CN114634241A

CN114634241A - Method for simultaneously removing sulfate and florfenicol in water

Info

Publication number: CN114634241A
Application number: CN202210359928.3A
Authority: CN
Inventors: 骆海萍; 梁競文; 刘广立; 张仁铎
Original assignee: Sun Yat Sen University
Current assignee: Sun Yat Sen University
Priority date: 2022-04-07
Filing date: 2022-04-07
Publication date: 2022-06-17
Anticipated expiration: 2042-04-07
Also published as: CN114634241B

Abstract

The invention discloses a method for simultaneously removing sulfate and florfenicol in water, which comprises the following steps: (1) adding a domesticated sulfate reducing bacteria sulfate substrate into an anaerobic bottle, and carrying out aeration reaction under a constant-temperature oscillation state; (2) adding the bacterial liquid obtained in the step (1) and a sulfate substrate into a cathode chamber of a photoelectric coupling microbial reactor, wherein anolyte of the photoelectric coupling microbial reactor is a sulfate solution of 5 g/L; (3) placing the reactor anode in the step (2) under an ultraviolet light source to carry out photo-anode electricity generation; (4) florfenicol is added into the cathode chamber of the reactor in the step (3), and the reactor is cultured for one week under the conditions of 27 ℃ and 1.2V voltage, so as to remove sulfate and florfenicol. The invention is improved on the basis of a photoelectrochemical cell, microbes are added at the cathode, a photoelectric coupling microbial electrolysis system is built, and sulfate and florfenicol in water can be effectively removed by combining the photoanode electricity generation and microbial degradation technologies, so that the biological toxicity of the system is reduced.

Description

Method for simultaneously removing sulfate and florfenicol in water

Technical Field

The invention relates to the field of water pollution control, in particular to a method for simultaneously removing sulfate and florfenicol in water.

Background

An antibiotic is a chemical produced by the metabolism of a microorganism and inhibits the growth and activity of the microorganism. The method is widely applied to industries such as medical treatment, agriculture, animal husbandry, aquaculture and the like. However, the antibiotics can not be effectively removed in the traditional sewage biological treatment, the part of the antibiotics which can be metabolized by organisms is very limited, and most of the antibiotics can be discharged into natural water in the form of raw medicines to cause pollution. With the migration of antibiotics in water environments, various antibiotics are currently detected in surface water, ground water and part of drinking water all over the world. The environmental antibiotics have many effects on animals, plants and human beings, such as generating toxicity to aquatic organisms, reducing human immunity, promoting the generation of resistant bacteria and resistant genes, and the like, thereby breaking ecological balance.

Wherein, florfenicol is widely applied to the fields of livestock, poultry, aquaculture and the like as one of antibiotics. Florfenicol is frequently detected in water bodies in the global scope at present, and the florfenicol can induce bacterial drug resistance to cause serious harm if existing in the environment for a long time, so that the florfenicol pollution control is particularly important.

At present, the treatment of antibiotics mainly comprises a physicochemical method and a biological method. The physicochemical methods can effectively reduce the antibiotic concentration in the sewage, but consume a large amount of electric energy and have complex material synthesis modes, and the methods only convert the antibiotic concentration into complex compounds with low toxicity and relatively stable property through hydroxyl oxidation or bond breaking and other ways, some intermediate products with higher toxicity than the original substances can be generated even in the degradation process, and because the intermediate products cannot be mineralized finally, the degradation products cannot participate in the substance circulation of the nature, and the complex compounds are accumulated in the nature and are not easy to degrade to form secondary pollution. Biological methods achieve antibiotic removal by using growth metabolism of plants and microorganisms (bacteria, fungi, algae), biocatalysts (enzymes), and the like. However, biodegradation of organic contaminants requires an electron donor (acetate or hydrogen) to remove its biocidal activity, and thus, microorganisms can have some limitations in situ remediation due to the limitations of the associated electron donor.

In addition to antibiotics, sulfate is also one of the non-negligible water pollutants. The sulfate is the most stable existing form of sulfur in the water body, so that the sulfate wastewater can stably exist in the water body for a long time and is difficult to naturally purify and eliminate. After the sulfate wastewater enters a natural environment, environmental problems such as water body acidification, soil hardening, aquatic plant death and the like can be caused, and the benign development of an ecological system is influenced; in addition, when sulfate enters drinking water through a water supply system, the sulfate can also cause digestive system diseases of human beings by inhibiting the activity of pepsin, and has great threat to human health.

In the prior art, a method for simply and efficiently removing florfenicol antibiotics in water and simultaneously removing sulfate in water is lacked, so that a good water purification effect is achieved.

