Biochar nitrogen and phosphorus removal composite material based on quorum sensing signal molecule slow release and metal modification as well as preparation method and application

Abstract

The invention discloses a biochar nitrogen and phosphorus removal composite material based on quorum sensing signal molecule slow release and metal modification as well as a preparation method and application thereof, and relates to the technical field of water treatment. According to the composite material disclosed by the invention, biochar is taken as a carrier, metal nanoparticles are loaded on the surface, and a PLGA sustained-release microcapsule embedded with AHL is compounded; the preparation method comprises the following three steps: preparation of the metal modified charcoal, preparation of the AHL-coated PLGA microcapsule and composite granulation. Through the synergistic effect of metal active site adsorption and AHL slow-release induced biodegradation, deep purification of nitrogen and phosphorus in the water body is realized, additional addition of a biological agent and a chemical phosphorus removal agent is not needed, the operation is simple, the operation cost is low, and environmental ecological and sanitary potential safety hazards are avoided. The composite material can be directly used as a filler to be applied to water treatment systems such as constructed wetlands and ecological ditches, is suitable for deep nitrogen and phosphorus removal of surface water and tail water of sewage treatment plants, and has good practical application value and popularization prospect.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, and in particular to a biochar denitrification and phosphorus removal composite material based on quorum sensing signal molecule slow release and metal modification, its preparation method, and its application. Background Technology

[0002] With increasingly stringent surface water environmental quality standards (such as GB 3838-2002 requiring Class II water to have TP ≤ 0.1 mg / L and TN ≤ 0.5 mg / L), deep nitrogen and phosphorus removal from wastewater has become a core challenge in the water treatment field. Traditional biological nitrogen and phosphorus removal processes generally face the dual constraints of sludge age conflict and carbon source competition: nitrifying bacteria require a long sludge age (>15 days) to maintain activity, while polyphosphate-accumulating bacteria require a short sludge age (about 3 days) to ensure phosphorus removal efficiency, resulting in insufficient simultaneous nitrogen and phosphorus removal efficiency during process compromise operation; in low C / N wastewater, denitrifying bacteria and polyphosphate-accumulating bacteria fiercely compete for volatile fatty acids as carbon sources, and the high concentration of nitrates in the returned sludge has an inhibitory effect on polyphosphate-accumulating bacteria, further exacerbating the imbalance problem of nitrogen and phosphorus removal.

[0003] To overcome this bottleneck, modified packing material technology has been extensively studied. Biochar, due to its wide availability, strong environmental sustainability, rich functional groups, and well-developed pore structure, is considered a highly promising packing matrix. However, biochar exhibits weak selectivity and limited adsorption capacity for phosphorus. While metal-supported biochar materials can enhance phosphorus removal capacity through physicochemical adsorption, they cannot simultaneously enhance biological nitrogen removal. Introducing typical quorum sensing signaling molecules, such as N-acyl-homoserine lactones (AHLs), can induce microbial aggregation to form biofilms and improve biological nitrogen removal efficiency. However, AHLs have a half-life of less than 24 hours in aqueous phase and are easily diffused and degraded, leading to frequent additions in practical applications, low utilization rates, and difficulty in achieving low-cost, long-term control.

[0004] Current technologies suffer from the following major drawbacks: First, there is a lack of synergy among functional materials. Physicochemical phosphorus removal materials (such as metal oxide support carriers) often inhibit microbial activity, while biological denitrification media (such as sulfur autotrophic denitrification media) lack phosphorus removal capabilities. No integrated material capable of simultaneous deep nitrogen and phosphorus removal has yet been developed. Second, AHL application stability is insufficient. AHL directly added to water is prone to hydrolysis of its ester bonds and degradation by acyl hydrolases (AiiA), making it difficult to maintain an effective concentration on the media surface. This results in slow biofilm formation and fluctuating denitrification efficiency. Third, system sustainability is poor. Traditional media require replacement or chemical regeneration after adsorption saturation, easily leading to secondary pollution. Furthermore, the denitrification process relies on external carbon sources, significantly increasing operating costs. Although patents and papers have attempted to utilize metal-modified biochar or hydrogels encapsulating biochar and AHL for nitrogen or phosphorus removal from water, these technologies have failed to solve the problem of stable co-loading of metal components and AHL, and have not achieved spatiotemporal synergy in nitrogen and phosphorus removal. Summary of the Invention

[0005] The purpose of this invention is to provide a biochar denitrification and phosphorus removal composite material based on quorum sensing signal molecule slow release and metal modification, as well as its preparation method and application, to solve the problems existing in the prior art.

[0006] To achieve the above objectives, the present invention provides the following solution: This invention provides a biochar denitrification and phosphorus removal composite material based on quorum sensing signal molecule sustained release and metal modification, using biochar as a carrier, wherein metal nanoparticles and sustained-release microcapsules encapsulating quorum sensing signal molecules are loaded on the carrier. The metal nanoparticles are selected from at least two of calcium, magnesium, and lanthanum; the quorum sensing signal molecule is... N -Acylhomoserine lactone (AHL); Furthermore, the aforementioned N -Acylhomoserine lactones are C6-HSL and C 10 - One or two of the HSLs.

