Modified glass pumice, preparation method and application

Abstract

The invention provides a modified glass pumice stone, a preparation method and application, the modified glass pumice stone is prepared through zeolite loading and magnesium-iron composite metal oxide coating, and the modified glass pumice stone comprises the following components in percentage by mass: 71.4-74.1% of a glass pumice stone matrix, 14.3-14.8% of zeolite and 11.1-14.3% of magnesium-iron oxide; modified glass pumice stones are applied to a planting roof rainwater direct recycling system, a planting roof adopts a two-stage series structure and is separated by a retaining wall, the first stage is filled with common glass pumice stones, and the second stage is filled with the modified glass pumice stones; the floor comprises a floor layer, a leveling layer, an SBS waterproof layer, a root puncture resistant layer, a modified planting layer and plants from bottom to top. While roof rainwater collection is achieved, the collected rainwater is purified to meet the rainwater recycling standard and then collected to the ground through the building rainwater downpipe to be directly recycled, lifting and pressurization are avoided, and direct recycling of the rainwater is achieved in an economical, energy-saving and land-saving mode while the environment is beautified by planting the roof.

Description

Technical Field

[0001] This invention relates to the field of rainwater resource utilization technology, specifically to a modified glass pumice, its preparation method, and its application. Background Technology

[0002] With rapid urbanization, the increase in impervious surfaces in cities has significantly impacted the infiltration conditions of rainwater runoff. Large amounts of rainwater runoff are discharged through urban rivers and stormwater pipes, leading to significant changes in the urban hydrological cycle. This, in turn, increases the risk of flooding for urban drainage systems and flood control projects, as well as the corresponding management costs. Furthermore, this change also results in the waste of rainwater resources. Therefore, implementing rainwater resource utilization in buildings and residential communities is an effective strategy for solving these problems and a key direction for future comprehensive urban water resource management.

[0003] In recent years, rooftop greening technology has become increasingly popular, with rooftop designs for new buildings and renovations of existing ones frequently adopting greening solutions. This technology has played a significant role in energy conservation, emission reduction, and ecological improvement. However, traditional rooftop greening uses planting soil that is heavy, prone to compaction, and has insufficient water retention, requiring frequent irrigation, especially during dry seasons, to maintain vegetation growth. Glass pumice (GP) is a porous, lightweight inorganic material made from waste glass, ground into powder and mixed with specific additives, then produced through a high-temperature foaming process. It is named for its porous structure and lightweight properties, derived from waste glass. Chemically, glass pumice is a synthetic silicate material whose pore size and particle size can be adjusted during production. Due to its porous and lightweight nature, excellent porosity, good biomass carrying capacity, superior water retention, and low biotoxicity, glass pumice has been widely used in landscaping, water treatment, construction engineering, and soil improvement.

[0004] The water treatment efficiency of glass pumice mainly relies on its porous structure and strong biological carrying capacity, which provides favorable conditions for the formation of biofilms by water-treatment microorganisms, thus facilitating water purification through microbial action. However, as it is a synthetic silicate material, its other water treatment functions are relatively weak. It struggles to meet rainwater reuse standards for indicators such as total nitrogen in stormwater runoff pollution treatment, requiring further enhancement and optimization. Currently, glass pumice is used for applications such as roof drainage and lawn planting. For example, the invention patent application number 202311343251.5 proposes a pyrite-modified glass pumice denitrification and phosphorus removal material, its preparation method, and its application. The effluent total nitrogen concentration is <5 mg / L, with a removal rate of over 65%; the effluent total phosphorus concentration is <0.2 mg / L, with a removal rate of over 60%. However, the performance of glass pumice modified solely with pyrite still has room for improvement, as its nitrogen and phosphorus pollutant removal rate is lower than that of the modification method described in this proposal. The utility model patent with application number 201721074617.3 uses glass pumice in a roof drainage diversion system; the utility model patents with application numbers 201920676687.9 and 201920676664.8 use glass pumice for roof and balcony lawn planting. However, the above-mentioned similar patents mainly utilize the characteristics of glass pumice being lightweight and having good water retention for greening and planting, without considering its water purification effect or making targeted optimizations and improvements to achieve the treatment of rainwater runoff pollution and direct reuse.

