Physical adsorption and biological denitrification combined river overflow port treatment process

Abstract

The invention discloses a physical adsorption and biological denitrification combined river channel overflow port treatment process which is characterized in that a water inlet tank, a first-stage filtration and oxidation zone, a second-stage filtration and oxidation zone, a third-stage filtration and oxidation zone and a fourth-stage filtration zone are sequentially arranged from upstream to downstream along the water flow direction of a river channel; the first-stage filtration and oxidation area is provided with a first-stage filler bin and a first-stage contact oxidation bin, the second-stage filtration and oxidation area is provided with a second-stage filler bin and a second-stage contact oxidation bin, and the third-stage filtration and oxidation area is provided with a third-stage filler bin and a third-stage contact oxidation bin; the filler bins in the first-stage filtration and oxidation zone, the second-stage filtration and oxidation zone and the third-stage filtration and oxidation zone are provided with phosphorus removal ceramsite fillers; the fourth-stage filtering area is filled with an activated carbon filler layer and is used for further purifying the effluent. The occupied area can be reduced, the outlet water treatment efficiency of the discharge port is improved, and the operation cost is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of water treatment, and specifically relates to the technology for treating sewage discharged from outlets.

Background Art

[0002] River pollution control is one of the major environmental challenges faced globally. Especially in the southeastern region of China, affected by the monsoon climate, rainfall is concentrated in some periods, the problem of rainwater-sewage mixing is prominent, and the overflow volume is large, which exacerbates the deterioration of river water quality. At present, there is still a lack of effective means for treating rainwater overflows in this area. Traditional treatment processes have problems such as high costs and poor applicability, and existing in-situ pretreatment measures cannot meet the requirements of storage and treatment. Therefore, it is urgent to develop highly efficient and adaptable river pollution control technologies.

[0003] Polluted river water has characteristics such as the degree of pollution varying with the runoff, fast diffusion of pollutants, and great pollution hazards. Among many treatment technologies, the "three-pond two-dam" system is a commonly used technology in the treatment of aquaculture tail water and is also a technology widely used in river water treatment at present. It consists of a "sedimentation tank + filter dam + aeration tank + filter dam + biological purification tank", and the system is divided into 3 units by two partitions, namely the overflow dam and the subsurface flow dam, to achieve the treatment of aquaculture water and make it meet the discharge standards or be recycled. The overflow dam can block sediment pollutants, increase surface flow, and improve the oxygen content in the water. The subsurface flow dam can block suspended pollutants and provide a low-oxygen environment to promote the growth of anaerobic water-purifying microorganisms, constructing aerobic and anaerobic microbial treatment modes to strengthen nitrification-denitrification, achieving the effect of purifying total nitrogen and total phosphorus, and being widely used in the treatment of aquaculture tail water, paddy field treatment, etc. However, the traditional "three-pond two-dam" technology has disadvantages such as large floor area, high energy consumption, short equipment life, high maintenance cost, increased operating cost due to the use of chemicals, long commissioning period, and poor shock resistance under the same water quality and quantity conditions.

[0004] In recent years, for the problem of river pollution control, there have been some related patented technologies. For example, Patent [CN201810799392.0] proposed a method for treating river pollution based on activated carbon adsorption. This method uses the adsorption characteristics of activated carbon to remove some pollutants in water, but the adsorption capacity of activated carbon is limited and regeneration is difficult, which limits its long-term application effect. Patent [CN114684926B] introduced a river water treatment process using the microbial immobilization technology. Although it improves the treatment efficiency of microorganisms for pollutants to a certain extent, the process of microbial immobilization is complex, the cost is high, and the stability needs to be improved. Patent [CN111659411A] is a river pollution control technology using the principle of photocatalytic oxidation. This technology requires specific light conditions and is greatly limited by environmental factors in practical applications.

[0005] Therefore, there is an urgent need for a method for treating river water pollution that optimizes the traditional treatment process of river overflow outlets and directly treats the pollution in situ according to the original river channel structure.

Summary of the Invention

[0006] Aiming at the deficiencies of the prior art, the technical problem to be solved by the present invention is to provide a treatment process for river overflow outlets that combines physical adsorption and biological denitrification, and solves the problems of large floor area, low treatment efficiency, and low shock load resistance in the traditional "three ponds and two dams" treatment process.