[0007] Furthermore, the wall material of the sustained-release microcapsules is polylactic acid-glycolic acid copolymer (PLGA).

[0008] Furthermore, the loading of the metal nanoparticles is 5-20 wt% of the biochar mass.

[0009] Furthermore, the loading of the sustained-release microcapsules in the composite material is 30-50 μg / g.

[0010] Furthermore, the sustained-release microcapsules have the effect of N The coating rate of α-acylhomoserine lactone is 80-95%.

[0011] This invention also provides a method for preparing the above-mentioned biochar nitrogen and phosphorus removal composite material based on quorum sensing signal molecule sustained release and metal modification, comprising the following steps: (1) Biomass was immersed in a metal salt solution, washed until neutral, and then calcined to obtain metal nanoparticle modified biochar (MBC). (2) The solvent evaporation method of double emulsion is used to evaporate the solvent. N -Acylhomoserine lactone is embedded in polylactic acid-glycolic acid copolymer to form AHL@PLGA microcapsules; (3) The metal nanoparticle-modified biochar and the AHL@PLGA microcapsules are granulated together with an adhesive to obtain the biochar denitrification and phosphorus removal composite material based on quorum sensing signal molecule slow release and metal modification.

[0012] Furthermore, the internal aqueous phase in the double emulsion solvent evaporation method is 10-30 mM. N The solution consists of a dimethyl sulfoxide solution of α-acyl homoserine lactone, an oil phase of 5% (w / v) dichloromethane solution of polylactic acid-glycolic acid copolymer, and an aqueous phase of 2% (w / v) polyvinyl alcohol (PVA) solution. More specifically, the inner aqueous phase is injected into the oil phase at a volume ratio of 5% to form a primary emulsion by ultrasonication. The primary emulsion is then injected into the outer aqueous phase at a volume ratio of 5% and homogenized for 2 minutes to form a secondary emulsion. After magnetic stirring for 4 hours, the microspheres are collected by centrifugation and freeze-dried.

[0013] Furthermore, the mass ratio of the metal nanoparticle-modified biochar to the AHL@PLGA microcapsules is 10:1.

[0014] Furthermore, the composite granulation adopts a fluidized bed with an inlet air temperature of 40℃, an outlet air temperature of 32℃, an air velocity of 1.2 m³ / min, and an atomization pressure of 0.3 MPa, granulating to a particle size of 3-5 mm.

[0015] Furthermore, the adhesive is preferably a 5 wt% PVA solution.

[0016] Furthermore, the molar ratio of divalent metal to trivalent metal in the metal salt solution is 3:1.

[0017] The present invention further provides the application of the above-mentioned biochar denitrification and phosphorus removal composite material based on quorum sensing signal molecular slow release and metal modification in wastewater treatment; including its application as a filler in constructed wetlands and ecological ditch systems, with influent COD concentration ≤100 mg / L, TN concentration ≤20 mg / L, and TP concentration ≤5 mg / L.

[0018] This invention achieves a synergistic breakthrough in nitrogen and phosphorus removal. Through the synergistic design of metal active site modification and AHL slow-release system, compared with commercial activated carbon that adds AHL, the treatment efficiency of the material of this invention is significantly improved after 30 days of operation: TP removal rate increases from 56%~81% to 96%~99%, and TN removal rate increases from 58%~70% to 94%~95%. At the same time, compared with the traditional process of directly adding AHL, the slow-release performance of AHL in this invention is greatly optimized, and its effective period is extended from 4 days to 20~26 days, significantly reducing the consumption of AHL.

[0019] This invention eliminates the need for additional biological agents and chemical phosphorus removal agents, achieving a highly efficient and environmentally friendly purification mechanism. Utilizing the well-developed porous structure and abundant functional groups of biochar, combined with the selective adsorption of phosphorus by metal compounds and the synergistic effect of slow-release AHL inducing microbial biofilm formation and efficient nitrogen degradation, it achieves deep purification of nitrogen and phosphorus in water. This feature not only reduces operating costs but also simplifies the process, eliminating environmental and ecological risks and health and safety hazards.

[0020] The present invention is easy to operate and highly operable. It can play a role simply by placing the synchronous denitrification and phosphorus removal composite material as a filler directly into water treatment systems such as artificial wetlands and ecological ditches. It does not require complicated supporting equipment and operation and maintenance processes, making it easy to promote and apply in deep denitrification and phosphorus removal projects for surface water.

[0021] The present invention discloses the following technical effects: The composite material for simultaneous nitrogen and phosphorus removal prepared by this invention achieves a breakthrough in synergistic enhancement of nitrogen and phosphorus removal functions. Through the optimized coupling of metal active site modification and quorum sensing signal molecule (AHL) slow release system, the nitrogen and phosphorus purification efficiency and long-term stability of water bodies are significantly improved.

