An antibiotic wastewater pretreatment system and treatment method

Abstract

This invention provides an antibiotic wastewater pretreatment system, comprising: a micro-aeration tank for directly or indirectly treating antibiotic wastewater, the micro-aeration tank having an air inlet, a reagent inlet, and a sludge inlet, the sludge inlet being connected to a residual sludge discharge pipe of a biological treatment system; an intermediate settling tank connected to the micro-aeration tank for treating wastewater I from the micro-aeration tank, the intermediate settling tank also having a sludge return pipe connected to the micro-aeration tank; a reaction tank connected to the intermediate settling tank for treating wastewater II from the intermediate settling tank, the reaction tank also having a flocculant inlet; and a primary settling tank connected to the reaction tank for treating wastewater III from the reaction tank, the primary settling tank having an outlet connected to a subsequent biological treatment system and a sludge outlet. This invention also discloses a method for pretreating antibiotic wastewater, which can effectively reduce the biotoxicity of wastewater and ensure the stable operation of the subsequent biological treatment system; it has the advantages of wide applicability, low operating cost, and high treatment efficiency.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to an antibiotic wastewater pretreatment system and treatment method. By combining multiple technologies, the system achieves detoxification pretreatment of antibiotic wastewater, ensuring the stable operation of subsequent biological wastewater treatment. Background Technology

[0002] Antibiotic wastewater is a type of high-concentration, recalcitrant industrial wastewater characterized by high color, poor biodegradability, and inhibitory or even toxic effects on microorganisms. It is characterized by high COD, total nitrogen, total phosphorus, and salt concentrations (especially sulfates). The inhibitory effect of residual antibiotics on microorganisms is the fundamental reason for the difficulty in treating this wastewater. Antibiotics are chemical substances produced by microbial metabolism that can inhibit or kill other microorganisms at low concentrations. Antibiotics have a strong inhibitory effect on the biological treatment process of wastewater, and the residual antibiotics in the treated wastewater can have potential environmental impacts.

[0003] The main methods for treating antibiotic wastewater include physical, chemical, and biological methods. Physical methods primarily include air flotation, adsorption, and membrane technology; chemical methods mainly include ozone oxidation, Fenton oxidation, and electrochemical technology; biological methods mainly include upflow anaerobic sludge blanket (UASB), sequencing batch reactor (SBR), aerosol bioreactor (A / O), and membrane bioreactor (MBR). Due to its complex composition and high content of toxic substances, antibiotic wastewater cannot achieve stable discharge compliance using a single method. Biological treatment methods are effective and cost-efficient for treating antibiotic wastewater, but due to its toxicity, it is susceptible to load fluctuations or shocks from toxic substances; therefore, effective pretreatment is necessary to improve and enhance the treatment effect.

[0004] The following are some commonly used methods for pretreatment of antibiotic wastewater:

[0005] Air flotation, which includes various forms such as dissolved air flotation, aerated air flotation, chemical air flotation, and electrolytic air flotation, is currently commonly used in China for treating antibiotic wastewater containing antibiotics such as oxytetracycline and gentamicin. However, air flotation suffers from problems such as low removal efficiency, low antibiotic removal rate, and difficulty in dewatering flotation scum.

[0006] Adsorption is a common method for purifying wastewater by using porous solids to adsorb pollutants. A significant advantage of this method is that it does not generate more toxic or recalcitrant pollutants during the removal process. Studies have shown that using activated carbon for intermittent and continuous adsorption of several antibiotic wastewaters, including those containing sulfonamides, trimethoprim, and tetracyclines, achieves antibiotic removal rates between 50% and 95%. While this method is highly efficient at treating antibiotic wastewater, the adsorbed solids become a new pollutant, and the regeneration of the activated carbon is extremely difficult, resulting in very high treatment costs that are difficult for companies to bear.

[0007] Ozone oxidation is a method where ozone, a highly potent oxidizing agent, reacts directly or indirectly with organic matter. Studies have shown that ozone oxidation can achieve antibiotic removal rates of up to 76% in wastewater containing lincomycin, macrolides, quinolones, sulfonamides, and tetracyclines. However, ozone oxidation for wastewater pretreatment involves high equipment investment and operating costs, and stationary catalytic oxidation towers are prone to caking, leading to a rapid decline in treatment efficiency.

