Microbial electrochemical method and device for removing sulfonamide compounds in wastewater and recovering nitrogen resources

Abstract

The invention discloses a microbial electrochemical method and device for removing sulfonamide compounds in wastewater and recovering nitrogen resources. The device comprises a pool body, and an anode chamber and a cathode chamber which are formed by separating the interior of the pool body through a cation exchange membrane; an anode is arranged in the anode chamber, and a cathode is arranged in the cathode chamber; the anode and the cathode are connected with a power supply for applying constant potential; the anode chamber is used for treating wastewater containing sulfanilamide compounds and nitrate under an anoxic or micro-aerobic condition; the cathode chamber is filled with a cathode solution containing NaCl and a phosphate buffer solution, and the cathode chamber can realize spontaneous alkali production and ammonia recovery. According to the method, while efficient degradation of sulfonamide compounds is enhanced, nitrate nitrogen is directionally converted into recoverable ammonium nitrogen, and finally the synergistic target of removal of pharmaceutical wastewater composite pollutants and recycling of nitrogen is achieved.

Description

Technical Field

[0001] This invention belongs to the field of wastewater technology, and in particular relates to a microbial electrochemical method and apparatus for removing sulfonamide compounds from wastewater and recovering nitrogen resources. Background Technology

[0002] Effective removal of antibiotics is a crucial step in the treatment of pharmaceutical wastewater. Sulfonamide antibiotics, due to their stable chemical structure, are not easily degraded by traditional treatment methods, and high concentrations (μg / L) are frequently detected in water bodies. Simultaneously, high nitrate pollution in pharmaceutical wastewater leads to eutrophication, exacerbating the difficulty of water treatment. However, conventional treatment processes (physicochemical and biochemical methods) cannot effectively remove the complex pollutants in water bodies under high-energy-consuming and long-term operating conditions. Furthermore, the potential nitrogen resources in the water are emitted as strong greenhouse gases—nitrogen oxides—during denitrification, failing to effectively treat the wastewater and further exacerbating air pollution problems. Therefore, developing efficient removal and resource recovery technologies for sulfonamide antibiotics in pharmaceutical wastewater is of great significance.

[0003] Microbial electrochemical technologies (METs) exhibit significant advantages in the mineralization of recalcitrant organic matter and the targeted recovery of nitrogen due to their unique electroactive microbial community synergistic metabolic mechanism. In a microbial electrochemical system (MES), organic matter is oxidized and decomposed by microorganisms at the anode, generating electrons that are then transported to the cathode under the drive of an external potential, or undergo reduction reactions with other electron acceptors (such as nitrates), thereby achieving efficient degradation of pollutants.

[0004] In microbial electrochemical systems, nitrates exhibit unique advantages as key electron acceptors. By enhancing the system's electron transfer efficiency, nitrates provide ample energy and reaction kinetics for the biotransformation of sulfonamides, promoting the breaking and mineralization of their recalcitrant structures such as benzene rings and heterocycles, thus significantly improving the removal efficiency of sulfonamides. Furthermore, this nitrate reduction process is not the traditional denitrification (where products are lost as gaseous nitrogen N2 and N2O, wasting resources and exacerbating the greenhouse effect), but rather utilizes the dissimilatory reduction of nitrates to ammonium (DNRA) pathway, converting inorganic nitrates in wastewater into recyclable ammonium nitrogen.

[0005] The organic nitrogen released during the degradation of SMX can also participate in the transformation simultaneously, ultimately realizing the dual resource utilization process of organic nitrogen in SMX and inorganic nitrogen in wastewater, providing an efficient solution for the synergistic treatment of pharmaceutical wastewater by "pollutant removal and resource recovery".

[0006] Therefore, in response to the problem of high concentrations of sulfonamide antibiotics and nitrate pollution in pharmaceutical wastewater, it is urgent to develop optimized strategies for dynamically regulating microbial activity. By constructing a microbial electrochemical system that introduces nitrate as a multi-electron acceptor, the directional conversion of sulfonamide compounds and nitrates can be enhanced, thereby achieving the harmless treatment and resource utilization of pharmaceutical wastewater.