[0022] The material of this invention does not require the addition of biological agents and chemical phosphorus removal agents. Relying on the well-developed pore structure and rich functional groups of biochar itself, combined with the selective adsorption of phosphorus by metal compounds, and the synergistic mechanism of slow-release AHL inducing microorganisms to form biofilms and thus efficiently degrade nitrogen, it can achieve deep purification of nitrogen and phosphorus in water.

[0023] This invention not only simplifies water treatment operations and significantly reduces process operating costs, but also fundamentally avoids the environmental and ecological risks and hygiene and safety hazards that may be caused by chemical agents and exogenous microbial agents, exhibiting excellent environmental compatibility. Furthermore, this invention is convenient to apply and highly operable; the composite material can be directly used as a filler in various conventional water treatment systems such as constructed wetlands and ecological ditches, requiring no complex supporting equipment or cumbersome operation and maintenance processes. It is easily applied in large-scale engineering projects and has broad prospects and practical application value in the field of deep nitrogen and phosphorus removal from surface water. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 The powdered C6-HSL@PLGA / MBC1 and C in Example 1 of this invention 10 XRD pattern of -HSL@PLGA / MBC1.

[0026] Figure 2 The powdered C6-HSL@PLGA / MBC1 and C in Example 1 of this invention 10 FTIR spectra of -HSL@PLGA / MBC1.

[0027] Figure 3 The powdered C6-HSL@PLGA / MBC1 and C in Example 1 of this invention 10 SEM-EDS spectra of -HSL@PLGA / MBC1.

[0028] Figure 4 This is a schematic diagram showing the changes in TN (A), TP (B), and AHL (C) concentrations in the effluent of the control group and experimental group in Example 1 of the present invention.

[0029] Figure 5 This is a schematic diagram showing the changes in TN(A), TP(B), and AHL(C) concentrations in the effluent of the control group and experimental group in Example 2 of the present invention.

[0030] Figure 6 This is a schematic diagram showing the changes in TN(A), TP(B), and AHL(C) concentrations in the effluent of the AHL@PLGA / MBC3, MBC3, AHL@PLGA+BC3, and AHL+BC3 experimental groups in Example 3 of the present invention.

[0031] Figure 7 The adsorption capacities of nitrogen (A) and phosphorus (B) of AHL@PLGA / MBC3 under different temperature and pH conditions in Example 3 of this invention, as well as the concentrations (C) of different ions at equilibrium under different pH conditions at 25°C, are shown.

[0032] Figure 8 The nitrogen and phosphorus adsorption capacity and removal rate are shown in Example 3 of this invention during 5 adsorption-desorption cycles of AHL@PLGA / MBC3. Detailed Implementation

[0033] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0034] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0035] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0036] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0037] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0038] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0039] Example 1 This embodiment provides a composite material for simultaneous nitrogen and phosphorus removal, and the preparation steps are as follows: (1) Preparation of metal-modified biochar 110.3 g CaCl2·2H2O and 88.3 g LaCl3·7H2O (Ca / La molar ratio of 3:1) were dissolved in deionized water and the solution was brought to a final volume of 1000 mL to obtain a mixed metal salt solution with a concentration of 1.0 mol / L. Subsequently, 100 g of corn stalks were completely immersed in the above-mentioned metal salt solution, and the pH of the system was adjusted to 10 with 0.1 M NaOH solution. The mixture was then immersed at a constant temperature of 60℃ and 150 rpm for 12 h. After immersion, the modified biomass material was repeatedly washed by vacuum filtration with deionized water until the wash liquid was neutral. Then, it was placed in a tube furnace and heated to 500℃ at a rate of 5℃ / min under a nitrogen (N2) atmosphere (N2 flow rate of 100 mL / min). The mixture was then kept at this temperature for 2 h for pyrolysis. After cooling, calcium / lanthanum (Ca / La) modified corn stalk biochar was obtained, denoted as MBC1, in which the total loading of Ca and La metal nanoparticles was 10% of the biochar mass.

[0040] (2) Preparation of AHL@PLGA microcapsules Prepare 10 mM C6-HSL dimethyl sulfoxide solutions and C 10 1 mL each of C6-HSL dimethyl sulfoxide solution and C... Simultaneously, prepare 20 mL of a 5% (w / v) polylactic acid-glycolic acid copolymer dichloromethane solution (PLGA dichloromethane solution), and divide it into two equal portions of 10 mL each. Then, separately... 10 -HSL dimethyl sulfoxide solution was slowly injected into the corresponding PLGA dichloromethane solution, and ultrasonicated for 30 seconds under ultrasonic power of 50 W and pulse mode (1 s on / 1 s off) to form a colostrum; Separately, 200 mL of a 2% (w / v) polyvinyl alcohol (PVA) aqueous solution was used as the external aqueous phase. The above primary emulsion was added to it at a volume ratio of 5%, and the mixture was homogenized and emulsified at 8000 rpm for 2 min to form a stable double emulsion system. The double emulsion was then continuously stirred on a magnetic stirrer for 4 h to allow the organic solvent to fully evaporate. The resulting microspheres were collected by centrifugation and freeze-dried to obtain AHL@PLGA microcapsules, namely C6-HSL@PLGA microcapsules and C... 10 -HSL@PLGA microcapsules, containing C6-HL and C 10 - The coverage rates of HSL reached 95% and 80%, respectively.