Disclosure of Invention

In order to solve the technical problems and overcome the defects of the prior art, the invention provides a method for simultaneously removing sulfate and florfenicol in water, which utilizes an autotrophic biological cathode of a photoelectric coupling microbial electrolysis system to simultaneously remove sulfate and florfenicol in water, has short treatment period and good treatment effect, is improved on the basis of a photoelectrochemical battery, adds microbes to the cathode, and builds the photoelectric coupling microbial electrolysis system. The combination of photoanode electrogenesis and microbial degradation technology can effectively remove sulfate and florfenicol in water and reduce the biological toxicity of a system, and the method is realized by the following technical scheme: a process for the simultaneous removal of sulfate and florfenicol from water comprising the steps of:

a process for simultaneously removing sulfate and florfenicol from water comprising the steps of:

(1) adding a domesticated sulfate reducing bacteria sulfate substrate into an anaerobic bottle, and carrying out aeration reaction under a constant-temperature oscillation state;

(2) adding the bacterial liquid obtained in the step (1) and a sulfate substrate into a cathode chamber of a photoelectric coupling microbial reactor, wherein anolyte of the photoelectric coupling microbial reactor is 5g/L sulfate solution;

(3) placing the reactor anode in the step (2) under an ultraviolet light source to carry out photo-anode electricity generation;

(4) florfenicol is added into the cathode chamber of the reactor in the step (3), and the reactor is cultured for one week under the conditions of 27 ℃ and 1.2V voltage, so as to remove sulfate and florfenicol.

In one embodiment, in the step (2), the ratio of the bacterial liquid to the sulfate matrix is 1: 1.

In one embodiment, in the step (2), the applied voltage of the photocoupling microbial reactor is 1.2V; in the step (3), the intensity of the ultraviolet light source is 13mW/cm 2, and the reaction time for generating electricity by the photo-anode is 36 hours.

In one embodiment, the step (1) specifically includes:

1) adding domesticated sulfate reducing bacteria and a sulfate substrate into a 100ml anaerobic bottle;

2) introducing H with the mixing ratio of 1:4 into an anaerobic bottle every 2 days₂-CO₂Mixing gas, and half replacing the bacterial liquid obtained in the step 1) with a fresh matrix every 4 days;

the anaerobic bottle is placed in a constant temperature oscillator.

In one embodiment, the constant temperature oscillator is at 30 deg.C and 180 r/min.

In one embodiment, the domesticated sulfate reducing bacteria and the sulfate substrate in step 1) are inoculated at a ratio of 1:10, and the aeration time in step 2) is 5 min.

In one embodiment, in the step (2), the photocoupling microbial reactor is set up by the following steps:

(a) ultrasonically cleaning FTO conductive glass by using a mixed solution of water, acetone and isopropanol in a ratio of 1:1:1, and naturally airing;

(b) mixing 40mL of pure water and 40mL of concentrated hydrochloric acid with the mass concentration of 36.5-38%, adding the mixture into a polytetrafluoroethylene lining of a reaction kettle, and then adding 1.3mL of butyl titanate;

(c) putting the FTO conductive glass in the step (a) into the inner liner of the reaction kettle in the step (b), wherein the conductive surface faces upwards, and transferring the reaction kettle to an air-blast drying box after a cover is covered;

(d) weaving carbon brushes by using graphite fiber bundles, connecting each strand of the carbon brushes by using titanium wires, and screwing the carbon brushes by using pliers;

(e) placing the carbon brush in the step (d) in a muffle furnace for heat treatment;

(f) building a reactor, the anode electrode being the TiO coated anode electrode prepared in step (c)₂The cathode of the FTO conductive glass is the carbon brush electrode prepared in the step (e), and two polar chambers are separated by a cation exchange membrane.

In one embodiment, in the step (c), the reaction temperature is 150 ℃ and the reaction time is 5 h.

In one embodiment, in the step (d), the carbon brushes have 16 strands, a length of 4cm and a width of 3.5 cm.

In one embodiment, in step (e), the heat treatment condition is 450 ℃ for 30 min.

