A piezoelectric method for sludge deep dewatering

Abstract

The application discloses a piezoelectric method for sludge deep dewatering, which is mainly applied to the field of sludge dewatering such as water treatment. The method adopts a nano-wire (needle, rod) structure of piezoelectric ceramic barium titanate, and the micro-nano high aspect ratio morphology is particularly suitable for sludge dewatering. The barium titanate nano-wire (needle) can directly respond to the filter pressing pressure and centrifugal force on the basis of the existing sludge filter pressing and centrifugal dewatering process through the local piezoelectric field amplification effect of the tip, generate a high-strength local electric field on the material surface and the tip, effectively cause the difficult-to-dewater bacterial cell liquid to seep out without the help of any chemical dewatering agent, and achieve the purpose of sludge deep dewatering. The method not only has a comparable sludge dewatering efficiency, but also avoids the use cost and environmental pollution hazards caused by the use of chemical agents in the above two traditional sludge dewatering processes. The method is simple, environment-friendly and easy to implement, and provides an efficient solution for sludge deep dewatering treatment.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sludge dewatering and related wastewater treatment, and specifically relates to a piezoelectric method for sludge deep dewatering. BACKGROUND

[0002] Sludge is a byproduct of natural or biological wastewater treatment processes, mainly composed of microbial cells, organic matter, inorganic particles and water. The high water content of sludge (usually up to 90-99%) not only increases the difficulty of treatment and disposal, but also significantly increases the transportation and treatment cost. Therefore, effective sludge dewatering is a crucial step in the wastewater treatment process, which not only reduces the volume of sludge and reduces the treatment cost, but also helps subsequent sludge disposal or resource utilization. Currently, common sludge dewatering methods include mechanical dewatering (such as filter pressing, centrifugation), chemical dewatering (using flocculants or conditioners) and natural dewatering (such as sunning). Mechanical dewatering has a direct effect, but consumes a lot of energy; chemical dewatering can improve dewatering efficiency, but increases the use of chemical agents, which may cause environmental pollution; natural dewatering is low in cost, but also extremely low in efficiency, and is limited by weather conditions. These methods have their own advantages and disadvantages, but generally have problems such as low dewatering efficiency, high energy consumption or environmental pollution.

[0003] Barium titanate is an environmentally friendly piezoelectric material. Although there are very few reports on sludge dewatering, for example, invention patent (application number: 201911289167.3) and paper (Water Research, 209 (2022) 117922) attempt to use barium titanate for sludge dewatering, but both have the problem of needing to assist with chemical agents or the barium titanate material itself needing to be loaded with other catalysts for dewatering. SUMMARY

[0004] The purpose of the application is to provide a green and efficient piezoelectric method for sludge deep dewatering.

[0005] Technical solution: A piezoelectric method for sludge deep dewatering, the piezoelectric material used in the piezoelectric method is a tetragonal phase piezoelectric barium titanate with a linear, needle-like or rod-like overall shape, or a tetragonal phase piezoelectric barium titanate with local elongated micro-nano morphology.

[0006] As a further improvement of the application, the piezoelectric material is prepared by the following method:

[0007] H2Ti3O7 nanowires react with Ba(OH)2·8H2O aqueous solution to obtain BaTiO3 nanowires, i.e. piezoelectric material.

[0008] As a further improvement of the application, H2Ti3O7 nanowires are prepared by the following method:

[0009] The Na2Ti3O7 nanowires are washed to neutral, and then soaked in an aqueous hydrochloric acid solution for a period of time to generate H2Ti3O7 nanowires.

[0010] As a further improvement of the present application, the H2Ti3O7 nanowires are prepared by the following method:

[0011] The TiO2 nanometer powder is mixed with an aqueous NaOH solution, stirred for a period of time to obtain a mixed solution; the mixed solution is sealed and stored for a period of time to obtain Na2Ti3O7 nanowires.

[0012] Preferably, the particle size of the piezoelectric barium titanate is 100 nm to 10 microns.

[0013] As a further improvement of the present application, the piezoelectric method for deep dewatering of sludge is based on pressure filtration and centrifugal sludge dewatering.

[0014] As a further improvement of the present application, in the pressure filtration, the pressure is 1 to 20 MPa, and the action time is 1 to 5 hours.

[0015] As a further improvement of the present application, in the centrifugal sludge dewatering, the centrifugal speed is 5000 to 50000 rpm, and the action time is 10 to 60 minutes.

[0016] As a further improvement of the present application, the addition amount of the piezoelectric material is 0.1 to 10 kg per ton of sludge, and is uniformly mixed.