[0007] The long-term coexistence of sulfonamide antibiotics (such as sulfonamide compounds) and nitrates in pharmaceutical wastewater poses a significant challenge to wastewater treatment. Nitrates, acting as electron acceptors, preferentially compete with readily degradable carbon sources for electron donors, significantly weakening the ability of microorganisms to degrade structurally stable antibiotics. This results in low synergistic removal efficiency, further increasing the difficulty of water treatment. Summary of the Invention

[0008] In view of this, the present invention aims to propose a microbial electrochemical method and device for removing sulfonamide compounds from wastewater and recovering nitrogen resources, in order to solve the problem that existing research mostly focuses on the degradation optimization of single pollutants, and there is still a lack of synergistic treatment mechanisms and technical solutions for this type of complex pollution, which makes it difficult to solve the core bottleneck in actual wastewater treatment.

[0009] To this end, this invention proposes a treatment method that couples microbial electrolysis technology with the DNRA process: using the pollutants in the wastewater (antibiotics as carbon source and nitrates as electron acceptors) as the carbon source and energy required for metabolism, while enhancing the efficient degradation of sulfonamide compounds, nitrate nitrogen is directionally converted into recyclable ammonium nitrogen, ultimately achieving the synergistic goal of removing composite pollutants from pharmaceutical wastewater and recovering nitrogen resources.

[0010] To achieve the above objectives, the technical solution of the present invention is implemented as follows: A microbial electrochemical method and apparatus for removing sulfonamide compounds from wastewater and recovering nitrogen resources includes a tank, an anode chamber and a cathode chamber separated by a cation exchange membrane within the tank; An anode is provided in the anode chamber, and a cathode is provided in the cathode chamber; the anode and cathode are connected to a power source for applying a constant potential; The anode chamber treats wastewater containing sulfonamides and nitrates under anoxic or micro-oxygen conditions; The cathode chamber is filled with a cathodic solution containing NaCl and phosphate buffer, enabling spontaneous alkali production and ammonia recovery.

[0011] Furthermore, the power supply applies a constant potential to the system from -0.4V to 0V; Microorganisms capable of degrading sulfonamide compounds are attached to the anode.

[0012] Furthermore, both the anode and cathode are carbon-based material electrodes, which are selected from graphite felt, carbon brush, or graphite rod.

[0013] Furthermore, the anode chamber is connected to an anode inlet / outlet pipe, which is connected to a first three-way valve; The cathode chamber is connected to a cathode inlet / outlet pipe, which is connected to a second three-way valve.

[0014] A microbial electrochemical method for removing sulfonamide compounds from wastewater and recovering nitrogen resources, using the aforementioned microbial electrochemical device for removing sulfonamide compounds from wastewater and recovering nitrogen resources, includes the following steps: S1: Add co-metabolite carbon source, nitrate, sulfonamide compounds and wastewater to the anode chamber, and introduce nitrogen gas to remove dissolved oxygen into the anode chamber. Add catholyte to the cathode chamber and apply a constant potential to start the system. Subsequently, fix the influent nitrate concentration and operate in a sequential batch mode. Increase the carbon-nitrogen ratio by gradually increasing the amount of co-metabolite carbon source added. Operate under each carbon-nitrogen ratio condition until the system performance is stable and the microbial acclimatization is completed. S2: During the stable operation phase after domestication, the microorganisms in the anode chamber degrade sulfonamide compounds and convert organic nitrogen into inorganic ammonia nitrogen, while reducing nitrate to produce ammonium ions; the generated ammonium ions migrate to the cathode chamber and are converted into ammonia, and nitrogen is recovered by replacing the catholyte.

[0015] Furthermore, sulfonamide compounds include one or more of sulfadiazine, sulfamethoxazole, sulfadiazine, sulfathiazole, sulfadimidine, sulfamethoxypyrimidine, and sulfachlorpyridazine.