Compared with the prior art, the invention has the following beneficial effects:

(1) the invention uses titanium dioxide as a photoelectric material, and combines a photoelectrochemical cell and an autotrophic microbial electrolysis cell to construct a photoelectric coupling microbial electrolysis system. The photoelectrochemical cell can combine the decomposition of water and the absorption of solar energy into one reactor, reducing the supply of external energy. The autotrophic microbial electrolysis cell can realize sulfate reduction and organic matter degradation. In addition, a part of oxygen generated by anode electrolysis water of the photoelectric coupling microbial electrolysis system formed by combining the two is transferred to the cathode through the ion exchange membrane, so that the biological cathode becomes a micro-oxygen environment, the micro-oxygen environment enables aerobic, anaerobic and facultative microorganisms to coexist in the same system, and then the microorganisms of the system are abundant in types, and can interact with one another among the microorganisms to jointly complete the degradation of organic substances. Therefore, the photoelectric coupling microbial electrolysis system is used for treating water polluted by the florfenicol, is beneficial to further removing the sulfate and the florfenicol by sulfate reducing bacteria on the cathode, overcomes the defects of the prior art, and realizes the good effect of simultaneously removing the sulfate and the florfenicol.

(2) The method has the advantages of short treatment period and good treatment effect, and the removal rate of sulfate is more than 80 percent, and the removal rate of florfenicol is more than 90 percent.

Drawings

FIG. 1 is a graph showing the effect of florfenicol concentration on reaction current

FIG. 2 is a graph of the effect of florfenicol concentration on sulfate reduction rate

FIG. 3 is a graph of the effect of florfenicol concentration on sulfate reduction

FIG. 4 is a graph of the effect of florfenicol concentration on the rate of divalent sulfur production

FIG. 5 is a graph of the effect of florfenicol concentration on the production of divalent sulfur

FIG. 6 is a graph showing the effect of different florfenicol initial test concentrations on the removal efficiency

FIG. 7 is a schematic diagram of florfenicol reduction reaction under photoelectric coupling microbial electrolysis system

FIG. 8 is a florfenicol reduction reaction schematic diagram under a photoelectric system

Detailed Description

The technical scheme in the embodiment of the invention is clearly and completely described below; it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and all other embodiments obtained by those skilled in the art without any inventive work are within the scope of the present invention.

Example 1

The embodiment provides a method for simultaneously removing sulfate and florfenicol in water, which comprises the following steps:

(1) adding domesticated sulfate reducing bacteria into 100ml anaerobic bottleA sulfate matrix; introducing H with the mixing ratio of 1:4 into the anaerobic bottle every 2 days₂-CO₂Mixing gas, and half-replacing the reacted bacterium liquid with a fresh matrix every 4 days; the anaerobic jar was placed in a constant temperature shaker at 30 ℃ and 180 r/min.

Wherein the inoculation ratio of the domesticated sulfate reducing bacteria and the sulfate matrix in the step (1) is 1:10, and the ventilation time is 5 min.

In the step (2), the ratio of the bacterial liquid to the sulfate matrix is 1: 1; the external voltage of the photoelectric coupling microbial reactor is 1.2V; in the step (3), the intensity of the ultraviolet light source is 13mW/cm 2, and the reaction time for generating electricity by the photo-anode is 36 hours.

In the step (2), the photoelectric coupling microbial reactor is built by adopting the following steps:

(d) weaving carbon brushes by using graphite fiber bundles, connecting each strand of the carbon brushes by using titanium wires and screwing the carbon brushes by using a pliers;

(f) building a reactor, the anode electrode being the TiO coated anode electrode prepared in step (c)₂The cathode of the FTO conductive glass is the carbon brush electrode prepared in the step (e), and two electrode chambers are separated by a cation exchange membrane.

Wherein, in the step (c), the reaction temperature is 150 ℃, and the reaction time is 5 hours; in the step (d), the carbon brushes are 16 strands, 4cm in length and 3.5cm in width; in the step (e), the heat treatment condition is 450 ℃ for 30 min.

Example 2

Influence of florfenicol concentration on reaction Current

The florfenicol concentration can change the activity, the electronic utilization effect and the sulfate reduction capability of sulfate reducing bacteria in the solution, and is an important factor influencing whether the sulfate reducing bacteria can normally work in the system. A photoelectric coupling microbial system is constructed to reduce and remove norflorfenicol in water, the florfenicol gradient is set to be 0mg/L, 1mg/L, 3mg/L and 5mg/L, and the influence of the florfenicol on the activity and the electronic utilization effect of sulfate reducing bacteria is researched.