[0005] The idea behind this invention is to further functionalize and modify glass pumice, and then apply it to rooftop greening planting substrates. While leveraging its advantages such as light weight and strong water retention capacity, this invention enhances its ability to remove nitrogen and phosphorus pollutants from rainwater runoff, enabling rooftop rainwater to be purified through glass pumice substrate planting and then directly reused on-site. This invention has promising application prospects. Summary of the Invention

[0006] Purpose of the invention: The purpose of this invention is to address the shortcomings of existing technologies by providing a modified glass pumice, its preparation method, and its application. By further modifying the glass pumice to enhance its rainwater runoff pollution treatment efficiency, a rainwater purification and recycling system for green roofs based on modified glass pumice is constructed. While collecting rainwater from the roof, the collected rainwater is purified to meet rainwater reuse standards and then collected to the ground for direct reuse through building rainwater downpipes, avoiding the need for lifting and pressurization. This achieves direct rainwater reuse in an economical, energy-saving, and land-saving manner while beautifying the environment with green roofs.

[0007] Technical solution: The modified glass pumice of the present invention comprises the following components: glass pumice matrix, artificial zeolite loaded on the surface and pores of the matrix, and magnesium-iron composite metal oxide coated on the artificial zeolite and the surface of the glass pumice matrix.

[0008] Furthermore, the mass fractions of each component in the modified glass pumice are as follows: glass pumice matrix: 71.4%–74.1%, artificial zeolite: 14.3%–14.8%, and magnesium-iron composite metal oxide: 11.1%–14.3%.

[0009] A method for preparing the modified glass pumice as described above includes the following steps:

[0010] Step 1: Take 2g of 200-mesh artificial zeolite and put it in 500mL of water. Place it on a magnetic stirrer and stir to disperse the artificial zeolite into a suspension. Add 10g of glass pumice to the suspension and place it on a constant temperature water bath shaker at 25℃ and 100.0r / min for 2h. After filtering to separate the glass pumice, transfer it to an oven and dry it at 105℃ for 2h to obtain glass pumice loaded with zeolite.

[0011] Step 2: Prepare 500 mL of 2.0 mol / L MgCl2 solution and 500 mL of 0.2 mol / L FeCl3 solution respectively. Mix the two solutions and adjust the pH of the solution to 6.0; to obtain a mixed solution.

[0012] Step 3: Take 10g of glass pumice with zeolite load prepared in Step 1, add it to 1L of mixed solution prepared in Step 2, place it in a constant temperature water bath shaker, shake it for 24h at 25℃ and 100.0r / min, and filter to separate the glass pumice.

[0013] Step 4: Place the separated glass pumice in an oven at 105℃ and dry for 8 hours. Then transfer it to a muffle furnace and calcine it at 500℃ for 3 hours under nitrogen protection and oxygen-free environment. After taking it out, you will get a glass pumice composite material loaded with zeolite-composite metal oxide.

[0014] An application of the modified glass pumice prepared as described above in a water treatment system.

[0015] Furthermore, the water bodies in the water treatment system include rainwater, sewage, and seawater.

[0016] A direct rainwater recycling system for green roofs based on the modified glass pumice prepared above is disclosed. The system includes a green roof and a recycling device on one side. A roof layer is provided on one side of the green roof, and a recycling device is provided on the other side. The green roof is divided into a first-level green roof and a second-level green roof by a retaining wall. Rainwater collected in the roof layer enters the first-level green roof through an inlet pipe. After purification, the runoff enters the second-level green roof through a connecting pipe for secondary purification. After secondary purification, the runoff flows by gravity through the recycling device to a ground-level clear water pool.

[0017] Furthermore, the first and second levels of the green roof, from bottom to top, consist of a floor slab load-bearing layer, a leveling layer, an SBS waterproofing layer, a root-penetration resistant isolation layer, a modified glass pumice planting layer, and plants. The modified glass pumice planting layer is made of modified glass pumice, with a thickness of 200-400mm and a particle size of 10-30mm. The floor slab load-bearing structure is a cast-in-place reinforced concrete roof slab, the thickness of which is determined according to the architectural design. The leveling layer is a 20mm thick mortar, and its flatness should meet the construction requirements of the waterproof membrane. The SBS waterproofing layer consists of two layers of SBS waterproof membrane, with overlaps conforming to the construction requirements of waterproof membranes. The root-penetration resistant isolation layer is a 4-6mm thick polyvinyl chloride plastic film isolation layer. The membrane construction should meet the requirements for polymer waterproof membrane construction; the overlap width of the long and short sides should be greater than 100mm, and the overlap joints should be sealed with compatible sealant.

