A waste aerated concrete composite phosphorus removal wetland substrate and a method for preparing and using the same

Abstract

The application provides a kind of waste aerated concrete composite phosphorus removal wetland substrate and its preparation and application method, relating to artificial wetland water treatment and solid waste resource utilization technical field.The composite phosphorus removal substrate includes waste aerated concrete particles, ceramsite and zeolite, and the mass ratio of the three is 3:1:1.In preparation, waste aerated concrete is crushed and sieved, and waste aerated concrete particles, ceramsite and zeolite are washed and dried respectively, and then mixed according to the mass ratio.In application, the obtained composite phosphorus removal substrate is filled in the artificial wetland bed to form a composite phosphorus removal substrate layer, and the phosphorus-containing water flows through the composite phosphorus removal substrate layer.The composite substrate uses the pores and calcium-containing components of waste aerated concrete to fix phosphorus, and through ceramsite and zeolite to supplement the particle skeleton and pore interface, which can be used for phosphorus-containing water treatment, and at the same time realizes the resource utilization of waste aerated concrete.

Description

Technical Field

[0001] This invention relates to the fields of constructed wetland water treatment and solid waste resource utilization, and particularly to a waste aerated concrete composite phosphorus removal matrix and its preparation and application methods. Background Technology

[0002] Phosphorus is a major factor contributing to eutrophication of water bodies. Constructed wetlands are used for the purification of domestic sewage, wastewater treatment plant effluent, and agricultural non-point source water bodies due to their ease of operation and maintenance and low treatment costs. In constructed wetlands, the substrate not only forms the filling framework of the wetland bed but also participates in phosphorus removal through adsorption, ion exchange, and precipitation reactions. Therefore, the material composition and particle structure of the substrate directly affect the phosphorus removal efficiency.

[0003] Existing constructed wetlands commonly use river sand, gravel, ceramsite, and zeolite as substrates. River sand and gravel mainly serve as fillers and supports, but their phosphorus fixation capacity is limited; ceramsite has a certain porosity and particle stability, but its adsorption capacity is limited when used alone; zeolite has pores and ion exchange properties, but its direct phosphorus fixation capacity is still insufficient. Therefore, a single substrate usually cannot simultaneously achieve both phosphorus adsorption capacity and the particle support function of the substrate layer.

[0004] Waste aerated concrete has a porous structure and contains components such as calcium, silicon, and aluminum, making it suitable for use as a phosphorus removal material. However, when used alone, its material composition and particle state are relatively simple, and waste aerated concrete from different sources varies in particle size and surface impurities. Current technology lacks a technical solution for compounding waste aerated concrete, ceramsite, and zeolite in a defined ratio, and combining this with appropriate pretreatment and constructed wetland filling methods to form a composite phosphorus removal matrix.

[0005] Therefore, a composite phosphorus removal matrix for waste aerated concrete and its preparation and application methods are proposed. Summary of the Invention

[0006] In view of this, the present invention provides a waste aerated concrete composite phosphorus removal wetland matrix and its preparation and application method, so as to solve or alleviate the technical problems existing in the prior art, and at least provide a beneficial option.

[0007] The technical objective of this invention is to construct a composite phosphorus removal wetland matrix for waste aerated concrete, and to improve the purification efficiency of phosphorus-containing water bodies and realize the resource utilization of waste aerated concrete through matrix screening, compound optimization and artificial wetland application.

[0008] To achieve the above technical objectives, this invention is implemented according to the process of "matrix screening and pretreatment - composite matrix construction and optimization - constructed wetland construction and operation - performance verification and operation evaluation - technical effect"; wherein, the screening stage is used to determine the compatible materials, the optimization stage is used to determine the optimal mass ratio, the application stage is used to form a stable reaction layer, and the evaluation stage is used to verify the phosphorus removal performance and operational suitability.

[0009] The technical solution of this invention is implemented as follows: a waste aerated concrete composite phosphorus removal wetland matrix, comprising waste aerated concrete particles, ceramsite, and zeolite. The waste aerated concrete particles, ceramsite, and zeolite maintain their particle morphology and are mixed together. The mass ratio of waste aerated concrete particles, ceramsite, and zeolite is 3:1:1, which corresponds to a GTF311 composite matrix.

