Water quality monitoring device and monitoring method thereof

Abstract

The invention discloses a water quality monitoring device and a monitoring method thereof, belongs to the technical field of water quality monitoring, and solves the problems that trace hydrogen sulfide generated by sulfate reducing bacteria in a deposited layer at the bottom of a water tank which is not cleaned for a long time in a low-oxygen environment reacts with a platinum membrane electrode of a residual chlorine sensor to generate a platinum sulfide covering layer; and the electrode reading is continuously virtually high and drifts slowly. Comprising an optical transmitting module, an optical receiving module, a spectrum separation module, a signal conditioning module, a lock-in amplification module, a spectrum feature extraction module and a hydrogen sulfide recognition engine. Residual chlorine is monitored in a non-contact mode, deep ultraviolet pulse light is emitted to penetrate through a water body, a reflection spectrum is received, second derivative spectral characteristics are extracted through multichannel signal processing, and multivariable regression compensation is executed to calculate a real residual chlorine value after hydrogen sulfide interference characteristics are recognized. Meanwhile, the drift trend is quantified based on the double-time-constant integral, graded early warning is triggered, industrial standard signals are finally output, and the problem of electrode contact pollution is avoided in the whole process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water quality monitoring, and in particular to a water quality monitoring device and a monitoring method thereof. BACKGROUND

[0002] Real-time monitoring of residual chlorine in the secondary water supply system of the community booster pump station is to continuously track the residual chlorine concentration in the secondary water supply process through online sensors and other equipment. After the secondary water supply is treated by the booster pump station, it is delivered to the user. The residual chlorine may be attenuated or contaminated due to the water tank storage, pipeline transmission and other links, and the residual chlorine can inhibit the reproduction of microorganisms, which is a key indicator to ensure water quality. Real-time monitoring can timely detect abnormal residual chlorine, quickly warn water quality risks, facilitate timely intervention, avoid microbial over-standard, and is an important means to control the safety of secondary water supply, which is directly related to the safety of residents' drinking water.

[0003] However, in the process of real-time monitoring of residual chlorine in the secondary water supply system of the community booster pump station, if the water tank is not cleaned in time for a long time, a sediment layer formed by suspended particles, microbial debris and organic matter in the water will gradually accumulate at the bottom of the water tank.

[0004] Due to slow water flow and difficulty of oxygen penetration, the inside of the sediment layer forms a low-oxygen environment suitable for the survival of sulfate-reducing bacteria such as Desulfovibrio, which causes a large number of bacteria to proliferate and continuously produce trace amounts of hydrogen sulfide through metabolic action.

[0005] Since the residual chlorine sensor mostly uses a platinum membrane electrode as the core detection component, and hydrogen sulfide is a strong reducing gas, it will undergo an irreversible chemical reaction with the platinum on the electrode surface to form a gray-black platinum sulfide solid covering layer that firmly adheres to the electrode surface and is difficult to remove.

[0006] This pollution is very significant in terms of harm. On the one hand, the electrode reading will be continuously high, even if the actual residual chlorine concentration has dropped to 0 mg / L, the sensor may still show a false value of about 0.08 mg / L; on the other hand, the reading drift process is extremely slow, only about 0.01 mg / L per week. This gradual deviation is easily ignored in routine calibration, which leads to distorted monitoring data and may mislead the judgment of the residual chlorine content in the secondary water supply, and poses a potential risk to water quality safety.

[0007] Therefore, a water quality monitoring device and a monitoring method thereof are proposed to solve or alleviate the above problems. SUMMARY

[0008] The purpose of the present application is to solve the shortcomings in the prior art and provide a water quality monitoring device and a monitoring method thereof.

[0009] In order to achieve the above purpose, the present application adopts the following technical scheme: A water quality monitoring device comprises an optical emission module, an optical receiving module, a spectrum separation module, a signal conditioning module, a lock-in amplification module, a spectrum feature extraction module, a hydrogen sulfide identification engine, a variable residual chlorine regression module, a temperature compensation module, a drift warning module, and an output interface module. An optical output end of the optical emission module is optically coupled through a water body, an optical input end of the optical receiving module receives a reflected light signal through the water body, an input end of the spectrum separation module is connected to an optical signal output end of the optical receiving module, an input end of the signal conditioning module is connected to an electrical signal output end of the optical receiving module, an input end of the lock-in amplification module is connected to an output end of the signal conditioning module, an input end of the spectrum feature extraction module is connected to an output end of the lock-in amplification module, an input end of the hydrogen sulfide identification module is connected to an output end of the spectrum feature extraction module, a first input end of the variable regression module is connected to an output end of the signal conditioning module, a second input end of the variable regression module is connected to an output end of the hydrogen sulfide identification module, an output end of the temperature compensation module is connected to a third input end of the variable regression module, an input end of the drift warning module is connected to an output end of the variable regression module, and input ends of the output interface module are respectively connected to an output end of the variable regression module and an output end of the drift warning module.

[0010] Preferably, the optical emission module comprises a first NE555 timer, a first MOS tube, four deep ultraviolet light emitting diodes, an LM334 constant current source, and a first OPA2188 operational amplifier, a positive electrode of the first NE555 timer is connected to electricity, a ground end of the first NE555 timer is grounded, a control voltage end of the first NE555 timer is grounded through a first capacitor, a threshold end and a discharge end of the first NE555 timer are short-circuited and then grounded through a first resistor, a square wave output end of the first NE555 timer is connected with a second resistor, the other end of the second resistor is connected to a gate of the first MOS tube, a source of the first MOS tube is connected to electricity, a drain of the first MOS tube is connected with anodes of the four deep ultraviolet light emitting diodes, cathodes of the four deep ultraviolet light emitting diodes are commonly connected to an output end of the LM334 constant current source, a current setting end of the LM334 constant current source is connected to an output end of the first OPA2188 operational amplifier, a reference voltage end of the LM334 constant current source is grounded through a third resistor, a non-inverting input end of the first OPA2188 operational amplifier is connected to a first voltage dividing network, the first voltage dividing network comprises a first NTC thermistor and a fourth resistor, a first end of the first NTC thermistor is connected to electricity, a second end of the first NTC thermistor is connected to ground in series with the fourth resistor, and a connection node between the first NTC thermistor and the fourth resistor is connected to the non-inverting input end of the first OPA2188 operational amplifier.

