Method for co-metabolic degradation of antibiotics by ammonia-oxidizing sludge

Abstract

The application discloses a method for strengthening ammonia-oxidizing sludge co-metabolic degradation of antibiotics, and belongs to the technical field of sewage treatment. The method enriches ammonia-oxidizing sludge first, uses artificially synthesized sewage as influent of the ammonia-oxidizing sludge enrichment reactor, adjusts the pH to be acidic to operate the reactor, and processes sulfamethoxazole with different concentrations in the influent in stages, so that the ammonia-oxidizing sludge co-metabolic degradation of sulfamethoxazole is strengthened, and under long-term operation conditions, the ammonia nitrogen removal rate is not significantly inhibited. The method can not only remove ammonia nitrogen in sewage, but also efficiently and stably degrade antibiotics, so that the spread and harm of pathogens in nature can be reduced, and the biological diversity and stability of the ecological system are protected.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for co-metabolic degradation of antibiotics by enhanced ammonia-oxidizing sludge, belonging to the technical field of wastewater treatment. BACKGROUND

[0002] Antibiotics are one of the most effective drugs for treating infectious diseases in humans and livestock. Antibiotics entering the human and animal body cannot be completely absorbed and metabolized, and most of them are directly discharged into the environment or enter the wastewater treatment plant in the form of original or active metabolites through feces and urine. However, the current wastewater treatment process cannot completely degrade antibiotics, resulting in the continuous accumulation of antibiotics in the environment.

[0003] Antibiotics have great harm to the human body, including interfering with intestinal microorganisms, affecting the immune system, and causing various adverse reactions. The abuse of antibiotics in the livestock breeding industry can harm animal health, reduce animal immunity and disease resistance, and also remain in meat, milk, eggs and other products, threatening human food safety and physical health. In addition, antibiotics as antibacterial drugs have certain biological toxicity, and the residual antibiotics in the environment can kill microorganisms without drug resistance, select drug-resistant bacteria, change the local microbial community, and have an impact on higher organisms through the food chain, thereby disrupting the local ecological balance. Among them, sulfonamide antibiotics, such as sulfadimoxazole, sulfadiazine, and sulfamethoxazole, are widely used in the treatment of diseases in humans and animals, especially in the livestock breeding industry, which has led to the widespread use of sulfonamide antibiotics in the human living environment. Literature has shown that the content of sulfonamide antibiotics in wastewater treatment plants is among the top three. Wastewater treatment plants have become one of the main collection sites for antibiotics, and as the use of antibiotics continues to increase, the concentration of antibiotics in wastewater treatment plant influent and effluent also shows a gradually increasing trend.

[0004] Existing antibiotic degradation technologies mainly include adsorption, advanced oxidation, membrane separation, constructed wetland, and biological methods. Biological methods are one of the most commonly used technologies, which has low operating cost and is relatively economical. Among them, activated sludge method is the most widely used. However, the degradation effect of traditional activated sludge method on antibiotics is relatively unstable, is greatly affected by external environmental conditions, and cannot inhibit the spread of drug-resistant bacteria.

[0005] In recent years, more and more studies have shown that the co-metabolism of ammonia-oxidizing bacteria (AOB) is one of the effective ways to enhance the degradation of new pollutants such as antibiotics. Co-metabolism is the process in which microorganisms produce non-specific enzymes to decompose and transform non-growth substrates such as antibiotics when the growth substrate is present and can provide sufficient carbon source or energy. This is because AOB has a non-specific functional enzyme, ammonia monooxygenase (AMO). AMO has a wide range of substrates and can co-metabolize and degrade new pollutants such as antibiotics while oxidizing ammonia. In previous studies, the main research direction is the relationship between antibiotic degradation rate and ammonia oxidation rate, identification of degradation products, etc., which is conducive to further understanding the degradation pathway of antibiotics. However, the above studies are only limited to laboratory conditions and do not consider the appropriate conditions in actual wastewater treatment plants. In actual wastewater treatment plants, the abundance of AOB is often not high, and AOB is an autotrophic bacterium with a long generation cycle and slow proliferation, which also limits its degradation of new pollutants such as antibiotics. Therefore, it is necessary to further enhance the co-metabolic degradation of AOB to achieve the purpose of efficient and stable degradation of antibiotics.

