A method for improving rapid sludge granulation and estrogen removal based on a dual-algae system

Abstract

This invention discloses a method for improving the rapid granulation of sludge and removing estrogen based on a dual-algae / bacterial system, belonging to the field of water pollution technology. The method includes establishing a dual-algae / bacterial system; modifying the electrodes of the cathode / anode chambers in the dual-algae / bacterial system, with the cathode being a carbon cloth material modified with a MoS2 photosensitive layer and the anode being a carbon felt material modified with Fe3O4 using magnetic response directional assembly; and periodically irradiating the cathode / anode chambers to improve the granulation speed of activated sludge and the removal rate of estrogen in wastewater. This invention enables the cultivation of oxygen-producing green algae in the cathode chamber and the enrichment of microalgae / activated sludge in the anode chamber to form a photosensitive microbial fuel cell. Simultaneously, the oxygen-producing green algae culture liquid in the cathode chamber is added to the anode chamber, achieving symbiotic coupling of bacteria and algae in the anode chamber to form algae-bacterial granular sludge. This dual-algae / bacterial system, under microcurrent and light irradiation, can promote sludge granulation and significantly shorten the granulation time, while also creating a microenvironment that accelerates the degradation of estrogen in wastewater.

Description

Technical Field

[0001] This invention relates to the field of water pollution treatment technology, specifically to a wastewater treatment method based on a dual-algae system to improve the rapid granulation speed of sludge and the estrogen removal rate. Background Technology

[0002] New pollutants (such as endocrine disruptors, perfluorinated compounds, microplastics, and antibiotics) have become a significant issue in national ecological and environmental governance due to their complex structures, recalcitrant nature, and high toxicity, carcinogenicity, and mutagenicity. Among them, endocrine disruptors (e.g., 17α-ethinyl estradiol, EE2) cause biological effects on individuals or communities by interfering with the endocrine function of microorganisms. Current water pollution control faces a dual challenge: while advanced oxidation technologies can rapidly degrade pollutants, they cannot control or reduce the toxic effects of intermediate products, posing secondary risks; activated sludge processes, as the mainstream biological treatment technology, only achieve a removal rate of 60-80% for new pollutants (taking the typical estrogen EE2 as an example). Their fundamental bottleneck lies in the loose structure of sludge flocs, their susceptibility to loss, and their weak resistance to shock loads, leading to microbial community instability and limited degradation efficiency.

[0003] To overcome the aforementioned limitations, current research has shifted towards activated sludge granulation technology. This involves inducing sludge self-assembly into a dense three-dimensional structure through artificial means (such as selective pressure regulation and hydrodynamics). Granular sludge possesses multiple advantages, including improved settling performance, increased biomass, and deeper pollutant removal. Furthermore, the microalgae-bacteria synergistic system demonstrates innovative potential. O2 released by microalgae photosynthesis drives bacterial respiration, thereby degrading pollutants. The CO2 produced by bacterial respiration provides a carbon source for microalgae, forming a closed-loop carbon-oxygen cycle. Coupled with bacteria to create algae-bacteria granular sludge, it can achieve deep pollutant removal, reduce energy consumption by approximately 40%, and reduce sludge production by 30%. Despite the significant advantages of algae-bacteria granular sludge, its engineering application is still constrained by the fatal flaw of an excessively long granulation cycle. Under natural conditions, the self-assembly of algae and bacteria takes more than 60 days, significantly extending the wastewater treatment cycle. This long cycle leads to a 40% reduction in reactor utilization and a 35% increase in operating costs, severely hindering the technology's widespread adoption. Therefore, developing a new method to accelerate the self-assembly of bacteria and algae and reduce the granulation cycle from more than 60 days to less than 30 days has become a key innovative path to break through the industrialization of bacterial and algae granular sludge technology. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a method for improving the rapid granulation of sludge and removing estrogen based on a dual-algae system.

[0005] A method for improving the rapid granulation and estrogen removal of sludge based on a dual-algae system includes the following steps:

[0006] A dual-algae system is established, comprising a cathode chamber and an anode chamber separated by gravel. The cathode chamber contains a cathode, and the anode chamber contains an anode. The cathode and anode are connected by titanium wires located outside the cathode and anode chambers, with resistance boxes mounted on the titanium wires. The cathode is made of carbon cloth, and the anode is made of carbon felt. The cathode chamber contains a microalgae solution that can produce oxygen through photosynthesis, and the anode chamber contains wastewater containing activated sludge to be granulated and estrogen, as well as the microalgae solution from the cathode chamber.

[0007] Water was introduced into the anode chamber of the dual-algae system, with a wastewater to microalgae solution volume ratio of 80–90:1. The cathode chamber was then illuminated for 8–16 hours at a light intensity of 80–260 μmol·s⁻¹. -1 ·m -2 During the illumination period, the anode chamber is aerated for 217–325 minutes, settled for 10–15 minutes, and drained for 2–3 minutes to complete the granulation of activated sludge to be granulated and the removal of estrogen from the wastewater.

[0008] Explanation: The above method utilizes the synergistic effect of microalgae and activated sludge under light and microcurrent stimulation to achieve efficient sludge granulation and simultaneous estrogen removal. The cathode chamber of the dual-algae system employs modified carbon material with a photosensitive layer attached to microalgae, which releases oxygen under light to ensure the smooth progress of the reduction reaction. The algae source in the anode chamber is pumped to the anode chamber via a peristaltic pump through a pipe above the cathode chamber, forming the microalgae-bacteria system. This device, under electrochemical action and with microalgae-bacteria granular sludge, not only accelerates estrogen removal but also shortens the granulation cycle of the microalgae-bacteria granular sludge. Compared to the traditional activated sludge method, it significantly shortens the granulation cycle and improves estrogen removal efficiency. More importantly, it avoids the toxic effects of estrogen intermediates on microorganisms in the environment, achieving the dual goals of sludge resource utilization and deep wastewater treatment. It boasts advantages of high efficiency, low carbon footprint, and sustainability.

[0009] Furthermore, the microalgae solution is an aqueous solution of green algae with an OD680 of 0.8 to 1, wherein the green algae is Chlorella vulgaris, and the MLSS of the activated sludge to be granulated in the wastewater in the anode chamber is 2 to 4 g / L.

