A method for rapid removal of antibiotics from water

Abstract

The present application belongs to the technical field of water treatment, and particularly relates to a method for rapidly removing antibiotics in wastewater. The present application controls the types and concentrations of free radicals generated by vacuum ultraviolet (VUV) photolysis by adjusting the concentration of dissolved oxygen in water, and realizes step-by-step selective removal of various antibiotics in water by relying on the oxidation-reduction effect of different free radicals. The method provided by the present application can achieve a removal rate of 98% and a mineralization rate of 86% for the parent of antibiotics in wastewater. The method does not add any chemicals, catalysts or other substances, and only by adjusting the concentration of oxygen in the system, the accurate step-by-step controllable removal of the oxidation-reduction of various antibiotics is realized, the evolution of bacterial drug resistance is controlled at the source, and the method has the technical advantages of green and efficient, simple operation and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of wastewater treatment, and particularly relates to a method for rapidly removing antibiotics in wastewater. BACKGROUND

[0002] Antibiotics are a kind of secondary metabolites with anti-pathogen or other activities produced by microorganisms (including bacteria, fungi and actinomycetes) or higher plants and animals in the life process, which can interfere with the development function of other living cells. The clinically commonly used antibiotics are extracts in microbial culture solution and compounds synthesized or semi-synthesized by chemical methods. However, in the process of human disease treatment, livestock and poultry breeding and aquaculture, there is a phenomenon of antibiotic abuse, and the antibiotic wastewater generated in these processes has not been effectively treated, thereby causing serious antibiotic pollution in environmental water bodies. At present, antibiotics have been detected in various environmental water bodies, such as lakes, rivers, beaches, near-shore waters and groundwater, with the highest concentration reaching mg / L level, which will inevitably bring certain survival pressure to the microorganisms in the water bodies. In addition, the global health and safety problem of antibiotic-driven bacterial resistance has posed a serious threat to human health. Therefore, the removal of antibiotics in wastewater is of great significance to the health of human beings and the entire ecological system.

[0003] The water treatment process actually adopted at present has limited treatment efficiency on antibiotics, and in addition to the difficulty in biodegradation of antibiotics, it has become the focus of attention of researchers. In recent years, various methods for removing antibiotics in water have been developed, which can be divided into three categories according to their main mechanisms, namely physical method, biological method and chemical method. The common physical methods are adsorption and membrane filtration, etc. These methods only transfer the antibiotics to the medium, and the adsorbent and filtration material can become secondary pollutants, which still have environmental risks. Therefore, the current research often combines physical methods with other technologies to achieve the fundamental removal of antibiotics; the biological method for treating antibiotic wastewater also has certain effect, and by adjusting the variable parameters of the constructed wetland, the removal effect of the constructed wetland on sulfonamide antibiotics is strengthened, but with the gradual deterioration of the global health disaster of bacterial resistance, the seriousness of antibiotic-driven bacterial resistance gene evolution is realized, and the view that biological method for treating antibiotics may increase the risk of resistance is put forward; therefore, the chemical method for removing antibiotics is the current research hotspot, especially photoelectrocatalysis, which has good removal effect on various antibiotics, such as ultraviolet (UV) / persulfate, UV / sulfite, but most of the photoelectrocatalytic processes depend on catalysts and other activators, which not only increase the cost of antibiotic treatment, but also inevitably cause secondary pollution to the environment, so a green and efficient antibiotic removal technology is urgently needed to avoid the occurrence of the above problems.

[0004] UV-based redox technology has been widely studied. UV light can be divided into four wave bands, namely UV-A (315-380 nm), UV-B (280-315 nm), UV-C (200-280 nm), and vacuum ultraviolet (VUV) (150-200 nm). Chinese invention patent document CN202111152435.4 discloses a method for removing antibiotics and resistance genes in wastewater using ultraviolet / peroxyacetic acid. The main steps are to add peroxyacetic acid to the wastewater, stir uniformly, and then irradiate with ultraviolet light, which can simultaneously remove antibiotics and resistance genes in the wastewater. This process has a certain treatment effect on antibiotics, but the addition process of exogenous substances has problems such as secondary pollution and high cost.

