Electrically driven biofenton system and application thereof

Abstract

The application provides an electrically-driven biological Fenton system and application thereof, and specifically, a low-voltage electric field is externally applied on the basis of the biological Fenton system, oxygen is generated by electrode reaction, an anaerobic / aerobic cycle is constructed around the electrode, and the biological Fenton system is driven to run. Under anaerobic conditions, Shewanella can utilize respiratory metabolism to transfer electrons in the substrate to iron oxide to obtain cyclic ferrous iron; under the condition of a low electric field, the electrode can generate a certain amount of oxygen, and under aerobic conditions, Shewanella can utilize respiratory metabolism to generate hydrogen peroxide, therefore, the ferrous iron obtained by the anaerobic / aerobic cycle and the hydrogen peroxide can generate a Fenton reaction; in addition, through the active point on the surface of the electrode, the electrically-driven biological Fenton system can more effectively improve the pollutant removal capacity. The electrochemical reaction system is simple to operate, so that the system can be simply and effectively regulated by setting the surface electrochemical parameters, and has a good application prospect in groundwater treatment.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of environmental protection, and particularly relates to an electrically-driven biological Fenton system and application thereof. BACKGROUND

[0002] Microbial remediation technology has a high application prospect in water body and contaminated site remediation, and targeted bioremediation technology has been widely concerned due to its economy and green characteristics in groundwater remediation. However, the technology is often subject to the complex environment of groundwater and is difficult to remove multiple pollutants, especially the limited dissolved oxygen conditions in groundwater. For example, the biodegradation of chlorinated hydrocarbons usually relies on the dechlorination process of anaerobic organisms, and the highly stable compound dioxane mainly relies on the hydroxylation degradation process of aerobic microorganisms. Therefore, the targeted bioremediation technology for a single type of pollutant has been difficult to meet the complex and variable environmental geochemical conditions of groundwater, and the development of a general and efficient alternative technology is urgently needed.

[0003] The biological Fenton system utilizes active oxygen produced by microbial respiratory metabolism and iron oxides widely existing in nature to form a Fenton reaction to produce strong oxidants such as hydroxyl radicals, thereby achieving the degradation of multiple pollutants. The biological Fenton has been widely concerned due to its broad-spectrum, high efficiency and economy. However, the current driving mode of the biological Fenton is limited to the formation of anoxic-aerobic cycles through aeration, thereby realizing the cyclic generation of ferrous ions and active oxygen. However, the construction of anoxic / aerobic cycles through aeration has poor operability and controllability in groundwater or site remediation, air diffusion is blocked in the groundwater medium, and the pipeline deep underground requires high operation and maintenance costs. SUMMARY

[0004] The present application overcomes the shortcomings of the existing aeration-driven mode of the biological Fenton, and provides an electrically-driven biological Fenton system and application thereof. Oxygen is produced by electrode reaction through an external low-voltage electric field, anoxic / aerobic cycles are effectively constructed around the electrode, and the biological Fenton system is driven to operate. In addition, through the active sites on the electrode surface, the electrically-driven biological Fenton system can more effectively improve the pollutant removal capacity. The electrochemical reaction system is easy to operate, and the system can be simply and effectively regulated and controlled by setting the surface electrochemical parameters.

[0005] The technical solutions adopted by the present application are as follows:

[0006] In a first aspect, an electrically-driven biological Fenton system is provided. Shewanella MR-1 bacterial solution is added to an electrolytic reactor, and ferric citrate is added to maintain anaerobic conditions for a period of time. A graphite electrode is inserted, and a power supply is connected. The voltage is set and maintained, water is electrolyzed to produce oxygen, and an electrically-driven biological Fenton system is established.

[0007] The specific establishment steps of the above electrically-driven biological Fenton system include:

[0008] (1)Shewanella MR-1 is cultured in LB medium to logarithmic growth phase, MR-1 is collected by centrifugation at 6000g and washed with physiological saline;

[0009] (2) The bacteria are collected and resuspended in anaerobic LS medium or medium, and the OD600 is adjusted to 1.0;

[0010] (3) The above bacteria solution is added to the electrolytic reactor, and 10 mM ferric citrate (III) is added, and the anaerobic condition is maintained for 4-8 hours;

[0011] (4) Insert the graphite electrode, connect the power supply, and keep the voltage at 2.0V, and the electrically driven microbial Fenton reaction can be carried out.

[0012] In the above scheme, the electrically driven biological Fenton system mainly consists of two parts, one is the biological Fenton reaction based on Shewanella, the key of which is that under anaerobic conditions, Shewanella can utilize respiratory metabolism to transfer electrons to iron oxide to obtain recycled ferrous iron, and under aerobic conditions, Shewanella can utilize respiratory metabolism to produce hydrogen peroxide, therefore, the ferrous iron and hydrogen peroxide obtained by anaerobic / aerobic cycle can produce Fenton reaction; The second key point of the electrically driven biological Fenton system is the electrode reaction, under low electric field conditions, the electrode can produce a certain amount of oxygen, which is utilized by Shewanella to produce hydrogen peroxide, and the adjustment of electrochemical parameters can realize the oxygen production rate, thereby regulating the degradation effect of the system. In addition, the active site of the electrode may also promote the adsorption and degradation of pollutants.

