Water quality comprehensive toxicity biological early warning device and early warning method thereof

Abstract

The invention belongs to the technical field of microbial fuel cell water quality toxic pollutant detection. The invention provides a water quality comprehensive toxicity biological early warning device which comprises a water distribution unit and a detection unit, the water distribution unit comprises a tap water tank, a sampling tank, a clear water tank, a nutrient solution tank, a catholyte pump, a water sample pump, a nutrient solution pump, a tee joint, a mixer, an electromagnetic three-way valve, a sample reserving electromagnetic three-way valve and a sample reserving bottle; the detection unit comprises a sensor and a voltage detection and calculation unit; the sensor is a common-cathode microbial fuel cell; the common-cathode microbial fuel cell comprises a proton exchange membrane, a cathode chamber and four anode chambers, and the four anode chambers are uniformly distributed around the cathode chamber and are separated from the cathode chamber by the proton exchange membrane. The common-cathode microbial fuel cell provided by the invention is used as a water toxicity sensor, and the performance difference between individuals is smaller.

Description

Technical Field

[0001] The invention belongs to the technical field of toxic pollutant detection of water quality in microbial fuel cells. Background Art

[0002] MFC (microbial fuel cell) is a device that combines the metabolic process of microorganisms with electrochemical processes. It is a technology that directly converts chemical energy into electrical energy. It is achieved by the process of microorganisms decomposing organic matter in the anode chamber and releasing electrons and protons. These electrons flow to the cathode through an external circuit, where they react with protons and oxygen to produce water, thereby completing the closure of the entire circuit and generating current. The core is to use the electrogenic microorganisms (such as electrogenic bacteria) on the anode to oxidize and decompose organic matter to produce protons and electrons. Protons migrate to the cathode chamber through a proton exchange membrane (or cation exchange membrane), while electrons are transferred to the cathode through an external circuit, combining with electron acceptors (such as oxygen) in the cathode chamber to form a closed loop and generate current. In this process, the metabolic activities of microorganisms are directly converted into electrical energy, realizing the conversion of bioenergy and electrical energy.

[0003] The MFC biological toxicity monitor is a new environmental monitoring technology that combines the principles of microbiology and electrochemistry. In the MFC biological toxicity monitor, toxic substances can inhibit the metabolic activity of anode electrogenic microorganisms, causing changes in the output voltage or current signal of the MFC. By monitoring the changes in this electrical signal, real-time monitoring and early warning of toxic substances in water quality can be achieved.

[0004] The monitoring method based on microbial fuel cells (MFCs) is a branch of water quality biological toxicity monitoring technology. The principle of monitoring water quality is that toxic pollutants will affect the metabolic activity of electrochemically active microorganisms, thereby causing changes in the MFC output signal. By monitoring the MFC output signal, real-time monitoring of water quality toxicity can be achieved. Compared with fish, fleas, etc. as test organisms, the MFC-based monitoring method does not require additional signal transduction devices, can be self-driven, and is more suitable for continuous online analysis.

[0005] In the existing MFC-based monitoring methods, MFC mostly adopts the design of air cathode to improve the space utilization of monitoring equipment and the power generation efficiency of the battery. Compared with the aqueous cathode, the air cathode has a higher production cost and insufficient stability. Some monitoring methods also use MFC with aqueous cathode as a monitoring sensor, but the basic principle is the same as that of the air cathode: MFC is divided into a reference cell for blank water samples and a test cell for test water samples according to its function. The difference in power generation of the two cells is used to characterize the toxicity of water quality, which requires that the reference cell and the test cell maintain a high degree of consistency. Summary of the invention

[0006] In view of this, the present invention provides a water quality comprehensive toxic biological early warning device, comprising: a water distribution unit and a detection unit, wherein: the water distribution unit comprises: a tap water tank, a sampling tank, a clean water tank, a nutrient solution tank, a cathode liquid pump, a water sample pump, a nutrient solution pump, a positive three-way valve, a mixer, an electromagnetic three-way valve, a sample retention electromagnetic three-way valve and a sample retention bottle; the detection unit comprises a sensor and a voltage detection calculation unit; the sensor is a common cathode microbial fuel cell; the common cathode microbial fuel cell comprises a proton exchange membrane, a cathode chamber and four anode chambers; the four anode chambers are evenly distributed around the cathode chamber and separated from the cathode chamber by the proton exchange membrane; the anode chamber is provided with an anode electrode, an anode liquid inlet The cathode chamber is provided with a cathode electrode, a cathode liquid inlet and a cathode liquid outlet; the voltage detection unit is respectively connected with the cathode electrode and the anode electrode, and is used to detect the voltage difference between each anode chamber and the cathode chamber; the cathode liquid inlet is connected with the cathode liquid pump and the tap water tank in sequence through a liquid pipeline; the anode liquid inlet is connected with the sample retention electromagnetic three-way valve, the mixer, the positive three-way valve, the nutrient solution pump and the nutrient solution tank in sequence through a liquid pipeline; the sample retention electromagnetic three-way valve is also connected with the sample retention bottle through a liquid pipeline; the positive three-way valve is also connected with the water sample pump, the electromagnetic three-way valve and the sampling tank in sequence through a liquid pipeline; the electromagnetic three-way valve is also connected with the clean water tank through a liquid pipeline.