[0017] As a further improvement of the present application, the sludge in the deep dewatering of sludge includes one or more of treated municipal sewage sludge, treated industrial sewage sludge, and bottom mud precipitated in natural or artificial water pools.

[0018] The piezoelectric sludge deep dewatering method proposed in the present application uses nanowire (needle, rod) morphology of nanometer barium titanate, which can avoid the above technical deficiencies in sludge dewatering and has significant technical advantages. In addition, the improvement of sludge dewatering effect brought by the morphology of barium titanate has never been reported and concerned. The sharp structure of barium titanate nanowire (needle, rod) can respond to pressure or centrifugal force during sludge treatment, generating a local high-intensity piezoelectric field of up to 10 7 V / m and above in situ, which can effectively perform electroporation on the cell membranes of microorganisms in the sludge. Electroporation is a unique physical process that can destroy the integrity of the cell membrane and promote the release of water and dissolved substances in the cell, thereby achieving deep dewatering of sludge. Compared with traditional sludge dewatering methods or existing piezoelectric sludge dewatering schemes, this method does not require an external power source or the use of chemical agents, greatly reducing energy consumption and environmental impact.

[0019] In addition, the use of barium titanate nanowires (needles, rods) also has other advantages, such as easy operation, high cost-effectiveness, and environmental friendliness. This new dewatering technology is not only suitable for municipal sewage treatment, but also for industrial wastewater treatment, especially in the application of sludge deep dewatering, showing great application potential. In the future, with the increasing demand for environmental protection and resource utilization, this efficient and green sludge dewatering technology is expected to be widely used worldwide, with important practical application value and broad market prospects.

[0020] Advantages: Compared with the prior art, the present application has the following significant advantages:

[0021] (1) Improve dewatering efficiency: By utilizing the unique elongated micro-nano morphology and local high-intensity electric field of barium titanate nanowires (needles, rods), the present application can more effectively destroy the microbial cell membranes in the sludge, thereby promoting the release of intracellular water and dissolved substances. This mechanism significantly improves the dewatering efficiency of the sludge, especially when dealing with difficult-to-degrade or high-concentration organic sludge.

[0022] (2) Reduce energy consumption and cost: Since the present application does not require external power supply or chemical reagents, the energy consumption during operation is significantly reduced. At the same time, the use of chemical reagents is avoided, reducing material costs and processing costs, making the entire sludge dewatering process more economical and efficient.

[0023] (3) Environmentally friendly: The present application avoids the use of chemical reagents, thereby reducing the environmental secondary pollution problems that may be caused by the use of chemical reagents in existing filter pressing or filter pressing combined with piezoelectric sludge dewatering processes. Barium titanate nanowires (needles, rods) as an environmentally friendly material, its application not only improves the dewatering efficiency, but also meets the current environmental protection and sustainable development trend.

[0024] (4) Easy to operate: The operation process of the present application is simple, easy to combine with existing sludge treatment processes, without the need for special operation training or complex equipment modification, facilitating rapid implementation in existing sewage treatment systems. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a local electric field intensity simulation diagram of a 1 μm long rod-shaped barium titanate under a 10 Mpa filter pressing environment. DETAILED DESCRIPTION

[0026] The present application will be further explained in conjunction with the following examples. The following examples are only used to illustrate the present application, but not to limit the scope of the present application.

[0027] The embodiment of the present application provides a piezoelectric method for sludge deep dewatering, and the piezoelectric material used is tetragonal phase piezoelectric barium titanate which is linear, needle-shaped, rod-shaped or locally has the elongated micro-nano morphology characteristics.

[0028] As Figure 1 represented by the rod-shaped barium titanate with a length of 1 μm, the local electric field intensity simulation under the 10 Mpa pressure filtration environment can be seen from the figure, and the local electric field at the tip can be as high as 10 7 V / m, which can act on the microorganisms in the sludge to perform the piezoelectric deep sludge dewatering.

[0029] In the embodiment of the present application, the particle size of the piezoelectric barium titanate is 100 nm-10 μm. The piezoelectric method for sludge deep dewatering is based on the pressure filtration and centrifugal sludge dewatering process. In the pressure filtration process, the pressure range is 1-20 MPa, and the action time is 1-5 h; in the centrifugal process, the centrifugal speed is 5000-50000 rpm, and the action time is 10-60 min. The barium titanate is added in an amount of 0.1-10 kg per ton of sludge and is uniformly mixed. The sludge in the piezoelectric sludge deep dewatering includes the sludge treated by municipal sewage sludge, the sludge treated by industrial sewage sludge, and the bottom mud precipitated in a natural pond or an artificial pond.