[0007] To solve the above technical problems, the present invention adopts the following technical solutions:

[0008] A treatment process for river overflow outlets that combines physical adsorption and biological denitrification, in which an inlet pool, a first-stage filtration and oxidation zone, a second-stage filtration and oxidation zone, a third-stage filtration and oxidation zone, and a fourth-stage filtration zone are sequentially arranged from upstream to downstream along the river water flow direction. The first-stage filtration and oxidation zone is provided with a first-stage packing bin and a first-stage contact oxidation bin, the second-stage filtration and oxidation zone is provided with a second-stage packing bin and a second-stage contact oxidation bin, and the third-stage filtration and oxidation zone is provided with a third-stage packing bin and a third-stage contact oxidation bin;

[0009] The inlet pool pre-treats the influent; the packing bins in the first-stage filtration and oxidation zone, the second-stage filtration and oxidation zone, and the third-stage filtration and oxidation zone play a dual role of physical filtration and chemical adsorption on the influent, so as to remove impurities and harmful components in the influent. The contact oxidation bin is provided with biological packing and an aeration pipe is arranged at the bottom for aeration, and microorganisms are used to biologically degrade organic matter and ammonia nitrogen in an aerobic environment;

[0010] The packing bins in the first-stage filtration and oxidation zone, the second-stage filtration and oxidation zone, and the third-stage filtration and oxidation zone are provided with phosphorus-removing ceramsite packing layers;

[0011] The fourth-stage filtration zone is filled with an activated carbon packing layer for further purifying the effluent.

[0012] Preferably, floating aquatic plants are arranged in the inlet pool for initially removing some pollutants in the influent.

[0013] Preferably, the inlet pool is provided with a grille for intercepting large particulate suspended matter in the influent.

[0014] Preferably, multiple packing bins and contact oxidation bins in the first-stage filtration and oxidation zone, the second-stage filtration and oxidation zone, and the third-stage filtration and oxidation zone are arranged alternately.

[0015] Preferably, the packing bins in the first-stage filtration and oxidation zone, the second-stage filtration and oxidation zone, and the third-stage filtration and oxidation zone are provided with a four-layer structure, which are, from bottom to top, a volcanic stone layer, a double-layer phosphorus-removing ceramsite and a sunflower seed slice layer.

[0016] Preferably, the activated carbon packing layer is located in the middle and lower part of the fourth-stage filtration zone, and a sunflower seed slice layer is provided in the upper part of the fourth-stage filtration zone.

[0017] Preferably, the first-stage filtration and oxidation zone, the second-stage filtration and oxidation zone, the third-stage filtration and oxidation zone, and the fourth-stage filtration zone are all independent standard module structures.

[0018] Preferably, the water inlet tank is an independent standard module structure and is provided with a water-facing surface inclined at 45°.

[0019] Preferably, air-blowing perforated pipes are provided in the packing bins in the first-stage filtration and oxidation zone, the second-stage filtration and oxidation zone, and the third-stage filtration and oxidation zone, and in the fourth-stage filtration zone, so as to regularly introduce compressed air through the air-blowing perforated pipes to backwash the packing.

[0020] Preferably, a water outlet trough is provided between the third-stage filtration and oxidation zone and the fourth-stage filtration zone, and a spraying device is arranged at the top of the water outlet trough for removing the floating foam remaining in the outlet water.

[0021] The present invention adopts the above technical solutions and has the following beneficial effects:

[0022] 1. The water inlet tank, the first-stage filtration and oxidation zone, the second-stage filtration and oxidation zone, the third-stage filtration and oxidation zone, and the fourth-stage filtration zone are sequentially arranged from upstream to downstream along the water flow direction of the river. Among them, the first-stage filtration and oxidation zone, the second-stage filtration and oxidation zone, and the third-stage filtration and oxidation zone perform in-depth treatment on the inlet water. The multi-layer packing in the packing bin plays a dual role of physical filtration and chemical adsorption on the inlet water, so as to remove impurities and harmful components in the inlet water. Biological packing is provided in the contact oxidation bin and an air pipe is arranged at the bottom for aeration, and microorganisms are used to biologically degrade organic matters and ammonia nitrogen in an aerobic environment. Therefore, pollutants can be removed in depth.

[0023] The present invention connects multiple regions in sequence to work together. Compared with the traditional "three ponds and two dams" technology, it reduces the floor area, improves the efficiency, and enhances the impact resistance.

[0024] 2. In the present invention, a phosphorus-removing ceramsite filler layer is provided in the filler bins of the first-stage filtration and oxidation zone, the second-stage filtration and oxidation zone, and the third-stage filtration and oxidation zone. The phosphorus-removing ceramsite has a spherical granular appearance and many micro-nano pores inside, and has the characteristics of many pores, high strength, large adsorption capacity, and fast adsorption rate. The ceramsite has a rough and porous surface in terms of physical microstructure, which is particularly suitable for the growth and reproduction of microorganisms on its surface. The internal structure presents a nano-level network structure with extremely strong adsorption. The ceramsite can release Fe 3 + in phosphorus-containing sewage, which can undergo a chemical reaction with PO43- to form a chemical bond. The phosphate ion can undergo a ligand exchange reaction with the hydroxyl group (-OH) on the surface of the phosphorus-removing ceramsite to form an inner-sphere complex. The formation of this chemical bond enables phosphorus to be firmly adsorbed on the surface of the Fe-based sludge ceramsite, thereby achieving phosphorus removal.