[0041] (3) Composite granulation 90 g of MBC1 was mixed with 9 g of C6-HSL@PLGA and 9 g of C 10HSL@PLGA microcapsules were placed in a fluidized bed granulator, and a 5 wt% PVA aqueous solution was sprayed in as a binder. The fluidized bed operating parameters were set as follows: inlet air temperature 40℃, outlet air temperature 32℃, and air velocity 1.2 m. 3 / min, atomization pressure 0.3 MPa. Continuous granulation until the particle size reaches 3-5 mm yields two simultaneous nitrogen and phosphorus removal composite materials, denoted as C6-HSL@PLGA / MBC1 and C... 10 -HSL@PLGA / MBC1, in which microcapsules C6-HSL@PLGA and C 10 The loadings of -HSL@PLGA in the composites were 42 μg / g and 30 μg / g, respectively.

[0042] Figure 1 , Figure 2 and Figure 3 They are powdered C6-HSL@PLGA / MBC1 and C 10 XRD patterns, FTIR patterns, and SEM-EDS spectra of the HSL@PLGA / MBC1 composite material were used to characterize and analyze the phase composition, chemical structure, and microstructure of the material.

[0043] like Figure 1 The XRD structure analysis results show that the synthesized C6-HSL@PLGA / MBC1 and C 10 The diffraction peaks of the HSL@PLGA / MBC1 powder sample are highly consistent with the characteristic peaks of La(OH)3 and CaCO3 on the PDF 44-0141 standard card. This result directly proves the successful synthesis of Ca / La modified biochar.

[0044] Further analysis of the sample's chemical structure using FTIR spectra revealed that the position and intensity of characteristic peaks directly reflect the substance's structural composition. Figure 2 As can be observed, the FTIR spectra of both composite materials exhibit typical characteristic absorption peaks: 1313 cm⁻¹. -1 1392 cm -1 The peak at 712 cm⁻¹ represents the stretching vibration of the CO bond in carbonates. -1 874 cm -1 The peak at 1530 cm⁻¹ represents the stretching vibration of the metal-oxygen bond (MO). -1 The peak at 1772 cm⁻¹ represents the bending vibration peak of NH in amide II. -1 The peaks at this location represent the stretching vibrations of C=O in lactone compounds. The presence of these characteristic peaks indicates that the AHL@PLGA / MBC1 composite material has been successfully prepared.

[0045] Figure 3The SEM-EDS spectra revealed the microstructure and elemental distribution of the two composite materials. The SEM images showed that the metal compounds were uniformly distributed on the biochar surface in the form of nanoparticles, without significant agglomeration. Combined with the elemental distribution diagrams, it was found that lanthanum (La) and calcium (Ca) were uniformly distributed on the material surface, further confirming the presence of C6-HSL@PLGA / MBC1 and C... 10 The HSL@PLGA / MBC1 composite material was successfully synthesized, and the functional components were uniformly dispersed in the material.

[0046] Performance verification: Four PVC adsorption columns were constructed, each a cylinder with a diameter of 2 cm and a height of 10 cm. Slatted screens were installed at both the top and bottom of the columns to filter artificially simulated wastewater. The simulated wastewater had the following water quality conditions: COD concentration of 100.3 ± 7.2 mg / L, NH4+ concentration of... + The concentrations of -N were 9.6±0.1 mg / L, TN was 18.2±2.5 mg / L, TP was 4.8±0.7 mg / L, and the pH was 7.1±0.5. In the experimental procedure, wastewater was first stored in a storage tank, then treated by the adsorption column and collected in a filtrate tank. A Lange peristaltic pump was used to transport the wastewater at a flow rate of 2 mL / min. Based on a packing height of 2 cm, the hydraulic retention time (HRT) of the adsorption column was approximately 3.1 min.

[0047] The adsorption column packings were divided into two types: the two experimental groups were filled with C6-HSL@PLGA / MBC1 and C, respectively. 10 Two simultaneous nitrogen and phosphorus removal composite materials, C6-HSL@PLGA / MBC1, were used. Two control groups were filled with commercially available activated carbon (iodine value 1000, particle size 4 mm), with a filling height of 2 cm for all fillers. On day 0 of the experiment, 0.01 mol of C6-HSL and C6-MBC1 were added to the commercially available activated carbon fillers in both control groups, respectively. 10 -HSL, labeled as follows: Control group C-C6-HSL (commercial activated carbon + C6-HSL), CC 10 -HSL (Commercial Activated Carbon + C) 10 -HSL); experimental group C6-HSL@PLGA / MBC1, C 10 -HSL@PLGA / MBC1. The experiment lasted for 30 days, during which the concentrations of TN, TP, and AHL in the effluent of each group were continuously monitored.

