阅读说明：本技术 一种bod测量智能传感器 (BOD measures intelligent sensor ) 是由 刘鸿 徐泽宇 宋诚 赵迎 殷逢俊 王厦 于 2021-07-27 设计创作，主要内容包括：本发明涉及一种BOD测量智能传感器,属于微生物电化学领域,包括阳极室、阴极室、底座；所述阳极室、阴极室均设置在底座上；所述阳极室上设有阳极换液孔、阳极导热柱；所述阴极室上设有阴极换液孔、阴极导热柱；所述底座内设置热交换系统和温控系统；所述阳极导热柱及所述阴极导热柱连接至热交换系统,所述温控系统检测并调节热交换系统的换热。本发明不需外部恒温箱,通过所述温控系统和热交换系统,实现精确的温度控制,使得传感器工作在库伦效率最佳的温控点,建立库伦效率温度特性曲线结合精确计算模型消除不同传感器测量差异,提高测量准确度和一致性。(The invention relates to an intelligent BOD measuring sensor, which belongs to the field of microbial electrochemistry and comprises an anode chamber, a cathode chamber and a base; the anode chamber and the cathode chamber are both arranged on the base; an anode liquid changing hole and an anode heat conducting column are arranged on the anode chamber; the cathode chamber is provided with a cathode liquid exchange hole and a cathode heat conduction column; a heat exchange system and a temperature control system are arranged in the base; the anode heat-conducting column and the cathode heat-conducting column are connected to a heat exchange system, and the temperature control system detects and adjusts heat exchange of the heat exchange system. According to the invention, an external thermostat is not needed, and the temperature control system and the heat exchange system are used for realizing accurate temperature control, so that the sensor works at a temperature control point with the optimal coulombic efficiency, the coulombic efficiency temperature characteristic curve is established, the measurement difference of different sensors is eliminated by combining with an accurate calculation model, and the measurement accuracy and the measurement consistency are improved.)

1. A BOD measurement smart sensor, characterized by: comprises an anode chamber, a cathode chamber and a base; the anode chamber and the cathode chamber are both arranged on the base; an anode liquid changing hole and an anode heat conducting column are arranged on the anode chamber; the cathode chamber is provided with a cathode liquid exchange hole and a cathode heat conduction column; a heat exchange system and a temperature control system are arranged in the base; the anode heat-conducting column and the cathode heat-conducting column are connected to a heat exchange system, and the temperature control system detects and adjusts heat exchange of the heat exchange system.

2. The BOD measurement smart sensor of claim 1, wherein: the anode chamber comprises an anode main body, a first sealing rubber gasket and an anode electrode; the anode electrode is arranged in the anode main body through the first sealing rubber gasket; and an anode cover plate is arranged on one side of the anode main body, which is far away from the cathode chamber.

3. The BOD measurement smart sensor of claim 1, wherein: the cathode chamber comprises a cathode main body, a second sealing rubber gasket and a cathode electrode; the cathode electrode is arranged in the cathode main body through the second sealing rubber gasket, and a cathode cover plate is arranged on one side, far away from the anode chamber, of the cathode main body.

4. The BOD measurement smart sensor of claim 1, wherein: the cathode chamber is connected with the anode chamber through a proton membrane arranged in a third sealing rubber gasket.

5. The BOD measurement smart sensor of claim 1, wherein: the heat exchange system comprises a cold-end heat-conducting plate, a semiconductor refrigerator, a hot-end heat-conducting plate, fins and a temperature sensor; the anode heat-conducting column and the cathode heat-conducting column are both arranged on the same side of the cold-end heat-conducting plate, and the other side of the cold-end heat-conducting plate is connected with the hot-end heat-conducting plate through a semiconductor refrigerator; the temperature sensor is arranged on the cold end heat-conducting plate, and the fins are arranged on the hot end heat-conducting plate.

6. The BOD measurement smart sensor of claim 5, wherein: the hot end heat-conducting plate is L-shaped and is used for mounting the fins.

