A method for producing a microbially synthesized blue iron ore based on mechanical stirring to generate piezoelectricity
By using mechanical stirring to generate a piezoelectric effect to promote the microbial synthesis of lapis lazuli, and by utilizing the synergistic effect of piezoelectric materials and mechanical force, the problems of slow reaction, low efficiency and unstable yield in the microbial synthesis method are solved, and efficient and low-cost lapis lazuli synthesis is achieved, which is suitable for wastewater treatment and phosphorus resource recovery.
Patent Information
- Application Number
- CN202611551842.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-10-09
- Publication Date
- 2026-11-03
AI Technical Summary
Existing methods for synthesizing vivianite by microorganisms suffer from slow reaction rates, low efficiency, high costs, and unstable yields. Furthermore, their reliance on organic carbon sources may introduce secondary pollution.
The piezoelectric effect is generated by mechanical stirring. A hybrid is formed by co-culturing piezoelectric materials with microorganisms. Mechanical force is used to promote the transfer of piezoelectric electrons, driving Fe(III) to be reduced to Fe(II) and combined with phosphate to form minerals. Holes are quenched by organic matter in wastewater, thus achieving the efficient synthesis of lapis lazuli.
It significantly improves the formation rate and yield of vivianite, reduces production costs, is easy to operate, has a wide range of applications, and has good economic practicality and environmental friendliness. The reaction cycle is shortened, and the product has high purity and crystallinity.
Smart Images
Figure CN123027290A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of wastewater treatment technology, and in particular to a method for promoting the synthesis of lapis lazuli by microorganisms based on piezoelectricity generated by mechanical stirring. Background Technology
[0002] Azurite is an iron phosphate mineral with a unique crystal structure and physicochemical properties, showing great application potential in environmental pollution remediation (especially the simultaneous fixation of phosphorus and heavy metals), slow-release fertilizers in agriculture, and novel functional materials. Currently, the synthesis methods for lavrite are mainly divided into two categories. The first is chemical synthesis, which involves mixing and reacting soluble ferrous salts with phosphate solutions under strictly controlled pH, temperature, and anaerobic conditions. While this method can directly obtain lavrite, it often requires precise stoichiometry and a strictly controlled anaerobic environment, resulting in high costs and the potential generation of iron-phosphorus compound impurities. The second method is microbial synthesis, which utilizes specific microorganisms (such as dissimilatory metal-reducing bacteria) to reduce Fe(III) to Fe(II) during anaerobic respiration, which then combines with phosphates in the environment to form lavrite.
[0003] Compared to traditional chemical synthesis methods, microbial synthesis of vivianite has attracted significant attention due to its mild conditions, environmental friendliness, and low energy consumption. Currently, this process mainly relies on specific microorganisms (such as iron-reducing bacteria) to conduct enzymatic reactions under anaerobic conditions, utilizing organic carbon sources as electron donors. However, this traditional biosynthetic model has significant limitations: firstly, the reaction rate is severely limited by the metabolic activity and growth cycle of the microorganisms themselves, resulting in low synthesis efficiency and long cycles; secondly, the process depends on the continuous addition of organic substrates as an energy source, increasing costs and potentially introducing secondary pollution; and thirdly, microbial activity is easily affected by fluctuations in environmental conditions, making it difficult to control product yield and stability. Therefore, developing a new strategy that can overcome the metabolic limitations of microorganisms and efficiently drive the biosynthesis of vivianite has become a key issue that urgently needs to be addressed in this field.
[0004] Mechanical force, as a widely available and readily accessible form of physical energy, has been applied in fields such as materials synthesis, catalysis, and cell disruption. Various forms of mechanical energy are prevalent in industrial environments, such as equipment vibration, fluid turbulence, wind force, or soil stress. This energy is often not effectively utilized in traditional production processes and is even dissipated as waste energy.
[0005] It should be noted that the information disclosed in the background section above is only for understanding the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention
[0006] The main objective of this invention is to overcome the deficiencies in the aforementioned background technology and provide a method for promoting microbial synthesis of lapis lazuli based on piezoelectricity generated by mechanical stirring.
[0007] To achieve the above objectives, the present invention adopts the following technical solution: A method for promoting microbial synthesis of vivianite based on piezoelectricity generated by mechanical stirring includes the following steps: S1. Provide inoculum solution; S2. Co-culture bacteria with piezoelectric materials to generate bacteria-material hybrids; S3. The bacteria-material hybrid is inoculated into wastewater containing iron and phosphorus components. Mechanical force is applied to cause the piezoelectric material to generate piezoelectric electrons and holes. The piezoelectric electrons are transferred to the bacteria and participate in the extracellular electron transport chain, driving Fe(III) to be reduced to Fe(II) and combined with phosphate to form minerals. The holes are quenched by organic matter in the wastewater. S4. Solid-liquid separation yields lapis lazuli.
[0008] Further, in step S2, the bacteria-material hybrid is a composite structure formed by piezoelectric material particles attaching to the surface of the bacterial cell through extracellular polymer bridging; the particle size of the piezoelectric material particles is 0.1 to 50 μm.
