Antibiotic wastewater coupling treatment method and system

Abstract

The invention discloses an antibiotic wastewater coupling treatment method and system and belongs to the technical field of water treatment. The method comprises the following steps: antibiotic wastewater containing persulfate is injected into a fixed bed reactor, a persulfate oxidation reaction is carried out, the fixed bed reactor is filled with a composite catalyst and an inert filler, and the composite catalyst is a biomass charcoal in-situ growth cobalt-molybdenum bimetallic composite material; the wastewater subjected to the oxidation reaction in the fixed bed reactor is mixed with a nutrient source required by biological metabolism, the mixture is injected into a sequencing batch bioreactor for an aerobic biological reaction, and the sequencing batch bioreactor is filled with a composite biological system formed by kaolin and activated sludge. According to the method, the mineralization degree can be greatly improved, damage to microorganisms caused by ion precipitation in the catalyst can be avoided, the pH value does not need to be independently adjusted, the problem of iron mud treatment does not exist, and long-term stable operation can be achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water treatment, in particular to a method and system for advanced treatment of antibiotic wastewater by coupling of persulfate oxidation and biological treatment. BACKGROUND

[0002] With the extensive use of antibiotics in the fields of pharmaceutical, medical and aquaculture, a large amount of antibiotic-containing wastewater is discharged into the environment. Such wastewater is complex in composition, high in concentration, refractory and highly toxic, mainly including antibiotic raw drugs, metabolites and organic solvent residues, which not only inhibit the microbial activity in conventional biological treatment systems, but also promote the generation and spread of antibiotic resistance genes, causing significant ecological risks and potential public health hazards. Therefore, efficient and harmless treatment of antibiotic wastewater has become an important scientific and engineering problem in current environmental governance. Current methods for treating antibiotic wastewater mainly include physical method, advanced oxidation method and biological method.

[0003] The physical method separates antibiotics through physical processes such as adsorption or membrane filtration, relying on π-π interaction, hydrophobic interaction and hydrogen bond interaction for interception. This method is simple to operate, but is limited by adsorption saturation and material regeneration, and more importantly, due to long-term adsorption, the antibiotics in the desorption liquid after cleaning of the adsorption material will be concentrated, forming a high-concentration concentrated liquid, so the physical method is only limited to pollution transfer rather than pollution treatment.

[0004] The biological method uses microorganisms to metabolize and decompose pollutants as nutrients and energy substances, achieving degradation or mineralization of pollutants. Typical biological treatment processes include activated sludge method, membrane bioreactor and biological filter. Biological method is the most commonly used treatment technology in wastewater treatment process due to its large water treatment capacity, complete removal effect, low investment and operation cost, etc. However, when treating antibiotic wastewater, biological treatment process needs to withstand the pressure of antibiotics on microorganisms, and the process has poor running stability, low antibiotic removal efficiency, and requires a long hydraulic retention time and sludge age to achieve antibiotic removal. Moreover, the continuous stress of long-term antibiotics in the influent will increase the absolute abundance of antibiotic resistance genes in sludge and effluent, leading to secondary pollution.

[0005] The advanced oxidation method realizes the oxidative decomposition of organic matter by generating active oxygen species with strong oxidizing ability, so that large molecular refractory organic matter is oxidized into small molecular substances with low or no toxicity. Existing technologies include ozone oxidation method, Fenton method, electrochemical oxidation method and persulfate oxidation method. Among them, the persulfate oxidation method has higher safety and operational convenience than the traditional Fenton method. However, the advanced oxidation process is high in cost and difficult to completely remove pollutants.

[0006] Therefore, the traditional processes have certain limitations in treating antibiotic wastewater, and currently, coupling different processes has been studied, and the existing literature mostly adopts "Fenton-biological" coupling, however, the method sets up a Fenton reaction before biological treatment, needs to adjust the pH of the influent to be acidic, and also will face the problem of difficult disposal of iron sludge. SUMMARY

[0007] (I) Invention purposes The purpose of the present application is to provide an antibiotic wastewater coupling treatment method and system, by first using biomass charcoal in-situ growth cobalt-molybdenum double-metal composite material as a catalyst, so that the persulfate oxidant can decompose the rigid condensed ring structure of antibiotics (such as ciprofloxacin, CIP) into low-toxicity small molecules, realizing effective degradation of CIP, and then through the composite biological system formed by kaolin and activated sludge, continuing the aerobic biological reaction on the effluent of the oxidation stage, which can not only improve the mineralization degree, but also avoid the damage to microorganisms caused by the precipitation of ions in the catalyst, and the method does not need to adjust the pH value separately, and there is no problem of iron sludge treatment, and can be operated stably for a long time.

