Method for treating sulfamethoxazole wastewater by using anaerobic membrane bioreactor

Abstract

The invention discloses a method for treating sulfamethoxazole wastewater by using an anaerobic membrane bioreactor. The method comprises the following steps: utilizing an anaerobic membrane bioreactor, externally connecting an air pump to maintain sufficient mixing of sludge and water, internally arranging a flat membrane component, inoculating anaerobic sludge into the reactor, pumping SMX wastewater from the bottom of the reactor, and upwards flowing through the reactor under an anaerobic condition, organic matters in the wastewater are jointly degraded through anaerobic metabolism of microorganisms and adsorption of a biological membrane, and a carbon-sulfur conversion reaction is carried out, so that COD (Chemical Oxygen Demand), sulfate and SMX in the wastewater are efficiently removed. The method is simple and convenient to operate, controllable in process and suitable for treatment of SMX wastewater with different concentrations, and a feasible technical scheme is provided for industrial treatment of antibiotic wastewater.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a method for treating sulfamethoxazole wastewater using an anaerobic membrane bioreactor. Background Technology

[0002] With the widespread use of antibiotics in medical treatment, pharmaceuticals, aquaculture, and industrial production, large quantities of antibiotics and their metabolites enter the environment through wastewater discharge, causing water pollution and potential public health risks. Sulfamethoxazole, a commonly used sulfonamide antibiotic, is widely present in industrial and medical wastewater; its residues can inhibit microbial activity and reduce the stability and efficiency of wastewater treatment systems.

[0003] Recent research by Jia et al. has shown that under certain organic loads and COD / SO4 ratios... 2- Under the same conditions, UASB can achieve organic matter degradation and a certain degree of sulfamethoxazole (SMX) removal. However, its treatment process is greatly affected by high sulfate concentration and antibiotic toxicity, and the removal efficiency fluctuates significantly. Moreover, the system is not adaptable to high concentrations of SMX, indicating that UASB has a significant performance bottleneck in treating high-concentration antibiotic wastewater (JIA Y, KHANAL SK, ZHANG H, et al. Sulfamethoxazole degradation in anaerobic sulfate-reducing bacteria sludge system[J]. Water Research, 2017, 119: 12-20.).

[0004] Anaerobic membrane bioreactors (AnMBRs) have become an ideal technology for treating high-concentration organic wastewater and antibiotic wastewater due to their advantages such as low energy consumption, low sludge production, and high organic matter removal efficiency. However, in the treatment of SMX wastewater, the anaerobic membrane bioreactor system still has the following problems: (1) Decreased wastewater treatment efficiency: The inhibitory effect of high concentration of SMX on the microbial community reduces the COD removal rate, hinders the carbon-sulfur conversion process, and reduces the sulfate reduction efficiency; (2) Limited antibiotic degradation: The high concentration of residual SMX can inhibit the activity of key functional microorganisms (such as sulfate-reducing bacteria and methanogens), resulting in low SMX removal efficiency and difficulty in achieving stable degradation of antibiotics in wastewater; (3) Insufficient optimization of operating conditions: When treating antibiotic wastewater of different concentrations, the existing AnMBR technology mostly adopts fixed operating parameters and lacks system optimization schemes for different SMX concentrations, making it difficult to improve the SMX degradation efficiency while ensuring high COD and sulfate removal rates. Summary of the Invention

[0005] The purpose of this invention is to provide a method for treating sulfamethoxazole wastewater using an anaerobic membrane bioreactor. This method achieves efficient wastewater treatment and carbon-sulfur conversion in the AnMBR system at different SMX concentrations by adjusting the influent conditions and operating parameters.

[0006] The technical solution for achieving the objective of this invention is as follows:

[0007] A method for treating sulfamethoxazole wastewater using an anaerobic membrane bioreactor includes the following steps:

[0008] An anaerobic membrane bioreactor is used, with an external air pump to maintain thorough mixing of sludge and water. An internal flat-sheet membrane module is equipped, and anaerobic sludge is inoculated into the reactor. SMX wastewater is pumped into the reactor from the bottom. Under anaerobic conditions, it flows upward through the reactor. The organic matter in the wastewater is degraded by the anaerobic metabolism of microorganisms and the adsorption of the biofilm, and carbon and sulfur conversion reactions are carried out, achieving efficient removal of COD, sulfate and SMX from the wastewater.

[0009] Furthermore, in the SMX wastewater, COD ≥ 1500 mg / L and sulfate ≥ 750 mg / L

[0010] Furthermore, the carbon-to-sulfur ratio of the influent was adjusted to 2:1.

[0011] Furthermore, the air pump flow rate is 3 L / min.

