Method for enhancing co-metabolism degradation of antibiotics in ammoxidation sludge

Abstract

The invention discloses a method for enhancing co-metabolism degradation of antibiotics in ammoxidation sludge, and belongs to the technical field of sewage treatment. According to the method, ammonia oxidation sludge is enriched firstly, artificially synthesized sewage is used as inlet water of an ammonia oxidation sludge enrichment reactor, the reactor is operated by adjusting the pH value to be acidic, sulfamethoxazole with different concentrations in the inlet water is treated in stages, co-metabolism of the ammonia oxidation sludge is enhanced, and sulfamethoxazole degradation is enhanced under the long-term operation condition; the ammonia nitrogen removal rate is not obviously inhibited. The method provided by the invention not only can remove ammonia nitrogen in sewage, but also can efficiently and stably degrade antibiotics, and can reduce propagation and invasion of pathogens in nature, thereby protecting biodiversity and stability of an ecological system.

Description

Technical Field

[0001] The invention relates to a method for strengthening the cometabolism degradation of antibiotics by ammonia oxidation sludge, and belongs to the technical field of sewage treatment. Background Art

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

[0003] Antibiotics are very harmful to the human body, including interfering with intestinal microorganisms, affecting the immune system and causing a variety of adverse reactions. The abuse of antibiotics in animal husbandry will endanger the health of animals, reduce their immunity and disease resistance, and remain in meat, milk, eggs and other products, threatening human food safety and health. In addition, antibiotics, as antibacterial drugs, have certain biological toxicity. The residual antibiotics in the environment will kill non-resistant microorganisms and screen out resistant bacteria, thereby changing the local microbial community and affecting higher organisms through the food chain, destroying the local ecological balance. Among them, sulfonamide antibiotics, such as sulfadimethoxine, sulfadiazine, sulfamethoxazole, etc., are widely used in the treatment of human and animal diseases. They are particularly widely used in animal husbandry, and even lead to the rampant spread of sulfonamide antibiotics in the human living environment. Existing literature shows that the content of sulfonamide antibiotics in sewage treatment plants ranks among the top three. Sewage treatment plants have become one of the main gathering places for antibiotics, and due to the increasing use of antibiotics, their concentrations in the influent and effluent of sewage treatment plants have also shown a gradual increasing trend.

[0004] Existing antibiotic degradation technologies mainly include adsorption, advanced oxidation, membrane separation, artificial wetland and biological methods. Biological method is one of the most commonly used technologies, with low operating costs and 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, greatly affected by external environmental conditions, and unable to inhibit the spread of drug-resistant bacteria.

[0005] In recent years, more and more studies have shown that the cometabolism of ammonia oxidizing bacteria (AOB) is one of the effective ways to enhance the degradation of new pollutants such as antibiotics. Cometabolism is the induction of microorganisms to produce non-specific enzymes to decompose and transform non-growth substrates such as antibiotics in the presence of microbial growth substrates and the ability to provide sufficient carbon source or energy. This is due to the presence of a non-specific functional enzyme in AOB, ammonia monooxygenase (AMO). AMO has a wide range of substrates and can cometabolize and degrade new pollutants such as antibiotics while oxidizing ammonia. In previous studies, the main research directions were the relationship between the degradation rate of antibiotics and the rate of ammonia oxidation, the identification of degradation products, etc., which are conducive to further understanding the degradation path of antibiotics. However, the above studies are limited to laboratory conditions and do not take into account the suitable conditions of actual sewage treatment plants. In actual sewage 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 cometabolism degradation of AOB to achieve the purpose of efficient and stable degradation of antibiotics.

[0006] In addition, the biocidal / inhibitory effects of free nitrite (FNA) can be applied to multiple units of urban sewage systems to improve the comprehensive management of sewage systems. However, in order to produce the required concentration of FNA, nitrite and acid must be added at the same time, which further increases chemical costs. The ammonia oxidation process, as the rate-limiting step of nitrification, involves microorganisms oxidizing ammonia (NH3) to nitrite (NO2 - ), and the ammonia oxidation process is mainly driven by AOB, ammonia oxidizing archaea (AOA) and comammox, and FNA will have a certain inhibitory effect on nitrite oxidizing bacteria (NOB).