7. The BOD measurement smart sensor of claim 1, wherein: the temperature control system comprises a circuit board which is separated from the heat exchange system through a heat insulation plate; and the circuit board is integrated with an MCU external circuit, a low-pass filter circuit, a data acquisition circuit, a low-power consumption MCU circuit and a communication circuit which are sequentially connected in series.

8. The BOD measurement smart sensor of claim 1, wherein: the anode heat-conducting column and the cathode heat-conducting column are formed by processing aluminum profiles, an oxalic acid method is adopted for anodic oxidation for 3.5 hours, a compact aluminum oxide film with the thickness not less than 40um is formed on the upper surface of the heat-conducting column, the heat-conducting column is boiled in boiling water for more than 30 minutes, and the pores of the aluminum oxide film are sealed.

9. The BOD measurement smart sensor of claim 2, wherein: the anode electrode is formed by compounding carbon cloth which is cultured to generate a microorganism electroactive film and a steel mesh electrode.

10. The BOD measurement smart sensor of claim 3, wherein: the cathode electrode is formed by compounding carbon cloth covered by fixed catalyst and waterproof paint with a steel mesh electrode.

Technical Field

The invention belongs to the field of microbial electrochemistry, and relates to an intelligent BOD (biochemical oxygen demand) measurement sensor.

Background

A Microbial Fuel Cell (MFC) is a device that converts chemical energy of organic substances contained in wastewater into electric energy. The working process of the existing BOD measuring instrument based on the microbial fuel cell can be summarized as that anode organic matters generate protons and electrons under the action of the oxidative decomposition of microbes, the electrons reach an anode through an extracellular electron transfer mechanism and reach a cathode through an external circuit, and meanwhile, the protons in the electrolyte are transferred from an anode chamber to the cathode under the drive of electric field force and concentration difference; electrons and protons undergo a reduction reaction with an electron acceptor at the cathode. The BOD measurement principle is that an external circuit is designed, an anode and a cathode are connected, electric signals including voltage, current, electric quantity and the like are obtained according to the relation of response of components of a substance to be measured or the concentration rule of the substance, and the BOD index of water quality is quantitatively or qualitatively analyzed. Experiments show that the higher the temperature is in the range of 20-40 ℃, the better the electricity generating effect of the electroactive microorganisms is, and the improvement of the working temperature in a certain range has a promoting effect on the electricity generation of the electroactive microorganisms. In the existing instruments, a microbial fuel cell is arranged in a constant temperature box, the temperature of the constant temperature box is changed, the working temperature is set, and an external signal collector is connected with a computer to form a measuring system. The anode electroactive microorganism of the microbial fuel cell device is positioned in a closed anaerobic container made of non-metallic materials, a heat exchange system of the incubator mainly exchanges heat with internal air through an incubator temperature control system and a heat exchanger, the internal air of the incubator is transferred to the inside of the device shell to exchange heat, the efficiency is very low, a large temperature difference exists between the internal air and the temperature in the incubator, and all BOD measuring instruments do not realize accurate measurement and control of the environmental temperature in the anode electroactive microorganism of the device at present. In order to improve the flux of measurement, a plurality of microbial fuel cells are generally added, the requirement on the space of the incubator is higher, the temperature of the whole internal space is controlled by adopting a constant temperature system with higher power, heat is transferred through the air in the incubator, the energy utilization efficiency is very low, the energy consumption, the volume and the weight of the incubator are further increased, and the incubator is not convenient to carry. Taking a four-channel measuring system as an example, the total mass exceeds 10 Kg. Once the instrument is shaped, more devices cannot be flexibly configured for measurement according to the requirement due to the limitation of the incubator, and the BOD distributed multipoint in-situ measurement of the water quality is not facilitated. On the other hand, the BOD tester based on the existing microbial fuel cell is provided with a plurality of microbial fuel cells in the same incubator, and the difference lies in that the microbial electroactive microbial population of each anode is formed, the thickness and the metabolic condition of the formed biological membrane are different, and the migration diffusion rate of electrons and protons is also influenced by temperature, which shows that the internal resistance (activation internal resistance, ohmic internal resistance and concentration internal resistance) of the cell is different and obviously changes along with the temperature, the coulombic efficiency and the optimal working temperature are also different, and the existing measuring instrument or system does not consider the influence factors of the coulombic efficiency and the temperature.