[0006] In addition, the biological killing / inhibition effect of free nitrous acid (FNA) can be applied to multiple units of municipal wastewater systems to improve the overall management level of the wastewater system. However, in order to produce the required concentration of FNA, it is currently necessary to add nitrite and acid at the same time, which further increases the chemical cost. The ammonia oxidation process, as the rate-limiting step of nitrification, involves the biochemical process in which microorganisms oxidize ammonia (NH3) to nitrite (NO2 - ) and the ammonia oxidation process is mainly driven by AOB, ammonia-oxidizing archaea (AOA), and Comammox, and FNA has a certain inhibitory effect on nitrite-oxidizing bacteria (NOB).

[0007] In summary, how to effectively utilize the co-metabolic degradation of AOB and the non-biological degradation of FNA to efficiently and stably degrade antibiotics in wastewater is crucial for the treatment of wastewater containing antibiotics. SUMMARY

[0008] In order to solve one or more of the above problems, the present application enriches ammonia-oxidizing sludge, uses synthetic wastewater as the influent of the ammonia-oxidizing sludge reactor for experiments, adjusts the pH of the reaction S2-S4 stage to acidic conditions, operates the reactor (R1), and adds sulfamethoxazole (SMX) with a final concentration of 1 mg / L and 5 mg / L in the influent at the S3 and S4 stages, respectively, to fully utilize the non-biological degradation of FNA and the co-metabolic degradation of AOB, and efficiently and stably degrade antibiotics in wastewater. In addition, the present application can also effectively remove ammonia nitrogen in wastewater, greatly improving the efficiency of wastewater treatment.

[0009] The first object of the present application is to provide a method for degrading antibiotics in sewage, comprising the following steps:

[0010] (1) Start-up phase:

[0011] Enriching ammonia-oxidizing sludge in the reactor;

[0012] Adding nitrogen source and phosphorus source to the influent of the reactor, controlling pH to be 7.5-8, and maintaining for 70-80 d;

[0013] (2) Formal treatment:

[0014] Setting the operation cycle of the reactor and dividing the whole reaction into four phases:

[0015] In S1 phase, the influent is sewage, and the operation is maintained under alkaline conditions for 10-15 d;

[0016] In S2 phase, the influent is sewage, and the operation is adjusted under acidic conditions for 10-15 d;

[0017] In S3 phase, the influent is sewage containing antibiotics, and the operation is maintained for 30-40 d;

[0018] In S4 phase, the influent is sewage containing antibiotics, and the operation is maintained for 20-30 d.

[0019] In an embodiment, in step (1), the nitrogen source is NH4HCO3, and the concentration of the additional nitrogen source added to the influent is 2.5-2.85 g / L.

[0020] In an embodiment, in step (1), the phosphorus source is one or more of K2HPO4 and KH2PO4, and the concentration of the additional phosphorus source added to the influent is 0.06-0.07 g / L.

[0021] In an embodiment, in step (1), pH is controlled to be 7.5-8 by adding NaHCO3.

[0022] In an embodiment, in step (2), the alkaline condition in S1 phase is pH=7.5-8.

[0023] In an embodiment, in step (2), the acidic condition in S2 phase is pH=6-7.

[0024] In an embodiment, in step (2), the reactor is a SBR reactor, and the operation cycle of the SBR reactor is 4 cycles per day, each cycle being 360 min, including influent for 60 min, aeration for 260 min, sedimentation for 30 min, drainage for 5 min, and standing for 5 min; the drainage ratio is 25%.

[0025] In an embodiment, in step (2), the influent of S3 and S4 is wastewater containing antibiotics, and the antibiotics are one or more of sulfonamide antibiotics, macrolide antibiotics, tetracycline antibiotics, and polyamine antibiotics, preferably sulfonamide antibiotics, and further preferably sulfisoxazole.