[0012] Furthermore, the inoculation concentration of anaerobic sludge is 10~20 g / L.

[0013] Furthermore, in the SMX wastewater, the SMX concentration is 0 mg / L to 5 mg / L, but not 0 mg / L.

[0014] Furthermore, the reactor temperature was maintained at 35±1 ℃, and the hydraulic retention time was 24~36 hours.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] (1) While UASB reactors can remove antibiotics such as sulfamethoxazole (SMX) to a certain extent when treating pharmaceutical wastewater, their removal efficiency decreases significantly when the influent concentration is high or the reaction conditions are not optimized. Furthermore, the system stability is poor, making it difficult to maintain high-efficiency operation under high-concentration antibiotic pollution for extended periods. In contrast, this invention employs an anaerobic membrane bioreactor, achieving efficient synergistic removal of COD, sulfate, and high-concentration SMX through long-term microbial retention, maintenance of high sludge concentration, and dynamic optimization of operating parameters. This overcomes the performance bottleneck of traditional UASB systems in treating high-antibiotic wastewater.

[0017] (2) This invention employs an anaerobic membrane bioreactor. The membrane module can retain microorganisms and prevent them from being lost with the effluent, thereby maintaining a high sludge concentration (MLSS) within the reactor. The highly active sludge provides a long-term stable growth environment for key functional bacteria, and the microorganisms can still maintain a certain level of activity even under high-concentration SMX wastewater conditions. This characteristic not only enhances the microorganisms' tolerance to SMX but also improves the stability of the system during long-term operation, enabling the reactor to continuously maintain efficient COD removal, sulfate reduction, and SMX degradation functions.

[0018] (3) When using AnMBR to treat SMX wastewater with concentrations below medium, the removal rates of COD, sulfate, and SMX in the reactor can all reach approximately 90%. This high removal rate is due to the advantages of the membrane module in maintaining microbial retention and high sludge concentration, allowing sufficient contact time for SMX to be biodegraded by functional bacteria. Meanwhile, under high SMX concentrations (e.g., 10 mg / L), the activity of some microorganisms is inhibited, and the removal efficiency decreases, but a certain degree of SMX degradation can still be achieved through optimization of operating parameters (e.g., extending HRT, adjusting pH, and supplementing carbon sources). Compared to traditional UASB reactors, AnMBR has significant advantages under high-concentration antibiotic wastewater conditions.

[0019] (4) This invention can simultaneously and efficiently remove COD, sulfate, and SMX, achieving synergistic treatment of multiple pollutants. The stable microbial community in the reactor supports the carbon-sulfur conversion process, that is, the anaerobic degradation of organic matter and the sulfate reduction reaction occur simultaneously. At low to moderate SMX concentrations, the system can ensure the stability of the carbon-sulfur conversion process; under high SMX concentrations, although microbial activity decreases, carbon-sulfur conversion and partial SMX degradation can still be maintained through optimization of operating parameters, ensuring the overall efficiency and stability of wastewater treatment.

[0020] (5) This invention allows for precise control of the AnMBR system by adjusting operating parameters such as hydraulic retention time (HRT), reactor temperature, pH value, and carbon source addition. Different operating strategies can be adopted for SMX wastewater of different concentrations: for example, maintaining the standard HRT under low concentration conditions can achieve efficient removal, while appropriately extending the HRT and increasing the carbon source or trace element supplementation under high concentration conditions can improve microbial activity and removal efficiency. This operational flexibility allows the reactor to adapt to different antibiotic wastewater treatment needs, ensuring the stability and controllability of the system in industrial applications. Attached Figure Description

[0021] Figure 1 The graph shows the changes in COD removal rate of the AnMBR reactor under different SMX concentrations in Examples 1-4.

[0022] Figure 2The graph shows the changes in sulfate reduction rate in the AnMBR reactor under different SMX concentrations in Examples 1-4.

[0023] Figure 3 The graph shows the variation of SMX removal efficiency of the AnMBR reactor under different SMX concentrations in Examples 1-4. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings.

[0025] A method for treating sulfamethoxazole wastewater using an anaerobic membrane bioreactor includes the following steps:

[0026] (1) Construction of AnMBR reactor

[0027] An anaerobic membrane bioreactor with an effective volume of 2.0 L was constructed and equipped with a flat sheet membrane module to maintain the stability of the microbial community and hydraulic circulation. Anaerobic sludge was added to the reactor to provide a stable growth environment for the microorganisms. The total operation cycle of the reactor was 140 days, during which the system performance was evaluated by monitoring the removal efficiency of COD, sulfate, and SMX.