[0009] Further, in step S2, the criteria for determining the formation of the bacterial-material hybrid are: scanning electron microscopy shows that the piezoelectric material particles are stably attached to the surface of the bacterial cell, and the zeta potential of the hybrid is at least 10mV different from that of the pure bacterial cell or the pure material.
[0010] Furthermore, in step S2, the piezoelectric material includes quartz, tourmaline, or barium titanate.
[0011] Further, in step S3, the piezoelectric electrons are transferred to the bacterial cells via direct and / or indirect pathways: the direct pathway involves electrons contacting the interface between the piezoelectric material surface and the extracellular polymeric polymer of the bacterial cells, transferring to the active sites of electron transport proteins on the outer membrane of the bacterial cells, and then entering the cell via the extracellular electron transport chain to participate in the reduction of Fe(III); the indirect pathway involves electrons first reducing Fe³⁺ in the system. + / Fe² + The redox medium is then transferred to the microorganisms through a mediator cycle.
[0012] Furthermore, in step S3, the cavities are quenched by an oxidation reaction with organic matter in the wastewater, including humic acid, fulvic acid, and / or alcohols.
[0013] Furthermore, in step S3, the mechanical force originates from external stirring force, water flow, wind force, or tidal fluctuations.
[0014] Further, in step S3, the wastewater comprises: sodium lactate 30-35 mmol / L, hydrated iron oxide 10-15 mmol / L, sodium dihydrogen phosphate 5-8 mmol / L, sodium bicarbonate 30-50 mmol / L, and ammonium chloride 2-5 mmol / L.
[0015] Furthermore, in step S3, the mechanical force is applied under the following conditions: temperature 25–30°C, rotation speed 150–200 rpm, and reaction time 3–8 days.
[0016] Furthermore, in step S4, the solid-liquid separation is achieved by natural sedimentation, with a sedimentation time of 3 to 5 hours.
[0017] The present invention has the following beneficial effects: This invention provides a method for promoting microbial synthesis of vivianite based on piezoelectricity generated by mechanical stirring, effectively overcoming the technical bottlenecks of existing biosynthetic methods, such as long reaction cycles, low synthesis efficiency, and poor product stability. This method involves adding piezoelectric materials to a wastewater treatment system and applying external mechanical force. Utilizing the piezoelectric effect, low-grade mechanical energy widely present in the environment (such as stirring force, water flow, wind force, or tidal fluctuations) is directly converted into electrical energy usable by microorganisms, constructing a coupled system of "mechanical force-piezoelectric effect-biosynthesis." This significantly promotes the formation rate and yield of vivianite without the need for additional chemical reagents or large amounts of electrical energy consumption. The method is simple to operate, has low production costs, and a wide range of applications, exhibiting good economic practicality and environmental friendliness.
[0018] This invention clarifies the electron transport pathway and hole management mechanism of piezoelectric effect-driven biomineralization, ensuring the efficient and stable operation of the coupled system. Specifically, piezoelectric electrons generated by the piezoelectric material under mechanical force are transferred to the active sites of electron transport proteins such as cytochrome c on the bacterial outer membrane through interfacial contact between the material surface and the extracellular polymeric material. These electrons then enter the cell via the extracellular electron transport chain to participate in the Fe(III) reductase catalysis process, driving the reduction of Fe(III) to Fe(II), which then combines with phosphate to form minerals. Simultaneously, the holes generated by the piezoelectric effect utilize organic macromolecules such as humic acid, fulvic acid, and alcohols present in the wastewater as sacrificial agents, being promptly quenched through oxidation reactions. The degradation products can then be used as substrates for anaerobic microorganisms, thereby improving the degradation efficiency of organic matter in wastewater while avoiding oxidative damage to microbial cells. This mechanism requires no additional sacrificial agents, fully utilizes the wastewater's own components, and is low-cost and easy to operate. Scanning electron microscopy and zeta potential testing confirmed that pure bacterial cells not co-cultured with piezoelectric materials exhibited typical short rod-like shapes with relatively smooth surfaces. After co-culture, the piezoelectric material particles were stably attached to the bacterial surface through extracellular polymer bridging, forming a distinct "bacterial cell-material" composite structure. The zeta potential of the hybrid was significantly shifted compared to pure bacterial cells or pure piezoelectric materials, with a shift of not less than 10 mV. This indicates that a stable interfacial bond was formed between the piezoelectric material and the bacterial cells, which is conducive to the transfer of piezoelectric electrons to the active sites of electron transport proteins on the bacterial outer membrane via interfacial contact, thereby enhancing the extracellular electron transport process.
[0019] Based on the above mechanism, this invention can effectively activate the metabolic activity of functional microorganisms (such as *Geobacterium thioreductoides*) and optimize their extracellular electron transfer process, thereby reducing iron-containing substances in wastewater more quickly and directionally and crystallizing them with phosphate to form lapis lazuli. Compared with traditional biological methods, this method significantly shortens the reaction cycle and produces a product with higher purity and crystallinity. This invention directly treats phosphorus-containing wastewater, achieving efficient phosphate removal and mitigating the risk of eutrophication while converting it into high-value-added lapis lazuli crystals. It provides an energy-saving and sustainable new strategy for wastewater treatment and phosphorus resource recovery, filling the technological gap in the synergistic promotion of lapis lazuli formation through mechanical force and biomineralization.