[0026] In an embodiment, in step (2), the influent of S3 is wastewater containing antibiotics, and the concentration of the antibiotics in the influent is 0.5-1.5 mg / L.

[0027] In an embodiment, in step (2), the influent of S4 is wastewater containing antibiotics, and the concentration of the antibiotics in the influent is 4-6 mg / L.

[0028] In an embodiment, in step (2), the alkaline condition (pH = 7.5-8) of S1 is the most suitable condition for the growth of AOB.

[0029] In an embodiment, in step (2), the four stages are:

[0030] In S1, the concentration of SMX in the influent is 0 mg / L, the pH of the reactor is maintained at 7.5-8, and the operation is performed for 10-15 days;

[0031] In S2, the concentration of SMX in the influent is 0 mg / L, the pH is adjusted to 6-7, and the operation is performed for 10-15 days;

[0032] In S3, the concentration of SMX in the influent is 0.5-1.5 mg / L, and the operation is performed for 30-40 days;

[0033] In S4, the concentration of SMX in the influent is 4-6 mg / L, and the operation is performed for 20-30 days.

[0034] In an embodiment, in step (1), the enrichment of ammonia-oxidizing sludge comprises the following steps:

[0035] (1) The inoculated sludge is diluted with tap water and then added to the reactor;

[0036] (2) The reactor is operated as a working cycle in the order of influent, aeration, sedimentation, effluent, and stagnation by feeding artificial synthetic wastewater into the reactor; during the aeration process, the DO concentration is controlled to be 0.5-1 mg / L by using a rotor flowmeter;

[0037] When the ammonia nitrogen concentration of the reactor effluent is lower than 1 mg / L and stable operation is maintained for 5 days, the ammonia nitrogen concentration of the artificial synthetic sewage is increased by 100 mg / L, when the ammonia nitrogen concentration of the reactor effluent is again lower than 1 mg / L and stable operation is maintained for 5 days, the ammonia nitrogen concentration of the artificial synthetic sewage is again increased by 100 mg / L, and the process is repeated until the ammonia nitrogen concentration of the artificial synthetic sewage is increased from 100 mg / L to 500 mg / L;

[0038] (3) When the last working cycle is completed, the sludge in the reactor is the sludge enriched with AOB;

[0039] The reactor is a cylindrical sequencing batch reactor (SBR reactor), the outer layer of the reactor is provided with a heat preservation layer, and the bottom of the reactor is provided with an aeration disc.

[0040] In an embodiment, the sewage is artificial synthetic sewage, and the formula of the artificial synthetic sewage is: ammonia nitrogen concentration 100 mg / L-500 mg / L, KH2PO4 64 mg / L, K2HPO4 64 mg / L, NaHCO3 4 g / L, trace element liquid 2 mL / L, and pH value 7.8±0.2; wherein the composition of the trace element liquid is: ZnSO4·7H2O 0.55 g / L, MnCl2·4H2O 1.275 g / L, CoCl2 6H2O 0.4 g / L, CuSO4·5H2O 0.4 g / L, MgSO4·7H2O 44.4 g / L, FeCl3·6H2O 1.25 g / L, Na2MoO4·2H2O 0.05 g / L, CaCl2·2H2O 1.375 g / L, and MgSO4·7H2O 44.4 g / L.

[0041] In an embodiment, the method is achieved by adjusting the S2 stage to be an acidic pH condition to strengthen the co-metabolic effect of the ammonia oxidation sludge.

[0042] A second object of the present application is to provide the above-mentioned method for use in strengthening degradation of sewage containing antibiotics.

[0043] A third object of the present application is to provide the above-mentioned method for use in strengthening degradation of sewage containing ammonia nitrogen.

