A remote monitoring system for water quality of secondary water supply

Abstract

This invention discloses a remote water quality monitoring system for secondary water supply systems, belonging to the field of water quality testing technology. It solves the problems of Legionella outbreaks caused by the coupling of hydraulic stagnation and high-temperature environments in secondary water supply systems, where the random distribution of pathogens in isolated pipe sections leads to spatial randomness in detection, false negatives, and high costs due to monitoring blind spots. The system includes a main control and computing module, an electrochemical impedance spectroscopy (EIS) measurement module, a microcurrent measurement module, a multi-channel switching module, a temperature sensing module, a bus power supply and communication module, and a three-electrode sensing patch. The main control and computing module coordinates and controls the operation sequence of all modules, executes EIS fitting and microcurrent trend analysis algorithms, and makes risk decisions based on the fusion results of multi-source data. This invention automatically monitors the water quality at the end of each pipeline, measures temperature, performs EIS scanning, analyzes weak metabolic currents, and fuses data to assess the risk of biofilm formation in real time, ultimately uploading early warning information.

Description

Technical Field

[0001] This invention relates to the field of water quality testing technology, and in particular to a remote monitoring system for secondary water supply quality. Background Technology

[0002] Secondary water supply is a method of supplying water to users when the pressure of the urban water supply network is insufficient to meet the water needs of hotels and large buildings. It uses facilities such as water storage tanks, booster pumps, and pipe networks to pressurize tap water and deliver it to users. It ensures a stable water supply for users, but requires regular maintenance of facilities and monitoring of water quality to prevent pollution. It is an important supplement to the urban water supply system.

[0003] Therefore, secondary water supply systems require water quality testing, which is crucial for ensuring the safety of drinking water for high-rise users. The testing primarily focuses on core indicators such as residual chlorine, turbidity, total bacterial count, and E. coli. Regular testing is necessary, and the testing institutions must be qualified. If any indicators are found to exceed standards, the water storage tanks, pipelines, and other facilities must be promptly investigated and rectified to prevent water quality deterioration due to facility contamination or improper maintenance, ensuring that the water quality meets national drinking water standards.

[0004] Coastal hotels face severe challenges to secondary water supply security during the off-season. In summer, occupancy rates at coastal tourist hotels plummet, leaving many rooms vacant and causing prolonged stagnation of water flow in their extensive water supply networks.

[0005] Meanwhile, in summer, ambient temperatures can reach over 35°C, and humidity is high. Water supply pipes installed in narrow, poorly ventilated equipment shafts are continuously baked by the surrounding high temperatures, causing the water temperature inside the pipes to rise. This coupling of low-flow-rate or even zero-flow-rate hydraulic stagnation with the high-temperature thermal environment triggers a vicious cycle. Stagnant water cannot receive fresh chlorine replenishment from the pump station, causing the initially added residual chlorine to decay rapidly under high temperatures, with the concentration quickly dropping below the safe threshold. The depletion of residual chlorine renders the water unable to continuously disinfect and inhibit the growth of microorganisms.

[0006] The suitable temperature provided ideal conditions for the reproduction of Legionella pneumophila lurking in the biofilm of the pipes, causing it to grow exponentially. The proliferation of microorganisms further consumed residual chlorine and reinforced the biofilm structure, exacerbating pipe corrosion and flow resistance, thus further deteriorating the hydraulic conditions. Although the hotel had cleaned the rooftop water tank as usual and the water quality at the pump room outlet passed the test, the breeding points of pathogens were randomly distributed in the "dead water zones" of the branch pipes in hundreds of vacant guest rooms.

[0007] Ultimately, this resulted in no abnormalities in the results of regular sampling points, but guests would clearly feel that the water quality was poor, so much so that the hotel had to take measures such as "thermal shock" disinfection of the entire hot water system at a temperature of over 60°C or high-concentration chemical flushing of all pipes.

[0008] Therefore, a remote monitoring system for secondary water supply quality is proposed to solve or alleviate the above problems. Summary of the Invention

[0009] The purpose of this invention is to address the shortcomings of existing technologies by proposing a remote monitoring system for secondary water supply quality.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] A remote water quality monitoring system for secondary water supply includes a main control and computing module, an electrochemical impedance spectroscopy (EIS) measurement module, a microcurrent measurement module, a multi-channel switching module, a temperature sensing module, a bus power supply and communication module, and a three-electrode sensing patch. The main control and computing module coordinates the operation timing of all modules, executes EIS fitting and microcurrent trend analysis algorithms, and makes risk decisions based on multi-source data fusion results. The EIS measurement module applies a series of small AC excitation signals of specific frequencies to the water body and accurately measures its response to obtain complex impedance data characterizing the interface properties. The microcurrent measurement module continuously monitors the working electrode... The generated nanoampere-level weak current changes are converted into quantifiable digital signals to reflect microbial metabolic activity. The multi-channel switching module switches on multiple sensor patches distributed in different geographical locations according to the instructions of the main control module. The temperature sensing module senses and uploads the real-time fluid temperature of the monitoring point to provide temperature compensation for electrochemical data and determine the temperature conditions for microbial growth. The bus power supply and communication module provides stable power and ensures that all monitoring data and alarm information are transmitted to the remote monitoring center. The three-electrode sensor patch directly undergoes an electrochemical reaction with the water body being measured, converting the microbial attachment and metabolic process into measurable electrical signals.