[0010] Note: The MLSS of the activated sludge described above ensures a sufficient amount of microorganisms in the electrode material and also ensures the biomass for granulation of granular sludge. By clearly defining the green algae solution and its concentration, a reproducible operating standard is provided for the experiment or process, avoiding deviations in implementation results due to concentration fluctuations or mixed algae species. Chlorella releases oxygen through photosynthesis, increasing the activity of aerobic activated sludge and promoting the cooperation between bacteria and algae. Chlorella secretes algal organic matter under light, accelerating the contact of activated sludge and effectively improving the granulation time of bacterial-algae granular sludge.

[0011] Furthermore, the carbon cloth material is a carbon cloth modified with molybdenum disulfide; the carbon felt material is made of Fe3O4 magnetic particles loaded with a Fe3O4 magnetic particle loading of 5.79 mg / cm³. 2 (The carbon felt is 0.5cm thick); the anode chamber is equipped with an aeration device and a magnetic coil.

[0012] Explanation: Fe3O4 magnetic particles can be oriented and assembled through magnetic response. Magnetic response oriented assembly refers to the precise control of the arrangement, aggregation morphology, and surface properties of Fe3O4 magnetic particles in carbon felt through an external magnetic field. This oriented assembly enables customized adjustments to the microstructure and macroscopic properties of carbon felt, achieving purposes such as accelerated electron transfer and directional transport.

[0013] Furthermore, the method for modifying the carbon cloth includes:

[0014] At a temperature of 25℃, add 0.2-0.6g of sodium molybdate, 1-2g of thioacetamide and 0.2-0.4g of L-cysteine ​​to 70-90mL of ultrapure water, and stir magnetically for 30min at a stirring speed of 200-300rpm to obtain the reaction solution.

[0015] To obtain MoS2 photosensitive material, 1M hydrochloric acid was added to the reaction solution to adjust the pH to 3.9–4.1. The reaction solution was then transferred to a 100 mL polytetrafluoroethylene liner for hydrothermal reaction at 180–220 °C for 24 h to obtain an intermediate product. The intermediate product was centrifuged at 5000 rpm for 8–10 min, and the supernatant was collected. This supernatant was then centrifuged at 15000 rpm for 8–10 min to obtain particulate matter. This particulate matter was ultrasonicated in isopropanol for 30 min, then centrifuged at 15000 rpm for 8–10 min and vacuum dried at 120 °C for 1–2 h to obtain the MoS2 photosensitive material.

[0016] The carbon cloth was pretreated by ultrasonically cleaning it sequentially with acetone, ethanol, and ultrapure water for 30-40 minutes each. Then, the carbon cloth was immersed in a 3:1 mixture of H2SO4 and HNO3 for 30 minutes. After that, the carbon cloth was washed with ultrapure water until neutral. Finally, the carbon cloth was immersed in a 2% (w / w) aqueous solution of 3-aminopropyltriethoxysilane at 60°C for 4 hours to obtain the pretreated carbon cloth.

[0017] Mixed modification: The pretreated carbon cloth was placed in an isopropanol solution containing 2 mg / mL MoS2 photosensitive material and centrifuged at 500 rpm for 1-2 min, and then centrifuged at 3000 rpm for 2-3 min to complete the preloading, thus obtaining the preloaded carbon cloth. It was then vacuum dried at 120℃ for 0.5-1.5 h to obtain the carbon cloth material.

[0018] The modification method of the carbon felt includes:

[0019] The carbon felt was pretreated by ultrasonically cleaning it with acetone, ethanol and ultrapure water for 30-40 minutes each, then immersing it in a mixture of H2SO4 and HNO3 (volume ratio 3:1) for 30 minutes. The carbon felt was then cleaned with ultrapure water until neutral and dried at 60°C for 12 hours to obtain the pretreated carbon felt.

[0020] Mixed modification: The pretreated carbon felt was placed in a treatment solution, which was obtained by mixing 100 mL of ultrapure water, 2.70 g of FeCl3·6H2O and 0.99 g of FeCl2·4H2O; N2 was introduced into the treatment solution and magnetic stirring was performed at a speed of 500 rpm; 15 mL of ammonia water was added dropwise to the treatment solution at a drop rate of 1 mL / min; the treatment solution was then reacted at a temperature of 80 °C for 1 h and vacuum dried at a temperature of 60 °C for 12 h to obtain the carbon felt material.

[0021] Explanation: The modified carbon cloth material used for the photosensitive layer of the cathode improves the efficiency of the oxygen reduction reaction and the cathode's electron-accepting ability, while also increasing the photosensitization capability of the carbon cloth photosensitive coating. Simultaneously, the anode chamber utilizes a magnetically responsive, directionally assembled modified carbon felt material containing activated sludge, which works synergistically with aeration. This magnetically responsive, directionally assembled modified carbon felt material aims to accelerate the adhesion of microorganisms and, secondly, to acclimate electrobacteria under the action of the magnetic coil, facilitate the transfer of extracellular electrons or electron mediators to the anode surface for enrichment. The aeration process aims to accelerate the adhesion of activated sludge to the electrode material and, secondly, to accelerate the granulation of bacterial and algal granular sludge under oxygen dynamics and microcurrent conditions.

[0022] Furthermore, the aeration rate is 2 L / min;

[0023] Note: The above aeration range can maintain a suitable dissolved oxygen concentration in the anode chamber, ensuring the metabolic activity of aerobic microorganisms and the sludge granulation effect.

[0024] Furthermore, when the cathode chamber is intermittently illuminated, the current between the cathode and the anode can be controlled to be 2–8 A / m by the resistance of the resistance box. 3 .

[0025] Furthermore, the temperature of both the cathode chamber and the anode chamber is 20–25°C.

[0026] Furthermore, the method for establishing the dual-algae system includes:

[0027] S1. Assemble the cathode chamber and anode chamber, fill the connection between the cathode chamber and anode chamber with gravel for physical separation, and connect the cathode chamber and anode chamber through a connecting pipe with a peristaltic pump.

[0028] S2. Carbon cloth material is used as the cathode and carbon felt material is used as the anode. The cathode is added to the cathode chamber and the anode is added to the anode chamber. A resistance box with adjustable resistance and titanium wire are used to connect the cathode and the anode.