[0016] The co-metabolic carbon source in step S1 includes one or more of glucose, acetate, and lactate.

[0017] Furthermore, in the anode chamber of step S1, the dosage of sulfonamide compounds, nitrate nitrogen, and co-metabolic carbon source meets the requirements for the influent chemical oxygen demand (COD) and nitrate nitrogen (NO3). - The mass ratio of -N is controlled between 5 and 9.

[0018] Furthermore, the carbon-nitrogen ratio regulation in step S1 adopts a step-by-step increase strategy, sequentially increasing the COD / NO3 ratio. - The -N ratio was controlled at 5, 7, and 9 for acclimatization, and each stage was operated stably for at least 3 cycles.

[0019] Furthermore, the sequential batch operation in step S1 is carried out in a cycle of 5-10 days; at the end of the cycle, 70%-90% of the liquid in the anode chamber is replaced, and 10%-30% of the mixed solution is retained as the inoculum; the cathode chamber is completely replaced.

[0020] Furthermore, step S1 also includes pretreatment of the anode and cathode before system startup. The pretreatment method includes activating them by soaking in dilute hydrochloric acid solution and then rinsing them clean with deionized water. Step S1 also includes pretreatment of the cation exchange membrane before system startup. The pretreatment method includes soaking it in a saturated sodium chloride solution for 20-28 hours and then soaking it in deionized water for 20-28 hours.

[0021] This invention achieves effective removal and nitrogen form conversion of sulfonamide compounds in pharmaceutical wastewater through a progressive mechanism of "cometabolite substrate domestication—electrode-microbial synergy." Compared with existing technologies, this invention innovatively constructs a multi-electrode electron acceptor system with nitrate as the core, synergistically utilizing the carbon and nitrogen components of sulfonamide compounds in wastewater to build a self-sustaining reaction system of "pollutant carbon source supply—nitrate electron capture—electrochemical energy drive," significantly improving the system's degradation efficiency of sulfonamide compounds and the directionality of nitrogen conversion, ensuring operational efficiency.

[0022] Compared with existing technologies, the microbial electrochemical method and apparatus for removing sulfonamide compounds and recovering nitrogen resources from wastewater described in this invention have the following advantages: 1) This invention enhances SMX removal and nitrate conversion by constructing a serum bottle system and screening for optimal co-metabolizing substrates. In the serum bottle system, the lactate co-metabolizing reactor achieved an SMX degradation rate of 65.76% and a nitrate conversion rate of 84.42% in the steady-state phase, which is approximately 1.8 times that of glucose (35.94%, 45.72%) and acetate (38.16%, 52.53%) under the same conditions.

[0023] (2) This invention constructs a microbial electrochemical system with weak electrical intervention. By introducing nitrate as a multi-electron acceptor, it achieves the simultaneous removal of complex pollutants and realizes the directional transformation of pollutants by cultivating highly efficient electroactive bacterial communities. In the lactate co-metabolism system, the SMX degradation rate is increased to 83.03%, with a maximum of 99.31%. At the same time, nitrate in wastewater is also converted into ammonium ions for resource utilization, with a DNRA efficiency of 59.51%, which is about 15% higher than the DNRA efficiency in published studies.

[0024] (3) This invention utilizes pollutants in wastewater in situ as carbon and nitrogen sources to achieve effective wastewater treatment, energy recovery, and sustainable utilization of nitrate nitrogen.

[0025] (4) The bioelectrochemical system utilized in this invention has the characteristics of low energy consumption, low cost and strong environmental adaptability. The biofilm contains a large number of SMX degrading bacteria and DNRA bacteria and can exist stably, which can stably achieve efficient removal of SMX and removal and conversion of nitrate, providing the possibility for nitrogen resource recovery. Attached Figure Description

[0026] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of a microbial electrochemical device proposed in this invention for removing sulfonamide compounds from wastewater and recovering nitrogen resources.