[0012] Preferably, the multi-channel address control output terminal of the main control and calculation module is connected to the address control input terminal of the multi-channel switching module; the first serial peripheral interface communication terminal of the main control and calculation module is connected to the serial peripheral interface configuration terminal of the electrochemical impedance spectroscopy measurement module; the counter electrode excitation signal output terminal of the electrochemical impedance spectroscopy measurement module is connected to the common counter electrode input terminal of the multi-channel switching module; the reference electrode signal acquisition terminal of the electrochemical impedance spectroscopy measurement module is connected to the common reference electrode input terminal of the multi-channel switching module; the working electrode signal detection terminal of the microcurrent measurement module is connected to the common working electrode input terminal of the multi-channel switching module; the analog-to-digital conversion data output terminal of the microcurrent measurement module is connected to the second serial peripheral interface communication terminal of the main control and calculation module; the internal integrated circuit data interface of the temperature sensing module is connected to the internal integrated circuit communication terminal of the main control and calculation module; the DC power output terminal of the bus power supply and communication module is connected to the power input terminal of each module; the asynchronous serial data interface of the bus power supply and communication module is connected to the universal asynchronous transceiver communication terminal of the main control and calculation module; and the multiple electrode leads of the three-electrode sensing patch are respectively connected to the corresponding channel interfaces of the multi-channel switching module.

[0013] Preferably, the main control and computing module includes a microcontroller STM32H743VIT6. The first group of general-purpose input / output ports of the microcontroller STM32H743VIT6 is configured as a multi-channel address control output terminal. The first serial peripheral interface clock signal output terminal, master input / slave output data terminal, master output / slave input data terminal, and slave selection signal output terminal of the microcontroller STM32H743VIT6 are configured as a first serial peripheral interface communication terminal. The second serial peripheral interface clock signal output terminal, master input / slave output data terminal, master output / slave input data terminal, and slave selection signal output terminal of the microcontroller STM32H743VIT6 are configured as a second serial peripheral interface communication terminal. The internal integrated circuit clock signal terminal and internal integrated circuit data signal terminal of the microcontroller STM32H743VIT6 are configured as internal integrated circuit communication terminals. The universal asynchronous transceiver (UART) transmit data terminal and receive data terminal of the microcontroller STM32H743VIT6 are configured as UART communication terminals.

[0014] Preferably, the electrochemical impedance spectroscopy measurement module includes an electrochemical front-end chip AD5940 and an operational amplifier ADA4661-2. The serial peripheral interface clock signal input terminal, master input-slave output data terminal, master output-slave input data terminal, and chip select signal input terminal of the electrochemical front-end chip AD5940 are configured as serial peripheral interface configuration terminals. The first counter electrode signal output terminal of the electrochemical front-end chip AD5940 is configured as the counter electrode excitation signal output terminal. The first reference electrode signal input terminal of the electrochemical front-end chip AD5940 is configured as the reference electrode signal acquisition terminal. The first working electrode signal input terminal of the electrochemical front-end chip AD5940 is connected to the inverting input terminal of the operational amplifier ADA4661-2 through a first resistor. The first reference electrode signal output terminal of the electrochemical front-end chip AD5940 is connected to the non-inverting input terminal of the operational amplifier ADA4661-2 through a second resistor. The output terminal of the operational amplifier ADA4661-2 is connected back to the inverting input terminal through a feedback resistor.

[0015] Preferably, the microcurrent measurement module includes a precision operational amplifier LMP7721, a high-precision analog-to-digital converter ADS1115ADS125H02, and a guard ring. The inverting input terminal of the precision operational amplifier LMP7721 is set as the working electrode signal detection terminal, and the non-inverting input terminal of the precision operational amplifier LMP7721 is used to connect to a reference voltage source. A high-resistance feedback resistor is connected between the output terminal and the inverting input terminal of the precision operational amplifier LMP7721. The output terminal of the precision operational amplifier LMP7721 is connected to the first analog signal input terminal of the high-precision analog-to-digital converter ADS1115ADS125H02. The serial peripheral interface clock signal input terminal, data output terminal, data input terminal, and chip select signal input terminal of the high-precision analog-to-digital converter ADS1115ADS125H02 are set as analog-to-digital conversion data output terminals. The guard ring is a printed circuit board conductive ring surrounding the inverting input terminal of the precision operational amplifier LMP7721, and the guard ring is connected to the inverting input terminal of the precision operational amplifier LMP7721.