[0007] Furthermore, a magnetic stirring device is also provided in the common cathode microbial fuel cell.

[0008] The common cathode microbial fuel cell provided by the present invention is used as a water quality toxicity sensor. Compared with four independent double-chamber or single-chamber microbial fuel cells, the four cell structures of the common cathode microbial fuel cell have more similar microenvironments and smaller performance differences between individuals. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a schematic diagram of the comprehensive toxic biological early warning device for water quality.

[0010] Figure 2 This is a schematic diagram of the structure of a microbial fuel cell.

[0011] Figure 3 This is a schematic diagram of the structure of a microbial fuel cell.

[0012] Figure 4 This is a schematic diagram of the structure of a microbial fuel cell. DETAILED DESCRIPTION

[0013] Example

[0014] The present invention uses a common cathode microbial fuel cell as a water quality toxicity sensor to reduce the change in battery power generation caused by the cathode, thereby accurately and effectively warning of water quality toxicity. At the same time, the residence time of the water sample to be tested at the MFC anode is set to allow the water sample to fully contact the anode microorganisms, thereby more accurately warning of water quality toxicity.

[0015] The device provided by the present invention has the advantages of long service life, strong anti-interference ability, high sensitivity, wide monitoring range, simple daily management and low operating cost.

[0016] The present invention provides a water quality comprehensive toxicity biological early warning device based on a common cathode microbial fuel cell, the device comprises a water distribution unit and a detection unit, wherein:

[0017] The water distribution unit includes: a tap water tank 1, a sampling tank 2, a clean water tank 3, a nutrient solution tank 4, a cathode liquid pump 5, a water sample pump 6, a nutrient solution pump 7, a positive three-way valve 8, a mixer 9, an electromagnetic three-way valve 10, a sample retention electromagnetic three-way valve 11, and a sample retention bottle 15.

[0018] The detection unit includes a sensor and a voltage detection unit, and the sensor is a common cathode microbial fuel cell 12 .

[0019] The common cathode microbial fuel cell suitable for water quality biological toxicity warning includes a cathode chamber and four anode chambers. A magnetic stirrer is placed inside the cathode chamber. The four anode chambers are evenly distributed around the cathode chamber and separated from the cathode chamber by a proton exchange membrane. That is, the proton exchange membrane is used as a boundary to separate four anode chambers and one cathode chamber. The anode chambers are independent of each other and can be used as four working channels. A magnetic stirring device 34 is placed at the bottom of the cathode chamber of the common cathode microbial fuel cell, which is used to evenly distribute the dissolved oxygen in the cathode liquid by magnetic stirring. A cathode electrode is arranged in the cathode chamber. An anode electrode is arranged in the anode chamber.

[0020] The voltage detection unit is connected to the cathode electrode and the anode electrode respectively, and is used to detect the voltage difference between each anode chamber and the cathode chamber.

[0021] The cathode liquid in the cathode chamber is tap water, and the anode liquid in the anode chamber is 0.2 g / L sodium acetate.

[0022] The common cathode microbial fuel cell 12 is composed of a cathode chamber housing 32, an anode chamber housing 25, an upper cover plate 27, a first waterproof gasket 22, a second waterproof gasket 24, a third waterproof gasket 35, a proton exchange membrane 23, an anode electrode 33, a cathode electrode 31, and a magnetic stirring device 34.

[0023] The upper cover plate 27 is provided with a cathode liquid inlet 29 and a cathode liquid outlet 30 ; the cathode liquid inlet 29 is connected to the cathode liquid pump 5 and the tap water tank 1 in sequence through a liquid pipeline.

