An aquaculture effluent treatment system and method of use

Abstract

The application discloses an aquaculture tail water treatment system and a use method thereof, which comprises a tail water storage tank, a high-pressure treatment unit, a photocatalytic reactor and a control unit. The high-pressure treatment unit comprises a supercritical water reactor, a controller connected with the control unit, a temperature sensor installed on the supercritical water reactor, a pressure sensor and a viscosity monitor used for monitoring the viscosity of tail water. The controller is used for receiving data collected by the temperature sensor and the pressure sensor. The supercritical water reactor has two different environmental states, i.e. a subcritical water environment and a supercritical water environment. The control unit adjusts parameters in the supercritical water reactor and switches the two different environmental states. The solubility of mucus, gonad hormones, organic matters and other impurities in tail water can be enhanced, and the macromolecular network structure and proteins in the impurities can be effectively destroyed, so that more efficient decomposition is realized.

Description

Technical Field

[0001] This invention relates to a wastewater treatment system, and more particularly to an aquaculture wastewater treatment system and its usage method. Background Technology

[0002] Aquaculture refers to the production of aquatic economic animals and plants using available water areas, according to the ecological habits and environmental requirements of the cultured organisms, and employing aquaculture technologies and facilities. It is a sector of agricultural production and an important component of fisheries. Aquaculture can be classified by water area into freshwater and marine aquaculture; by cultured organisms into fish farming, shellfish farming, shrimp farming, crab farming, algae farming, etc.; and by farming methods into intensive farming, extensive farming, monoculture, polyculture, and factory farming, etc.

[0003] Currently, there are various fish farming models, but most suffer from problems such as excessively high stocking densities and extensive farming methods. Furthermore, to protect themselves from external harm or infection, fish secrete mucus composed of proteins, enzymes, and mucopolysaccharides on their body surface. This mucus is released into the aquaculture water, increasing turbidity and organic matter content.

[0004] Furthermore, during the breeding season, some fish release sex hormones, which can affect the lives of other organisms in the same waters. Additionally, the water contains large amounts of residual feed, aquatic animal excrement, and other nitrogen and phosphorus pollutants. If this wastewater is discharged directly into natural waters without treatment, it will exacerbate eutrophication in the surrounding waters, thus placing enormous pressure on the ecological environment.

[0005] In existing technologies, the treatment of wastewater from aquaculture is usually done through physical treatment methods. Suspended particulate matter and large molecular organic matter in the wastewater are removed through processes such as sedimentation, filtration, and aeration. The wastewater is then passed through activated sludge tanks and biological filters, where microorganisms decompose and transform the organic matter in the wastewater, thereby reducing the pollution level of the wastewater.

[0006] However, the existing technology has the following technical problems:

[0007] (1) Physical suspension can only remove large particulate impurities in the tailwater, but it cannot effectively remove mucus, sex hormones, digestive enzymes and other substances on the surface of fish in the tailwater, making it difficult to ensure the purity of the tailwater after treatment.

[0008] (2) In the existing technology, the organic matter in the tailwater can not be completely and effectively removed by microbial absorption and transformation, and the treatment cycle is long and the time cost is too high.

[0009] Therefore, there is an urgent need for an aquaculture wastewater treatment system and its application method to solve the technical problems existing in the above-mentioned prior art. Summary of the Invention

[0010] This invention overcomes the shortcomings of the prior art and provides an aquaculture wastewater treatment system and its usage method.

[0011] To achieve the above objectives, the technical solution adopted by the present invention is as follows: an aquaculture wastewater treatment system and method of use, comprising: a wastewater storage tank, a high-pressure treatment unit, a photocatalytic reactor, and a control unit.

[0012] The high-pressure treatment unit includes: a supercritical water reactor, a controller connected to the control unit, a temperature sensor, a pressure sensor installed on the supercritical water reactor, and a viscosity monitor for monitoring the viscosity of the effluent; the controller is used to receive data collected by the temperature sensor and the pressure sensor; the supercritical water reactor has two different environmental states: a subcritical water environment and a supercritical water environment; the control unit adjusts the parameters inside the supercritical water reactor to switch between the two different environmental states.