[0016] Preferably, the multi-channel switching module includes an analog multiplexer ADG1419, wherein the address signal input terminal of the analog multiplexer ADG1419 is configured as an address control input terminal, the common pair terminal of the analog multiplexer ADG1419 is configured as a common pair electrode input terminal, the common reference terminal of the analog multiplexer ADG1419 is configured as a common reference electrode input terminal, the common working terminal of the analog multiplexer ADG1419 is configured as a common working electrode input terminal, and the multiple channel terminals of the analog multiplexer ADG1419 are configured as channel interfaces.

[0017] Preferably, the temperature sensing module includes a platinum resistance temperature sensor PT1000, a precision reference resistor, and an analog-to-digital converter ADS1115. The platinum resistance temperature sensor PT1000 is connected in series with the precision reference resistor. The platinum resistance temperature sensor PT1000 is used to connect to a reference voltage source, and the precision reference resistor is used to ground. The connection point between the platinum resistance temperature sensor PT1000 and the precision reference resistor is connected to the analog signal input terminal of the analog-to-digital converter ADS1115. The internal integrated circuit clock signal terminal and internal integrated circuit data signal terminal of the analog-to-digital converter ADS1115 are configured as an internal integrated circuit data interface.

[0018] Preferably, the bus power supply and communication module includes an IO-Link transceiver MAX14827, a DC-DC converter LT8471, and a network transformer. The transmit and receive data terminals of the IO-Link transceiver MAX14827 are configured as asynchronous serial data interfaces. The +5V and +3.3V voltage output terminals of the DC-DC converter LT8471 are configured as DC power output terminals. The power input terminal of the IO-Link transceiver MAX14827 is connected to the corresponding voltage output terminal of the DC-DC converter LT8471. The data line pair of the network transformer is connected to the communication quality detection terminal and the data input terminal of the IO-Link transceiver MAX14827. The power output terminal of the network transformer is connected to the power input terminal of the DC-DC converter LT8471.

[0019] Preferably, the three-electrode sensing patch includes a working electrode, a counter electrode, and a reference electrode, wherein the working electrode, counter electrode, and reference electrode are made of stainless steel, platinum, and silver chloride, respectively.

[0020] The present invention has the following beneficial effects:

[0021] This invention automatically monitors the water quality at the end of each pipeline, measures temperature, performs electrochemical impedance spectroscopy, analyzes weak metabolic currents, and integrates the data to assess the risk of biofilm formation in real time, and finally uploads early warning information. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a structural block diagram of the present invention.

[0024] In the diagram: 1. Main control and calculation module; 2. Electrochemical impedance spectroscopy measurement module; 3. Microcurrent measurement module; 4. Multi-channel switching module; 5. Temperature sensing module; 6. Bus power supply and communication module; 7. Three-electrode sensing patch. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0026] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0027] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0028] In the description of this invention, it should be understood that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used to facilitate the description of this invention and to simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0029] Furthermore, the terms "first," "second," and "third" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0030] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0031] A remote monitoring system for secondary water supply quality, such as Figure 1 As shown, the system includes a main control and calculation module 1, an electrochemical impedance spectroscopy (EIS) measurement module 2, a microcurrent measurement module 3, a multi-channel switching module 4, a temperature sensing module 5, a bus power supply and communication module 6, and a three-electrode sensing patch 7. The main control and calculation module 1 coordinates and controls the operating timing of all modules, executes EIS fitting and microcurrent trend analysis algorithms, and makes risk decisions based on the multi-source data fusion results. The EIS measurement module 2 applies a series of small AC excitation signals of specific frequencies to the water body and accurately measures its response to obtain complex impedance data characterizing the interface properties. The microcurrent measurement module 3 continuously monitors the working electrode. The generated nanoampere-level weak current changes are converted into quantifiable digital signals to reflect microbial metabolic activity. The multi-channel switching module 4, according to instructions from the main control and computing module 1, alternately connects multiple sensor patches distributed in different geographical locations. The temperature sensing module 5 senses and uploads the real-time fluid temperature at the monitoring points, providing temperature compensation for electrochemical data and determining the temperature conditions for microbial growth. The bus power supply and communication module 6 provides stable power and ensures that all monitoring data and alarm information are transmitted to the remote monitoring center. The three-electrode sensor patch 7 directly undergoes an electrochemical reaction with the measured water body, converting the microbial attachment and metabolic processes into quantifiable digital signals. The measured electrical signals are connected to the address control input of the multi-channel switching module 4 via the multi-channel address control output of the main control and calculation module 1. The first serial peripheral interface communication terminal of the main control and calculation module 1 is connected to the serial peripheral interface configuration terminal of the electrochemical impedance spectroscopy measurement module 2. The counter electrode excitation signal output terminal of the electrochemical impedance spectroscopy measurement module 2 is connected to the common counter electrode input terminal of the multi-channel switching module 4. The reference electrode signal acquisition terminal of the electrochemical impedance spectroscopy measurement module 2 is connected to the common reference electrode input terminal of the multi-channel switching module 4. The working electrode signal detection terminal of the microcurrent measurement module 3 is connected to the multi-channel switching module 4. The common working electrode input terminal of block 4 and the analog-to-digital conversion data output terminal of microcurrent measurement module 3 are connected to the second serial peripheral interface communication terminal of main control and computing module 1. The internal integrated circuit data interface of temperature sensing module 5 is connected to the internal integrated circuit communication terminal of main control and computing module 1. The DC power output terminal of bus power supply and communication module 6 is connected to the power input terminal of each module. The asynchronous serial data interface of bus power supply and communication module 6 is connected to the universal asynchronous transceiver communication terminal of main control and computing module 1. The multiple electrode leads of the three-electrode sensing patch 7 are respectively connected to the corresponding channel interface of multi-channel switching module 4.