[0018] Furthermore, the recycling device includes an inlet pipe installed below the retaining wall of the first-level green roof. The inlet pipe is connected to a drain pipe installed below the retaining wall of the second-level green roof via a connecting pipe. The outlet of the drain pipe is connected to a collection trough. The collection trough is located between the retaining wall and the outer wall of the second-level green roof. A rainwater hopper is installed below the collection trough. The rainwater hopper is connected to a ground clear water pool via a rainwater downpipe.

[0019] Furthermore, the collection trough is filled with glass pumice of different particle sizes in layers. The lower layer is filled with glass pumice of 10-15mm in particle size, and the upper layer is filled with gravel of 15-25mm in particle size. The collection trough collects rainwater runoff after the green roof is treated. The collection trough is filled with glass pumice of different particle sizes in layers. The lower layer is filled with glass pumice of 10-15mm in particle size, and the upper layer is filled with gravel of 15-25mm in particle size to cover it and prevent the glass pumice from being washed away by rainwater runoff due to its light weight.

[0020] Beneficial effects: Compared with the prior art, the advantages of the present invention are as follows:

[0021] (1) Compared with traditional planting soil for green roofs, this invention makes full use of the lightweight, water-holding and water-preserving, stable and biological load-bearing capacity of glass pumice substrate. Applying it to green roofs can reduce the load on the roof structure. At the same time, its good water-holding capacity is conducive to plant growth and reduces maintenance requirements. In addition, by utilizing the characteristics of strong biological load-bearing capacity, the loaded microorganisms enhance its efficiency in removing pollutants from rainwater runoff. The two-stage green roof structure design enhances the contact time between rainwater runoff and substrate, and improves the water purification effect.

[0022] (2) Further investigation into NO3 in rainwater runoff from glass-cemented pumice substrate green roofs - -N and PO4 3-The removal rate of nitrogen and phosphorus in rainwater runoff is limited, and the effluent concentration fails to meet the standards for rainwater reuse. The core of this invention is to functionalize pumice by loading zeolite to enhance the adsorption and removal of ammonia nitrogen. The ammonia nitrogen adsorbed during rainfall can be absorbed and utilized by rooftop plants during the intervals between rainfall, thus freeing up adsorption capacity for the next rainfall period. Furthermore, loading magnesium and iron composite metal oxides enhances its nitrogen and phosphorus removal efficiency in rainwater runoff, enabling the effluent to meet the standards for rainwater reuse.

[0023] (3) This invention enhances the purification efficiency of rainwater runoff from green roofs, enabling direct utilization of rainwater and providing a direct rainwater utilization pathway for buildings and communities. Compared with existing practices of setting up rainwater storage tanks and rainwater pump rooms for treatment and reuse, this invention utilizes the green roof itself to purify rainwater, reducing land occupation and system costs. In addition, by using existing rainwater downpipes and gravity to collect the purified rainwater and drop it to the ground, the energy consumption of traditional rainwater lifting methods can be reduced. The entire system can purify and utilize rainwater without energy consumption, achieving direct rainwater reuse in an economical, energy-saving, and land-saving manner while beautifying the environment with green roofs. Attached Figure Description

[0024] Figure 1 Schematic diagram of a direct rainwater recycling system for modified glass lightweight stone planted roofs;

[0025] In the diagram: 1-Floor load-bearing structural layer; 2-Roof layer; 3-Water inlet pipe; 4-Partition wall; 5-Leveling layer; 6-SBS waterproof layer; 7-Root penetration resistant isolation layer; 8-Modified glass lightweight stone planting layer; 9 Connecting pipe; 10-Drainage pipe; 11-Rainwater hopper; 12-Downpipe; 13-Collection trough; 14-Plants.