[0013] The tailwater storage tank, the high-pressure treatment unit, and the photocatalytic reactor are connected in series, and the tailwater storage tank is equipped with a tailwater filtration unit.

[0014] In a preferred embodiment of the present invention, the temperature of the subcritical water environment is 180-370°C and the pressure is 10-22 MPa, and the temperature and pressure values ​​of the subcritical water can be extreme values.

[0015] In a preferred embodiment of the present invention, the temperature of the supercritical water environment is greater than or equal to 374°C and the pressure is greater than 22.1 MPa.

[0016] In a preferred embodiment of the present invention, the viscosity monitor is one of a viscometer, a densitometer, a laser monitor, or a computer vision-based monitor.

[0017] In a preferred embodiment of the present invention, the temperature sensor is one of a radiation pyrometer, a fiber optic temperature sensor, or a thermocouple sensor.

[0018] In a preferred embodiment of the present invention, the pressure sensor is one of a capacitive pressure sensor, a piezoresistive pressure sensor, or a resonant pressure sensor.

[0019] In a preferred embodiment of the present invention, a first water pump is provided between the tailwater storage tank and the supercritical water reactor, and a second water pump is provided between the supercritical water reactor and the photocatalytic reactor.

[0020] In a preferred embodiment of the present invention, a method of using an aquaculture wastewater treatment system, based on the aquaculture wastewater treatment system according to any one of claims 1-7, includes the following steps:

[0021] S1. Untreated effluent undergoes sedimentation treatment in the effluent storage tank to remove particulate impurities and obtain pretreated effluent.

[0022] S2. The first water pump draws the pretreated wastewater into the supercritical water reactor. Then, the pretreated wastewater is heated to above the boiling point in the supercritical water reactor. The pressure in the supercritical water reactor is regulated by the control unit until the requirements of the subcritical water environment are met, and then heating and pressurization are stopped. This process destroys the polymer network structure of impurities in the pretreated wastewater and yields the initial treated wastewater.

[0023] S3. Increase the temperature and pressure in the supercritical water reactor to decompose the proteins in the primary treated tailwater into small molecule proteins and obtain retreated tailwater.

[0024] S4. Increase the temperature and pressure in the supercritical water reactor again to transform the subcritical water environment in the supercritical water reactor into a supercritical water environment, and oxidize the impurities contained in the reprocessed tailwater to obtain the pre-purified tailwater.

[0025] S5. The initial purified wastewater is pumped to the photocatalytic reactor by the second water pump. After being treated by ultraviolet light, it becomes purified water that meets national emission standards.

[0026] In a preferred embodiment of the present invention, the subcritical water environment includes two environmental conditions: the first environmental condition is a temperature of 180-250°C and a pressure of 10-15 MPa; the second environmental condition is a temperature of 280-370°C and a pressure of 15-22 MPa; and both can take extreme values.

[0027] In a preferred embodiment of the present invention, in step S5, a titanium dioxide catalyst with a concentration of 15-25% is added while ultraviolet light acts on the pre-purified effluent.

[0028] This invention addresses the shortcomings of the prior art and has the following beneficial effects:

[0029] (1) This invention sets up subcritical and supercritical water environments within a supercritical water reactor. During use, relying on the unique physical and chemical properties of subcritical and supercritical water, the subcritical water environment enhances the solubility of impurities such as mucus, sex hormones, and organic matter in the effluent, and effectively destroys the high-molecular network structure and proteins in these impurities, thus achieving more efficient decomposition and ensuring removal effectiveness. Simultaneously, the supercritical water environment gives the effluent good flowability similar to gas, and its density is much higher than that of gas, thus more effectively decomposing various harmful substances in the effluent into harmless substances, thereby achieving the purpose of purifying water quality and protecting the environment. This solves the problem of incomplete cleaning in existing technologies.