[0032] The main control and computing module 1 includes a microcontroller STM32H743VIT6. The first set of general-purpose input / output ports of the microcontroller STM32H743VIT6 is configured as a multi-channel address control output terminal. The clock signal output terminal, master input / slave output data terminal, master output / slave input data terminal, and slave selection signal output terminal of the first serial peripheral interface of the microcontroller STM32H743VIT6 are configured as the first serial peripheral interface communication terminal. The clock signal output terminal, master input / slave output data terminal, master output / slave input data terminal, and slave selection signal output terminal of the second serial peripheral interface of the microcontroller STM32H743VIT6 are configured as the second serial peripheral interface communication terminal. The clock signal terminal and data signal terminal of the internal integrated circuit of the microcontroller STM32H743VIT6 are configured as the internal integrated circuit communication terminal. The transmit data terminal and receive data terminal of the universal asynchronous transceiver of the microcontroller STM32H743VIT6 are configured as the universal asynchronous transceiver communication terminal.

[0033] The electrochemical impedance spectroscopy measurement module 2 includes an electrochemical front-end chip AD5940 and an operational amplifier ADA4661-2. The serial peripheral interface clock signal input, master input-slave output data, master output-slave input data, and chip select signal input of the electrochemical front-end chip AD5940 are configured as serial peripheral interface configuration terminals. The first counter electrode signal output of the electrochemical front-end chip AD5940 is configured as the counter electrode excitation signal output terminal. The first reference electrode signal input of the electrochemical front-end chip AD5940 is configured as the reference electrode signal acquisition terminal. The first working electrode signal input of the electrochemical front-end chip AD5940 is connected to the inverting input terminal of the operational amplifier ADA4661-2 through a first resistor. The first reference electrode signal output of the electrochemical front-end chip AD5940 is connected to the non-inverting input terminal of the operational amplifier ADA4661-2 through a second resistor. The output terminal of the operational amplifier ADA4661-2 is connected back to the inverting input terminal through a feedback resistor.

[0034] The microcurrent measurement module 3 includes a precision operational amplifier LMP7721, a high-precision analog-to-digital converter ADS1115ADS125H02, and a guard ring. The inverting input of the precision operational amplifier LMP7721 is set as the working electrode signal detection terminal, and the non-inverting input of the precision operational amplifier LMP7721 is used to connect to a reference voltage source. A high-resistance feedback resistor is connected between the output terminal and the inverting input terminal of the precision operational amplifier LMP7721. The output terminal of the precision operational amplifier LMP7721 is connected to the first analog signal input terminal of the high-precision analog-to-digital converter ADS1115ADS125H02. The serial peripheral interface clock signal input terminal, data output terminal, data input terminal, and chip select signal input terminal of the high-precision analog-to-digital converter ADS1115ADS125H02 are set as analog-to-digital conversion data output terminals. The guard ring is a conductive ring on a printed circuit board surrounding the inverting input terminal of the precision operational amplifier LMP7721, and the guard ring is connected to the inverting input terminal of the precision operational amplifier LMP7721.

[0035] The multi-channel switching module 4 includes an analog multiplexer ADG1419. The address signal input terminal of the analog multiplexer ADG1419 is set as the address control input terminal, the common pair terminal of the analog multiplexer ADG1419 is set as the common pair electrode input terminal, the common reference terminal of the analog multiplexer ADG1419 is set as the common reference electrode input terminal, the common working terminal of the analog multiplexer ADG1419 is set as the common working electrode input terminal, and the multiple channel terminals of the analog multiplexer ADG1419 are set as channel interfaces.

[0036] The temperature sensing module 5 includes a platinum resistance temperature sensor PT1000, a precision reference resistor, and an analog-to-digital converter ADS1115. The platinum resistance temperature sensor PT1000 is connected in series with the precision reference resistor. The platinum resistance temperature sensor PT1000 is used to connect to a reference voltage source, and the precision reference resistor is used to ground. The connection point between the platinum resistance temperature sensor PT1000 and the precision reference resistor is connected to the analog signal input terminal of the analog-to-digital converter ADS1115. The clock signal terminal and data signal terminal of the internal integrated circuit of the analog-to-digital converter ADS1115 are set as the internal integrated circuit data interface.