[0005] According to whether the antibiotic contains a halogen substituent, it can be divided into two categories: halogenated antibiotics and non-halogenated antibiotics. Among them, the carbon-halogen bond (C-X) structure in halogenated antibiotics is the main antibacterial active group of this type of antibiotic, and its bond energy is often high, especially the C-F bond, which is difficult to destroy halogenated antibiotics simply by advanced oxidation. However, reduction radicals such as hydrated electrons (e aq - ) and hydrogen radicals H· can more efficiently achieve selective dehalogenation of halogenated antibiotics. The dissolved oxygen concentration in the reaction system can play a decisive role in affecting the main mechanism of VUV photolysis. When the dissolved oxygen concentration in the reaction solution is at a low level, the system is mainly e aq - , H·, and other reducing radicals play a role, and VUV photolysis of pollutants tends to be a high-level reduction process; while when the dissolved oxygen in the reaction solution is more sufficient, VUV photolysis of pollutants tends to be a high-level oxidation process, because e aq - , H·, and other reducing radicals react with oxygen to generate secondary oxidative radicals (such as singlet oxygen and superoxide anion), and make the HO·, ozone and other oxidative species generated by photolysis of water more stable. SUMMARY

[0006] In order to solve the above problems, the application provides a method for destroying the structure of antibiotics by direct photolysis and indirect photolysis of pollutants using 185 and 254 nm dual-wavelength ultraviolet light emitted by a vacuum ultraviolet lamp, preferentially using a reducing system formed under low dissolved oxygen conditions to realize selective dehalogenation of halogenated antibiotics by VUV, and then converting the VUV photolysis into a high-level oxidation system by increasing the dissolved oxygen concentration of the system, thereby realizing further mineralization of the intermediate of the halogenated antibiotic after reduction in the previous step, and achieving the purpose of oxidizing and removing other non-halogenated antibiotics. The method does not add any chemicals, catalysts and other substances, and only by adjusting the oxygen concentration in the system can the accurate step-by-step controllable removal of various antibiotics be realized, thereby controlling the evolution of bacterial drug resistance at the source, and the method has the technical advantages of being green, efficient and easy to operate.

[0007] In one aspect, the application provides a method for quickly removing antibiotics in wastewater, comprising the following steps: adjusting the dissolved oxygen concentration in the wastewater, and then performing a photolysis reaction under vacuum ultraviolet; the vacuum ultraviolet can include two wavelengths of ultraviolet light; the two wavelengths of ultraviolet light are 185 nm and 254 nm.

[0008] Specifically, the antibiotics are non-halogenated antibiotics, and the removal method is to increase the dissolved oxygen concentration for photolysis.

[0009] Specifically, the antibiotics are halogenated antibiotics, and the removal method is to first reduce the dissolved oxygen concentration for photolysis, and then increase the dissolved oxygen concentration for photolysis.

[0010] Specifically, the antibiotics are non-halogenated antibiotics and halogenated antibiotics, and the removal method is to first reduce the dissolved oxygen concentration for photolysis, and then increase the dissolved oxygen concentration for photolysis.

[0011] Further specifically, the aforementioned photolysis with increased dissolved oxygen concentration is an oxidation reaction, and the photolysis with reduced dissolved oxygen concentration is a reduction reaction.

[0012] Further specifically, the aforementioned reduction of the dissolved oxygen concentration is not higher than 1 mg / L.

[0013] Preferably, the low dissolved oxygen concentration is 1 mg / L.

[0014] Further specifically, the aforementioned increase of the dissolved oxygen concentration is not less than 20 mg / L.

[0015] Preferably, the increase of the dissolved oxygen concentration is 20 mg / L.

[0016] Specifically, the aforementioned photolysis time with reduced dissolved oxygen concentration is not less than 0.5 min.

[0017] Further specifically, the aforementioned light irradiation time for reducing the dissolved oxygen concentration can be appropriately adjusted according to the concentration of the antibiotic in the water.

[0018] Specifically, the aforementioned light irradiation time for increasing the dissolved oxygen concentration is not less than 2 min.

[0019] Further specifically, the aforementioned light irradiation time for increasing the dissolved oxygen concentration can be appropriately adjusted according to the concentration of the antibiotic in the water.

