Underground infiltration system for sewage by regulating phosphorus cycle to improve denitrification efficiency

Abstract

The application relates to the sewage treatment technical field and discloses a sewage underground infiltration system for improving denitrogenation efficiency by regulating and controlling phosphorus circulation, which comprises a reactor main body, a composite substrate filled in the reactor main body, an aerobic zone arranged at the upper portion of the reactor main body, a facultative zone arranged at the middle portion of the reactor main body and an anaerobic zone arranged at the bottom of the reactor main body. In the aerobic zone, nitrifying bacteria are added to enhance nitrification, and the nitrification is intensified by using phosphorus source released by phosphorus solubilizing bacteria; in the facultative zone, nitrifying-denitrifying bacteria are added to increase the number of denitrogenation microorganisms, and the phosphorus source of the denitrogenation bacteria is increased by using phosphorus solubilizing bacteria and phosphate-reducing bacteria, so that the nitrification and denitrification intensity is increased; in the anaerobic zone, the microelectric field generated by the composite substrate is used to supplement the denitrification electron donor, denitrifying bacteria are added to enhance the number of denitrogenation microorganisms, the phosphorus source of the denitrification bacteria is increased by using phosphate-reducing bacteria, and the denitrification intensity is increased.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a wastewater underground infiltration system that improves denitrification efficiency by regulating the phosphorus cycle. Background Technology

[0002] As a land treatment technology, underground infiltration systems are widely used in wastewater treatment due to their advantages in construction and operation costs and maintenance management. One of the core objectives of this technology is the removal of nutrients such as nitrogen and phosphorus from wastewater, with total nitrogen removal being a key indicator for evaluating its treatment efficiency. Total nitrogen removal typically relies on the sequential processes of microbial-mediated nitrification and denitrification.

[0003] Achieving stable and efficient nitrogen removal in existing underground wastewater infiltration systems faces a series of technical challenges. Nitrification requires an aerobic environment, while denitrification requires anoxic or anaerobic environments, creating a conflict in their oxygen requirements. In actual operation, factors such as fluctuations in influent hydraulic load and substrate blockage make it difficult to establish and maintain clearly defined and functionally stable aerobic and anaerobic zones within the system. Fluctuations in redox conditions or unclear zoning directly inhibit the activity of nitrifying or denitrifying bacteria, leading to interruptions or inefficiencies in the nitrogen removal process chain.

[0004] Furthermore, even if an aerobic environment is established locally within the system, the efficiency of the nitrification process may still be constrained by other conditions. The growth and metabolic activities of nitrifying microorganisms require not only oxygen but also a suitable supply of nutrients, including bioavailable phosphorus. In some soil or substrate environments, phosphorus is mostly fixed in the form of insoluble phosphate, which cannot be directly absorbed and utilized by nitrifying bacteria, thus constituting a limiting factor in the nitrification reaction and affecting the conversion rate and amount of ammonia nitrogen to nitrate.

[0005] Furthermore, the subsequent denitrification stage relies on a sufficient electron donor, typically an organic carbon source in the wastewater. However, many wastewaters to be treated, especially primary-treated municipal wastewater, have a low carbon-to-nitrogen ratio, meaning the organic matter content is insufficient relative to the total nitrogen content. This lack of carbon source leads to insufficient electron donor supply, preventing the complete reduction of nitrates produced in the aerobic zone. This results in incomplete denitrification, limiting the system's total nitrogen removal capacity. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a wastewater underground infiltration system that improves denitrification efficiency by regulating the phosphorus cycle. This solves the problem that the overall denitrification efficiency in existing wastewater underground infiltration systems is poor due to the instability of aerobic and anaerobic zones, the limitation of nitrification process on available phosphorus supply, and the limitation of denitrification process on carbon source electron donors.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a wastewater underground infiltration system that enhances denitrification efficiency by regulating the phosphorus cycle, comprising:

[0008] Reactor body;

[0009] A composite matrix filling the reactor body;

[0010] The aerobic zone is located at the top of the reactor body;

[0011] An anoxic zone is located in the middle of the reactor body;

[0012] And an anaerobic zone located at the bottom of the reactor body;

[0013] in,

[0014] Below the water inlet and distribution device, there is an impermeable dish, which is used to force the sewage flow to be constructed as an upward aerobic flow and a downward flow. The downward flow flows through the facultative anaerobic zone and the anaerobic zone in sequence, thereby forming an upper aerobic zone, a middle facultative anaerobic zone and a lower anaerobic zone in the reactor body.

