CN201134469Y - Microbial fuel cell to recover electricity from wastewater treatment - Google Patents

Abstract

A microbial fuel cell for recovering electrical energy from wastewater treatment, characterized in that the anode chamber of the microbial fuel cell is composed of a closed cylindrical or square pool body, the anode is suspended in the anode chamber, the cathode is fixed on the side wall of the anode chamber, and the cathode The inner surface is connected with the anode chamber, the outer surface is in contact with the air, the oxygen in the air diffuses freely from the outer surface of the cathode to the inner surface, the water inlet is located at the bottom of the pool wall, the water outlet is located at the upper part of the pool wall, and the wires leading from the anode are outside the anode chamber It is connected with the outer surface of the cathode to form an external circuit, and electrical components for recovery or electric energy utilization are arranged in the external circuit. The utility model has a simple structure, is not limited by the distance between the anode and the cathode, can build a device suitable for production scale, does not need external power to increase the oxygen content on the surface of the cathode, does not use a proton exchange membrane, and has low construction and operation costs. Waste water is purified while recovering electrical energy from the material.

Description

Microbial fuel cell to recover electricity from wastewater treatment

Technical field:

The utility model relates to a microbial fuel cell device capable of obtaining electric energy while removing organic matter in waste water, and belongs to the technical field of biomass energy recovery and utilization.

Background technique:

Biomass is a kind of renewable energy with abundant reserves. It can be used as an alternative energy source for fossil energy, and it can realize zero emission of CO ₂ , and the content of S and N is low, which can greatly reduce the greenhouse effect and environmental pollution. There are many types of biomass for renewable energy, and organic wastewater is one of them. The energy recoverable from organic wastewater currently mainly includes three types of methane, hydrogen and electricity, all of which are produced in the process of microbial degradation of organic matter.

The conversion of organic matter into methane gas through fermentation under anaerobic conditions is a traditional technical method for high-concentration organic wastewater treatment and energy recovery. Since methanogenic bacteria are extremely sensitive to environmental conditions, it is difficult to control suitable conditions to achieve anaerobic biological treatment systems. At the same time, methane is a greenhouse gas and is not an environmentally friendly energy material. Therefore, the application of this method is limited.

Hydrogen is considered to be one of the clean energy sources with the most development potential, and the extraction of hydrogen from wastewater by fermentation microorganisms is an effective way to obtain cheap hydrogen. But at present, the hydrogen conversion rate of this method is low, the total efficiency is less than 30% of the theoretical conversion rate, and only 15% of the organic matter energy in the wastewater can be converted into hydrogen form, which does not yet have the economic value of development and utilization, far from reality Applications are still a long way off.

A device that uses microorganisms to directly convert the chemical energy of organic substances in wastewater into electrical energy is called a microbial fuel cell (MFC). Because MFC can directly convert various organic matter chemical energy in wastewater into electrical energy, it not only has high energy conversion efficiency and no pollution, but also can purify wastewater while obtaining electrical energy, reducing or eliminating pollution, so it has attracted increasing attention.

At present, the typical design of MFC adopts a double-chamber structure. The anode chamber containing microorganisms is separated from the cathode chamber by a proton exchange membrane. The electrons generated during the degradation of organic matter in the anode chamber by anaerobic microorganisms are transmitted from the anode to the cathode chamber through an external circuit. At the same time, protons also enter the cathode chamber from the anode chamber through the proton exchange membrane, thereby forming a current loop, and connecting electrical components through an external circuit to recover or utilize electric energy, and oxygen molecules, protons and electrons combine in the cathode chamber to form water. Due to the use of proton exchange membranes and noble metal platinum electrodes, and the need to constantly fill the cathode chamber with air to supply oxygen to the cathode chamber, the typical MFC not only has a complex structure, high cost and internal resistance, but also consumes a lot of external power, which is limited. Its power output efficiency and popularization and application.