[0020] Specifically, the aforementioned non-halogenated antibiotic can be tetracycline.

[0021] Specifically, the aforementioned halogenated antibiotic can be one or more of florfenicol or enrofloxacin.

[0022] Specifically, the aforementioned vacuum ultraviolet device is a vacuum ultraviolet reactor, which is internally provided with seven vacuum ultraviolet light sources in parallel.

[0023] Specifically, the aforementioned vacuum ultraviolet light source includes a low-pressure mercury lamp and a high-purity quartz cover, and can emit two wavelengths of ultraviolet light.

[0024] Specifically, six of the aforementioned vacuum ultraviolet light sources are arranged at the vertices of an inscribed hexagon, the distance between the inner wall of the reactor and the outer quartz sleeve of the ultraviolet lamp is controlled to be within 5 cm, and the remaining one is arranged at the center position.

[0025] The technical effects achieved by the present application are as follows:

[0026] (1) The removal rate and mineralization rate of the antibiotic mother body in the wastewater can be as high as 98% and 86%, respectively.

[0027] (2) Without adding any chemical agents, catalysts and other substances, the evolution of bacterial drug resistance is controlled at the source.

[0028] (3) The removal speed is fast, and the operation is simple. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The VUV reactor structure schematic diagram and lamp source distribution diagram used in the method for rapidly removing antibiotics in water provided by the present application are shown in the following figure. DETAILED DESCRIPTION

[0030] The present application will be further described in detail below in conjunction with specific embodiments, and the following examples are not used to limit the present application, but only to illustrate the present application. Unless otherwise specified, the experimental methods used in the following examples are generally carried out under conventional conditions. Unless otherwise specified, the materials, reagents, etc. used in the following examples can be obtained from commercial channels.

[0031] Example 1

[0032] The VUV reactor is cylindrical, and has seven vacuum ultraviolet light sources arranged in parallel inside. Each ultraviolet light source includes a low-pressure mercury lamp and a high-purity quartz cover, and can emit ultraviolet light of two wavelengths, 185 nm and 254 nm. Of the seven ultraviolet light sources arranged in parallel inside the VUV reactor, six are arranged at the six vertices of an inscribed hexagon, and the distance between the inner wall of the reactor and the outer quartz sleeve of the ultraviolet lamp is controlled to be within 5 cm. The remaining one is arranged at the center position to maximize the utilization rate of photons.

[0033] The method for quickly removing antibiotics from water described in the embodiment is performed according to the following steps:

[0034] (1) The antibiotic composition and the concentration of each antibiotic are analyzed. The results show that there are two halogenated antibiotics and one non-halogenated antibiotic in the wastewater: florfenicol, enrofloxacin, and tetracycline, with concentrations of 5.07 mg / L, 2.98 mg / L, and 2.93 mg / L, respectively.

[0035] (2) The wastewater containing antibiotics to be treated is transferred to a vacuum ultraviolet (VUV) reactor.

[0036] (3) The nitrogen valve is opened to pre-aerate the wastewater with nitrogen, and the dissolved oxygen concentration in the wastewater is reduced to 1 mg / L. Then the ultraviolet lamp is turned on and the timing starts. After 3 minutes, the ultraviolet lamp is turned off, and the nitrogen gas is stopped, completing the reduction and dehalogenation removal of halogenated antibiotics.

[0037] (4) The oxygen valve is opened to increase the dissolved oxygen concentration in the wastewater to 20 mg / L. Then the ultraviolet lamp is turned on again and the timing starts. The light irradiation reaction continues for 4 minutes. Then the light irradiation and oxygen supply are stopped, completing the oxidation removal of dehalogenated halogenated antibiotics and non-halogenated antibiotics in the water body.

[0038] The results are shown in Table 1. After treatment, the degradation rate of florfenicol was 99.86%, the defluorination rate was 85.45%, and the dechlorination rate was 95.62%; the degradation rate of enrofloxacin was 99.66%, the defluorination rate was 82.52%; the degradation rate of tetracycline was 98.63%; and the total mineralization rate of the system was 86.77% (total mineralization rate = (total organic carbon before treatment - total organic carbon after treatment) / total organic carbon before treatment x 100%).