[0020] Furthermore, in a preferred embodiment of the present invention, by optimizing process parameters such as the type and particle size of the piezoelectric material, the method of applying mechanical force, and reaction conditions, the biosynthesis efficiency of vivianite can be further improved. Experimental results show that the method of the present invention can significantly improve the yield and purity of vivianite. In the embodiments of the present invention, using barium titanate yields vivianite at a yield of 80.98 mg / L and a purity of 95%, while using tourmaline as the piezoelectric material yields an average yield of 60.12 mg / L and a purity of 93%. In the comparative example without the addition of piezoelectric material, the yield and purity of vivianite are significantly reduced under the same conditions, and the purity is also lower than that of the embodiments of the present invention, confirming that the piezoelectric effect has a significant promoting effect on the biosynthesis of vivianite. XRD and SEM characterization results confirm that the obtained product is vivianite with good crystallinity. The above results fully demonstrate that the synergistic effect of piezoelectric material and mechanical force can effectively promote the extracellular electron transfer and Fe(III) reduction of microorganisms, thereby significantly improving the biosynthesis efficiency and product quality of vivianite. Furthermore, this method can still effectively produce lapis lazuli in wastewater with low phosphorus concentrations, and the yield is better than the existing level, demonstrating good low-concentration phosphorus recovery capabilities and industrial application prospects.
[0021] Other beneficial effects of the embodiments of the present invention will be further described below. Attached Figure Description
[0022] Figure 1 This is a flowchart illustrating the overall process of the method for promoting microbial synthesis of vivianite based on piezoelectricity generated by mechanical stirring, as described in this invention.
[0023] Figure 2 This is a scanning electron microscope (SEM) image of *Geobacterium thioreductoides* in an embodiment of the present invention.
[0024] Figure 3 This is a superimposed elemental distribution diagram of the material obtained by scanning electron microscopy (SEM) and EDS in an embodiment of the present invention.
[0025] Figure 4 This is a scanning electron microscope (SEM) image of the bacteria-material hybrid in an embodiment of the present invention.
[0026] Figure 5 The image shows a Zeta diagram of pure bacteria and hybrids in an embodiment of the present invention.
[0027] Figure 6 This is the X-ray diffraction (XRD) pattern of the lapis lazuli product obtained in Example 1 of the present invention.
[0028] Figure 7 The image shows the blue iron ore product obtained in Example 2 of this invention, its scanning electron microscope (SEM) and EDS surface scan distribution of O, Fe and P elements. Detailed Implementation
[0029] The embodiments of the present invention will be described in detail below. It should be emphasized that the following description is merely exemplary and not intended to limit the scope and application of the present invention.
[0030] A method for promoting the biosynthesis of vivianite based on piezoelectricity generated by mechanical stirring mainly includes the following steps: activating bacteria to obtain an inoculum; culturing the bacteria with a piezoelectric material for a period of time to generate a bacterial-material hybrid with a specific morphology; inoculating the obtained bacterial-material hybrid into wastewater, applying external mechanical force, and reacting for a period of time; and separating the solid and liquid components of the reaction solution to obtain vivianite.
[0031] See Figure 1 This invention provides a method for promoting microbial synthesis of vivianite based on piezoelectricity generated by mechanical stirring, specifically including the following steps: Step S1: Providing inoculum. In some embodiments, step S1 specifically includes: inoculating bacteria into NBAF medium for enrichment culture, and culturing for 1-2 days to obtain inoculum. In some embodiments, in step S1, the inoculum is inoculated into the wastewater to be treated at a volume ratio of 1%-10% (inoculum / wastewater).
[0032] Step S2: Co-culture the bacteria with the piezoelectric material to generate a bacteria-material hybrid.
[0033] In some embodiments, in step S2, the volume ratio of the bacterial-material hybrid inoculation is 2% to 5%.
[0034] In some embodiments, the culture time in step S2 is 3 to 6 days.
[0035] In some embodiments, in step S2, the culture temperature is 22-26°C and the rotation speed is 120-150 rpm.
[0036] In some embodiments, the medium for generating the heterozygote in step S2 includes, but is not limited to, NBAF and LB medium.
[0037] In some embodiments, in step S2, the bacteria-material hybrid is a composite structure formed by piezoelectric material particles attaching to the surface of the bacteria through extracellular polymer bridging; the particle size of the piezoelectric material particles is 0.1 to 50 μm.
[0038] In some embodiments, in step S2, the criteria for determining the formation of the bacterial-material hybrid are: scanning electron microscopy shows that piezoelectric material particles are stably attached to the surface of the bacterial cell, and the zeta potential of the hybrid is at least 10 mV different from that of the pure bacterial cell or the pure material.