[0048] Figure 4 The following is a schematic diagram showing the changes in TN, TP, and AHL concentrations in the effluent of the four groups over time. Comparison of TN and TP removal effects: Adding C6-HSL and C 10For the first 10 days, the TN (total nitrogen) and TP (total phosphorus) concentrations in the effluent from the two commercial activated carbon groups of -HSL remained stable at approximately 5.5 mg / L and 0.06 mg / L, respectively, corresponding to TN and TP removal rates of approximately 70% and 99%, respectively. Subsequently, the TN and TP concentrations in the effluent from the commercial activated carbon groups continued to rise until the TN removal rate was completely lost by day 30, and the TP removal rate decreased to 56%. Meanwhile, the C6-HSL@PLGA / MBC1 and C... 10 The TN concentration in the effluent of the C6-HSL@PLGA / MBC1 experimental group decreased continuously from 5.6 mg / L to 0.82 mg / L and 1.07 mg / L within 30 days, corresponding to removal rates of 95% and 94%, respectively; the TP concentration in the effluent remained within 0.18 mg / L and 0.06 mg / L within 30 days, corresponding to removal rates of 96% and 99%, respectively. These results indicate that C6-HSL or C6-MBC1 treatment significantly improves efficiencies and reduces TN concentrations. 10 - HSL-encapsulated and Ca / La metal-loaded modified biochar can significantly improve the removal efficiency of TN and TP in water.

[0049] Furthermore, the changes in effluent AHL concentration showed that AHL in the control group, which was supplemented with C6-HSL and C10-HSL respectively, became undetectable after 4 days. However, the effluent AHL concentration in the experimental groups, namely C6-HSL@PLGA / MBC1 and C10-HSL@PLGA / MBC1, remained at a high level for the first 14 days, and then became undetectable on the 22nd and 24th days, respectively. This indicates that C6-HSL@PLGA / MBC1 and C10-HSL@PLGA / MBC1 have good AHL sustained-release performance.

[0050] Example 2 This embodiment provides a composite material for simultaneous nitrogen and phosphorus removal, and the preparation steps are as follows: (1) Preparation of metal-modified biochar 152.5 g of MgCl2・6H2O and 88.3 g of LaCl3・7H2O (Mg / La molar ratio of 3:1) were dissolved in deionized water and the solution was brought to a final volume of 1000 mL to obtain a mixed metal salt solution with a concentration of 1.0 mol / L. Subsequently, 100 g of wheat straw was completely immersed in the above metal salt solution, and the pH of the system was adjusted to 10 with 0.1 M NaOH solution. The mixture was then immersed at a constant temperature of 60 °C and 150 rpm for 12 h. After immersion, the modified biomass material was repeatedly washed by vacuum filtration with deionized water until the wash liquid was neutral. Then, it was placed in a tube furnace and heated to 500 °C at a rate of 5 °C / min under a nitrogen (N2) atmosphere (N2 flow rate of 100 mL / min). The mixture was then kept at this temperature for 2 h for pyrolysis. After cooling, magnesium / lanthanum (Mg / La) modified wheat straw biochar was obtained, denoted as MBC2, in which the total loading of Mg and La metal nanoparticles was 5% of the biochar mass.

[0051] (2) Preparation of AHL@PLGA microcapsules Prepare 30 mM C6-HSL and C 10 1 mL of a C6-HSL mixture (molar ratio 1:1) and a dimethyl sulfoxide solution were prepared, along with 10 mL of a 5% (w / v) polylactic acid-glycolic acid copolymer dichloromethane solution (PLGA dichloromethane solution). Then, the above C6-HSL was mixed with C... 10 A 2-HSL mixed dimethyl sulfoxide solution was slowly injected into a PLGA dichloromethane solution and sonicated for 30 seconds under ultrasonic power of 50W and pulse mode (1 s on / 1 s off) to form a primary emulsion. Separately, 200 mL of 2% (w / v) polyvinyl alcohol (PVA) aqueous solution was used as the external aqueous phase, and the above primary emulsion was added to it at a volume ratio of 5%. The mixture was homogenized and emulsified at 8000 rpm for 2 min to form a stable secondary emulsion system. The secondary emulsion was then continuously stirred on a magnetic stirrer for 4 h to allow the organic solvent to fully evaporate. The resulting microspheres were collected by centrifugation and freeze-dried to obtain AHL@PLGA microcapsules (C6-HSL / C6-H2O). 10 -HSL@PLGA microcapsules), where C6-HSL / C 10 -HSL has a coverage rate of 86%.