[0044] Advantages

[0045] (1) The present application adjusts the pH of S2-S4 stage to be acidic condition, and runs the reactor, which is recorded as R1, while the reactor R2 running with alkaline pH of S1-S4 stage is used for comparison. The SMX is added into the influent in S3 and S4 stages to make the concentration of 1 mg / L and 5 mg / L, respectively. It is found that the acidic pH condition can strengthen the co-metabolic degradation of SMX by ammonia-oxidizing sludge, and at the same time, the removal rate of NH3-N is not significantly inhibited under long-term running condition;

[0046] (2) The present application makes full use of the characteristics of ammonia-oxidizing bacteria that can co-metabolize biodegradation of antibiotics, and adjusts the pH of S2-S4 stage to be acidic. At the same time, nitrite is produced in the ammonia oxidation process, and free nitrous acid (FNA) can chemically degrade antibiotics. The present application not only has co-metabolic effect, but also has chemical degradation effect of FNA, which synergistically strengthens the degradation of antibiotics;

[0047] (3) The method of the present application not only can remove ammonia nitrogen in wastewater, but also can efficiently and stably degrade antibiotics, which can reduce the spread and harm of pathogens in nature, thereby protecting the biodiversity and stability of the ecosystem. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1 The degradation rate of sulfamethoxazole by the ammonia-oxidizing sludge-enriched reactor running under the alkaline pH condition of S1 stage and the acidic pH condition of S2-S4 stage in Example 1;

[0049] Figure 2 The degradation rate of sulfamethoxazole by the ammonia-oxidizing sludge-enriched reactor running under the alkaline pH condition of S1-S4 stage in Comparative Example 1;

[0050] Figure 3 The removal rate of ammonia nitrogen by the ammonia-oxidizing sludge-enriched reactors in Example 1 and Comparative Example 1;

[0051] Figure 4 The specific ammonia oxidation rate of the ammonia-oxidizing sludge-enriched reactors in Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0052] To make the purpose, technical scheme and advantages of the present application clearer, the embodiments of the present application will be further described in detail below with reference to the drawings.

[0053] Firstly, the related detection methods / calculating formulas, influent conditions and technical terms involved in the present application are introduced as follows:

[0054] 1. The test methods / calculating formulas involved in the following examples and comparative examples are as follows:

[0055] (1) Ammonia nitrogen concentration

[0056] Determination by Nessler's reagent spectrophotometry.

[0057] Ammonia nitrogen removal rate (%) = (influent ammonia nitrogen concentration - effluent ammonia nitrogen concentration) / influent ammonia nitrogen concentration x 100%

[0058] (2) Specific ammonia oxidation rate SAOR

[0059] The specific ammonia oxidation rate (SAOR) is obtained by calculating the ratio of ammonia oxidation rate (AOR) to mixed liquor volatile suspended solids concentration (MLVSS). The ammonia nitrogen concentration at each time interval is determined by taking water samples from the reactor every 10 minutes within 1 hour, and then the linear slope obtained by linear fitting is the AOR. The MLVSS is determined by gravimetric method.

[0060] (3) Sulfamethoxazole (SMX) concentration

[0061] Determination by high-performance liquid chromatography (HPLC). The HPLC chromatographic column is a C18 column (250 x 4.6 mm, 5 μm; Agilent Technologies, Germany), the mobile phase A is acetonitrile, the mobile phase B is 0.1% formic acid solution, the liquid phase flow rate is 1 mL / min, the column temperature is 30°C, the sample injection amount is 10 μL, and the detection wavelength is 270 nm.

[0062] SMX degradation rate (%) = (influent SMX concentration - effluent SMX concentration) / influent SMX concentration x 100%

[0063] 2. The influent in the reactor involved in the following examples and comparative examples is artificial synthetic wastewater: ammonia nitrogen concentration 100 mg / L to 500 mg / L, KH2PO4 64 mg / L, K2HPO4 64 mg / L, NaHCO3 4 g / L, trace element solution 2 mL / L, pH value 7.8 ± 0.2; wherein the composition of the trace element solution: ZnSO4·7H2O 0.55 g / L, MnCl2·4H2O 1.275 g / L, CoCl2 6H2O 0.4 g / L, CuSO4·5H2O 0.4 g / L, MgSO4·7H2O 44.4 g / L, FeCl3·6H2O 1.25 g / L, Na2MoO4·2H2O 0.05 g / L, CaCl2·2H2O 1.375 g / L, MgSO4·7H2O 44.4 g / L.