[0026] Figure 2 SEM images of glass pumice before and after modification: GP (left) FMGP (right);

[0027] Figure 3 XRD patterns (left) and phase analysis (right) of glassy pumice before and after modification;

[0028] Figure 4 Comparison of the removal efficiencies of glass pumice, zeolite-modified glass pumice, and zeolite-composite metal oxide-modified glass zeolite for NH4+-N and PO4-, respectively.

[0029] Figure 5 Fitting curves of pollutant removal kinetics from zeolite-composite metal oxide modified glass pumice (FMGP);

[0030] Figure 6 The modified glass lightweight stone green roof rainwater direct reuse system demonstrates the effectiveness of removing pollutants from actual rainfall runoff. Detailed Implementation

[0031] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings, but the scope of protection of the present invention is not limited to the embodiments described.

[0032] Example 1: Modified Glass Pumice and its Preparation Method

[0033] A modified glass pumice comprises the following components: a glass pumice matrix, artificial zeolite supported on the surface and within the pores of the matrix, and a magnesium-iron composite metal oxide coating the artificial zeolite and the surface of the glass pumice matrix. The mass percentages of each component in the modified glass pumice are: glass pumice matrix: 71.4%–74.1%, artificial zeolite: 14.3%–14.8%, and magnesium-iron composite metal oxide: 11.1%–14.3%.

[0034] A method for preparing the modified glass pumice as described above includes the following steps:

[0035] Step 1: Take 2g of 200-mesh artificial zeolite and put it in 500mL of water. Place it on a magnetic stirrer and stir to disperse the artificial zeolite into a suspension. Add 10g of glass pumice to the suspension and place it on a constant temperature water bath shaker at 25℃ and 100.0r / min for 2h. After filtering to separate the glass pumice, transfer it to an oven and dry it at 105℃ for 2h to obtain glass pumice loaded with zeolite.

[0036] Step 2: Prepare 500 mL of 2.0 mol / L MgCl2 solution and 500 mL of 0.2 mol / L FeCl3 solution respectively. Mix the two solutions and adjust the pH of the solution to 6.0; to obtain a mixed solution.

[0037] Step 3: Take 10g of glass pumice with zeolite load prepared in Step 1, add it to 1L of mixed solution prepared in Step 2, place it in a constant temperature water bath shaker, shake it for 24h at 25℃ and 100.0r / min, and filter to separate the glass pumice.

[0038] Step 4: Place the separated glass pumice in an oven at 105℃ and dry for 8 hours. Then transfer it to a muffle furnace and calcine it at 500℃ for 3 hours under nitrogen protection and oxygen-free environment. After taking it out, you will get a glass pumice composite material loaded with zeolite-composite metal oxide.

[0039] Experimental Example 1: Performance Testing of Modified Glass Pumice

[0040] The surface morphology and structure of glass pumice before and after modification were analyzed by scanning electron microscopy (SEM). The changes in surface morphology and structure of glass pumice before and after modification were compared. The results are shown in [Figure 1]. Figure 2SEM images show that the internal pores of the magnesium / iron modified glass pumice expand and gradually break down, and abundant crystals are added to the surface, resulting in an irregular internal structure of the glass pumice.

[0041] X-ray diffraction analysis can be used to investigate the phase changes of glass pumice before and after modification. X-ray diffraction analysis was performed on dried and pretreated glass pumice samples within the 2θ range of 5–90°. The corresponding phases were analyzed using a standard comparison card. The results are shown in [Figure number missing]. Figure 3 GP contains a relatively simple phase composition, while FMGP has a more diverse phase composition. Clearly, the proportion of metal elements in FMGP is significantly higher, with the phases mainly existing as metal oxides. It is rich in MgO and Fe2O3, and substances such as Mg(OH)2, MgCl2, Fe(OH)3, and FeCl3 were also detected. This indicates that FMGP has a large number of metal cations on its surface, and free Mg in the solution... 2+ Can and NH4 + PO4 3- The reaction produces struvite precipitate (MgNH4PO4), which can improve the removal efficiency of nitrogen and phosphorus in rainwater runoff.