[0007] In summary, how to effectively utilize the cometabolic degradation of AOB and the abiotic degradation of FNA to efficiently and stably degrade antibiotics in wastewater is crucial for the treatment of antibiotic-containing wastewater. Summary of the invention

[0008] In order to solve one or more of the above problems, the present invention enriches ammonia oxidation sludge, uses artificial synthetic sewage as the influent of the ammonia oxidation sludge reactor to conduct experiments, adjusts the pH of the reaction S2 to S4 stages to acidic conditions, operates the reactor (R1), and adds sulfamethoxazole (SMX) with a final concentration of 1 mg / L and 5 mg / L to the influent in the reaction S3 and S4 stages, respectively, making full use of the non-biological degradation of FNA and the co-metabolism degradation of AOB, and efficiently and stably degrading antibiotics in sewage. In addition, the present invention can also effectively remove ammonia nitrogen in sewage, greatly improving the sewage treatment efficiency.

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

[0010] (1) Start-up phase:

[0011] enriching ammonia-oxidized sludge in a reactor;

[0012] Additional nitrogen and phosphorus sources were added to the influent of the reactor to control the pH to be maintained at 7.5-8 for 70-80 days;

[0013] (2) Formal processing:

[0014] Set the reactor's operating cycle and divide the entire reaction into 4 stages:

[0015] In the S1 stage, the influent is sewage, and the alkaline conditions are maintained for 10 to 15 days;

[0016] In the S2 stage, the influent is sewage, and the acidic conditions are adjusted to operate for 10 to 15 days;

[0017] The influent of the S3 stage is sewage containing antibiotics, which runs for 30 to 40 days;

[0018] The influent in the S4 stage is sewage containing antibiotics, which runs for 20 to 30 days.

[0019] In one 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 one 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 one embodiment, in step (1), the pH is controlled to be 7.5-8 by adding NaHCO3.

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

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

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

[0025] In one embodiment, in step (2), the influent water in stages S3 and S4 is sewage containing antibiotics, and the antibiotics are one or more of sulfonamide antibiotics, macrolide antibiotics, tetracycline antibiotics, and polyamine antibiotics, preferably sulfonamide antibiotics, and more preferably sulfamethoxazole.

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

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

[0028] In one embodiment, in step (2), the alkaline conditions (pH=7.5-8) described in stage S1 are the most suitable conditions for the growth of AOB.

[0029] In one embodiment, there are 4 stages in step (2):

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

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

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

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

[0034] In one embodiment, in step (1), the enriched ammonia oxidation sludge comprises the following steps:

[0035] (1) diluting the inoculated sludge with tap water and then connecting it to the reactor;

[0036] (2) artificial synthetic sewage is introduced into the reactor, and the reactor is operated in a working cycle in the manner of water inlet, aeration, sedimentation, drainage, and stagnation; during the aeration process, the DO concentration is controlled at 0.5-1 mg / L using a rotor flowmeter;

[0037] When the ammonia nitrogen concentration of the reactor effluent is lower than 1 mg / L and has been running stably 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 lower than 1 mg / L again and has been running stably for 5 days, the ammonia nitrogen concentration of the artificial synthetic sewage is increased again by 100 mg / L each time, and this 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) After 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 disk.

[0040] In one embodiment, the sewage is artificial synthetic sewage, and the formula of the artificial synthetic sewage is: ammonia nitrogen concentration 100mg / L~500mg / L, KH2PO4 64mg / L, K2HPO4 64mg / L, NaHCO3 4g / L, trace element solution 2mL / L, pH value 7.8±0.2; wherein the trace element solution components: ZnSO4·7H2O 0.55g / L, MnCl2·4H2O 1.275g / L, CoCl26H2O 0.4g / L, CuSO4·5H2O 0.4g / L, MgSO4·7H2O 44.4g / L, FeCl3·6H2O 1.25g / L, Na2MoO4·2H2O 0.05g / L, CaCl2·2H2O 1.375g / L, MgSO4·7H2O 44.4g / L.