[0008] (II) Technical solutions To solve the above problems, the first aspect of the present application provides an antibiotic wastewater coupling treatment method, comprising the following steps: Step 1: injecting antibiotic wastewater containing persulfate into a fixed bed reactor to carry out persulfate oxidation reaction, wherein the fixed bed reactor is filled with a composite catalyst and an inert filler, and the composite catalyst is a biomass charcoal in-situ growth cobalt-molybdenum double-metal composite material; Step 2: mixing the wastewater after the oxidation reaction in the fixed bed reactor with a nutrient source required for biological metabolism, and then injecting it into a sequencing batch reactor (SBR) to carry out aerobic biological reaction, wherein the SBR is filled with a composite biological system formed by kaolin and activated sludge.

[0009] Specifically, the antibiotic wastewater according to the present application refers to industrial discharge wastewater containing antibiotics and / or domestic discharge sewage containing antibiotics. The inert filler refers to a fixed bed reactor commonly used filler such as quartz sand and polyurethane sponge, and the composite catalyst and the inert filler are stirred and mixed and then filled in the fixed bed reactor. The fixed bed reactor is preferably made of organic glass and is a cylindrical reactor with an inner diameter of 1-2 cm and a length of 10-20 cm. The nutrient source required for biological metabolism refers to a mixture that can provide necessary carbon source, nitrogen source and other nutrients for microbial metabolism in aerobic biological reaction.

[0010] Specifically, the antibiotic concentration in the antibiotic wastewater is 5-40 mg / L, and the antibiotic can be selected from at least one of CIP, sulfamethoxazole, and terramycin, preferably CIP.

[0011] Specifically, the specific conditions of the sulfate oxidation reaction in step 1 include: The dosage concentration of persulfate in the antibiotic wastewater containing persulfate is 0.15-0.9 mM in terms of hydrogen peroxymonosulfate; The mass ratio of the composite catalyst to the inert filler is 1:2-5; The hydraulic retention time is 18-30 min; The reaction is carried out at room temperature without special adjustment of pH.

[0012] When the PMS oxidation reaction is carried out under this condition, the dosage concentration of persulfate is <1 mM, which can not only ensure that the concentration of antibiotics in the effluent is <0.1 mg / L, but also avoid the damage of residual oxidant to microorganisms in the aerobic biological reaction, so that the mineralization degree of more than 68% can still be achieved in the continuous operation of the aerobic biological reaction stage for 14 days.

[0013] Preferably, the concentration of antibiotics in the wastewater after the oxidation reaction by the fixed bed reactor is <0.1 mg / L.

[0014] The mixing of the wastewater after the oxidation reaction by the fixed bed reactor with the nutrient source required for biological metabolism in step 2 specifically includes: after mixing, the chemical oxygen demand is 200-300 mg / L, and the ammonia nitrogen is 50-100 mg / L.

[0015] In a specific embodiment, the nutrient source required for biological metabolism includes a nutrient salt and a mineral water solution, the nutrient salt is directly added to the wastewater after the oxidation reaction by the fixed bed reactor, and after addition, the nutrient components in the wastewater after the oxidation reaction by the fixed bed reactor include: CH3COONa 320 mg / L, NH4Cl 267 mg / L, KH2PO3 13 mg / L, MgSO4·7H2O 60 mg / L, CaCl2·2H2O 14 mg / L, and NaHCO3 1.0 g / L. 1 mL of mineral water solution is added per liter of wastewater after the oxidation reaction by the fixed bed reactor. The composition of the mineral water solution includes: EDTA·2Na 6.39 mg / L, FeSO4·H2O 5.00 mg / L, H3BO3 0.014 mg / L, ZnSO4·7H2O 0.43 mg / L, CoCl2·6H2O 0.24 mg / L, MnCl2·4H2O 0.99 mg / L, CuSO4·5H2O 0.25 mg / L, NiCl2·6H2O 0.19 mg / L, and Na2MoO4·2H2O 0.22 mg / L.

[0016] Specifically, in the embodiments of the present application, the composite biological system formed by the kaolin and the activated sludge is a composite system obtained by mixing the kaolin and the activated sludge and culturing by SBR periodic operation, and the preparation method specifically comprises the following steps: The activated sludge in the sewage treatment plant is used as the inoculated sludge in the SBR, and the concentration of the inoculated sludge is 3-4 g / L in terms of mixed liquid suspended solid concentration MLSS, and the dosage of the inoculated sludge is 30-100% of the effective reaction volume of the SBR; The nutrient solution required for biological metabolism is injected into the SBR, and continuous circulation operation is carried out, until the ammonia nitrogen in the effluent is <2 mg / L, then kaolin is added to the SBR, mixed, and the nutrient solution required for biological metabolism is continuously injected, and after continuous operation for 25-30 days, a composite biological system formed by kaolin and activated sludge is obtained, wherein: the SBR works in a periodic operation mode, and each operation cycle includes, in turn, a water inlet stage of 3-8 min, an aerobic stirring stage of 200-300 min, a sedimentation stage of 20-40 min, a water discharge stage of 10-30 min and an idle stage of 50-70 min, and the water discharge ratio is 40-60%, the water inlet and outlet amount is equal in each cycle, and the total hydraulic retention time during operation is 8-18 h, the dosage of the kaolin is 1%-1.25% of the dosage of the inoculated sludge. The nutrient solution required for biological metabolism in this embodiment is an aqueous solution of nutrients required for microbial metabolism, preferably, the chemical oxygen demand is 200-300 mg / L, and the ammonia nitrogen is 50-100 mg / L.