[0008] The Fenton oxidation method, using Fenton's reagent (a combination of ferrous salt and H₂O₂), can effectively remove recalcitrant organic matter from antibiotic wastewater. It is commonly used in China for the pretreatment of penicillin and oxytetracycline wastewater. However, the Fenton oxidation method requires repeated pH adjustments and the addition of large amounts of reagent, resulting in high treatment costs. Furthermore, antibiotic wastewater already has a high salt content, and after Fenton pretreatment, the salt content becomes even higher, significantly impacting subsequent biological treatment.

[0009] Electrochemical technology utilizes the electrochemical reaction of organic matter at the anode to remove pollutants from wastewater. Because it does not require the addition of additional flocculants, electrochemical methods offer advantages such as high efficiency, wide applicability, economy, environmental friendliness, and simple operation. However, antibiotic wastewater has a high suspended solids content, which coats the electrodes, reducing electrolysis efficiency. Furthermore, the high hardness of antibiotic wastewater leads to severe scaling at the cathode during electrolysis, causing voltage increases and decreased treatment efficiency. Additionally, electrode passivation further reduces electrolysis efficiency. Therefore, electrochemical technology is difficult to achieve ideal operating results for the pretreatment of antibiotic wastewater.

[0010] Therefore, it is necessary to provide a practical antibiotic wastewater pretreatment system and method to solve the above problems. Summary of the Invention

[0011] To address the aforementioned technical problems, this invention provides an antibiotic wastewater pretreatment system and treatment method. The invention determines whether the antibiotic wastewater will be directly or indirectly introduced into a micro-aeration tank based on its pH value. Specifically, if the antibiotic wastewater has a pH ≤ 5, it enters an iron-carbon tank to generate iron ions before entering the micro-aeration tank; or if the antibiotic wastewater has a pH > 5, it is directly introduced into the micro-aeration tank, where ferrous sulfate is added instead of the iron-carbon tank. Simultaneously, excess sludge from the biological treatment system is also added to the micro-aeration tank. The effluent from the micro-aeration tank then enters an intermediate settling tank, a reaction tank, and a primary settling tank. Sludge from the intermediate settling tank is returned to the micro-aeration tank, and the effluent from the primary settling tank enters the subsequent biological treatment system for further treatment. The sludge settled in the primary settling tank undergoes sludge dewatering.

[0012] The technical means employed in this invention are as follows:

[0013] An antibiotic wastewater pretreatment system includes:

[0014] A micro-aeration tank is used to directly or indirectly treat antibiotic wastewater from a biochemical system. The micro-aeration tank is equipped with an air inlet, a reagent inlet and a sludge inlet. The sludge inlet is connected to the residual sludge discharge pipe of the biochemical system.

[0015] An intermediate settling tank, connected to the micro-aeration tank, is used to treat wastewater I from the micro-aeration tank. The intermediate settling tank is also equipped with a sludge return pipe connected to the micro-aeration tank.

[0016] The reaction tank, connected to the intermediate settling tank, is used to treat wastewater II from the intermediate settling tank. The reaction tank is also equipped with a flocculant inlet.

[0017] A settling tank, connected to the reaction tank, is used to treat wastewater III from the reaction tank. The settling tank is equipped with an outlet and a sludge outlet connected to the subsequent biological treatment system.

[0018] Furthermore, when indirectly treating antibiotic wastewater from a biochemical system, an iron-carbon tank is provided before the micro-aeration tank.

[0019] The present invention also discloses a method for pretreatment of antibiotic wastewater, which uses the above-mentioned antibiotic wastewater pretreatment system for treatment;

[0020] Antibiotic wastewater from the biochemical system is selected to either directly enter the micro-aeration tank or first enter the iron-carbon tank to generate iron ions before entering the micro-aeration tank, depending on its pH value. When entering the micro-aeration tank directly, ferrous sulfate is added from the inlet of the micro-aeration tank to participate in the treatment.

[0021] At the same time, excess sludge from the biological system is added to the micro-aeration tank;

[0022] Wastewater I, treated by the micro-aeration tank, enters the intermediate settling tank. The sludge from the intermediate settling tank is returned to the micro-aeration tank. Wastewater II, treated by the intermediate settling tank, enters the reaction tank. Flocculant is added to the reaction tank. Wastewater III, treated by the reaction tank, enters the primary settling tank. The effluent from the primary settling tank enters the subsequent biological treatment system for further treatment. The sludge settled in the primary settling tank undergoes sludge dewatering treatment.

