CN104961240A - Waste leachate treatment method and microbial electrolytic battery - Google Patents

Abstract

The invention discloses a treatment method of landfill leachate and a microbial electrolytic cell suitable for the landfill leachate. The method comprises the following steps: performing anaerobic fermentation pretreatment on the landfill leachate to make the landfill leachate Organic pollutants are intercepted, adsorbed and decomposed by anaerobic microorganisms, and degrade macromolecular organic matter or destroy the long-chain structure of macromolecular organic matter to improve its biodegradability; then use microbial electrolysis cells to treat the fermented biogas slurry. The invention has a good treatment effect on the landfill leachate, and the microbial electrolysis battery can obtain different forms of energy while performing biological treatment on the landfill leachate.

Description

A treatment method for landfill leachate and microbial electrolysis battery

technical field

The invention belongs to the intersecting fields of bioelectrochemistry, environment and bioenergy, and in particular relates to a treatment method for landfill leachate.

Background technique

Municipal landfill leachate is a kind of high-concentration wastewater that is difficult to treat. The composition and structure of pollutants in the water are complex and difficult to be directly degraded by biology. Some wastewater contains high salinity. The leachate of urban waste landfill is a kind of complex and highly polluting organic wastewater, which will cause serious pollution to both surface water and groundwater. Its pollution and impact on groundwater, soil and ecology often last for a long time It takes a long time, ranging from a few years to decades or even hundreds of years. Manual treatment and repair will pay a high price, and it is often not feasible. Therefore, proper disposal of landfill leachate is the most important measure to prevent secondary pollution.

The processing methods about leachate at home and abroad mainly include the following: a. physical and chemical treatment methods, such as coagulation sedimentation, chemical precipitation, adsorption, membrane separation, etc.; b. biological treatment methods, such as aerobic biological treatment, anaerobic biological treatment , Aerobic-anaerobic joint treatment, oxidation pond, etc.; c. Land treatment method.

For biological treatment methods, domestic and foreign researchers have carried out a lot of research work on the biodegradation of landfill leachate, most of which use activated sludge method, biofilm or anaerobic biofilter to degrade landfill leachate. The aerobic biological treatment process in the biological method is effective, but it needs large-scale aeration, and the capital construction cost and operation management cost are high. Although the anaerobic biological treatment process can save floor space and power consumption, it is easily affected by environmental conditions and interfering substances, and the treatment effect will deteriorate with the decrease of temperature and the extension of years. Therefore, the combination of anaerobic and aerobic treatment is generally used now. Although this process has high treatment efficiency, the process is relatively complicated, and the utilization of organic matter in wastewater is not considered.

Microbial electrolysis cell (MEC) is an electrogenic microorganism that grows on the surface of the anode of the MEC, mainly electrogenic bacteria, which oxidize organic matter to generate electrons, protons and CO ₂ , and the electrons are collected by the anode and then reach the cathode through an external circuit, where Combining with protons produces hydrogen gas. When sodium acetate is used as the substrate, the electrode reaction is shown in the following formula:

Anode reaction:

Cathodic reaction: 2H ⁺ +2e ^- → H ₂

Overall response:

Microbial electrolysis cell is a new technology that combines sewage treatment and energy generation, which has been developed rapidly in recent years. It can obtain different forms of energy while biologically treating sewage. As a new process for sewage treatment, it has attracted widespread attention. MEC technology not only overcomes the shortcomings of the traditional wastewater biological treatment process, but also the recovered energy can reduce the cost of sewage treatment. Today, with the increasingly serious problems of energy, environment and water resources, MEC can achieve the three goals of reducing pollutant emissions, dependence on fossil fuels and recycling sewage, achieving a win-win situation for the economy and the environment. This is the resource of landfill leachate. Chemical treatment provides a new idea, but there is still no effective use of this method to deal with the device and treatment method of garbage permeate.

Contents of the invention

The object of the present invention is to solve the above problems and provide a treatment method for landfill leachate, which is simple, easy to implement, low in cost and high in efficiency.

The invention provides a treatment method for landfill leachate, the steps are as follows:

(1) The landfill leachate is subjected to anaerobic fermentation pretreatment.

This step can make the organic pollutants in the landfill leachate be intercepted, adsorbed and decomposed by anaerobic microorganisms, degrade the macromolecular organic matter or destroy the long-chain structure of the macromolecular organic matter, and improve its biodegradability. The anaerobic pre-fermentation is A type of technology well known to those skilled in the art, those skilled in the art can select a suitable anaerobic fermentation process according to needs.

(2) Treating the biogas slurry fermented in step (1) by using a microbial electrolysis cell.

Preferably, in the step (1), the pH is controlled at neutral, and the fermentation temperature is 30-40°C. More preferably, the system can be stirred at a stirring rate of 15-25 r/s.