[0017] The water inlet CIP and the leaching of metal ions will inhibit the microbial reaction to some extent, and when the activated sludge and the kaolin are mixed in the above proportions, the inhibition on the microorganisms can be greatly avoided or buffered. Specifically, by comparing the removal effects of the microorganisms on the chemical oxygen demand (COD) and the ammonia nitrogen, in terms of COD removal, the effect of adding the kaolin in the above proportions is better, the heterotrophic bacteria activity in the composite biological system is stronger (the COD removal rate of the SBR with 1-1.25% kaolin can be stabilized at about 63.6%, while under the same conditions, the COD removal rate of the system without kaolin or with kaolin in a volume of less than 1% is only about 45.6%, indicating that the addition amount of the kaolin in this interval significantly stabilizes the activity of the heterotrophic bacteria), and the SBR is converted to short-cut nitrification (i.e. the step of nitrite oxidation is inhibited), and the short-cut nitrification is more environmentally friendly than the full nitrification, such as saving aeration, reducing the production of excess sludge, and the high nitrite in the effluent is more easily coupled with anaerobic ammonia oxidation for green denitrification process.

[0018] Specifically, the specific conditions of the aerobic biological reaction in step 2 include: The SBR works in a periodic operation mode, each operation cycle includes water feeding stage for 3-8 min, aerobic stirring stage for 200-300 min, sedimentation stage for 20-40 min, drainage stage for 10-30 min and idle stage for 50-70 min in turn, and the drainage ratio is 40-60%, and the hydraulic retention time is 8-18 h; during the operation, the air pump is used for aeration to provide dissolved oxygen for the activated sludge in the SBR, and the rotor flowmeter is used to maintain the dissolved oxygen at 0.3-3 mg / L; the pH does not need to be deliberately adjusted, and the reaction process is maintained at 7.0-8.0; the temperature is controlled at 20-25℃; and the mechanical stirrer is used to uniformly mix the activated sludge in the SBR.

[0019] Specifically, the preparation method of the biomass charcoal in-situ grown cobalt-molybdenum double-metal composite material includes: The biomass carrier is immersed in a mixed solution containing a cobalt source and a molybdenum source, stirred, evaporated, and calcined to obtain the biomass charcoal in-situ grown cobalt-molybdenum double-metal composite material. Specifically, the biomass carrier is preferably plant bran.

[0020] In a specific embodiment, referring to Figure 1 A method for coupling treatment of antibiotic wastewater, comprising the following steps: A: preparing a biomass charcoal in-situ grown cobalt-molybdenum double-metal composite material, specifically including the following steps: a. Take wheat bran raw materials, sequentially wash with deionized water for 3 times, dry at 60℃ for 24 h, crush with a pulverizer and then pass through a 100-mesh sieve to remove large particle impurities and provide a uniform carrier.

[0021] b. Prepare a mixed solution containing a cobalt source (CoSO4·7H2O) and a molybdenum source ((NH4)6Mo7O 24 ·4H2O), control the molar ratio of Co 2+ and Mo 6+ to be 1:0.3-3 (preferably 1:0.5), so that the concentration of the metal precursor is 6-14 mM (preferably 10 mM); take the pretreated bran carrier and immerse it in the above-mentioned solution, the ratio of the bran carrier to the solution is 0.01-0.02 g / mL, and after magnetic stirring at room temperature for 4 h, evaporate at 80℃; wash with anhydrous ethanol and deionized water alternately until the washing liquid is neutral, and dry at 60℃ c. Place the metal-loaded carrier in a quartz boat in a tube furnace; discharge air by passing N2, and program the temperature (10 ℃ / min) to 400-800℃ (preferably 700℃); constant temperature calcination for 2 h; naturally cool to room temperature.

[0022] d. After grinding, wash the calcined product alternately with deionized water and ethanol until it is neutral, and dry at 60℃ for standby use; B: fixed bed oxidation reaction, specifically including: Referring to Figure 2 The prepared CoMo / WB catalyst particles were uniformly mixed with inert fillers at a mass ratio of 1:2-1:5 and filled into a fixed bed reactor.

