Water quality comprehensive biotoxicity on-line monitoring system

Abstract

The invention discloses a water quality comprehensive biotoxicity on-line monitoring system. According to the system, an open type three-electrode biological electrolytic tank used in a monitoring stage is used as a culture device, a monitored water body is directly adopted to culture a microbial membrane electrode and is used for sensing biological toxic substances, and real-time water quality monitoring and toxicity judgment can be realized under an electrochemical control condition. In addition, the system is sensitive in response to toxicants, the speed is extremely high after the system acts on the toxicants, and the activity recovery speed is high.

Description

Technical Field

[0001] The present invention relates to the technical field of real-time online water quality monitoring, and particularly to an online monitoring system for comprehensive biological toxicity of water quality. Background Art

[0002] Water resources are the basic conditions for the stable maintenance of human survival and social activities. In modern production and life activities, water resources are in close contact with humans in the forms of drinking water, domestic and industrial sewage, landscape water, and other natural water bodies. In the process of using water resources, chemicals entering the water environment in various forms pose potential threats to human health to varying degrees. Due to the wide range of human production and life activities in contact with water bodies, the types of chemicals entering the water environment in the form of pollutants are extremely numerous. In addition to the conventional pollutants that have been included in national control, there are also hundreds of new pollutants such as persistent organic pollutants, endocrine disruptors, antibiotics, and microplastics widely present in various water environments. Most of these chemical pollutants have obvious health hazards to the human body, such as toxicity, endocrine disruption effects, carcinogenicity, and teratogenicity.

[0003] Analyzing and detecting toxic and harmful pollutants in various water environments is a necessary measure to understand their health hazard levels. However, for the purpose of early warning, it is necessary to develop detection technologies for in-situ and real-time online analysis of pollutants. Electrochemical sensing technology is an ideal choice to meet this condition and has been proven to be applicable in the online monitoring of chemicals such as lead ions, fluoride ions, cyanide, and sulfur-containing anions. For a wide variety of organic pollutants, it is both difficult and unnecessary to specifically distinguish their concentrations one by one during online monitoring, and it is more meaningful to directly monitor their possible biological toxicity. By immobilizing electroactive microorganisms on the surface of a basic electrode to form a bioelectrochemical sensor based on biological metabolic activity, and using the principle that toxic and harmful pollutants affect the physiological metabolism of microorganisms to generate identifiable sensing electrical signals, an online monitoring technology system specifically for the comprehensive biological toxicity of water quality can be constructed.

[0004] The present invention utilizes the natural microbial communities in various water bodies, forms an electroactive microbial membrane on the surface of a basic electrode through artificial cultivation and domestication in an electrochemical system, and develops it into a bioelectrochemical sensing system for comprehensive water quality toxicity, which is used to monitor the sudden entry of toxic pollutants into the water environment. This system is simple to start and operate, has low maintenance costs, responds quickly to toxic and harmful substances in water bodies, and has stable activity. It is suitable for water quality monitoring of drinking water sources and water supply pipe networks, operation conditions monitoring of sewage treatment plants, water quality monitoring of aquaculture systems, and water quality monitoring of other water bodies, and has broad application prospects for popularization. Summary of the Invention

[0005] In view of the above problems, the present invention provides an online monitoring system for comprehensive biological toxicity of water quality, which is used to realize real-time online monitoring of the invasion of toxic pollutants into the water environment.

[0006] To solve the above technical problems, a first aspect of the present invention provides an online monitoring system for comprehensive biological toxicity of water quality, including:

[0007] An electrochemical control system, including a potentiostat, a host computer connected to the potentiostat, and an electrode wire connected to the output end of the potentiostat;

[0008] An open three-electrode bioelectrolytic cell, connected to the electrode wire and controlled by the potentiostat. The open three-electrode bioelectrolytic cell includes a housing with two open ends. Inside the housing, there is a cylindrical working electrode, and the surface of the working electrode is covered with a layer of microbial film. A counter electrode and a reference electrode are respectively arranged on the side of the housing. The counter electrode and the reference electrode both pass through the housing and the working electrode in sequence and enter the cavity formed by the working electrode. The working electrode is connected to the electrode wire through a working electrode connection wire, and the counter electrode and the reference electrode are directly connected to the electrode wire.

