CN203768095U - Device for in-situ remediation of polluted groundwater by using microbial electrolysis cell process - Google Patents

Abstract

The utility model discloses a device for in-situ remediation of polluted groundwater by using a microbial electrolysis cell process. The device comprises a sealed anode chamber and a sealed cathode chamber arranged in the polluted groundwater, wherein small holes are formed in the chamber wall of each of the anode chamber and the cathode chamber; an anode electrode and a cathode electrode are respectively placed in the anode chamber and the cathode chamber, and are respectively connected with a high potential end and a low potential end of a voltage-stabilized power supply; electricity production microorganisms are adhered to the surface of the anode electrode. The device disclosed by the utility model can be used for removing reducing organic pollutants in sewage while obtaining hydrogen energy. In addition, the device can be used for removing some pollutants such as Pb<2+>, Ni<2+>, chlorohydrocarbon and pentavalent uranium with relatively low reduction potentials.

Description

Device for in-situ remediation of contaminated groundwater using microbial electrolysis cell technology

technical field

The utility model belongs to the technical field of groundwater treatment, in particular to a device for in-situ repairing of polluted groundwater using microbial electrolytic cell technology and simultaneously obtaining hydrogen energy or recovering metals.

Background technique

As a precious fresh water resource for human beings, groundwater has been polluted to varying degrees with the continuous development of industrialization in modern society. Since the 1960s, groundwater pollution has gradually increased, so groundwater restoration technology has also been developed. Groundwater pollution remediation technologies include ex-situ remediation, in-situ remediation and monitoring natural attenuation technologies. Ex-situ remediation technology is a technology that pumps contaminated groundwater to the surface for treatment. This technology has a large processing capacity and high processing efficiency in a short period of time, but long-term application generally has phenomena such as tailing and rebound, which ultimately reduces processing efficiency and increases processing costs. Monitoring natural attenuation technology is a restoration technology that fully relies on natural purification capabilities, and requires a long restoration time. In addition, the types of pollutants in groundwater are increasing day by day. In addition to organic matter, they also include heavy metals, inorganic salts and radioactive elements. Therefore, the in-situ remediation technology for groundwater pollution is characterized by thorough restoration, many types of pollutants, and relatively short time. Advantages such as relatively low cost have emerged in the field of groundwater pollution remediation. Among them, the in-situ bioremediation technology refers to the removal of groundwater through the action of organisms (especially microorganisms) in the original place without carrying or transporting the contaminated objects under the condition of basically not destroying the natural environment of the soil and groundwater. method of contamination. The in-situ bioremediation technology has significant advantages such as fast speed, less interference, high efficiency, low cost and mild reaction conditions, and has become an important technology for in-situ remediation of groundwater pollution. However, in situ bioremediation technology also has some limitations. For example, the key to in-situ remediation of contaminated groundwater by microorganisms is to maintain the high activity of corresponding microorganisms, so that the pollutants in groundwater can be efficiently removed.

In recent years, microbial fuel cell (Microbial Fuel Cell, MFC) technology is becoming one of the new concept wastewater treatment technologies, which can obtain electricity while treating wastewater. MFC technology has been used to remediate contaminated groundwater in situ (CN 102659237 A). The method utilizes the microorganisms in the anode chamber to catabolize and remove the reductive pollution in the groundwater, and uses the cathode chamber to reduce and remove the oxidative pollutants in the groundwater, and simultaneously obtains electric energy. In addition, this method places the cathode electrode in the cathode chamber open to the atmosphere to overcome the implementation difficulty of adding electron acceptors to groundwater, but in this method the electron acceptor (oxygen in the air) enters the cathode by diffusion The supply speed of the electron acceptor is slow, and the solubility of the electron acceptor in water is low. At the same time, biofilm is easy to form on the surface of the cathode electrode, which reduces the efficiency of the cathode reaction and the removal efficiency of pollutants. In addition, this method cannot remove pollutants such as Pb ²⁺ , Ni ²⁺ , chlorinated hydrocarbons and pentavalent uranium (U(V)) with low reduction potential.