[0029] S3. Microalgae solution is loaded into the cathode chamber, and wastewater containing activated sludge to be granulated and estrogen is loaded into the anode chamber. A lamp tube for illumination is installed in the cathode chamber, and an aeration device and magnetic coil are installed in the anode chamber. The illumination in the cathode chamber can generate oxygen, and the microalgae solution and activated sludge in the anode chamber form bacterial-algae granular sludge under the action of aeration. The dual-algae-bacterial system is established.

[0030] Explanation: In the above method, the microalgae liquid discharged from the cathode enters the anode chamber and, under aeration, forms granular sludge of bacteria and algae. Simultaneously, the microalgae cathode and the activated sludge anode constitute a microbial fuel cell of bacteria and algae, thus completing the establishment of the dual-bacterial-algae system. The above method ensures that the system achieves cooperation between microalgae and activated sludge in a certain space, shortens the granulation time of granular sludge of bacteria and algae, and ensures the efficient removal of pollutants such as estrogen, providing a reproducible construction method for the dual-bacterial-algae system.

[0031] The beneficial effects of this invention are:

[0032] (1) This invention proposes a dual-bacterial-algae system for the first time. This system is formed by combining a microalgae-algae microbial fuel cell system (using microalgae as the cathode and activated sludge as the anode) with a subsequently formed microalgae-algae granular sludge system. The cathode material uses modified carbon cloth with a photosensitive layer attached to microalgae, while the anode material uses modified carbon felt material with magnetic response orientation assembly of activated sludge. This avoids the drawback of insufficient cathode oxygen concentration in traditional microbial fuel cells and improves the current density of the fuel cell under modified anode and cathode conditions. Most importantly, the synergistic effect of the dual-bacterial-algae system shortens the sludge granulation cycle and improves estrogen removal efficiency.

[0033] (2) The cathode / anode chambers respectively use modified carbon cloth material with photosensitive layer and modified carbon felt material with magnetic response orientation assembly as electrode materials. The advantage is that the light increases the photosynthesis of microalgae, enhances the oxygen reduction reaction of the cathode, increases the current density of the modified fuel cell, accelerates the production of extracellular polymers of activated sludge and bacterial and algal granular sludge, and further increases the removal efficiency of estrogen; the magnetic field promotes the uniform distribution and rapid aggregation of microorganisms on the carbon felt surface, and further accelerates the formation of sludge particles.

[0034] (3) Compared with the traditional activated sludge process, the dual-bacterial algae system significantly shortens the granulation cycle and improves the efficiency of reducing the toxicity of estrogen and intermediate products, avoiding secondary harm to aquatic organisms. It achieves the dual goals of sludge granulation and deep sewage treatment, and has the advantages of high efficiency, low carbon and sustainability, making up for the shortcomings of the current deep purification process for recalcitrant organic pollutants.

[0035] (4) By providing a relatively stable microenvironment for microorganisms, the dual-bacterial algae system can effectively resist adverse environmental factors and enable microorganisms to maintain high degradation activity under a wider range of environmental conditions.

[0036] (5) The method provided by the present invention can be adjusted according to the characteristics and treatment requirements of different wastewaters, and has high flexibility and controllability, and is applicable to a variety of different types of wastewater treatment. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the equipment for the dual-algae system in an embodiment of the present invention;

[0038] Figure 2 These are scanning electron microscope (SEM) images comparing the cathode and anode materials before and after in an embodiment of the present invention.

[0039] Figure 3 These are scanning electron microscope images of Chlorella and activated sludge attached to the anion / anode materials in the embodiments of the present invention;

[0040] Figure 4 This is a schematic diagram and a scanning electron microscope image of the successfully cultured bacterial and algal granular sludge in the anode chamber in an embodiment of the present invention.

[0041] Figure 5 This is a graph showing the current density and power density of the dual-bacteria algae system in Example 1 of the present invention;

[0042] Figure 6 These are the current density and power density diagrams of the dual-bacterial algae system in Embodiment 1 and Comparative Example 9 of the present invention. Detailed Implementation

[0043] As described in the background, the purpose of converting activated sludge into granular sludge is to improve its performance in various aspects, thereby addressing recalcitrant pollutants in traditional activated sludge processes and reducing other environmental problems. However, current technologies have long activated sludge granulation cycles. Current methods use SBR (Sequencing Batch Reactor) to achieve granulation through continuous aeration; however, the SBR granulation process is subject to many unknown factors, such as a lack of algal sources and severe sludge loss, leading to a prolonged granulation cycle, typically exceeding 60 days or even longer. Therefore, shortening the activated sludge granulation cycle is crucial for wastewater treatment.

[0044] Furthermore, existing technologies have low removal rates for complex organic pollutants (such as estrogens) in wastewater. Taking 17α-ethynylestradiol (EE2), a typical estrogen, as an example, although its environmental concentration is in the ng / L range, it has a strong endocrine-disrupting effect, and existing biological treatment systems generally achieve removal rates below 70%. This is because conventional wastewater treatment suffers from insufficient hydrodynamics leading to low dissolved oxygen, activated sludge loss resulting in decreased biomass, and complex environmental conditions leading to weak microbial activity, resulting in low concentrations of pollutants in the effluent. While conventional electrochemical methods can degrade recalcitrant pollutants to some extent, it remains unknown whether they promote activated sludge granulation and simultaneously achieve deep removal of EE2.

[0045] To address these limitations, a microbial fuel cell is employed. Algae photosynthesis sustainably supplies dissolved oxygen to the cathode, resolving the oxygen limitation issue in the cathode chamber of the microbial fuel cell. Microcurrent stimulation activates extracellular electron transport (EET) in functional microorganisms, promoting the accumulation of electrochemical bacteria and stimulating the secretion of extracellular polymeric substances (EPS), thereby accelerating sludge granulation.

[0046] In this embodiment of the invention, a three-in-one design of physical zoning, material cycling, and electrochemical regulation is adopted to achieve synergistic enhancement of activated sludge granulation acceleration and estrogen degradation, which can provide a scientific and engineering feasible solution for the upgrading and transformation of sewage treatment plants; the specific implementation method is as follows;

[0047] Example 1: A method for improving the rapid granulation and estrogen removal of sludge based on a dual-algae system, comprising the following steps:

[0048] Establish a dual-algae / bacterial system; such as Figure 1 As shown, the above-mentioned dual-algae system includes a cathode chamber and an anode chamber, which are separated by gravel. The cathode chamber is equipped with a cathode, and the anode chamber is equipped with an anode. The cathode and anode are connected by a titanium wire located outside the cathode chamber and the anode chamber. A resistance box is installed on the titanium wire. The cathode is made of carbon cloth material, and the anode is made of carbon felt material. The cathode chamber is filled with microalgae liquid that can produce oxygen through photosynthesis. The anode chamber is used to fill wastewater containing activated sludge to be granulated and estrogen, as well as microalgae liquid from the cathode chamber.