[0030] Embodiment 1

[0031] The tetragonal phase rod-shaped piezoelectric barium titanate with a particle size of about 10 μm is added in an amount of 10 kg per ton of municipal sewage sludge with a water content of about 99%, and is uniformly mixed. The sludge system is dewatered by using the physical pressure filtration process, the pressure filtration process pressure is 20 Mpa, and the action time is 5 h. The water content of the sludge after pressure filtration is reduced to 50% or less, and the weight is reduced by about 95%.

[0032] The tetragonal phase rod-shaped piezoelectric barium titanate in the embodiment is prepared by the following method:

[0033] Preparation of H2TiO3 (precursor):

[0034] a) 3 g of TiO2 nano powder is mixed with 60 mL of 20 mol / L NaOH aqueous solution, and stirred for 24 h.

[0035] b) sealed in a 90 mL Teflon autoclave, and stored in a 180℃ oven for 3 days. Na2Ti3O7 nanowires are obtained

[0036] c) the Na2Ti3O7 nanowires are washed with deionized water and ethanol until ph is neutral, and then are soaked in 0.1 mol / L hydrochloric acid aqueous solution for 12 h to generate hydrogen titanate (H2Ti3O7). The obtained H2Ti3O7 nanowires are dried in a vacuum oven at 100℃.

[0037] BaTiO3nanowires (wire-like or rod-like, needle-like):

[0038] BaTiO3nanowires were synthesized by reacting 0.15 g H2Ti3O7with 0.05 mol / L Ba(OH)2·8H2O aqueous solution at 210 °C for 85 min. The final product was washed with 0.2 mol / L HCl solution, deionized water and alcohol, and then dried.

[0039] Comparative Example 1

[0040] The tetragonal phase spherical barium titanate piezoelectric with a particle size of about 10 μm was added to the municipal sewage sludge with a water content of about 99% by weight at 10 kg per ton, and mixed uniformly. The sludge system was dewatered using a physical pressure filtration process, and the pressure filtration process pressure was 20 MPa and the action time was 5 h. The water content of the sludge after pressure filtration was reduced to about 70%, and the weight was reduced by about 80%.

[0041] The tetragonal phase spherical barium titanate piezoelectric in the present comparative example was a commercial nanometer round particle, which was purchased from Aladdin Industrial Corporation, and then baked to 800 °C.

[0042] Example 2

[0043] The tetragonal phase wire-like barium titanate piezoelectric with a particle size of about 1 μm was added to the industrial sewage sludge with a water content of about 95% by weight at 1 kg per ton, and mixed uniformly. The sludge system was dewatered using a physical pressure filtration process, and the pressure filtration process pressure was 10 MPa and the action time was 3 h. The water content of the sludge after pressure filtration was reduced to 50% or less, and the weight was reduced by about 95%.

[0044] The preparation method of the tetragonal phase wire-like barium titanate piezoelectric used in the present example was the same as that of Example 1.

[0045] Comparative Example 2

[0046] The tetragonal phase block-like barium titanate piezoelectric with a particle size of about 1 μm was added to the industrial sewage sludge with a water content of about 95% by weight at 1 kg per ton, and then the sludge conditioner polyacrylamide and the iron chloride flocculant were added to the sludge at 1% of the sludge mass, and mixed uniformly. The sludge system was dewatered using a physical pressure filtration process, and the pressure filtration process pressure was 10 MPa and the action time was 3 h. The water content of the sludge after pressure filtration was reduced to about 60%, and the weight was reduced by about 90%.

[0047] The preparation method of the tetragonal phase block-like barium titanate piezoelectric used in the present comparative example was as follows:

[0048] BaTiO3nanowires (wire-like or rod-like, needle-like):

[0049] BaTiO3nanoparticles were synthesized by reacting 0.5152 g of H2Ti3O7with 0.2 mol / L aqueous Ba(OH)2*8H2O solution at 240°C for 12 h. The final product was washed with 0.2 mol / L HCl solution, deionized water and alcohol, and then dried.

[0050] Example 3

[0051] The tetragonal phase needle-like barium titanate piezoelectric with a particle size of about 100 nm was added to 0.1 kg of the bottom mud mixed with the natural pool and artificial pool sediment with a water content of about 90% per ton, and mixed uniformly. The sludge system was dewatered using a physical pressure filtration process, and the pressure filtration process pressure was 1 MPa, and the action time was 1 h. The water content of the sludge after pressure filtration was reduced to 50% or less, and the weight was reduced by about 95%.

[0052] The preparation method of the tetragonal phase needle-like barium titanate piezoelectric used in this example was the same as that of Example 1.

