 100% (V / V) was 90.77%; the calcium ion removal rate in produced water with a raw water content of 50% (V / V) was 93.80%; and the calcium ion removal rate in produced water with a raw water content of 25% (V / V) was 93.85%.

[0059] Figure 4 The changes in the residual magnesium ion content of oilfield produced water over time during the cultivation of pre-mineralized urease-producing bacteria Staphylococcus Succinus in three different concentrations of oilfield produced water in Examples 2-4 of the present invention are shown in FIG. Figure 3 Compared with calcium ions, the removal efficiency of magnesium ions is relatively low, and the magnesium ion removal rate decreases with the increase of oilfield produced water concentration. The magnesium ion removal rates of produced water with raw water content of 100% (V / V), 50% (V / V), and 25% (V / V) are 21.42%, 27.02%, and 47.94%, respectively. However, in chemical wastewater such as oilfield produced water, the concentration of Ca in wastewater is relatively low. 2+ The concentration will be much higher than Mg 2+ concentration, Ca 2 + As the main hardness ion, it can reduce the risk of scaling and clogging caused by hardness ions and reduce the Ca content in oilfield produced water. 2+ Concentration is more critical.

[0060] Example 5

[0061] Using oilfield produced water with a raw water content of 100% (V / V) before and after treatment in Example 4, the changes in COD and oil content of the oilfield produced water with a raw water content of 100% (V / V) before and after treatment were measured. The measurement results are shown in Table 2:

[0062] Table 2

[0063]

[0064] From the data analysis in Table 2, it can be seen that after the pre-mineralized urease-producing bacteria Staphylococcus Succinus were inoculated and cultured in the oilfield produced water with a high concentration of raw water content of 100% (V / V), the COD and oil content of the oilfield produced water were significantly reduced, with the COD removal rate being 38.72% and the oil removal rate being 50.17%. That is, the pre-mineralized urease-producing bacteria Staphylococcus Succinus can simultaneously remove some organic pollutants during the biomineralization and flocculation process.

[0065] Example 6

[0066] Using oilfield produced water with a raw water content of 100% (V / V) before and after treatment in Example 4, the changes in heavy metal content in the oilfield produced water with a raw water content of 100% (V / V) before and after treatment were measured. The measurement results are shown in Table 3:

[0067] Table 3

[0068]

[0069] ND: Non-Detect (ND means "not detected", which means it is below the detection limit of the instrument and is not detected by the instrument).

[0070] From the data analysis in Table 3, it can be seen that the treatment of oilfield produced water with pre-mineralized urease-producing bacteria Staphylococcus Succinus can significantly reduce the concentration of heavy metals. During the biomineralization process, the carbonate ions produced by the hydrolysis of urea by urease can not only fix calcium and magnesium ions, but also have a high removal effect on heavy metal ions.

[0071] Example 7

[0072] The urease-producing bacteria Stenotrophomonas Pavanii (strain number ACCC 19499) was used as the strain, inoculated on LB solid medium, and placed in a constant temperature incubator at 25°C for amplification culture. The urease-producing bacteria Stenotrophomonas Pavanii grown on LB solid medium was transferred to LB liquid medium and cultured on a shaking platform. When the strain concentration in the liquid medium reached 7×10 8 -9×10 10After the cell pellet reached 10 mmol / L cells / mL, the cells were collected by centrifugation and incubated overnight in a 10 mmol / L CaCl2 solution at pH 7.0-7.4 to allow calcium ions to be fully adsorbed on the cell surface. Unbound calcium ions were removed by stirring and dialysis in normal saline. The resulting mixed system (i.e., the dialyzed liquid) was placed in a blender and a 10 mmol / L Na2CO3 solution was added dropwise until the solution pH reached 9. The resulting solution was centrifuged to collect the cell pellet and resuspended in normal saline to prepare a pre-mineralized urease-producing bacterial solution of Stenotrophomonas Pavanii. The concentration of the pre-mineralized urease-producing bacterial strain was 7×10 8 -9×10 10 cells / mL.

[0073] In this example, the experiment used oilfield produced water with a raw water content of 100% (v / v). 2 mL of the premineralized urease-producing bacteria, Stenotrophomonas Pavanii, was transferred to 100 mL of oilfield produced water with a raw water content of 100% (v / v). The culture was mixed (shaker incubation) at 37°C and 125 rpm for 48 hours. Every two hours, the strain was allowed to settle, and the flocculation efficiency and calcium ion content were measured.