[0030] (2) This invention incorporates a photocatalytic reactor. During use, the wastewater treated by the supercritical water reactor is further degraded by the photocatalytic reactor, thereby catalytically decomposing residual organic matter in the wastewater. Furthermore, within the photocatalytic reactor, aided by ultraviolet light and a titanium dioxide catalyst, residual mucus, sex hormones, digestive enzymes, and other impurities in the wastewater are effectively removed. This solves the problems of long treatment time and high treatment costs in existing technologies.

[0031] (3) This invention uses the cooperation of a supercritical water reactor and a photocatalytic reactor. When in use, the supercritical water reactor can ensure that the wastewater is in a high temperature and high pressure environment during the wastewater treatment process, which can effectively destroy the special structure of impurities and some impurities that are difficult to decompose directly, thus helping to remove impurities. At the same time, the wastewater is further purified by the photocatalytic reactor, thus ensuring that the final discharged wastewater meets the national discharge standards. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of the aquaculture wastewater treatment system of the present invention;

[0034] Figure 2 This is a flowchart of the wastewater treatment steps of the present invention.

[0035] In the diagram: 1. Tailwater storage tank; 2. First water pump; 3. Supercritical water reactor; 3.1. Controller; 3.2. Temperature sensor; 3.3. Pressure sensor; 4. Second water pump; 5. Photocatalytic reactor. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein. Therefore, the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0038] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the scope of protection of this application. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0039] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art will understand the specific meaning of the above terms in this application based on the specific circumstances.

[0040] like Figure 1 As shown, an aquaculture wastewater treatment system and its usage method include: a wastewater storage tank 1, a high-pressure treatment unit, a photocatalytic reactor 5, and a control unit.

[0041] The high-pressure treatment unit includes: a supercritical water reactor 3, a controller 3.1 connected to the control unit, a temperature sensor 3.2 and a pressure sensor 3.3 installed on the supercritical water reactor 3, and a viscosity monitor for monitoring the viscosity of the effluent; the controller is used to receive data collected by the temperature sensor 3.2 and the pressure sensor 3.3. The supercritical water reactor 3 has two different environmental states: a subcritical water environment and a supercritical water environment. The control unit adjusts the parameters inside the supercritical water reactor 3 and switches between the two different environmental states.

[0042] The tailwater storage tank 1, the high-pressure treatment unit, and the photocatalytic reactor 5 are connected in series. The tailwater storage tank 1 is equipped with a tailwater filtration unit. A first water pump 2 is installed between the tailwater storage tank 1 and the supercritical water reactor 3, and a second water pump 4 is installed between the supercritical water reactor 3 and the photocatalytic reactor 5.

[0043] In a preferred embodiment, the subcritical water environment has a temperature of 180–370°C and a pressure of 10–22 MPa. The supercritical water environment has a temperature greater than or equal to 374°C and a pressure greater than 22.1 MPa.

[0044] Viscosity monitors are one type of viscometer, densitometer, laser monitor, or computer vision-based monitor. Temperature sensor 3.2 is one type of radiation pyrometer, fiber optic temperature sensor, or thermocouple sensor. Pressure sensor 3.3 is one type of capacitive pressure sensor, piezoresistive pressure sensor, or resonant pressure sensor.

[0045] In a preferred embodiment, such as Figure 2 As shown, a method for using an aquaculture wastewater treatment system includes the following steps:

[0046] S1. Untreated effluent undergoes sedimentation treatment in the effluent storage tank to remove particulate impurities and obtain pretreated effluent.

[0047] S2. The first water pump draws the pretreated wastewater into the supercritical water reactor. Then, the pretreated wastewater is heated to above the boiling point in the supercritical water reactor. The pressure in the supercritical water reactor is regulated by the control unit until the requirements of the subcritical water environment are met, and then heating and pressurization are stopped. This process destroys the polymer network structure of impurities in the pretreated wastewater and yields the initial treated wastewater.