[0042] FMGP, with the addition of Fe and a decrease in Si content, exhibits a larger specific surface area, approximately 50% larger than GP. SEM reveals a collapse of the pore structure, with abundant new crystals on the surface, making the glass pumice's pore structure increasingly irregular. XRD results show that FMGP contains a richer variety of phases, including MgO, Fe2O3, Mg(OH)2, and Fe(OH)3, indicating that the modified glass pumice is alkaline, which favors PO4. 3- and NH4 + Adsorption.

[0043] Experimental Example 2: Comparative Test of Pollutant Removal Efficiency of Modified Glass Pumice

[0044] Three materials, namely glass pumice, zeolite-modified glass pumice, and zeolite-composite metal oxide glass pumice, were used to test their effects on...

[0045] NO3 was prepared using NH4Cl and KH2PO4 reagents. - -N concentration was 5.0 mg / L and PO4 -For a 1.5 mg / L solution, three 50 mL aliquots were added to separate 200 mL stoppered conical flasks. The pH was adjusted to 7.0. 0.2 g of each of the following solutions (optimal conditions: glass pumice, zeolite-modified glass pumice, and zeolite-composite metal oxide glass pumice) were weighed and placed in stoppered conical flasks, thoroughly shaken, and placed in a constant-temperature shaker at 25°C and a shaking speed of 200 r / min. Samples were taken at time points of 0.5 h, 1.0 h, 1.5 h, 2.0 h, 3.0 h, 6.0 h, 12.0 h, 16.0 h, and 24.0 h. The samples were filtered through a 0.45 μm microporous membrane, and the NH4+ content in the filtrate was determined. + -N and PO4 - Remaining concentration, comparing the pollutant removal effects of the three materials.

[0046] The experimental results are shown in Figure 4 It can be seen that pumice mainly removes pollutants through the action of loaded microorganisms over a relatively long period of time. Before modification, pumice was less effective at removing NH4. + -N and PO4 - The removal of NH4+ is relatively limited within a finite time. However, by using supported zeolites, its removal capacity for NH4+ can be significantly improved. + -N removal effect, and further loading of iron and magnesium composite metal oxides enhances its PO4 removal effect. - Removal efficiency. Zeolite-modified glass pumice (FMGP) compared to unmodified glass pumice has lower NH4 removal efficiency. + -N and PO4 - The removal efficiency is significantly enhanced.

[0047] Experimental Example 3: Phosphoretics of Pollutant Removal from Zeolite-Composite Metal Oxide Modified Glass Pumice (FMGP)

[0048] Weigh 0.2 g of the modified glass pumice FMGP under optimal conditions and place it in a stoppered conical flask. Shake thoroughly and place the flask in a constant-temperature shaker at 25°C with a shaking speed of 200 r / min. Take samples at time points of 0.5 h, 1.0 h, 1.5 h, 2.0 h, 3.0 h, 6.0 h, 12.0 h, 16.0 h, and 24.0 h. Filter the samples through a 0.45 μm microporous membrane and determine the NO3 content in the filtrate. - The remaining concentration of -N was determined, and the data were fitted using pseudo-first-order and pseudo-second-order kinetic models to investigate its effect on NO3-. - The principle of removing -N.

[0049] The test results are shown in Figure 5 NO3 -The adsorption capacity of -N on FMGP varies with adsorption time. With increasing adsorption time, the adsorption capacity increases rapidly before reaching equilibrium. FMGP for NO3... - The equilibrium adsorption capacity of -N is 0.139 mg·g. -1 NO3 via FMGP - The adsorption kinetic parameters fitted by the adsorption data of -N show that the adsorption kinetic data of FMGP are more consistent with the pseudo-second-order kinetic model, similar to MGP, with a correlation coefficient of 0.9655. When FMGP is used to adsorb NO3... - The adsorption capacity of -N at adsorption equilibrium is 0.137 mg·g. -1 The actual equilibrium adsorption capacity was 0.139 mg·g. -1 similar.