[0049] The cathode is made of carbon cloth material modified with MoS2 photosensitive material for microalgae attachment layer, and the anode material is made of carbon felt material modified with Fe3O4 and magnetically oriented assembly containing activated sludge. The cathode chamber is filled with microalgae liquid that can produce oxygen through photosynthesis, and the anode chamber is filled with wastewater containing activated sludge to be granulated and estrogen, as well as microalgae liquid from the cathode chamber. The outside is covered with a magnetic coil.

[0050] The methods for establishing a dual-algae system mentioned above include:

[0051] S1. Assemble the cathode chamber and anode chamber as described above, and fill the middle of the connection between the cathode chamber and anode chamber with 10cm of gravel for physical separation (e.g., ...). Figure 1 (As shown) and a ball valve is provided at the bottom of the cathode chamber, and the cathode chamber and anode chamber are connected by a connecting pipe with a peristaltic pump;

[0052] For example, such as Figure 1 The device shown has a cathode chamber with an outer tube inner diameter of 0.15m x 1m and an outer tube inner diameter of 0.06m x 1m. The anode chamber has an outer tube inner diameter of 0.15m x 1m. The anode chamber and the cathode chamber are roughly the same in shape, the difference being that the cathode chamber has an inner tube with an LED lamp that can change the light intensity. The anode chamber does not have an inner tube or LED lamp, but it is equipped with an aeration device, a magnetic coil, and a drain outlet. The aeration device and the magnetic coil are commercially available products using existing technology. The connection length between the cathode chamber and the anode chamber is 30cm, with gravel filling the middle 10cm.

[0053] S2. Carbon cloth material is used as the cathode, and carbon felt material is used as the anode. The cathode is added to the cathode chamber, and the anode is added to the anode chamber. Titanium wire and a resistance box are used to connect the cathode and anode. The carbon cloth material is modified with molybdenum disulfide. The carbon felt material is loaded with Fe3O4 magnetic particles that can be oriented and assembled through magnetic response. The loading amount of Fe3O4 magnetic particles is 5.79 mg / cm³. 2 (The carbon felt is 0.5cm thick);

[0054] For example, such as Figure 2 and Figure 3The images shown are scanning electron microscope (SEM) images of the cathode and anode materials, respectively; the carbon cloth and carbon felt have an area of ​​0.3 m × 0.06 m.

[0055] S2-1, The carbon cloth modification method is as follows: Add 0.5g of sodium molybdate, 1.2g of thioacetamide, and 0.3g of L-cysteine ​​to 80mL of ultrapure water. Stir magnetically for 30min at 250rpm at 25℃. Use 1M hydrochloric acid to adjust the pH to 4.0. Then transfer to a 100mL polytetrafluoroethylene liner for hydrothermal reaction at 200℃ for 24h to obtain an intermediate product. Centrifuge the intermediate product at 5000rpm for 9min, keep the supernatant, and centrifuge the supernatant again at 15000rpm for 9min. The particles were obtained, placed in isopropanol and sonicated for 30 min to remove agglomerates. They were then centrifuged at 15000 rpm for 9 min and vacuum dried at 120℃ for 1.5 h. The carbon cloth was pretreated by ultrasonically cleaning it sequentially with acetone, ethanol, and ultrapure water for 35 min each. The carbon cloth was then immersed in a 3:1 (v / v) mixture of H₂SO₄ and HNO₃ for 30 min. It was then washed with ultrapure water until neutral and further impregnated with 2% 3-aminopropyltriethoxysilane (APTES) at 60℃ for 4 h. Figure 2 (As shown in a); The pretreated carbon cloth was placed in a 2 mg / mL MoS2 / isopropanol solution. First, the carbon cloth was spread at a low speed of 500 rpm for 1 minute, then loaded at a high speed of 3000 rpm for 2.5 minutes. The loaded carbon cloth was then dried in a vacuum drying oven at 120℃ for 1 hour, primarily to enhance adhesion (e.g., as shown in a). Figure 2 (as shown in c).

[0056] S2-2, The carbon felt modification method is as follows: First, the carbon felt is pretreated by ultrasonically cleaning it with acetone, ethanol, and ultrapure water for 35 minutes each. Then, the carbon felt is immersed in a mixture of H2SO4 and HNO3 (volume ratio 3:1) for 30 minutes. The carbon felt is then cleaned with ultrapure water until neutral and placed in a drying oven at 60℃ for 12 hours (e.g., ...). Figure 2 (as shown in b); 2.70g FeCl3·6H2O, 0.99g FeCl2·4H2O, and 100mL ultrapure water were added to the pretreated carbon felt. N2 was then introduced and the mixture was magnetically stirred at 500rpm. 15mL of ammonia was added dropwise at a rate of 1mL / min. The reaction was carried out at 80℃ for 1h, followed by vacuum drying at 60℃ for 12h (as shown in b). Figure 2 (as shown in e).

[0057] S3. Add microalgae solution to the cathode chamber and wastewater containing activated sludge to be granulated and estrogen to the anode chamber. Install an LED lamp tube with adjustable light intensity in the cathode chamber. The dual-algae system is now established. The volume ratio of wastewater to microalgae solution in the anode chamber is 88.4 mL: 1 mL.

[0058] Specifically, the above-mentioned microalgae solution has an OD680 of 0.8 and is an aqueous solution of green algae; the green algae is Chlorella vulgaris, and the enrichment culture method of Chlorella vulgaris is as follows: Chlorella vulgaris is inoculated into BG11 medium and cultured at 25℃ and 2000 Lux for 11 days, and 13L of algal solution is taken into the cathode chamber in a clean bench.