[0010] Waste aerated concrete particles serve as the main calcium-containing and porous component in the composite phosphorus removal matrix, providing a porous interface for contact with phosphorus-containing water and phosphorus fixation reaction sites. Ceramsite is dispersed between the waste aerated concrete particles to supplement the particle skeleton of the composite matrix. Zeolite is dispersed between the waste aerated concrete particles and ceramsite to provide channels and ion exchange interfaces. The three particulate materials are combined in a 3:1:1 mass ratio, maintaining a high proportion of waste aerated concrete in the composite matrix while retaining the roles of ceramsite and zeolite in particle structure and interface composition.

[0011] Furthermore, the waste aerated concrete particles are obtained by crushing and screening waste aerated concrete materials.

[0012] Furthermore, the particle size of the waste aerated concrete particles is 1–8 mm, while the particle size of the ceramsite and zeolite is 2–4 mm.

[0013] Furthermore, the particle size of the waste aerated concrete particles is 1–4 mm.

[0014] Furthermore, the particle size of the waste aerated concrete particles is 1–2 mm.

[0015] Furthermore, the waste aerated concrete particles, ceramsite, and zeolite were all particles that had been successively washed with tap water, rinsed with distilled water, and dried.

[0016] This invention also provides a method for preparing a composite phosphorus removal wetland substrate made from waste aerated concrete, comprising the following steps: S1. The waste aerated concrete material is crushed and screened to obtain waste aerated concrete particles, and the ceramsite and zeolite are screened separately. S2. Clean the waste aerated concrete particles, ceramsite, and zeolite separately. S3. Dry the cleaned waste aerated concrete particles, ceramsite, and zeolite respectively. S4. The dried waste aerated concrete particles, ceramsite and zeolite are mixed in a mass ratio of 3:1:1 to obtain the waste aerated concrete composite phosphorus removal wetland matrix.

[0017] In step S1, the waste aerated concrete material is crushed and screened into waste aerated concrete particles with a particle size of 1 to 8 mm, and the ceramsite and zeolite are screened into particles with a particle size of 2 to 4 mm.

[0018] In step S2, the waste aerated concrete particles, ceramsite, and zeolite are first rinsed with tap water to remove dust and impurities adhering to the particle surface, and then the waste aerated concrete particles, ceramsite, and zeolite are rinsed with distilled water.

[0019] In step S3, the washed waste aerated concrete particles, ceramsite, and zeolite are dried at 150 °C for 8 h. By washing and drying different raw materials separately, the influence of surface deposits and moisture content on the mass ratio can be reduced.

[0020] In step S4, the waste aerated concrete particles, ceramsite, and zeolite maintain their respective particle shapes during the mixing process, and the three particulate materials are dispersed in the composite phosphorus removal matrix.

[0021] This invention also provides a method for applying waste aerated concrete composite phosphorus removal wetland substrate, comprising the following steps: A1. Waste aerated concrete particles, ceramsite and zeolite are mixed in a mass ratio of 3:1:1 to obtain a composite phosphorus removal matrix, and the composite phosphorus removal matrix is ​​filled into the artificial wetland bed to form a composite phosphorus removal matrix layer. A2. Introduce phosphorus-containing water into the constructed wetland bed, allowing the phosphorus-containing water to flow through the composite phosphorus removal matrix layer and come into contact with waste aerated concrete particles, ceramsite, and zeolite. A3. Discharge the water that has flowed through the composite phosphorus removal matrix layer from the constructed wetland bed.

[0022] Furthermore, the total phosphorus concentration when phosphorus-containing water enters the constructed wetland bed is 1–20 mg / L.

[0023] Furthermore, the particle size of the waste aerated concrete particles used to form the composite phosphorus removal matrix layer is 1–2 mm, and the particle size of the ceramsite and zeolite is 2–4 mm.

[0024] Furthermore, the temperature of the phosphorus-containing water flowing through the composite phosphorus removal matrix layer is 20–35 °C.

[0025] When phosphorus-containing water flows through the composite phosphorus removal matrix layer, the water comes into contact with the surfaces and pores of the three particulate materials. The calcium-containing components in the waste aerated concrete particles participate in the fixation of phosphate ions, the ceramsite forms a particle support and provides an adhesion interface, and the zeolite participates in the migration and fixation of phosphorus through channels and ion exchange interfaces, thus retaining phosphorus in the composite phosphorus removal matrix layer.