The invention aims to overcome the problems and designs an intelligent BOD (biochemical oxygen demand) measurement sensor integrating a constant temperature function, signal acquisition and processing and wireless transmission into a whole to realize constant temperature control of the environment in an electroactive microorganism. By accurately controlling the environmental temperature in the electroactive microorganism, the coulombic efficiency of the anode microorganism is further improved, the temperature control precision and accuracy of the environment in the anode are improved, an accurate calculation model of the coulombic efficiency related to a temperature factor can be established, different optimal temperature working points are set for different sensors, higher-accuracy measurement is realized through a compensation calculation model, and the measurement consistency of the different sensors is improved; the data acquisition and transmission functions are integrated, data acquisition and wireless transmission can be realized, and the low power consumption, high integration, small volume and intellectualization of the system are more beneficial to portability and distributed measurement.

Disclosure of Invention

In view of the above, the present invention aims to provide an intelligent BOD measuring sensor, which does not require an external thermostat, and has an in-band environmental heat exchange and temperature control system, and the temperature control system accurately measures and controls the environmental temperature in the electroactive microorganisms on the anode carbon cloth, thereby reducing the volume and the energy consumption; an accurate calculation model of coulomb efficiency related to temperature factors is established, different optimal temperature working points are set for different sensors, measurement with higher accuracy is achieved through the compensation calculation model, and measurement consistency of different sensors is improved.

In order to achieve the purpose, the invention provides the following technical scheme:

an intelligent BOD measuring sensor comprises an anode chamber, a cathode chamber and a base; the anode chamber and the cathode chamber are both arranged on the base; an anode liquid changing hole and an anode heat conducting column are arranged on the anode chamber; the cathode chamber is provided with a cathode liquid exchange hole and a cathode heat conduction column; a heat exchange system and a temperature control system are arranged in the base; the anode heat-conducting column and the cathode heat-conducting column are connected to a heat exchange system, and the temperature control system detects and adjusts heat exchange of the heat exchange system. The temperature control system and the heat exchange system realize accurate temperature control, so that the sensor works at a temperature control point with the optimal coulombic efficiency, the measurement difference of different sensors is eliminated by combining the coulombic efficiency temperature characteristic curve with an accurate calculation model, and the measurement consistency is improved.

Optionally, the anode chamber includes an anode main body, a first sealing rubber gasket, and an anode electrode; the anode electrode is arranged in the anode main body through the first sealing rubber gasket; and an anode cover plate is arranged on one side of the anode main body, which is far away from the cathode chamber.

Optionally, a second sealing rubber gasket and a cathode electrode; the cathode electrode is arranged in the cathode main body through the second sealing rubber gasket, and a cathode cover plate is arranged on one side, far away from the anode chamber, of the cathode main body.

Optionally, the cathode chamber and the anode chamber are connected through a proton membrane arranged in a third sealing rubber gasket.

Optionally, the heat exchange system comprises a cold-end heat-conducting plate, a semiconductor refrigerator, a hot-end heat-conducting plate, fins and a temperature sensor; the anode heat-conducting column and the cathode heat-conducting column are both arranged on the same side of the cold-end heat-conducting plate, and the other side of the cold-end heat-conducting plate is connected with the hot-end heat-conducting plate through a semiconductor refrigerator; the temperature sensor is arranged on the cold end heat-conducting plate, and the fins are arranged on the hot end heat-conducting plate.

Optionally, the hot-end heat-conducting plate is L-shaped and used for mounting the fins.

Optionally, the temperature control system includes a circuit board, and the circuit board is separated from the heat exchange system by a heat insulation board; the circuit board is integrated with an MCU external circuit, a low-pass filter circuit, a data acquisition circuit, a low-power consumption MCU circuit and a communication circuit which are sequentially connected in series.

Optionally, the anode heat-conducting column and the cathode heat-conducting column are formed by processing aluminum profiles, an oxalic acid method is adopted for anodic oxidation for 3.5 hours, a compact alumina film with the thickness not less than 40um is formed on the upper surface of the heat-conducting column, boiling is carried out in boiling water for more than 30 minutes, and pores of the alumina film are sealed.