[0024] An anode liquid inlet 21 and an anode liquid outlet 28 are provided on the anode chamber shell 25; the anode liquid inlet 21 is connected in sequence with the sample retaining electromagnetic three-way valve 11, the mixer 9, the positive three-way valve 8, the nutrient solution pump 7 and the nutrient solution tank 4 through a liquid pipeline; the sample retaining electromagnetic three-way valve 11 is also connected with the sample retaining bottle 15 through a liquid pipeline; the positive three-way valve 8 is also connected in sequence with the water sample pump 6, the electromagnetic three-way valve 10 and the sampling tank 2 through a liquid pipeline; the electromagnetic three-way valve 10 is also connected with the clean water tank 3 through a liquid pipeline.

[0025] The 4 channels of the detection unit rotate between the detection and standby working states, that is, when any one channel is in the detection state, the other three channels are in the standby state:

[0026] A. When a channel is used as a detection channel:

[0027] The ac ends of the electromagnetic three-way valve 10 are connected, and the water sample to be tested is driven by the water sample pump 6 to enter the mixer 9 from the sampling tank 2 according to the set flow rate; at the same time, the nutrient solution is driven by the nutrient solution pump 7 to enter the mixer 9 from the nutrient solution tank 4 according to the set flow rate, and finally the water sample to be tested and the nutrient solution are mixed in the mixer 9; and enter a certain anode chamber according to the set flow rate; the other three anode chambers are in a standby state;

[0028] Detect the voltage value of the battery. When the voltage value rises to a preset value, the mixed liquid stops entering the anode chamber, and the mixed liquid in the anode chamber is in a static state;

[0029] Detect the voltage value of the battery. When the voltage value drops to a preset value, a new mixed liquid starts to enter the anode chamber. After the old mixed liquid is completely replaced, the voltage value of the battery is detected next time. When the voltage value rises to a preset value, the mixed liquid stops entering the anode chamber, and the mixed liquid in the anode chamber is in a static state. This reciprocating process is used to achieve multi-cycle voltage detection.

[0030] B. When other channels are used as standby channels:

[0031] The bc ends of the electromagnetic three-way valve 10 are connected, and the clean water is driven by the water sample pump 6 from the clean water tank 3 to enter the mixer 9 according to the set flow rate; at the same time, the nutrient solution is driven by the nutrient solution pump 7 from the nutrient solution tank 4 to enter the mixer 9 according to the set flow rate. Finally, the clean water and the nutrient solution are mixed in the mixer 9; and then enter other standby anode chambers according to the set flow rate.

[0032] Since the set flow rate of the water sample is consistent with the set flow rate of the clean water, and the set flow rate of the nutrient solution is consistent, this ensures that the microbial environment of the standby anode chamber and the detection anode chamber is consistent.

[0033] The water quality biological toxicity early warning method based on a common cathode microbial fuel cell comprises the following steps:

[0034] First, calibration

[0035] First, collect the voltage signal of period T;

[0036] Next, calculate the voltage-time integral of period T

[0037] Finally, calculate the voltage-time integral variation coefficient x of the three adjacent cycles:

[0038]

[0039] If |x|>5%, restart the calibration procedure;

[0040] If |x|≤5%, enter the detection procedure.

[0041] Second, monitoring

[0042] First, collect the voltage signal of period T;

[0043] Secondly, calculate the change D of the voltage signal integral between periods T = m and T = m-3:

[0044]

[0045] If |D| < 10%, continue the detection procedure;

[0046] If |D|≥10%, an alarm will be issued and the sample will be retained.

[0047] Third, call the police and keep samples

[0048] The ab ends of the electromagnetic three-way valve 11 are connected, and the mixed liquid containing the water sample enters the sample bottle 15.

[0049] Fourth, the detection channel is switched to the next channel, and the next anode chamber is used for detection to realize alarm monitoring.

[0050] Using a common cathode microbial fuel cell as a water quality toxicity sensor: Compared with four independent dual-chamber or single-chamber microbial fuel cells, the four cell structures of the common cathode microbial fuel cell have a more similar microenvironment and smaller performance differences between individuals.

[0051] The device uses microbial fuel cells as water quality biotoxicity sensors. Each cell can serve as four working channels. Each channel can achieve two states, detection and standby, by switching pumps and valves, and retain water samples that trigger warnings.

[0052] When the detection channel warns of biological toxicity, a sample retention function is set. After a biological toxicity warning, toxic water samples are retained by switching the flow path, providing a basis for the accuracy of the warning and subsequent improvements.

[0053] After the sample retention step is completed, the bc ends of the electromagnetic three-way valve 10 of the detection channel are connected, and clean water flushes the detection anode chamber through the ac end of the electromagnetic valve 11 and switches to a standby state.