[0026] The embodiments of the present invention have the following advantages due to the adoption of the above technical solutions: 1. This invention combines waste aerated concrete particles, ceramsite, and zeolite in a mass ratio of 3:1:1. It utilizes the calcium-containing components and pore structure of the waste aerated concrete to fix phosphorus, and supplements the particle skeleton and pore interface with ceramsite and zeolite, so that the composite matrix can meet the needs of phosphorus adsorption and particle filling.

[0027] Second, this invention crushes, screens, washes and dries waste aerated concrete to form particles with relatively stable particle size and water content, and mixes them with ceramsite and zeolite in a certain proportion, which facilitates the metering and preparation of composite matrix and the filling of artificial wetlands.

[0028] Third, this invention uses waste aerated concrete as the main component of the composite phosphorus removal matrix, which can be used for the treatment of phosphorus-containing water in constructed wetlands, while providing a way to utilize waste aerated concrete as a resource.

[0029] The above overview is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of the invention will become readily apparent from the accompanying drawings and the following detailed description. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 The experimental matrix diagram for this invention shows, from left to right, ceramsite, river sand, zeolite, gravel, and aerated concrete; Figure 2 For technology roadmap; Figure 3 This is the matrix BET diagram of the present invention; Figure 4 This is a graph showing the adsorption capacity of phosphorus on the same matrix according to the present invention; Figure 5 Isotherm curves of phosphorus for different matrices according to the present invention; Figure 6 This is a graph showing the adsorption capacity of phosphorus for different matrix combinations according to the present invention. Figure 7 This is a diagram showing the adsorption kinetics of phosphorus by GTF311 at different particle sizes according to the present invention. Figure 8 This is a graph showing the adsorption kinetics of phosphorus by GTF311 at different temperatures according to the present invention. Figure 9 This invention presents the adsorption kinetics of phosphorus by GFT311 under different influent concentrations. Detailed Implementation

[0032] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0033] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0034] like Figure 1 As shown, this embodiment of the invention provides a waste aerated concrete composite phosphorus removal wetland matrix and its preparation and application method. The composite phosphorus removal matrix includes waste aerated concrete particles, ceramsite, and zeolite. The three granular materials maintain their particle shape and are mixed with each other. The mass ratio of waste aerated concrete particles, ceramsite, and zeolite is 3:1:1.

[0035] Waste aerated concrete particles, as the main component of the composite phosphorus removal matrix, have a porous structure and contain components such as calcium, silicon, and aluminum, which can provide a reaction interface for the contact between phosphorus-containing water and the matrix and for phosphorus fixation. Ceramsite and zeolite are dispersed between the waste aerated concrete particles. Ceramsite forms particle support, while zeolite provides channels and ion exchange interfaces. The three particulate materials together constitute a composite matrix suitable for filling artificial wetland beds.

[0036] Unless otherwise stated, all proportions in this embodiment are mass ratios, and particle size refers to the range of sieve aperture sizes corresponding to the particles after sieving.

[0037] The matrix materials used in this embodiment include waste aerated concrete, ceramsite, zeolite, river sand, and gravel. Among them, river sand and gravel are used for comparative tests on the adsorption performance of a single matrix.

[0038] Waste aerated concrete can be obtained from block waste materials generated during the processing, construction, or demolition of aerated concrete blocks. First, the waste aerated concrete is crushed into particles, and then, according to the needs of the test or application, it is screened to obtain waste aerated concrete particles with particle sizes of 1-2 mm, 2-4 mm, and 4-8 mm.

[0039] Ceramsite, zeolite, river sand, and gravel were sieved into particles with a diameter of 2–4 mm.

[0040] The screened waste aerated concrete particles, ceramsite, zeolite, river sand, and gravel were thoroughly rinsed with tap water to remove dust and washable impurities from the particle surface, and then rinsed with distilled water. The rinsed matrix particles were placed in an electric heating blast drying oven and dried at 150 ℃ for 8 h. After being removed, they were naturally cooled to room temperature and sealed for storage.

[0041] In this embodiment, anhydrous potassium dihydrogen phosphate was used to prepare a phosphorus-containing standard solution; the initial pH of the test solution was adjusted using 0.1 mol / L hydrochloric acid solution and 0.1 mol / L sodium hydroxide solution; the total phosphorus concentration was determined by ammonium molybdate spectrophotometry, and the pH value was determined by glass electrode method.