Optionally, the anode electrode is formed by combining carbon cloth and a steel mesh electrode after a microbial electroactive membrane is generated by culture.

Optionally, the cathode electrode is formed by combining a carbon cloth covered by a fixed catalyst and a waterproof coating with a steel mesh electrode.

The invention designs a temperature-controllable BOD (biochemical oxygen demand) measurement intelligent sensor, wherein liquid in an anode chamber and liquid in a cathode chamber of a reactor are contacted through the end surfaces of an anode heat-conducting column and a cathode heat-conducting column, heat-conducting silicone grease is communicated with the other end surfaces of the anode heat-conducting column and the cathode heat-conducting column to exchange heat with a cold-end heat-conducting plate of a semiconductor refrigerator, the cold-end heat-conducting plate exchanges heat with the cold end of the semiconductor refrigerator, the hot end of the semiconductor exchanges heat with a hot-end heat-conducting plate, and the hot-end heat-conducting plate exchanges heat with a fin arranged outside the sensor. The NTC temperature sensor is arranged in the cold-end heat-conducting plate and used for detecting the cold-end temperature, and the internal temperature is sensed through the cold-end heat-conducting plate, the anode heat-conducting column and the cathode heat-conducting column.

According to the sensed environmental temperatures in the anode chamber and the cathode chamber: when interior ambient temperature is higher than outside ambient temperature, outside temperature control system refrigeration, inside heat is derived through positive pole heat conduction post, negative pole heat conduction post, and when interior ambient temperature is less than outside temperature, outside temperature control system heating is leading-in the heat through the cold junction heat-conducting plate, through PID temperature control algorithm, guarantees that interior ambient temperature accurate control is at the temperature of settlement, ensures the best performance of sensor. An external circuit, a filter circuit, a data acquisition circuit, a MCU (micro control unit) and related embedded software and a wireless transceiver circuit are designed and integrated on the reactor, wherein a wireless network can adopt WIFI (wireless fidelity), Bluetooth, Zigbee or other wireless networks, so that an intelligent BOD (biochemical oxygen demand) measurement sensor is formed. BOD measurement and analysis software is compiled, the BOD measurement and analysis software is operated on handheld terminals such as mobile phones and tablets, and wireless transmission signals of a plurality of sensors are received through a wireless receiving device to form the portable measuring instrument. A plurality of sensors are used to form a BOD distributed measurement system through WIFI and Zigbee networks, and a wired network or a 4G/5G wireless network is accessed through a local repeater/gateway to form a distributed BOD water quality monitoring Internet of things system.

According to the electrochemical reaction mechanism of the electroactive microorganism, the recovered electric quantity Q is calculated firstly_rComprises the following steps:

wherein Q_rRepresents the amount of recovered electricity, t represents the time for which the reaction proceeded, and I is the current of the external circuit.

The electric quantity of the substrate containing the organic matters capable of being degraded by the microorganisms is as follows:

wherein Q represents the quantity of electricity contained in the substrate, F represents the Faraday constant, and V_ANRepresenting the volume of the substrate in the anode compartment, BOD representing the concentration of organic matter in the microbially degradable substrate,the molar mass of oxygen consumed for the reduction reaction is equal to 32, N_eThe number of electrons required to consume 1 mole of oxygen is equal to 4.

The ratio of the quantity of electricity recovered by the sensor to the quantity of electricity contained in the substrate of the anode compartment is defined as the coulombic efficiency, coulombic efficiency C_EComprises the following steps:

calculating BOD according to the recovered electric quantity_r：

Bringing (4) into (3) to obtain:

in practical engineering application, firstly, the coulomb efficiency under different temperature conditions is calculated according to experimental data and a formula (3) for each manufactured sensor by an experimental method, and relevant data are solidified in the sensor. In actual use, firstly, the BOD obtained by calculating the recovered electric quantity is adopted in step (4)_rAnd (5) accurately calculating the BOD value of the substrate according to the measured coulomb efficiency corresponding to the internal environment temperature by adopting a formula (5).