[0074] Example 8

[0075] The urease-producing bacteria Lysinibacillus Fusiformis (strain number ACCC 60107) was used as the strain, inoculated on LB solid medium, and placed in a constant temperature incubator at 25°C for amplification culture. The urease-producing bacteria Lysinibacillus Fusiformis growing on LB solid medium was transferred to LB liquid medium and cultured on a shaking platform until the strain concentration reached 7×10 8 -9×10 10 After the cell pellet reached 100 cells / mL, the cells were collected by centrifugation and incubated overnight in a 10 mmol / L CaCl2 solution at pH 7.0-7.4 to allow calcium ions to be fully adsorbed on the cell surface. Unbound calcium ions were removed by stirring and dialysis in normal saline. The resulting mixed system (i.e., the dialyzed liquid) was placed in a blender and a 10 mmol / L Na2CO3 solution was added dropwise until the solution pH reached 9. The resulting solution was centrifuged to collect the cell pellet and resuspended in normal saline to prepare a pre-mineralized urease-producing Lysinibacillus Fusiformis bacterial solution. The concentration of the pre-mineralized urease-producing bacterial strain was 7×10 8 -9×1010 cells / mL.

[0076] In this example, the experiment used oilfield produced water with a raw water content of 100% (v / v). 2 mL of the premineralized urease-producing bacterium, Lysinibacillus fusiformis, was transferred to 100 mL of oilfield produced water with a raw water content of 100% (v / v). The culture was mixed and incubated (shaker incubation) at 37°C and 125 rpm for 48 hours. Every two hours, the strain was allowed to settle, and the flocculation efficiency and calcium ion content were measured.

[0077] Figure 5 The flocculation and sedimentation efficiency of two different pre-mineralized urease-producing bacteria on suspended matter in oilfield produced water with a raw water content of 100% (V / V) in Example 7-8 of the present invention is shown in FIG. Figure 5 In the experiment, the flocculation efficiency of two different pre-mineralized urease-producing bacteria on suspended solids in oilfield produced water with a raw water content of 100% (V / V) was as high as 90%.

[0078] Figure 6 The present invention shows that the residual calcium ion content of oilfield produced water changes with time during the cultivation of two different pre-mineralized urease-producing bacteria in oilfield produced water with a raw water content of 100% (V / V) in Example 7-8. Figure 6 Among them, the calcium ion removal rates of two different pre-mineralized urease-producing bacteria in oilfield produced water with a raw water content of 100% (V / V) both reached more than 90%, among which the calcium ion removal rate of the pre-mineralized urease-producing bacteria Stenotrophomonas Pavanii was 92.48%; the calcium ion removal rate of the pre-mineralized urease-producing bacteria Lysinibacillus Fusiformis was 91.45%.

[0079] In summary, the present invention proposes a method for simultaneously removing suspended matter and hardness ions in water based on biomineralization, which has a high removal rate for suspended matter and hardness ions in wastewater, and can also remove some organic pollutants and heavy metals.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for simultaneously removing suspended solids and hardness ions in water based on biomineralization, characterized in that: The method comprises the following steps: High-hardness wastewater is mixed with pre-mineralized urease-producing bacteria liquid for culture. The pre-mineralization is to form a calcium carbonate shell on the surface of the urease-producing bacteria. The urease-producing bacteria can hydrolyze urea to generate carbonate ions and ammonium ions.

2. The method according to claim 1, characterized in that The urease-producing bacteria is Staphylococcus Succinus, which is deposited in the China Industrial Microbiological Culture Collection Center with a deposit number of CICC 24360. and / or, The urease-producing bacteria is Stenotrophomonas Pavanii, which is deposited in the China Agricultural Microbial Culture Collection Center with a deposit number of ACCC19499. and / or, The urease-producing bacteria is the urease-producing bacteria Lysinibacillus Fusiformis, which is deposited in the China Agricultural Microbiological Culture Collection Center with a deposit number of ACCC60107.

3. The method according to claim 1, characterized in that The high-hardness wastewater also contains urea necessary for the growth of urease-producing bacteria; preferably, the concentration of urea in the high-hardness wastewater is 5 g / L 20 g / L.

4. The method according to claim 1, wherein The high-hardness wastewater also includes nutrients necessary for the growth of the urease-producing bacteria.

5. The method according to claim 1, characterized in that The temperature of the mixed culture is 25°C 37℃.

6. The method according to claim 1, characterized in that The time for mixing the high-hardness organic wastewater and the pre-mineralized urease-producing bacterial solution is 48 72 hours.

7. The method according to claim 1, characterized in that After the urease-producing bacteria are expanded and cultured, the bacterial cell precipitate is collected by centrifugation, and the obtained bacteria are placed in a CaCl2 solution for incubation, and calcium ions are adsorbed on the surface of the bacteria; unbound calcium ions are removed to obtain a mixed system; a carbonate ion solution is added to the mixed system, and the obtained solution is centrifuged to collect the bacterial cell precipitate, which is then resuspended to obtain the pre-mineralized urease-producing bacterial solution.

8. The method according to claim 7, characterized in that pH=7.0 7.4, the cells were placed in a concentration of 10 Incubate in 20 mmol / L CaCl2 solution.

9. The method according to claim 7, characterized in that The process of adding carbonate ion solution to the mixed system includes: adding Na2CO3 solution to the mixed system until the pH of the obtained solution is 8 10, preferably 9.

10. The method according to claim 7, characterized in that In the pre-mineralized urease-producing bacterial solution, the concentration of the pre-mineralized urease-producing bacterial strain is 7×10 8 9×10 10 cells / mL.

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