[0027] Explanation of reference numerals in the attached figures: 1. Anode inlet / outlet; 2. First three-way valve; 3. Power supply; 4. Second three-way valve; 5. Anode; 6. Microorganisms; 7. Cation exchange membrane; 8. Cathode; 9. Cathode inlet / outlet; 10. Tank body. Detailed Implementation

[0028] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0029] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0030] A bioelectrochemical device was constructed in wastewater. The microbial electrolysis cell includes an anode inlet / outlet (1), a first three-way valve (2), a power supply (3), a second three-way valve (4), an anode (5), microorganisms (6), a cation exchange membrane (7), a cathode (8), a cathode inlet / outlet (9), and a cell body (10), as detailed below. Figure 1 As shown in the diagram, the system is maintained at a constant potential of -0.4V to 0V. The tank is separated by a cation exchange membrane 5, forming an anode chamber and a cathode chamber. The anode chamber is filled with wastewater containing sulfonamide compounds and nitrates to be treated. Under anoxic or microaerobic conditions, microorganisms use organic matter such as sulfonamide compounds as carbon sources and electron donors, and nitrates as electron acceptors in the metabolic process. The generated electrons are transferred to the cathode by an applied voltage. Under the influence of the concentration difference between the anode and cathode, the resulting ammonium ions pass through the cation exchange membrane and enter the cathode. The cathode chamber is filled with cathodic solution (including NaCl solution, phosphate buffer solution, etc.), and pH control is achieved through a spontaneous alkali production process, thereby realizing the ammonia recovery process.

[0031] This invention also provides an enhanced method for the removal of sulfonamides and nitrate conversion based on a microbial electrochemical system. The specific implementation process includes the following steps: (1) Start-up stage: Construct an anaerobic serum bottle system and investigate the effects of different co-metabolite substrates (glucose, acetate, and lactate) on the removal performance of sulfonamides and nitrogen conversion pathways. (2) Operation stage: Construct a microbial electrochemical system with weak electrical intervention, select lactate as the optimal co-metabolite substrate based on experimental results, and investigate the effects of the SMX single metabolism system and the co-metabolite system with lactate introduction on the SMX degradation performance and DNRA efficiency.

[0032] Example 1 Both the anode and cathode of the microbial electrolysis cell are made of self-made graphite felt, and the cation exchange membrane is a CMI-7000, with a constant potential of -0.2V applied. A sequencing batch reactor (SBR) operation mode is used to treat wastewater containing SMX and nitrates, with a single operating cycle set at 7 days. The effective working volume of both the anode and cathode chambers is 80 mL. At the end of each cycle, the anode chamber has an 80% water exchange ratio, retaining 15 mL of the mixed solution (containing activated sludge and microbial metabolites) as the inoculum for the next cycle to maintain microbial community activity; the cathode chamber is completely replaced, and a 50 mM sodium chloride solution is re-injected to ensure the ion conduction efficiency and pH stability of the cathode reaction system. The preparation process of graphite felt is as follows: Four graphite felts were bundled together with cable ties and fixed to a platinum electrode clamp (model 7110, parameter 10x15mm platinum sheet conductivity, purchased from Tianjin Hongqiao District Tianmei Instrument Store) using titanium wire (0.8mm diameter) to form the anode and cathode. The graphite felts were 2cm long, 0.5cm wide, and 6cm high.

[0033] First, the graphite felt is rinsed with deionized water to remove impurities from its surface. Then, it is rinsed with a 1 mol / L dilute hydrochloric acid solution to remove impurities and oxidized substances from its surface, thereby improving its purity and surface activity. Finally, it is rinsed again with deionized water and dried in an oven to serve as the anode and cathode.

[0034] The cation exchange membrane is treated as follows: The cation exchange membrane was soaked in a saturated sodium chloride solution for 24 hours to convert the membrane to the sodium form, remove impurities from the membrane surface and interior, and promote the swelling and stabilization of the membrane structure. Then it was soaked in deionized water for 24 hours to remove residual salt, balance the osmotic pressure inside and outside the membrane, and activate the ion conduction channels. Finally, it was air-dried and trimmed into a suitable shape for use in the reactor.