[0059] The selected Chlorella had an absorbance of 0.8 at 680 nm; the LED tubes and magnetic coils were commercially available; the MLSS of the activated sludge to be granulated in the wastewater in the anode chamber was 3 g / L; the added wastewater was secondary influent from a wastewater treatment plant, with a COD concentration of 600 mg / L and ammonium nitrogen (NH4+). + The concentration of -N) was 60 mg / L, and the phosphate (PO4) concentration was... 3 The concentration of β-P was 6 mg / L, and the concentration of 17α-ethinyl estradiol (EE2) was 1 mg / L.

[0060] S4. Intermittently illuminate the cathode chamber of the dual-algae system, with each 12-hour interval being 12 hours of illumination followed by another 12-hour interval. During this illumination period, the anode chamber is operated periodically for 4 hours, including 10 minutes of water inflow, 210 minutes of aeration, 15 minutes of sedimentation, and 5 minutes of drainage. The drainage ratio during each cycle is 50%. During each water inflow cycle at the anode, 50 mL of algae solution is pumped from the cathode chamber to the anode chamber using a peristaltic pump. Simultaneously, the cathode chamber is filled with an equal volume of nutrient solution (BG11) for the microalgae. The anode is primarily supplied with estrogen-containing water. This cycle of water inflow, aeration, sedimentation, and drainage is repeated. The aeration rate is 2 L / min. After completing the above steps, the microbial fuel cell is started up, and its electrode materials are already adhered with Chlorella and activated sludge (such as...). Figure 3 (As shown), the granulation of activated sludge to be granulated and the removal of estrogen from the wastewater are then completed.

[0061] The temperature of both the cathode and anode chambers is 25℃, and the light intensity is 100 μmol·s⁻¹. -1 ·m -2 During intermittent illumination, the resistance between the cathode and anode materials is adjusted to 1000Ω; the diameter of the recovered algal granular sludge is preferably 2–4 mm, SVI 30 / SVI5 is preferably >0.8 (e.g., Figure 4 (As shown); the resistance box can control the current between the cathode and anode to be 2.0–8.0 A / m.3 ;

[0062] S5. The pretreatment of estrogen in the above wastewater was carried out by collecting it using an enrichment method, concentrating it using an HLB solid-phase extraction column, eluting the concentrated sample with ethyl acetate and methanol respectively, blowing it with nitrogen until the sample was moist, and then making up to volume with methanol in a chromatographic bottle. The concentration was detected using a liquid chromatograph. The estrogenic effect of EE2 was detected using yeast cells, and the luminescence intensity was detected using an enzyme-linked immunosorbent assay (ELISA) reader to obtain the estrogen effect value.

[0063] Comparative Example 1: Unlike Example 1, this example does not use a microbial fuel cell; instead, it employs a sequencing batch reactor (SBR) from the prior art. Specifically, activated sludge is first cultured in an SBR with a 4-hour cycle. Each cycle includes 45 minutes of influent, 10 minutes of settling, 180 minutes of aeration, and 5 minutes of effluent discharge. The aeration rate is set to 2 L / min. The height-to-diameter ratio of the SBR is 100:5. Influent, effluent, and aeration are all automatically controlled by a peristaltic pump, solenoid valve, and aeration pump connected to an automatic controller. The aeration device is located at the bottom of the SBR to provide sufficient oxygen. The resulting aerobic granular sludge is preferably co-cultured with algal solution in simulated wastewater to obtain microbial granules. The preferred volume ratio of microalgae in the aerobic granular sludge and algal solution is 1:1.5. The light intensity for co-culturing is 100 μmol·s⁻¹. -1 ·m -2 The preferred temperature for co-culturing is 25℃; the preferred light-dark time ratio for co-culturing is 1:1.

[0064] Comparative Example 2: The difference from Example 1 is that the cathode is made of unmodified carbon cloth, the anode is made of unmodified carbon felt, and no magnetic coil is installed.

[0065] I. To investigate the effects of different equipment systems on activated sludge granulation and estrogen removal;

[0066] The implementation results of Example 1 and Comparative Example 1 are compared as shown in Table 1 below:

[0067] Table 1. Cultivation time of bacterial and algal granular sludge and removal rate of EE2 and estrogen effect reduction efficiency under different modes

[0068] Particle culture time (days) 26 68 42 EE2 removal rate (%) 98.4 72.6 90.1 EE2 effect reduction rate (%) 99.1 75.9 86.9

[0069] In Table 1, regarding sludge granulation, the present invention, based on the dual-algae system, has significant advantages in the granulation of algae-bacterial granular sludge, requiring 26 days to complete granulation; while in Comparative Example 1, the granulation process required 68 days. The present invention shortens the time by 22 days, significantly outperforming the traditional scheme of Comparative Example 1. In terms of EE2 removal rate and toxicity reduction rate, the dual-algae system is superior to the conventionally cultured algae-bacterial granular sludge, with a removal rate increase of 25.8% and an effect reduction value of 23.2%.

[0070] Based on this, the power density generated by the dual-bacteria algae system can reach 1.8 W / m³. 3 This results in longer granulation time and greater EE2 removal and toxicity reduction compared to conventional culture methods (such as...). Figure 5 (As shown). Therefore, the dual-algae system in this embodiment of the invention promotes the occurrence of algal granulation and improves the efficiency of estrogen removal and toxicity reduction.

[0071] In Comparative Example 2, the unmodified anion / anode materials had shorter granulation time and lower estrogen removal efficiency than those in Example 1 of the present invention. Therefore, Example 1 is preferred.

[0072] Example 2: This example differs from Example 1 in that the ratio of wastewater to microalgae solution in the anode chamber is 80:1, and the carbon cloth area in S2 is 0.1m × 0.06m. During the illumination period, the anode chamber is subjected to 10 minutes of water intake, 210 minutes of aeration, 15 minutes of sedimentation, and 5 minutes of drainage to complete the granulation of activated sludge to be granulated and the removal of estrogen from the wastewater. The temperature of the cathode chamber is 25℃.

[0073] Example 3: This example differs from Example 1 in that the ratio of wastewater to microalgae solution in the anode chamber is 90:1, and the carbon felt area in S2 is 0.5m × 0.06m; during the illumination period, the anode chamber is subjected to 10min of water inlet, 210min of aeration, 15min of sedimentation, and 5min of drainage to complete the granulation of activated sludge to be granulated and the removal of estrogen from the wastewater; the cathode chamber temperature is 20℃.