[0039] When the wastewater does not contain halogenated antibiotics, step (3) can be omitted.

[0040] Table 1: Measurement and evaluation indicators of the water body in Example 1

[0041]

[0042] Example 2

[0043] The method for quickly removing antibiotics in water according to the embodiment is performed according to the following steps:

[0044] (1) The antibiotic composition and the concentration of each antibiotic are analyzed, and the results show that only one non-halogenated antibiotic, tetracycline, exists in the wastewater, and the concentration is 3.11 mg / L.

[0045] (2) The antibiotic-containing wastewater to be treated is transferred to a vacuum ultraviolet (VUV) reactor.

[0046] (3) The oxygen valve is opened to increase the dissolved oxygen concentration in the wastewater to 20 mg / L, then the ultraviolet lamp is restarted and timing is started, the light irradiation reaction is continued for 2 min, the light irradiation and oxygen supply are stopped, and the oxidation removal of the non-halogenated antibiotic in the water body is completed.

[0047] The results are shown in Table 2. The degradation rate of tetracycline in the treated water body is 99.86%, and the total mineralization rate of the system is 89.73%.

[0048] Table 2 Measurement and evaluation indexes of the water body in Example 2

[0049] Indicators Tetracycline Total organic carbon Before treatment 3.11 mg / L 1.85 mg / L After treatment 4.35 μg / L 0.19 mg / L

[0050] Comparative Example 1

[0051] Compared with Example 1, the dissolved oxygen concentration after pre-nitrogen supply is higher than 1 mg / L, and the others are the same as Example 1, which are as follows:

[0052] A method for quickly removing antibiotics in water is performed according to the following steps:

[0053] (1) The antibiotic composition and the concentration of each antibiotic are analyzed, and the results show that two halogenated antibiotics and one non-halogenated antibiotic exist in the wastewater: florfenicol, enrofloxacin, and tetracycline, with concentrations of 5.07 mg / L, 2.98 mg / L, and 2.93 mg / L, respectively.

[0054] (2) The antibiotic-containing wastewater to be treated is transferred to a vacuum ultraviolet (VUV) reactor.

[0055] (3) The nitrogen valve is opened to pre-aerate the wastewater by nitrogen supply, the dissolved oxygen concentration in the wastewater is reduced to 5 mg / L, then the ultraviolet lamp is turned on and timing is started, nitrogen supply is stopped after 3 min, and the ultraviolet lamp is turned off, and the reduction and dehalogen removal of halogenated antibiotics are completed.

[0056] (4) The oxygen valve is opened to increase the dissolved oxygen concentration in the wastewater to 20 mg / L, then the ultraviolet lamp is restarted and timing is started, the light irradiation reaction is continued for 4 min, the light irradiation and oxygen supply are stopped, and the oxidation removal of the dehalogenated halogenated antibiotic and the non-halogenated antibiotic in the water body is completed.

[0057] The results are shown in Table 3. The degradation rate of florfenicol is 78.30%, the defluorination rate is 63.18%, and the dechlorination rate is 73.60%; the degradation rate of enrofloxacin is 80.20%, the defluorination rate is 57.13%; the degradation rate of tetracycline is 97.61%; and the total mineralization rate of the system is 80.78%.

[0058] Table 3. Measurement and evaluation indexes of water body in Comparative Example 1

[0059]

[0060] Comparative Example 2

[0061] In Comparative Example 2, the oxygen valve is opened to increase the dissolved oxygen concentration in the wastewater to less than 20 mg / L, and the other conditions are the same as in Example 1. The specific conditions are as follows:

[0062] A method for rapidly removing antibiotics in water is carried out according to the following steps:

[0063] (1) Analyze the composition of the antibiotics and the concentration of each antibiotic. The results show that there are two halogenated antibiotics and one non-halogenated antibiotic in the wastewater: florfenicol, enrofloxacin and tetracycline, with concentrations of 5.07 mg / L, 2.98 mg / L and 2.93 mg / L, respectively.