[0054] In this scheme, the cathode liquid is tap water, and the nutrient solution formula of the anode liquid is 0.2 g / L sodium acetate.

[0055] The flow rate and opening and closing of each pump valve can be controlled by program. Periodic detection is adopted, and each detection cycle is divided into a sampling stage and a reaction stage. The integral difference of the electrical signal time Tn and Tn+3 in a complete detection cycle is used as a representation of the biological toxicity of water quality.

[0056] The device of the present invention has the following advantages:

[0057] 1) No mixing unit: In the existing common cathode battery solution, the anode is evenly distributed around the cathode. If there is no mixing device when used as a sensor, it is impossible to ensure that the concentration of electron acceptors near the exchange membrane is consistent.

[0058] 2) Insufficient early warning accuracy: There are many factors that affect the power output of MFC, and the power difference between cells cannot be completely attributed to water toxicity, especially when the reference cell and the test cell are independent of each other.

[0059] 3) The early warning results cannot be verified: without sample retention facilities, the accuracy of the early warning results cannot be verified.

[0060] 4) The common cathode microbial fuel cell comprises 2, 3 or more anode chambers;

[0061] 5) The difference in electrical signals between two time points and the integral difference in electrical signal time within two time periods can both be used as indicators of biological toxicity;

[0062] 6) The difference in electrical signals between the detection channel and the standby channel can also be used as a representation of biological toxicity;

[0063] 7) The electrical signal can be the voltage or current between the positive and negative electrodes of the battery.

Claims

1. A water quality comprehensive toxic biological early warning device, characterized in that: include: Water distribution unit and detection unit, where: The water distribution unit comprises: a tap water tank, a sampling tank, a clean water tank, a nutrient solution tank, a cathode liquid pump, a water sample pump, a nutrient solution pump, a positive three-way valve, a mixer, an electromagnetic three-way valve, a sample retention electromagnetic three-way valve and a sample retention bottle; The detection unit includes a sensor and a voltage detection calculation unit; the sensor is a common cathode microbial fuel cell; The common cathode microbial fuel cell comprises a proton exchange membrane, a cathode chamber and four anode chambers; the four anode chambers are evenly distributed around the cathode chamber and separated from the cathode chamber by the proton exchange membrane; the anode chamber is provided with an anode electrode, an anode liquid inlet and an anode liquid outlet; the cathode chamber is provided with a cathode electrode, a cathode liquid inlet and a cathode liquid outlet; The voltage detection unit is connected to the cathode electrode and the anode electrode respectively, and is used to detect the voltage difference between each anode chamber and cathode chamber; The cathode liquid inlet is connected to the cathode liquid pump and the tap water tank in sequence through a liquid pipeline; The anode liquid inlet is connected with the sample retention electromagnetic three-way valve, the mixer, the positive three-way valve, the nutrient solution pump and the nutrient solution tank in sequence through the liquid pipeline; The sample retention electromagnetic three-way valve is also connected to the sample retention bottle through a liquid pipeline; The positive three-way valve is also connected to the water sample pump, the electromagnetic three-way valve and the sampling tank in sequence through the liquid pipeline; The electromagnetic three-way valve is also connected to the clean water tank through a liquid pipeline.

2. The water quality comprehensive toxicity biological early warning device according to claim 1 is characterized in that: The common cathode microbial fuel cell is also provided with a magnetic stirring device.

3. The early warning method of the water quality comprehensive toxic biological early warning device according to any one of claims 1 or 2, characterized in that: The steps include: First, calibration First, collect the voltage signal of period T; Next, calculate the voltage-time integral of period T Finally, calculate the voltage-time integral variation coefficient x of the three adjacent cycles: If |x|>5%, restart the calibration procedure; If |x|≤5%, enter the detection procedure; Second, monitoring First, collect the voltage signal of period T; Secondly, calculate the change D of the voltage signal integral between periods T = m and T = m-3: If |D| < 10%, continue the detection procedure; If |D|≥10%, an alarm will be sounded and samples will be retained; Third, call the police and keep samples The ab ends of the electromagnetic three-way valve are connected, and the mixed liquid containing the water sample enters the sample bottle.

4. The early warning method of the water quality comprehensive toxic biological early warning device according to claim 3, characterized in that After the alarm is triggered and the sample is retained, the following steps are also included: The detection channel switches to the next channel, and the next anode chamber is used for detection to realize alarm monitoring; At the same time, the bc end of the electromagnetic three-way valve of the detection channel is connected, and clean water flushes the detection anode chamber through the ac end of the electromagnetic valve and switches to a standby state.

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