Pulse type BOM online monitoring system and method

Abstract

The invention relates to a pulse type BOM online monitoring system and method, and belongs to the technical field of water quality monitoring. The microorganism-loaded organic electrochemical transistor comprises a grid electrode, a source electrode, a drain electrode and a semiconductor material. Wherein aerobic microorganisms are loaded on the grid electrode, the source electrode and the drain electrode are connected through a semiconductor material to form a channel, and the transistor is packaged in a micro-fluidic chip to form a monitoring sensor. When the sensor works, a water sample to be detected is kept in a saturated dissolved oxygen state, constant potential is applied between the source electrode and the drain electrode of the transistor, and pulse potential is applied between the source electrode and the grid electrode. The BOM content of the water body can be reflected by measuring the output current during pulse. When the device is applied to BOM monitoring of the water body, highly integrated unmanned monitoring can be realized only by calibrating the output current of the device regularly, and the BOM concentration of the water body to be monitored can be monitored simply, conveniently, quickly and accurately in real time.

Description

Technical Field

[0001] The invention belongs to the technical field of water quality monitoring and relates to a pulsed BOM online monitoring system and method. Background Art

[0002] As raw materials and intermediate products in the chemical production process, most organic matter has biological toxicity and cumulative effects. Some organic matter has low concentration and is not easy to degrade. When the concentration of organic matter in the water environment exceeds the standard, microorganisms decompose organic matter and consume a large amount of dissolved oxygen in the water, causing aquatic organisms to die of lack of oxygen; in addition, excessive concentration of organic matter in drinking water sources will increase chloride disinfection by-products, and increase the use of coagulants and the amount of aluminum residue, all of which will bring additional harm to human health.

[0003] Biodegradable Organic Matter (BOM) refers to organic matter that can be decomposed into simple compounds (such as CO2, H2O, etc.) by microorganisms in the natural environment. It can directly represent the total amount of organic matter in the water that can be processed by microorganisms. By monitoring the BOM concentration in the water, the situation of organic pollution in the water can be reflected. At present, the main methods for BOM detection include BDOC, BOD, microbial membrane electrode, BODQ and other methods.

[0004] The principle of the BODC method is that microorganisms degrade dissolved organic matter in water and measure the difference in dissolved organic carbon before and after degradation. It requires inoculation and cultivation of microorganisms for 5 to 28 days under light-proof and constant temperature (usually 20°C) conditions, and then a total organic carbon analyzer is used to measure the difference in DOC before and after cultivation. This method can directly reflect the BOM content, but it is time-consuming and requires expensive instruments such as total organic carbon analyzers that require professional operation, and the monitoring cost is too high.

[0005] The BOD method is a commonly used method for measuring organic matter content, including BOD5, BOD10, etc. It indirectly reflects the BOM content by measuring the oxygen consumption of microorganisms when degrading organic matter. This method requires culturing microorganisms for 5 days in a dark environment at 20°C and then measuring the consumption of dissolved oxygen. The detection time is too long, the detection accuracy is poor, and the detection range is small.

[0006] The principle of the microbial membrane electrode method is that microorganisms consume oxygen, causing the dissolved oxygen concentration near the electrode to decrease. The oxygen electrode detects the change in dissolved oxygen and converts it into an electrical signal (such as current or voltage), and then converts the electrical signal into the corresponding organic matter concentration value. Compared with the BOD method, this method significantly shortens the detection time (usually a few minutes to a few hours), but has high requirements for microbial membranes, requires specific strains and a complicated activation process. The BODQ method requires anaerobic conditions, and its core sensor is large in size, has high material costs, and poor detection accuracy.

[0007] In summary, the existing BOM detection methods are either time-consuming and have poor accuracy, or have high detection costs and are difficult to operate, and cannot achieve rapid and real-time online monitoring of water BOM. Summary of the invention

[0008] In view of this, an object of the present invention is to provide a pulsed BOM online monitoring system and method to achieve simple, rapid, real-time and accurate monitoring of the BOM concentration in water.

[0009] In order to achieve the above object, the present invention provides the following technical solutions:

[0010] 1. A pulsed BOM online monitoring system, including an organic electrochemical transistor (Organic Electrochemical Transistor, OECT), a host computer, an aeration pump and a pulse generator. Among them, the gate of the organic electrochemical transistor is used to load aerobic microorganisms, a pulse voltage is applied between the gate and the source through a pulse generator, and a constant voltage is applied between the drain and the source. The host computer reads the drain-source current of the organic electrochemical transistor when the pulse voltage occurs through a signal acquisition device, and calculates the BOM concentration of the water sample to be tested. The aeration pump is used to oxygenate the water sample to be tested so that the water sample to be tested remains in a saturated dissolved oxygen state.

[0011] Furthermore, in the host computer, the BOM concentration of the water sample to be tested is calculated according to the pre-calibrated linear relationship between the BOM concentration of the water body and the drain-source current of the organic electrochemical transistor.