[0035] The activation process of the microbial electrolysis cell is as follows: The prepared anode and cathode were placed in the battery for activation. 10 ml of anolyte (consisting of effluent from a serum bottle acclimated for 2 months and activated sludge), 3.50 ml of LMX solution (1020 mg / L), and 3.75 ml of nitrate solution (2885 mg / L) (separate metabolic system) were added to the reactor. Alternatively, use 2.00 mL of SMX solution, 0.75 mL of sodium lactate solution (1280 mg / L), and 3.75 mL of nitrate solution (co-metabolism system).

[0036] Alternatively, 2.00 mL SMX solution, 0.75 mL glucose solution (1280 mg / L), and 3.75 mL nitrate solution (co-metabolism system). Alternatively, use 2.00 mL SMX solution, 0.75 mL acetate solution (1280 mg / L), and 3.75 mL nitrate solution (co-metabolism system). Then, the volume was adjusted to 80 mL with synthetic wastewater containing trace elements. High-purity nitrogen gas (99.99%) was introduced into the solution for 5 minutes to remove dissolved oxygen and create an environment suitable for anaerobic metabolism of microorganisms. A 50 mM sodium chloride solution was added to the cathode chamber, and the dynamic changes in the anolyte current density were observed. Once the current stabilized, the electrodialysis tank was considered to have been successfully started up initially.

[0037] The formula for the artificially synthesized wastewater is as follows: The concentrations are: KCl 130 mg / L, NaH₂PO₄ 2450 mg / L, and Na₂HPO₄ 4580 mg / L. (These ratios are not unique and can be adjusted as needed; this is just an example.) The components and contents of the trace element solution are as follows: 1.50 g / L FeCl3∙6H2O, 0.03 g / L CuSO4∙5H2O, 0.12 g / L MnCl2∙4H2O, 0.06 g / L NaMoO4∙H2O, 0.12 g / L ZnSO4∙H2O, 0.15 g / L CoCl2∙6H2O, 0.18 g / L KI, 0.15 g / L H3BO3, 12.74 g / L LEDTA-Na2∙2H2O (the proportions are not unique and can be adjusted as needed; this is just an example).

[0038] Subsequently, a stepwise C / N control strategy was adopted for the anode chamber, as follows: the influent nitrate concentration was fixed at 15 mg / L, and SMX or lactate, glucose, and acetate were added initially. The COD concentration of the influent was controlled at 75±5 mg / L (corresponding to C / N=5). COD was determined by the potassium dichromate method, and nitric acid was determined by ultraviolet spectrophotometry.

[0039] In the serum bottle system, the lactate co-metabolism reactor achieved a SMX degradation rate of 65.76% and a nitrate conversion rate of 84.42% during the steady-state phase. This is approximately 1.8 times the SMX degradation rate and nitrate conversion rate of glucose (35.94%, 45.72%) and acetate (38.16%, 52.53%) under the same conditions.

[0040] Salt was used to verify the initial C / N ratio. After three cycles of stable operation under these conditions (with a stability standard of ≤5% fluctuation in system electrochemical parameters and effluent performance), the COD concentration was gradually increased to 105±5 mg / L (C / N=7) and 135±5 mg / L (C / N=9) by increasing the carbon source dosage. The "3 acclimatization cycles + stability verification" step was repeated for each C / N stage, and the system performance under different C / N ratios was finally evaluated.

[0041] Example 2 An electrolytic cell containing 2.00 mL of SMX solution, 0.75 mL of glucose solution (1280 mg / L), and 3.75 mL of nitrate solution (co-metabolism system) obtained in Example 1 was used. SMX, lactate, nitrate, anolyte, and synthetic wastewater were introduced into the anode chamber. Specific parameters were as follows: the total reaction volume was 80 mL, including 2.50 mL of 1020 mg / L SMX solution, 1.25 mL of 1280 mg / L sodium lactate solution, 4.20 mL of 2885 mg / L nitrate solution, and 10 mL of anolyte. The volume was then adjusted to the final volume with synthetic wastewater. The final influent water quality parameters were COD 105 ± 10 mg / L and NO3- 20 mg / L. - -N 15±2 mg / L (C / N=7). The mass ratio of SMX, lactate, nitrate to synthetic wastewater was 1 : 0.63 : 4.75 : 24333. Other operating parameters were as described in Example 1.