[0037] The bus power supply and communication module 6 includes an IO-Link transceiver MAX14827, a DC-DC converter LT8471, and a network transformer. The transmit and receive data terminals of the IO-Link transceiver MAX14827 are configured as asynchronous serial data interfaces. The +5V and +3.3V voltage output terminals of the DC-DC converter LT8471 are configured as DC power output terminals. The power input terminal of the IO-Link transceiver MAX14827 is connected to the corresponding voltage output terminal of the DC-DC converter LT8471. The data line pair of the network transformer is connected to the communication quality detection terminal and the data input terminal of the IO-Link transceiver MAX14827. The power output terminal of the network transformer is connected to the power input terminal of the DC-DC converter LT8471.

[0038] The three-electrode sensing patch 7 includes a working electrode, a counter electrode, and a reference electrode. The working electrode, counter electrode, and reference electrode are made of stainless steel, platinum, and silver chloride, respectively.

[0039] The specific steps involved in operating this remote monitoring system for secondary water supply quality are as follows:

[0040] S1: The main control and computing module 1 controls the multi-channel switching module 4 to poll the three-electrode sensor patches 7 connected to it in a predetermined order;

[0041] More specifically, the main control and calculation module 1 sends digital control signals to the address control input terminal of the multi-channel switching module 4 to sequentially select different channels on the multi-channel switching module 4, so that the electrochemical impedance spectroscopy measurement module 2, microcurrent measurement module 3 and temperature sensing module 5 can sequentially establish electrical connections with different three-electrode sensing patches 7.

[0042] S2: For the currently selected sensor patch, the temperature of the fluid at its location is measured by the temperature sensing module 5, the electrochemical impedance spectroscopy measurement module 2 performs electrochemical impedance scanning at multiple predetermined frequencies to obtain complex impedance data, and the weak current signal flowing through the working electrode is measured by the microcurrent measurement module 3.

[0043] More specifically, the resistance value of the platinum resistance temperature sensor is read by the analog-to-digital converter in the temperature sensing module 5, and the accurate fluid temperature value is obtained according to the predetermined conversion relationship.

[0044] The main control and calculation module 1 configures the electrochemical front-end chip in the electrochemical impedance spectroscopy measurement module 2 to generate a series of sinusoidal excitation signals of predetermined frequency and amplitude to be applied to the counter electrode, and simultaneously measures the response signal between the reference electrode and the working electrode, calculates and returns a series of impedance values ​​in complex form.

[0045] The weak current signal flowing through the working electrode is converted into a voltage signal by the precision operational amplifier in the microcurrent measurement module 3, and then sampled and digitized by the high-precision analog-to-digital converter.

[0046] S3: The acquired complex impedance data is fitted with an equivalent circuit model through the main control and calculation module 1 to extract at least one characteristic parameter characterizing the interface reaction process.

[0047] More specifically, the main control and calculation module 1 uses a nonlinear least squares optimization algorithm to fit the complex impedance data obtained in step S2 with an equivalent circuit model that includes solution resistance, charge transfer resistance and constant phase angle element parameters.

[0048] Iteratively adjust the parameter values ​​in the equivalent circuit model to minimize the sum of squared errors between the impedance values ​​predicted by the model and the actual measured impedance values;

[0049] The charge transfer resistance value obtained after the fitting convergence is used as a characteristic parameter to characterize the interfacial reaction process.

[0050] S4: Perform time-domain trend analysis on the weak current signal through the main control and calculation module 1, and calculate its variation characteristics;

[0051] More specifically, the main control and calculation module 1 performs smoothing and filtering processing on the weak current signal data obtained from multiple consecutive measurements of the current channel;

[0052] Calculate the offset of the smoothed current signal relative to the initial baseline value of the channel;

[0053] Calculate the rate of change of the offset over time and use it as a characteristic of the change;

[0054] S5: By integrating fluid temperature, at least one characteristic parameter and its change characteristics through the main control and calculation module 1, a risk level signal for the current monitoring point is generated according to the predetermined risk decision rules;

[0055] More specifically, the main control and calculation module 1 first determines whether the fluid temperature is within the predetermined temperature range for rapid microbial growth;

[0056] If it is within the predetermined temperature range, then it is further determined whether the relative rate of change of the charge transfer resistance characteristic parameter exceeds the first predetermined threshold, and / or whether the rate of change of the weak current signal exceeds the second predetermined threshold.

[0057] If one or both of the above conditions are met, a warning or alarm level signal indicating an increased risk of microbial contamination will be generated.