[0023] The fixed bed reactor was a cylindrical reactor made of organic glass with an inner diameter of 1-2 cm, a length of 10-20 cm, and filled with inert materials and composite catalysts. The inert materials can be quartz sand or polyurethane sponge; the composite catalyst is CoMo / WB, and the hydraulic retention time (HRT) is 18-30 min. PMS is used to generate free radicals by catalytic reaction with the loaded catalyst to achieve the removal of antibiotics in wastewater. During operation, the fillers are periodically removed, and the catalysts filled inside are flushed by water washing procedure. If the catalytic activity decreases or fails, new catalysts are filled into the fixed bed reactor.

[0024] C: SBR reaction, including: Referring to Figure 3 The SBR is a cylindrical reactor made of organic glass with an inner diameter of 10-15 cm and an effective reaction volume of 1-2 L. Before the entire coupling treatment method is carried out, the inoculated sludge is acclimated: The SBR uses the sludge from the oxidation ditch of an actual wastewater treatment plant as the inoculated sludge. After washing with clean water, the sludge concentration is diluted to 3-4 g / L, and the dosage of the inoculated sludge is 50% of the effective reaction volume of the reactor. The SBR influent is a biological metabolism required nutrient solution prepared with tap water, and the nutrient components include: CH3COONa 320 mg / L, NH4Cl 267 mg / L, KH2PO3 13 mg / L, MgSO4·7H2O 60 mg / L, CaCl2·2H2O 14 mg / L, NaHCO3 1.0 g / L, and 1 mL of a mineral water solution is added to each liter of biological metabolism required nutrient solution. The mineral water solution components include: EDTA·2Na 6.39 mg / L, FeSO4·H2O 5.00 mg / L, H3BO3 0.014 mg / L, ZnSO4·7H2O 0.43 mg / L, CoCl2·6H2O 0.24 mg / L, MnCl2·4H2O 0.99 mg / L, CuSO4·5H2O 0.25 mg / L, NiCl2·6H2O 0.19 mg / L, and Na2MoO4·2H2O 0.22 mg / L. The dissolved oxygen in the SBR is provided by air pumping, and the rotor flow meter controls the dissolved oxygen level in the SBR to be 0.3-3 mg / L, and the pH is maintained at 7.0-8.0; a multifunctional parameter tester is used to monitor the pH change and dissolved oxygen concentration in the SBR; and a mechanical stirrer is used to uniformly mix the activated sludge in the SBR. A complete operation cycle of the SBR includes, in sequence, influent (5 min), aerobic stirring (240 min), sedimentation (30 min), drainage (20 min), and idling (65 min). The drainage ratio is 50%, and under this condition, the SBR is continuously operated until the ammonia nitrogen (NH4 + -N) concentration in the effluent is less than 2 mg / L. Kaolin is added to the SBR reactor as a support for the growth of activated sludge, and the filling ratio of the kaolin is 1%-1.25% of the inoculated sludge dosage of the SBR. The biological metabolism required nutrient solution is continuously injected, and the cycle operation is continued for 28 days according to the above cycle parameters, and then the SBR is stopped to obtain a composite biological system formed by kaolin and activated sludge.

[0025] The effluent from the fixed bed reactor is supplemented with a biological metabolism required nutrient source in the conditioning tank, and then injected into the SBR through a peristaltic pump, the stirrer and air pump are started to uniformly mix the kaolin and activated sludge composite biological system, the rotor flow meter is used to control the dissolved oxygen level in the SBR to be 0.3-3 mg / L, aerobic stirring is performed for 240 min, sedimentation is performed for 30 min for sludge-water separation, supernatant is discharged for 20 min, and idling is performed for 65 min to complete a working cycle.

[0026] In this embodiment, first, the persulfate (PMS) is mixed with the antibiotic wastewater to obtain a mixed solution with a PMS concentration of 0.15-0.9 mM, the mixed solution is introduced into the fixed bed reactor, and the heterogeneous catalytic oxidation reaction is carried out in the fixed bed reactor, so as to degrade the antibiotic and reduce the toxicity of the wastewater. The effluent after the persulfate oxidation treatment is mixed with the nutrient source required for biological metabolism in the intermediate conditioning tank, and the carbon source, nitrogen source and nutrient salt required for biological treatment are supplemented, and then introduced into the aerobic biological treatment device, and the high metabolic capacity of microorganisms is utilized to realize deep mineralization removal of organic pollutants.

[0027] PMS is activated on the surface of the heterogeneous CoMo / WB composite catalyst, without adjusting the pH, to generate sulfate radicals (SO4· - ), superoxide anions (O2· - ) and hydroxyl radicals (·OH) in situ on the surface of the catalyst, which can break the rigid fused ring structure of the antibiotic (such as CIP) into low-toxic small molecules through quinolone ring and piperazine ring opening, and at the same time realize partial mineralization.

[0028] After the effluent (containing small molecule organic matter) of the oxidation stage enters the SBR, the kaolin exchanges the residual metal ions (such as Co 2+ leachate) through Al 3+ / Si 4+ ions, and the layered structure provides attachment sites for microorganisms to form a "kaolin-biofilm" microdomain, accelerate extracellular electron transfer (EET), and strengthen the anti-interference ability of microorganisms to changes in water quality.