[0015] The upper aerobic zone is inoculated with nitrifying bacteria and phosphate-solubilizing bacteria;

[0016] The middle anaerobic zone is inoculated with nitrifying bacteria, phosphate-solubilizing bacteria, denitrifying bacteria, and phosphate-reducing bacteria.

[0017] The lower anaerobic zone is inoculated with denitrifying bacteria and phosphate-reducing bacteria;

[0018] Preferably, the water inlet and distribution device is a cross-shaped perforated water distribution pipe, which is wrapped in a gravel layer; the impermeable dish is located directly below the gravel layer.

[0019] Preferably, the composite matrix is ​​composed of black soil and Si-Al porous filler containing elements such as iron and carbon.

[0020] Preferably, the Si-Al porous packing material containing iron and carbon elements is used to form an Fe-C micro-electric field in an immersion environment, providing additional electrons for the anaerobic denitrifying bacteria.

[0021] Preferably, the mass ratio of the black soil to the Si-Al porous filler is 9:1.

[0022] Preferably, a facultative anaerobic zone is provided between the upper aerobic zone and the lower anaerobic zone, and the facultative anaerobic zone is simultaneously inoculated with the aerobic nitrifying bacteria, phosphate-solubilizing bacteria and anaerobic denitrifying bacteria.

[0023] Preferably, the lower anaerobic zone or the facultative anaerobic zone is further inoculated with phosphate-reducing bacteria.

[0024] Preferably, the inoculation amount of each functional strain in each zone is 3% of the mass of black soil filling the functional zone.

[0025] A wastewater underground infiltration method for improving nitrogen removal efficiency by regulating the phosphorus cycle includes the following steps:

[0026] Wastewater is introduced into the inlet and distribution device. Through the regulation of the impermeable plate, the wastewater permeates upward to form an aerobic environment and permeates downward to form an anaerobic environment.

[0027] In the anaerobic environment, denitrifying bacteria are used to denitrify the nitrification products. Furthermore, phosphate-reducing bacteria are used to increase the phosphorus source for the denitrifying bacteria, thereby increasing the denitrification intensity.

[0028] Preferably, in the anaerobic environment, the micro-electric field formed by the Si-Al porous packing material in the composite matrix provides additional electrons to enhance denitrification.

[0029] This invention provides a wastewater underground infiltration system that improves denitrification efficiency by regulating the phosphorus cycle.

[0030] It has the following beneficial effects:

[0031] 1. This invention forcibly reconstructs the hydraulic flow pattern within the system by placing an impermeable dish below the water inlet and distribution device, forming a stable upward aerobic flow and downward anaerobic flow. This structure ensures clear spatial definition and long-term stability of environmental conditions between the upper aerobic zone and the lower anaerobic zone. This physical zoning provides the necessary environment for the stable survival and functioning of functionally specialized aerobic and anaerobic microorganisms, solving the problem in traditional infiltration systems where unstable hydraulic flow leads to blurred or alternating redox zones, thus affecting the effectiveness of different functional microbial communities.

[0032] 2. This invention establishes an internal coupling relationship between the phosphorus and nitrogen cycles by inoculating phosphate-solubilizing bacteria and aerobic nitrifying bacteria at specific sites in the upper aerobic zone. The phosphate-solubilizing bacteria can release solid phosphorus from the composite matrix in situ, providing a sufficient and continuous bioavailable phosphorus source for the growth and metabolism of aerobic nitrifying bacteria. In the lower anaerobic zone, phosphate-reducing bacteria are used to increase the phosphorus source for denitrifying bacteria, thereby increasing the denitrification intensity. Simultaneously, phosphate-reducing bacteria in the lower anaerobic zone further increase the phosphorus source for denitrifying bacteria, increasing the denitrification intensity.