[0048] S3. Increase the temperature and pressure in the supercritical water reactor to decompose the proteins in the primary treated tailwater into small molecule proteins and obtain retreated tailwater.

[0049] S4. Increase the temperature and pressure in the supercritical water reactor again to transform the subcritical water environment in the supercritical water reactor into a supercritical water environment, and oxidize the impurities contained in the reprocessed tailwater to obtain the pre-purified tailwater.

[0050] S5. The pre-purified effluent is pumped to the photocatalytic reactor by the second water pump. After being treated with ultraviolet light, and while the pre-purified effluent is being treated with ultraviolet light, a titanium dioxide catalyst with a concentration of 15-25% is added to obtain purified water that meets national emission standards.

[0051] In a preferred embodiment, the environmental conditions in step S2 are: temperature 180-250°C and pressure 10-15 MPa; the environmental conditions in step S3 are: temperature 280-370°C and pressure 15-22 MPa.

[0052] Example 1

[0053] In this embodiment, the final discharged effluent is determined according to the "Freshwater Pond Aquaculture Water Discharge Standard" (SCT 9101-2007) to ensure the authenticity and validity of the final data of the embodiment.

[0054] In this embodiment, the supercritical water reactor and photocatalytic reactor used are both commercially available and fully functional existing devices, belonging to common prior art; therefore, no model limitation is imposed. The control unit and controller both employ single-chip microcomputer integrated circuit systems to ensure stability during operation. A fiber optic temperature sensor, a capacitive pressure sensor, and a viscometer are used as the viscosity monitor.

[0055] In this embodiment, the concentration of titanium dioxide catalyst added to the photocatalytic reactor is 20%; the ratio of the amount added to the amount of tailwater contained in the photocatalytic reactor at that time is 1:10.

[0056] In this embodiment, the initial environmental conditions for the subcritical water environment are: temperature 200℃ and pressure 12MPa; the adjusted environmental conditions are: temperature 300℃ and pressure 18MPa. The temperature in the supercritical water environment is 380℃ and the pressure is 24MPa.

[0057] In this embodiment, the reaction time of the tailwater in the supercritical water reactor under the initial environmental conditions of subcritical water is 30 s, and the reaction time after adjustment is 20 s; the reaction time of the tailwater in the supercritical water reactor under supercritical water environmental conditions is 20 s. The reaction time of the tailwater in the photocatalytic reactor is 30 s.

[0058] After a series of actual treatment operations in Example 1, the relevant data for the effluent are shown in Table 1:

[0059] mucus 50mg / L 28.3 mg / L sex hormones 15mg / L 7.1 mg / L Digestive enzymes 30mg / L 11.6 mg / L organic matter 20mg / L 6.8 mg / L

[0060] Table 1

[0061] The purified effluent obtained in Example 1 was subjected to specialized testing and compared with the standards specified in the "Freshwater Pond Aquaculture Wastewater Discharge Standard" (SCT 9101-2007), as shown in Table 2:

[0062]

[0063]

[0064] Table 2

[0065] In summary, by using the technical solution of this application, the wastewater generated by aquaculture can be treated to obtain clean water that meets national discharge standards, thereby effectively ensuring the treatment effect and achieving the purpose of purifying water quality and protecting the environment.

[0066] Comparative Example 1

[0067] Unlike Example 1, the supercritical water reactor is always kept in a supercritical water environment, without distinguishing between subcritical and supercritical water environments, and other parameters remain unchanged.

[0068] After undergoing a series of actual treatment operations as shown in Comparative Example 1, the relevant data for the effluent are presented in Table 3.