[0053] Comparative Example 3

[0054] The tetragonal phase irregular barium titanate piezoelectric with a particle size of about 100 nm was added to 0.1 kg of the bottom mud mixed with the natural pool and artificial pool sediment with a water content of about 90% per ton, and 3% of the sludge conditioner polyacrylamide, ferric chloride flocculant and calcium oxide were added to the sludge according to the mass of the sludge, and mixed uniformly. The sludge system was dewatered using a physical pressure filtration process, and the pressure filtration process pressure was 1 MPa, and the action time was 1 h. The water content of the sludge after pressure filtration was reduced to about 55%, and the weight was reduced by about 90%.

[0055] The preparation method of the tetragonal phase irregular barium titanate piezoelectric used in this example was as follows:

[0056] Synthesis of BaTiO3nanosheets:

[0057] First, H 1.07 Ti 1.73 O4·nH2O layered titanate was synthesized:

[0058] 1. The same stoichiometric amounts of K2CO3and TiO2(anatase) and 10% excess Li2CO3were mixed and ground together to obtain a mixture.

[0059] 2. The starting mixture was mixed with a K2MoO4fluxing agent in a molar ratio (K 0.8 Ti 1.73 Li 0.27 O4 / K2MoO4) = 3 / 7, then heated to 1100°C at a heating rate of 150°C / h and kept at this temperature for 5 hours. After natural cooling in the furnace, the sample was washed with boiling water to remove the K2MoO4fluxing agent and dried at room temperature to obtain K 0.8Ti 1.73 Li 0.27 O4.

[0060] 3、H 1.07 Ti 1.73 O4.nH2O layered titanate is prepared by treating K 0.8 Ti 1.73 Li 0.27 O4(10 g) with 1 mol / L HNO3 solution (1 L) for 1 day to exchange K+and Li+in the layered structure with H+. The acid treatment is repeated twice to complete the ion exchange reaction. The ion-exchanged sample is washed with distilled water and dried at room temperature.

[0061] Then 0.147 g H 1.07 Ti 1.73 O4.nH2O and 0.4 mol / L Ba(OH)2.8H2O aqueous solution are hydrothermally reacted at 210°C for 24 h to form.

[0062] Example 4

[0063] The tetragonal phase rod-like barium titanate piezoelectric with a particle size of about 10 μm is added to the municipal sewage sludge with a water content of about 99% per ton at 10 kg and mixed uniformly. The sludge system is dewatered using a physical centrifugal process, the centrifugal rotation speed is 50000 rpm, and the action time is 60 min. The water content of the sludge after centrifugation is reduced to about 50%, and the weight is reduced by about 95%.

[0064] The preparation method of the tetragonal phase linear barium titanate piezoelectric used in this example is the same as that of Example 1.

[0065] Comparative Example 4

[0066] The tetragonal phase spherical barium titanate piezoelectric with a particle size of about 10 μm is added to the municipal sewage sludge with a water content of about 99% per ton at 10 kg, and mixed uniformly. The sludge system is dewatered using a physical centrifugal process, the centrifugal rotation speed is 50000 rpm, and the action time is 60 min. The water content of the sludge after centrifugation is reduced to about 70%, and the weight is reduced by about 80%.

[0067] The tetragonal phase spherical barium titanate piezoelectric in this comparative example is a commercial nanometer round particle, purchased from Aladdin Industrial Corporation, and then baked to 800°C.

[0068] Example 5

[0069] The tetragonal phase barium titanate with a particle size of about 1 μm was added to 1 kg of industrial wastewater sludge with a water content of about 95% per ton, and mixed uniformly. The sludge system was dewatered using a physical centrifugal process, with a centrifugal speed of 10,000 rpm and an action time of 30 min. The water content of the sludge after centrifugation was reduced to about 50%, and the weight was reduced by about 95%.

[0070] The tetragonal phase barium titanate with a particle size of about 1 μm was added to 1 kg of industrial wastewater sludge with a water content of about 95% per ton, and mixed uniformly. The sludge system was dewatered using a physical centrifugal process, with a centrifugal speed of 10,000 rpm and an action time of 30 min. The water content of the sludge after centrifugation was reduced to about 50%, and the weight was reduced by about 95%.

[0071] Comparative Example 5

[0072] The tetragonal phase barium titanate with a particle size of about 1 μm was added to 1 kg of industrial wastewater sludge with a water content of about 95% per ton, and mixed uniformly. The sludge system was dewatered using a physical centrifugal process, with a centrifugal speed of 10,000 rpm and an action time of 30 min. The water content of the sludge after centrifugation was reduced to about 50%, and the weight was reduced by about 95%.