[0033] 3. This invention utilizes Si-Al porous packing material containing iron and carbon as part of a composite matrix to construct an Fe-C micro-electric field in the lower anaerobic zone. This micro-electric field can generate electrons, serving as inorganic electron donors for the denitrification process. This mechanism provides anaerobic denitrifying bacteria with a backup electron source besides the organic matter in the wastewater itself, solving the technical bottleneck of incomplete denitrification due to insufficient carbon sources in wastewater, and enhancing the system's adaptability to fluctuations in influent water quality and the stability of overall nitrogen removal efficiency.

[0034] 4. This invention organically integrates a specific hydraulic control structure, spatially zoned microbial communities, and a composite matrix with electrochemical functions into a single reactor body. The system's physical zoning, the driving effect of phosphorus cycling on nitrification, and the supplementary effect of the micro-electric field on denitrification are interconnected and complementary. This integrated design allows the two key nitrogen removal steps of nitrification and denitrification to be enhanced within a single system, forming a complete treatment chain and improving the overall nitrogen removal function of the system. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of SWIS A of the present invention;

[0036] Figure 2 This is a schematic diagram of SWIS B of the present invention;

[0037] Figure 3 This is a schematic diagram of the NH4+ and TN concentrations in the effluent of the present invention;

[0038] Figure 4 This is a schematic diagram of the COD concentration in the effluent of the present invention;

[0039] Figure 5 This is a system architecture diagram of the present invention. Detailed Implementation

[0040] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] Please see the appendix Figure 1 - Appendix Figure 5 This invention provides a wastewater underground infiltration system that improves denitrification efficiency by regulating the phosphorus cycle and a method for wastewater treatment using the system.

[0042] In one specific embodiment, the system may include the following parts: a reactor body; a composite matrix filled in the reactor body; an aerobic zone located at the top of the reactor body; an anaerobic zone located in the middle of the reactor body; and an anaerobic zone located at the bottom of the reactor body; wherein, an impermeable dish is provided below the water inlet and water distribution device to force the sewage flow into an upward aerobic flow and a downward aerobic flow, the downward flow flowing sequentially through the anaerobic zone and the anaerobic zone, thereby forming an upper aerobic zone, a middle anaerobic zone and a lower anaerobic zone within the reactor body;

[0043] The upper aerobic zone is inoculated with aerobic nitrifying bacteria and phosphate-solubilizing bacteria;

[0044] The middle facultative anaerobic zone is inoculated with aerobic nitrifying bacteria, phosphate-solubilizing bacteria, denitrifying bacteria, and phosphate-reducing bacteria;

[0045] The lower anaerobic zone is inoculated with denitrifying bacteria and phosphate-reducing bacteria.

[0046] The components, preparation method, and working principle of this embodiment will be described in detail below.

[0047] I. Construction of Physical Architecture and Hydraulic Control Structure

[0048] The physical architecture of this embodiment aims to create a stable and functionally differentiated hydraulic flow field and redox environment inside the reactor through a specific combination of structures.

[0049] 1.1 Reactor Body

[0050] The reactor body is a vertically positioned cylindrical container, composed of three independently detachable modules (upper, middle, and lower), connected by stainless steel flanges. The reactor has a total height of 1.8m and an inner diameter of 0.3m. The main body is made of plexiglass, which possesses good mechanical strength, corrosion resistance, and high light transmittance. Rubber gaskets are installed at each flange connection, secured with stainless steel bolts and nuts to ensure the airtightness and watertightness of the entire device under operating pressure. To prevent light from entering the reactor and inhibit the growth of photosynthetic autotrophic microorganisms, the outer surface of the reactor is completely covered with double-layered opaque aluminum foil.

[0051] To enable monitoring of the internal state of the system along the process, sealed sampling ports are installed on the outer wall of the reactor along the vertical axis from the top (defined as 0cm) downwards at depths of 30cm, 50cm, 70cm, 90cm, 110cm, 130cm and 150cm. Each sampling port is equipped with a controllable sampling valve.

[0052] 1.2 Hydraulic Regulation Structure

[0053] The hydraulic control structure includes a water inlet and distribution device and an impermeable dish as the core component.

[0054] Water Inlet and Distribution System: The system's inlet water is drawn from an external inlet tank by an adjustable-speed peristaltic pump that provides a constant low flow rate, and then delivered to the reactor interior via a corrosion-resistant polyethylene hose. The end of the hose connects to a cross-shaped perforated PVC distribution pipe, which is horizontally positioned 60 cm from the top of the reactor. To ensure uniform wastewater distribution and prevent substrate particles from clogging the perforations, this distribution pipe is completely encased in a 10 cm thick layer of washed gravel (10 mm–20 mm in diameter), forming the water distribution zone.