[0069] mucus 50mg / L 50.8 mg / L sex hormones 15mg / L 15.7 mg / L Digestive enzymes 30mg / L 32.3 mg / L organic matter 20mg / L 25.9 mg / L

[0070] Table 3

[0071] The purified effluent obtained in Comparative Example 1 was subjected to specialized testing and compared with the standards specified in the "Freshwater Pond Aquaculture Wastewater Discharge Standard" (SCT 9101-2007), as shown in Table 4:

[0072] Total ammonia ≤3mg / L 3.3 mg / L Total phosphorus ≤0.5mg / L 0.51 mg / L Chemical oxygen demand ≤25mg / L 26.7 mg / L Biochemical oxygen demand ≤15mg / L 16.2 mg / L

[0073] Table 4

[0074] In summary, the absence of subcritical and supercritical water environments within a supercritical water reactor not only significantly impacts the final treatment results, preventing them from meeting emission standards, but also leads to resource waste and contradicts the social development needs of energy conservation and environmental protection.

[0075] Comparative Example 2

[0076] Unlike Example 1, a photocatalytic reactor was not used to reprocess the tailings from the supercritical water reactor, while other parameters remained unchanged.

[0077] After undergoing a series of actual treatment operations as shown in Comparative Example 2, the relevant data for the effluent are presented in Table 5.

[0078] mucus 50mg / L 48.7 mg / L sex hormones 15mg / L 15.4 mg / L Digestive enzymes 30mg / L 33.9 mg / L organic matter 20mg / L 21.3 mg / L

[0079] Table 5

[0080] The purified effluent obtained in Comparative Example 2 was subjected to specialized testing and compared with the standards stipulated in the "Freshwater Pond Aquaculture Wastewater Discharge Standard" (SCT 9101-2007), as shown in Table 6:

[0081] Total ammonia ≤3mg / L 2.8 mg / L Total phosphorus ≤0.5mg / L 0.48 mg / L Chemical oxygen demand ≤25mg / L 25.6 mg / L Biochemical oxygen demand ≤15mg / L 15.7 mg / L

[0082] Table 6

[0083] In summary, if a photocatalytic reactor is not used for further effective treatment of the wastewater, the final treatment result will be affected. This will not only prevent the wastewater from meeting discharge standards, but also fail to guarantee the thoroughness of the treatment, thus wasting resources and failing to meet the social development needs of energy conservation and environmental protection.

[0084] Comparative Example 3

[0085] Unlike Example 1, no titanium dioxide catalyst was added during the stage of decomposing impurities in the photocatalytic reactor, while other parameters remained unchanged.

[0086] After a series of actual treatment operations in Comparative Example 3, the relevant data for the effluent are shown in Table 7:

[0087] mucus 50mg / L 13.7 mg / L sex hormones 15mg / L 8.9 mg / L Digestive enzymes 30mg / L 9.4 mg / L organic matter 20mg / L 11.7 mg / L

[0088] Table 7

[0089] After testing, it was found that the wastewater required more time to pass through the photocatalytic reactor before it could meet national emission standards.

[0090] The purified effluent obtained in Comparative Example 3 was then subjected to specialized testing and compared with the standards stipulated in the "Freshwater Pond Aquaculture Wastewater Discharge Standard" (SCT 9101-2007), as shown in Table 8:

[0091] Total ammonia ≤3mg / L 2.5 mg / L Total phosphorus ≤0.5mg / L 0.48 mg / L Chemical oxygen demand ≤25mg / L 24.6 mg / L Biochemical oxygen demand ≤15mg / L 13.4 mg / L

[0092] Table 8

[0093] In summary, while it's possible to achieve national emission standards for effluent without adding titanium dioxide catalyst during the photocatalytic reactor decomposition stage, the reaction time increases, leading to higher resource consumption and a heavier treatment burden. Furthermore, even though the final result meets emission standards without adding titanium dioxide catalyst, a comparison with the data obtained after adding it reveals that the treatment effect is superior and more beneficial for long-term social development, demonstrating promising potential.