[0064] 3. R1 reactor refers to the ammonia-oxidizing sludge enrichment reactor operated under basic pH conditions in stage S1 and under acidic pH conditions in stages S2 to S4 in Example 1, and R2 reactor refers to the ammonia-oxidizing sludge enrichment reactor operated under basic pH conditions in stages S1 to S4 in Comparative Example 1.

[0065] Example 1: Enriched ammonia-oxidizing sludge co-metabolic degradation of sulfamethoxazole (SMX) under alkaline pH conditions in S1 stage and acidic pH conditions in S2-S4 stages

[0066] A method for enhancing the co-metabolic degradation of SMX by ammonia-oxidizing sludge, comprising the following steps:

[0067] (1) Start-up stage:

[0068] The method described in patent document CN115849574A was used to enrich ammonia-oxidizing sludge in the reactor, specifically:

[0069] 1) The inoculated sludge taken from the aeration tank of a sewage treatment plant was diluted with tap water and then introduced into the reactor, so that the initial mixed liquor suspended solids (MLSS) mass concentration in the reactor was 2000 mg / L;

[0070] 2) AAOB was enriched by gradually increasing the ammonia nitrogen concentration gradient of the influent:

[0071] Synthetic wastewater was introduced into the reactor at an influent rate of 16.67 mL / min and an effluent rate of 200 mL / min.

[0072] The reactor worked for 4 cycles per day, each cycle being 360 min, including 60 min of influent, 260 min of aeration (DO concentration was controlled at 0.5-1 mg / L using a rotor flowmeter), 30 min of sedimentation (simultaneous shutdown of influent, effluent, agitation, and aeration), 5 min of effluent, and 5 min of stagnation. The effluent ratio was 25%. The influent pH was adjusted to 7.8±0.2.

[0073] When the ammonia nitrogen concentration of the reactor effluent was less than 1 mg / L and stable operation lasted for 5 days, the ammonia nitrogen concentration of the synthetic wastewater was increased by 100 mg / L. When the ammonia nitrogen concentration of the reactor effluent was again less than 1 mg / L and stable operation lasted for 5 days, the ammonia nitrogen concentration of the synthetic wastewater was again increased by 100 mg / L each time, and this was repeated until the ammonia nitrogen concentration of the influent was gradually increased from 100 mg / L to 500 mg / L in 90 days. When the ammonia nitrogen concentration of the effluent was less than 1 mg / L, the operation was ended.

[0074] 3) After the end of the last working cycle, the microbial community in the sludge was detected. According to the microbial sequencing results, the AOB abundance accounted for 38.65% of the active sludge microorganisms, and AOB was successfully enriched;

[0075] The NH4HCO3 was additionally added to the influent of the SBR reactor as a nitrogen source (the concentration of the additional nitrogen source added to the influent was 2.8214 g / L), the KH2PO4 and K2HPO4 were additionally added as a phosphorus source (the concentration of the additional phosphorus source added to the influent was 0.064 g / L), 4 g / L of NaHCO3 was additionally added to control the pH to be 7.8±0.2, and the reaction was maintained for 70-80 days;

[0076] (2) Formal treatment:

[0077] The operation cycle of the SBR reactor was set to be 4 cycles per day, each cycle was 360 min, including influent for 60 min, aeration for 260 min, sedimentation for 30 min, drainage for 5 min and standing for 5 min; the drainage ratio was 25%;

[0078] The whole reaction in the SBR reactor was divided into 4 stages:

[0079] In the S1 stage, the ammonia nitrogen concentration in the influent was 400 mg / L, the alkaline condition (pH=7.8±0.2) was maintained, but no SMX was added, and the operation was maintained for 10-15 days;