[0023] Furthermore, when the pH of antibiotic wastewater from the biochemical system is ≤5, it first enters the iron-carbon tank, and after a residence time of 16-24 hours, it enters the micro-aeration tank.

[0024] Furthermore, when the pH of the antibiotic wastewater from the biochemical system is greater than 5, it is directly introduced into the micro-aeration tank, and ferrous sulfate is added to the micro-aeration tank at a concentration of 500–1000 mg / L.

[0025] Furthermore, the aeration rate in the micro-aeration tank is controlled at 0.4–1.0 m³. 3 / h / m 3 .

[0026] Furthermore, the sludge concentration in the micro-aeration tank is controlled at 5000–10000 MLSS mg / L.

[0027] Furthermore, the surface loading of the intermediate settling tank is 1.0–2.0 m³. 3 / (m 2 ·h), the sludge return ratio is (1~2):1.

[0028] Furthermore, the reaction tank adopts a mechanically stirred water flow method with bottom inlet and top outlet, the dosage of flocculant added to the reaction tank is 4-8 mg / L, and the residence time of the reaction tank is 0.5-1 h.

[0029] Furthermore, the surface loading of the settling tank is 0.8–1.0 m³. 3 / (m 2 ·h).

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] 1) The pretreatment system and detoxification method provided by this invention effectively reduce the toxicity of antibiotic wastewater and ensure the stable operation of the subsequent biochemical treatment system.

[0032] 2) Through the adsorption, degradation and sedimentation of sludge, the concentration of wastewater is reduced, and the removal rate of organic matter is very high, reaching 30-50%, which reduces the operating cost of subsequent treatment.

[0033] 3) By adding chemicals and aeration, the problem of odor caused by sulfate reduction during anaerobic processes was solved, the characteristics of the settled sludge were changed, and sludge dewatering was facilitated;

[0034] 4) It also solves the safety problem of anaerobic biogas production, making the operation safer.

[0035] This invention has the advantages of low investment, wide applicability, low operating cost, and high treatment efficiency. Based on the above reasons, this invention has broad market demand and practical promotion value in the field of antibiotic wastewater treatment technology. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of the penicillin wastewater pretreatment system of Embodiment 1 of the present invention.

[0038] Figure 2 This is a schematic diagram of the oxytetracycline wastewater pretreatment system of Embodiment 2 of the present invention.

[0039] Figure 3 The COD removal rate of the pretreatment system under different aeration intensities in Example 2 of this invention is shown.

[0040] In the diagram: 11. Iron-carbon tank; 12. Micro-aeration tank; 13. Intermediate settling tank; 14. Reaction tank; 15. Primary settling tank; ①. Inlet pipe 1; ②. Inlet pipe 2; ③. Sludge return pipe; ④. Outlet pipe; ⑤. Sludge dewatering pipe. Detailed Implementation

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] like Figure 1 and Figure 2 As shown, the present invention provides an antibiotic wastewater pretreatment system, comprising:

[0043] The entry into the iron-carbon tank 11 is determined based on the pH value of the antibiotic wastewater. When the pH of the antibiotic wastewater is ≤5, it enters the iron-carbon tank 11 to generate iron ions, and then enters the micro-aeration tank 12.

[0044] Micro-aeration tank 12 is used to directly or indirectly treat antibiotic wastewater from the biochemical system. When the pH of the antibiotic wastewater is greater than 5, it directly enters the micro-aeration tank 12 and ferrous sulfate is added to replace the iron-carbon tank 11. The micro-aeration tank 12 is equipped with an air inlet, a reagent inlet and a sludge inlet. The sludge inlet is connected to the residual sludge discharge pipe of the biochemical system.

[0045] Intermediate settling tank 13 is connected to the micro-aeration tank 12 and is used to treat wastewater I from the micro-aeration tank 12. The intermediate settling tank 13 is also equipped with a sludge return pipe ③ connected to the micro-aeration tank 12.

[0046] The reaction tank 14 is connected to the intermediate settling tank 13 and is used to treat wastewater II from the intermediate settling tank 13. The reaction tank 14 is also provided with a flocculant inlet.

[0047] A settling tank 15 is connected to the reaction tank 14 and is used to treat wastewater III from the reaction tank 14. The settling tank 15 is equipped with an effluent pipe ④ and a sludge dewatering pipe ⑤ that are connected to the subsequent biochemical treatment system.