[0094] In use, the wastewater is first stored in a wastewater storage tank 1 for sedimentation treatment, thereby preliminarily treating particulate impurities and residual fish food contained in the wastewater. The preliminarily treated wastewater is drawn into a supercritical water reactor 3 by a first water pump 2, and the wastewater in the supercritical water reactor 3 is heated and pressurized by a control unit until the supercritical water reactor 3 reaches a subcritical water environment. After a certain period of treatment reaction, the high molecular network structure and organic matter in the impurities are destroyed. Then, the temperature and pressure in the supercritical water reactor 3 are increased to decompose and remove impurities such as proteins in the wastewater. Finally, the temperature and pressure in the supercritical water reactor 3 are increased to the supercritical water environment conditions to further decompose and remove the already destroyed high molecular network structure, organic matter, proteins and other impurities.

[0095] The wastewater is then pumped to the photocatalytic reactor 6 by the second water pump 5. With the assistance of ultraviolet light and titanium dioxide catalyst, the wastewater is further treated. Finally, the treated wastewater is tested by relevant departments and discharged after meeting the national emission standards.

[0096] Based on the preferred embodiments of the present invention described above, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for treating aquaculture wastewater, comprising an aquaculture wastewater treatment system, wherein the aquaculture wastewater treatment system includes: The wastewater storage tank, high-pressure treatment unit, photocatalytic reactor, and control unit are characterized by: The high-pressure treatment unit includes: a supercritical water reactor, a controller connected to the control unit, a temperature sensor, a pressure sensor, and a viscosity monitor for monitoring the viscosity of the effluent, all installed on the supercritical water reactor. The controller receives data collected by the temperature sensor and the pressure sensor. The supercritical water reactor has two different environmental states: a subcritical water environment and a supercritical water environment. The control unit adjusts the parameters inside the supercritical water reactor to switch between the two different environmental states. The tailwater storage tank, high-pressure treatment unit, and photocatalytic reactor are connected in series, and the tailwater storage tank is equipped with a tailwater filtration unit. The aquaculture wastewater treatment method includes the following steps: S1. Untreated aquaculture wastewater undergoes sedimentation treatment in a wastewater storage tank to remove particulate impurities and obtain pretreated wastewater. S2. The first water pump draws the pretreated tailwater into the supercritical water reactor. Then, the pretreated tailwater is heated to above the boiling point in the supercritical water reactor. The pressure in the supercritical water reactor is regulated by the control unit until the environmental conditions in the supercritical water reactor reach a temperature of 180-250℃ and a pressure of 10-15MPa. Heating and pressurization are then stopped to destroy the polymer network structure of impurities contained in the pretreated tailwater and obtain the initial treated tailwater. S3. Increase the temperature in the supercritical water reactor to 280-370℃ and the pressure to 15-22MPa to decompose the proteins of impurities in the primary treatment tailwater into small molecule proteins and obtain retreated tailwater. S4. Increase the temperature and pressure in the supercritical water reactor again to transform the subcritical water environment in the supercritical water reactor into a supercritical water environment, and oxidize the impurities in the reprocessed tailwater to obtain pre-purified tailwater; wherein, the temperature of the supercritical water environment is greater than or equal to 374℃ and the pressure is greater than 22.1MPa. S5. The primary purified effluent is pumped to the photocatalytic reactor by the second water pump. After being treated with ultraviolet light, purified water that meets national emission standards is obtained. During the treatment of the primary purified effluent with ultraviolet light, a titanium dioxide catalyst with a concentration of 15-25% is added.

2. The method for treating aquaculture wastewater according to claim 1, characterized in that: The viscosity monitor is one of the following: viscometer, densitometer, laser monitor, or computer vision-based monitor.

3. The aquaculture wastewater treatment method according to claim 1, characterized in that: The temperature sensor is one of the following: a radiation pyrometer, a fiber optic temperature sensor, or a thermocouple sensor.

4. The method for treating aquaculture wastewater according to claim 1, characterized in that: The pressure sensor is one of the following: capacitive pressure sensor, piezoresistive pressure sensor, or resonant pressure sensor.

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