[0058] S6: The main control and computing module 1 controls the bus power supply and communication module 6 to upload the risk level signal and related characteristic data to the remote monitoring platform;

[0059] More specifically, the main control and calculation module 1 packages the risk level signal, fluid temperature value, charge transfer resistance value, weak current value and its rate of change data into a data frame in a predetermined format;

[0060] Data frames are sent to the input / output link transceiver chip in the bus power supply and communication module 6 via a universal asynchronous transceiver.

[0061] The input / output link transceiver chip uploads data to the remote monitoring platform via the industrial bus network.

[0062] Furthermore, when the secondary water supply remote monitoring system is in operation, the STM32H743VIT6 microcontroller in the main control and computing module 1 first executes the initialization program, loading pre-configured parameters from the internal memory, including the scanning frequency range of the electrochemical impedance spectroscopy, the amplitude of the excitation signal, and the sampling time interval of each channel. Subsequently, it sends digital control signals to the address pins A0, A1, and A2 of the analog multiplexer ADG1419 in the multi-channel switching module 4 through its general-purpose input / output ports PC0, PC1, and PC2. This method enables a single measurement system to cyclically monitor up to eight isolated pipe sections of three-electrode sensing patches 7, solving the problem of spatial randomness in monitoring.

[0063] Once the multiplexer selects a specific channel, the temperature sensing module 5 starts working. The analog-to-digital converter ADS1115 sends data to the main control and computing module 1 via the I2C interface. It drives the platinum resistance temperature sensor PT1000 through a constant current source and uses the ratio measurement method to accurately measure the fluid temperature. This measurement value is not only used for environmental assessment, but also provides a temperature compensation benchmark for subsequent electrochemical measurements, effectively identifying high-temperature risk environments.

[0064] Immediately afterwards, the electrochemical impedance spectroscopy measurement module 2 is started. The main control and calculation module 1 configures the electrochemical front-end chip AD5940 through the SPI interface, so that its internal waveform generator generates multi-frequency sine wave excitation signals from 0.1Hz to 100kHz. This signal is output from the CE0 pin and applied to the common electrode of the multiplexer through the potentiostat circuit composed of the operational amplifier ADA4661-2, and finally transmitted to the counter electrode of the currently selected three-electrode patch.

[0065] Meanwhile, the SE0 pin of the electrochemical front-end chip AD5940 is connected to the reference electrode on the surface via the common reference electrode of the multiplexer to accurately monitor the potential. The response current of the working electrode is detected by the high-precision transimpedance amplifier inside the electrochemical front-end chip AD5940 and converted into a voltage signal. After 24-bit analog-to-digital conversion and digital filtering, the complex impedance data containing the real and imaginary parts is transmitted to the main control and calculation module 1 via the SPI interface. This direct in-situ measurement method completely avoids the false negative problem caused by sampling and water discharge in traditional sampling methods.

[0066] Almost simultaneously, the microcurrent measurement module 3 also operates. When the main control and calculation module 1 connects the working electrode to the inverting input of the LMP7721 precision operational amplifier via a multiplexer, the electrometer-level operational amplifier is configured as a transimpedance amplifier. Its non-inverting input is biased at a reference voltage of 0.5Vcc, enabling it to detect the nanoampere-level weak current flowing through the working electrode and convert it into a voltage signal. This signal is sampled and digitized by the ADS125H02 ultra-low noise 24-bit analog-to-digital converter and then transmitted to the main control and calculation module 1 via the second SPI interface. This high-sensitivity measurement can capture the electron transfer phenomenon generated by microbial metabolism, providing direct evidence for biofilm activity.

[0067] After obtaining the raw data, the main control and calculation module 1 executes the main processing part of the monitoring algorithm. It first performs temperature compensation on the received complex impedance data, and uses a compensation model that includes the temperature coefficient of solution resistance to correct the influence of temperature change on the measurement. Then, it runs the embedded Levenberg-Marquardt nonlinear least squares fitting algorithm to iteratively fit the impedance data with the preset R(QR) equivalent circuit model. This model includes parameters such as solution resistance, charge transfer resistance and constant phase angle elements. By minimizing the sum of squared errors between the model prediction value and the actual measurement value, the key feature parameter of charge transfer resistance is finally accurately extracted. The magnitude of this parameter directly reflects the degree to which the biofilm on the electrode surface hinders electron transfer.

[0068] Simultaneously, the microcurrent data is subjected to sliding window averaging filtering to calculate its change and rate of change relative to the initial baseline value. These time series analyses can effectively identify the growth trend of microbial metabolic activities.

[0069] During the data fusion and decision-making stage, the main control and calculation module 1 integrates temperature data, charge transfer resistance value, and microcurrent change rate, and uses a rule-based expert system to determine the risk. If the temperature is in the dangerous range of 25-42℃ and the relative change rate of charge transfer resistance exceeds the preset threshold or the microcurrent change rate shows an exponential growth characteristic, then the monitoring point is determined to be at high risk and a corresponding early warning signal is generated. This multi-parameter cross-validation mechanism greatly improves the accuracy and reliability of the alarm.