Preferably, in the step (1), methanol, ammonium nitrate, etc. are used to adjust the carbon-to-nitrogen ratio of the fermentation broth to 20-30:1.

Preferably, the conductive material of the microbial electrolysis cell anode (12) is carbon cloth, carbon paper, graphite felt, graphite particles and graphite brushes; the conductive material of the negative electrode (2) is a carbon felt cathode and a titanium cathode cylinder.

Preferably, the microbial electrolysis cell in the step (2) includes an outer cylinder, an inner cylinder and a cathode, and a cathode enriched with electrogenic bacteria is filled between the outer cylinder and the inner cylinder.

The present invention also provides a microbial electrolysis cell for garbage permeate, comprising a cathode, an anode, an outer cylinder, an inner cylinder, a water inlet and a water outlet, and it is characterized in that the outer cylinder, the inner cylinder and the cathode are sequentially arranged from outside to inside Arranged coaxially, the water inlet is arranged at the bottom end of the outer cylinder, and the water outlet is arranged at the upper end of the treatment device.

Preferably, an electrolyte solution containing electrogenic bacteria is filled between the inner cylinder and the outer cylinder.

Preferably, the conductive material of the anode is carbon cloth, carbon paper, graphite felt, graphite particles and/or graphite brushes; the conductive material of the cathode is carbon felt cathode and/or titanium cathode cylinder.

In one embodiment of the present invention, the microbial electrolysis cell device used comprises a uniform water distributor (1), a cathode (2), a plastic porous inner cylinder (3), a glass outer cylinder (4), an electrolyte (5), Sealing membrane port (6), glass top cover (7), water outlet (8), control valve (9), gas collection bag (10), power supply (11), anode (12), water inlet (13); The reactor comprises a glass outer cylinder (4), a plastic porous inner cylinder (3) and a cathode (2) arranged coaxially from outside to inside in sequence. A water inlet (13) is provided at the bottom of the glass outer cylinder (4), a water outlet (8) is provided at the upper end, and the top air outlet communicates with the gas collection bag (10).

A cathode (2) enriched with electricity-generating bacteria is filled between the glass outer cylinder (4) and the plastic porous inner cylinder (3) of the microbial electrolysis cell. The positive pole of the external power supply (11) is connected to the anode (12) through a wire, and its negative pole is connected to the cathode (2) through a wire. The resistor is connected in series in the external circuit, and the current in the external circuit is calculated by measuring the voltage across the external resistor. The hydrogen generated by the cathode is discharged from the gas outlet at the top of the cathode chamber and collected by the gas collection bag (10).

The method of the present invention has relatively low operating costs and high treatment efficiency, and can be widely used in various countries around the world; combined with microbial electrolytic cells to treat landfill leachate, it not only overcomes the shortcomings of traditional wastewater biological treatment processes, but also reduces the energy recovered. The cost of sewage treatment can achieve the three goals of reducing pollutant emissions, dependence on fossil fuels, and sewage recycling, achieving a win-win situation for the economy and the environment.

Description of drawings

Fig. 1 is a structural schematic diagram of the microbial electrolysis battery of the present invention.

Drawing logo:

1: Uniform water distributor; 2: Cathode; 3: Plastic porous inner cylinder; 4: Glass outer cylinder; 5: Electrolyte; 6: Sealing film port; 7: Glass top cover; 8: Water outlet; 9: Control valve ; 10: gas collection bag; 11: power supply; 12: anode; 13: water inlet.

Detailed ways

The following will explain the present invention by means of figures and examples, which are only used as explanations of the present invention and not as limitations.

The present invention adopts following method to process landfill leachate:

(1) The landfill leachate is subjected to anaerobic fermentation pretreatment, so that the organic pollutants in the landfill leachate are intercepted, adsorbed and decomposed by anaerobic microorganisms, degrade the macromolecular organic matter or destroy the long-chain structure of the macromolecular organic matter, and improve its bioavailability biochemical. Here, the anaerobic fermentation pretreatment is a common treatment method in the field, and those skilled in the art can select an appropriate anaerobic fermentation treatment method according to needs, and details are not repeated here.

(2) Treating the biogas slurry fermented in step (1) by using a microbial electrolysis cell.

In the aforementioned step (1), the pH is recommended to be controlled at neutral, the fermentation temperature is 30-40°C, and the stirring rate is 15-25r/s.

In the aforementioned step (1), methanol, ammonium nitrate, etc. can be used to adjust the carbon-to-nitrogen ratio of the fermentation broth to 20-30:1.