[0011] Preferably, the optical receiving module comprises 8 BPW34 photodiodes, a 45° ultraviolet reflection prism, a sapphire window, a quartz optical fiber bundle, the cathodes of the 8 BPW34 photodiodes are commonly grounded, the anodes of the 8 BPW34 photodiodes are respectively connected to the inverting input terminals of eight second OPA2188 operational amplifiers in the signal conditioning module through the fifth resistor, the sixth resistor, the seventh resistor and the eighth resistor, the anodes of the 8 BPW34 photodiodes are respectively connected to the inverting input terminals of eight second OPA2188 operational amplifiers in the signal conditioning module, the inner surface of the sapphire window is spaced two millimeters from the light entrance surface of the 45° ultraviolet reflection prism, the outer surface of the sapphire window is in contact with the water body, and the light exit surface of the 45° ultraviolet reflection prism is fixedly connected with the input end of the quartz optical fiber bundle through optical glue, and the output end of the quartz optical fiber bundle is connected with the entrance slit of the spectral separation module through an SMA905 interface. The spectral separation module comprises a 1200 line / mm diffraction grating and a bandpass filter array, the entrance slit center of the diffraction grating is coaxially arranged with the output end of the quartz optical fiber bundle, and the distance therebetween is 0.5 millimeters, and the exit light path of the diffraction grating corresponds to the arrangement of the bandpass filter array, and the light exit surface of the bandpass filter array is arranged corresponding to the photosensitive surface of the BPW34 photodiode.

[0012] Preferably, the signal conditioning module comprises eight second OPA2188 operational amplifiers and a PGA280 programmable gain amplifier, the non-inverting input terminals of the eight second OPA2188 operational amplifiers are grounded through the ninth resistor, the output terminals of the eight second OPA2188 operational amplifiers are grounded through the tenth resistor and the second capacitor in parallel, the signal input terminals of the first channel to the eighth channel of the PGA280 programmable gain amplifier are respectively connected to the output terminals of the eight second OPA2188 operational amplifiers, the analog signal output terminal of the PGA280 programmable gain amplifier is connected to the signal input terminal of the AD630 phase-sensitive detector in the lock-in amplification module, and the gain control sheet selection terminal, the serial clock terminal and the serial data input terminal of the PGA280 are connected to the general input and output port of the microcontroller in the output interface module. The lock-in amplification module comprises an AD630 phase-sensitive detector, a second NE555 timer, a double-T filter and a third OPA2188 operational amplifier, the reference input terminal of the AD630 phase-sensitive detector is connected to the square wave output terminal of the second NE555 timer through a phase shift network composed of the third capacitor and the eleventh resistor, the output terminal of the AD630 phase-sensitive detector is connected to the input terminal of the double-T filter, the output terminal of the double-T filter is connected to the inverting input terminal of the third OPA2188 operational amplifier, and the output terminal of the third OPA2188 operational amplifier is connected to the input terminal of the spectral feature extraction module.

[0013] Preferably, the spectral feature extraction module includes a fourth OPA2188 operational amplifier, a fifth OPA2188 operational amplifier, and a LF398 sample and hold. The inverting input of the fourth OPA2188 operational amplifier is connected to the output of the third OPA2188 operational amplifier in the phase-locked amplifier module through a fourth capacitor, the output of the fourth OPA2188 operational amplifier is connected to its inverting input through a twelfth resistor, the inverting input of the fifth OPA2188 operational amplifier is connected to the output of the fourth OPA2188 operational amplifier through a fifth capacitor, the output of the fifth OPA2188 operational amplifier is connected to its inverting input through a thirteenth resistor, the analog signal input of the LF398 sample and hold is connected to the output of the fifth OPA2188 operational amplifier, and a sixth capacitor is connected between the positive terminal and the negative terminal of the holding capacitor of the LF398 sample and hold.

[0014] Preferably, the hydrogen sulfide identification engine includes an AD8336 correlator, a first AD633 analog multiplier, and an LM331 voltage-frequency converter. The first signal input terminal of the AD8336 correlator is used to connect to a 255-nanometer channel signal. The second signal input terminal of the AD8336 correlator is used to connect to a 280-nanometer signal through a fourteenth resistor and a seventh capacitor. The X input terminal of the first AD633 analog multiplier is connected to the signal output terminal of the AD8336 correlator. The Y input terminal of the first AD633 analog multiplier is used to connect to a differential signal. The product output terminal of the first AD633 analog multiplier is connected to the input threshold terminal of the LM331 voltage-frequency converter. The seventh capacitor is connected between the positive terminal and the negative terminal of the timing capacitor of the LM331 voltage-frequency converter.

[0015] Preferably, the variable residual chlorine regression module includes a LOG114 logarithmic amplifier, an AD538 function generator, a first INA128 instrumentation amplifier, and an AD734 analog multiplier. The analog signal input of the LOG114 logarithmic amplifier is used to connect to a 255-nanometer channel signal, the amplified output of the LOG114 logarithmic amplifier is connected to the first input of the AD734 analog multiplier, the Y input of the AD538 function generator is used to connect to a hydrogen sulfide index signal, the square function output of the AD538 function generator is connected to the second input of the AD734 analog multiplier, the differential positive input and the differential negative input of the first INA128 instrumentation amplifier are connected across the PT1000 temperature sensor in the temperature compensation module, the amplified output of the first INA128 instrumentation amplifier is connected to the third input of the AD734 analog multiplier, and the compensation output of the AD734 analog multiplier is connected to its feedback input through a first potentiometer.

[0016] Preferably, the temperature compensation module comprises a PT1000 temperature sensor, a REF200 constant current source, a second INA128 instrument amplifier, a second AD633 analog multiplier, one end of the PT1000 temperature sensor is connected to the current output end of the REF200 constant current source, the ground end of the REF200 constant current source is grounded, the positive power supply end of the REF200 constant current source is connected to electricity, the differential positive input end of the second INA128 instrument amplifier is connected to the first end of the PT1000 temperature sensor, the differential negative input end of the second INA128 instrument amplifier is connected to the second end of the PT1000 temperature sensor, the amplification output end of the second INA128 instrument amplifier is connected to the Y input end of the second AD633 analog multiplier, the X input end of the second AD633 analog multiplier is connected with a second voltage dividing network, the second voltage dividing network comprises a second NTC thermistor and a fifteenth resistor, one end of the second NTC thermistor is connected to electricity, the other end of the second NTC thermistor is grounded in series with the fifteenth resistor, and the connection node between the second NTC thermistor and the fifteenth resistor is connected with the X input end of the second AD633 analog multiplier.