Chinese Patent Authorization Publication No. CN1164509C, the authorized publication date is September 1, 2004, the name is "a biofuel cell using wastewater and activated sludge for wastewater treatment", and discloses "a biofuel cell using wastewater as fuel The main points of the technical scheme of the biofuel cell are: adopt a double-chamber microbial fuel cell, separate the anode chamber and the cathode chamber with a proton exchange membrane, continuously blow nitrogen into the anode chamber during operation to maintain anaerobic conditions, and continuously ventilate the cathode chamber into the air to obtain a higher concentration of dissolved oxygen.” Although this utility model can use the action of microorganisms to obtain electricity while degrading organic wastewater, its structure is complicated, its construction cost is high, its internal resistance is high, and its operating cost is high. Promotion is difficult.

In recent years, research on the construction of air cathodes, proton exchange membranes or membrane-free single-chamber microbial fuel cells has achieved certain results, but still limited by electrode materials and structures, only small experimental devices with a size of a few centimeters to more than ten centimeters can be constructed. It is difficult to apply to the actual wastewater treatment process. For example, the Chinese Patent Authorization Publication No. CN1874040A, the authorized publication date is December 6, 2006, and the name is "a single-cell microbial battery using organic waste water as fuel", which discloses "a single-cell microbial battery using organic waste water as fuel Type microbial battery, the main point of its technical scheme is: adopt single-chamber microbial fuel cell, including the anode chamber filled with organic waste water and anaerobic microorganisms, the anode is located at the closed end of the anode chamber, the cathode is located at the open end of the anode chamber, and the anode chamber is closed, The proton exchange membrane is hot-pressed on the inner surface of the cathode. The electrons generated by the degradation of organic matter in the anode chamber by microorganisms pass through the anode to the cathode through the external circuit, and at the same time, the protons reach the cathode through the proton exchange membrane, and the oxygen in the air can directly diffuse in through the outer surface of the cathode. On the inner surface of the cathode, oxygen molecules, protons and electrons are combined to form water." This utility model simplifies the construction and operation of microbial fuel cells, and uses air cathodes, which do not require ventilation and oxygen supply during operation, greatly reducing operating costs. The utility model can also remove the proton exchange membrane, further reducing the cost. However, this utility model uses carbon cloth, carbon paper or other materials as the anode, which has the following disadvantages:

1. The surface area of the anode is very small, the number of microorganisms that can be accommodated is very small, and the ability to degrade organic matter and generate electricity is very limited;

2. Limited by the distance between the anode and the cathode, this utility model can only construct a microbial fuel cell with a small volume, which is difficult for practical application;

3. Although the utility model can not use the proton exchange membrane, because the scale of the device is too small, when the proton exchange membrane is not used, the trace oxygen diffused from the cathode into the anode chamber will have a great impact on the anaerobic environment of the anode chamber. Thus affecting the stability of power generation and operation;

4. Carbon cloth or carbon paper is expensive, brittle, and has high installation requirements, making it difficult to use on a large scale.

Utility model content:

The purpose of the utility model is to overcome the deficiencies in the existing technologies and devices for using microbial fuel cells to treat organic waste water and generate electric energy, and to provide a device with simple structure, low production cost, convenient operation, low operating cost, and large-scale construction. The microbial fuel cell that recovers electrical energy from wastewater treatment can be used in actual production to economically and effectively remove organic matter in wastewater and generate electrical energy.

According to the utility model, the above-mentioned purpose can be realized by the stainless steel wire anode-air cathode-no membrane-single-chamber microbial fuel cell, and the technical solution adopted by the utility model to solve technical problems is as follows:

The structural feature of the utility model is that the anode chamber of the microbial fuel cell is composed of a closed cylindrical or square pool body, the anode is suspended in the anode chamber, the cathode is fixed on the side wall of the anode chamber, the inner surface of the cathode is connected with the anode chamber, and the outer surface is connected with the anode chamber. In contact with air, the oxygen in the air diffuses freely from the outer surface of the cathode to the inner surface. The water inlet is located at the bottom of the pool wall, and the water outlet is located at the upper part of the pool wall. The wires drawn from the anode are connected to the outer surface of the cathode outside the anode chamber to form an external circuit. The electrical components used for recovery or electric energy utilization are set in the external circuit.

Structural features of the present utility model also are:

The anode suspended in the anode chamber adopts sponge-like stainless steel wire clusters which are also used as biological fillers, and the spongy stainless steel wire clusters can fill or half-fill the anode chamber.