[0039] In some embodiments, in step S2, the piezoelectric material includes quartz, tourmaline, or barium titanate. For example, barium titanate generates piezoelectric electrons under mechanical stirring conditions, which are utilized by electroactive microorganisms (such as Thiobacillus thioreductans) in metabolic processes.
[0040] In some embodiments, in step S2, the bacteria-material hybrid is pure bacteria, pure material, or a product of co-culturing bacteria and material.
[0041] Step S3: Inoculate the bacteria-material hybrid into wastewater containing iron and phosphorus components, apply mechanical force to cause the piezoelectric material to generate piezoelectric electrons and holes, the piezoelectric electrons are transferred to the bacteria and participate in the extracellular electron transport chain, driving Fe(III) to be reduced to Fe(II) and combined with phosphate to form minerals, and the holes are quenched by organic matter in the wastewater.
[0042] In some embodiments, in step S3, the amount of piezoelectric material added is 0.1 to 1.0 g / L.
[0043] In some embodiments, in step S3, the piezoelectric electrons are transferred to the bacterial cells via direct and / or indirect pathways: the direct pathway involves electrons being transferred to the active sites of electron transport proteins on the outer membrane of the bacterial cells via interfacial contact between the piezoelectric material surface and the extracellular polymeric polymer of the bacterial cells, and then entering the cell via the extracellular electron transport chain to participate in the reduction of Fe(III); the indirect pathway involves electrons first reducing Fe in the system. 3+ / Fe 2+ The redox medium is then transferred to the microorganisms through a mediator cycle.
[0044] In some embodiments, in step S3, the mechanical force originates from an external stirring force, water flow, wind force, or tidal fluctuation.
[0045] In some embodiments, in step S3, the mechanical force is applied under anaerobic conditions: temperature 25–30°C, rotation speed 150–200 rpm, and reaction time 3–8 days. In some embodiments, high-purity nitrogen is introduced for 20 minutes before use of the anaerobic environment to remove oxygen.
[0046] In some embodiments, in step S3, the cavities are quenched by an oxidation reaction with organic matter in the wastewater, the organic matter including humic acid, fulvic acid and / or alcohols.
[0047] In some embodiments, in step S3, the wastewater comprises: sodium lactate 30-35 mmol / L, hydrated iron oxide 10-15 mmol / L, sodium dihydrogen phosphate 5-8 mmol / L, sodium bicarbonate 30-50 mmol / L, and ammonium chloride 2-5 mmol / L.
[0048] In some embodiments, the wastewater is aquaculture wastewater, and its components include: ammonia nitrogen (NH4Cl) 0.2-0.5 g / L, glucose 0.5-5 g / L, urea 0.3-4 g / L, sodium chloride 5-10 g / L, magnesium chloride 0.399-0.410 g / L and potassium dihydrogen phosphate 0.408-0.452 g / L.
[0049] Step S4: Solid-liquid separation to obtain lapis lazuli.
[0050] In some embodiments, in step S4, the solid-liquid separation is achieved by natural sedimentation, with a sedimentation time of 3 to 5 hours.
[0051] In some embodiments, after the formation of lapis lazuli, it is separated by natural sedimentation, washed with anhydrous ethanol, and dried at a constant temperature to obtain lapis lazuli.
[0052] In some embodiments, the microorganisms include, but are not limited to, *Geobacterium thioreductoides*.
[0053] In some preferred embodiments, the method for promoting the biosynthesis of vivianite from wastewater includes the following steps: The bacteria are activated to obtain an inoculum solution, specifically by inoculating *Geobacillus thioreductoides* into an enrichment medium and anaerobically culturing it to obtain the inoculum solution.
[0054] The obtained inoculum is inoculated into the wastewater, piezoelectric material is added to the wastewater, external mechanical force is applied, and the reaction is carried out for a period of time. Specifically, the inoculum is inoculated into the wastewater to be treated at a volume ratio of 1%-10% (inoculum / wastewater), and anaerobic culture is carried out for 48-144 hours at a temperature of 25-30℃ and a rotation speed of 150-200 rpm.
[0055] Morphology and identification of bacterial-material hybrids: The hybrid morphology consists of piezoelectric material particles (0.1~50 μm in diameter) attached to the bacterial cell surface through extracellular polymeric substances (EPS) bridging, forming a stable "material-bacterial cell" composite structure. The identification criteria are: visible adhesion and binding of material particles to the bacterial cell surface observed under scanning electron microscopy, and a Zeta potential shift of ≥10 mV compared to pure bacterial cells. After the formation of the hybrid, the culture can proceed to step S3, with a culture time typically of 3-6 days.
[0056] The ammonia nitrogen (NH4Cl) in the aquaculture wastewater is 0.2-0.5 g / L, glucose is 0.5-5 g / L, urea is 0.3-4 g / L, sodium chloride is 5-10 g / L, magnesium chloride is 0.399-0.410 g / L, and potassium dihydrogen phosphate is 0.408-0.452 g / L.