[0041] In one embodiment, the method is achieved by adjusting the pH condition of the S2 stage to an acidic condition to enhance the cometabolism of the ammonia oxidation sludge.

[0042] The second object of the present invention is to provide an application of the above method in enhancing the degradation of sewage containing antibiotics.

[0043] The third object of the present invention is to provide an application of the above method in enhancing the degradation of wastewater containing ammonia nitrogen.

[0044] Beneficial Effects

[0045] (1) The present invention adjusts the pH of the S2-S4 stage to an acidic condition and operates the reactor, which is denoted as R1. At the same time, the reactor R2 operated at an alkaline pH of the S1-S4 stage is compared. SMX is added to the influent of the S3 and S4 stages in stages to a concentration of 1 mg / L and 5 mg / L. It is found that the acidic pH condition can enhance the co-metabolic degradation of SMX by ammonia oxidation sludge. At the same time, under long-term operation conditions, the NH3-N removal rate is not significantly inhibited;

[0046] (2) The present invention makes full use of the property of ammonia oxidizing bacteria that can cometabolize and biodegrade antibiotics, adjusts the pH of the S2-S4 stage to be acidic, and generates nitrite during the ammonia oxidation process. Free nitrous acid (FNA) can chemically degrade antibiotics. The present invention has both cometabolism and chemical degradation of FNA, and the two synergistically enhance the degradation of antibiotics.

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

[0048] Figure 1 This is a graph showing the degradation rate of sulfamethoxazole in the enriched ammonia oxidation sludge reactor operated under alkaline pH conditions in the S1 stage and acidic pH conditions in the S2 to S4 stages in Example 1;

[0049] Figure 2 It is a graph showing the degradation rate of sulfamethoxazole in the enriched ammonia oxidation sludge reactor operated under alkaline pH conditions in stages S1 to S4 in Comparative Example 1;

[0050] Figure 3 It is a graph showing the removal rate of ammonia nitrogen by the enriched ammonia oxidation sludge reactor in Example 1 and Comparative Example 1;

[0051] Figure 4 Graph showing the specific ammonia oxidation rate of the enriched ammonia oxidation sludge reactor in Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0052] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0053] First, the relevant detection methods / calculation formulas, water inflow conditions and technical terms involved in the present invention are introduced as follows:

[0054] 1. Test methods / calculation formulas involved in the following examples and comparative examples:

[0055] (1) Ammonia nitrogen concentration

[0056] The content was determined by spectrophotometry using Nessler's reagent.

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

[0058] (2) Specific ammonia oxidation rate (SAOR)

[0059] The AOR is obtained by calculating the ratio of the ammonia oxidation rate AOR to the volatile suspended solids concentration MLVSS of the mixed liquor. Water samples are taken from the reactor every 10 minutes within 1 hour and the ammonia nitrogen concentration at each time period is measured. The slope of the straight line obtained by linear fitting is the AOR. MLVSS is determined by the weight method.

[0060] (3) Sulfamethoxazole (SMX) concentration

[0061] High-performance liquid chromatography (HPLC) was used for determination. The HPLC column was a C18 column (250×4.6 mm, 5 μm; Agilent Technologies, Germany), the mobile phase A was acetonitrile, the mobile phase B was 0.1% formic acid solution, the liquid flow rate was 1 mL / min, the column temperature was 30°C, the injection volume was 10 μL, and the detection wavelength was 270 nm.

[0062] Degradation rate of SMX (%) = (influent SMX concentration - effluent SMX concentration) / influent SMX concentration × 100%

[0063] 2. The influent in the reactor involved in the following embodiments and comparative examples is artificial synthetic sewage: ammonia nitrogen concentration 100mg / L-500mg / L, KH2PO4 64mg / L, K2HPO4 64mg / L, NaHCO3 4g / L, trace element solution 2mL / L, pH value 7.8±0.2; wherein the trace element solution components: ZnSO4·7H2O 0.55g / L, MnCl2·4H2O 1.275g / L, CoCl26H2O0.4g / L, CuSO4·5H2O 0.4g / L, MgSO4·7H2O 44.4g / L, FeCl3·6H2O 1.25g / L, Na2MoO4·2H2O0.05g / L, CaCl2·2H2O 1.375g / L, MgSO4·7H2O 44.4g / L.