[0042] After the system starts up, sulfamethoxazole and lactate are utilized by microorganisms to generate electrons. These electrons move to the anode and are transferred to the cathode via an applied voltage to generate an electric current. Nitrate, as an electron acceptor, participates in the metabolic process and is converted into ammonium ions (NH4+). + Under the influence of the concentration difference between the cathode and anode, NH4 + It passes through the cation exchange membrane and enters the cathode.

[0043] On days 0, 1, 3, 5, and 7, the concentrations of COD, SMX, nitrate nitrogen, nitrite nitrogen, and ammonia nitrogen in the anolyte and the ammonia nitrogen concentration in the cathode effluent were measured during the stable phase. On day 0 of the co-metabolism system, the effluent COD concentration at the anode was 102 mg / L, SMX concentration was 28.76 mg / L, nitrate nitrogen concentration was 16.12 mg / L, nitrite nitrogen concentration was 0.24 mg / L, anode ammonia nitrogen concentration was 0.39 mg / L, and cathode ammonia nitrogen concentration was 0.00 mg / L. On day 1, the effluent COD concentration at the anode was 96 mg / L, SMX concentration was 28.30 mg / L, nitrate nitrogen concentration was 10.60 mg / L, nitrite nitrogen concentration was 0.05 mg / L, anode ammonia nitrogen concentration was 1.07 mg / L, and cathode ammonia nitrogen concentration was 0.81 mg / L. On day 3, the effluent COD concentration at the anode was 80 mg / L, SMX concentration was 25.24 mg / L, nitrate nitrogen concentration was 6.60 mg / L, and nitrite nitrogen concentration was 0.21 mg / L. The ammonia nitrogen concentration was 1.61 mg / L, and the cathode ammonia nitrogen concentration was 1.85 mg / L. On day 5, the anode effluent COD concentration was 52 mg / L, SMX concentration was 14.29 mg / L, nitrate nitrogen concentration was 4.22 mg / L, nitrite nitrogen concentration was 0.33 mg / L, anode ammonia nitrogen concentration was 1.61 mg / L, and cathode ammonia nitrogen concentration was 1.96 mg / L. On day 7, the anode effluent COD concentration was 14 mg / L, with a removal rate of 86.27%; SMX concentration was 5.92 mg / L, with a removal rate of 83.03%; nitrate nitrogen concentration was 2.42 mg / L, with a removal rate of 84.89%; nitrite nitrogen concentration was 0.26 mg / L; anode ammonia nitrogen concentration was 1.79 mg / L, and cathode ammonia nitrogen concentration was 2.59 mg / L. The DNRA efficiency was 59.51%. DNRA efficiency is the difference between the total ammonia nitrogen in the effluent from the anode and cathode on day 7 and the total ammonia nitrogen in the effluent from the anode and cathode on day 0, and the nitrogen content consumed over seven days.

[0044] Comparative Example 1 SMX removal and nitrate conversion were carried out according to the method in Example 2, with the only difference being that the carbon source was only SMX; SMX, nitrate, anolyte, and synthetic wastewater were added and introduced into the anode chamber. Sodium lactate solution was not added, and the remaining conditions were completely the same as in Example 2.