Referring to Fig. 1, the present invention uses the following microbial electrolytic cell to complete the treatment of garbage permeate, and the microbial electrolytic cell device includes a uniform water distributor (1), a cathode (2), a plastic porous inner cylinder (3), a glass outer cylinder (4), electrolyte (5), sealing membrane port (6), glass top cover (7), water outlet (8), control valve (9), gas collection bag (10), power supply (11), anode ( 12), a water inlet (13); the reactor includes a glass outer cylinder (4), a plastic porous inner cylinder (3) and a cathode (2) arranged coaxially from outside to inside in sequence. A water inlet (13) is provided at the bottom of the glass outer cylinder (4), a water outlet (8) is provided at the upper end, and the top air outlet communicates with the gas collection bag (10).

In the above device, the conductive material of the anode (12) is carbon cloth, carbon paper, graphite felt, graphite particles and/or graphite brushes; the conductive material of the cathode (2) is a carbon felt cathode and/or a titanium cathode cylinder.

The cathode (2) enriched with electrolytic bacteria is filled between the glass outer cylinder (4) and the plastic porous inner cylinder (3) of the microbial electrolysis cell in (2). The positive pole of the external power supply (11) is connected to the anode (12) through a wire, and its negative pole is connected to the cathode (2) through a wire. The resistor is connected in series in the external circuit, and the current in the external circuit is calculated by measuring the voltage across the external resistor. The hydrogen generated by the cathode is discharged from the gas outlet at the top of the cathode chamber and collected by the gas collection bag (10).

Here, the electrogenic bacteria can be selected from Shewanella, Geobacteriaceae or Arxobacter. The inventors suggest that mixed bacteria can be used here because the mixed bacteria are not only easy to operate and have a wide range of sources, but also the production of mixed bacteria The electrical performance is better than that of pure bacteria. The concentration of electrogenic bacteria is a conventional addition amount in the field, which can be flexibly adjusted by those skilled in the art according to needs, for example, 0.3-1.2 g/L is selected.

When using the method and device of the present invention to treat landfill leachate, the specific operations are as follows:

Perform anaerobic fermentation pretreatment on the landfill leachate, so that the organic pollutants in the landfill leachate are intercepted, adsorbed and decomposed by anaerobic microorganisms, and then a sleeve-type microbial electrolytic cell is constructed, and the glass outer cylinder and the plastic porous inner cylinder are filled There is graphite felt enriched with electrogenic photosynthetic bacteria. The positive electrode of the external power supply is connected to the graphite felt through the titanium wire, and the negative electrode is connected to the titanium cathode cylinder through the titanium wire. A 10Ω resistor is connected in series in the external circuit, and the current in the external circuit is calculated by measuring the voltage across the external resistor. The hydrogen gas generated by the cathode is discharged from the gas outlet at the top of the cathode chamber and collected by the gas collection bag.

Claims (9)

1. A treatment method for landfill leachate, comprising the following steps: (1) carry out anaerobic fermentation pretreatment to landfill leachate; (2) Treating the biogas slurry fermented in step (1) by using a microbial electrolysis cell. 2. The method according to claim 1, characterized in that, in step (1) during the anaerobic fermentation pretreatment process, the pH is controlled to be neutral, and the fermentation temperature is 30-40°C. 3. The method according to claim 1, characterized in that, in step (1) during the anaerobic fermentation pretreatment process, the carbon-to-nitrogen ratio of the fermentation liquid phase is controlled to be 20-30:1. 4. The method according to claim 3, characterized in that, in the step (1) anaerobic fermentation pretreatment process, methanol or ammonium nitrate is used to adjust the carbon-nitrogen ratio in the fermentation liquid phase. 5. method according to claim 1, is characterized in that, the conductive material of anode in the microbial electrolysis cell in described step (2) is carbon cloth, carbon paper, graphite felt, graphite particle and/or graphite brush; The conductive material is a carbon felt cathode and/or a titanium cathode cartridge. 6. The method according to claim 1, wherein the microbial electrolytic cell comprises an outer cylinder, an inner cylinder and a negative electrode in the step (2), and the inner cylinder and the outer cylinder are filled with an electrolytic cell containing electricity-producing bacteria. electrolyte. 7. A microbial electrolytic cell for garbage permeate treatment, comprising a cathode, an anode, an outer cylinder, an inner cylinder, a water inlet and a water outlet, characterized in that the outer cylinder, the inner cylinder and the cathode are sequentially arranged from outside to inside Arranged coaxially, the water inlet is arranged at the bottom end of the outer cylinder, and the water outlet is arranged at the upper end of the treatment device. 8. The microbial electrolysis battery according to claim 7, characterized in that an electrolyte solution containing electricity-producing bacteria is filled between the inner cylinder and the outer cylinder. 9. microbial electrolysis cell according to claim 7, is characterized in that, the conductive material of described anode is carbon cloth, carbon paper, graphite felt, graphite particle and/or graphite brush; The conductive material of described negative electrode is carbon felt Cathodes and/or titanium cathode cartridges.