[0050] Example 2: A Direct Rainwater Recycling System for Green Roofs Based on Modified Glass Pumice

[0051] A direct rainwater recycling system for green roofs based on the modified glass pumice prepared above is disclosed. The system includes a green roof and a recycling device on one side. A roof layer 2 is provided on one side of the green roof, and a recycling device is provided on the other side. The green roof is divided into a first-level green roof and a second-level green roof by a retaining wall 4. Rainwater collected in the roof layer 2 enters the first-level green roof through an inlet pipe 3. After purification, the runoff enters the second-level green roof through a connecting pipe 9 for secondary purification. After secondary purification, the runoff flows by gravity through the recycling device to a ground-level clear water pool.

[0052] To meet the requirements for rainwater purification, a two-tiered green roof structure with interconnected retaining walls is used to increase the contact time between rainwater runoff and the substrate, thereby enhancing the rainwater purification effect. The first and second tiers of the green roof, from bottom to top, consist of a floor slab load-bearing layer 1, a leveling layer 5, an SBS waterproofing layer 6, a root-penetration-resistant isolation layer 7, a modified glass lightweight stone planting layer 8, and plants 14. The modified glass lightweight stone planting layer 8 is composed of modified glass lightweight stone, with a thickness of 200-400mm and a particle size of 10-30mm. The floor slab load-bearing structure layer 1 is a cast-in-place reinforced concrete roof slab, the thickness of which is determined according to the architectural design. The leveling layer 5 is a 20mm thick mortar, and its flatness should meet the construction requirements of the waterproof membrane. The SBS waterproofing layer 6 consists of two layers of SBS waterproof membrane, with overlaps conforming to the waterproof membrane construction requirements. The root-penetration resistant isolation layer 7 is a 4-6mm thick polyvinyl chloride plastic film isolation layer. The overlap width of the long and short sides should be greater than 100mm, and the overlap joints should be sealed with a compatible sealant. The roll material construction should meet the requirements for polymer waterproof roll material construction. The overlap width of the long and short sides should be greater than 100mm, and the overlap joints should be sealed with a compatible sealant. The recycling device includes a water inlet pipe 3 located below the retaining wall of the first-level green roof. The water inlet pipe 3 is connected to the drain pipe 10 located below the retaining wall of the second-level green roof through a connecting pipe 9. The outlet of the drain pipe 10 is connected to the collection trough 13. The collection trough 13 is located between the retaining wall and the outer wall of the second-level green roof. A rainwater hopper 11 is installed below the collection trough 13. The rainwater hopper 11 is connected to the ground clear water pool through a rainwater downpipe 12. The collection trough 13 is filled with layers of glass pumice of different sizes. The lower layer contains glass pumice with a size of 10-15mm, and the upper layer contains gravel with a size of 15-25mm. The collection trough 13 collects rainwater runoff from the green roof after treatment. The layered glass pumice filling in the collection trough 13 prevents the glass pumice from being washed away by rainwater runoff due to its light weight. The inlet pipe 3, connecting pipe 9, and drain pipe 10 in the recycling device are made of PVC-U pipes, with a diameter of 50-100mm depending on the area of ​​the green roof. The specifications of the rainwater hopper and downpipe are also calculated and determined based on the area of ​​the green roof they are responsible for.

[0053] like Figure 1 As shown, a modified glass lightweight stone green roof rainwater recycling system was constructed on the roof of the office building. It consists of two units (4m x 2m) forming a two-stage modified glass lightweight stone green roof unit, with a total area of ​​16m². 2The modified glass lightweight stone green roof structure, from bottom to top, consists of: a 200mm floor slab load-bearing layer; a surface layer that has been cleaned and leveled with 1-2cm of cement mortar; after the cement mortar has solidified, two layers of SBS waterproof membrane are applied; then a 4mm thick PVC plastic film is laid as a root-penetration resistant isolation layer, with an overlap width greater than 100mm on both the long and short sides, and the overlap joints are sealed with a compatible sealant. On the completed root-penetration resistant isolation layer, 300mm of glass lightweight stone with a particle size of 15-20cm is filled. The first-level green roof unit is filled with unmodified glass lightweight stone, while the second-level green roof unit is filled with modified glass lightweight stone prepared in batches according to the modified preparation method of this patented invention to enhance the efficiency of rainwater runoff pollution treatment. The surface planting consists of Crassulaceae seedlings and some canna lilies.