Microbial Electrolysis Cell (MEC) is a new technology developed rapidly in recent years that combines sewage treatment and energy generation. It can obtain different forms of energy while biologically treating sewage, and is used as a new process for sewage treatment. , has aroused widespread attention at home and abroad. There is no need to provide electron acceptors (O ₂ ) in MEC, which can avoid the problem that MFC needs to add electron acceptors to groundwater for in-situ remediation of groundwater pollutants. In addition, some pollutants such as Pb ²⁺ , Ni ²⁺ , chlorinated hydrocarbons and U(V) with low reduction potential that cannot be removed in MFC can be removed in the cathode of MEC.

Contents of the invention

The utility model provides a device for in-situ repairing of polluted groundwater using microbial electrolytic cell technology, so as to avoid the traditional in-situ repairing of polluted groundwater and the use of microbial fuel cell technology for in-situ repairing of polluted groundwater requiring adding electron acceptors to the groundwater At the same time, it can remove some pollutants such as Pb ²⁺ , Ni ²⁺ , chlorinated hydrocarbons and U(V) with low reduction potential that cannot be removed in the method of in-situ remediation of contaminated groundwater using microbial fuel cell technology.

In order to solve the above problems, the utility model adopts the following technical solutions:

The utility model utilizes microbial electrolytic cell technology to restore polluted groundwater in situ, and is characterized in that a sealed anode chamber and a sealed cathode chamber are arranged in the polluted groundwater, and the chamber walls of the anode chamber and the cathode chamber are all provided with small holes ; Place the anode electrode and the cathode electrode in the anode chamber and the cathode chamber respectively; connect the high potential end and the low potential end of the regulated power supply to the anode electrode and the cathode electrode respectively; make the polluted groundwater flow through the small holes in the walls of the anode chamber and the cathode chamber Through the anode electrode and cathode electrode in the anode chamber and cathode chamber, the reducing organic pollutants in the sewage are degraded and removed as the metabolic substrate of the electrogenic microorganisms attached to the surface of the anode electrode. The H ⁺ and electrons generated by the electro-microbial metabolism of organic pollutants migrate to the cathode chamber and combine on the surface of the cathode electrode to produce H ₂ . In addition, some oxidative pollutants with low redox potential in groundwater are reduced and removed on the surface of the cathode electrode.

The anode electrode material is carbon cloth, graphite felt, mesh glassy carbon, graphite or carbon fiber brush.

The cathode electrode material is Pt modified carbon cloth, graphite felt, graphite or carbon fiber brush, or lead and copper.

The enrichment of the electricity-producing microorganisms on the surface of the anode electrode is by injecting the anaerobic activated sludge and the oxygen-removing culture medium mixture into the built anode chamber, and the current generated by the microbial electrolytic cell through a period of operation is maximum and stable, Electrode-producing microorganisms are fully attached to the surface of the anode electrode.

The potential of the cathode electrode is controlled to be -0.5V~-2.0V, and the DC output voltage of the stabilized power supply is -2.0V~2.0V.

The pollutants that can be repaired in situ by the device of the utility model include reducing pollutants such as phenol and/or benzene in the anode chamber, and oxidative pollutants such as nitrobenzenes that have a lower redox potential in the cathode chamber Compound pollution and/or chlorinated hydrocarbon pollution and/or U(V) pollution and/or Pb ²⁺ pollution and/or Ni ²⁺ pollution and/or low concentration Cu ²⁺ pollution.

For remediation of groundwater polluted by reducing pollutants phenol and/or benzene, the contaminated groundwater first flows through the anode chamber; for remediation of oxidative pollutants nitrobenzene compounds and/or chlorinated hydrocarbons and/or U(V) and /or Pb ²⁺ and/or Ni ²⁺ and/or low-concentration Cu ²⁺ polluted groundwater, make the polluted groundwater flow through the cathode chamber first; for the groundwater polluted by reducing pollutants and oxidizing pollutants simultaneously, the The anode chamber and the cathode chamber are arranged on the same section perpendicular to the flow direction of the polluted groundwater, and the polluted groundwater first flows through the cathode chamber, and then flows through the anode chamber.