[0052] (3) Composite granulation 90 g of MBC2 and 9 g of AHL@PLGA microcapsules were placed in a fluidized bed granulator, and a 5 wt% PVA aqueous solution was sprayed in as a binder. The fluidized bed operating parameters were set as follows: inlet air temperature 40℃, outlet air temperature 32℃, and air velocity 1.2 m. 3The atomization pressure was 0.3 MPa. Granulation was continued until the particle size reached 3-5 mm, thus obtaining the simultaneous denitrification and phosphorus removal composite material, denoted as AHL@PLGA / MBC2, in which the loading of microcapsules AHL@PLGA in the composite material was 45 μg / g.

[0053] Performance verification: Two PVC adsorption columns were constructed. Each column was a cylinder with a diameter of 2 cm and a height of 10 cm. Slatted screens were installed at the top and bottom of the columns to filter effluent from a wastewater treatment plant (water quality conditions: COD concentration 58.2 mg / L, NH4+). + The concentrations of -N were 2.9 mg / L, TN was 13.5 mg / L, TP was 1.2 mg / L, and pH was 6.8. The effluent was stored in a storage tank before adsorption and collected in a filtrate tank after adsorption. The adsorption column was filled with AHL@PLGA / MBC2 composite material for simultaneous nitrogen and phosphorus removal (experimental group) and commercial activated carbon (control group) (iodine value 1000, particle size 4.0 mm), respectively. The packing height was 5 cm, and a peristaltic pump was used to transport the effluent at a flow rate of 2 mL / min. On day 0, 0.01 mol of C6-HSL and C... were added to the packing of the commercial activated carbon group. 10 -HSL mixture (molar ratio 1:1), the control group and experimental group were denoted as C-AHL and AHL@PLGA / MBC2, respectively. The concentrations of TN, TP and total AHL in the effluent were monitored for 30 consecutive days.

[0054] Figure 5 This is a schematic diagram showing the changes in TN, TP, and AHL concentrations in the effluent of the control and experimental groups over time. (Addition of C6-HSL and C...) 10 The commercially available activated carbon group with C6-HSL mixture maintained stable TN and TP concentrations in the effluent at approximately 5.6 mg / L and 0.23 mg / L, respectively, over 30 days, corresponding to TN and TP removal rates of approximately 58% and 81%, respectively. In contrast, the AHL@PLGA / MBC2 experimental group showed a continuous decrease in TN concentration from 4.7 mg / L to 0.7 mg / L over 30 days, corresponding to a removal rate of 95%; the TP concentration remained stable at approximately 0.01 mg / L over 30 days, corresponding to a removal rate of 99%. Therefore, the modified biochar with AHL encapsulation and MgLa metal loading significantly promotes the removal rates of TN and TP. Furthermore, changes in effluent AHL concentration indicate that the addition of C6-HSL and C... 10 In the control group of the -HSL mixture, AHL was undetectable in the effluent after 4 days, while the AHL@PLGA / MBC2 experimental group maintained a high concentration of AHL in the effluent for the first 16 days, and then became undetectable after the 26th day, indicating that AHL@PLGA / MBC2 has good AHL sustained-release performance.

[0055] Example 3 This embodiment provides a composite material for simultaneous nitrogen and phosphorus removal, and the preparation steps are as follows: (1) Preparation of metal-modified biochar Dissolve 76.25 g MgCl2·6H2O, 55.15 g CaCl2·2H2O, and 88.3 g LaCl3·7H2O in deionized water (M 2+ With M 3+ A mixed metal salt solution with a molar ratio of 3:1 was prepared and diluted to 1000 mL to obtain a concentration of 1.0 mol / L. Subsequently, 100 g of the dehydrated residual sludge was completely immersed in the above metal salt solution, and the pH of the system was adjusted to 10 with 0.1 M NaOH solution. The solution was then subjected to constant temperature shaking at 60℃ and 150 rpm for 12 h. After impregnation, the modified biomass material was repeatedly washed with deionized water until the wash liquid was neutral. Then, it was placed in a tube furnace and heated to 500℃ at a rate of 5℃ / min under a nitrogen (N2) atmosphere (N2 flow rate of 100 mL / min). The temperature was maintained at this temperature for 2 h for pyrolysis. After cooling, calcium / magnesium / lanthanum (Ca / Mg / La) modified sludge biochar was obtained, denoted as MBC3, in which the total loading of Ca, Mg, and La metal nanoparticles was 20% of the biochar mass.

[0056] (2) Preparation of AHL@PLGA microcapsules Prepare 30 mM C6-HSL and C 10 Prepare 1 mL of a C6-HSL mixed dimethyl sulfoxide solution (molar ratio 2:1), and simultaneously prepare 10 mL of a 5% (w / v) polylactic acid-glycolic acid copolymer dichloromethane solution (PLGA dichloromethane solution). Then, mix the above C6-HSL with C... 10 A 2-HSL mixed dimethyl sulfoxide solution was slowly injected into a PLGA dichloromethane solution and sonicated for 30 s under ultrasonic power of 50W and pulse mode (1 s on / 1 s off) to form a primary emulsion. Separately, 200 mL of 2% (w / v) polyvinyl alcohol (PVA) aqueous solution was used as the external aqueous phase, and the above primary emulsion was added to it at a volume ratio of 5%. The mixture was homogenized and emulsified at 8000 rpm for 2 min to form a stable secondary emulsion system. The secondary emulsion was then continuously stirred on a magnetic stirrer for 4 h to allow the organic solvent to fully evaporate. The resulting microspheres were collected by centrifugation and freeze-dried to obtain AHL@PLGA microcapsules (C6-HSL / C6-H2O). 10 -HSL@PLGA microcapsules), where C6-HSL / C 10 -HSL has a coverage rate of 92%.