[0009] In some embodiments, one end of the housing serves as the water inlet, and the other end serves as the water outlet. The water inlet is provided with a water inlet filter screen.

[0010] In some embodiments, the working electrode connection wire is made of titanium wire or stainless steel wire.

[0011] In some embodiments, the material of the working electrode is carbon felt, carbon fiber, graphite or stainless steel, the material of the counter electrode is platinum, gold, titanium, stainless steel or graphite, and the material of the reference electrode is silver / silver chloride electrode, saturated calomel electrode or mercury / mercurous sulfate electrode.

[0012] In some embodiments, an electrostatic shielding layer is provided outside the electrode wire.

[0013] A second aspect of the present invention provides a method for culturing a microbial film electrode for the above online monitoring system for comprehensive biological toxicity of water quality, including the following steps:

[0014] The water outlet of the open three-electrode bioelectrolytic cell is set downward and closed, and the liquid inside the open three-electrode bioelectrolytic cell is in a mixed state;

[0015] Collect a sufficient amount of water samples from the water body to be monitored, collect high-concentration microbial strains by centrifugation or filtration, redisperse the concentrated microbial strains in the water samples as the electrolyte, inject them into the inside of the open three-electrode bioelectrolytic cell, and supplement the electrolyte with an organic carbon source at a preset concentration.

[0016] Connect the open three - electrode bioreactor to a potentiostat through the electrode wire. Keep the water inlet open, and the working temperature is between 25 - 30 °C. The potentiostat continuously applies an anodic potential to the open three - electrode bioreactor, monitors and records the time - curve of the current output. Replace the electrolyte with fresh water samples at a preset cycle to remove suspended sludge, only retaining the microbial film deposited on the surface of the working electrode. At the same time, replenish the organic carbon source again until the output current of the electrolyte tends to be stable, and determine that the cultivation of the microbial film electrode is completed.

[0017] The third aspect of the present invention proposes a method for detecting biological poisoning, which is used for the above - mentioned online monitoring system for comprehensive biological toxicity of water quality, and includes the following steps:

[0018] Horizontally immerse and fix the open three - electrode bioreactor in the water body to be monitored. Among them, the electrode wire and its joints with each electrode are kept dry above the water surface, and the output of the potentiostat is maintained within a preset range and the current dynamics is monitored. No organic carbon source is supplemented during the process.

[0019] The upper computer real - time outputs the monitoring current generated by the biological oxidation of organic matter in the water body to be monitored, and determines the occurrence of toxic chemicals according to the time dynamics of the monitoring current.

[0020] In some embodiments, the judgment conditions for the toxic chemicals include:

[0021] Calculate the average current change rate of the monitoring current per unit time. Before the toxic chemical enters the system, it is defined as (t 0-60min , t0), and the average current change rate is denoted as ν0. After the toxic chemical enters the system (t0, t 0+n ), within this time period, the average current change rate is denoted as ν1;

[0022] When ν1 ≤ 0.5ν0, it is determined that the toxic chemical has entered the system, and t0 is taken as the moment when the toxic chemical enters the system.

[0023] The beneficial effects of the present invention are as follows: Using the open three - electrode bioreactor used in the monitoring stage as a cultivation device, directly culturing the microbial film electrode with the monitored water body, it can realize water quality monitoring and toxicity determination under electrochemical control conditions; moreover, the response rate of this system to poisons is extremely fast, and the activity recovery speed is fast after acting with poisons. It is suitable for real - time monitoring of water quality in drinking water sources, water supply pipe networks, fishery farming, sewage treatment, and natural water bodies, and has the characteristics of rapid response to poisons, stable activity, simple operation, and low maintenance cost, with broad prospects for popularization and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1Schematic diagram of the structure of the online monitoring system for comprehensive biological toxicity of water quality disclosed in Embodiment 1 of the present invention;