The result shows (see figure 1), the existence of florfenicol strengthens the utilization of the sulfate reducing bacteria to electrons, and the current intensity of the reactor is obviously improved under the condition of the existence of low concentration of florfenicol (1mg/L), which shows that the concentration of florfenicol does not inhibit the growth of the sulfate reducing bacteria; when the concentration of florfenicol is increased to 3mg/L, the current intensity is slightly reduced; when the concentration of the florfenicol is increased to 5mg/L, the current intensity is increased back to the original level when the concentration of the florfenicol is 1 mg/L. The method of the invention does not inhibit the sulfate reducing bacteria, but the strengthening effect of the low-concentration florfenicol on the sulfate reducing bacteria is far higher than the inhibiting effect of the florfenicol on the sulfate reducing bacteria. In conclusion, the florfenicol added into the system is beneficial to strengthening the biological activity and the electron utilization capacity of the sulfate reducing bacteria.

Example 3

Effect of florfenicol concentration on sulfate reduction

The reduction of the sulfate depends on the sulfate reducing bacteria to transfer electrons on an electrode to an electron acceptor, namely the sulfate, and the florfenicol can be used as the electron acceptor as the sulfate, so that the florfenicol and the sulfate are in a competitive electron relationship. 0mg/L, 1mg/L, 3mg/L and 5mg/L florfenicol is added into the cathode solution, samples are taken every 6 hours and are detected by an ultraviolet spectrophotometer, and the influence of the florfenicol concentration on the reduction of sulfate by sulfate reducing bacteria is researched.

The results show (see FIGS. 2 and 3) that 5mg/L FLO inhibits sulfate-reducing bacteria, whereas 1mg/L and 3mg/L FLO promotes sulfate-reducing bacteria, compared to the case where FLO was not added. Before FLO is added, the reduction efficiency of sulfate reducing bacteria to sulfate with the initial concentration of 400mg/L within 36h is 96 percent; after 1mg/L of FLO is added, the reduction efficiency of sulfate reducing bacteria to sulfate with the initial concentration of 400mg/L within 36h is 93 percent, which is not much different from the reduction efficiency before the addition, but the reduction rate of the sulfate in the presence of 1mg/L of FLO is always higher than that without the addition of FLO; the FLO concentration is increased to 3mg/L, and the reduction efficiency of the sulfate is greatly reduced to 78% in 36 hours, but the reduction rate of the sulfate is not much different from that of the sulfate without the FLO; when the FLO concentration is further increased to 5mg/L, the reduction efficiency of sulfate decreases to 66% in 36 hours, and the sulfate reduction rate is relatively low. The main reason is that the activity of sulfate reducing bacteria is reduced by high-concentration FLO, and florfenicol competes electrons with sulfate and plays a certain role in inhibiting the reduction of the sulfate. In conclusion, when the concentration of florfenicol is low, the efficiency of reducing sulfate by sulfate reducing bacteria is not inhibited.

Example 4

Effect of florfenicol concentration on sulfide production

The sulfide is generated because sulfate reducing bacteria reduce sulfate to obtain 8 electrons, sulfur is converted from positive hexavalent valence to negative divalent valence, but the sulfide is extremely unstable and is more easy to lose electrons to become elemental sulfur. 0mg/L, 1mg/L, 3mg/L and 5mg/L of florfenicol are added into the cathode solution, and the influence of the concentration of the florfenicol on the conversion of sulfide is researched.

The results show (see fig. 4 and 5) that FLO can promote electron loss of the negative divalent sulfur, and the higher the concentration of FLO is, the stronger the conversion promotion effect on the negative divalent sulfur is. Before addition of FLO; about 3.66mg/L of divalent sulfur can be generated in the solution within 6 hours; after 1mg/L of FLO is added, about 3.71mg/L of divalent sulfur can be generated in the solution within 6 hours, the difference between the amount of sulfur generated before the addition is not large, and the generation rates of the divalent sulfur and the sulfur are basically the same; the FLO concentration is increased to 3mg/L, and the generation amount of the bivalent sulfur in 6 hours is reduced to 1.44 mg/L; when the FLO concentration is continuously increased to 5mg/L, the generation amount of the divalent sulfur in 6 hours is 0.95mg/L, and after the FLO concentration is increased from 1mg/L to 3mg/L and 5mg/L, the generation rate of the divalent sulfur is also greatly reduced. This is mainly because FLO needs electrons during the reduction process, and besides the electrons provided by sulfate-reducing bacteria, can also obtain electrons from the negative sulfur which has been transformed from sulfate to be extremely unstable, so that the negative sulfur loses electrons to become elemental sulfur. In summary, the higher the florfenicol concentration, the less amount of negative divalent sulfur is produced.