[0057] (3) Composite granulation 90 g of MBC3 and 9 g of AHL@PLGA microcapsules were placed in a fluidized bed granulator, and a 5 wt% PVA aqueous solution was sprayed in as a binder. The fluidized bed operating parameters were set as follows: inlet air temperature 40℃, outlet air temperature 32℃, and air velocity 1.2 m. 3 The atomization pressure was 0.3 MPa. Granulation was continued until the particle size reached 3-5 mm, thus obtaining the simultaneous denitrification and phosphorus removal composite material, denoted as AHL@PLGA / MBC3, in which the loading of microcapsules AHL@PLGA in the composite material was 50 μg / g.

[0058] Four PVC adsorption columns were constructed. Each column was a cylinder with a diameter of 2 cm and a height of 10 cm. Slatted screens were installed at the top and bottom of the columns to filter effluent from a wastewater treatment plant (water quality conditions: COD concentration 58.2 mg / L, NH4+). + The concentrations were: -N 2.9 mg / L, TN 13.5 mg / L, TP 1.2 mg / L, and pH 6.8. The effluent was stored in a storage tank before adsorption and collected in a filtrate tank after adsorption. The adsorption column was filled with AHL@PLGA / MBC3 composite material for simultaneous nitrogen and phosphorus removal, Ca / Mg / La-modified sludge biochar (MBC3), and AHL-encapsulated microcapsules (C6-HSL and C...). 10 -HSL molar ratio of 2:1) and unloaded metal sludge biochar (AHL@PLGA+BC3), and AHL directly mixed with unloaded metal sludge biochar (AHL+BC3). Among them, AHL@PLGA+BC3 consists of AHL-encapsulated microcapsules (C6-HSL and C) 10 AHL+BC3 is obtained by directly mixing AHL (C6-HSL molar ratio of 2:1) and unloaded metal sludge biochar (BC3) at a mass ratio of 1:10; AHL+BC3 is AHL (C6-HSL and C 10 A direct mixing system of C6-HSL (at a molar ratio of 2:1) and unloaded sludge biochar (BC3) was used, with a mass ratio of AHL to BC3 of 1:10. The packing height was 5 cm, and a peristaltic pump was used to transport the effluent at a flow rate of 2 mL / min. On day 0, 0.01 mol of C6-HSL and C6-BC3 were added to the packing of the AHL+BC3 group. 10 -HSL mixture (molar ratio of 2:1), monitor the total concentrations of TN, TP and AHL in the effluent for 30 consecutive days.

[0059] Figure 6This diagram illustrates the changes in TN, TP, and AHL concentrations in the effluent of the AHL@PLGA / MBC3, MBC3, AHL@PLGA+BC3, and AHL+BC3 experimental groups. Compared to the MBC3 group (without AHL encapsulation and only metal modification), the BC3 group (with AHL microcapsules and without metal modification), and the BC3 group (with direct AHL addition and without metal modification), the simultaneous nitrogen and phosphorus removal composite material in this invention exhibits better TN and TP removal rates (95% and 99%, respectively). The MBC3 group only possesses excellent phosphorus removal performance (99%) but extremely poor nitrogen removal performance (0.1%); the AHL@PLGA+BC3 group possesses excellent nitrogen removal performance (93%) but extremely poor phosphorus removal performance (2.5%); the AHL+BC3 group has poor nitrogen and phosphorus removal performance (55.6% and 0.83%, respectively). Furthermore, the AHL@PLGA / MBC3 experimental group maintained a high AHL concentration in the effluent for the first 22 days, and then became undetectable after day 28, indicating that AHL@PLGA / MBC3 has good AHL slow-release performance; AHL@PLGA+BC3 also had a 22-day AHL slow-release performance; while the AHL+BC3 experimental group with direct exogenous AHL addition only showed AHL detection for the first 6 days. These results indicate that the integrated multifunctional material combining AHL-encapsulated microcapsules and metal-modified biochar can significantly improve nitrogen and phosphorus removal efficiency and effectively prolong the AHL slow-release period.