[0054] Rainfall collected on the roof surface is gathered through linear drainage ditches and enters the first-stage green roof unit through a De75mm PVC-U pipe. After treatment, it enters the second-stage green roof unit through a De75mm PVC-U connecting pipe to enhance the treatment efficiency of rainwater runoff pollution. The outlet of the second-stage green roof unit is a De110mm PVC-U drainage pipe that discharges to the original roof eaves gutter and rainwater hopper. Water quality samples are taken before the inlet of the first-stage green roof unit, at the inlet of the two-stage connecting pipe, and at the outlet of the second-stage green roof unit for water quality testing to evaluate its effectiveness in treating rainwater runoff pollution.

[0055] The modified glass lightweight stone green roof rainwater direct reuse system of Example 2 was used to conduct simulated rainfall runoff and actual rainfall treatment efficiency tests.

[0056] Experiment Example 4: Simulated Rainfall Runoff Pollution Treatment Efficiency Test

[0057] The influent water quality was determined by referencing the concentrations of major pollutants in urban road runoff. In the experiment, the proportions of anhydrous glucose, ammonium chloride, potassium nitrate, and potassium dihydrogen phosphate were controlled to simulate the major pollutants in road runoff. The pollutant concentrations in runoff varied across different underlying surfaces and regions, exhibiting an initial scouring effect and being related to the length of the pre-rainfall drought period; a longer drought period resulted in higher pollutant concentrations in the runoff. Therefore, considering all factors, three different influent pollution loads were identified. Details of the different influent pollution loads are shown in Table 1.

[0058] Table 1. Water quality characteristics of artificially simulated rainfall

[0059]

[0060] By comparing the effects of two sets of green roof installations, one filled with glass pumice (GP) and the other with composite metal oxide glass pumice (FMGP), on the simulated rainfall runoff treatment, the results are as follows:

[0061] GP and FMGP for NO3 - -N removal reaches equilibrium after a residence time of 5 hours or more; the second-stage FMGP packing effectively removes NO3. - The -N equilibrium adsorption capacity is the highest, at 0.140 mg·g⁻¹. -1 It is about 2.6 times that of the first-stage GP packing.

[0062] Modified glass pumice for PO4 3- -P can effectively remove PO4, FMGP is effective against PO4. 3- -P removal rate can reach up to about 85.45%.

[0063] The system is highly adaptable to changes in influent pollution load. The higher the influent pollution load, the greater the biomass of biofilm. In terms of removal rate, the average COD removal rate under high-load influent conditions is 7.04% higher than under low-load conditions.

[0064] Experiment Example 5: Performance Test of Pollution Treatment in Actual Rainfall Runoff

[0065] The results were obtained through four tests under real rainfall-runoff conditions. Figure 6 .

[0066] The system has a good purification capacity for COD in actual runoff rainwater. The COD removal rate is about 76.15% in the four influents.

[0067] The system showed good removal efficiency for ammonia nitrogen in actual stormwater runoff, with an average removal rate of 85.62%. This indicates that the system can effectively remove ammonia nitrogen because the magnesium / iron modified glass pumice surface contains free Mg. 2+ It can react with NH4 + and PO4 3- A chemical reaction occurs, and the magnesium / iron modified glass pumice has a larger specific surface area, which can support more nitrifying bacteria and enhance nitrification.

[0068] In actual stormwater runoff, the treatment effect of TN after system purification is unstable, fluctuating between 63% and 70%, with an average removal rate of 68.50%.

[0069] The device demonstrates excellent removal efficiency of phosphorus (TP) from actual stormwater runoff, achieving removal rates exceeding 89.8%. Particulate phosphorus in actual stormwater runoff can be removed through the filtration and adsorption of the substrate, while dissolved phosphorus is primarily removed by microbial activity. The upper layer of pumice contains a large number of phosphorus-laden bacteria with strong reoxygenation capabilities, allowing polyphosphate-accumulating bacteria to effectively absorb phosphorus. Simultaneously, the planting soil layer contains Fe... 3+ Mg 2+ Can be used with PO4 3- A chemical reaction occurs, and FMGP reacts with PO4. 3-It has electrostatic adsorption properties, and through the above synergistic effect, it can effectively remove TP from actual rainwater runoff.