Example 5

Influence of different concentrations of sulfate on florfenicol removal efficiency

In order to examine the reduction and removal efficiency of florfenicol by sulfate reducing bacteria under the condition of sulfate with different concentrations, the concentration of the florfenicol in reaction liquid with different degradation time is measured by high performance liquid chromatography (HPLC-UV), and the residual ratio (C/C0) of the florfenicol is calculated. Samples taken every 1h within 6 hours before the reactor was operated were taken as the study objects, i.e. reactor solutions of 0h, 1h, 2h, 3h, 4h, 5h, 6 h.

The results show (see FIG. 4) that the reduction rate of florfenicol is relatively fast at an initial florfenicol concentration of 5mg/L, with no sulfate and a sulfate concentration of 400 mg/L. Although the removal efficiency of the florfenicol within 6 hours can basically reach 100% under different sulfate concentration gradients, the reduction efficiency of the florfenicol within the first 3 hours under the conditions of high-concentration sulfate concentration and no sulfate is obviously higher, which indicates that the florfenicol is used as a unique electron acceptor to more efficiently absorb the electrons of the electrode to reduce the florfenicol without the sulfate, and the existence of the high-concentration sulfate can enhance the activity of sulfate reducing bacteria, efficiently utilize the electrons on the electrode and promote the reduction efficiency of the florfenicol.

Example 6

Effect of sulfate reducing bacteria on florfenicol removal pathway

Florfenicol can continuously exist in the form of various byproducts after being reduced by a BES system, and products with different structures and characteristics can have different toxic effects to generate different influences on a receiving water body, so that degradation intermediates of florfenicol are identified and the degradation intermediates are clear

The toxicity of the product is of great significance. And (3) identifying an intermediate product generated by the florfenicol in the reaction process with and without the sulfate reducing bacteria by adopting a liquid chromatography-mass spectrometry (HPLC-MS) technology.

The results show (see fig. 7 and 8 below), that 13 degradation intermediate structures of florfenicol are identified in total in the presence of sulfate reducing bacteria, and that 8 degradation intermediate structures of florfenicol are identified in total in the absence of sulfate reducing bacteria, and each degradation product is named according to the "mass-to-charge ratio of P + product ions (m/z)". As shown in FIG. 7, the degradation pathway of bioelectrochemically reduced florfenicol in the presence of sulfate-reducing bacteria is more diversified, and more simple molecules are produced.

The invention realizes the simultaneous removal of sulfate and florfenicol in water by utilizing the autotrophic biological cathode of the photoelectric coupling microbial electrolysis system, has short treatment period and good treatment effect, is improved on the basis of a photoelectric chemical battery, adds microbes to the cathode and builds the photoelectric coupling microbial electrolysis system. The combination of photoanode electrogenesis and microbial degradation technology can effectively remove sulfate and florfenicol in water, and reduce the biological toxicity of the system. The method has the advantages of short treatment period and good treatment effect, and the removal rate of sulfate is more than 80 percent, and the removal rate of florfenicol is more than 90 percent.

The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all simple modifications, equivalent changes and modifications made by the present specification, or directly/indirectly applied to other related technical fields, within the spirit of the present invention, are included in the scope of the present invention.

Claims

1. A process for simultaneously removing sulfate and florfenicol from water comprising the steps of:

(2) adding the bacterial liquid obtained in the step (1) and a sulfate substrate into a cathode chamber of a photoelectric coupling microbial reactor, wherein anolyte of the photoelectric coupling microbial reactor is a sulfate solution of 5 g/L;

2. The method according to claim 1, wherein in the step (2), the ratio of the bacterial liquid to the sulfate substrate is 1: 1.

3. The method of claim 1, wherein in step (2), the applied voltage of the photocoupler microbial reactor is 1.2V; in the step (3), the intensity of the ultraviolet light source is 13mW/cm²The reaction time for performing the photoanode power generation is 36 hours.

4. The method according to claim 1, characterized in that said step (1) comprises in particular:

the anaerobic bottle was placed in a constant temperature shaker.

5. The method according to claim 4, wherein the conditions of the constant temperature oscillator are 30 ℃ and 180 r/min.

6. The method according to claim 4, wherein the acclimated sulfate-reducing bacteria and the sulfate substrate are inoculated at a ratio of 1:10 in step 1), and the aeration time in step 2) is 5 min.

7. The method of claim 1, wherein in step (2), the photocoupling microbial reactor is set up by the following steps:

8. The method of claim 7, wherein in step (c), the reaction temperature is 150 ℃ and the reaction time is 5 hours.

9. The method of claim 7, wherein in step (d), the carbon brushes are 16 strands, 4cm long and 3.5cm wide.

10. The method according to claim 6, wherein in the step (e), the heat treatment condition is 450 ℃ for 30 min.