[0042] Example 1 This embodiment prepares a composite phosphorus removal wetland matrix from waste aerated concrete, and the specific steps are as follows: S1. The waste aerated concrete particles with a particle size of 1-2 mm obtained after crushing and screening are thoroughly rinsed with tap water and then rinsed with distilled water; the ceramsite and zeolite with a particle size of 2-4 mm are cleaned in the same way.

[0043] S2. Place the cleaned waste aerated concrete particles, ceramsite and zeolite in an electric heating drying oven at 150 ℃ and dry for 8 h. Remove and cool to room temperature.

[0044] S3. Weigh 300 g of dried waste aerated concrete particles, 100 g of ceramsite and 100 g of zeolite, mix the three granular materials evenly to obtain a composite phosphorus removal matrix from waste aerated concrete.

[0045] In this embodiment, the mass ratio of waste aerated concrete particles, ceramsite, and zeolite is 3:1:1, the particle size of the waste aerated concrete particles is 1-2 mm, and the particle size of both ceramsite and zeolite is 2-4 mm.

[0046] Example 2 The difference between this embodiment and Embodiment 1 is that the particle size of the waste aerated concrete particles is 2 to 4 mm.

[0047] Specifically, 300 g of waste aerated concrete particles with a particle size of 2-4 mm, 100 g of ceramsite with a particle size of 2-4 mm, and 100 g of zeolite with a particle size of 2-4 mm were weighed; all three types of particles were sequentially washed with tap water, rinsed with distilled water, and dried at 150 ℃ for 8 hours, and then mixed to obtain a composite phosphorus removal matrix from waste aerated concrete.

[0048] Example 3 The difference between this embodiment and Embodiment 1 is that the particle size of the waste aerated concrete particles is 4 to 8 mm.

[0049] Specifically, 300 g of waste aerated concrete particles with a particle size of 4-8 mm, 100 g of ceramsite with a particle size of 2-4 mm, and 100 g of zeolite with a particle size of 2-4 mm were weighed out. All three types of particles were washed with tap water, rinsed with distilled water, and dried at 150 ℃ for 8 hours in sequence, and then mixed to obtain a composite phosphorus removal matrix for waste aerated concrete.

[0050] Application Example 1 The waste aerated concrete composite phosphorus removal wetland matrix prepared in Example 1 was filled into the artificial wetland bed to form a composite phosphorus removal matrix layer. During filling, the waste aerated concrete particles, ceramsite and zeolite were kept mixed and distributed to avoid obvious stratification of the three particle materials during the filling process.

[0051] Phosphorus-containing water is introduced from the inlet of the constructed wetland bed, flows through the composite phosphorus removal matrix layer and comes into contact with waste aerated concrete particles, ceramsite and zeolite, and is then discharged from the outlet of the constructed wetland bed.

[0052] The composite phosphorus removal matrix layer can be used as an independent phosphorus removal layer in the constructed wetland bed, or it can be set up in conjunction with other support layers or plant planting layers in the constructed wetland. The total phosphorus concentration of the phosphorus-containing water in the influent used in this application example can be 1 to 20 mg / L, and the operating temperature can be 20 to 35 ℃.

[0053] When phosphorus-containing water flows through the composite phosphorus removal matrix layer, the phosphate ions in the water come into contact with the surface and pores of the waste aerated concrete particles. The ceramsite and zeolite form particle support and pore interface in the composite matrix layer, thus providing conditions for the adsorption and fixation of phosphorus in the matrix layer.

[0054] This application example is used to illustrate the filling and watering application of the composite phosphorus removal substrate of the present invention in constructed wetlands, and does not limit the present invention to specific wetland bed dimensions, substrate layer thickness or hydraulic retention time.

[0055] Comparative Example 1 Ceramsite with a particle size of 2-4 mm was used as the single matrix; the ceramsite was successively washed with tap water, rinsed with distilled water, and dried at 150 ℃ for 8 h.

[0056] Comparative Example 2 Zeolite with a particle size of 2–4 mm was used as a single matrix; the zeolite was successively rinsed with tap water, rinsed with distilled water, and dried at 150 °C for 8 h.

[0057] Comparative Example 3 River sand with a particle size of 2–4 mm was used as the single matrix; the river sand was successively washed with tap water, rinsed with distilled water, and dried at 150 ℃ for 8 h.

[0058] Comparative Example 4 Gravel with a particle size of 2–4 mm was used as a single matrix; the gravel was successively washed with tap water, rinsed with distilled water, and dried at 150 ℃ for 8 h.