[0060] To further verify the environmental adaptability and cyclic adsorption performance of AHL@PLGA / MBC3, the TP concentration in the effluent from the aforementioned wastewater treatment plant was adjusted to 5 mg / L. Nitrogen and phosphorus adsorption performance tests were conducted at temperatures of 15℃, 25℃, and 35℃, and pH values ​​of 5, 6, 7, 8, and 9. The amount of metal leaching after adsorption equilibrium in solutions at different pH values ​​at 25℃ was also measured. At 25℃ and pH 6, nitrogen and phosphorus were eluted using a mixed solution of 1 M NaOH and Na2CO3. Adsorption experiments were then performed in the effluent solution with a TP concentration of approximately 5 mg / L and a TN concentration of 13.5 mg / L. The above steps were repeated five times, and the nitrogen and phosphorus removal rates and adsorption capacity before and after the reaction were measured. Figure 7 As shown, with increasing temperature, nitrogen adsorption performance first increases and then decreases, while phosphorus adsorption performance gradually increases; with increasing pH, nitrogen adsorption performance gradually strengthens, while phosphorus adsorption performance first strengthens and then weakens. Within the temperature range of 15℃ to 35℃ and the pH range of 5 to 9, the adsorption capacities for nitrogen and phosphorus are 11.7–16.5 mg / g and 62.3–85.8 mg / g, respectively, both exhibiting superior nitrogen and phosphorus adsorption performance. Furthermore, at 25℃, with increasing pH, the amount of Ca dissolved after saturation adsorption... 2+ Mg 2+ and La 3+The concentrations were 4.35–7.59 mg / L, 2.8–5.3 mg / L, and 0.01–0.04 mg / L, respectively, all within the national standard safety range. Figure 8 As shown, with the increase of adsorption-desorption cycles, the adsorption capacities of nitrogen and phosphorus gradually decreased. The nitrogen adsorption capacity and removal rate significantly decreased from 10.7 mg / g and 82.7% in the third cycle to 6.2 mg / g and 61.6% in the fourth cycle; the phosphorus adsorption capacity and removal rate significantly decreased from 59.6 mg / g and 85.6% in the fourth cycle to 32.6 mg / g and 58.5% in the fifth cycle. In conclusion, AHL@PLGA / MBC3 exhibits excellent environmental adaptability and cyclic adsorption performance.

[0061] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A biochar nitrogen and phosphorus removal composite material based on quorum sensing signal molecule slow release and metal modification, characterized in that, Using biochar as a carrier, the carrier is loaded with metal nanoparticles and sustained-release microcapsules containing quorum sensing signal molecules; The metal nanoparticles are selected from at least two of calcium, magnesium and lanthanum; the quorum sensing signal molecule is N-acylhomoserine lactone.

2. The biochar nitrogen and phosphorus removal composite material based on quorum sensing signal molecule slow release and metal modification according to claim 1, characterized in that, The N-acylhomoserine lactone is C6-HSL and C 10 - One or two of the HSLs.

3. The biochar nitrogen and phosphorus removal composite material based on quorum sensing signal molecule slow release and metal modification according to claim 1, characterized in that, The wall material of the sustained-release microcapsules is polylactic acid-hydroxyacetic acid copolymer.

4. The biochar nitrogen and phosphorus removal composite material based on quorum sensing signal molecule slow release and metal modification according to claim 1, characterized in that, The loading of the metal nanoparticles is 5-20 wt% of the biochar mass.

5. The biochar nitrogen and phosphorus removal composite material based on quorum sensing signal molecule slow release and metal modification according to claim 1, characterized in that, The loading of the sustained-release microcapsules in the composite material is 30-50 μg / g.

6. The biochar nitrogen and phosphorus removal composite material based on quorum sensing signal molecule slow release and metal modification according to claim 1, characterized in that, The sustained-release microcapsules N The coating rate of α-acylhomoserine lactone is 80-95%.

7. The method for preparing the biochar denitrification and phosphorus removal composite material based on quorum sensing signal molecule sustained release and metal modification as described in any one of claims 1-6, characterized in that, Includes the following steps: (1) Biomass was immersed in a metal salt solution, washed until neutral, and then calcined to obtain metal nanoparticle-modified biochar; (2) The solvent evaporation method of double emulsion is used to evaporate the solvent. N -Acylhomoserine lactone is embedded in polylactic acid-glycolic acid copolymer to form AHL@PLGA microcapsules; (3) The metal nanoparticle-modified biochar and the AHL@PLGA microcapsules are granulated together with an adhesive to obtain the biochar denitrification and phosphorus removal composite material based on quorum sensing signal molecule slow release and metal modification.

8. The preparation method according to claim 7, characterized in that, The calcination is carried out under a protective atmosphere at a temperature of 400-700℃ for 1-3 hours; the internal aqueous phase of the double emulsion solvent evaporation method is... N The solution consists of a dimethyl sulfoxide solution of α-acyl homoserine lactone, an oil phase of a dichloromethane solution of polylactic acid-hydroxyacetic acid copolymer, and an aqueous solution of polyvinyl alcohol.

9. The preparation method according to claim 7, characterized in that, The molar ratio of divalent metal to trivalent metal in the metal salt solution is 3:

1.

10. The application of the biochar denitrification and phosphorus removal composite material based on quorum sensing signal molecule slow release and metal modification as described in any one of claims 1-6 in wastewater denitrification and phosphorus removal treatment.

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