[0073] The tetragonal phase barium titanate with a particle size of about 1 μm was added to 1 kg of industrial wastewater sludge with a water content of about 95% per ton, and mixed uniformly. The sludge system was dewatered using a physical centrifugal process, with a centrifugal speed of 10,000 rpm and an action time of 30 min. The water content of the sludge after centrifugation was reduced to about 50%, and the weight was reduced by about 95%.

[0074] Example 6

[0075] The tetragonal phase barium titanate with a particle size of about 1 μm was added to 1 kg of industrial wastewater sludge with a water content of about 95% per ton, and mixed uniformly. The sludge system was dewatered using a physical centrifugal process, with a centrifugal speed of 10,000 rpm and an action time of 30 min. The water content of the sludge after centrifugation was reduced to about 50%, and the weight was reduced by about 95%.

[0076] The tetragonal phase barium titanate with a particle size of about 1 μm was added to 1 kg of industrial wastewater sludge with a water content of about 95% per ton, and mixed uniformly. The sludge system was dewatered using a physical centrifugal process, with a centrifugal speed of 10,000 rpm and an action time of 30 min. The water content of the sludge after centrifugation was reduced to about 50%, and the weight was reduced by about 95%.

[0077] Comparative Example 6

[0078] The tetragonal phase barium titanate with a particle size of about 1 μm was added to 1 kg of industrial wastewater sludge with a water content of about 95% per ton, and mixed uniformly. The sludge system was dewatered using a physical centrifugal process, with a centrifugal speed of 10,000 rpm and an action time of 30 min. The water content of the sludge after centrifugation was reduced to about 50%, and the weight was reduced by about 95%.

[0079] The tetragonal phase barium titanate with a particle size of about 1 μm was added to 1 kg of industrial wastewater sludge with a water content of about 95% per ton, and mixed uniformly. The sludge system was dewatered using a physical centrifugal process, with a centrifugal speed of 10,000 rpm and an action time of 30 min. The water content of the sludge after centrifugation was reduced to about 50%, and the weight was reduced by about 95%.

[0080] The above has described the present invention and its embodiments in a schematic manner, which is not restrictive, and the embodiments shown in the drawings are only one of the embodiments of the present invention, and the actual results are not limited thereto. Therefore, if a person of ordinary skill in the art is inspired thereby, without departing from the spirit of the present invention, similar structural modes and embodiments are designed without creativity, which should all belong to the protection scope of the present patent.

Claims

1. A piezoelectric method for advanced dewatering of sludge, characterized by: The piezoelectric method for deep dewatering of the sludge is based on pressure filtration and centrifugal sludge dewatering method, the pressure in the pressure filtration is 1-20 MPa, the action time is 1-5 h; the centrifugal speed is 5000-50000 rpm, the action time is 10-60 min; the piezoelectric material used in the piezoelectric method is tetragonal phase piezoelectric barium titanate which is linear, needle-shaped or rod-shaped as a whole, or has local elongated micro-nano morphology; the tip structure of the barium titanate nanowire can respond to pressure or centrifugal force during sludge treatment, and generate a local high-intensity piezoelectric field of up to 107 V / m or above in situ, which can perform electroporation on the cell membrane of microorganisms in the sludge.

2. The piezoelectric method for sludge deep dewatering according to claim 1, characterized in that: The piezoelectric material is prepared by the following method: The Na2Ti3O7 nanowire is washed to neutral, then soaked in hydrochloric acid solution for a period of time to generate H2Ti3O7 nanowire; The Na2Ti3O7 nanowire is prepared by the following method: TiO2 nanometer powder is mixed with NaOH aqueous solution, stirred for a period of time to obtain a mixed solution; the mixed solution is sealed and stored for a period of time to obtain Na2Ti3O7 nanowire; The H2Ti3O7 nanowire and Ba(OH)2·8H2O aqueous solution are reacted at 210 DEG C for 85 min to obtain BaTiO3 nanowire, i.e. piezoelectric material.

3. The piezoelectric method for sludge deep dewatering according to claim 1, characterized in that: The particle size of the piezoelectric barium titanate is 100 nm-10 μm.

4. The piezoelectric method for sludge deep dewatering according to claim 1, characterized in that: The addition amount of the piezoelectric material is 0.1-10 kg per ton of sludge, and the sludge is mixed uniformly.

5. The piezoelectric method for sludge deep dewatering according to claim 1, characterized by: The sludge in the deep dewatering of the sludge includes one or more of the following: municipal sewage sludge, industrial sewage sludge, and bottom mud deposited in natural or artificial ponds.

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