[0012] Furthermore, the organic electrochemical transistor is encapsulated in a microfluidic chip.

[0013] Furthermore, the system also includes a syringe pump and a filter membrane. The water sample to be tested is injected into the liquid inlet of the microfluidic chip through the syringe pump and flows through the gate of the organic electrochemical transistor; the filter membrane is arranged at the liquid inlet of the microfluidic chip to filter the microorganisms in the water sample to be tested.

[0014] 2. A method for monitoring the BOM concentration of a water body using the pulsed BOM online monitoring system, the method comprising the following steps:

[0015] 1. Obtain a water sample to be tested, take out a portion of the sample and use an aeration pump to make the portion of the sample reach a saturated dissolved oxygen state; take out the filter membrane at the liquid inlet of the microfluidic chip, inject the portion of the sample into the microfluidic chip at a constant flow rate, and at the same time apply a constant voltage to the drain and source of the organic electrochemical transistor, and apply a pulse voltage to the gate and source; when the drain-source current of the organic electrochemical transistor received by the host computer is stable, complete the bacterial inoculation of the gate of the organic electrochemical transistor, and place the filter membrane in place;

[0016] 2. Process another part of the sample into several water samples with different concentrations, inject these water samples into the inoculated microfluidic chip in turn through the syringe pump, obtain several concentration-current curves, linearly fit the several concentration-current curves, and complete the calibration of the correlation between the BOM concentration of the water body to be tested and the output current of the microfluidic chip;

[0017] 3. The calibrated online monitoring system is used for real-time monitoring of BOM concentration in the water body to be tested.

[0018] Furthermore, at regular intervals, the correlation between the BOM concentration of the water body to be measured and the output current of the microfluidic chip needs to be recalibrated, and the operations of steps 1 and 2 are performed during the recalibration.

[0019] The beneficial effects of the present invention are as follows: based on the influence of microbial activity and quantity on the gate capacitance of an organic electrochemical transistor, the present invention proposes a pulsed BOM online monitoring system, which can achieve high-sensitivity detection of short-term microbial changes by keeping the water sample to be tested in a saturated dissolved oxygen state and applying a pulse voltage between the gate and source of the organic electrochemical transistor to eliminate the influence of the redox reaction of the semiconductor layer, thereby achieving real-time monitoring of the BOM concentration of the water body. When the present invention is applied to water body BOM monitoring, there is no need to obtain additional strains for inoculation, and only the device output current needs to be calibrated regularly, so that highly integrated unmanned monitoring can be achieved, and the BOM concentration of the water body to be tested can be monitored simply, quickly, in real time and accurately.

[0020] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0022] Figure 1 A schematic diagram of the working process of a pulsed BOM online monitoring system provided by an embodiment of the present invention;

[0023] Figure 2 For monitoring sensor structure;

[0024] Figure 3 is the pulse voltage waveform;

[0025] Figure 4 The output current waveform of the sensor under different sodium acetate concentrations;

[0026] Figure 5 Shown are the fitting results of the sensor output current at different sodium acetate concentrations. DETAILED DESCRIPTION

[0027] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0028] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order 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 actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0029] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0030] The pulsed BOM online monitoring system provided by one embodiment of the present invention comprises: a monitoring sensor, an aeration pump, a pulse generator and a host computer. The aeration pump is used to aerate the water sample to be tested so that the water sample to be tested is kept saturated with dissolved oxygen; the pulse generator is used to provide a pulse voltage to the monitoring sensor to eliminate the influence of the redox reaction of the sensor semiconductor layer on the concentration monitoring; during the process of the water sample to be tested continuously feeding the monitoring sensor, the host computer obtains the output current of the sensor under the pulse voltage through the signal acquisition device, visualizes the curve of the output current, and solves the BOM concentration value of the water sample to be tested.

[0031] like Figure 2As shown, the monitoring sensor includes a microfluidic chip and an OECT encapsulated in the microfluidic chip. Among them, the OECT includes a gate, a source, a drain and a semiconductor material, the source and the drain are connected by the semiconductor material to form a channel, and the source and the drain are both gold interdigital electrodes. The gate of the OECT is used to load aerobic microorganisms. Among them, the semiconductor channel is formed by coating 5μL of PEDOT on the surface of the source and drain gold interdigital electrodes, spin coating at 4000rpm for 30s, and then annealing at 110℃ for 20min.

[0032] like Figure 1 As shown, when the system is working, water samples are injected into the monitoring sensor through the injection pump, a constant potential is applied between the source and drain of the sensor, a pulse potential is applied between the source and the gate, and the current between the drain and the source during the pulse is collected to obtain the BOM content of the water body.

[0033] The following embodiment takes sodium acetate as an example to illustrate the application of the pulsed BOM online monitoring system proposed by the present invention in BOM monitoring.