The invention has the beneficial effects that:

the invention designs a heat exchange structure and a temperature control system, integrates a data acquisition and signal processing circuit and an MCU circuit, realizes the miniaturization, low power consumption, high integration and intellectualization of a BOD measuring device, integrates a wireless communication function, forms an intelligent BOD measuring sensor, and can be used for multipoint distributed measurement of the Internet of things.

The invention establishes a temperature compensation model of the measured value through accurate temperature control. Due to the temperature tolerance of the electroactive microorganisms, the tolerance temperature range is generally 20 ℃ to 40 ℃. The difference exists in the preparation process of each electroactive microbial electrode material, such as the difference of microbial population structure, quantity and thickness of formed microbial membranes, the difference in the manufacturing of carbon cloth and a conductive electrode, and the difference also exists in the migration diffusion rate of electrolyte and proton exchange membrane protons, which shows that the internal resistance (activation internal resistance, ohm internal resistance and concentration internal resistance) of the battery is different and obviously changes along with the temperature, after each sensor is manufactured, the coulomb efficiency temperature characteristic curve of each sensor is established through an experimental method, the compensation curve is stored on a circuit in each sensor, and when the electroactive microbial electrode material is actually used, the accuracy of the electroactive microbial electrode material is further improved through the compensation curve and the measurement consistency of different sensors is further improved.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the means of the instrumentalities and combinations particularly pointed out hereinafter.

Drawings

For purposes of promoting a better understanding of the objects, aspects and advantages of the invention, reference will now be made to the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a schematic view of the overall structure of the present invention;

FIG. 2 is an exploded view of the present invention;

FIG. 3 is a schematic view of a temperature control system of the present invention;

FIG. 4 is a circuit schematic of the present invention;

fig. 5 is a coulombic efficiency temperature characteristic of the present invention.

Reference numerals: the device comprises a power jack 1, a wireless communication antenna 2, a cathode chamber 3, an anode chamber 4, an anode liquid changing hole 5, a cathode liquid changing hole 6, an electrode contact 7, a base 8, an anode cover plate 41, an anode electrode 42, a first sealing rubber gasket 43, an anode liquid changing plug 44, an anode main body 45, an anode electrode spring thimble contact 46, an anode heat-conducting column 47, a proton exchange membrane 9, a third sealing rubber gasket 10, a cathode heat-exchanging plug 31, a cathode main body 32, a second sealing rubber gasket 33, a cathode electrode 34, a cathode cover plate 35, a cathode electrode spring thimble contact 36, a cathode heat-conducting column 37, a base shell 81, a cold-end heat-conducting plate 82, a semiconductor refrigerator 83, cold-end and hot-end heat-insulating plates 84, hot-end heat-conducting plates 85, 86, a circuit board 87, an NTC temperature sensor 88, a heat-radiating fin 89 and a base cover plate 810.

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention in a schematic way, and the features in the following embodiments and examples may be combined with each other without conflict.

Wherein the showings are for the purpose of illustrating the invention only and not for the purpose of limiting the same, and in which there is shown by way of illustration only and not in the drawings in which there is no intention to limit the invention thereto; to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.

The same or similar reference numerals in the drawings of the embodiments of the present invention correspond to the same or similar components; in the description of the present invention, it should be understood that if there is an orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "front", "rear", etc., based on the orientation or positional relationship shown in the drawings, it is only for convenience of description and simplification of description, but it is not an indication or suggestion that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes, and are not to be construed as limiting the present invention, and the specific meaning of the terms may be understood by those skilled in the art according to specific situations.

Referring to fig. 1 to 5, an intelligent BOD measuring sensor is shown in fig. 1, which mainly comprises a cathode chamber 3, an anode chamber 4, and a base 8. An anode liquid changing hole 5 and a cathode liquid changing hole 6 are designed at the top of the anode chamber 4, signal electrodes of the anode chamber 4 and the cathode chamber 3 are connected to an electrode contact 7, the electrode contact 7 is connected with an anode electrode spring thimble contact 46 and a cathode electrode spring thimble contact 36 in the ABS base 8, and signals are connected to a circuit board 8 arranged in the ABS base 8 through conducting wires. The base 8 is internally provided with a heat exchange system and a temperature control system as shown in fig. 3, and an electric circuit as shown in fig. 4. The whole sensor is powered through the power jack 1 on the bottom box 8, and the wireless antenna 2 is installed on the bottom box 8, so that wireless communication is realized. The cathode compartment 3, the anode compartment 4 and the base 8 are of modular design to facilitate quick assembly.