[0029] The antibiotic concentration is reduced from 10 mg / L to <0.1 mg / L in the oxidation stage, which ensures that the toxicity of the wastewater entering the SBR is greatly reduced, avoids the collapse of the microbial community structure, and enables the microorganisms in the SBR to normally metabolize and mineralize the remaining small molecule organic matter.

[0030] In a second aspect of the present application, an antibiotic coupled treatment system is provided, which comprises an oxidation reaction device, a conditioning device and an aerobic biological reaction device connected in sequence, as shown in Figure 1 , wherein the oxidation reaction device comprises a fixed bed reactor 1 for carrying out the persulfate oxidation reaction of any one of the above, the conditioning device is used for mixing the wastewater after the oxidation reaction in the fixed bed reactor 1 with the nutrient source required for biological metabolism, and the aerobic biological reaction device comprises a sequencing batch bioreactor 2 for carrying out the aerobic biological reaction of any one of the above.

[0031] Further, the oxidation reaction device further comprises an antibiotic wastewater storage tank 3 and a first peristaltic pump 4, the effluent outlet of the antibiotic wastewater storage tank 3 is connected with the water inlet end of the first peristaltic pump 4, and the water outlet end of the first peristaltic pump 4 is connected with the water inlet of the fixed bed reactor 1.

[0032] Specifically, the adjusting device comprises an adjusting tank 5, a stirrer 6, a second peristaltic pump 7 and a nutrient source reserve tank (not shown in the figure) required for biological metabolism, the water inlet of the adjusting tank 5 is connected with the water outlet of the fixed bed reactor 1 and the discharge port of the nutrient source reserve tank required for biological metabolism respectively, after the water outlet of the fixed bed reactor 1 and the nutrient source required for biological metabolism are mixed uniformly under the action of the stirrer 6, the mixture is injected into the sequencing batch bioreactor 2 through the second peristaltic pump 7. The description of the reaction in each device is described in the above method embodiment, and will not be repeated here.

[0033] (Three) beneficial effects The above technical scheme of the present application has the following beneficial technical effects: The antibiotic wastewater coupling treatment method and system provided by the present application can efficiently activate peroxymonosulfate (PMS) on the surface of a heterogeneous CoMo / WB composite catalyst in a fixed bed reactor, without adjusting the pH value, so that a plurality of active oxygen species, including sulfate radicals (SO4· - ), superoxide anions (O2· - ) and hydroxyl radicals (·OH), can be generated in situ on the surface of the catalyst, and the catalyst does not need to be separated and recovered by a separation unit.

[0034] These high-activity species act on antibiotic molecules (such as CIP) through oxidation reactions, break the quinolone ring and the piperazine ring along the path, gradually disassemble the rigid fused ring structure, and convert the high-toxicity and difficult-to-degrade macromolecules into low-toxicity and easily-biodegradable small-molecule organic matter.

[0035] In this process, part of the organic carbon is oxidized to CO2, realizing partial mineralization, and significantly weakening the toxicity and resistance gene selection pressure of the wastewater.

[0036] After the oxidation stage treatment, the antibiotic concentration is reduced from 5-40 mg / L to <0.1 mg / L, ensuring that the biodegradability of the effluent is significantly improved, and providing a good metabolizable substrate for the subsequent biological stage.

[0037] The effluent (mainly containing small-molecule organic matter and a small amount of metal ions such as Co 2+ ) of the oxidation stage enters the SBR, and the kaolin added in the reactor plays a dual function: on the one hand, through the ion exchange and surface complexation of Al 3+ / Si 4+ ions, the metal ions (such as Co 2+), significantly reducing the toxic effects of metal ions on microorganisms; on the other hand, the layered structure and high specific surface area of kaolin provide attachment sites for microorganisms to grow, promoting the formation of "kaolin-biofilm" microdomains. This microdomain can accelerate the extracellular electron transfer process in the biological system, improve the distribution of electron acceptors, and strengthen the synergistic metabolic capacity between microorganisms, making the system more resistant to water quality fluctuations and more stable.

[0038] In addition, the partial mineralization in the oxidation stage weakens the organic toxicity of the wastewater, allowing the microbial community entering the SBR to maintain stable metabolic activity.

[0039] The heterotrophic bacteria are protected and their metabolic functions are restored, enhancing their ability to absorb and mineralize small-molecule organic matter.