[0034] First, prepare an organic solution containing microorganisms to simulate the environment of the water body to be tested in actual applications. Specifically, select any BOD5 strain and disperse it in 100mL of aqueous solution, then take 5mL of the strain dispersion and add it to 100mL of 100mgL -1 The solvent is 0.01 M PBS solution, and the pH is 7.0.

[0035] Then, the water sample was aerated to reach saturated dissolved oxygen state, and the sample was injected at a rate of 20 μL / min, and the microorganisms were inoculated on the OECT gate. At the same time, a constant voltage of 0.3 V was applied to the source and drain of the OECT, and a pulse voltage (such as Figure 3 As shown in the figure, the pulse amplitude is 0.8V, the pulse time is 10s, and the pulse interval is 100s). When the output current of the monitoring sensor is stable, the bacterial inoculation is completed.

[0036] Sodium acetate solutions of different concentrations were prepared. Before the water sample was injected, a 0.45 μm thick MCE filter membrane was set at the front of OECT to prevent interference from microorganisms in the water sample. The sample was continuously injected into OECT and the output current of OCET was collected. During the injection, an aeration pump was used to aerate the water sample to maintain the saturated dissolved oxygen state.

[0037] like Figure 4 The output current curve of the sensor displayed by the host computer under different concentrations of sodium acetate solution is shown. By further linear fitting of the output current under different concentrations of sodium acetate, the linear relationship between the output current and the sodium acetate concentration can be obtained, and the correlation coefficient R 2is 0.978, such as Figure 5 Therefore, according to the linear relationship between the output current and the sodium acetate concentration, the BOM concentration of the water sample to be tested can be calculated from the output current.

[0038] It should be noted that, although the above embodiment only shows a single sodium acetate organic solution, in actual applications, water bodies contain multiple BOMs, but the matrix and BOM composition of different water bodies have certain characteristics, and all follow the relationship of high concentration and low current. Therefore, when performing actual water body detection, the BOM value corresponding to the specific output current of the monitoring sensor can be calibrated by the traditional method for the BOM value of the actual sample, and the calibrated linear relationship can be saved in the host computer, and can be directly applied during subsequent real-time monitoring.

[0039] In summary, the present invention provides a pulsed BOM online monitoring system, which can monitor the BOM concentration of a water body to be tested simply, quickly, in real time and accurately.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A pulsed BOM online monitoring system, characterized in that: The device comprises an organic electrochemical transistor, a host computer, an aeration pump and a pulse generator; the gate of the organic electrochemical transistor is used to load aerobic microorganisms; a pulse voltage is applied between the gate and the source of the organic electrochemical transistor through the pulse generator, and a constant voltage is applied between the drain and the source; the host computer reads the drain-source current of the organic electrochemical transistor when the pulse voltage occurs through a signal acquisition device, and calculates the BOM concentration of the water sample to be tested; the aeration pump is used to oxygenate the water sample to be tested, so that the water sample to be tested is kept in a saturated dissolved oxygen state.

2. The pulsed BOM online monitoring system according to claim 1 is characterized in that: In the host computer, the BOM concentration of the water sample to be tested is calculated according to the pre-calibrated linear relationship between the BOM concentration of the water body and the drain-source current of the organic electrochemical transistor.

3. The pulsed BOM online monitoring system according to claim 1 is characterized in that: The organic electrochemical transistor is packaged in a microfluidic chip.

4. The pulsed BOM online monitoring system according to claim 3 is characterized in that: The system also includes an injection pump and a filter membrane; the water sample to be tested is injected into the liquid inlet of the microfluidic chip through the injection pump and flows through the gate of the organic electrochemical transistor; the filter membrane is arranged at the liquid inlet of the microfluidic chip to filter the microorganisms in the water sample to be tested.

5. A BOM online monitoring method based on the system according to any one of claims 1 to 4, characterized in that: The method comprises: obtaining a water sample to be tested, taking out a part of the sample and making the part of the sample reach a saturated dissolved oxygen state through an aeration pump; taking out a filter membrane at a liquid inlet of a microfluidic chip, injecting the part of the sample into the microfluidic chip at a constant flow rate, and applying a constant voltage to the drain and source of an organic electrochemical transistor, and applying a pulse voltage to the gate and the source; when the drain-source current of the organic electrochemical transistor received by the host computer is stable, completing the bacterial species inoculation of the gate of the organic electrochemical transistor, and placing the filter membrane in place; Another part of the sample is processed into several water samples with different concentrations, and these several water samples are sequentially injected into the inoculated microfluidic chip through the injection pump to obtain several concentration-current curves, and the several concentration-current curves are linearly fitted to complete the calibration of the correlation between the BOM concentration of the water body to be tested and the output current of the microfluidic chip; The calibrated online monitoring system is used for real-time monitoring of BOM concentration in the water body to be tested.

6. The method according to claim 5, characterized in that At regular intervals, the correlation between the BOM concentration of the water body to be tested and the output current of the microfluidic chip needs to be recalibrated.

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