[0057] After the reaction, the solution was separated into solid and liquid phases to obtain vivianite. After the incubation period, the product was subjected to natural sedimentation, washing with anhydrous ethanol, and drying at a constant temperature to obtain vivianite.
[0058] In this invention, the shear force generated by mechanical stirring acts on the piezoelectric material, causing it to deform and generate piezoelectric electrons and holes. The specific pathway for electron transfer to microorganisms is as follows: the piezoelectric material deforms under mechanical force, generating piezoelectric electrons; these electrons are transferred to the active sites of electron transport proteins such as cytochrome c on the outer membrane of the bacteria through interfacial contact between the material surface and the extracellular polymeric substance (EPS); subsequently, they enter the bacteria via the extracellular electron transport chain, participate in the catalytic process of Fe(III) reductase, driving the reduction of Fe(III) to Fe(II), which then combines with phosphate to form minerals. This electron transfer pathway is based on the interfacial charge transfer mechanism between the piezoelectric material and electroactive microorganisms. Simultaneously, the holes (positive charges) generated by the piezoelectric effect are effectively managed through the following scheme: utilizing the abundant organic macromolecules (such as humic acid, fulvic acid, alcohols, etc.) in the wastewater as hole sacrificial agents, the holes react with the organic matter in an oxidation reaction, thereby being quenched in time. This reaction does not consume exogenous chemical reagents, and simultaneously degrades large organic molecules into smaller molecules, which can serve as substrates for anaerobic microorganisms to utilize, thus ensuring their activity. Furthermore, the cavities may also be consumed through oxidation reactions with organic substrates in the system (such as sodium lactate), further reducing the risk of oxidative damage to microbial cells. This cavity management scheme requires no additional sacrificial agents, fully utilizes the wastewater's own components, and is simple to operate and cost-effective.
[0059] Building upon this foundation, this invention creatively constructs a "mechanical force-piezoelectric effect-biosynthesis" coupling mechanism. This mechanism converts widely available low-grade mechanical energy in the environment (such as water flow, stirring force, wind force, or tidal fluctuations) into electrical energy that microorganisms can directly utilize, directly influencing their biosynthetic processes. This coupling mechanism significantly promotes the formation rate and yield of vivianite without requiring additional chemical agents or consuming large amounts of electrical energy, representing a green and efficient process intensification technology.
[0060] Furthermore, under the synergistic effect of piezoelectric materials and mechanical force, the micro-electric field and active substances generated within the system can effectively stimulate the metabolic activity of functional microorganisms (such as *Geotrichum thioreductobacillus*), optimizing their extracellular electron transfer process. This allows for a faster and more targeted reduction of iron-containing substances in wastewater, crystallizing them with phosphate to form lapis lazuli. Compared to traditional biological methods, this method significantly shortens the reaction cycle and yields higher purity and crystallinity of the target product. Simultaneously, the electrons and holes generated by the piezoelectric effect can also influence microbial metabolic processes and the formation of extracellular polymers, promoting the biomineralization synthesis of lapis lazuli by various microbial species. This significantly improves the degradation and utilization efficiency of iron-phosphorus components in wastewater, enabling its use in the biomineralization recovery of iron-phosphorus components from aquaculture wastewater, thereby significantly increasing the yield and purity of lapis lazuli. By rationally selecting the type of mechanical force and optimizing the piezoelectric materials, the biosynthesis efficiency of lapis lazuli can be further improved. Mechanical force itself can also significantly enhance mass transfer efficiency, change cell membrane permeability, and even affect enzyme conformation through physical mechanisms such as cavitation effect, shear force, and micromixing, thereby further activating or accelerating the extracellular reduction and mineralization process of microorganisms without relying on a large amount of organic substrate.
[0061] This invention directly treats phosphorus-containing wastewater (including aquaculture wastewater, etc.), achieving efficient phosphate removal and mitigating the risk of eutrophication while converting it into high-value-added lapis lazuli crystals. The method is simple to operate, environmentally friendly, and significantly reduces the production cost and energy consumption of lapis lazuli. In some embodiments, even in wastewater with low phosphorus concentrations, lapis lazuli can still be effectively produced with yields superior to existing levels.
[0062] In summary, this invention not only broadens the pathways for utilizing mechanical energy but also provides a new, energy-saving, and sustainable strategy for wastewater treatment and phosphorus resource recovery. It fills the technological gap in the synergistic promotion of vivianite formation through mechanical force and biomineralization, and has broad application prospects in phosphorus resource recovery, wastewater treatment, and high-value mineral production. This method is simple, effective, low-cost, widely applicable, and economically practical, with outstanding technical value for wastewater resource recovery.
[0063] The following detailed description of the method for promoting the biosynthesis of vivianite using mechanical force and its effects, with reference to specific embodiments and comparative examples, is provided below.
[0064] Example 1
[0065] A method for promoting the biosynthesis of vivianite based on piezoelectricity generated by mechanical stirring includes the following steps: (1) Thio-reducing bacteria were inoculated into 100 mL of enrichment medium (NBAF medium) and anaerobic cultured for 1 day at 30 °C and 150 rpm to obtain the inoculum.