[0040] Finally, the entire system realizes a continuous reaction path of front-end chemical chain breaking and back-end biological mineralization. The front oxidation stage ensures toxicity reduction and degradability improvement, and the back biological stage completes complete mineralization and nitrogen conversion. The synergistic effect of the two makes the overall removal rate of antibiotics (99.6%) and the mineralization rate (68.9%) of the system significantly higher than that of single oxidation or single biological process. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 The schematic diagram of the antibiotic wastewater coupled treatment system provided by the embodiment of the present application is shown in the figure. Figure 2 The schematic diagram of the reaction principle of the fixed bed reactor provided by the embodiment of the present application is shown in the figure. Figure 3 The schematic diagram of the SBR provided by the embodiment of the present application is shown in the figure. Figure 4 The schematic diagram of the CIP removal rate of the treatment method provided by Example 1 and Comparative Examples 1 and 2 of the present application is shown in the figure. Figure 5 The schematic diagram of the TOC removal rate of the treatment method provided by Example 1 and Comparative Example 1 of the present application is shown in the figure.

[0042] Among them: 1, fixed bed reactor, 2, sequencing batch bioreactor, 3, antibiotic wastewater storage tank, 4, first peristaltic pump, 5, adjusting tank, 6, stirrer, 7, second peristaltic pump. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical scheme and advantages of the present application more clear and explicit, the present application will be further described in detail below with reference to the specific embodiments and the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present application. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present application.

[0044] The raw materials and reagents used in the embodiments and comparative examples of the present application are all conventional commercially available products, wherein: The antibiotic wastewater used in the examples and comparative examples is an aqueous solution with a CIP concentration of 10 mg / L; The PMS used in the sulfate oxidation reaction in the examples is a commercially available potassium hydrogen persulfate composite salt (2KHSO 55 ·KHSO4·K2SO4); The kaolin used in the examples is a dry powder kaolin (chemical purity) purchased from Beijing Yuan Ye Biotechnology Co., Ltd., which is directly added when added; The composite catalyst used in the examples is a biomass charcoal in-situ cobalt-molybdenum bimetallic composite material (CoMo / WB), and its preparation method is as follows: a. Take the wheat bran raw material, wash it with deionized water for 3 times, dry at 60°C for 24 h, crush it with a crusher and then pass it through a 100 mesh sieve to remove large particle impurities to obtain a uniform bran carrier.

[0045] b. Prepare a mixed solution containing cobalt source (CoSO4·7H2O) and molybdenum source ((NH4)6Mo7O 24 ·4H2O), control the molar ratio of Co 2+ and Mo 6+ to be 2:1, so that the total metal concentration of the metal precursor is 10 mM; take 1.0 g of the pretreated bran carrier in step a and immerse it in 80 ml of the above solution, magnetically stir at room temperature for 4 h, and then evaporate at 80°C; wash with anhydrous ethanol and deionized water alternately until the washing liquid is neutral, and dry at 60°C; c. Place the metal-loaded carrier obtained in step b in a tube furnace quartz boat; exhaust air with N2, and program the temperature (10°C / min) to 700°C; constant temperature calcination for 2 h; naturally cool to room temperature.

[0046] d. After grinding the calcined product, wash it with deionized water and ethanol alternately until it is neutral, and dry at 60°C for standby use.

[0047] The nutrient solution required for biological metabolism used in the examples and comparative examples is a mixed solution prepared with water (chemical oxygen demand = 250 mg / L, ammonia nitrogen = 70 mg / L), and the nutrient components include: CH3COONa 320 mg / L, NH4Cl 267 mg / L, KH2PO3 13 mg / L, MgSO4·7H2O 60 mg / L, CaCl2·2H2O 14 mg / L, NaHCO3 1.0 g / L, and 1 mL of a mineral water solution is added to each liter of the mixed solution. The mineral water solution components include: EDTA·2Na 6.39 mg / L, FeSO4·H2O 5.00 mg / L, H3BO3 0.014 mg / L, ZnSO4·7H2O 0.43 mg / L, CoCl2·6H2O 0.24 mg / L, MnCl2·4H2O 0.99 mg / L, CuSO4·5H2O 0.25 mg / L, NiCl2·6H2O 0.19 mg / L, Na2MoO4·2H2O 0.22 mg / L. The nutrient source required for biological metabolism used in step 1 of the examples includes nutrient salts and a mineral water solution, and the nutrient salts are directly added to the wastewater after the oxidation reaction in the fixed bed reactor, and 1 mL of the mineral water solution is added to each liter of the wastewater. After addition, the nutrient components and mineral components in the wastewater after the oxidation reaction in the fixed bed reactor are the same as the above-mentioned mixed solution.