[0048] The present invention also discloses a method for pretreatment of antibiotic wastewater, which uses the above-mentioned antibiotic wastewater pretreatment system for treatment.

[0049] Antibiotic wastewater from the biochemical system can be either directly introduced into the micro-aeration tank 12 or first introduced into the iron-carbon tank 11 to generate iron ions before entering the micro-aeration tank 12, depending on its pH value.

[0050] When the pH of antibiotic wastewater from the biochemical system is ≤5, it first enters the iron-carbon tank 11, and after a retention time of 16-24 hours, it enters the micro-aeration tank 12.

[0051] The iron-carbon pool 11 employs "iron catalytic reduction internal electrolysis technology." This method is generally used to target color-producing, recalcitrant, and toxicity-inhibiting substances in synthetic pharmaceutical wastewater, fine chemical wastewater, and coal chemical wastewater. Utilizing the principle of electrochemical catalysis, elemental iron is used to reduce these substances, transforming them into colorless and biodegradable materials. During this process, the generated nascent iron ions also play a role in coagulating and removing some pollutants. Simultaneously, it can remove heavy metals and phosphate ions from the water, improving biological nitrification conditions. This method can decolorize and dechlorinate, achieving high efficiency in removing COD and color from wastewater.

[0052] When the pH of antibiotic wastewater from the biochemical system is greater than 5, the treatment effect of the iron-carbon tank 11 is poor. In this case, the iron-carbon tank 11 can be omitted, and the wastewater can directly enter the micro-aeration tank 12. Ferrous sulfate is added to the micro-aeration tank 12 through the inlet. The amount of ferrous sulfate added to the micro-aeration tank 12 is 500-1000 mg / L. This is because if the pH of the wastewater is adjusted with acid to improve the treatment efficiency of the iron-carbon tank 11, it will increase the operating cost significantly. Furthermore, in order to ensure the alkalinity required for the removal of ammonia nitrogen, liquid alkali will need to be added, making the already high-salt antibiotic wastewater even more difficult to treat and hindering its resource utilization.

[0053] Metallic iron (Fe) has strong reducing properties; the presence of Fe can accelerate the degradation of antibiotics. Simultaneously, Fe... 2+ It can form ternary complexes with the amide and phenolic hydroxyl groups in antibiotic molecules, thus adsorbing the antibiotics. Therefore, antibiotics in wastewater can be degraded and removed after passing through iron-carbon tank 11. The Fe produced in iron-carbon tank 11... 2+ Or Fe in the directly added agent 2+ It can react with S produced by antibiotic wastewater 2- The reaction produces FeS precipitate, which reduces the odor of hydrogen sulfide.

[0054] Furthermore, the main function of the micro-aeration tank 12 is to utilize the action of bacterial hydrolytic enzymes to hydrolyze and acidify the large molecules in antibiotic wastewater into low molecular weight substances, thereby improving the biodegradability of the wastewater and making subsequent biochemical reactions more thorough. Some protein hydrolysis products form polymers with positive and negative charges and coagulation function, which can be used as flocculants. They can destabilize suspended solids and colloidal particles in the water through surface forces, which is conducive to sedimentation and removal.

[0055] The selection of aeration intensity in the micro-aeration tank 12 needs to comprehensively consider the oxygen demand for sludge respiration and the mixed energy consumption oxygen demand of the suspended sludge. The aeration rate is generally controlled between 0.4 and 1.0 m³. 3 / h / m 3 Micro-aeration avoids the anaerobic reduction of sulfates in wastewater, reduces the odor of antibiotic wastewater hydrolysis and acidification, and improves operational safety. At the same time, micro-aeration removes some sugars from antibiotic wastewater and improves the dewatering performance of sludge.

[0056] Meanwhile, excess sludge from the biological system is added to the micro-aeration tank 12; the sludge concentration in the micro-aeration tank 12 is controlled at 5000-10000 MLSS mg / L. In the initial stage of commissioning, excess sludge from the biological system is added to the micro-aeration tank 12 to maintain the sludge concentration. After the micro-aeration tank 12 is running stably, the amount of sludge added can be gradually reduced.