[0066] The sulfur-reducing Geobacterium in the inoculum obtained in step (1) was observed by scanning electron microscopy, and the results are as follows: Figure 2 As shown. By Figure 2 As can be seen, pure bacterial cells are typically short rod-shaped with a relatively smooth surface and good dispersibility. For example... Figure 3 As shown, the tourmaline material is in the form of irregular granules, with particle size ranging from micrometers to nanometers.
[0067] (2) Prepare the wastewater used in this embodiment: sodium lactate 30 mmol / L, hydrated iron oxide 10 mmol / L, sodium dihydrogen phosphate 5 mmol / L, sodium bicarbonate 30 mmol / L, ammonium chloride 5 mmol / L. pH 7.0, then purge with nitrogen for 20 min to remove oxygen, and then sterilize in a high temperature and high pressure autoclave at 121℃ for 20 min for later use.
[0068] (3) The inoculum was then inoculated into NBAF medium at 1% (inoculum / wastewater) and 0.1 g / L of tourmaline was added. The mixture was anaerobic cultured for 4 days at 30°C and 150 rpm. The bacteria-material hybrid was obtained by filtration and separation.
[0069] The bacterial-material hybrid obtained in step (3) was observed by scanning electron microscopy, and the results are as follows: Figure 4 As shown. By Figure 4 It is evident that tourmaline particles are stably attached to the bacterial cell surface through extracellular polymer bridging, forming a distinct bacteria-material hybrid structure. Zeta potential test results indicate (e.g.) Figure 5 The Zeta potential of the hybrid cells showed a significant shift compared to the pure cells, with a shift exceeding 10 mV, indicating that a stable bond had formed between the tourmaline particles and the cells.
[0070] (4) The above-mentioned hybrid was added to the wastewater obtained in (2) and anaerobic cultured for 4 days at a temperature of 30℃ and a rotation speed of 150 rpm. The crystal formation was observed every 24 hours.
[0071] (5) After the culture is completed, the product is separated by sedimentation, washed with ethanol, and placed in an oven to dry at a constant temperature for 30 minutes until constant weight is obtained, thus obtaining the blue iron ore product.
[0072] The obtained vivianite product was characterized and analyzed. X-ray diffraction results showed (e.g.) Figure 6The product exhibited characteristic diffraction peaks of vivianite at 2θ of approximately 11.16°, 23.4°, and 32.1°, consistent with the standard card PDF#30-0662, and no obvious impurity peaks were observed. Scanning electron microscopy revealed that the product displayed a typical vivianite crystal morphology with good crystallinity. These results demonstrate that the method of this invention can yield vivianite products with high purity and good crystallinity. Characterization analysis of the results of three parallel experiments showed that the average yield of vivianite obtained in Example 1 was 60.12 mg / L, with a purity of 93%.
[0073] Example 2
[0074] A method for promoting the biosynthesis of vivianite based on piezoelectricity generated by mechanical stirring includes the following steps: (1) Thio-reducing bacteria were inoculated into 100 mL of enrichment medium (NBAF medium) and anaerobic cultured for 1 day at 30°C and 150 rpm to obtain the inoculum.
[0075] (2) Prepare the wastewater used in this embodiment: sodium lactate 30 mmol / L, hydrated iron oxide 10 mmol / L, sodium dihydrogen phosphate 5 mmol / L, sodium bicarbonate 30 mmol / L, ammonium chloride 5 mmol / L. pH 7.0, then purge with nitrogen for 20 min to remove oxygen, and then sterilize in a high temperature and high pressure autoclave at 121℃ for 20 min for later use.
[0076] (3) The inoculum was then inoculated into NBAF medium at a concentration of 1% (inoculum / wastewater), and 0.1 g / L of barium titanate was added. The mixture was then anaerobic cultured for 4 days at 30 ℃ and 150 rpm. The bacteria-material hybrid was obtained by filtration. Under mechanical stirring, barium titanate generates piezoelectric electrons, which are utilized by sulfur-reducing bacteria in the metabolic process, effectively exerting the piezoelectric effect to promote biosynthesis.
[0077] The obtained bacterial-material hybrids were observed by scanning electron microscopy and analyzed by zeta potential. The results showed that barium titanate particles were stably attached to the surface of *Geobacterium thioretinib*, and the zeta potential of the hybrids shifted by more than 10 mV compared to the pure bacterial cells, indicating a stable interfacial bond between barium titanate and the bacterial cells. Under mechanical stirring, barium titanate generated piezoelectric electrons, which could be transferred to the bacterial cells and participate in the extracellular electron transport chain, thereby promoting Fe(III) reduction and lapis lazuli mineralization.
[0078] (4) The above-mentioned hybrid was added to the wastewater obtained in (2) and anaerobic cultured for 4 days at a temperature of 30℃ and a rotation speed of 150 rpm. The crystal formation was observed every 24 hours.
[0079] (5) After cultivation, the product is separated by sedimentation, washed with ethanol, and dried in an oven at a constant temperature for 30 minutes until constant weight is obtained, thus obtaining the lapis lazuli product (e.g. Figure 7 As shown in the image).