[0025] Figure 2a Stereo schematic diagram of the open three-electrode bioreactor disclosed in Embodiment 1 of the present invention Figure 1 ;

[0026] Figure 2b Stereo schematic diagram 2 of the open three-electrode bioreactor disclosed in Embodiment 1 of the present invention;

[0027] Figure 2c Left view of the open three-electrode bioreactor disclosed in Embodiment 1 of the present invention;

[0028] Figure 3 Schematic diagram of culturing a microbial membrane electrode using an open three-electrode bioreactor disclosed in Embodiment 2 of the present invention;

[0029] Figure 4 Schematic diagram of the relationship between current and time after adding a poison in Application Example 1;

[0030] Figure 5 Schematic diagram of the relationship between different concentrations of 2,4-dichlorophenol and current using a carbon felt as the working electrode in Application Example 1;

[0031] Figure 6 Schematic diagram of the relationship between different concentrations of 2,4-dichlorophenol and current using graphite as the working electrode in Application Example 1;

[0032] Figure 7 Schematic diagram of the relationship between different concentrations of 2,4-dichlorophenol and current using a carbon felt as the working electrode in Application Example 2;

[0033] Figure 8 Schematic diagram of the relationship between different concentrations of 2,4-dichlorophenol and current using graphite as the working electrode in Application Example 2;

[0034] Wherein: 100 - Electrochemical control system, 200 - Open three-electrode bioreactor, 101 - Potentiostat, 102 - Host computer, 103 - Electrode wire, 1 - Outer shell, 2 - Working electrode, 3 - Counter electrode, 4 - Reference electrode, 5 - Working electrode connection wire, 6 - Inlet filter screen. Detailed implementation manners

[0035] To make the objectives, technical solutions and advantages of the present invention clearer and more definite, the content of the present invention will be further described in detail below with reference to the accompanying drawings and specific implementation manners. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. Additionally, it should be noted that for the sake of description, only parts related to the present invention are shown in the accompanying drawings rather than all the content.

[0036] Example 1

[0037] This example proposes an online monitoring system for comprehensive biological toxicity of water quality, as Figure 1 shown, including:

[0038] An electrochemical control system 100, including a potentiostat 101, a host computer 102 (computer devices such as a PC) connected to the potentiostat 101, and an electrode wire 103 connected to the output end of the potentiostat 101. Optionally, an electrostatic shielding layer is provided outside the electrode wire 103.

[0039] An open three - electrode bioelectrolytic cell 200, connected to the electrode wire 103 and controlled by the potentiostat 101.

[0040] The potentiostat 101 is a device that controls the potential of the working electrode 2 in the open three - electrode bioelectrolytic cell 200 with high precision and high stability through the terminal software of the host computer 102. Specifically, the potentiostat 101 is connected to the host computer 102 through a communication line and controls the open three - electrode bioelectrolytic cell 200 through the electrode wire 103.