[0045] After running for 7 days, the concentrations of COD, SMX, nitrate nitrogen, nitrite nitrogen, and ammonia nitrogen in the anode effluent and the ammonia nitrogen concentration in the cathode effluent were tested. On day 0 of the single metabolic system, the anode effluent COD concentration was 108 mg / L, SMX concentration was 53.12 mg / L, nitrate nitrogen concentration was 15.73 mg / L, nitrite nitrogen concentration was 0.06 mg / L, anode ammonia nitrogen concentration was 0.206 mg / L, and cathode ammonia nitrogen concentration was 0.00 mg / L. On day 7, the COD concentration in the effluent from the anode was 45 mg / L, with a removal rate of 59.09%; the SMX concentration was 21.15 mg / L, with a removal rate of 61.17%; the nitrate nitrogen concentration was 5.42 mg / L, with a removal rate of 65.55%; the nitrite nitrogen concentration was 0.04 mg / L; the anode ammonia nitrogen concentration was 1.31 mg / L; the cathode ammonia nitrogen concentration was 1.68 mg / L; and the DNRA efficiency was 34.55%. The DNRA efficiency is the difference between the total ammonia nitrogen in the effluent from the anode and cathode on day 7 and the total ammonia nitrogen in the effluent from the anode and cathode on day 0, divided by the nitrogen content consumed over seven days.

[0046] Comparative Example 2 SMX removal and nitrate conversion were performed according to the method in Example 2, with the only difference being the open-circuit condition. The open-circuit condition was used; all other conditions were completely the same as in Example 2.

[0047] After operating for 7 days, the concentrations of COD, SMX, nitrate nitrogen, nitrite nitrogen, and ammonia nitrogen in the effluent were tested. On day 0, the open-loop co-metabolism system produced effluent COD of 103 mg / L, SMX of 27.98 mg / L, nitrate nitrogen of 17.15 mg / L, nitrite nitrogen of 0.26 mg / L, and ammonia nitrogen of 0.08 mg / L. On day 7, the effluent COD was 49 mg / L (removal rate 53.3%), SMX was 11.28 mg / L (removal rate 55.11%), nitrate nitrogen was 7.31 mg / L (removal rate 55.83%), and ammonia nitrogen was 0.69 mg / L, with a DNRA efficiency of 13.87%. DNRA efficiency is the difference between the total ammonia nitrogen in the effluent on day 7 and day 0, divided by the nitrogen content consumed over seven days.

[0048] Comparative Example 3 SMX removal was performed using the method described in Comparative Example 2, with the only difference being that the carbon source was SMX only, without the addition of nitrates and lactates.

[0049] SMX, anolyte, and synthetic wastewater were added and introduced into the anode chamber; the remaining conditions were completely the same as in Example 2.

[0050] After running for 7 days, the effluent COD, SMX, and ammonia nitrogen concentrations were tested. On day 0, the effluent COD concentration was 106 mg / L, SMX concentration was 50.12 mg / L, and ammonia nitrogen concentration was 0.00 mg / L. On day 7, the effluent COD concentration was 92 mg / L, with a removal rate of 13.21%; the SMX concentration was 44.19 mg / L, with a removal rate of 11.16%; the ammonia nitrogen concentration was 0.00 mg / L, and the DNRA efficiency was 0.

[0051] Table 1 shows a comparison of key parameters and processing performance in Examples 2, 1, 2 and 3.

[0052] Table 1: Metabolic substrate nitrates Circuit conditions SMX degradation rate Nitrate removal rate DNRA Example 2 Lactate, SMX have Closed-circuit 83.03% 84.89% 59.51% Comparative Example 1 SMX have Closed-circuit 61.17% 65.55% 34.55% Comparative Example 2 Lactate, SMX have open circuit 55.11% 55.83% 13.87% Comparative Example 3 SMX none open circuit 11.16% / 0 The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. 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 microbial electrochemical device for removing sulfonamide compounds from wastewater and recovering nitrogen resources, characterized in that: It includes a pool body, and within the pool body, an anode chamber and a cathode chamber are separated by a cation exchange membrane; An anode is provided in the anode chamber, and a cathode is provided in the cathode chamber; the anode and cathode are connected to a power source for applying a constant potential; The anode chamber treats wastewater containing sulfamethoxazole and nitrate under anoxic or microaerobic conditions. The cathode chamber is filled with a cathodic solution containing NaCl and phosphate buffer, enabling spontaneous alkali production and ammonia recovery.