[0017] Preferably, the drift warning module comprises a sixth OP A2188 operational amplifier, a seventh OP A2188 operational amplifier, a third AD633 analog multiplier, and an LM339 voltage comparator, the inverting input end of the sixth OP A2188 operational amplifier receives an input signal through a sixteenth resistor, the output end of the sixth OP A2188 operational amplifier is connected with the inverting input end through a eighth capacitor, the inverting input end of the seventh OP A2188 operational amplifier receives an input signal through a seventeenth resistor, the output end of the seventh OP A2188 operational amplifier is connected with the inverting input end through a ninth capacitor, the X input end of the third AD633 analog multiplier is connected with the output end of the sixth OP A2188 operational amplifier, the Y input end of the third AD633 analog multiplier is connected with the output end of the seventh OP A2188 operational amplifier, the product output end of the third AD633 analog multiplier is connected with the non-inverting input end of the LM339 voltage comparator, the first inverting input end of the LM339 voltage comparator is connected to a threshold of zero point five volts, the second inverting input end of the LM339 voltage comparator is connected to a threshold of one point zero volts, and the third inverting input end of the LM339 voltage comparator is connected to a threshold of two point zero volts; The output interface module comprises an XTR115 current transmitter, a MAX485 interface chip and a microcontroller, a voltage signal input end of the XTR115 current transmitter is used for connecting a residual chlorine signal, a positive electrode end of a power supply of the XTR115 current transmitter is connected with a positive electrode end of a current loop, a current output end of the XTR115 current transmitter outputs a four to twenty milliampere signal, a data input end of the MAX485 interface chip is connected with a sending end of the microcontroller, a data output end of the MAX485 interface chip is connected with a receiving end of the microcontroller, a differential bus end of the MAX485 interface chip is connected with an RS485 bus, the RS485 bus is used for connecting with an upper computer, and the microcontroller is an STM32 series.

[0018] The application further provides a monitoring method of the water quality monitoring device, which is used for executing the water quality monitoring device. The optical emission module generates deep ultraviolet pulse light in a 255nm wave band to penetrate the water body; The optical receiving module collects original light intensity data of the reflected spectrum; The spectrum separation module separates light signals of four characteristic wavelengths of 220nm, 255nm, 280nm and 300nm; The signal conditioning module performs gain amplification on four-channel photoelectric signals; The phase-locked amplification module extracts a direct current component of the signal; The spectrum feature extraction module calculates a second derivative spectrum feature; The hydrogen sulfide recognition engine detects a hydrogen sulfide characteristic index; The variable residual chlorine regression module cooperates with the temperature compensation module to perform temperature compensation of residual chlorine value calculation; The drift early warning module quantifies a long-term drift trend; The output interface module converts an industrial standard signal output.

[0019] The application has the following beneficial effects: The application performs residual chlorine monitoring in a non-contact manner, emits deep ultraviolet pulse light to penetrate the water body and receives the reflected spectrum, extracts a second derivative spectrum feature through multi-channel signal processing, performs multivariate regression compensation calculation of a real residual chlorine value after identifying a hydrogen sulfide interference feature, quantifies a drift trend based on double time constants and triggers a hierarchical early warning, finally outputs an industrial standard signal and avoids electrode contact pollution problems throughout the whole process. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be regarded as a limitation on the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor.

[0021] Figure 1 The structural block diagram of the water quality monitoring device in the present application; Figure 2 The flow block diagram of the monitoring method of the water quality monitoring device in the present application.

[0022] In the figure, 1 is an optical emission module; 2 is an optical receiving module; 3 is a spectral separation module; 4 is a signal conditioning module; 5 is a phase-locked amplification module; 6 is a spectral feature extraction module; 7 is a hydrogen sulfide identification engine; 8 is a variable residual chlorine regression module; 9 is a temperature compensation module; 10 is a drift early warning module; 11 is an output interface module. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the following will combine the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, but not all the embodiments. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of the present application.

[0025] It should be noted that: similar numbers and letters represent similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0026] In the description of the present application, it is to be understood by those skilled in the art that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship commonly understood by those skilled in the art, or the orientation or positional relationship commonly understood by those skilled in the art, only for the convenience of describing the present application and simplifying the description, and cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0027] In addition, the terms "first", "second", "third" and the like are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0028] In the description of the present application, it is to be understood that unless otherwise specified and limited, the terms "arrangement", "installation", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0029] A water quality monitoring device, as shown in Figure 1 The optical emission module 1, the optical receiving module 2, the optical spectrum separation module 3, the signal conditioning module 4, the phase-locked amplification module 5, the optical spectrum feature extraction module 6, the hydrogen sulfide identification engine 7, the variable residual chlorine regression module 8, the temperature compensation module 9, the drift warning module 10, and the output interface module 11 are shown. The optical output end of the optical emission module 1 is optically coupled through the water body, the optical input end of the optical receiving module 2 receives the reflected light signal through the water body, the input end of the optical spectrum separation module 3 is connected to the optical signal output end of the optical receiving module 2, the input end of the signal conditioning module 4 is connected to the electrical signal output end of the optical receiving module 2, the input end of the phase-locked amplification module 5 is connected to the output end of the signal conditioning module 4, the input end of the optical spectrum feature extraction module 6 is connected to the output end of the phase-locked amplification module 5, the input end of the hydrogen sulfide identification module is connected to the output end of the optical spectrum feature extraction module 6, the first input end of the variable regression module is connected to the output end of the signal conditioning module 4, the second input end of the variable regression module is connected to the output end of the hydrogen sulfide identification module, the output end of the temperature compensation module 9 is connected to the third input end of the variable regression module, the input end of the drift warning module 10 is connected to the output end of the variable regression module, and the input end of the output interface module 11 is connected to the output end of the variable regression module and the output end of the drift warning module 10.