[0041] Such as Figure 2a 、 2bAs shown in FIGS. 2a and 2c, the open-type three-electrode bioelectrolytic cell 200 includes a housing 1 with openings at both ends. Inside the housing 1, a cylindrical working electrode 2 is provided, and the surface of the working electrode 2 is covered with a layer of microbial film. A counter electrode 3 and a reference electrode 4 are respectively arranged on the side surface of the housing 1. Among them, the counter electrode 3 and the reference electrode 4 both pass through the housing 1 and the working electrode 2 in sequence and enter the cavity formed by the working electrode 2. The working electrode 2 is connected to the electrode wire 103 through the working electrode connection wire 5, and the counter electrode 3 and the reference electrode 4 are directly connected to the electrode wire 103. Optionally, the above-mentioned housing 1 can be made of a polytetrafluoroethylene cylinder, and the working electrode 2 is a conductive carbon material, which can be selected from carbon felt, carbon fiber, graphite or stainless steel mesh, etc., and is curled into a cylindrical shape with a mesh structure to facilitate the attachment of the microbial film. Among them, the working electrode 2 is connected to the electrode wire 103 through the working electrode connection wire 5 (such as a titanium wire or a stainless steel wire), and the reference electrode 4 (such as a silver / silver chloride electrode, a saturated calomel electrode or a mercury / mercurous sulfate electrode, filled with a mixed saturated solution of silver chloride and potassium chloride, and separated from the electrolytic cell solution by a ceramic diaphragm) passes through the housing 1 and is immersed in the electrolyte solution, and the electrolyte solution is filled with a mixed saturated solution of silver chloride and potassium chloride and is separated from the electrolytic cell solution by a ceramic diaphragm; the counter electrode 3 (such as platinum, gold, titanium, stainless steel or graphite) passes through the housing and is immersed in the electrolyte solution. In addition, one end of the housing 1 serves as the water inlet, and the other end serves as the water outlet. A water inlet filter screen 6 is arranged at the water inlet to intercept large solids. The open design enables the open-type three-electrode bioelectrolytic cell 200 to continuously flush the water flow through the electrode surface when used in flowing water, so as to continuously monitor the dynamic signals of water quality. The control software of the potentiostat 101 controls the potential of the working electrode 2 relative to the reference electrode 4 to be constant, and records, outputs and analyzes the generated current-time data.

[0042] Example Two

[0043] This embodiment proposes a method for culturing a microbial film electrode, which is used for the online monitoring system of comprehensive biological toxicity of water quality described in Example One, and culturing an electroactive microbial film electrode under electrochemical conditions, that is, culturing the microbial film electrode under non-flow conditions. As Figure 3 shown, it includes the following steps:

[0044] Step 1, the water outlet of the open-type three-electrode bioelectrolytic cell 200 is set downward and closed. For example, the water outlet of the housing 1 is sealed with a polytetrafluoroethylene plug, and the liquid inside the open-type three-electrode bioelectrolytic cell 200 is in a mixed state.

[0045] Step 2: Collect a sufficient amount of water samples from the water body to be monitored (rivers, lakes or ponds, water supply pipe networks, sewage treatment structures, etc.). Collect high-concentration microbial strains through centrifugation or filtration. Redisperse the concentrated microbial strains in the water sample as the electrolyte, and inject it into the interior of the open three-electrode bioelectrolytic cell 200. Then, supplement the electrolyte with an organic carbon source at a preset concentration.

[0046] Step 3: Drive the magnetic stirrer to stir slowly to maintain the spatial uniformity of the microbial community, nutrients, and other chemical components suspended in the electrolyte, and provide mild hydrodynamic shear to the surface of the working electrode to improve the mechanical strength of the cultivated biofilm. Moreover, connect the open three-electrode bioelectrolytic cell 200 to the potentiostat 101 through the electrode wire 103, and keep the water inlet open to facilitate the supplementation of oxygen and organic carbon source. The working temperature is between 25 - 30 °C. The potentiostat 101 continuously applies an anodic potential (0 to +0.4 V relative to the reference electrode) to the electrolyte, monitor and record the time curve of the current output. Replace the electrolyte with fresh water samples at a preset cycle to remove the suspended sludge, only retain the microbial film deposited on the surface of the working electrode 2, and at the same time replenish the organic carbon source again until the current output of the electrolyte tends to be stable, and determine that the cultivation of the microbial film electrode is completed.

[0047] Example Three

[0048] This example proposes a method for detecting biological poisoning, which is used for the online monitoring system of comprehensive biological toxicity of water quality described in Example One, and includes the following steps:

[0049] Step 1: Horizontally immerse and fix the open three-electrode bioelectrolytic cell 200 in the water body to be monitored. Among them, the electrode wire 103 and its joints with each electrode are kept dry above the water surface, so that the water inlet is filled and the water can flow freely and continuously through the open three-electrode bioelectrolytic cell 200. The output of the potentiostat 101 is maintained within a preset range and the current dynamics are monitored, and no organic carbon source is supplemented during the process;

[0050] Step 2: The upper computer 102 real-time outputs the monitoring current generated by the biological oxidation of organic matter in the water body to be monitored, and determines the occurrence of toxic chemicals according to the time dynamics of the monitoring current.