[0048] The examples adopt Figure 1 The system is shown in FIG. 1, wherein, referring to Figure 2 The fixed bed reactor is a cylindrical organic glass material, the inner diameter of the fixed bed reactor is 2 cm, and the total volume is 50 mL; referring to Figure 3 The SBR is a cylindrical reactor made of organic glass, the inner diameter is 10 cm, the volume is 2.0 L, the aerobic environment in the SBR is maintained by an air pump, and the rotor flow meter controls the dissolved oxygen level in the SBR; a multifunctional parameter tester is used to monitor the pH change and dissolved oxygen concentration in the SBR; a mechanical stirrer is used to uniformly mix the activated sludge in the SBR; The activated sludge filled in the SBR in the examples is a composite biological system formed by kaolin and activated sludge, and the specific preparation method includes: The inoculated sludge filled in the SBR is taken from the oxidation ditch sludge of the sewage treatment block of the Jiuxianqiao Reclaimed Water Plant in Beijing, and after washing with clean water, the concentration is adjusted to 3 g / L (calculated as the mixed liquor suspended solids concentration), and the inoculated sludge is added in an amount of 50% of the effective reaction volume of the SBR; The nutrient solution required for biological metabolism is injected into the SBR, and the continuous circulation is operated until the ammonia nitrogen in the effluent is less than 2 mg / L, then kaolin is added into the SBR and mixed with the inoculated sludge, and the nutrient solution required for biological metabolism is continuously injected, and after 28 days of periodic operation, a composite biological system formed by kaolin and activated sludge is obtained, wherein the SBR works in a periodic operation mode, each operation cycle includes in succession water inlet stage 5 min, aerobic stirring stage 240 min, sedimentation stage 30 min, water discharge stage 20 min and idle stage 65 min, and the water discharge ratio is 50%; the water inlet and outlet amount is equal per cycle, and the overall hydraulic retention time during operation is 12 h, and the dosage of the kaolin is 1.25% of the dosage of the inoculated sludge. During the operation, the dissolved oxygen is maintained at 0.3-3 mg / L, the pH is 7.0-8.0, and the temperature is controlled at 20-25℃.

[0049] Example 1 The present embodiment provides a method for coupling treatment of antibiotic wastewater, which adopts Figure 1 The system is shown in the figure, comprising the following steps: Step 1: antibiotic wastewater containing 0.5 mM PMS and a flow rate of 1.7 mL / min is injected into the fixed bed reactor 1 for persulfate oxidation reaction, wherein the fixed bed reactor 1 is filled with a mixture of quartz sand and composite catalyst CoMo / WB, the mass ratio of composite catalyst CoMo / WB to quartz sand is 1:2, and the hydraulic retention time HRT is 30 min; Step 2: after the wastewater is oxidized by the fixed bed reactor 1, the required nutrient source for biological metabolism is added in the adjusting tank 6, and after mixing uniformly, it is injected into the sequencing batch reactor 2 for aerobic biological reaction, the rotor flowmeter is used to control the dissolved oxygen level in the SBR to be 0.3-3 mg / L, the pH is 7.0-8.0, and the temperature is controlled at 20-25℃, wherein the SBR works in a periodic operation mode, each operation cycle includes in succession water inlet stage 5 min, aerobic stirring stage 240 min, sedimentation stage 30 min, water discharge stage 20 min and idle stage 65 min, and the water discharge ratio is 50%; the water inlet and outlet amount is equal per cycle, and the overall hydraulic retention time during operation is 12 h. The above method is continuously operated for 14 days, and the effluent CIP and TOC are detected every day, and the results are shown in Figure 4 and 5 .

[0050] Comparative Example 1 The method of step 1 of the example is used to oxidize the antibiotic wastewater, and after 30 min of reaction, the effluent CIP and TOC are detected, and the results are shown in Figure 4 and 5 .

[0051] Comparative Example 2 The SBR used in step 2 of the example was used to treat antibiotic wastewater, and the operation time was 70 days. The CIP of the effluent was detected, and the results are shown in Table 2. Figure 4 and 5 .

[0052] From Figure 4 and 5 It can be seen that the TOC removal ability of Comparative Example 1 for CIP is limited, and a large amount of intermediate products remaining in the wastewater are difficult to further degrade; Comparative Example 2 treats and degrades antibiotic wastewater, and it is difficult to achieve effective degradation of CIP, and the degradation rate of CIP is only 6.0%; the CIP concentration of the effluent of the example is less than 0.1 mg / L, the CIP degradation rate can reach more than 99%, the TOC removal rate is increased by 37.5% (up to 75%), and the stable TOC mineralization effect can still be maintained after fourteen days of continuous operation, and the average removal rate can reach 68.9%. It shows that the method can realize the deep purification and stable mineralization of antibiotic wastewater.

[0053] The catalyst of the application uses agricultural waste wheat bran as a carbon source, and the prices of cobalt and molybdenum precursors are low, without the need for noble metals; it can be formed by one-step calcination, and has a short synthesis route and low energy consumption. The reaction time is short, and the dosages of the catalyst and PMS are reduced.

[0054] It should be understood that the above specific embodiments of the application are only used for illustrative or explanatory purposes of the principles of the application, and do not constitute a limitation on the application. Therefore, any modification, equivalent replacement, improvement, etc. made without departing from the spirit and scope of the application shall be included in the protection scope of the application. In addition, the appended claims of the application are intended to cover all variations and modifications falling within the scope and boundary of the appended claims, or the equivalent forms of such scope and boundary.