[0030] The optical emission module 1 comprises a first NE555 timer, a first MOS tube, four deep ultraviolet light emitting diodes, an LM334 constant current source, a first OPA2188 operational amplifier, the positive electrode of the first NE555 timer is connected to electricity, the ground of the first NE555 timer is connected to ground, the control voltage end of the first NE555 timer is connected to ground through the first capacitor, the threshold end and the discharge end of the first NE555 timer are connected after being connected to ground through the first resistor, the square wave output end of the first NE555 timer is connected with the second resistor, the other end of the second resistor is connected to the gate of the first MOS tube, the source of the first MOS tube is connected to electricity, the drain of the first MOS tube is connected with the anode of the four deep ultraviolet light emitting diodes, the cathode of the four deep ultraviolet light emitting diodes is commonly connected to the output end of the LM334 constant current source, the current setting end of the LM334 constant current source is connected to the output end of the first OPA2188 operational amplifier, the reference voltage end of the LM334 constant current source is connected to ground through the third resistor, the non-inverting input end of the first OPA2188 operational amplifier is connected to the first voltage dividing network, the first voltage dividing network comprises a first NTC thermistor and a fourth resistor, the first end of the first NTC thermistor is connected to electricity, the second end of the first NTC thermistor is connected to ground after being connected in series with the fourth resistor, and the connection node between the first NTC thermistor and the fourth resistor is connected with the non-inverting input end of the first OPA2188 operational amplifier.

[0031] The optical receiving module 2 comprises eight BPW34 photodiodes, a 45° ultraviolet reflection prism, a sapphire window and a quartz optical fiber bundle, the cathodes of the eight BPW34 photodiodes are commonly connected to ground, the anodes of the eight BPW34 photodiodes are respectively connected to electricity through the fifth resistor, the sixth resistor, the seventh resistor and the eighth resistor, the anodes of the eight BPW34 photodiodes are respectively connected to the inverting input ends of the eight second OPA2188 operational amplifiers in the signal conditioning module 4, the inner surface of the sapphire window is spaced two millimeters from the light entrance surface of the 45° ultraviolet reflection prism, the outer surface of the sapphire window is in contact with the water body, the light exit surface of the 45° ultraviolet reflection prism is fixedly connected with the input end of the quartz optical fiber bundle through optical glue, and the output end of the quartz optical fiber bundle is connected with the entrance slit of the spectral separation module 3 through an SMA905 interface. The spectral separation module 3 comprises a 1200 line / mm diffraction grating and a bandpass filter array, the center of the entrance slit of the diffraction grating is coaxially arranged with the output end of the quartz optical fiber bundle, and the distance between them is zero point five millimeters, the exit light path of the diffraction grating corresponds to the arrangement of the bandpass filter array, and the light exit surface of the bandpass filter array is arranged corresponding to the photosensitive surface of the BPW34 photodiode.

[0032] The signal conditioning module 4 comprises eight second OPAs 2188 operational amplifiers, a PGA 280 programmable gain amplifier, the non-inverting input terminals of the eight second OPAs 2188 operational amplifiers are connected to ground through a ninth resistor, the output terminals of the eight second OPAs 2188 operational amplifiers are connected to ground through a tenth resistor and a second capacitor in parallel, the signal input terminals of the first to eighth channels of the PGA 280 programmable gain amplifier are respectively connected to the output terminals of the eight second OPAs 2188 operational amplifiers, the analog signal output terminal of the PGA 280 is connected to the signal input terminal of an AD630 phase-sensitive detector in the lock-in amplification module 5, and the gain control chip select terminal, the serial clock terminal and the serial data input terminal of the PGA 280 are connected to the general input and output port of a microcontroller in the output interface module 11. The lock-in amplification module 5 comprises an AD630 phase-sensitive detector, a second NE555 timer, a double-T filter and a third OPAs 2188 operational amplifier, the reference input terminal of the AD630 phase-sensitive detector is connected to the square wave output terminal of the second NE555 timer through a phase-shifting network composed of a third capacitor and an eleventh resistor, the output terminal of the AD630 phase-sensitive detector is connected to the input terminal of the double-T filter, the output terminal of the double-T filter is connected to the inverting input terminal of the third OPAs 2188 operational amplifier, and the output terminal of the third OPAs 2188 operational amplifier is connected to the input terminal of the spectral feature extraction module 6.

[0033] The spectral feature extraction module 6 comprises a fourth OPAs 2188 operational amplifier, a fifth OPAs 2188 operational amplifier and an LF398 sample and hold, the inverting input terminal of the fourth OPAs 2188 operational amplifier is connected to the output terminal of the third OPAs 2188 operational amplifier in the lock-in amplification module 5 through a fourth capacitor, the output terminal of the fourth OPAs 2188 operational amplifier is connected to its inverting input terminal through a twelfth resistor, the inverting input terminal of the fifth OPAs 2188 operational amplifier is connected to the output terminal of the fourth OPAs 2188 operational amplifier through a fifth capacitor, the output terminal of the fifth OPAs 2188 operational amplifier is connected to its inverting input terminal through a thirteenth resistor, the analog signal input terminal of the LF398 sample and hold is connected to the output terminal of the fifth OPAs 2188 operational amplifier, and a sixth capacitor is connected between the positive terminal and the negative terminal of the holding capacitor of the LF398 sample and hold.

[0034] The hydrogen sulfide recognition engine 7 comprises an AD8336 correlator, a first AD633 analog multiplier, an LM331 voltage frequency converter, a first signal input end of the AD8336 correlator is used for connecting a 255 nanometer channel signal, a second signal input end of the AD8336 correlator is connected to a 280 nanometer signal through a fourteenth resistor and a seventh capacitor, an X input end of the first AD633 analog multiplier is connected to a signal output end of the AD8336 correlator, a Y input end of the first AD633 analog multiplier is used for connecting a differential signal, a product output end of the first AD633 analog multiplier is connected to an input threshold end of the LM331 voltage frequency converter, and a timing capacitor positive end and a timing capacitor negative end of the LM331 voltage frequency converter are connected across the seventh capacitor.

[0035] The variable residual chlorine regression module 8 comprises a LOG114 logarithmic amplifier, an AD538 function generator, a first INA128 instrument amplifier, and an AD734 analog multiplier, an analog signal input end of the LOG114 logarithmic amplifier is used for connecting a 255 nanometer channel signal, an amplification output end of the LOG114 logarithmic amplifier is connected to a first input end of the AD734 analog multiplier, a Y input end of the AD538 function generator is used for connecting a hydrogen sulfide index signal, a square function output end of the AD538 function generator is connected to a second input end of the AD734 analog multiplier, a differential positive input end and a differential negative input end of the first INA128 instrument amplifier are connected across a PT1000 temperature sensor in the temperature compensation module 9, and an amplification output end of the first INA128 instrument amplifier is connected to a third input end of the AD734 analog multiplier, and a compensation output end of the AD734 analog multiplier is connected to a feedback input end thereof through a first potentiometer.