[0028] (2) Wastewater inflow and reaction conditions

[0029] Synthetic wastewater was prepared with the following composition: COD 1500 mg / L, sulfate 750 mg / L, NH4Cl 110 mg / L, K2HPO3 42 mg / L, and SMX. The wastewater was pumped from the bottom of the reactor and flowed upwards. Microorganisms degraded the organic matter in the wastewater through anaerobic metabolism and carried out carbon-sulfur conversion reactions. The influent SMX concentration gradient was set to 0 mg / L, 0.5 mg / L, 5 mg / L, and 10 mg / L to simulate different antibiotic pollution levels. The influent COD was 1500 mg / L, and the sulfate concentration was 750 mg / L. The reactor temperature was maintained at 35±1℃, and the hydraulic retention time was 24 hours. The pH was adjusted to 7.2±0.2 using sodium bicarbonate, and trace elements were supplemented to ensure normal microbial growth.

[0030] (3) Monitoring and analysis of wastewater removal performance

[0031] During operation, effluent samples are collected periodically to determine COD removal rate, sulfate removal rate, and SMX removal rate. SMX and its degradation products are analyzed by high performance liquid chromatography (HPLC) or mass spectrometry (LC-MS) to evaluate the system removal efficiency under different SMX concentrations. Based on the monitoring results, HRT, temperature, and stirring rate can be adjusted to optimize the removal efficiency of COD, sulfate, and SMX, and ensure the stable operation of the AnMBR system under different antibiotic concentrations.

[0032] Example 1

[0033] Using the above method, the influent SMX concentration was set to 0 mg / L, and the reactor was operated for 70 days. The results are as follows: Figures 1-3 As shown, the COD removal rate is approximately 99%, the sulfate removal rate is approximately 95%, the system exhibits stable carbon and sulfur conversion, and the wastewater treatment effect is good. The COD and sulfate removal efficiencies are the highest, and the microbial activity is normal.

[0034] Example 2

[0035] Using the above method, the influent SMX concentration was adjusted to 0.5 mg / L, and the reactor was operated for 29 days. The results are as follows: Figures 1-3 As shown, the COD removal rate was approximately 95%, the sulfate removal rate was approximately 90%, the SMX removal rate was approximately 90%, and a variety of intermediate metabolites were detected. The microbial activity was stable, and the carbon-sulfur conversion efficiency was good.

[0036] Example 3

[0037] Using the above method, the influent SMX concentration was adjusted to 5 mg / L, and the reactor continued to operate for 26 days. The results are as follows: Figures 1-3 As shown, the COD removal rate is about 80%, the sulfate removal rate is about 78%, the SMX removal rate is about 50%, intermediate metabolites are detectable, and microbial activity has decreased, but the reactor as a whole still maintains relatively stable operation.

[0038] Example 4

[0039] Using the above method, the influent SMX concentration was adjusted to 10 mg / L, and the reactor continued to operate for 22 days. The results are as follows: Figures 1-3 As shown, the COD removal rate is about 70%, the sulfate removal rate is about 68%, and the SMX removal rate is about 10%. Most of the SMX remains, the microbial activity is significantly inhibited, and the carbon-sulfur conversion efficiency decreases. However, the system can still maintain basic operation by adjusting the operating parameters.

Claims

1. A method for treating sulfamethoxazole wastewater using an anaerobic membrane bioreactor, characterized in that, Includes the following steps: An anaerobic membrane bioreactor is used, with an external air pump to maintain thorough mixing of sludge and water. An internal flat-sheet membrane module is equipped, and anaerobic sludge is inoculated into the reactor. SMX wastewater is pumped into the reactor from the bottom. Under anaerobic conditions, it flows upward through the reactor. The organic matter in the wastewater is degraded by the anaerobic metabolism of microorganisms and the adsorption of the biofilm, and carbon and sulfur conversion reactions are carried out, achieving efficient removal of COD, sulfate and SMX from the wastewater.

2. The method according to claim 1, characterized in that, In SMX wastewater, COD ≥ 1500 mg / L and sulfate ≥ 750 mg / L.

3. The method according to claim 1, characterized in that, Adjust the carbon-to-sulfur ratio of the influent to 2:

1.

4. The method according to claim 1, characterized in that, The air pump flow rate is 3 L / min.

5. The method according to claim 1, characterized in that, The inoculation concentration of anaerobic sludge is 10~20 g / L.

6. The method according to claim 1, characterized in that, In SMX wastewater, the concentration of SMX is 0 mg / L to 5 mg / L, but not 0 mg / L.

7. The method according to claim 1, characterized in that, The reactor temperature was maintained at 35±1 ℃, and the hydraulic retention time was 24~36 hours.

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