[0074] Example 4: This example differs from Example 1 in that the light intensity is 80 μmol·s⁻¹. -1 ·m -2 .

[0075] Example 5: This example differs from Example 1 in that the light intensity is 260 μmol·s⁻¹. -1 ·m -2 .

[0076] Example 6: The difference between this example and Example 1 is that the intermittent lighting is every 8 hours for 8 hours.

[0077] Example 7: The difference between this example and Example 1 is that the intermittent illumination is every 16 hours, with 16 hours of illumination.

[0078] Example 8: The difference between this comparative example and Example 1 is that, during the aeration process, an additional lighting device was installed in the anode chamber for illumination, with a light intensity of 120 μmol·s⁻¹. -1 ·m -2 .

[0079] II. To investigate the effects of different operations on activated sludge granulation and estrogen removal using the equipment from Example 1; comparisons were made with Examples 1-8 and Comparative Examples 3-7, and the comparisons and results are as follows:

[0080] Comparative Example 3: This comparative example differs from Example 1 in that an equal amount of *Monoflagellates* was added to the anode chamber as in Example 1. The culture medium for the selected *Monoflagellates* was HB111, and the culture conditions were as follows: the temperature of the light incubator was set to 25±1℃, the light intensity was set to 2000 Lux, and the time was set to 12h day / 12h night.

[0081] Comparative Example 4: The difference between this comparative example and Example 1 is that the gravel filling the space between the cathode chamber and the anode chamber is replaced with a polystyrene sulfonate proton exchange membrane (PSSA-PEM).

[0082] Comparative Example 5: The difference between this comparative example and Example 1 is that the gravel filling the space between the cathode chamber and the anode chamber is replaced with a Gore-PEM proton exchange membrane.

[0083] Comparative Example 6: The difference between this comparative example and Example 1 is that the resistance box is adjusted to 50Ω.

[0084] Comparative Example 7: The difference between this comparative example and Example 1 is that the resistance box is adjusted to 5000Ω.

[0085] 1) Comparing Example 1 with Comparative Examples 3 to 7, the effects of different method settings on estrogen removal during activated sludge granulation time were verified. The results are shown in Table 2.

[0086] Table 2. Estrogen Removal Effect of Activated Sludge Granulation Time

[0087]

[0088]

[0089] As can be seen from Table 2, compared with Example 1 and Comparative Example 3, it can be seen that the addition of Chlorella in Example 1 can accelerate the granulation of activated sludge and achieve efficient removal of estrogen. Although the other algae added in Comparative Example 3 can have a certain effect, they cannot achieve rapid granulation and the effect of removing estrogen is not as good as that of Example 1 of the present invention. Therefore, Example 1 is more preferred.

[0090] Comparing Example 1, Comparative Example 4, and Comparative Example 5, it can be seen that Example 1, which uses gravel, has a better effect. This is because the porous structure of gravel promotes natural convection of water flow and enhances the mass transfer efficiency of substrate and product. The proton exchange membranes in Comparative Examples 4 and 5 have a lower effect than ordinary gravel because the diffusion of substrate and oxygen is hindered. Therefore, Example 1 is more preferred.

[0091] Comparing Example 1, Comparative Example 6, and Comparative Example 7, it can be seen that the current control in Example 1 has a better effect. This is because the microcurrent stimulates the metabolic rate of microorganisms, further promoting electron transfer efficiency. The granulation time and EE2 removal rate in Comparative Examples 6 and 7 are lower because when the external resistance is small, the current is too large, leading to excessive oxidation of microorganisms and further biofilm shedding / activity reduction. When the resistance is large, the current approaches zero, causing microorganisms to enter a "dormant" state, further reducing the substrate degradation rate. Therefore, Example 1 is more preferred.

[0092] 2) Examples 1 to 11 were compared to verify the effect of different parameter settings on estrogen removal during activated sludge granulation time. The results are shown in Table 3.

[0093] Table 3. Estrogen removal effect of activated sludge granulation time under different parameters.

[0094] Example 1 26 98.4 99.1 Example 2 34 95.6 91.8 Example 3 24 99.2 98.3 Example 4 32 93.6 90.2 Example 5 25 99.3 99.2 Example 6 32 92.8 91.1 Example 7 26 99.0 98.7 Example 8 24 99.7 98.1

[0095] As can be seen from Table 3, comparing Examples 1, 2, and 3, it can be found that the larger the area of ​​the cathode / anode material, the better the granulation time and EE2 removal rate. Compared with the components of Example 1, Example 3 is more preferred. Comparing Examples 1, 4, and 5, it can be found that the light intensity increases the algal solution concentration in the cathode chamber, resulting in a higher algal solution concentration drawn to the anode. Compared with Example 1, Example 5 is more preferred. Comparing Examples 1, 6, and 7, it can be found that the effects of Example 1 are similar, and the parameters of Examples 1 and 7 are more preferred. Comparing Examples 1 and 8, it can be found that adding extra light to the anode increases the granulation time in the anode chamber and improves the EE2 removal rate. Therefore, Example 8 is more preferred.

[0096] Example 9: Unlike Example 1, electroactive microorganism Shewanella (ATCCBAA-1097), sourced from a certain biotechnology company (www.beijingbio.tech), was added to the anode chamber at a dosage of 10... 9 CFU / mL.

[0097] The bacteria were cultured on LB medium, specifically consisting of 5.0 g yeast extract, 10.0 g peptone, 10.0 g NaCl, 1.5% agar, and 1000 mL distilled water at pH 7.0. The culture temperature was 30℃, and the culture time was 30 hours. The entire procedure must be performed in a sterile environment, strictly adhering to aseptic techniques to avoid contamination.

[0098] Example 10: The difference from Example 1 is that the amount of Pseudomonas aeruginosa (ATCC 9027) added to the anode chamber is the same as in Example 9;

[0099] The culture medium used consisted of: 5.0 g peptone, 3.0 g beef extract, 5.0 g NaCl, 15.0 g agar, 1.0 L distilled water, and a pH of 7.0. The culture temperature was 37°C, and the culture time was 30 hours. The entire procedure had to be performed in a sterile environment, strictly adhering to aseptic techniques to prevent contamination.