[0064] 3. The R1 reactor refers to the enriched ammonia oxidation sludge reactor in Example 1 which operates under alkaline pH conditions in the S1 stage and acidic pH conditions in the S2 to S4 stages, and the R2 reactor refers to the enriched ammonia oxidation sludge reactor in Comparative Example 1 which operates under alkaline pH conditions in the S1 to S4 stages.

[0065] Example 1: Cometabolic degradation of sulfamethoxazole (SMX) by enriched ammonia oxidation sludge under alkaline pH conditions in stage S1 and acidic pH conditions in stages S2 to S4

[0066] A method for enhancing the cometabolic degradation of SMX by ammonia oxidation sludge comprises the following steps:

[0067] (1) Start-up phase:

[0068] The method described in patent document CN115849574A is used to enrich ammonia oxidation sludge in a reactor, specifically:

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

[0070] 2) Enrichment and cultivation of AOB by gradually increasing the ammonia nitrogen concentration gradient of the influent:

[0071] Artificial synthetic sewage was introduced into the reactor, with an inlet rate of 16.67 mL / min and an outlet rate of 200 mL / min.

[0072] The reactor works 4 cycles per day, each cycle is 360 minutes, including 60 minutes of water inlet, 260 minutes of aeration (using a rotor flowmeter to control the DO concentration to 0.5-1 mg / L), 30 minutes of sedimentation (meaning that the water inlet, water outlet, stirring and aeration are closed at the same time), 5 minutes of drainage and 5 minutes of stagnation. The drainage ratio is 25%. The pH value of the inlet water is adjusted to 7.8±0.2.

[0073] When the ammonia nitrogen concentration of the reactor effluent is lower than 1 mg / L and has been running stably 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 lower than 1 mg / L again and has been running stably for 5 days, the ammonia nitrogen concentration of the artificial simulated wastewater is increased again, by 100 mg / L each time. This process is repeated, and the ammonia nitrogen concentration of the influent is gradually increased from 100 mg / L to 500 mg / L within 90 days. When the ammonia nitrogen concentration of the effluent is lower than 1 mg / L, the operation is terminated.

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

[0075] 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), KH2PO4 and K2HPO4 were additionally added as phosphorus sources (the concentration of the additional phosphorus source added to 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 for 70 to 80 days;

[0076] (2) Formal processing:

[0077] The operation cycle of the SBR reactor is set to 4 cycles per day, each cycle is 360 minutes, including 60 minutes of water inlet, 260 minutes of aeration, 30 minutes of sedimentation, 5 minutes of drainage and 5 minutes of standing; the drainage ratio is 25%;

[0078] The entire reaction in the SBR reactor is divided into 4 stages:

[0079] S1 stage: The ammonia nitrogen concentration in the influent was 400 mg / L, and the system was operated under alkaline conditions (pH = 7.8 ± 0.2), but SMX was not added, and the system was operated for 10 to 15 days;

[0080] S2 stage: The ammonia nitrogen concentration in the influent was adjusted to 500 mg / L, and the operation was adjusted to acidic conditions (pH = 6.5 ± 0.5) by reducing the dosage of NaHCO3, but without adding SMX, and operated for 10 to 15 days;

[0081] S3 stage: Based on the acidic conditions of S2 stage, SMX is added to the influent of the reactor (the concentration of SMX in the influent is 1 mg / L) and the reactor is operated for 30 to 40 days;

[0082] S4 stage: Based on the acidic conditions of S2 stage, SMX is added to the influent of the reactor (the concentration of SMX in the influent is 5 mg / L) and operated for 20 to 30 days.

[0083] The S1 to S4 stages were run for a total of 95 days. Samples were taken every 2 to 4 days to measure relevant indicators. Multiple parallel samples were set each time, and the average value of the test results of multiple parallel samples was calculated as the processing result.