[0055] Impermeable dish: A waterproof dish made of an inert material (such as polypropylene) is placed directly below the gravel layer in the water distribution area. The dish has an upward-opening, shallow, disc-shaped structure with an outer diameter smaller than the reactor's inner diameter, maintaining a uniform annular gap between it and the reactor's inner wall. This waterproof dish physically prevents the direct vertical infiltration of wastewater under gravity.

[0056] II. Preparation and Filling of Functionalized Composite Matrix

[0057] In this embodiment, the composite matrix filling the reactor body is composed of natural black soil and Si-Al porous filler, which is intended to provide a carrier and some reactants for biochemical reactions.

[0058] 2.1 Pretreatment of matrix components

[0059] Natural black soil: taken from the topsoil of suburban farmland. Its pretreatment steps include: a) air drying to constant weight to remove excess moisture; b) manual sieving to remove visible impurities such as stones and plant roots; c) grinding with a mechanical crusher to break up soil aggregates; d) sieving the ground soil through a 100-mesh standard sieve to obtain fine soil powder with uniform particle size.

[0060] Si-Al porous fillers are made from industrial waste tailings containing iron, silicon, aluminum, and carbon through a high-temperature sintering process. This process results in granular materials with high porosity and a stable physical structure.

[0061] 2.2 Preparation and Filling of Composite Matrix

[0062] The pretreated black soil powder and Si-Al porous filler were placed in a vertical mixer at a mass ratio of 9:1 and dry-mixed until they were macroscopically homogeneous. Then, the prepared composite matrix was layered and filled into the reactor body.

[0063] III. Preparation and Inoculation of Spatial Partition Microorganisms

[0064] In this embodiment, based on the constructed redox partitioning, the composite matrix is ​​inoculated with functional microorganisms in a stratified and targeted manner. The functional strains used can be dominant strains screened and enriched from activated sludge in wastewater treatment plants, or commercially available high-concentration microbial agents.

[0065] 3.1 Preparation of inoculum solution

[0066] The freeze-dried powders or high-concentration mother liquors of the required aerobic nitrifying bacteria, phosphate-solubilizing bacteria, anaerobic denitrifying bacteria, and phosphate-reducing bacteria are activated and amplified with the corresponding culture media to prepare highly active liquid bacterial suspensions.

[0067] 3.2 Regional vaccination method

[0068] The inoculation process and the substrate filling process are carried out simultaneously, and the specific steps are as follows:

[0069] Lower anaerobic zone (120-180cm): Take the required mass of composite substrate for this zone and place it in a clean container. Spray the calculated volume of anaerobic denitrifying bacteria suspension and phosphate-reducing bacteria suspension (the total inoculation biomass of the two strains is set at 3% of the dry weight of the black soil in this layer) onto the substrate and stir thoroughly to ensure the bacterial solution is evenly adhered to the surface of the substrate particles. Subsequently, fill the mixture to the designated height at the bottom of the reactor.

[0070] Anoxic zone (60-120cm): Using a method similar to the previous step, a suspension of four types of bacteria—aerobic nitrifying bacteria, phosphate-solubilizing bacteria, anaerobic denitrifying bacteria, and phosphate-reducing bacteria—was thoroughly mixed with the required mass of composite substrate for this layer before being filled. The inoculation biomass for each strain was set at 3% of the dry mass of the black soil in this layer.

[0071] Upper aerobic zone (0-60cm): The aerobic nitrifying bacteria suspension and the phosphate-solubilizing bacteria suspension are thoroughly mixed with the required mass of composite substrate for this layer and then filled to the designated height at the top of the reactor. The total inoculation biomass of the two strains is set at 3% of the dry weight of the black soil in this layer. During filling, small batches should be added and moderately compacted to ensure uniformity and density of the substrate filling in each layer.

[0072] IV. Overall System Operation Mode and Working Principle

[0073] The system operation in this embodiment is divided into two stages: startup and acclimatization, and stable operation. Its core working principle is to use physical processes guided by a specific structure to drive and regulate a multi-species, spatially separated biochemical reaction chain.