[0080] In the S2 stage, the ammonia nitrogen concentration in the influent was adjusted to 500 mg / L, the acidic condition (pH=6.5±0.5) was adjusted by reducing the amount of NaHCO3 added, but no SMX was added, and the operation was maintained for 10-15 days;

[0081] In the S3 stage, on the basis of the acidic condition in the S2 stage, SMX was added to the influent of the reactor (the concentration of SMX in the influent was 1 mg / L), and the operation was maintained for 30-40 days;

[0082] In the S4 stage, on the basis of the acidic condition in the S2 stage, SMX was added to the influent of the reactor (the concentration of SMX in the influent was 5 mg / L), and the operation was maintained for 20-30 days.

[0083] The S1-S4 stages were totally operated for 95 days, and relevant indexes were determined every 2-4 days, multiple parallel samples were set for each sampling, and the average value of the test results of the multiple parallel samples was calculated as the treatment result.

[0084] The treatment effect of the ammonia-oxidizing sludge enrichment reactor under different SMX concentrations and acidic pH conditions in the S3 stage and the S4 stage:

[0085] The results are shown in Figure 1 、 Figure 3 、 Figure 4

[0086] (1) The degradation rate of SMX by the SBR reactor

[0087] ​S3 stage: When the SMX concentration in the influent was 1 mg / L, the SMX degradation rate in the R1 reactor was between 35.7 and 92.3% from the beginning of the S3 stage to the 38th day, with an average of 58.4%, and the fluctuation was large, but the overall degradation rate was good.

[0088] S4 stage: When the SMX concentration in the influent was increased to 5 mg / L, the SMX degradation rate in the R1 reactor decreased significantly at the beginning (from the beginning of the S3 stage to the 42nd day), and only 28.4% on the 42nd day, but the SMX degradation rate recovered to a high level with the extension of time, with an average of about 80%. After the SMX concentration in the influent was increased to 5 mg / L in the S4 stage, the NH3-N removal rate in the R1 reactor was impacted and maintained at about 85%.

[0089] (2) NH3-N removal rate of the SBR reactor

[0090] In the early stage of operation (from the beginning of the S1 stage to the 29th to 35th day), the NH3-N removal rate in the R1 reactor was impacted, with a minimum of only 82.7%;

[0091] In the middle stage of operation (from the beginning of the S1 stage to the 35th to 55th day), the AOB gradually adapted to the SMX impact, and the NH3-N removal rate gradually recovered and stabilized at about 88%;

[0092] And in the late stage of operation (from the beginning of the S1 stage to the 55th to 65th day), the performance of removing NH3-N improved significantly, and even on the 65th day, NH3-N could be completely removed.

[0093] (3) Ammonia oxidation rate (SAOR)

[0094] S3 stage:

[0095] When the SMX concentration in the influent was 1 mg / L, due to the impact of SMX, the SAOR in the R1 reactor decreased significantly from the beginning of the S1 stage to the 26th to 29th day, from 13.1 mg / (h·gMLVSS) to 7.6 mg / (h·gMLVSS), with a decrease of 42.0%. With the increase of operation time, the ammonia-oxidizing bacteria gradually adapted to the stress of SMX, and the SAOR slowly recovered, reaching 13.2 mg / (h·gMLVSS) on the 53rd day from the beginning of the S1 stage, and the NH3-N removal rate increased.

[0096] S4 stage:

[0097] After the concentration of SMX in the influent was increased to 5 mg / L, the SAOR in the R1 reactor decreased again, and was only 8.1 mg / (h.gMLVSS) on the 75th day of the S1 stage. After 10 days (the 85th day of the S1 stage), it increased again to 14.5 mg / (h.gMLVSS).

[0098] The average SAOR in the S3 and S4 stages after the addition of SMX was 10.6 mg / (h.gMLVSS).