[0084] Treatment effects of the enriched ammonia oxidation sludge reactor under different SMX concentrations and acidic pH conditions in the S3 and S4 stages:

[0085] The results are as follows Figure 1 , Figure 3 , Figure 4 As shown:

[0086] (1) Degradation rate of SMX in SBR reactor

[0087] S3 stage: When the SMX concentration in the influent is 1 mg / L, the S3 stage begins. From the 1st to the 38th day, the degradation rate of SMX in the R1 reactor is between 35.7% and 92.3%, with an average value of 58.4%. There is a large fluctuation, but the overall degradation rate is good.

[0088] S4 stage: After the SMX concentration in the influent was increased to 5 mg / L, the degradation rate of SMX in the R1 reactor dropped significantly in the early stage (starting from the S3 stage, 38-42 days), and was only 28.4% on the 42nd day. However, as time went on, the SMX degradation rate recovered to a higher level, averaging 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) Removal rate of ammonia nitrogen by SBR reactor

[0090] At the beginning of operation (starting from S1 stage, 29-35 days), the NH3-N removal rate in the R1 reactor was impacted, with the lowest being only 82.7%;

[0091] In the middle of operation (starting from S1 stage, 35-55 days), AOB gradually adapted to SMX shock, and the NH3-N removal rate gradually recovered and stabilized at about 88%.

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

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

[0094] S3 stage:

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

[0096] S4 stage:

[0097] After increasing the SMX concentration in the influent to 5 mg / L, the SAOR in the R1 reactor dropped significantly again from the 53rd to the 75th day starting from the S1 stage. From the beginning of the S1 stage, it was only 8.1 mg / (h·gMLVSS) on the 75th day. Ten days later (from the beginning of the S1 stage, the 85th day), it rose again to 14.5 mg / (h·gMLVSS).

[0098] After the addition of SMX, the average SAOR in the two stages S3 and S4 was 10.6 mg / (h·gMLVSS).

[0099] Comparative Example 1: Cometabolic degradation of sulfamethoxazole (SMX) by enriched ammonia oxidation sludge operated under alkaline pH conditions in stages S1 to S4

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

[0101] (1) Start-up phase:

[0102] The method described in patent document CN115849574A is used to enrich ammonia oxidation sludge in the reactor, which is 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 added to the influent was 2.8214 g / L), KH2PO4 and K2HPO4 were additionally added as phosphorus sources (the concentration of the additional phosphorus source added to 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 for 70 to 80 days;

[0104] (2) Formal processing:

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

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

[0107] The ammonia nitrogen concentration in the influent of the S1 stage and the S2 stage was 400 mg / L and 500 mg / L, respectively. Both stages were operated under alkaline conditions (pH = 7.8 ± 0.2), but no SMX was added. The two stages were operated for 10 to 15 days respectively.

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

[0109] S4 stage: Based on the alkaline conditions of the S2 stage, SMX is added to the influent of the reactor (the concentration of SMX in the influent is 5 mg / L) and operated for 20 to 30 days.

[0110] The S1 to S4 stages were run for a total of 95 days. Samples were taken every 2 to 4 days to measure relevant indicators. Multiple parallel samples were set each time, and the average value of the test results of multiple parallel samples was calculated as the processing result.

[0111] Treatment effects of the enriched ammonia oxidation sludge reactor under different SMX concentrations and alkaline pH conditions in the S3 and S4 stages:

[0112] The results are as follows Figures 2 to 4 As shown:

[0113] (1) Degradation rate of SMX in SBR reactor

[0114] S3 stage: When the SMX concentration in the influent is 1 mg / L, the S3 stage begins. On the 1st to 2nd day, the initial SMX degradation rate in the R2 reactor can reach about 50%, but as the operating time increases, the degradation rate decreases and remains at a low level of fluctuation, only about 7.4%.

[0115] S4 stage: After the SMX concentration in the influent increased to 5 mg / L, the S3 stage began. From the 43rd to the 60th day, the R2 reactor still maintained a low level of fluctuation, with an average degradation rate of only 13%. The NH3-N removal rate was not significantly affected during this stage.

[0116] (2) Removal rate of ammonia nitrogen by SBR reactor

[0117] At the beginning of operation (starting from S1 stage, 29-35 days), the NH3-N removal rate in the R2 reactor was impacted and was lower than 90%;

[0118] In the middle of operation (starting from S1 stage, 35-55 days), ammonia oxidizing bacteria gradually adapt to SMX shock, and the NH3-N removal rate gradually recovers and can be kept above 90% all the time.