[0059] Comparative Example 5 Waste aerated concrete particles were used as the single matrix; the waste aerated concrete particles were sequentially washed with tap water, rinsed with distilled water, and dried at 150 ℃ for 8 hours.

[0060] Comparative Example 6 Waste aerated concrete particles, ceramsite, and zeolite were mixed in a mass ratio of 1:1:1, and the mixture was designated as GTF111.

[0061] Comparative Example 7 Waste aerated concrete particles, ceramsite, and zeolite were mixed in a mass ratio of 2:1:1, and the mixture was designated as GTF211.

[0062] Comparative Example 8 The ceramsite and zeolite are mixed in a 1:1 mass ratio, without adding waste aerated concrete particles, and this mixture is designated as GTF011.

[0063] Comparative Example 9 Waste aerated concrete particles, ceramsite, and zeolite were mixed in a mass ratio of 1:2:1 and denoted as GTF121.

[0064] Comparative Example 10 Waste aerated concrete particles, ceramsite, and zeolite were mixed in a mass ratio of 4:1:1, and the mixture was designated as GTF411.

[0065] Comparative Example 11 Waste aerated concrete particles, ceramsite, and zeolite were mixed in a mass ratio of 1:3:1 and denoted as GTF131.

[0066] In the above composite ratio, G, T, and F represent waste aerated concrete particles, ceramsite, and zeolite, respectively, and the numbers represent the mass fractions of the three particulate materials. The composite ratio corresponding to Example 1 is denoted as GTF311.

[0067] Test Example 1 Samples of expanded clay, zeolite, river sand, gravel, and waste aerated concrete particles were taken separately. The samples were dried and gold-sprayed. Scanning electron microscopy was used to observe the surface morphology, porosity, cracks, and particle packing characteristics of each matrix sample (e.g., ...). Figure 2 (As shown).

[0068] The observation results show that the surface of ceramsite is irregularly granular, with local holes, cracks and uneven structures; the surface of zeolite is formed by the accumulation of fine particles, with grooves and pores between the particles; the surface of river sand is relatively flat, with fewer observable pores and cracks; the surface of gravel has irregular edges and local microcracks; the surface of waste aerated concrete particles has obvious honeycomb pores, with abundant pore distribution and a certain degree of roughness in the pore walls.

[0069] The above microstructures illustrate the differences in particle surface and pore structure among different matrices. Microstructures are used to describe the contact interfaces that the matrix may provide and are not used as the sole basis for judging phosphorus adsorption capacity.

[0070] Test Example 2 Weigh 5.0000±0.0015 g of each of the single matrices from Comparative Examples 1 to 5, place them in Erlenmeyer flasks, and add 150 mL of potassium dihydrogen phosphate standard solution with initial phosphorus concentrations of 10 mg / L, 20 mg / L, 30 mg / L, 40 mg / L, 60 mg / L, 120 mg / L, 180 mg / L, 260 mg / L, and 360 mg / L, respectively.

[0071] The initial pH of the solution was adjusted to 7.0 ± 0.1 using 0.1 mol / L hydrochloric acid and 0.1 mol / L sodium hydroxide solution, and the solution was shaken at 25 ℃ and 150 r / min for 48 h. After the reaction was completed, the solution was filtered, and the equilibrium total phosphorus concentration in the filtrate was determined.

[0072] The equilibrium adsorption capacity is calculated using the following formula: ; In the formula, To determine the equilibrium adsorption capacity, the unit is mg / g; The initial phosphorus concentration of the solution is expressed in mg / L. This represents the phosphorus concentration in the solution at adsorption equilibrium, expressed in mg / L. The volume of the phosphorus solution is in liters (L). The value represents the mass of the matrix, expressed in grams (g).

[0073] Phosphorus removal rate is calculated using the following formula: ; In the formula, This represents the phosphorus removal rate.

[0074] The equilibrium concentrations after adsorption of each individual matrix are shown in Table 1.

[0075] Table 1. Equilibrium concentrations of a single matrix at different initial phosphorus concentrations. ; The equilibrium adsorption capacity of each individual matrix was calculated based on the equilibrium concentration in Table 1, and the results are shown in Table 2.