The cathode adopts carbon cloth whose inner surface contains 5%-15% platinum catalyst. .

The utility model uses a microbial fuel cell device to simultaneously realize the purification of organic waste water and the recovery and utilization of biomass energy. Compared with the prior art, the beneficial effects of the utility model are reflected in:

1. The cathode of the utility model is in direct contact with the air, and while obtaining sufficient oxygen, there is no need to add an inflatable device and power, which greatly reduces the operating cost and construction cost;

2. The device of the utility model has a simple structure and can be easily combined with the currently commonly used sewage biological treatment process equipment. For example, it can be combined with an upflow anaerobic sludge bed reactor (UASB) or an anaerobic biological contact oxidation process, which can The newly built device can also be transformed from the existing device, which has strong engineering practicability;

3. The utility model uses clusters of stainless steel wires to form the anode, which completely breaks away from the limitations of the traditional carbon cloth, carbon paper or graphite rod anodes in terms of material performance, price, service life and installation, and reduces the construction difficulty of microbial fuel cells and cost, and the device is not limited by scale;

4. Due to the use of stainless steel wire cluster anodes in the utility model, the surface area of the anode is much larger than that of the traditional device, which can accommodate more microorganisms, and the surface of the anode is fully in contact with the wastewater during operation, and the wastewater on the surface is constantly updated, so that the microorganisms that grow in suspension in the anode chamber It can also participate in the degradation of organic matter and generate electricity, and the wastewater purification effect and electricity generation efficiency are higher;

5. Due to the use of stainless steel wire cluster anodes, the utility model gets rid of the restriction of the device scale by the distance between the anode and the cathode and the effective volume of the anode chamber in the traditional device, and can build a device suitable for production scale, realizing microbial fuel cell technology from the experiment from the laboratory to the engineering practice;

6. Since the scale of the device can be increased in this utility model, the total amount of microorganisms contained and the amount of wastewater treated per unit time increase, and the trace oxygen diffused from the cathode to the anode chamber can be consumed quickly, and the affected area is relatively the volume of the entire anode chamber Negligible, therefore, the proton exchange membrane, which is expensive, has a short service life and is difficult to install, can be completely eliminated, reducing the construction cost and difficulty of microbial fuel cells.

Description of drawings:

Fig. 1(a) is a structural schematic diagram of Example 1 of the microbial fuel cell described in the present invention.

Fig. 1(b) is a schematic diagram of the top view of Fig. 1(a).

Fig. 2(a) is a structural schematic diagram of Example 2 of the microbial fuel cell described in the present invention.

Fig. 2(b) is a schematic top view of Fig. 2(a).

Fig. 3(a) and Fig. 3(b) are the operating results of the treatment of glucose self-provided organic wastewater in Example 1 of the present utility model.

Numbers in the figure: 1 anode chamber, 2 anode, 3 cathode, 4 MFC cell body, 5 water inlet, 6 water outlet, 7 electrical components, 8 wires.

Detailed ways:

Further illustrate each embodiment of the present utility model and working process thereof below in conjunction with accompanying drawing.

Example 1:

Referring to Fig. 1 (a), Fig. 1 (b), the present embodiment stainless steel wire anode-air cathode-no membrane-single chamber microbial fuel cell comprises the anode chamber 1 that is made of MFC pool body 4, and anode 2 is suspended in anode chamber 1 Inside, the cathode 3 is fixed on the outside of the anode chamber 1 with a flange, the inner surface of the cathode 3 communicates with the inside of the anode chamber 1, the outer surface of the cathode 3 is in contact with the air, oxygen in the air can freely diffuse to the inner surface of the cathode 3, and anaerobic microorganisms adhere to the The surface of the anode 2 is suspended in the anode chamber 1 under the disturbance of the upflow of waste water. The side wall of the pool body 4 is provided with a water inlet 5 and a water outlet 6. The water inlet 5 is close to the bottom of the pool, and the water outlet 6 is close to the top of the pool. The wire 8 is connected to the outer surface of the cathode 3 outside the anode chamber 1 , and the electrical element 7 is connected between the wire 8 .