[0051] Specifically, the judgment conditions for toxic chemicals include:

[0052] Step 201: Calculate the average current change rate of the monitoring current per unit time. Before the toxic chemical enters the system, it is defined as (t 0-60min , t0), and the average current change rate is denoted as ν0 (mA / minute). After the toxic chemical enters the system (during the time period from t0 to t 0+n ), the average current change rate is denoted as ν1 (mA / minute);

[0053] Step 202: When ν1 ≤ 0.5ν0, it is determined that a toxic chemical has entered the system, and t0 is taken as the moment when the toxic chemical enters the system.

[0054] Application Example 1

[0055] This application example is illustrated by an on-line comprehensive biological toxicity monitoring system for urban sewage treatment plants:

[0056] The outer shell 1 of the used open three-electrode bioreactor 200 has a volume of 300 mL. The working electrode 2 is designed in two ways: one is to use a conductive carbon felt with a length of 205 mm, a width of 60 mm, and a thickness of 4 mm as the working electrode 2, which is tightly laid around the inner wall of the outer shell 1 to fix it; the other is to use a graphite ring (inner diameter 57 mm, wall thickness 5 mm, height 20 mm) instead of the carbon felt as the working electrode 2. The potentiostat 101 uses the multi-channel potentiostat CHI1030C produced by Shanghai Chenhua Instrument Co., Ltd., and the potentials of multiple above-mentioned open three-electrode bioreactors 200 are controlled by a computer, all of which are 0 V (relative to the reference electrode 4), and the change of current is recorded. In the startup stage of the system, 2 L of a sludge-water mixed sample obtained by mixing aerobic activated sludge, anaerobic digested sludge, nitrifying and denitrifying sludge in various water treatment structures in the normal operation state of a water purification plant in Guangzhou in equal volumes is directly used to cultivate the microbial membrane electrode without centrifugation, 50 mM of sodium acetate is added as an organic carbon source, and it is slowly stirred and operated for a long time at room temperature (20 - 25 °C). It is continuously operated for four weeks, and the organic carbon source is supplemented once a week during this period. Then, the electrolyte is changed to fresh tap water containing 50 mM of sodium acetate every week to remove redundant sludge. The organic carbon source is supplemented once a week in this stage.

[0057] The on-line comprehensive biological toxicity monitoring system conducts a poison response test when the microbial membrane electrode is cultivated to the mature stage (the output current is basically stable at about 15 mA). For the open three-electrode bioreactor 200 with the carbon felt as the working electrode 2, 100 μM of cadmium chloride, 2,4-dichlorophenol, and aniline are respectively added to the electrolytic cell, and the change of current with time is recorded. According to Figure 4Data shows that since the moment t0 when the poison was added, the current generated by the control electrochemical cell not interfered by the poison still increases at a rate (ν0) of +0.035 mA / minute, while the three groups of electrochemical cells with the added poison all show current decline within a certain period of time. This proves that the open three-electrode bioelectrolytic cell 200 constructed according to this scheme successfully responds to various types of poisons. The initial response rates ν1 to cadmium ions, 2,4-dichlorophenol, and aniline are -0.103, -0.424, and -0.003 mA / minute respectively, far lower than 0.5ν0. The entire poisoning reaction period lasts for more than 8 minutes and then starts to regain activity, showing the tolerance ability of the microbial membrane electrode to poisoning by various different types of poisons. Based on this response speed and intensity, using this system in continuous monitoring of various water quality can fully achieve the purpose of quickly and effectively warning of toxic substances represented by the above pollutants.