[0099] Comparative Example 1: Co-metabolic degradation of sulfamethoxazole (SMX) by enriched ammonia-oxidizing sludge under alkaline pH conditions in the S1-S4 stages

[0100] The specific implementation is the same as in Example 1, except that the S2-S4 stages are under alkaline conditions (pH = 7.8 ± 0.2), and include the following steps:

[0101] (1) Start-up stage:

[0102] The ammonia-oxidizing sludge was enriched in the reactor using the method described in the patent document CN115849574A, and the specific implementation was the same as in Example 1;

[0103] NH4HCO3 was additionally added to the influent of the SBR reactor as a nitrogen source (the concentration of the additional nitrogen source in the influent was 2.8214 g / L), KH2PO4 and K2HPO4 were additionally added as a phosphorus source (the concentration of the additional phosphorus source in the influent was 0.064 g / L), and 4 g / L of NaHCO3 was additionally added to control the pH to 7.8 ± 0.2, and the process was maintained for 70-80 days;

[0104] (2) Formal treatment:

[0105] The operation cycle of the SBR reactor was set to 4 cycles per day, each cycle being 360 min, including 60 min of influent, 260 min of aeration, 30 min of sedimentation, 5 min of drainage, and 5 min of standing; the drainage ratio was 25%;

[0106] The entire reaction in the SBR reactor was divided into 4 stages:

[0107] The ammonia nitrogen concentrations in the influent in the S1 and S2 stages were 400 mg / L and 500 mg / L, respectively, and both were maintained under alkaline conditions (pH = 7.8 ± 0.2) without the addition of SMX, and the two stages were operated for 10-15 days each;

[0108] S3 stage: On the basis of the alkaline conditions in the S2 stage, SMX was added to the influent of the reactor (the concentration of SMX in the influent was 1 mg / L), and the process was operated for 30-40 days;

[0109] S4 stage: on the basis of the alkaline condition in S2 stage, SMX was added into the influent of the reactor (SMX concentration in the influent was 5 mg / L), and the reactor was operated for 20-30 days.

[0110] The total operation time of S1-S4 stages was 95 days. The related indexes were determined every 2-4 days, and multiple parallel samples were set for each sampling. The average value of the test results of the multiple parallel samples was calculated as the treatment result.

[0111] The treatment effect of the ammonia-oxidizing sludge enrichment reactor under different SMX concentrations and alkaline pH conditions in S3 and S4 stages:

[0112] The results are shown in Figures 2 to 4 .

[0113] (1) The degradation rate of SMX in the SBR reactor

[0114] In S3 stage, when the SMX concentration in the influent was 1 mg / L, the initial SMX degradation rate in R2 reactor could reach about 50% in the first 1-2 days, but the degradation rate decreased with the prolongation of the operation time and maintained at a low level of fluctuation, only about 7.4%.

[0115] In S4 stage, when the SMX concentration in the influent was increased to 5 mg / L, the average degradation rate in R2 reactor remained at a low level of fluctuation, only 13%, in the 43rd-60th day from the beginning of S3 stage. The NH3-N removal rate in this stage was not significantly affected.

[0116] (2) The NH3-N removal rate in the SBR reactor

[0117] In the early stage of operation (29th-35th day from the beginning of S1 stage), the NH3-N removal rate in R2 reactor was impacted, lower than 90%;

[0118] In the middle stage of operation (35th-55th day from the beginning of S1 stage), the ammonia-oxidizing bacteria gradually adapted to the SMX impact, and the NH3-N removal rate gradually recovered and could always be maintained above 90%;

[0119] In the late stage of operation (55th-65th day from the beginning of S1 stage), the NH3-N removal rate in R2 reactor decreased to below 90%.

[0120] (3) Ammonia oxidation rate (SAOR)

[0121] The SAOR in the R2 reactor only decreased obviously at the beginning of the S3 stage (from the 26th to 29th day) and at the beginning of the S4 stage (from the 53rd to 68th day) after the SMX was added, and then slowly increased. The average value of the two stages was 12.1 mg / (h.gMLVSS), which was the same as the R1 reactor in Example 1.