[0080] Characterization analysis of the results of three parallel experiments revealed an average yield of 80.98 mg / L and a purity of 95% for vivianite.
[0081] Comparative Example
[0082] To verify the promoting effect of piezoelectricity on the synthesis of vivianite, a comparative example was set up: except that no piezoelectric material was added, all other conditions were the same as in Example 1.
[0083] The specific steps are as follows: (1) Inoculate the sulfur-reducing bacteria into a container of 100 mL enrichment medium (NBAF medium) and anaerobic culture for 1 day at a temperature of 30℃ and a rotation speed of 150 rpm to obtain the inoculum.
[0084] (2) Preparation of wastewater: sodium lactate 30 mmol / L, hydrated iron oxide 10 mmol / L, sodium dihydrogen phosphate 5 mmol / L, sodium bicarbonate 30 mmol / L, ammonium chloride 5 mmol / L, pH 7.0, nitrogen gas is introduced for 20 min to remove oxygen, and then sterilized at 121℃ for 20 min for later use.
[0085] (3) Inoculate the inoculum at 1% (inoculum / wastewater) into NBAF medium and anaerobic culture for 4 days at 30℃ and 150rpm to obtain pure bacterial cells without piezoelectric materials.
[0086] (4) Add the pure bacterial cells to the wastewater obtained in (2) and anaerobic culture for 4 days at a temperature of 30℃ and a rotation speed of 150 rpm. Observe the crystal formation every 24 hours.
[0087] (5) After the culture is completed, the product is separated by sedimentation, washed with ethanol, and placed in an oven to dry at a constant temperature for 30 min until constant weight is obtained to obtain the blue iron ore product.
[0088] Characterization analysis of the results of three parallel experiments showed that without the addition of piezoelectric materials, the average yield of vivianite was only 5.06 mg / L, and the purity was only 48%. Compared with Example 1, the yield of vivianite in the comparative example decreased by 92%, and the purity decreased by 45 percentage points; compared with Example 2, the yield of vivianite in the comparative example decreased by 94%, and the purity decreased by 47 percentage points (as shown in Table 1). These results confirm that the synergistic effect of piezoelectric materials and mechanical force significantly promotes the biosynthesis of vivianite. The piezoelectric electrons generated by the piezoelectric effect can effectively participate in the extracellular electron transfer process of microorganisms, driving the reduction of Fe(III) to Fe(II) and its combination with phosphate to form minerals, thereby increasing the yield and purity of vivianite.
[0089] Table 1 Comparison of blue iron ore yield and purity in Example 1, Example 2 and Comparative Examples
[0090] Scanning electron microscopy revealed that the pure bacterial cells, without co-culture with the piezoelectric material, exhibited typical short rod-like shapes and relatively smooth surfaces. After co-culturing with the piezoelectric material, the resulting bacterial-material hybrids showed that the piezoelectric material particles were stably attached to the bacterial surface through extracellular polymer bridging, forming a distinct "bacterial cell-material" composite structure. Zeta potential testing showed that the zeta potential of the hybrids was significantly shifted compared to pure bacterial cells or pure piezoelectric material, with a shift of no less than 10 mV, indicating a stable interfacial bond between the piezoelectric material and the bacterial cells. This interfacial structure facilitates the transfer of piezoelectric electrons to the active sites of electron transport proteins on the bacterial outer membrane via interfacial contact between the material surface and the extracellular polymeric layer, thereby enhancing the extracellular electron transport process.
[0091] Experimental results show that the method of this invention can significantly improve the yield and purity of vivianite. In Example 2, using *Geobacterium thioreductoides* as the functional microorganism and barium titanate as the piezoelectric material, the average yield of vivianite reached 80.98 mg / L and the purity reached 95% after 4 days of reaction under mechanical stirring. In Example 1, when tourmaline was used as the piezoelectric material, the average yield of vivianite was 60.12 mg / L and the purity was 93%. In the comparative example without the addition of piezoelectric material, the yield of vivianite was significantly reduced under the same conditions, and the purity was also lower than that of Examples 1 and 2. The above results demonstrate that the synergistic effect of piezoelectric material and mechanical force can effectively promote the extracellular electron transfer and Fe(III) reduction of microorganisms, thereby significantly improving the biosynthetic efficiency and product quality of vivianite.