[0057] Wastewater I treated by the micro-aeration tank 12 enters the intermediate settling tank 13. The sludge in the intermediate settling tank 13 is returned to the micro-aeration tank 12 through the sludge return pipe ③. The intermediate settling tank 13 can intercept the sludge and return it to the micro-aeration tank 12, so that the sludge concentration in the micro-aeration tank 12 can be maintained at a relatively high concentration. The surface loading rate of the intermediate settling tank 13 is 1.0~2.0 m3 / (m2·h), and the sludge return ratio is (1~2):1. Setting a larger return ratio can better dilute the antibiotic wastewater at the inlet end, and the treatment effect is more stable.

[0058] The micro-aeration tank 12 makes full use of the adsorption effect of activated sludge to adsorb recalcitrant and toxic substances in wastewater, which are then removed by sedimentation in the primary settling tank 15, ensuring the stable operation of the biological system.

[0059] Wastewater II treated in intermediate settling tank 13 enters reaction tank 14. The reaction tank 14 is mechanically stirred and adopts a bottom-in, top-out water flow method. Flocculant is added to the reaction tank 14 for flocculation reaction. PAM is preferred as the flocculant. The dosage of PAM is 4-8 mg / L. The residence time in the reaction tank is 0.5-1 h.

[0060] Wastewater III, treated in reaction tank 14, enters primary settling tank 15, where the surface loading rate is 0.8–1.0 m³. 3 / (m 2 The effluent from the primary sedimentation tank 15 enters the subsequent biological treatment system through the effluent pipe ④ for further treatment. The sludge settled in the primary sedimentation tank 15 is dewatered through the sludge dewatering pipe ⑤.

[0061] Example 1

[0062] like Figure 1 As shown, this is a wastewater treatment plant of a pharmaceutical factory. The company mainly produces penicillin, 6APA, amoxicillin, and avermectin.

[0063] This embodiment is a pretreatment system for a wastewater treatment device, mainly used to treat penicillin wastewater.

[0064] The penicillin wastewater, with a pH of approximately 4-5, enters the iron-carbon tank 11 through inlet pipe 1①, where the retention time is 24 hours. The effluent from the iron-carbon tank 11 enters the micro-aeration tank 12. Simultaneously, filter cloth washing wastewater also enters the micro-aeration tank 12 through inlet pipe 2②. The micro-aeration tank 12 is equipped with 20 sets of HS high-pressure aerators, and the aeration rate is controlled at 1.0 m³ / s. 3 / h / m 3The retention time in the micro-aeration tank 12 is 32 hours, the sludge concentration in the micro-aeration tank 12 is 10000 mg / L, and the sludge return ratio R1 is 0.5:1. The sludge return ratio R2 in the intermediate settling tank 13 is 2:1. The surface loading rate of the intermediate settling tank 13 is 1.0 m³. 3 / (m 2 The residence time in reaction tank 14 is 1 hour, and it is equipped with a frame-type agitator with a power of 2.2 kW. The surface loading of the primary settling tank 15 is 0.8 m². 3 / (m 2 ·h), the subsequent sludge dewatering equipment adopts a belt filter press.

[0065] The influent COD of penicillin waste acid water is 18,000 mg / L, the influent COD of filter cloth washing wastewater is 5,000 mg / L, the average influent COD is 16,000 mg / L, and the effluent COD after pretreatment is 7,000-8,000 mg / L. The actual COD removal rate of pretreatment is about 30%.

[0066] Example 2

[0067] like Figure 2 As shown, in a centralized wastewater treatment plant, the pretreatment system mainly treats oxytetracycline wastewater.

[0068] The oxytetracycline wastewater, with a pH of approximately 5-6, enters the micro-aeration tank 12 through inlet pipe 1①. Ferrous sulfate is added to the micro-aeration tank 12. The micro-aeration tank 12 is equipped with 180 sets of HS high-pressure aerators, and the aeration rate is controlled at 0.7 m³ / s. 3 / h / m 3 The retention time in the micro-aeration tank 12 is 120 hours, and the sludge concentration in the micro-aeration tank is 8000 mg / L. Once operation is stable, no further sludge will be added. The sludge return ratio R in the intermediate settling tank 13 is 2:1. The surface loading rate of the intermediate settling tank 13 is 1.0 m³. 3 / (m 2 The residence time in reaction tank 14 is 1 hour, and it is equipped with a frame-type agitator with a power of 4.0 kW. The surface loading of the primary settling tank 15 is 1.0 m³. 3 / (m 2 ·h), the subsequent dewatering equipment uses a plate and frame diaphragm filter press.