[0036] The temperature compensation module 9 comprises a PT1000 temperature sensor, a REF200 constant current source, a second INA128 instrument amplifier, and a second AD633 analog multiplier, one end of the PT1000 temperature sensor is connected to a current output end of the REF200 constant current source, a ground end of the REF200 constant current source is grounded, a power supply positive end of the REF200 constant current source is connected to a power supply, a differential positive input end of the second INA128 instrument amplifier is connected to a first end of the PT1000 temperature sensor, a differential negative input end of the second INA128 instrument amplifier is connected to a second end of the PT1000 temperature sensor, an amplification output end of the second INA128 instrument amplifier is connected to a Y input end of the second AD633 analog multiplier, and an X input end of the second AD633 analog multiplier is connected to a second voltage dividing network, the second voltage dividing network comprises a second NTC thermistor and a fifteenth resistor, one end of the second NTC thermistor is connected to a power supply, the other end of the second NTC thermistor is connected to a ground through the fifteenth resistor in series, and a connection node between the second NTC thermistor and the fifteenth resistor is connected to the X input end of the second AD633 analog multiplier.

[0037] The drift early warning module 10 comprises a sixth OPA2188 operational amplifier, a seventh OPA2188 operational amplifier, a third AD633 analog multiplier, an LM339 voltage comparator, the inverting input end of the sixth OPA2188 operational amplifier receives an input signal through a sixteenth resistor, the output end of the sixth OPA2188 operational amplifier is connected with the inverting input end and is crossed with an eighth capacitor, the inverting input end of the seventh OPA2188 operational amplifier receives an input signal through a seventeenth resistor, the output end of the seventh OPA2188 operational amplifier is connected with the inverting input end and is crossed with a ninth capacitor, the X input end of the third AD633 analog multiplier is connected with the output end of the sixth OPA2188 operational amplifier, the Y input end of the third AD633 analog multiplier is connected with the output end of the seventh OPA2188 operational amplifier, the product output end of the third AD633 analog multiplier is connected with the non-inverting input end of the LM339 voltage comparator, the first inverting input end of the LM339 voltage comparator is connected with a threshold of 0.5 volts, the second inverting input end of the LM339 voltage comparator is connected with a threshold of 1.0 volts, and the third inverting input end of the LM339 voltage comparator is connected with a threshold of 2.0 volts; The output interface module 11 comprises an XTR115 current transmitter, a MAX485 interface chip and a microcontroller, the voltage signal input end of the XTR115 current transmitter is used for connecting a residual chlorine signal, the positive electrode end of the power supply of the XTR115 current transmitter is connected with the positive electrode end of a current loop, the current output end of the XTR115 current transmitter outputs a signal of 4-20 mA, the data input end of the MAX485 interface chip is connected with the sending end of the microcontroller, the data output end of the MAX485 interface chip is connected with the receiving end of the microcontroller, the differential bus end of the MAX485 interface chip is connected with an RS485 bus, the RS485 bus is used for connecting with an upper computer, and the microcontroller is an STM32 series.

[0038] The application further provides a monitoring method of the water quality monitoring device, as shown in the following, Figure 2 The method comprises the following steps of executing the water quality monitoring device, as shown in the following, The optical emission module 1 generates deep ultraviolet pulse light of a wavelength of 255 nm to penetrate the water body, the central wavelength of the pulse light source is 255 nm ± 5 nm, the duty cycle of the pulse working state is 50% ± 2%, and the light source modulation frequency is 1 kHz ± 10%. The optical receiving module 2 collects original light intensity data of the reflected spectrum. The spectrum separation module 3 separates light signals of four characteristic wavelengths of 220 nm, 255 nm, 280 nm and 300 nm, the light separation channel comprises four wavelength points of 220 nm, 255 nm, 280 nm and 300 nm, and the optical bandwidth of each channel is 2.5 nm. The signal conditioning module 4 performs gain amplification on the four-channel photoelectric signal; The phase-locked amplification module 5 extracts the direct current component of the signal; The spectral feature extraction module 6 calculates the second derivative spectral feature. The second derivative spectral calculation uses the square relationship of the absorbance difference between adjacent wavelength points. The absorbance value of the current wavelength point is multiplied by two, and the sum of the absorbance values of the previous and next wavelength points is subtracted. The resulting difference is divided by the square of the wavelength interval, which is fixed at five nanometers. The characteristic displacement of the 228 nanometer wavelength point is monitored. The hydrogen sulfide recognition engine 7 detects the hydrogen sulfide characteristic index. The calculation of the hydrogen sulfide characteristic index includes the operation relationship of three parameters. The product of the absorbance value at 255 nanometers and the absolute value of the absorbance change rate at 280 nanometers is divided by the absorbance value at 280 nanometers. The absorbance change rate is calculated using the time difference method. The variable residual chlorine regression module 8 cooperates with the temperature compensation module 9 to perform temperature compensation of the residual chlorine value calculation. The residual chlorine value calculation uses three weighted compensations. The first coefficient is multiplied by the natural logarithm value of the absorbance at 255 nanometers, the second coefficient is multiplied by the square value of the hydrogen sulfide characteristic index, and the third coefficient is multiplied by the difference between the temperature and 25 degrees Celsius. The first coefficient, the second coefficient, and the third coefficient are determined through system calibration. The drift warning module 10 quantifies the long-term drift trend. The fast channel integral uses an exponential decay weighting accumulation with a one-hour time constant, and the slow channel integral uses an exponential decay weighting accumulation with a twenty-four-hour time constant. The drift ratio is defined as the quotient of the fast channel integral value and the slow channel integral value. When the drift ratio is greater than one point one or the slow channel integral value is greater than zero point five, a first-level alarm is triggered. When the drift ratio is greater than one point three or the slow channel integral value is greater than one point zero, a second-level alarm is triggered. When the drift ratio is greater than two point zero or the slow channel integral value is greater than two point five, a third-level alarm is triggered. The output interface module 11 converts industrial standard signal output.