[0076] Table 2. Equilibrium adsorption capacity of a single matrix at different initial phosphorus concentrations ; Based on Table 2 Figure 3 It can be seen that, under the same initial phosphorus concentration, the adsorption capacity of the five single matrices is generally higher than that of waste aerated concrete, zeolite, gravel and river sand. When the initial phosphorus concentration is 360 mg / L, the measured equilibrium adsorption capacity of waste aerated concrete particles is 9.773 mg / g.

[0077] To further reveal the adsorption characteristics of phosphorus by the matrix, nonlinear fitting was performed on the phosphorus adsorption experimental data using Origin software. The Langmuir isotherm adsorption model and the Freundlich isotherm adsorption model were introduced for simulation analysis, such as... Figure 4 As shown.

[0078] Table 3 Fitting parameters for the single-matrix isothermal adsorption model ; Table 3 shows that the correlation coefficients of the Langmuir model fitting for all five matrices are higher than those of the corresponding Freundlich model fitting. The theoretical maximum Langmuir adsorption capacity q_m of waste aerated concrete particles is 10.656 mg / g, which is higher than that of the other four single matrices, indicating that waste aerated concrete can be used as the main phosphorus removal component in the composite phosphorus removal matrix.

[0079] Test Example 3 Composite matrix samples prepared in Example 1 and Comparative Examples 6-11 were taken respectively, with the same addition mass and solid-liquid ratio for each group of composite matrices. 150 mL of potassium dihydrogen phosphate solution with an initial phosphorus concentration of 30 mg / L was added to each group of composite matrices, and adsorption reactions were carried out under the same shaking conditions. Samples were taken at 1 h, 2 h, 4 h, 8 h, 12 h, 24 h, and 48 h of the reaction to determine the total phosphorus concentration in the solution and calculate the adsorption amount at each time point.

[0080] The measured equilibrium adsorption capacities of the seven composite ratios over 48 hours are ranked as follows: GTF311 > GTF411 > GTF211 > GTF111 > GTF121 > GTF131 > GTF011, such as Figure 5 As shown.

[0081] Among them, the measured equilibrium adsorption capacity of the GTF311 composite matrix corresponding to Example 1 was 0.897 mg / g, which was the highest among the seven composite ratios.

[0082] The adsorption kinetic data were fitted using a pseudo-first-order kinetic model, a pseudo-second-order kinetic model, and an Elovich model. The pseudo-first-order kinetic model could not yield a positive equilibrium adsorption amount with reasonable physical meaning and was therefore not used as the evaluation model.

[0083] use The Elovich model is fitted using the form, where, for Adsorption amount at any given time For the intercept parameter, The coefficients for the logarithmic time term are shown in Table 4.

[0084] Table 4 Fitting parameters of the Elovich kinetic model for the composite matrix ; The fitting results of the quasi-second-order dynamic model are shown in Table 5.

[0085] Table 5 Fitting parameters of the quasi-second-order kinetic model of the composite matrix ; As shown in Table 5, the correlation coefficient of the pseudo-second-order kinetic model fitting for each composite matrix is ​​0.999, and the relative deviation between the theoretical equilibrium adsorption amount and the measured equilibrium adsorption amount is less than 1%. This result indicates that the phosphorus adsorption process of the composite matrix is ​​in good agreement with the pseudo-second-order kinetic model, and shows that the adsorption and immobilization of surface active sites have an impact on the process.

[0086] In GTF011, the absence of waste aerated concrete particles resulted in the lowest measured equilibrium adsorption capacity. As the proportion of waste aerated concrete particles increased, the overall equilibrium adsorption capacity of the composite matrix increased. When the mass ratio of waste aerated concrete particles, ceramsite, and zeolite reached 3:1:1, further increasing the proportion of waste aerated concrete particles to 4:1:1 did not lead to a further increase in the measured equilibrium adsorption capacity. Therefore, among the seven ratios set in this experiment, 3:1:1 resulted in the highest adsorption capacity.

[0087] Test Example 4 The composite phosphorus removal matrix prepared in Examples 1, 2 and 3 were used to conduct particle size effect tests. The initial phosphorus concentration of the influent was controlled at 10 mg / L and the reaction temperature was 25 °C. All other shaking conditions were the same. After 12 h of reaction, the equilibrium phosphorus concentration in the solution was measured, and the adsorption amount and removal rate were calculated.

[0088] The test results are shown in Table 6.