[0074] 4.1 Initiation of the domestication phase

[0075] After the system is loaded and inoculated, a 20-30 day start-up acclimatization period is first implemented. Initially, simulated wastewater at 50% of the designed influent concentration and hydraulic load at 50% of the designed flow rate is continuously fed in to allow the functional bacterial communities to adapt to the substrate environment and begin to proliferate. During this period, the water quality parameters of the influent and effluent are monitored daily. Once the system effluent indicators tend to stabilize, the influent concentration and flow rate are gradually increased to the designed levels until the system enters a stable operating phase.

[0076] 4.2 Working principle during stable operation phase

[0077] Step 1: Establishing Hydraulic Zoning and Redox Gradients

[0078] Wastewater is pumped into the water distribution device by a peristaltic pump. Under the physical regulation of the impermeable dish, the water flow forms two main paths within the reactor:

[0079] Upward flow and formation of the aerobic zone: Most of the water flow slowly penetrates the composite matrix area to a depth of 0-60cm in the upper part through capillary action. Because this area is close to the atmosphere and the water turnover rate is low, oxygen can be fully dissolved and diffused, thus forming a stable aerobic zone.

[0080] Downflow and the formation of the anaerobic zone: When the water level in the distribution zone exceeds the edge of the impermeable dish, excess wastewater overflows from the annular gap between the dish edge and the inner wall of the reactor, and under the influence of gravity, it penetrates downwards into the composite matrix area at a depth of 60-180cm. Due to the oxygen consumption of the aerobic microorganisms in the upper layer and the fact that this area is far from atmospheric recharge, the oxygen concentration drops sharply, thus forming an anoxic / anaerobic zone.

[0081] Step 2: Co-nitrification process in the upper aerobic zone

[0082] In the upper aerobic zone, the following processes occur simultaneously:

[0083] Phosphate-solubilizing effect: Inoculated phosphate-solubilizing bacteria secrete organic acids (such as citric acid and gluconic acid) and phosphatases. These secretions can convert the fixed, poorly bioavailable, insoluble inorganic phosphates (such as iron phosphate and calcium phosphate) and organic phosphorus in black soil into soluble orthophosphates that can be directly absorbed and utilized by microorganisms.

[0084] Enhanced nitrification: The aerobic nitrifying bacteria in this area experience enhanced growth and metabolic activity after receiving ample phosphorus from phosphate-solubilizing bacteria (essential for ATP and nucleic acid synthesis). Under oxygen-rich conditions, they oxidize ammonia nitrogen in wastewater to nitrate in two steps:

[0085] Nitrification reaction:

[0086] Nitrification reaction:

[0087] Nitrification reaction:

[0088] The product of this process—high concentrations of nitrates—migrates to lower layers with the water flow.

[0089] Step 3: Co-denitrification process in the lower anaerobic zone

[0090] Water containing nitrates flows through the facultative anaerobic zone and then enters the lower anaerobic zone. Under this anoxic / anaerobic environment, the following processes occur:

[0091] Biological denitrification: Anaerobic denitrifying bacteria in this area utilize the nitrates produced in the upper layer as the final electron acceptor to carry out dissimilar denitrification, gradually reducing it to nitrogen gas, which then escapes from the system. The electron donor for this process is mainly residual organic matter in the wastewater.

[0092]

[0093] Synergistic effect of micro-electrolysis: When organic matter (electron donor) in wastewater is insufficient, the Fe-C micro-electrolysis effect of the Si-Al porous packing in the composite matrix is ​​initiated. Iron, acting as the anode, loses electrons (Fe-2e). - →Fe 2+ These in-situ generated electrons can serve as inorganic electron donors, directly utilized by denitrifying bacteria to supplement the reducing power required for biological denitrification. The reaction can be represented as follows:

[0094]

[0095] Microenvironment regulation: The metabolic activities of phosphate-reducing bacteria in this region help maintain and optimize the anaerobic microenvironment, providing support for the efficient operation of denitrifying bacteria.

[0096] Step 4: Water Collection

[0097] After undergoing multi-stage and multi-path synergistic purification, the water flow eventually converges at the bottom of the reactor to collect the effluent, which is then discharged from the system through a perforated water collection pipe.