[0092] This invention utilizes mechanical force to promote the biosynthesis of lapis lazuli, demonstrating the effectiveness of applying mechanical force in wastewater resource recovery. The application of external mechanical force significantly promotes lapis lazuli formation and reduces impurities in the product, proving the great potential of piezoelectric effects in promoting microbial growth in wastewater treatment. This invention innovatively converts abundant environmental mechanical forces (such as water flow and agitation) into usable electrical energy through piezoelectric materials, directly acting on the microbial biosynthetic process—a green and efficient process intensification technology. Furthermore, under the synergistic effect of piezoelectric materials and mechanical force, the micro-electric field and active substances generated within the system effectively stimulate the metabolic activity of functional microorganisms (such as *Geotrichum thioreductobacillus*), optimizing their extracellular electron transfer process. This allows for a faster and more targeted reduction of iron-containing substances in wastewater, crystallizing them with phosphate to form lapis lazuli. Compared to traditional biological methods, this method shortens the reaction cycle and achieves higher purity and crystallinity of the target product. This invention directly targets phosphorus-containing wastewater for treatment. While achieving efficient removal of phosphate and mitigating the risk of eutrophication, it transforms phosphate into high-value lapis lazuli crystals. The entire process is simple to operate and environmentally friendly, greatly reducing the production cost and energy consumption of lapis lazuli. It has broad application prospects in the fields of phosphorus resource recovery, wastewater treatment, and high-value mineral production.
[0093] In summary, this invention, through a coupling mechanism of "mechanical force-piezoelectric effect-biosynthesis," converts mechanical energy into electrical energy usable by microorganisms, significantly enhancing the extracellular electron transfer process of electroactive microorganisms such as *Geotrichum thioreductoides*, and promoting Fe(III) reduction and phosphate mineralization. The results of the examples show that the yield of lapis lazuli was 60.12 mg / L and the purity was 93% when tourmaline was added; the yield was 80.98 mg / L and the purity was 95% when barium titanate was added; and in the comparative example without piezoelectric material, both the yield and purity of lapis lazuli were significantly reduced. SEM and Zeta potential results demonstrate that the piezoelectric material is stably attached to the bacterial surface through extracellular polymer bridging, forming a bacteria-material hybrid; XRD and SEM results confirm that the obtained product is lapis lazuli with good crystallinity. The above data fully demonstrate that the method of this invention can effectively improve the biosynthetic efficiency, product purity, and crystallinity of lapis lazuli, exhibiting significant technical effects and promising prospects for industrial application.
[0094] The above description, in conjunction with specific / preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various substitutions or modifications can be made to these described embodiments without departing from the inventive concept, and all such substitutions or modifications should be considered within the scope of protection of the present invention.
Claims
1. A method for promoting microbial synthesis of vivianite based on piezoelectricity generated by mechanical stirring, characterized in that, Includes the following steps: S1. Provide inoculum solution; S2. Co-culture bacteria with piezoelectric materials to generate bacteria-material hybrids; S3. The bacteria-material hybrid is inoculated into wastewater containing iron and phosphorus components. Mechanical force is applied to cause the piezoelectric material to generate piezoelectric electrons and holes. The piezoelectric electrons are transferred to the bacteria and participate in the extracellular electron transport chain, driving Fe(III) to be reduced to Fe(II) and combined with phosphate to form minerals. The holes are quenched by organic matter in the wastewater. S4. Solid-liquid separation yields lapis lazuli.
2. The method according to claim 1, characterized in that, In step S2, the bacteria-material hybrid is a composite structure formed by piezoelectric material particles attaching to the surface of the bacterial cell through extracellular polymer bridging; the particle size of the piezoelectric material particles is 0.1 to 50 μm.
3. The method according to claim 2, characterized in that, In step S2, the criteria for determining the formation of the bacterial-material hybrid are: scanning electron microscopy shows that piezoelectric material particles are stably attached to the surface of the bacterial cell, and the zeta potential of the hybrid is at least 10mV different from that of the pure bacterial cell or the pure material.
4. The method according to claim 1, characterized in that, In step S2, the piezoelectric material includes quartz, tourmaline, or barium titanate.
5. The method according to claim 1, characterized in that, In step S3, the piezoelectric electrons are transferred to the bacterial cells via direct and / or indirect pathways: the direct pathway involves electrons contacting the interface between the piezoelectric material surface and the extracellular polymeric polymer of the bacterial cells, transferring to the active sites of electron transport proteins on the outer membrane of the bacterial cells, and then entering the cell via the extracellular electron transport chain to participate in the reduction of Fe(III); the indirect pathway involves electrons first reducing Fe³⁺ in the system. + / Fe² + The redox medium is then transferred to the microorganisms through a mediator cycle.
6. The method according to claim 1, characterized in that, In step S3, the cavities are quenched by an oxidation reaction with organic matter in the wastewater, including humic acid, fulvic acid, and / or alcohols.
7. The method according to claim 1, characterized in that, In step S3, the mechanical force originates from external stirring force, water flow, wind force, or tidal fluctuations.
8. The method according to claim 1, characterized in that, In step S3, the wastewater comprises: sodium lactate 30-35 mmol / L, hydrated iron oxide 10-15 mmol / L, sodium dihydrogen phosphate 5-8 mmol / L, sodium bicarbonate 30-50 mmol / L, and ammonium chloride 2-5 mmol / L.
9. The method according to claim 1, characterized in that, In step S3, the mechanical force is applied under the following conditions: temperature 25-30°C, rotation speed 150-200 rpm, and reaction time 3-8 days.
10. The method according to claim 1, characterized in that, In step S4, the solid-liquid separation is achieved by natural sedimentation, with a sedimentation time of 3 to 5 hours.