[0089] Table 6 Adsorption results for different particle sizes of waste aerated concrete. ; From Table 6 and Figure 6It can be seen that, under the test conditions, the composite matrix using waste aerated concrete particles with a particle size of 1-2 mm has a high adsorption capacity and removal rate. As the particle size of waste aerated concrete particles increases, the adsorption capacity and removal rate of the composite matrix show a decreasing trend.

[0090] Reducing particle size increases the surface area of ​​waste aerated concrete particles in contact with water per unit mass and shortens the diffusion path of phosphate into the pores inside the particles. Therefore, under static test conditions without considering changes in the hydraulic parameters of the constructed wetland bed, waste aerated concrete particles with a particle size of 1–2 mm are more conducive to phosphorus adsorption and fixation.

[0091] The above results only reflect the differences in static adsorption under different particle size conditions and are not intended to directly illustrate the anti-clogging performance or long-term hydraulic performance of constructed wetland substrate layers with different particle sizes.

[0092] Test Example 5 Using the composite phosphorus removal matrix prepared in Example 1, with an initial phosphorus concentration of 10 mg / L in the influent and a particle size of 1–2 mm from the waste aerated concrete, adsorption experiments were conducted at 20 ℃, 25 ℃, 30 ℃, and 35 ℃. The equilibrium phosphorus concentration was measured after 12 h of reaction for each group, and the adsorption capacity and removal rate were calculated.

[0093] The test results are shown in Table 7.

[0094] Table 7 Adsorption results of composite phosphorus removal matrix at different temperatures ; From Table 7 and Figure 7 It can be seen that, within the range of 20–35 °C, as the reaction temperature increases, the adsorption capacity and removal rate of the composite phosphorus removal matrix generally increase within a 12-hour reaction time.

[0095] Increased temperature enhances the migration of phosphate ions in the liquid phase and increases the chances of phosphate ions contacting active sites on the matrix surface and within the pores; therefore, under the conditions of this experiment, a higher temperature is beneficial for the adsorption process to proceed within the set reaction time.

[0096] Test Example 6 Using the composite phosphorus removal matrix prepared in Example 1, and controlling the particle size of waste aerated concrete particles to be 1–2 mm and the reaction temperature to be 25 °C, phosphorus-containing solutions with initial phosphorus concentrations of 1 mg / L, 10 mg / L, 20 mg / L, and 60 mg / L were prepared. After reacting for 12 h under the same shaking conditions, the equilibrium phosphorus concentration was measured, and the adsorption capacity and removal rate were calculated.

[0097] The test results are shown in Table 8.

[0098] Table 8 Adsorption results of the composite phosphorus removal matrix under different initial phosphorus concentrations ; From Table 8 and Figure 8 It can be seen that the adsorption capacity of the composite phosphorus removal matrix per unit mass increases with the increase of the initial phosphorus concentration; when the initial phosphorus concentration is 1-20 mg / L, the phosphorus removal rate of each group remains above 88%; when the initial phosphorus concentration is increased to 60 mg / L, the adsorption capacity continues to increase, but the removal rate decreases to 71.483%. Increasing the initial phosphorus concentration will increase the concentration difference between the liquid phase and the matrix surface, causing more phosphorus to migrate to the matrix surface; however, the composite phosphorus removal matrix can only provide a limited number of adsorption and reaction sites. When the phosphorus concentration in the influent increases further, some sites are gradually occupied, leading to a decrease in the removal rate. Based on the above test results, waste aerated concrete showed a higher phosphorus adsorption capacity among the five single matrices. Its measured equilibrium adsorption capacity and Langmuir theoretical maximum adsorption capacity were both higher than those of ceramsite, zeolite, river sand and gravel, indicating that waste aerated concrete is suitable as the main component material in composite phosphorus removal matrices. Among the seven composite ratios composed of waste aerated concrete particles, ceramsite, and zeolite, the 3:1:1 ratio showed the highest measured equilibrium adsorption capacity. This ratio maintains a high content of waste aerated concrete particles in the composite matrix while retaining the role of ceramsite and zeolite in forming particle support and pore interface. The particle size effect test shows that, under static adsorption conditions, reducing the particle size of waste aerated concrete particles is beneficial to increasing the contact area between the composite matrix and phosphorus-containing water and the phosphorus removal rate. The temperature and influent concentration test further shows that the composite phosphorus removal matrix of the present invention can adsorb and fix phosphorus in water within the range of 20-35 ℃ and initial influent phosphorus concentration of 1-20 mg / L. This invention granulates, cleans, and dries waste aerated concrete, then mixes it with ceramsite and zeolite in a 3:1:1 mass ratio to form a composite phosphorus removal matrix with a clear composition that is easy to measure and fill. This composite phosphorus removal matrix can be filled into artificial wetland beds, allowing phosphorus-containing water to flow through the composite phosphorus removal matrix layer for treatment, and provides an implementation method for the resource utilization of waste aerated concrete.