[0119] At the end of the operation (starting from the S1 stage, 55-65 days), the NH3-N removal rate in the R2 reactor dropped below 90%.

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

[0121] The SAOR in the R2 reactor decreased significantly only when SMX was added at the beginning of the S3 stage (the 26th to 29th day from the beginning of the S1 stage) and the beginning of the S4 stage (the 53rd to 68th day from the beginning of the S1 stage), and then slowly recovered. Similar to the R1 reactor in Example 1, the average value in the two stages was 12.1 mg / (h·gMLVSS).

[0122] Comparative Example 2: Cometabolic degradation of sulfamethoxazole (SMX) by enriched ammonia oxidation sludge operated under acidic pH conditions in stages S1 to S4

[0123] The specific implementation method is the same as Example 1, except that the conditions in stages S1 to S4 are all adjusted to acidic conditions (pH=6.5±0.5), and other conditions remain unchanged, and are used to degrade 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 their enrichment, adjusting the S1 to S4 stages to acidic pH conditions is not conducive to the subsequent degradation of sulfamethoxazole.

[0125] Comparative Example 3: Co-metabolism of SMX by enriched ammonia oxidation sludge under acidic pH conditions in S1 and alkaline pH conditions in S2-S4

[0126] The specific implementation method is the same as Example 1, except that the S1 stage is adjusted to an acidic condition (pH=6.5±0.5), and the S2-S4 stages are adjusted to an alkaline condition (pH=7.8±0.2), and other conditions remain unchanged for the degradation of 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 their enrichment. Therefore, on the basis that the S1 stage is adjusted to acidic pH conditions, which is not conducive to the degradation of sulfamethoxazole, the alkaline pH conditions in the S2 stage cannot effectively achieve the subsequent degradation of sulfamethoxazole (SMX).

[0128] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. A method for degrading antibiotics in sewage, characterized in that: The steps include: (1) Start-up phase: enriching ammonia-oxidized sludge in a reactor; Additional nitrogen and phosphorus sources were added to the influent of the reactor to control the pH to be maintained at 7.5-8 for 70-80 days; (2) Formal processing: Set the reactor's operating cycle and divide the entire reaction into 4 stages: In the S1 stage, the influent is sewage, and the alkaline conditions are maintained for 10 to 15 days; In the S2 stage, the influent is sewage, and the acidic conditions are adjusted to operate for 10 to 15 days; The influent of the S3 stage is sewage containing antibiotics, which runs for 30 to 40 days; The influent in the S4 stage is sewage containing antibiotics, which runs for 20 to 30 days.

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

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

4. The method according to claim 1, characterized in that In step (2), the acidic condition in stage S2 is pH=6-7.

5. The method according to claim 1, characterized in that: In step (2), the reactor is an SBR reactor, and the operation cycle of the SBR reactor is 4 cycles per day, each cycle is 360 minutes, including 60 minutes of water intake, 260 minutes of aeration, 30 minutes of sedimentation, 5 minutes of drainage and 5 minutes of standing; the drainage ratio is 25%.

6. The method according to claim 1, characterized in that In step (2), the influent in stages S3 and S4 is sewage containing antibiotics, wherein the antibiotics are one or more of sulfonamide antibiotics, macrolide antibiotics, tetracycline antibiotics, and polyamine antibiotics, preferably sulfonamide antibiotics, and more preferably sulfamethoxazole.

7. The method according to claim 6, characterized in that In step (2), the influent of stage S3 is sewage containing antibiotics, and the concentration of antibiotics in the influent is 0.5-1.5 mg / L.

8. The method according to claim 6, characterized in that In step (2), the influent of stage S4 is sewage containing antibiotics, and the concentration of antibiotics in the influent is 4-6 mg / L.

9. Use of the method according to any one of claims 1 to 8 in enhancing the degradation of sewage containing antibiotics.

10. Use of the method according to any one of claims 1 to 8 in enhancing the degradation of wastewater containing ammonia nitrogen.

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