[0058] The relationship between the response intensity of the microbial membrane electrode and the concentration of toxic chemicals can not only reflect the sensitivity of the microbial membrane electrode, but also help estimate the poison concentration in the first time, which has obvious significance for water quality management. To analyze the relationship between the current response of this system and the poison concentration, 2,4-dichlorophenol with different concentrations (1 - 400 μM) was respectively added to the electrolytic cell with the carbon felt as the working electrode 2, and the current response curve was recorded. As Figure 5 shown, the microbial membrane electrode cultivated under the experimental conditions used has a significant current response to 2,4-dichlorophenol with a concentration above 10 μM (which conforms to the common pollution concentration in actual sewage), and the response amplitude is positively correlated with the concentration of 2,4-dichlorophenol. This result shows that the designed microbial membrane electrode can technically quickly obtain its approximate concentration for the suddenly emerging poison.

[0059] To test the response of the designed microbial membrane electrode to poisons at lower concentrations, the design of the working electrode 2 was modified, and a graphite ring working electrode 2 was used to improve the detection sensitivity. Microbial membrane was cultivated on the graphite surface until a stable current was generated. 2,4-dichlorophenol with different concentrations (0.1 - 80 μM) was respectively added to the electrolytic cell, and it was confirmed that the microbial membrane electrode responds to 2,4-dichlorophenol at low concentrations (0.1 - 2 μM) ( Figure 6 ). Although compared with the previous microbial membrane electrode based on the carbon felt electrode, the overall current response amplitude of the new microbial membrane electrode becomes lower (this is related to the difference between the two electrodes and does not mean that the activity becomes worse), the current response intensity is still basically positively correlated with the concentration of 2,4-dichlorophenol. Different from this, continuously increasing the concentration of 2,4-dichlorophenol cannot produce a higher response. These results show that the microbial membrane electrode based on the graphite ring has a higher level of sensitivity and is suitable for early warning detection specifically for low-concentration poisons.

[0060] Application Example 2

[0061] This application example describes the online monitoring system for comprehensive biological toxicity of water quality established for aquaculture ponds:

[0062] The open three-electrode bioelectrolytic cell 200 used, the design of the working electrode 2, and the microbial membrane electrode culture conditions are the same as those in "Application Example 1". During the system startup phase, 4 L of a mixed water sample of fish and shrimp culture from a certain aquaculture pond near Guangzhou was collected by centrifugation and used as the microbial seed source to inoculate 4 electrolytic cells with a volume of 300 mL. The microbial membrane electrodes were cultured at a potential of 0 V (relative to the reference electrode).

[0063] When the microbial membrane electrodes were cultivated to the mature stage (the output current of the carbon felt electrode sensor was basically stable at about 45 mA, and the output current of the graphite ring electrode was stable at about 30 mA), the relationship between the response intensity of the microbial membrane electrodes and the concentration of toxic chemicals was analyzed. 2,4-Dichlorophenol with a concentration range of 0.1 - 400 μM was used as a representative poison for testing. For the bioelectrochemical sensor with the carbon felt electrode as the core (see Figure 7 ), the appearance of 2,4-dichlorophenol at a concentration of 20 μM could be clearly detected, and the fluctuation of its response current and background current could be distinguished. At higher concentrations, the amplitude of the response current was positively correlated with the concentration of 2,4-dichlorophenol. The bioelectrochemical sensor with the graphite ring electrode as the core also had a significant response to 2,4-dichlorophenol (see Figure 8 ). Its sensitivity was higher than that of the sensor with the carbon felt as the core, and 2,4-dichlorophenol with a concentration above 2 μM could be clearly detected. At the same time, in the wide concentration range of 2 - 400 μM, the linear relationship between the amplitude of the response current and the concentration of 2,4-dichlorophenol was better, so it showed more excellent quantitative ability for poisons.

[0064] The above embodiments are only for explaining the technical concept and characteristics of the present invention. The purpose is to enable ordinary technicians in the field to understand the content of the present invention and implement it accordingly, and it should not be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the essence of the content of the present invention should be covered within the protection scope of the present invention.