[0013] In the second aspect, the application of the above-mentioned electrically driven biological Fenton system in water body remediation, especially in the remediation of groundwater pollution sites containing refractory organic pollutants, is provided.

[0014] The beneficial effects of the present application are as follows:

[0015] 1. The present application can effectively drive Shewanella to produce biological Fenton reaction by applying low voltage electric field;

[0016] 2. The electrically driven biological Fenton system can be constructed by using cheap electrodes such as activated carbon and graphite, and the low voltage electric field can be powered by green energy such as solar energy, effectively reducing the cost;

[0017] 3. The electrically driven mode avoids the pipeline laying and maintenance cost required by aeration, and can effectively avoid the adverse factors such as unstable aeration flow pressure;

[0018] 4. The electrically driven biological Fenton system is simple to regulate and can be accurately regulated by setting the surface electrochemical parameters;

[0019] 5. The process is easy to popularize and easy to apply in actual site repair. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings obtained according to these drawings without creative labor are still within the scope of the present application.

[0021] Figure 1 The figure is a schematic diagram of the principle of the present application.

[0022] Figure 2 The figure is a comparison of the effects of the electrically driven Fenton system and the ordinary biological Fenton system under different carbon source addition conditions. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the present application more clear, the present application will be further described in detail below with reference to the drawings.

[0024] Example 1

[0025] (1) Shewanella MR-1 was cultured in LB medium to the logarithmic growth phase, and MR-1 was collected by centrifugation at 6000g and washed with 0.9% NaCl three times;

[0026] (2) The bacterial cells were collected and resuspended in anaerobic LS medium or medium, and the OD600 was adjusted to 1.0;

[0027] (3) The above bacterial solution was added to an electrolytic reactor, and 10 mM ferric citrate (III) was added, and the anaerobic condition was maintained for 6 hours;

[0028] (4) A 1.5 cm x 1.5 cm graphite electrode was inserted, the power supply was turned on, and the voltage was maintained at 2.0 V, and the electrically driven microbial Fenton reaction was carried out.

[0029] Comparative Example 1

[0030] Establishment of an ordinary biological Fenton system:

[0031] (1) Collect Shewanella MR-1 bacteria in the logarithmic growth phase, resuspend in anaerobic LS medium after centrifugation and washing, and adjust the OD600 to 1.0; (2) Add 10 mM ferric citrate (III) to the above bacterial solution and maintain anaerobic conditions for 6 hours; (3) Air is introduced into the above solution (flow rate of 10 mL / min), and maintained for 12 hours; (4) Nitrogen gas is introduced into the above solution to convert the system to anaerobic conditions, and after maintaining for 6 hours, air is introduced again for multiple anaerobic-aerobic cycles, thereby carrying out a biological Fenton reaction.

[0032] The comparative experiment of example 1 and comparative example 1 is shown in the following table Figure 2 , Figure 2 The 72h dioxane degradation effect comparison chart of the electrically driven Fenton system provided by example 1 and the ordinary biological Fenton system under different carbon source addition conditions is shown in the following table. The degradation rates of the electrically driven biological Fenton system are 72.32% and 82.58% when the carbon source concentrations are 1mM and 10mM respectively; the degradation rates of the ordinary biological Fenton system are 29.57% and 55.15% when the carbon source concentrations are 1mM and 10mM respectively. It can be obviously seen that the degradation effect of the electrically driven biological Fenton system on pollutants is significantly better than that of the ordinary biological Fenton system under the same carbon source supply condition.

[0033] In summary, the electrically driven biological Fenton system provided by the present application is different from the existing aeration driven biological Fenton system. The present application utilizes low-voltage electric field electrolysis of water to produce oxygen, forms anoxic / aerobic microcirculation, and further drives the biological Fenton reaction to proceed, has the characteristics of simple operation, good effect and high controllability, and constructs an electrically driven mode of biological Fenton.

[0034] The above only discloses the preferred embodiments of the present application, of course cannot limit the scope of the rights of the present application, therefore the equivalent changes made according to the claims of the present application still belong to the scope covered by the present application.

Claims

1. A method for constructing an electrically driven bio-Fenton system, characterized in that: Shewanella bacterial solution and ferric citrate were added to the electrolysis reactor and anaerobic conditions were maintained for a period of time. Electrodes were inserted and the power supply was turned on. The voltage was set and maintained, and water was electrolyzed to produce oxygen, thus establishing an electrically driven biological Fenton system. The steps for establishing the electrically driven biological Fenton system include: (1) Shewanella MR-1 was cultured in LB medium to the logarithmic growth phase, collected by centrifugation at 6000g and washed with physiological saline. (2) Collect the bacterial cells and resuspend them in anaerobic LS medium or medium, and adjust OD600 = 1.0; (3) Add the above Shewanella MR-1 bacterial solution to the electrolytic reactor, and add ferric citrate at a concentration of 10 mM, and maintain anaerobic conditions for 4-8 hours; (4) Insert the graphite electrode, turn on the power supply, and keep the voltage at 2.0V to carry out the electrically driven microbial Fenton reaction.

2. The application of the electrically driven biological Fenton system constructed by the method for constructing an electrically driven biological Fenton system as described in claim 1 in water remediation.

3. The application of the electrically driven bio-Fenton system constructed by the method for constructing an electrically driven bio-Fenton system as described in claim 1 in the remediation of groundwater contaminated sites containing recalcitrant organic pollutants.

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