The intelligent sensor designed in the embodiment is developed according to the explosion diagram shown in fig. 2, and corresponding components are designed to form an intelligent sensor device. Wherein the carbon cloth in the anode chamber 4 is cultured to generate a microbial electroactive film and then is compounded with a steel mesh electrode to form an anode electrode 42, and the anode chamber 4 consists of an anode cover plate 41, the anode electrode 42, a first sealing rubber gasket 43, an anode main body 45, an anode liquid changing plug 44 and an anode heat-conducting column 47; the carbon cloth is compounded with a steel mesh through fixing a catalyst and a waterproof coating to form a cathode electrode 34, and the cathode electrode 34, a cathode cover plate 35, a second sealing rubber gasket 33, a cathode main body 32 and a cathode heat exchange plug 31 form a cathode chamber 3; the anode chamber 4 and the cathode chamber 3 are assembled with a proton exchange membrane 9 and a third sealing rubber gasket 10. The base 8 mainly comprises a heat exchange structure component, a circuit board 87 and a shell, liquid in the anode chamber 4 and the cathode chamber 3 contacts with the anode heat-conducting column 47, one end face of the cathode heat conduction column 36, the other end of the anode heat conduction column 47 and the other end of the cathode heat conduction column 36 are in contact with one face of the cold-end heat conduction plate 82 through heat conduction silicone grease, an NTC temperature sensor 88 is arranged in an opening in the cold-end heat conduction plate 82, the other face of the cold-end heat conduction plate 82 is in contact with the cold end of the semiconductor refrigerator 83, the heat conduction silicone grease is smeared between the contact faces to ensure good heat conduction, a cold-end and hot-end heat insulation plate 84 is designed on the periphery of the semiconductor refrigerator 83 to isolate heat radiation of the cold end and the hot end, the semiconductor refrigerator 83 is in contact with a hot-end heat conduction plate 85, the heat conduction silicone grease is smeared between the semiconductor refrigerator 83 and the hot-end heat conduction plate to ensure good heat conduction, the hot-end heat conduction plate 85 is made into an L shape, and a fin heat radiation fin 89 is installed on one side of the L shape to exchange heat with outside air; design external circuit between anode electrode 42 and cathode electrode 34, design data acquisition, signal processing and MCU circuit, realize external circuit signal acquisition and processing, the design is based on the bluetooth, WIFI and zigBee wireless transceiver circuit, design RS485 circuit and be used for intelligent system's wired communication, debugging and parameter configuration, finally design into circuit board 87 and arrange in inside base 8, upper portion design heat insulating board 86 avoids the heat transfer of circuit to hot junction heat-conducting plate 85 on, thereby base apron 810 and base shell 81 combine to constitute intelligent sensor base 8, install wireless communication antenna 2 on the shell, install external power jack 1.

The heat exchange and temperature control system in this embodiment is shown in fig. 3. The anode heat-conducting column 47 and the cathode heat-conducting column 36 are processed by aluminum profiles, then the anode oxidation is carried out for 3.5 hours by adopting an oxalic acid method, a compact alumina film with the thickness not less than 40um is formed on the upper surface of the heat-conducting column, then the heat-conducting column is boiled in boiling water for more than 30 minutes, the pores of the alumina film are sealed, the insulation resistance of the alumina film reaches more than 1000M ohm, the alumina film with high heat conductivity and good insulation is formed after the anode oxidation, the acid and alkali resistance and the corrosion resistance are realized, and the absorption and the transfer of internal electrons through the heat-conducting column are avoided; when the NTC temperature sensor 88 detects that the internal environment temperature is lower than the set temperature, the temperature control circuit and the TEC driving circuit designed on the circuit board 87 control the semiconductor refrigerator 83 to heat, the cold end temperature rises, the liquid inside is heated through the cold end heat conduction plate 82, the anode heat conduction column 47 and the cathode heat conduction column 36, and when the internal environment temperature reaches the preset temperature, the heating is stopped; when the internal environment temperature is higher than the preset value, the semiconductor refrigerator 83 refrigerates, the cold end temperature is reduced, the internal environment temperature is cooled down through the anode heat conduction column 47, the cathode heat conduction column 36 and the cold end heat conduction plate 82 and the cold end of the semiconductor refrigerator 83, and when the temperature reaches the set point, the semiconductor refrigerator 83 stops refrigerating. The semiconductor hot end realizes heat exchange with the outside through the hot end heat-conducting plate 85 and the radiating fins 89 installed on the hot end heat-conducting plate 85. And a PID temperature control algorithm is designed in temperature control software to ensure that the internal temperature precision of the battery reaches within +/-0.1 ℃.