Description of drawings

Fig. 1 is a schematic diagram of the structure of the anode of the microbial electrolytic cell in Example 1 of the present invention for removing reducing pollutants.

Fig. 2 is the structural representation of removing CHCl ₃ oxidative pollutants with a lower redox potential by the cathode of the microbial electrolytic cell in Example 2 of the utility model.

Detailed ways

The utility model will be described in further detail below through specific embodiments in conjunction with the accompanying drawings.

Example 1:

Fig. 1 is a schematic diagram of the structure of the anode of the microbial electrolytic cell in Example 1 of the present invention for removing reducing pollutants. In this embodiment, the microbial electrolytic cell technology is used to restore the groundwater polluted by phenol in situ, and the specific operations are carried out in the following order and steps:

(1) In-situ construction of microbial electrolysis cells under the ground in contaminated groundwater areas

Firstly, two cylindrical holes with a certain distance are drilled on the ground of the polluted groundwater area, and two polyvinyl chloride pipes with sealed bottoms and perforated pipe walls are respectively put into the cylindrical holes to form the anode chamber 1 and the cathode Chamber 6; put the carbon fiber brush anode electrode 2 into the anode chamber 1 formed by the polyvinyl chloride tube, and the anode electrode 2 is connected to the high potential of the stabilized power supply 5 through the hole on the sealing cover 3; the carbon fiber brush Cathode electrode 7 is put into the cathode chamber 6 that polyvinyl chloride tube constitutes, and cathode electrode 7 is connected with the low potential of stabilized voltage power supply 5 through the hole on sealing cover 8; The sample tube 10 is provided with a gas collection tube 11 at the upper end of the cathode chamber 6 .

(2) Enrichment of electrogenic microorganisms on the surface of the anode electrode

The anaerobic activated sludge from the sewage treatment plant is used as the inoculum, the artificially prepared simulated wastewater is used as the culture medium, and the pure nitrogen is inoculated into the microbial electrolysis cell through the sampling tube 10 at a ratio of 2:9 (v/v) after deoxygenation. The anode compartment 1 is enriched with anode electrogenic microorganisms. The microbial electrolysis cell is operated in batches, and the mixture of inoculum and medium is added according to the above ratio after each experiment. The voltage of the stabilized power supply is fixed at -0.9V, and the current data of the microbial electrolytic cell is regularly sampled. After the current of the microbial electrolytic cell is maximum and stable, it is considered that the surface of the anode electrode 1 is fully adhered to the electrogenic microorganisms.

Table 1 Composition and content of simulated artificial wastewater base fluid

Table 2 Composition and content of trace element solution

(3) In-situ remediation of phenol-contaminated groundwater

When the surface of the anode electrode 2 is fully enriched with electricity-producing microorganisms, the microbial electrolytic cell can be used for in-situ remediation of phenol-contaminated groundwater. Let the phenol-contaminated groundwater flow through the anode chamber 1 and cathode chamber 6 of the microbial electrolysis cell in sequence, while the voltage of the stabilized power supply 5 is fixed at -0.9 V. The electrogenic microorganisms attached to the surface of the anode electrode 2 metabolize the pollutant phenol in the groundwater to produce CO ₂ , H ⁺ and electrons, thereby removing the pollutants, and the generated H ⁺ and electrons migrate to the cathode chamber 6, where the H ⁺ and electrons are assisted by electricity. The surface of the cathode electrode 7 combines to generate H ₂ , and the specific chemical reaction equation is as follows:

Anode electrode

cathode electrode

And the produced H ₂ is collected through the gas collection pipe 11.