[0070] Finally, data uploading and system power supply are completed through the bus power supply and communication module 6. The IO-Link transceiver MAX14827 receives the risk level and characteristic data frames packaged by the main control and computing module 1 through the UART interface, converts them into IO-Link protocol frame format, and couples them to the DC power supply line through the network transformer. At the same time, the DC-DC converter LT8471 extracts a wide range of DC voltage from the bus and generates various operating voltages required by the system through switching regulation and linear regulation. This integrated industrial bus power supply and communication design significantly reduces wiring complexity and deployment costs.

[0071] The system provides comprehensive, in-situ, and real-time monitoring of microbial activity in all potential dead water areas of a secondary water supply system. Its measurement method, based on the principle of electrochemical interface reaction, fundamentally eliminates false negatives in sampling and solves the problem of spatial randomness.

[0072] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A remote water quality monitoring system for secondary water supply, characterized in that, The system includes a main control and calculation module (1), an electrochemical impedance spectroscopy measurement module (2), a microcurrent measurement module (3), a multi-channel switching module (4), a temperature sensing module (5), a bus power supply and communication module (6), and a three-electrode sensing patch (7). The main control and calculation module (1) coordinates and controls the operation timing of all modules and executes electrochemical impedance spectroscopy fitting and microcurrent trend analysis algorithms, and makes risk decisions based on the results of multi-source data fusion. The main control and calculation module (1) performs equivalent circuit model fitting processing on the acquired complex impedance data and extracts at least one characteristic parameter characterizing the interface reaction process. The main control and calculation module (1) performs time-domain trend analysis on the weak current signal and calculates its change characteristics. The main control and calculation module (1) integrates fluid temperature, at least one characteristic parameter and change characteristics, and generates a risk level signal for the current monitoring point according to a predetermined risk decision rule. The electrochemical impedance spectroscopy measurement module (2) applies a series of small AC excitation signals of specific frequencies to the water body and accurately measures its response to obtain complex impedance data characterizing the interface properties. The microcurrent measurement module (3) continuously monitors the changes in the nanoampere-level weak current generated on the working electrode and converts it into a quantifiable digital signal to reflect the metabolic activity of microorganisms. The multi-channel switching module (4) switches and connects multiple sensor patches distributed in different geographical locations according to the instructions of the main control module. The temperature sensing module (5) senses and uploads the real-time fluid temperature of the monitoring point to provide temperature compensation for electrochemical data and determine the temperature conditions for microbial growth. The bus power supply and communication module (6) provides stable power and ensures that all monitoring data and alarm information are transmitted to the remote monitoring center. The three-electrode sensor patch (7) directly reacts with the water body being measured to convert the microbial attachment and metabolic process into a measurable electrical signal. The multi-channel address control output terminal of the main control and calculation module (1) is connected to the address control input terminal of the multi-channel switching module (4). The first serial peripheral interface communication terminal of the main control and calculation module (1) is connected to the serial peripheral interface configuration terminal of the electrochemical impedance spectroscopy measurement module (2). The counter electrode excitation signal output terminal of the electrochemical impedance spectroscopy measurement module (2) is connected to the common counter electrode input terminal of the multi-channel switching module (4). The reference electrode signal acquisition terminal of the electrochemical impedance spectroscopy measurement module (2) is connected to the common reference electrode input terminal of the multi-channel switching module (4). The working electrode signal detection terminal of the current measurement module (3) is connected to the common working electrode input terminal of the multi-channel switching module (4). The analog-to-digital conversion data output terminal of the micro-current measurement module (3) is connected to the second serial peripheral interface communication terminal of the main control and calculation module (1). The multiple electrode leads of the three-electrode sensing patch (7) are respectively connected to the corresponding channel interfaces of the multi-channel switching module (4). The three-electrode sensing patch (7) includes a working electrode, a counter electrode, and a reference electrode. The working electrode, the counter electrode, and the reference electrode are respectively made of stainless steel, platinum, and silver chloride.

2. The remote water quality monitoring system for secondary water supply according to claim 1, characterized in that, The internal integrated circuit data interface of the temperature sensing module (5) is connected to the internal integrated circuit communication terminal of the main control and computing module (1). The DC power output terminal of the bus power supply and communication module (6) is connected to the power input terminal of each module. The asynchronous serial data interface of the bus power supply and communication module (6) is connected to the universal asynchronous transceiver communication terminal of the main control and computing module (1).

3. The remote water quality monitoring system for secondary water supply according to claim 2, characterized in that, The main control and computing module (1) includes a microcontroller STM32H743VIT6. The first group of general-purpose input / output ports of the microcontroller STM32H743VIT6 is configured as a multi-channel address control output terminal. The first serial peripheral interface clock signal output terminal, master input slave output data terminal, master output slave input data terminal and slave selection signal output terminal of the microcontroller STM32H743VIT6 are configured as a first serial peripheral interface communication terminal. The second serial peripheral interface clock signal output terminal, master input slave output data terminal, master output slave input data terminal and slave selection signal output terminal of the microcontroller STM32H743VIT6 are configured as a second serial peripheral interface communication terminal. The internal integrated circuit clock signal terminal and internal integrated circuit data signal terminal of the microcontroller STM32H743VIT6 are configured as an internal integrated circuit communication terminal. The universal asynchronous transceiver transmitter transmit data terminal and receive data terminal of the microcontroller STM32H743VIT6 are configured as universal asynchronous transceiver transmitter communication terminals.