2. The microbial electrochemical device for removing sulfonamide compounds from wastewater and recovering nitrogen resources according to claim 1, characterized in that: The power supply applies a constant potential to the system from -0.4V to 0V; Microorganisms capable of degrading sulfonamide compounds are attached to the anode.

3. The microbial electrochemical device for removing sulfonamide compounds from wastewater and recovering nitrogen resources according to claim 1, characterized in that: Both the anode and cathode are carbon-based material electrodes, which are selected from graphite felt, carbon brush, or graphite rod.

4. The microbial electrochemical device for removing sulfonamide compounds from wastewater and recovering nitrogen resources according to claim 1, characterized in that: The anode chamber is connected to an anode inlet / outlet pipe, which is connected to a first three-way valve. The cathode chamber is connected to a cathode inlet / outlet pipe, which is connected to a second three-way valve.

5. A method for removing sulfonamide compounds from wastewater and recovering nitrogen resources, comprising using a microbial electrochemical device for removing sulfonamide compounds from wastewater and recovering nitrogen resources as described in any one of claims 1-4, characterized in that: Includes the following steps: S1: Add co-metabolite carbon source, nitrate, sulfonamide compounds and wastewater to the anode chamber, and introduce nitrogen gas to remove dissolved oxygen into the anode chamber. Add catholyte to the cathode chamber and apply a constant potential to start the system. Subsequently, fix the influent nitrate concentration and operate in a sequential batch mode. Increase the carbon-nitrogen ratio by gradually increasing the amount of co-metabolite carbon source added. Operate under each carbon-nitrogen ratio condition until the system performance is stable and the microbial acclimatization is completed. S2: During the stable operation phase after domestication, the microorganisms in the anode chamber degrade sulfonamide compounds and convert organic nitrogen into inorganic ammonia nitrogen, while reducing nitrate to produce ammonium ions; the generated ammonium ions migrate to the cathode chamber and are converted into ammonia, and nitrogen is recovered by replacing the catholyte.

6. The method for removing sulfonamide compounds and recovering nitrogen from wastewater according to claim 5, characterized in that: The sulfonamide compounds in step S1 include one or more of sulfadiazine, sulfamethoxazole, sulfadiazine, sulfathiazole, sulfamididine, sulfamethoxypyrimidine, and sulfachlorpyridazine; The co-metabolic carbon source in step S1 includes one or more of glucose, acetate, and lactate.

7. The method for removing sulfonamide compounds and recovering nitrogen from wastewater according to claim 5, characterized in that: In step S1, the dosage of sulfonamide compounds, nitrate nitrogen, and co-metabolic carbon source in the anode chamber meets the requirements for influent chemical oxygen demand (COD) and nitrate nitrogen (NO3). - The mass ratio of -N is controlled between 5 and 9.

8. The microbial electrochemical method for removing sulfonamide compounds and recovering nitrogen resources from wastewater according to claim 5, characterized in that: The carbon-nitrogen ratio regulation in step S1 adopts a step-by-step increase strategy, sequentially increasing the COD / NO3 ratio. - The -N ratio was controlled at 5, 7, and 9 for acclimatization, and each stage was operated stably for at least 3 cycles.

9. The microbial electrochemical method for removing sulfonamide compounds and recovering nitrogen resources from wastewater according to claim 5, characterized in that: The sequential batch operation in step S1 is carried out in a cycle of 5-10 days. At the end of the cycle, 70%-90% of the liquid in the anode chamber is replaced, and 10%-30% of the mixed liquid is retained as the inoculum. The cathode chamber is completely replaced.

10. The microbial electrochemical method for removing sulfonamide compounds and recovering nitrogen resources from wastewater according to claim 4, characterized in that: Step S1 also includes pretreatment of the anode and cathode before system startup. The pretreatment method includes activating them by soaking in dilute hydrochloric acid solution and then rinsing them clean with deionized water. Step S1 also includes pretreatment of the cation exchange membrane before system startup. The pretreatment method includes soaking it in a saturated sodium chloride solution for 20-28 hours and then soaking it in deionized water for 20-28 hours.

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