Example 2:

Fig. 2 is a structural schematic diagram of removing chloroform pollutants with low redox potential by the cathode of the microbial electrolytic cell in Example 2 of the present invention. The present embodiment utilizes microbial electrolytic cell technology to in situ remediate groundwater polluted by chloroform, and specifically operates in the following order and steps:

(1) In-situ construction of microbial electrolysis cells under the ground in contaminated groundwater areas

Firstly, two cylindrical holes with a certain distance are drilled on the ground of the polluted groundwater area, and two polyvinyl chloride pipes with sealed bottoms and perforated pipe walls are respectively put into the cylindrical holes to form the anode chamber 1 and the cathode Chamber 6; put the carbon fiber brush anode electrode 2 into the anode chamber 1 formed by the polyvinyl chloride tube, the anode electrode 2 is connected to the high potential of the stabilized voltage power supply 5 through the hole on the sealing cover 3; the copper cathode The electrode 7 is put into the cathode chamber 6 formed by the polyvinyl chloride tube, and the cathode electrode 7 is connected to the low potential of the stabilized power supply 5 through the hole on the sealing cover 8 and the lead wire 9; The tube 10 is designed with a gas collection tube 11 at the upper end of the cathode chamber 6 .

(2) Enrichment of electrogenic microorganisms on the surface of the anode electrode

The enrichment of electrogenic microorganisms on the surface of the anode electrode is the same as the enrichment of electrogenic microorganisms on the surface of the anode electrode in Example 1.

(3) In-situ remediation of chloroform-contaminated groundwater

After the surface of the anode electrode 2 is fully enriched with electricity-producing microorganisms, the microbial electrolytic cell can be used for in-situ remediation of chloroform-contaminated groundwater. Artificial simulated waste water is continuously or intermittently added into the anode chamber 1 through the sampling tube 10 to provide electron donors. Let the chloroform-contaminated groundwater flow through the cathode chamber 6 and the anode chamber 1 of the microbial electrolysis cell in sequence, while the voltage of the stabilized power supply 5 is fixed at -0.9 V. The electrogenic microorganisms attached to the surface of the anode electrode 2 metabolize the organic matter in artificially simulated wastewater to generate CO ₂ , H ⁺ and electrons, and the generated H ⁺ and electrons migrate to the cathode chamber 6, and chloroform, H ⁺ and electrons are in the A reaction occurs on the surface of the cathode electrode 7, and the specific chemical reaction equation is as follows:

Anode electrode

cathode electrode

Finally, it should be noted that obviously, the above-mentioned embodiments are only examples for clearly illustrating the utility model, rather than limiting the implementation manner. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. It is not necessary and impossible to exhaustively list all the implementation manners here. And the obvious changes or changes derived therefrom are still within the protection scope of the present utility model.

Claims (4)

1. A device utilizing microbial electrolysis cell technology to restore polluted groundwater in situ, characterized in that: comprising a sealed anode chamber and a sealed cathode chamber arranged in polluted groundwater, the chamber walls of the anode chamber and the cathode chamber are all open There are small holes; an anode electrode and a cathode electrode are respectively placed in the anode chamber and the cathode chamber; the anode electrode and the cathode electrode are respectively connected to the high potential end and the low potential end of the regulated power supply; the surface of the anode electrode is attached to the surface of the electrogenic microorganism. the 2. The device for in-situ restoration of polluted groundwater using microbial electrolysis cell technology as claimed in claim 1, characterized in that: said anode electrode material is carbon cloth, graphite felt, mesh glassy carbon, graphite or carbon fiber brush. the 3. the device utilizing microbial electrolysis cell technology to repair polluted groundwater in situ as claimed in claim 1, is characterized in that: described cathode electrode material is the carbon cloth of Pt modification, graphite felt, graphite or carbon fiber brush, or lead and copper. the 4. The device for in-situ restoration of polluted groundwater utilizing microbial electrolysis cell technology as claimed in claim 1, characterized in that: a sampling tube is arranged at the upper end of the anode chamber, and a gas collection pipe is arranged at the upper end of the cathode chamber. the