[0064] (2) Transfer the wastewater containing antibiotics to be treated into a vacuum ultraviolet (VUV) reactor.

[0065] (3) Open the nitrogen valve to pre-aerate the wastewater by passing nitrogen gas, reduce the dissolved oxygen concentration in the wastewater to 1 mg / L, then open the ultraviolet lamp and start timing, stop passing nitrogen gas after 3 minutes, and close the ultraviolet lamp, to complete the reduction and dehalogen removal of halogenated antibiotics.

[0066] (4) Open the oxygen valve to increase the dissolved oxygen concentration in the wastewater to 10 mg / L, then reopen the ultraviolet lamp and start timing, continue the light irradiation for 4 minutes, stop the light irradiation and oxygen passing, to complete the oxidation removal of halogenated antibiotics and non-halogenated antibiotics in the water body.

[0067] The results are shown in Table 4. The degradation rate of florfenicol is 97.24%, the defluorination rate is 81.76%, and the dechlorination rate is 90.50%; the degradation rate of enrofloxacin is 95.97%, the defluorination rate is 76.17%; the degradation rate of tetracycline is 88.40%; and the total mineralization rate of the system is 51.50%.

[0068] Table 4. Measurement and evaluation indexes of water body in Comparative Example 2

[0069]

[0070] From the data results of the case 1-2, it can be seen that the method has very ideal pollutant removal effect and mineralization effect on florfenicol, enrofloxacin and tetracycline. Compared with the results of comparative examples 1 and 2, the results of the case 1 can illustrate that the dissolved oxygen concentration plays a crucial role in the removal process. When the dissolved oxygen concentration in the pre-exposure nitrogen stage is not reduced to 1 mg / L, the efficiency of the reduction stage is decreased, the degradation of florfenicol and enrofloxacin is inhibited, and the dehalogenization efficiency is also obviously decreased, which also interferes with the mineralization performance of the oxidation stage. After the completion of the reduction stage reaction, if the oxygen concentration in the water is not increased to 20 mg / L, the degradation rate of the non-halogenated antibiotic is decreased, and the mineralization rate of the whole system is also obviously decreased, which shows that there are still a large amount of by-products produced in the antibiotic degradation process in the water body, which may bring potential threat to the environment. Therefore, the dissolved oxygen concentration in the water in different treatment stages should be strictly controlled during the use of the method.

[0071] Comparative example 3

[0072] Compared with the case 1, the wastewater is only subjected to vacuum ultraviolet irradiation or dissolved oxygen adjustment, and the others are the same as the case 1, which are as follows:

[0073] A method for quickly removing antibiotics in water is carried out according to the following steps:

[0074] (1) Analyze the composition and concentration of the antibiotics, and the results show that there are two halogenated antibiotics and one non-halogenated antibiotic in the wastewater: florfenicol, enrofloxacin and tetracycline exist in the wastewater, and the concentrations are 5.07 mg / L, 2.98 mg / L and 2.93 mg / L, respectively.

[0075] (2) The wastewater containing antibiotics to be treated is transferred to a vacuum ultraviolet (VUV) reactor.

[0076] (3) Open the nitrogen valve to reduce the dissolved oxygen in the system to 1 mg / L, and start timing, only nitrogen for 3 min or only ultraviolet lamp for 3 min.

[0077] (4) Open the oxygen valve to increase the dissolved oxygen concentration in the wastewater to 10 mg / L, and start timing, only oxygen for 4 min or only ultraviolet lamp for 4 min.

[0078] After only light treatment, it is determined that the degradation rate of florfenicol is 37.87%, the defluorination rate is 0%, and the dechlorination rate is 29.73%; the degradation rate of enrofloxacin is 25.50%, the defluorination rate is 0%; the degradation rate of tetracycline is 44.37%; and the total mineralization rate of the system is 25.57%.

[0079] The specific design and results are shown in Table 5.