[0039] When the device is used for water quality monitoring, deep ultraviolet optical detection and multi-stage signal processing chain are used to solve the problem of electrode virtual high drift caused by hydrogen sulfide in the secondary water supply system and difficult to identify. The first NE555 timer in the optical emission module 1 generates a stable 1kHz square wave signal to drive the first MOS tube to turn on, so that the four 255nm deep ultraviolet light emitting diodes emit pulsed light with a 50% duty cycle. The light is transmitted through a quartz optical fiber bundle to a sapphire window to penetrate the water. The LM334 constant current source cooperates with the first OPA2188 operational amplifier to monitor the temperature change of the first NTC thermistor in real time and dynamically adjust the driving current, ensuring that the wavelength stability of the light source is better than ±2nm.

[0040] The reflected light is folded by a 45° UV reflecting prism and enters the spectral separation module 3. A 1200 line / mm diffraction grating disperses the spectrum to a bandpass filter array, which includes a first filter, a second filter, a third filter, and a fourth filter. The first filter has a center wavelength of 220 nm and a bandwidth of ±2.5 nm. The second filter has a center wavelength of 255 nm and a bandwidth of ±2.5 nm. The third filter has a center wavelength of 280 nm and a bandwidth of ±2.5 nm. The fourth filter has a center wavelength of 300 nm and a bandwidth of ±2.5 nm. The center wavelengths are 220 nm / 255 nm / 280 nm / 300 nm, and the bandwidth is ±2.5 nm. The separated monochromatic light is received by a BPW34 photodiode array. The anode of the photodiode is connected to a 1MΩ load resistor, which converts the photocurrent into a voltage signal, avoiding the risk of platinum sulfide pollution that may be caused by electrode contact with water.

[0041] The eight second OPAs 2188 in the signal conditioning module 4 form a transimpedance amplification circuit. Each channel has a 1MΩ feedback resistor and a 1pF compensation capacitor in parallel to ensure high-frequency noise suppression. The PGA 280 programmable gain amplifier dynamically adjusts the gain of each channel through the SPI interface of the microcontroller, compensating for the attenuation of light intensity caused by window contamination.

[0042] The phase-locked amplification module 5 uses an AD630 phase-sensitive detector. The reference input receives a square wave signal from the second NE555 timer that has been phase-shifted by a 10nF capacitor and a 100kΩ resistor. The phase-sensitive detector coherently demodulates the photoelectric signal. After filtering out 50Hz power frequency interference by a double-T filter, the DC component is output by an OPA2188 second-order low-pass filter. The double-T filter is composed of a 10mH inductor, a 20nF capacitor, and a 100kΩ resistor. The signal-to-noise ratio is improved to 120dB.

[0043] In the spectral feature extraction module 6, the inverting input of the fourth OPA2188 operational amplifier is coupled to the input signal through a 100nF capacitor, and a 1MΩ feedback resistor forms a differentiator with a time constant of 100ms. The output signal is then input to the fifth OPA2188 operational amplifier through a 47nF capacitor, and a 2.2MΩ resistor forms a second differentiator with a time constant of 103.4ms. The LF398 sample-and-hold device captures the second derivative value at the 228nm wavelength point. When trace amounts of hydrogen sulfide are produced by sulfate-reducing bacteria metabolism, the characteristic absorption peak of the water body at 228nm redshifts by 0.5-1.2nm. This displacement is amplified by more than 20 times by the differentiating circuit.

[0044] In the hydrogen sulfide recognition engine 7, the AD8336 correlator calculates the cross-correlation function of the 255nm and 280nm channel signals. The first AD633 multiplier multiplies the cross-correlation output by the 280nm absorbance change rate and divides it by the baseline absorbance to generate a characteristic index of hydrogen sulfide. If the index is greater than 0.15, it indicates that the sediment layer is contaminated with hydrogen sulfide.

[0045] Among the variable residual chlorine regression module 8, the LOG114 logarithmic amplifier converts the 255nm absorbance into a logarithmic signal, the AD538 functioner squares the characteristic index of hydrogen sulfide to strengthen the pollution weight, the temperature compensation module 9, the REF200 constant current source injects 100μA current to the PT1000 temperature sensor, the second INA128 instrument amplifier detects the resistance change and generates the temperature compensation term through the second AD633 analog multiplier, and finally the AD734 analog multiplier performs the regression operation, which eliminates the cross influence of temperature fluctuation and hydrogen sulfide interference on the residual chlorine measurement.

[0046] The drift early warning system sets a double-channel integrator, the fast channel includes the sixth OPA2188 operational amplifier + 2MΩ resistor + 1μF capacitor, which captures short-term fluctuations with a time constant of 1 hour, and the slow channel includes the seventh OPA2188 operational amplifier + 10MΩ resistor + 10μF capacitor, which establishes a long-term baseline with a time constant of 24 hours, and the third AD633 analog multiplier calculates the ratio of fast and slow integral values, when hydrogen sulfide pollution causes false high readings, the drift ratio rises from 1.0 to more than 1.2 within 48 hours.

[0047] The LM339 comparator sets three levels of thresholds, and the trigger conditions are that when the drift ratio is greater than one point one or the slow channel integral value is greater than zero point five, the first level alarm is triggered, when the drift ratio is greater than one point three or the slow channel integral value is greater than one point zero, the second level alarm is triggered, and when the drift ratio is greater than two point zero or the slow channel integral value is greater than two point five, the third level alarm is triggered.

[0048] In the output interface module 11, the XTR115 current transmitter linearly maps the 0-1.0mg / L residual chlorine value to a 4-20mA signal, and the MAX485 interface chip transmits real-time data and alarm status through the MODBUS-RTU protocol.

[0049] The device replaces the platinum membrane electrode by optical non-contact detection, identifies the hydrogen sulfide characteristic displacement by the second derivative spectrum, compensates the temperature and pollution interference by variable regression, quantifies the drift trend by double time constant integration, and can still maintain the measurement accuracy of ±0.005mg / L when the hydrogen sulfide concentration is as low as 0.01mg / L, thereby early warning the risk of electrode failure and solving the problem of hidden monitoring distortion caused by microbial pollution of the water tank sediment layer.