The design of this embodiment is as shown in fig. 4, wherein the external circuit is composed of a precise resistor of one thousandth of 1000 ohms and a precise operational amplifier with low noise, low drift and high input impedance, the output signal is filtered by a fourth-order butterworth filter composed of the precise resistor, capacitor and precise operational amplifier, the filtered signal is input to a channel of a collecting circuit composed of a dual-channel 24-bit serial SPI interface a/D converter and peripheral devices, the low-power 32-bit MCU processor circuit communicates with the a/D through the serial SPI to realize the collection of MFC signals, the MCU processor circuit processes the signals, reads the coulomb efficiency solidified to the MCU storage unit, and calculates the BOD measurement data through formula (4) and formula (5). The NTC temperature sensor and other resistors form a measuring bridge, resistance change caused by temperature change is converted into bit voltage, signal amplification and noise removal are carried out through the amplifying circuit and the filtering circuit, then the bit voltage is input into another channel of an A/D converter of a serial SPI interface of 24bit, a low-power consumption 32-bit MCU processor circuit is communicated with A/D through serial SPI, collection of NTC temperature signals is achieved, the MCU processor outputs control quantity through a PID algorithm according to set temperature and collected temperature signals, the control quantity is output to an H-bridge driving circuit of the TEC in a PWM signal mode, the size and the direction of the working current of the TEC are adjusted, and therefore accurate temperature control is achieved.

The communication with an external computer is carried out through an RS485 circuit, so that the transmission of a calculation result is realized or the external computer carries out parameter setting on the BOD intelligent sensor; also can carry out wireless transmission and carry out parameter setting to BOD intelligent sensor through the wireless transmission circuit that bluetooth, WIFI and zigBee constitute, cell-phone or other terminals receive measured data through corresponding communication interface, show, save and further processing through the APP number of going on the terminal.

In the embodiment, standard samples of known BOD are injected into the anode chambers of the two sensors, the working temperatures of the standard samples are respectively set at intervals of 2 ℃ within the range of 20-40 ℃, and the coulombic efficiency at the corresponding temperature point is calculated according to the formula (3). Experiments show that the coulombic efficiency rapidly rises in a range of 20-30 ℃, slowly falls after reaching a peak value in a range of 30-40 ℃, the microbial activity is inhibited due to temperature rise when the temperature is higher, an optimal temperature working point is arranged in the range, and the optimal temperature working points and the coulombic efficiencies of different sensors are different. FIG. 5 is a coulombic efficiency temperature characteristic of two sensors, from which one of the sensors can be seenThe optimum temperature operating point of (C) is 32 ℃ and C is the corresponding value_CECoulombic efficiency of 72%, and the optimum temperature working point of another sensor is 34 deg.C, corresponding to C_CEThe coulombic efficiency is 70.5%, and the obtained coulombic efficiency temperature curve is stored in sensor hardware. When the temperature measuring device is used, the optimal temperature working point of the sensor is selected according to the characteristic curve, and during actual measurement, the BOD measured value corresponding to the recovered electric quantity is calculated through the formula (4) firstly, and then the BOD value is accurately calculated through the formula (5), so that the measurement accuracy is improved, and the measurement consistency of different sensors is also improved.

Finally, the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions, and all that should be covered by the claims of the present invention.