[0100] III. Investigating the effects of adding additional electrobacteria based on the equipment of Example 1 on activated sludge granulation and estrogen removal; a comparison was made with Example 1 above, and the comparison content and results are as follows:

[0101] Table 4. Estrogen removal effect of activated sludge granulation time under different parameters

[0102] Example 1 26 98.4 99.1 Example 9 23 100 99.5 Example 10 25 95.7 93.9

[0103] From Table 4 and Figure 6 As can be seen from the comparison of Examples 1, 9 and 10, it can be seen that the addition of Shewanella in Example 9 can accelerate activated sludge granulation and achieve deep removal of estrogen. The addition of Pseudomonas aeruginosa in Comparative Example 8 has less effect on promoting activated sludge granulation and removing EE2. The main reason is that Shewanella has excellent extracellular electron transfer ability, which directly transfers electrons to the electrode surface. Therefore, Example 9 is preferred.

[0104] Example 11: This example differs from Example 1 in that the modification method of the carbon cloth includes: adding 0.2g of sodium molybdate, 1g of thioacetamide, and 0.2g of L-cysteine ​​to 70mL of ultrapure water, and magnetically stirring for 30min to obtain a reaction solution; obtaining MoS2 photosensitive material; adding 1M hydrochloric acid to the reaction solution to adjust the pH to 3.9, and then transferring the reaction solution to a 100mL polytetrafluoroethylene liner for hydrothermal reaction at a temperature of 180℃ for 24h to obtain an intermediate product; centrifuging the intermediate product at 5000rpm for 8min to obtain a supernatant, and centrifuging the supernatant at 15000rpm for 10min to obtain particulate matter, and sonicating the particulate matter in isopropanol for 30min, and then centrifuging at 15000rpm for 10min. The carbon cloth was vacuum dried at 120℃ for 1 h to obtain MoS2 photosensitive material. The carbon cloth was then pretreated by ultrasonically cleaning it sequentially with acetone, ethanol, and ultrapure water for 30 min each. It was then immersed in a 3:1 (v / v) solution of H2SO4 and HNO3 for 30 min, followed by cleaning with ultrapure water until neutral. The cloth was then immersed in a 2% (w / w) aqueous solution of 3-aminopropyltriethoxysilane at 60℃ for 4 h to obtain pretreated carbon cloth. The pretreated carbon cloth was then mixed and modified by centrifuging it in a 2 mg / mL isopropanol solution at 500 rpm for 1 min, followed by centrifugation at 3000 rpm for 2 min to complete the preloading. The preloaded carbon cloth was then vacuum dried at 120℃ for 0.5 h to obtain the carbon cloth material.

[0105] Methods for modifying carbon felt include:

[0106] The carbon felt was pretreated by ultrasonically cleaning it sequentially with acetone, ethanol, and ultrapure water for 30 min each. Then, the carbon felt was immersed in a mixture of H2SO4 and HNO3 (volume ratio 3:1) for 30 min, followed by cleaning with ultrapure water until neutral. It was then placed in a drying oven at 60℃ for 12 h to obtain pretreated carbon felt. The pretreated carbon felt was then placed in a treatment solution, which was prepared by mixing 100 mL of ultrapure water, 2.70 g of FeCl3·6H2O, and 0.99 g of FeCl2·4H2O. N2 was introduced into the treatment solution, and magnetic stirring was performed at 500 rpm. 15 mL of ammonia water was added dropwise to the treatment solution at a rate of 1 mL / min. The treatment solution was then reacted at 80℃ for 1 h and vacuum dried at 60℃ for 12 h to obtain the carbon felt material.

[0107] Example 12: This example differs from Example 1 in that the modification method of the carbon cloth includes: adding 0.6g of sodium molybdate, 2g of thioacetamide, and 0.4g of L-cysteine ​​to 90mL of ultrapure water, and magnetically stirring for 30min to obtain a reaction solution; obtaining MoS2 photosensitive material; adding 1M hydrochloric acid to the reaction solution to adjust the pH to 4.1, and then transferring the reaction solution to a 100mL polytetrafluoroethylene liner for hydrothermal reaction at a temperature of 220℃ for 24h to obtain an intermediate product; centrifuging the intermediate product at 5000rpm for 10min to obtain a supernatant, and further centrifuging the supernatant at 15000rpm for 8min to obtain particulate matter; placing the particulate matter in isopropanol for sonication for 30min, and then centrifuging at 15000rpm for 8min. The carbon cloth was vacuum dried at 120℃ for 2 hours to obtain MoS2 photosensitive material. The carbon cloth was then pretreated by ultrasonically cleaning it sequentially with acetone, ethanol, and ultrapure water for 40 minutes each. Next, the carbon cloth was immersed in a 3:1 mixture of H2SO4 and HNO3 for 30 minutes, then cleaned with ultrapure water until neutral. It was then immersed in a 2% (w / w) aqueous solution of 3-aminopropyltriethoxysilane at 60℃ for 4 hours to obtain pretreated carbon cloth. The carbon cloth was then mixed and modified by centrifuging it in a 2 mg / mL isopropanol solution containing MoS2 photosensitive material for 2 minutes at 500 rpm, followed by 3 minutes at 3000 rpm to complete the preloading process. Finally, the preloaded carbon cloth was vacuum dried at 120℃ for 1.5 hours to obtain the carbon cloth material.

[0108] Methods for modifying carbon felt include:

[0109] The carbon felt was pretreated by ultrasonically cleaning it sequentially with acetone, ethanol, and ultrapure water for 40 min each. Then, the carbon felt was immersed in a mixture of H2SO4 and HNO3 (volume ratio 3:1) for 30 min, followed by cleaning with ultrapure water until neutral. It was then placed in a drying oven at 60℃ for 12 h to obtain pretreated carbon felt. The pretreated carbon felt was then placed in a treatment solution, which was prepared by mixing 100 mL of ultrapure water, 2.70 g of FeCl3·6H2O, and 0.99 g of FeCl2·4H2O. N2 was introduced into the treatment solution, and magnetic stirring was performed at 500 rpm. 15 mL of ammonia water was added dropwise to the treatment solution at a rate of 1 mL / min. The treatment solution was then reacted at 80℃ for 1 h and vacuum dried at 60℃ for 12 h to obtain the carbon felt material.