In specific implementation, the MFC pool body 4 can be built into a cylinder (as shown in Figure 1 (b)), or a square (as shown in Figure 2 (b)), and a reinforced concrete or steel structure with inner wall anti-corrosion and insulation treatment can be used , can also be constructed using FRP materials. The anode 2 is composed of sponge-like stainless steel wire clusters, suspended in the anode chamber 1, and can be filled with the anode chamber 1, or half-filled with the anode chamber 1, and the anode 2 can also be made of any material with good electrical conductivity, corrosion resistance, and non-biodegradable constitute. The cathode 3 can be made of carbon cloth, and the inner surface contains 5%-15% platinum catalyst.

The working process of the single-chamber microbial fuel cell in the present embodiment is:

Add anaerobic microbial strains in the anode chamber 1, the organic waste water flows into the anode chamber 1 from the water inlet 5 at the lower part of the side wall of the pool body 4, and slowly rises to the water outlet 6 at the upper part of the side wall of the pool body 4 to flow out of the anode chamber 1 . During the metabolic process, the anaerobic microorganisms attached to the surface of the anode 2 and suspended in the anode chamber 1 oxidize and degrade the organic substances in the waste water, and generate electrons and protons. The electrons are transmitted to the connecting wire 8 through the anode 2, and then reach through the external circuit. At the cathode 3, the protons generated at the same time also reach the inner surface of the cathode 3. The oxygen in the air diffuses from the outer surface of the cathode 3 to the inner surface of the cathode 3 under the push of the oxygen partial pressure difference. Under the action of the platinum catalyst, the oxygen, protons and electrons combine Generate water. Due to the continuous transmission of electrons, the external circuit forms a current, and the electrical energy is recovered or utilized through the electrical component 7 connected to the external circuit. While obtaining electric energy, due to the decomposition and transformation of anaerobic microorganisms, the concentration of organic matter in the wastewater is reduced, the wastewater is purified, and the microorganisms themselves obtain nutrients and continue to proliferate, which can treat more organic wastewater and generate more electricity. .

Using the single-chamber microbial fuel cell of this embodiment to treat laboratory self-prepared glucose wastewater, when the influent COD concentration is 496mg/L, the open circuit voltage of the microbial fuel cell is 461mV, and the highest voltage value at both ends of the external circuit 1000Ω resistor is 235mV, as As shown in Figure 3(a), the maximum power density obtained is 137mW/m ² (cathode). As shown in Figure 3(b), the COD concentration in the effluent drops to 60mg/L, the COD removal rate reaches 88%, and the Coulombic efficiency reaches 32.4%. The single-chamber non-membrane microbial fuel cell of the utility model can degrade the organic substances in the waste water while recovering the biomass energy to obtain the electric energy, so that the waste water can be purified.

Example 2:

Referring to Fig. 2 (a), Fig. 2 (b), the present embodiment stainless steel wire anode-air cathode-membrane-single-chamber microbial fuel cell, its composition and mode of operation are basically the same as the microbial fuel cell described in Example 1 , the difference is that the waste water is in a horizontal push-flow state in the anode chamber 1, which can reduce the height of the anode chamber 1, and is suitable for large-scale or buried organic wastewater treatment occasions.

Claims (2)

1, a kind of microbiological fuel cell that from waste water treatment, reclaims electric energy, it is characterized in that constituting the anode chamber (1) of microbiological fuel cell by the cylindrical or square pond body (4) of sealing, anode (2) hangs in the anode chamber (1), negative electrode (3) is fixed in the sidewall of anode chamber (1), the inner surface of negative electrode (3) is communicated with anode chamber (1), outer surface contacts with air, airborne oxygen freely diffuses to inner surface from cathode outer surface, water inlet (5) is positioned at the pool wall bottom, delivery port (6) is positioned at pool wall top, the lead (8) of drawing from anode (2) is outside in the anode chamber to connect and compose external circuit with cathode outer surface, is provided for reclaiming in described external circuit or the electric component (7) of utilization of power.

2, the microbiological fuel cell that from waste water treatment, reclaims electric energy according to claim 1, it is characterized in that the described anode (2) that hangs in the anode chamber (1) adopts the spongy stainless steel wire cluster of while as biologic packing material, described spongy stainless steel wire cluster can be full of or partly be full of anode chamber (1).

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