Claims

1. A method for coupled treatment of antibiotic wastewater, characterized in that, The method comprises the following steps: Step 1: injecting antibiotic wastewater containing persulfate into a fixed bed reactor for persulfate oxidation, wherein the fixed bed reactor is filled with a composite catalyst and inert fillers, and the composite catalyst is a biomass charcoal in-situ grown cobalt-molybdenum bimetallic composite material; Step 2: mixing the wastewater after the oxidation reaction in the fixed bed reactor with a biological metabolism required nutrient source and then injecting the mixture into a sequencing batch bioreactor for aerobic biological reaction, wherein the sequencing batch bioreactor is filled with a composite biological system formed by kaolin and activated sludge.

2. The treatment method according to claim 1, characterized in that, The antibiotic concentration in the antibiotic wastewater is 5-40 mg / L.

3. The treatment method of claim 1, wherein, The specific conditions of the persulfate oxidation reaction in step 1 include: The dosage concentration of persulfate in the antibiotic wastewater containing persulfate is 0.15-0.9 mM in terms of peroxymonosulfate; The mass ratio of the composite catalyst to the inert fillers is 1:2-5; The hydraulic retention time is 18-30 min.

4. The treatment method of claim 1, wherein The antibiotic concentration in the wastewater after the oxidation reaction in the fixed bed reactor is less than 0.1 mg / L.

5. The treatment method of claim 1, wherein The mixing of the wastewater after the oxidation reaction in the fixed bed reactor with the biological metabolism required nutrient source in step 2 specifically includes: After mixing, the chemical oxygen demand reaches 200-300 mg / L, and the ammonia nitrogen reaches 50-100 mg / L.

6. The treatment method of claim 1, wherein The preparation method of the composite biological system formed by kaolin and activated sludge includes: The activated sludge in a sewage treatment plant is used as the inoculated sludge in the sequencing batch bioreactor, and the concentration of the inoculated sludge is 3-4 g / L in terms of mixed liquor suspended solids, and the dosage of the inoculated sludge is 30-100% of the effective reaction volume of the sequencing batch bioreactor; The nutrient solution required for biological metabolism is injected into the sequencing batch bioreactor, and the sequencing batch bioreactor is continuously circulated until the ammonia nitrogen in the effluent is less than 2 mg / L, then kaolin is added to the sequencing batch bioreactor, mixed, and the nutrient solution required for biological metabolism is continuously injected, and after continuous operation for 25-30 days, the composite biological system formed by kaolin and activated sludge is obtained, wherein: The sequencing batch bioreactor works in a periodic mode, and each operation cycle includes, in sequence, a water inlet stage of 3-8 min, an aerobic stirring stage of 200-300 min, a sedimentation stage of 20-40 min, a drainage stage of 10-30 min, and an idle stage of 50-70 min, and the drainage ratio is 40-60%, and the hydraulic retention time is 8-18 h; the dosage of the kaolin is 1%-1.25% of the dosage of the inoculated sludge.

7. The treatment method of claim 1, wherein The specific conditions of the aerobic biological reaction in step 2 include: The sequencing batch biological reactor works in a periodic operation mode, each operation cycle includes water feeding stage of 3-8 min, aerobic stirring stage of 200-300 min, sedimentation stage of 20-40 min, water discharging stage of 10-30 min and idle stage of 50-70 min in sequence, the water discharging ratio is 40-60%, the hydraulic retention time is 8-18 h, the dissolved oxygen is maintained at 0.3-3 mg / L, the pH is 7.0-8.0, and the temperature is controlled at 20-25 DEG C.

8. The treatment method of claim 1, wherein, The preparation method of the biomass charcoal in-situ grown cobalt-molybdenum bimetallic composite material comprises: The biomass carrier is immersed into a mixed solution containing a cobalt source and a molybdenum source, stirred, evaporated and dried, and calcined to obtain the biomass charcoal in-situ grown cobalt-molybdenum bimetallic composite material.

9. An antibiotic coupling treatment system, characterized by, The method comprises sequentially connecting an oxidation reaction device, an adjusting device and an aerobic biological reaction device, wherein the oxidation reaction device comprises a fixed bed reactor for performing the persulfate oxidation reaction according to any one of claims 1-8, the adjusting device is used for mixing the wastewater after the oxidation reaction in the fixed bed reactor with a nutrient source required by biological metabolism, and the aerobic biological reaction device comprises a sequencing batch biological reactor for performing the aerobic biological reaction according to any one of claims 1-8.

10. The system of claim 1, wherein, The oxidation reaction device further comprises an antibiotic wastewater storage tank and a first peristaltic pump, the water outlet of the antibiotic wastewater storage tank is connected with the water inlet end of the first peristaltic pump, and the water outlet end of the first peristaltic pump is connected with the water inlet of the fixed bed reactor.

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