[0110] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for improving the rapid granulation and estrogen removal of sludge based on a dual-algae system, characterized in that, Includes the following steps: A dual-algae system is established; the dual-algae system includes a cathode chamber and an anode chamber, which are separated by gravel; the cathode chamber is equipped with a cathode and the anode chamber is equipped with an anode, the cathode and the anode are connected by titanium wire located outside the cathode chamber and the anode chamber, and a resistance box is installed on the titanium wire; the cathode is made of carbon cloth material and the anode is made of carbon felt material; the cathode chamber is filled with microalgae liquid that produces oxygen through photosynthesis, and the anode chamber is used to fill wastewater containing activated sludge to be granulated and estrogen, as well as microalgae liquid from the cathode chamber; Water was introduced into the anode chamber of the dual-algae system, with a wastewater to microalgae solution volume ratio of 80–90:

1. The cathode chamber was then illuminated for 8–16 hours at a light intensity of 80–260 μmol·s⁻¹. -1 ·m -2 During the illumination period, the anode chamber is aerated for 217-325 minutes, settled for 10-15 minutes, and drained for 2-3 minutes to complete the granulation of activated sludge to be granulated and the removal of estrogen from the wastewater. The carbon cloth material is a carbon cloth modified with molybdenum disulfide; the carbon felt material is a carbon felt loaded with Fe3O4 magnetic particles, with a Fe3O4 magnetic particle loading of 5.79 mg / cm³. 2 ; A magnetic coil is mounted on the anode chamber; The modification method of the carbon cloth includes: At a temperature of 25℃, add 0.2~0.6 g of sodium molybdate, 1~2 g of thioacetamide and 0.2~0.4 g of L-cysteine ​​to 70~90 mL of ultrapure water, and stir magnetically for 30 min at a stirring speed of 200~300 rpm to obtain the reaction solution. To obtain MoS2 photosensitive material, 1M hydrochloric acid was added to the reaction solution to adjust the pH to 3.9-4.

1. The reaction solution was then transferred to a 100mL polytetrafluoroethylene liner for hydrothermal reaction at 180-220℃ for 24 hours to obtain an intermediate product. The intermediate product was centrifuged at 5000 rpm for 8-10 minutes to obtain a supernatant. The supernatant was centrifuged at 15000 rpm for 8-10 minutes to obtain particulate matter. The particulate matter was ultrasonicated in isopropanol for 30 minutes, then centrifuged at 15000 rpm for 8-10 minutes and vacuum dried at 120℃ for 1-2 hours to obtain the MoS2 photosensitive material. The carbon cloth was pretreated by ultrasonically cleaning it with acetone, ethanol, and ultrapure water for 30-40 minutes each, then immersing it in a mixture of H2SO4 and HNO3 (volume ratio 3:1) for 30 minutes. The carbon cloth was then rinsed with ultrapure water until neutral, and finally soaked in a 2% (w / w) aqueous solution of 3-aminopropyltriethoxysilane at 60°C for 4 hours to obtain the pretreated carbon cloth. Mixed modification: The pretreated carbon cloth was placed in a MoS2 photosensitive material solution with a content of 2 mg / mL isopropanol, centrifuged at 500 rpm for 1-2 min, and then centrifuged at 3000 rpm for 2-3 min to complete the preloading, and then the preloaded carbon cloth was vacuum dried at 120℃ for 0.5-1.5 h to obtain the carbon cloth material. The modification method of the carbon felt includes: The carbon felt was pretreated by ultrasonically cleaning it with acetone, ethanol and ultrapure water for 30-40 min each, then immersing it in a mixture of H2SO4 and HNO3 (volume ratio 3:1) for 30 min, then washing it with ultrapure water until neutral, and then drying it at 60℃ for 12 h to obtain the pretreated carbon felt. Mixed modification; the pretreated carbon felt was placed in a treatment solution; the treatment solution was obtained by mixing 100 mL of ultrapure water, 2.70 g of FeCl3·6H2O and 0.99 g of FeCl2·4H2O; N2 was introduced into the treatment solution and magnetic stirring was performed at a speed of 500 rpm; 15 mL of ammonia water was added dropwise to the treatment solution at a drop rate of 1 mL / min; the treatment solution was then reacted at 80 °C for 1 h and vacuum dried at 60 °C for 12 h to obtain the carbon felt material.

2. The method for improving rapid sludge granulation and estrogen removal based on a dual-algae system as described in claim 1, characterized in that, The microalgae solution is an aqueous solution of green algae with an OD680 of 0.8~1, and the MLSS of the activated sludge to be granulated in the anode chamber is 2~4 g / L.

3. The method for improving rapid sludge granulation and estrogen removal based on a dual-algae system as described in claim 2, characterized in that, The green algae mentioned is Chlorella vulgaris.

4. The method for improving rapid sludge granulation and estrogen removal based on a dual-algae system as described in claim 1, characterized in that, The aeration rate is 2 L / min.

5. The method for improving rapid sludge granulation and estrogen removal based on a dual-algae system as described in claim 1, characterized in that, The temperature of both the cathode chamber and the anode chamber is 20~25℃.

6. The method for improving rapid sludge granulation and estrogen removal based on a dual-algae system as described in claim 1, characterized in that, During aeration, the anode chamber is illuminated with a light intensity of 120 μmol·s⁻¹. -1 ·m -2 .

7. The method for improving rapid sludge granulation and estrogen removal based on a dual-algae system as described in claim 1, characterized in that, The method for establishing the dual-algae system includes: S1. Assemble the cathode chamber and anode chamber, fill the connection between the cathode chamber and anode chamber with gravel for physical separation, and connect the cathode chamber and anode chamber through a connecting pipe with a peristaltic pump. S2. Carbon cloth material is used as the cathode and carbon felt material is used as the anode. The cathode is added to the cathode chamber and the anode is added to the anode chamber. A titanium wire with a resistor box in series is used to connect the cathode and the anode. S3. Microalgae solution is loaded into the cathode chamber, and wastewater containing activated sludge to be granulated and estrogen is loaded into the anode chamber. A lamp is installed in the cathode chamber for illumination, and an aeration device and magnetic coil are installed in the anode chamber. Oxygen is generated by illumination in the cathode chamber, and microalgae solution and activated sludge form bacterial-algae granular sludge in the anode chamber under the action of aeration. The dual-algae-bacterial system is established.

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