Claims

1. A water quality comprehensive biological toxicity online monitoring system, characterized in that: include: An electrochemical control system, comprising a potentiostat, a host computer connected to the potentiostat, and an electrode line connected to an output end of the potentiostat; An open three-electrode bioelectrolysis cell is connected to the electrode line and controlled by the constant potential instrument. The open three-electrode bioelectrolysis cell includes a shell with openings at both ends. A cylindrical working electrode is arranged inside the shell. The surface of the working electrode is covered with a layer of microbial film. A counter electrode and a reference electrode are respectively arranged on the sides of the shell, wherein the counter electrode and the reference electrode pass through the shell and the working electrode in sequence and enter the cavity formed by the working electrode. The working electrode is connected to the electrode line via a working electrode connecting line, and the counter electrode and the reference electrode are directly connected to the electrode line.

2. The water quality integrated biological toxicity online monitoring system according to claim 1, characterized in that: One end of the shell is used as a water inlet, and the other end is used as a water outlet. The water inlet is provided with a water inlet filter.

3. The water quality comprehensive biological toxicity online monitoring system according to claim 1, characterized in that: The working electrode connecting wire is a titanium wire or a stainless steel wire.

4. The water quality integrated biological toxicity online monitoring system according to claim 1, characterized in that: The working electrode is made of carbon felt, carbon fiber, graphite or stainless steel, the counter electrode is made of platinum, gold, titanium, stainless steel or graphite, and the reference electrode is made of silver / silver chloride electrode, saturated calomel electrode or mercury / mercurous sulfate electrode.

5. The water quality integrated biological toxicity online monitoring system according to claim 1, characterized in that: An electrostatic shielding layer is arranged outside the electrode wire.

6. A microbial membrane electrode culture method, used in the water quality comprehensive biological toxicity online monitoring system according to any one of claims 1 to 5, characterized in that: The following steps are involved: The water outlet of the open three-electrode bioelectrolysis cell is arranged downward and is closed, and the liquid inside the open three-electrode bioelectrolysis cell is in a mixed state; A sufficient amount of water sample is collected from the monitored water body, high-concentration microbial strains are collected by centrifugation or filtration, the concentrated microbial strains are redispersed in the water sample as an electrolyte, and injected into the interior of the open three-electrode bioelectrolysis cell, and a preset concentration of organic carbon source is added to the electrolyte; The open three-electrode bioelectrolysis cell is connected to a constant potential instrument via the electrode line, the water inlet is kept open, the working temperature is between 25-30°C, the constant potential instrument continuously applies an anode potential to the open three-electrode bioelectrolysis cell, monitors and records the time curve of the current output, and replaces the electrolyte with a fresh water sample according to a preset cycle to remove suspended sludge, retaining only the microbial film deposited on the surface of the working electrode, and at the same time re-replenishing the organic carbon source until the electrolyte output current tends to be stable, and it is determined that the microbial membrane electrode culture is completed.

7. A biological poisoning detection method, used in the water quality comprehensive biological toxicity online monitoring system according to any one of claims 1 to 5, characterized in that: The following steps are involved: The open three-electrode bioelectrolysis cell is horizontally immersed and fixed in the monitored water body, wherein the electrode wire and the joints between the electrode and each electrode are kept dry above the water surface, the output of the potentiostat is kept within a preset range and the current dynamics are monitored, and no organic carbon source is added during the process; The host computer outputs the monitoring current generated by the biological oxidation of organic matter in the monitored water body in real time, and determines the presence of toxic chemicals based on the time dynamics of the monitoring current.

8. The biological poisoning detection method according to claim 7, characterized in that: The criteria for determining toxic chemicals include: Calculate the average current change rate of the monitoring current per unit time, which is defined as (t 0-60min , t0), the average current change rate is recorded as ν0, after the toxic chemicals enter the system (t0, t 0+n ) time period, the average current change rate is recorded as ν1; when ν1≤0.5ν0, it is determined that toxic chemicals have entered the system, and t0 is taken as the moment when the toxic chemicals enter the system.

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