[0050] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A water quality monitoring device, characterized in that: It includes an optical transmitting module (1), an optical receiving module (2), a spectrum separation module (3), a signal conditioning module (4), a phase-locked amplification module (5), a spectrum feature extraction module (6), a hydrogen sulfide identification engine (7), a variable residual chlorine regression module (8), a temperature compensation module (9), a drift warning module (10), and an output interface module (11); The optical output end of the optical transmitting module (1) is optically coupled to the water body, the optical input end of the optical receiving module (2) receives the reflected light signal passing through the water body, the input end of the spectrum separation module (3) is connected to the optical signal output end of the optical receiving module (2), the input end of the signal conditioning module (4) is connected to the electrical signal output end of the optical receiving module (2), the input end of the phase-locked amplification module (5) is connected to the output end of the signal conditioning module (4), the input end of the spectrum feature extraction module (6) is connected to the output end of the phase-locked amplification module (5), the input end of the hydrogen sulfide identification module is connected to the output end of the spectrum feature extraction module (6), the first input end of the variable regression module is connected to the output end of the signal conditioning module (4), the second input end of the variable regression module is connected to the output end of the hydrogen sulfide identification module, the output end of the temperature compensation module (9) is connected to the third input end of the variable regression module, the input end of the drift warning module (10) is connected to the output end of the variable regression module, and the input end of the output interface module (11) is respectively connected to the output end of the variable regression module and the output end of the drift warning module (10).

2. A water quality monitoring device according to claim 1, characterized in that: The optical transmission module (1) comprises a first NE555 timer, a first MOS tube, four deep ultraviolet light-emitting diodes, an LM334 constant current source, and a first OPA2188 operational amplifier. The positive terminal of the power supply of the first NE555 timer is connected to electricity, the ground terminal of the first NE555 timer is grounded, the control voltage terminal of the first NE555 timer is grounded through a first capacitor, the threshold terminal and the discharge terminal of the first NE555 timer are short-circuited and then grounded through a first resistor, the square wave output terminal of the first NE555 timer is connected to a second resistor, the other end of the second resistor is connected to the gate of the first MOS tube, the source of the first MOS tube is connected to electricity, and the drain of the first MOS tube is connected to the four deep ultraviolet light-emitting diodes. The anode of the tube is connected, the cathodes of the four deep ultraviolet light-emitting diodes are commonly connected to the output end of the LM334 constant current source, the current setting end of the LM334 constant current source is connected to the output end of the first OPA2188 operational amplifier, the reference voltage end of the LM334 constant current source is grounded through a third resistor, the non-inverting input end of the first OPA2188 operational amplifier is connected to a first voltage divider network, the first voltage divider network includes a first NTC thermistor and a fourth resistor, the first end of the first NTC thermistor is connected to power, the second end of the first NTC thermistor is connected in series with the fourth resistor and then grounded, and the connection node between the first NTC thermistor and the fourth resistor is connected to the non-inverting input end of the first OPA2188 operational amplifier.

3. A water quality monitoring device according to claim 1, characterized in that: The optical receiving module (2) includes 8 BPW34 photodiodes, a 45° ultraviolet reflecting prism, a sapphire window, and a quartz fiber bundle. The cathodes of the 8 BPW34 photodiodes are commonly grounded, the anodes of the 8 BPW34 photodiodes are respectively connected to the inverting input terminals of eight second OPA2188 operational amplifiers in the signal conditioning module (4), the inner surface of the sapphire window and the light incident surface of the 45° ultraviolet reflecting prism are spaced two millimeters apart, the outer surface of the sapphire window is in contact with the water body, the light emitting surface of the 45° ultraviolet reflecting prism is fixedly connected to the input terminal of the quartz fiber bundle through optical glue, and the output terminal of the quartz fiber bundle is connected to the incident slit of the spectrum separation module (3) through an SMA905 interface. The spectrum separation module (3) includes a diffraction grating with a 1200 line / mm wavelength and a bandpass filter array. The center of the incident slit of the diffraction grating is coaxially arranged with the output end of the quartz fiber bundle, and the distance between the two is 0.5 mm. The output light path of the diffraction grating corresponds to the bandpass filter array, and the light-emitting surface of the bandpass filter array corresponds to the photosensitive surface of the BPW34 photodiode.

4. A water quality monitoring device according to claim 1, characterized in that: The signal conditioning module (4) includes eight second OPA2188 operational amplifiers and a PGA280 programmable gain amplifier. The in-phase input terminals of the eight second OPA2188 operational amplifiers are grounded through a ninth resistor. The output terminals of the eight second OPA2188 operational amplifiers are grounded through a tenth resistor and a second capacitor connected in parallel. The first channel to the eighth channel signal input terminals of the PGA280 programmable gain amplifier are respectively connected to the output terminals of the eight second OPA2188 operational amplifiers. The analog signal output terminal of the PGA280 programmable gain amplifier is connected to the signal input terminal of the AD630 phase-sensitive detector in the phase-locked amplifier module (5). The gain control chip select terminal, the serial clock terminal, and the serial data input terminal of the PGA280 are connected to the general input and output port of the microcontroller in the output interface module (11). The phase-locked amplifier module (5) includes an AD630 phase-sensitive detector, a second NE555 timer, a dual-T filter, and a third OPA2188 operational amplifier. The reference input of the AD630 phase-sensitive detector is connected to the square wave output of the second NE555 timer via a phase-shift network consisting of a third capacitor and an eleventh resistor. The output of the AD630 phase-sensitive detector is connected to the input of the dual-T filter. The output of the dual-T filter is connected to the inverting input of the third OPA2188 operational amplifier. The output of the third OPA2188 operational amplifier is connected to the input of the spectral feature extraction module (6).

5. A water quality monitoring device according to claim 1, characterized in that: The spectral feature extraction module (6) includes a fourth OPA2188 operational amplifier, a fifth OPA2188 operational amplifier, and a LF398 sample and hold device. The inverting input terminal of the fourth OPA2188 operational amplifier is connected to the output terminal of the third OPA2188 operational amplifier in the phase-locked amplifier module (5) through a fourth capacitor. The output terminal of the fourth OPA2188 operational amplifier is connected to its inverting input terminal through a twelfth resistor. The inverting input terminal of the fifth OPA2188 operational amplifier is connected to the output terminal of the fourth OPA2188 operational amplifier through a fifth capacitor. The output terminal of the fifth OPA2188 operational amplifier is connected to its inverting input terminal through a thirteenth resistor. The analog signal input terminal of the LF398 sample and hold device is connected to the output terminal of the fifth OPA2188 operational amplifier. A sixth capacitor is connected between the positive terminal and the negative terminal of the holding capacitor of the LF398 sample and hold device.