[0122] Comparative Example 2: Co-metabolic degradation of sulfamethoxazole (SMX) by ammonia-oxidizing sludge enrichment under acidic pH conditions in S1-S4 stages

[0123] The specific implementation is the same as that in Example 1, except that the S1-S4 stages are all adjusted to acidic conditions (pH = 6.5 ± 0.5), and other conditions remain unchanged, for degrading sulfamethoxazole (SMX).

[0124] Since ammonia-oxidizing bacteria are more suitable for domestication and adaptation under alkaline conditions (pH = 7.8 ± 0.2), otherwise it is not conducive to the enrichment, therefore, adjusting the S1-S4 stages to acidic pH conditions is not conducive to the subsequent degradation of sulfamethoxazole.

[0125] Comparative Example 3: Co-metabolic degradation of sulfamethoxazole (SMX) by ammonia-oxidizing sludge enrichment under acidic pH conditions in S1 stage and alkaline pH conditions in S2-S4 stages

[0126] The specific implementation is the same as that in Example 1, except that the S1 stage is adjusted to acidic conditions (pH = 6.5 ± 0.5), and the S2-S4 stages are adjusted to alkaline conditions (pH = 7.8 ± 0.2), and other conditions remain unchanged, for degrading sulfamethoxazole (SMX).

[0127] Since ammonia-oxidizing bacteria are more suitable for domestication and adaptation under alkaline conditions (pH = 7.8 ± 0.2), otherwise it is not conducive to the enrichment, therefore, adjusting the S1 stage to acidic pH conditions is not conducive to the degradation of sulfamethoxazole, and the alkaline pH conditions in the S2 stage cannot achieve the subsequent degradation of sulfamethoxazole (SMX).

[0128] Although the present application has been disclosed with reference to the preferred embodiments above, it is not intended to limit the present application, and anyone skilled in the art can make various modifications and modifications without departing from the spirit and scope of the present application, therefore, the protection scope of the present application should be defined by the claims.

Claims

1. A method for degrading sulfonamide antibiotics in sewage, characterized by, The method comprises the following steps: (1) starting stage: Enriching ammonia-oxidizing sludge in a reactor; Adding nitrogen source and phosphorus source to influent of the reactor, controlling pH to be 7.5-8, and maintaining for 70-80 days; (2) formal treatment: Setting operation cycle of the reactor and dividing the whole reaction into four stages: S1 stage: influent is sewage, maintaining alkaline condition for 10-15 days; S2 stage: influent is sewage, adjusting to acidic condition for 10-15 days; S3 stage: influent is sewage containing antibiotics, and maintaining for 30-40 days; S4 stage: influent is sewage containing antibiotics, and maintaining for 20-30 days; In S2-S4 stages, pH is acidic condition, and pH is 6-7; In S3 stage, the concentration of antibiotics in influent is 0.5-1.5 mg / L; In S4 stage, the concentration of antibiotics in influent is 4-6 mg / L.

2. The method of claim 1, wherein, In step (1), the nitrogen source is NH4HCO3, and the concentration of the additional nitrogen source in influent is 2.5-2.85 g / L; the phosphorus source is one or more of K2HPO4 and KH2PO4, and the concentration of the additional phosphorus source in influent is 0.06-0.07 g / L.

3. The method of claim 1, wherein, In step (2), the alkaline condition in S1 stage is pH=7.5-8.

4. The method of claim 1, wherein, In step (2), the reactor is SBR reactor, and the operation cycle of the SBR reactor is 4 cycles per day, each cycle is 360 min, including 60 min of influent, 260 min of aeration, 30 min of sedimentation, 5 min of drainage and 5 min of standing; the drainage ratio is 25%.

5. The method of claim 1, wherein, In step (2), the influent in S3 and S4 stages is sewage containing antibiotics, and the antibiotics is sulfamethoxazole.

6. The use of the method according to any one of claims 1-5 in enhancing degradation of sewage containing antibiotics.

7. The use of the method according to any one of claims 1-5 in enhancing degradation of sewage containing ammonia nitrogen.

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