[0069] The influent COD of oxytetracycline wastewater is 17,000 mg / L, and the influent SS is 1,000 mg / L. After pretreatment, the effluent COD is 8,000–10,000 mg / L, and the effluent SS is <150 mg / L. The COD removal rate of the pretreatment is about 40–50%.

[0070] like Figure 3The figure shows the COD removal rate of the pretreatment system under different aeration intensities in Example 2. It can be seen from the figure that when the aeration rate of the micro-aeration tank is between 0.4 and 1.0 m³ / s... 3 / h / m 3 During this period, as the aeration rate increased, the COD removal rate of the pretreatment system also gradually increased. When the aeration rate was 0.7 m³ / s... 3 / h / m 3 When the aeration rate is increased, the COD removal rate increases slowly because increasing the aeration rate will correspondingly increase the operating power cost. Therefore, the optimal aeration intensity in the micro-aeration tank in Example 2 is 0.7 m³ / s. 3 / h / m 3 .

[0071] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for pretreatment of antibiotic wastewater, characterized in that, An antibiotic wastewater pretreatment system is used to treat antibiotic wastewater from the biochemical system; The antibiotic wastewater pretreatment system includes: A micro-aeration tank is used for the direct or indirect treatment of antibiotic wastewater. The tank is equipped with an air inlet, a reagent inlet, and a sludge inlet, the sludge inlet being connected to the waste sludge discharge pipe of the biological treatment system. When indirectly treating antibiotic wastewater, an iron-carbon tank is installed before the micro-aeration tank. The aeration rate within the micro-aeration tank is controlled at 0.4–1.0 m³ / s. 3 / h / m 3 ; An intermediate settling tank, connected to the micro-aeration tank, is used to treat wastewater I from the micro-aeration tank. The intermediate settling tank is also equipped with a sludge return pipe connected to the micro-aeration tank. The reaction tank, connected to the intermediate settling tank, is used to treat wastewater II from the intermediate settling tank. The reaction tank is also equipped with a flocculant inlet. A settling tank, connected to the reaction tank, is used to treat wastewater III from the reaction tank. The settling tank is equipped with an outlet and a sludge outlet connected to the subsequent biological treatment system. Antibiotic wastewater from the biochemical system is either directly introduced into the micro-aeration tank or first introduced into the iron-carbon tank to generate ferrous ions before entering the micro-aeration tank, depending on its pH value. Specifically, when the pH of the antibiotic wastewater is ≤5, it first enters the iron-carbon tank and then enters the micro-aeration tank after a residence time of 16–24 hours; when the pH of the antibiotic wastewater is >5, it directly enters the micro-aeration tank, and ferrous sulfate is added to the micro-aeration tank through the inlet for treatment. The dosage of ferrous sulfate added is 500–1000 mg / L. At the same time, excess sludge from the biological system is added to the micro-aeration tank; Wastewater I, treated by the micro-aeration tank, enters the intermediate settling tank. The sludge from the intermediate settling tank is returned to the micro-aeration tank. Wastewater II, treated by the intermediate settling tank, enters the reaction tank. Flocculant is added to the reaction tank. Wastewater III, treated by the reaction tank, enters the primary settling tank. The effluent from the primary settling tank enters the subsequent biological treatment system for further treatment. The sludge settled in the primary settling tank undergoes sludge dewatering treatment.

2. The method for pretreatment of antibiotic wastewater according to claim 1, characterized in that, The sludge concentration in the micro-aeration tank is controlled at 5000-10000 MLSS mg / L.

3. The method for pretreatment of antibiotic wastewater according to claim 1, characterized in that, The surface loading of the intermediate settling tank is 1.0–2.0 m. 3 / (m 2 •h), the sludge return ratio is (1~2):

1.

4. The method for pretreatment of antibiotic wastewater according to claim 1, characterized in that, The reaction tank adopts a mechanical stirring and bottom-in, top-out water flow method. The dosage of flocculant added to the reaction tank is 4-8 mg / L, and the residence time of the reaction tank is 0.5-1 h.

5. The method for pretreatment of antibiotic wastewater according to claim 1, characterized in that, The surface loading of the settling tank is 0.8–1.0 m. 3 / (m 2 •h).

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