4. The remote water quality monitoring system for secondary water supply according to claim 2, characterized in that, The electrochemical impedance spectroscopy measurement module (2) includes an electrochemical front-end chip AD5940 and an operational amplifier ADA4661-2. The serial peripheral interface clock signal input terminal, master input slave output data terminal, master output slave input data terminal and chip select signal input terminal of the electrochemical front-end chip AD5940 are configured as serial peripheral interface configuration terminals. The first counter electrode signal output terminal of the electrochemical front-end chip AD5940 is configured as the counter electrode excitation signal output terminal. The first reference electrode signal input terminal of the electrochemical front-end chip AD5940 is configured as the reference electrode signal acquisition terminal. The first working electrode signal input terminal of the electrochemical front-end chip AD5940 is connected to the inverting input terminal of the operational amplifier ADA4661-2 through a first resistor. The first reference electrode signal output terminal of the electrochemical front-end chip AD5940 is connected to the non-inverting input terminal of the operational amplifier ADA4661-2 through a second resistor. The output terminal of the operational amplifier ADA4661-2 is connected back to the inverting input terminal through a feedback resistor.

5. The remote water quality monitoring system for secondary water supply according to claim 2, characterized in that, The microcurrent measurement module (3) includes a precision operational amplifier LMP7721, a high-precision analog-to-digital converter ADS1115ADS125H02, and a guard ring. The inverting input terminal of the precision operational amplifier LMP7721 is set as the working electrode signal detection terminal. The non-inverting input terminal of the precision operational amplifier LMP7721 is used to connect to a reference voltage source. A high-resistance feedback resistor is connected between the output terminal and the inverting input terminal of the precision operational amplifier LMP7721. The output terminal of the precision operational amplifier LMP7721 is connected to the first analog signal input terminal of the high-precision analog-to-digital converter ADS1115ADS125H02. The serial peripheral interface clock signal input terminal, data output terminal, data input terminal, and chip select signal input terminal of the high-precision analog-to-digital converter ADS1115ADS125H02 are set as analog-to-digital conversion data output terminals. The guard ring is a printed circuit board conductive ring surrounding the inverting input terminal of the precision operational amplifier LMP7721. The guard ring is connected to the inverting input terminal of the precision operational amplifier LMP7721.

6. The remote water quality monitoring system for secondary water supply according to claim 2, characterized in that, The multi-channel switching module (4) includes an analog multiplexer ADG1419. The address signal input terminal of the analog multiplexer ADG1419 is set as an address control input terminal. The common pair terminal of the analog multiplexer ADG1419 is set as a common pair electrode input terminal. The common reference terminal of the analog multiplexer ADG1419 is set as a common reference electrode input terminal. The common working terminal of the analog multiplexer ADG1419 is set as a common working electrode input terminal. The multiple channel terminals of the analog multiplexer ADG1419 are set as channel interfaces.

7. The remote water quality monitoring system for secondary water supply according to claim 2, characterized in that, The temperature sensing module (5) includes a platinum resistance temperature sensor PT1000, a precision reference resistor, and an analog-to-digital converter ADS1115. The platinum resistance temperature sensor PT1000 is connected in series with the precision reference resistor. The platinum resistance temperature sensor PT1000 is used to connect to a reference voltage source. The precision reference resistor is used to ground. The connection point between the platinum resistance temperature sensor PT1000 and the precision reference resistor is connected to the analog signal input terminal of the analog-to-digital converter ADS1115. The internal integrated circuit clock signal terminal and the internal integrated circuit data signal terminal of the analog-to-digital converter ADS1115 are set as internal integrated circuit data interfaces.

8. The remote water quality monitoring system for secondary water supply according to claim 2, characterized in that, The bus power supply and communication module (6) includes an IO-Link transceiver MAX14827, a DC-DC converter LT8471, and a network transformer. The transmit and receive data terminals of the IO-Link transceiver MAX14827 are configured as asynchronous serial data interfaces. The +5V and +3.3V voltage output terminals of the DC-DC converter LT8471 are configured as DC power output terminals. The power input terminal of the IO-Link transceiver MAX14827 is connected to the corresponding voltage output terminal of the DC-DC converter LT8471. The data line pair of the network transformer is connected to the communication quality detection terminal and the data input terminal of the IO-Link transceiver MAX14827. The power output terminal of the network transformer is connected to the power input terminal of the DC-DC converter LT8471.

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