[0070] Overall results show that the system has good treatment effects on various pollutants in actual stormwater runoff. The removal rates for ammonia nitrogen and total phosphorus (TP) are both above 80%, and the removal rate for COD is above 70%. Simultaneously, the system also effectively treats NO3. - The removal rates of -N and TN are close to 70%. The effluent meets the water quality standards for rainwater reuse in landscaping, car washing, road watering, and other applications.

[0071] As described above, although the invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the invention itself. Various changes in form and detail may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A modified glass pumice, characterized in that... It comprises the following components: a glass pumice matrix, artificial zeolite loaded on the surface and pores of the matrix, and magnesium-iron composite metal oxides coated on the surface of the artificial zeolite and the glass pumice matrix.

2. The modified glass pumice according to claim 1, characterized in that: The mass fractions of each component in the modified glass pumice are as follows: glass pumice matrix: 71.4%–74.1%, artificial zeolite: 14.3%–14.8%, and magnesium-iron composite metal oxide: 11.1%–14.3%.

3. A method for preparing modified glass pumice as described in any one of claims 1 to 2, characterized in that... Includes the following steps: Step 1, Zeolite loading: Artificial zeolite is dispersed in water to form a suspension, glass pumice is added and shaken to adsorb, and then dried to obtain glass pumice loaded with zeolite. Step 2, Preparation of mixed solution: Mix MgCl2 solution and FeCl3 solution, and adjust pH to 6.0; Step 3, Metal Salt Loading: The glass pumice with zeolite loading obtained in Step 1 is immersed in the mixed solution of Step 2, shaken, and filtered for separation; Step 4, calcination and curing: The separated material is dried and calcined at 500℃ for 3 hours under nitrogen protection to obtain modified glass pumice loaded with zeolite-magnesium iron composite metal oxide.

4. The application of the modified glass pumice prepared as described in claim 3 in a water treatment system.

5. An application of the modified glass pumice as described in claim 4 in a water treatment system, characterized in that: The water bodies in the water treatment system include rainwater, sewage, and seawater.

6. A direct rainwater recycling system for green roofs based on the modified glass pumice prepared as described in claim 3, characterized in that: The green roof rainwater direct reuse system includes a green roof and a recycling device on one side; a roof layer (2) is provided on one side of the green roof and a recycling device is provided on the other side. The green roof is divided into a first-level green roof and a second-level green roof by a retaining wall (4). The rainwater collected by the roof layer (2) enters the first-level green roof through the inlet pipe (3). After purification, the runoff enters the second-level green roof for secondary purification through the connecting pipe (9). After secondary purification, the runoff flows by gravity to the ground clear water pool through the recycling device.

7. The modified glass lightweight stone green roof rainwater direct recycling system according to claim 6, characterized in that: The first-level green roof and the second-level green roof, from bottom to top, include a floor slab bearing layer (1), a leveling layer (5), an SBS waterproof layer (6), a root penetration resistant isolation layer (7), a modified glass lightweight stone planting layer (8), and plants (14); the modified glass lightweight stone planting layer (8) is made of modified glass lightweight stone, the thickness of the modified glass lightweight stone planting layer (8) is 200-400mm, and the particle size of the modified glass lightweight stone is 10-30mm.

8. The modified glass lightweight stone green roof rainwater direct recycling system according to claim 6, characterized in that: The recycling device includes an inlet pipe (3) installed below the retaining wall of the first-level green roof. The inlet pipe (3) is connected to the drain pipe (10) below the retaining wall of the second-level green roof through a connecting pipe (9). The outlet of the drain pipe (10) is connected to the collection trough (13). The collection trough (13) is installed between the retaining wall and the outer wall of the second-level green roof. A rainwater hopper (11) is installed below the collection trough (13). The rainwater hopper (11) is connected to the ground clear water pool through a rainwater downpipe (12).

9. The modified glass lightweight stone green roof rainwater direct recycling system according to claim 8, characterized in that: The collection tank (13) is filled with glass pumice of different particle sizes in layers. The lower layer is filled with glass pumice with a particle size of 10-15mm, and the upper layer is filled with gravel with a particle size of 15-25mm.

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