6. A water quality monitoring device according to claim 1, characterized in that: The hydrogen sulfide identification engine (7) includes an AD8336 correlator, a first AD633 analog multiplier, and an LM331 voltage-frequency converter. The first signal input end of the AD8336 correlator is used to connect to a 255-nanometer channel signal. The second signal input end of the AD8336 correlator is used to connect to a 280-nanometer signal through a fourteenth resistor and a seventh capacitor. The X input end of the first AD633 analog multiplier is connected to the signal output end of the AD8336 correlator. The Y input end of the first AD633 analog multiplier is used to connect to a differential signal. The product output end of the first AD633 analog multiplier is connected to the input threshold end of the LM331 voltage-frequency converter. The seventh capacitor is connected between the positive terminal of the timing capacitor and the negative terminal of the timing capacitor of the LM331 voltage-frequency converter.

7. A water quality monitoring device according to claim 1, characterized in that: The variable residual chlorine regression module (8) includes a LOG114 logarithmic amplifier, an AD538 function generator, a first INA128 instrumentation amplifier, and an AD734 analog multiplier. The analog signal input end of the LOG114 logarithmic amplifier is used to connect to a 255 nanometer channel signal. The amplified output end of the LOG114 logarithmic amplifier is connected to the first input end of the AD734 analog multiplier. The Y input end of the AD538 function generator is used to connect to a hydrogen sulfide index signal. The square function output end of the AD538 function generator is connected to the second input end of the AD734 analog multiplier. The differential positive input end and the differential negative input end of the first INA128 instrumentation amplifier are connected across the PT1000 temperature sensor in the temperature compensation module (9). The amplified output end of the first INA128 instrumentation amplifier is connected to the third input end of the AD734 analog multiplier. The compensation output end of the AD734 analog multiplier is connected to its feedback input end through a first potentiometer.

8. A water quality monitoring device according to claim 1, characterized in that: The temperature compensation module (9) includes a PT1000 temperature sensor, a REF200 constant current source, a second INA128 instrument amplifier, and a second AD633 analog multiplier. One end of the PT1000 temperature sensor is connected to the current output end of the REF200 constant current source, the ground end of the REF200 constant current source is grounded, the positive power supply end of the REF200 constant current source is connected to electricity, the differential positive input end of the second INA128 instrument amplifier is connected to the first end of the PT1000 temperature sensor, and the differential negative input end of the second INA128 instrument amplifier is connected to The second end of the PT1000 temperature sensor and the amplified output end of the second INA128 instrumentation amplifier are connected to the Y input end of the second AD633 analog multiplier. The X input end of the second AD633 analog multiplier is connected to a second voltage divider network. The second voltage divider network includes a second NTC thermistor and a fifteenth resistor. One end of the second NTC thermistor is connected to power, the other end of the second NTC thermistor is connected in series with the fifteenth resistor and then to ground. The connection node between the second NTC thermistor and the fifteenth resistor is connected to the X input end of the second AD633 analog multiplier.

9. A water quality monitoring device according to claim 1, characterized in that: The drift warning module (10) includes a sixth OPA2188 operational amplifier, a seventh OPA2188 operational amplifier, a third AD633 analog multiplier, and an LM339 voltage comparator. The inverting input terminal of the sixth OPA2188 operational amplifier receives an input signal through a sixteenth resistor. An eighth capacitor is connected between the output terminal of the sixth OPA2188 operational amplifier and its inverting input terminal. The inverting input terminal of the seventh OPA2188 operational amplifier receives an input signal through a seventeenth resistor. A eighth capacitor is connected between the output terminal and the inverting input terminal of the seventh OPA2188 operational amplifier. There is a ninth capacitor, the X input terminal of the third AD633 analog multiplier is connected to the output terminal of the sixth OPA2188 operational amplifier, the Y input terminal of the third AD633 analog multiplier is connected to the output terminal of the seventh OPA2188 operational amplifier, the product output terminal of the third AD633 analog multiplier is connected to the non-inverting input terminal of the LM339 voltage comparator, the first inverting input terminal of the LM339 voltage comparator is connected to the 0.5 volt threshold, the second inverting input terminal of the LM339 voltage comparator is connected to the 1.0 volt threshold, and the third inverting input terminal of the LM339 voltage comparator is connected to the 2.0 volt threshold; The output interface module (11) includes an XTR115 current transmitter, a MAX485 interface chip, and a microcontroller. The voltage signal input terminal of the XTR115 current transmitter is used to connect to the residual chlorine signal. The positive terminal of the power supply of the XTR115 current transmitter is connected to the positive terminal of the current loop. The current output terminal of the XTR115 current transmitter outputs a 4 to 20 mA signal. The data input terminal of the MAX485 interface chip is connected to the transmitting terminal of the microcontroller. The data output terminal of the MAX485 interface chip is connected to the receiving terminal of the microcontroller. The differential bus terminal of the MAX485 interface chip is connected to the RS485 bus. The RS485 bus is used to connect to the host computer. The microcontroller is an STM32 series.

10. A monitoring method for a water quality monitoring device, characterized in that: The water quality monitoring device according to any one of claims 1 to 9 comprises the following steps: The optical emission module (1) generates deep ultraviolet pulse light in the 255-nanometer band to penetrate the water body; The optical receiving module (2) collects the original light intensity data of the reflection spectrum; The spectrum separation module (3) separates optical signals of four characteristic wavelengths of 220 nanometers, 255 nanometers, 280 nanometers, and 300 nanometers; The signal conditioning module (4) performs gain amplification on the four-channel photoelectric signals; The phase-locked amplifier module (5) extracts the DC component of the signal; The spectral feature extraction module (6) calculates the second-order derivative spectral features; The hydrogen sulfide identification engine (7) detects the characteristic index of hydrogen sulfide; The variable residual chlorine regression module (8) cooperates with the temperature compensation module (9) to perform temperature-compensated residual chlorine value calculation; The drift warning module (10) quantifies the long-term drift trend; The output interface module (11) converts industrial standard signal outputs.

Images