[0098] Through the above structural design and operation mode, this invention couples the biogeochemical cycle of phosphorus with the nitrogen removal process, achieving highly efficient removal of nitrogen from wastewater. This detailed description of the specific embodiments provides those skilled in the art with sufficient information to implement the invention and supports the scope of protection defined by the foregoing claims.

[0099] Please see the appendix Figure 3 -Appendix Figure 4This experiment, through operating wastewater infiltration systems with different proportions of added bacterial strains, found that a SWIS substrate addition ratio of 3% resulted in the lowest effluent concentration and the best treatment effect. The bacterial addition ratios for columns 1, 2, and 3 were 1%, 3%, and 5%, respectively. The system reached stability after 20 days of operation. The effluent COD, NH4+, and TN concentrations are shown in the attached figure. Figure 3 , 4 As shown, by Figure 3 , Figure 4 It can be seen that column 2 had the lowest concentrations of COD, NH4+, and TN in the effluent, indicating the best treatment effect. Therefore, it is concluded that when the addition ratio of SWIS substrate is 3%, the wastewater treatment effect of SWIS is optimal.

[0100] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A wastewater underground infiltration system that improves denitrification efficiency by regulating the phosphorus cycle, characterized in that, include: Reactor body; A composite matrix filling the reactor body; A water inlet and water distribution device is installed on the upper part of the reactor body; And an effluent collection device located at the bottom of the reactor body; in, Below the water inlet and distribution device, an impermeable dish is provided to force the sewage flow into an upward aerobic flow and a downward anaerobic flow, thereby forming an upper aerobic zone and a lower anaerobic zone within the reactor body. The upper aerobic zone is inoculated with aerobic nitrifying bacteria and phosphate-solubilizing bacteria; The lower anaerobic zone is inoculated with anaerobic denitrifying bacteria. The composite matrix is ​​composed of black soil and Si-Al porous filler containing iron and carbon elements; A transition zone is also provided between the upper aerobic zone and the lower anaerobic zone, and the aerobic nitrifying bacteria, phosphate-solubilizing bacteria and anaerobic denitrifying bacteria are inoculated in the transition zone at the same time. Phosphate-reducing bacteria are also inoculated in the lower anaerobic zone or the transition zone.

2. The wastewater underground infiltration system for improving denitrification efficiency by regulating the phosphorus cycle according to claim 1, characterized in that, The water inlet and distribution device is a cross-shaped perforated water distribution pipe, which is wrapped in a gravel layer; the impermeable dish is located directly below the gravel layer.

3. The wastewater underground infiltration system for improving denitrification efficiency by regulating the phosphorus cycle according to claim 1, characterized in that, The Si-Al porous packing material containing iron and carbon elements is used to form an Fe-C micro-electric field in an immersion environment, providing additional electrons for the anaerobic denitrifying bacteria.

4. A wastewater underground infiltration system for improving denitrification efficiency by regulating phosphorus cycling, as described in claim 1, is characterized in that... The mass ratio of the black soil to the Si-Al porous filler is 9:

1.

5. A wastewater underground infiltration system for improving denitrification efficiency by regulating phosphorus cycling, as described in claim 1, is characterized in that... The inoculation amount of each functional strain in the transition zone is 3% of the mass of black soil filling the functional zone.

6. A method for improving denitrification efficiency through phosphorus cycle regulation in underground wastewater infiltration, used in the underground wastewater infiltration system for improving denitrification efficiency through phosphorus cycle regulation according to any one of claims 1-5, characterized in that, Includes the following steps: Wastewater is introduced into the inlet and distribution device. Through the regulation of the impermeable plate, the wastewater permeates upward to form an aerobic environment and permeates downward to form an anaerobic environment. In the aerobic environment, the soluble phosphorus released by phosphate-solubilizing bacteria is used to synergistically enhance the nitrification of ammonia nitrogen by the aerobic nitrifying bacteria, so as to produce nitrification products. In the anaerobic environment, anaerobic denitrifying bacteria are used to denitrify the nitrification products.

7. A wastewater underground infiltration method for improving denitrification efficiency by regulating phosphorus cycling, as described in claim 6, is characterized in that... In the anaerobic environment, the micro-electric field formed by the Si-Al porous packing material in the composite matrix provides additional electrons to enhance denitrification.

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