[0080] Table 5 Measurement and evaluation indexes of the water body in comparative example 3

[0081]

[0082] As can be seen from Table 5, if only vacuum ultraviolet irradiation is performed without controlling the dissolved oxygen of the reaction solution, this measure cannot highlight the reduction performance of the reaction process. Due to insufficient content of the reducing free radicals in the system, a large amount of C-F and C-Cl cannot be broken, so that the dehalogenation effect is significantly lower than that of Example 1. If only the adjustment of the dissolved oxygen is performed without the VUV light irradiation process, it is found that florfenicol, enrofloxacin and tetracycline are all not degraded, and the dehalogenation rate and the mineralization rate are close to 0. It can be seen that pure dissolved oxygen control cannot achieve the removal of antibiotics in wastewater, and VUV photolysis plays a crucial role in the process.

[0083] Comparative Example 4

[0084] Compared with Example 1, the ultraviolet wavelength is replaced by a single wavelength of 254 nm under the same power radiation, and the others are the same as Example 1, as follows:

[0085] (1) The antibiotic composition and the concentration of each antibiotic were analyzed, and the results showed that there were two halogenated antibiotics and one non-halogenated antibiotic in the wastewater: florfenicol, enrofloxacin and tetracycline, with concentrations of 5.07 mg / L, 2.98 mg / L and 2.93 mg / L, respectively.

[0086] (2) The antibiotic-containing wastewater to be treated was transferred to a 254 nm vacuum ultraviolet (VUV) reactor.

[0087] (3) The nitrogen valve was opened to pre-aerate the wastewater, and the dissolved oxygen concentration in the wastewater was reduced to 1 mg / L. Then the ultraviolet lamp was turned on to start timing, and after 3 min, the ultraviolet lamp was turned off and the nitrogen gas was stopped, to complete the reduction and dehalogenation removal of halogenated antibiotics.

[0088] (4) The oxygen valve was opened to increase the dissolved oxygen concentration in the wastewater to 20 mg / L, and then the ultraviolet lamp was turned on again to start timing, and the light irradiation was continued for 4 min. The light irradiation and oxygen supply were stopped, to complete the oxidation removal of the dehalogenated halogenated antibiotics and non-halogenated antibiotics in the water body.

[0089] The results are shown in Table 6. After treatment, the degradation rate of florfenicol was 60.36%, the defluorination rate was 3.72%, the dechlorination rate was 13.92%; the degradation rate of enrofloxacin was 29.19%, the defluorination rate was 0%; the degradation rate of tetracycline was 41.98%; and the total mineralization rate of the system was 6.00%.

[0090] Table 6 Measurement and evaluation indexes of the water body in Comparative Example 4

[0091]

[0092] The results showed that the single wavelength irradiation had some effect on the antibiotics, but the dehalogenation efficiency was less than 20%, and the functional groups of florfenicol and enrofloxacin could not be destroyed, which would make the antibiotics still have some antibacterial activity. The performance of the selected radiation wavelengths (185 nm and 254 nm) for photolyzing antibiotics was significantly better than that of the single wavelength (254 nm).

Claims

1. A method for rapid removal of antibiotics from wastewater, characterized by, The method comprises the following steps: After adjusting the dissolved oxygen concentration in the wastewater, light irradiation is performed under vacuum ultraviolet; the vacuum ultraviolet comprises two wavelengths of ultraviolet light; the two wavelengths of ultraviolet light are 185 nm and 254 nm; The antibiotic is a halogenated antibiotic, and the removal method is: first, reducing the dissolved oxygen concentration for light irradiation, and then, increasing the dissolved oxygen concentration for light irradiation; The antibiotic is a non-halogenated antibiotic and a halogenated antibiotic, and the removal method is: first, reducing the dissolved oxygen concentration for light irradiation, and then, increasing the dissolved oxygen concentration for light irradiation; The reduced dissolved oxygen concentration is not higher than 1 mg / L. The increased dissolved oxygen concentration is not lower than 20 mg / L.

2. The method of claim 1, wherein, The light irradiation time for reducing the dissolved oxygen concentration is not less than 0.5 min.

3. The method of claim 1, wherein, The light irradiation time for increasing the dissolved oxygen concentration is not less than 2 min.

4. The method according to any one of claims 1 to 3, characterized in that, The non-halogenated antibiotic is tetracycline.

5. The method according to any one of claims 1 to 3, characterized in that, The halogenated antibiotic is one or more of florfenicol or enrofloxacin.

Images