[0099] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various variations or substitutions within the technical scope disclosed in the present invention, and these should all be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A composite phosphorus removal wetland substrate made from waste aerated concrete, characterized in that, It includes waste aerated concrete particles, ceramsite, and zeolite, wherein the waste aerated concrete particles, ceramsite, and zeolite are maintained in particle form and mixed together, and the mass ratio of the waste aerated concrete particles, ceramsite, and zeolite is 3:1:

1.

2. The waste aerated concrete composite phosphorus removal wetland substrate according to claim 1, characterized in that, The waste aerated concrete particles are obtained by crushing and screening waste aerated concrete materials.

3. The waste aerated concrete composite phosphorus removal wetland substrate according to claim 1, characterized in that, The particle size of the waste aerated concrete particles is 1-8 mm, and the particle size of the ceramsite and the zeolite are both 2-4 mm.

4. The waste aerated concrete composite phosphorus removal wetland substrate according to claim 3, characterized in that, The particle size of the waste aerated concrete particles is 1-2 mm; the waste aerated concrete particles, the ceramsite and the zeolite are all particles that have been successively washed with tap water, rinsed with distilled water and dried at 150 ℃ for 8 h.

5. A method for preparing a composite phosphorus removal wetland substrate made from waste aerated concrete, characterized in that, Includes the following steps: S1. The waste aerated concrete material is crushed and screened to obtain waste aerated concrete particles, and the ceramsite and zeolite are screened separately. S2. Clean the waste aerated concrete particles, the ceramsite, and the zeolite respectively; S3. Dry the cleaned waste aerated concrete particles, the ceramsite, and the zeolite respectively; S4. The dried waste aerated concrete particles, the ceramsite, and the zeolite are mixed in a mass ratio of 3:1:1 to obtain a waste aerated concrete composite phosphorus removal wetland matrix.

6. The method for preparing the waste aerated concrete composite phosphorus removal wetland substrate according to claim 5, characterized in that, In step S1, the waste aerated concrete material is crushed and screened into waste aerated concrete particles with a particle size of 1 to 8 mm, and the ceramsite and the zeolite are screened into particles with a particle size of 2 to 4 mm.

7. The method for preparing waste aerated concrete composite phosphorus removal wetland substrate according to claim 5, characterized in that, In step S2, the waste aerated concrete particles, the ceramsite, and the zeolite are first rinsed with tap water, and then rinsed with distilled water. In step S3, the rinsed waste aerated concrete particles, ceramsite, and zeolite are dried at 150 °C for 8 h.

8. A method for applying a waste aerated concrete composite phosphorus removal wetland substrate, characterized in that, Includes the following steps: A1. Waste aerated concrete particles, ceramsite and zeolite are mixed in a mass ratio of 3:1:1 to obtain a composite phosphorus removal matrix, and the composite phosphorus removal matrix is ​​filled into the artificial wetland bed to form a composite phosphorus removal matrix layer. A2. Phosphorus-containing water is introduced into the constructed wetland bed, so that the phosphorus-containing water flows through the composite phosphorus removal wetland matrix layer and comes into contact with the waste aerated concrete particles, the ceramsite and the zeolite; A3. Discharge the water that has flowed through the composite phosphorus removal wetland matrix layer from the constructed wetland bed.

9. The application method of the waste aerated concrete composite phosphorus removal wetland substrate according to claim 8, characterized in that, The total phosphorus concentration of the phosphorus-containing water entering the constructed wetland bed is 1–20 mg / L.

10. The application method of the waste aerated concrete composite phosphorus removal wetland substrate according to claim 8, characterized in that, The particle size of the waste aerated concrete particles is 1-2 mm, the particle size of the ceramsite and the zeolite are both 2-4 mm, and the temperature of the phosphorus-containing water flowing through the composite phosphorus removal wetland matrix layer is 20-35 ℃.

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