[0025] In the biological denitrification process of the phosphorus-removing ceramsite, especially when it comes to nitrification and denitrification reactions, electron transfer is a key step. The Fe-based sludge ceramsite can serve as a medium for electron transfer. Some Fe(Ⅱ) / Fe(Ⅲ) redox pairs can participate in the metabolic processes of nitrifying bacteria and denitrifying bacteria, accelerating the electron transfer rate, and thus improving the efficiency of nitrification and denitrification reactions.

[0026] The phosphorus-removing ceramsite has a large specific surface area and a suitable pore structure, providing good attachment growth sites for denitrifying microorganisms. Microorganisms can form biofilms on its surface and in the pores. This biofilm structure is conducive to the aggregation and synergy of microorganisms, improving the treatment ability of microorganisms for nitrogen pollutants. The active sites on the surface of the phosphorus-removing ceramsite can interact with the enzymes or metabolites secreted by microorganisms, serving as the active centers of microbial metabolism, enhancing the catalytic activity of enzymes, and promoting the transformation of nitrogen compounds. The iron ions on the surface of the ceramsite can bind to nitrifying enzymes, changing the spatial structure of the enzymes and making their oxidation of ammonia nitrogen more efficient.

[0027] 3. In the present invention, biological fillers are provided in the contact oxidation bins of the first-stage filtration and oxidation zone, the second-stage filtration and oxidation zone, and the third-stage filtration and oxidation zone. Microporous aeration pipes are laid at the bottom to aerate and oxygenate the sewage, and the sewage in the pool body is in a stirred state. The fillers are in a state of tumbling up and down in the pool to ensure full contact between the sewage and the fillers, avoiding the defect of uneven contact between the sewage and the fillers, increasing the oxygen transfer efficiency by more than 30%, and the contact efficiency between the biofilm and the sewage by more than 50%, greatly reducing the aeration energy consumption.

[0028] 4. The fourth-stage filtration zone of the present invention is used as an emergency safeguard measure, in which an activated carbon filler layer is filled to achieve discharge standards after adsorbing residual pollutants by activated carbon.

[0029] 5. In the filler bins of the first-stage filtration and oxidation zone, the second-stage filtration and oxidation zone, and the third-stage filtration and oxidation zone of the present invention, there is a four-layer structure, which from bottom to top are a volcanic stone layer, a double-layer phosphorus-removing ceramsite and a sunflower seed chip layer. They all have the properties of corrosion resistance, inertness, harmlessness to microorganisms, no inhibitory effect, no impact on the activity of microorganisms, strong hydrophilicity, a large amount of attached biofilm, and a fast filtration speed. And these materials all have good mechanical strength and compression performance, are not easily broken and collapsed, which helps to reduce the operation cost and maintenance cost.

[0030] 6. The first-stage filtration and oxidation zone, the second-stage filtration and oxidation zone, the third-stage filtration and oxidation zone, and the fourth-stage filtration zone in the present invention are all independent standard module structures. This enables the equipment to be flexibly combined and configured according to the actual needs of different sites. Compared with the traditional construction method, it can not only effectively reduce the on-site construction cost, but also greatly reduce the noise and dust pollution generated by on-site operations, and significantly shorten the project duration.

[0031] 7. The inlet water tank in the present invention is an independent standard module structure, and the water-facing surface is inclined at 45°. This design can effectively reduce the impact force of the water flow on the tank body, reduce the risk of damage to the equipment structure by the water flow, and extend the service life of the equipment.

[0032] 8. Air-blowing perforated pipes are provided in the filler bins of the first-stage filtration and oxidation zone, the second-stage filtration and oxidation zone, and the third-stage filtration and oxidation zone, and in the fourth-stage filtration zone. Compressed air is regularly introduced into the filler bins through the air-blowing perforated pipes to backwash the fillers. The impurities intercepted in the pores of the fillers can be blown up and carried out, preventing the fillers from being blocked and ensuring the treatment effect of the filler bins.

[0033] 9. The tail water treatment process of the present invention has a long service life, and the stable operation time is much higher than that of the traditional activated sludge method or the fixed biofilm method. Moreover, it is a modular component, which is convenient and rapid to replace, and the daily maintenance is also relatively simple, with a low operation cost.

[0034] These characteristics and advantages of the present invention will be detailedly disclosed in the following specific embodiments and drawings.

Description of the Drawings

[0035] The invention will be further described below with reference to the drawings:

[0036] Figure 1 It is the process flow diagram of the river pollution treatment process of the embodiment of the present invention;

[0037] Figure 2 It is the process flow diagram of the river pollution treatment process of the embodiment of the present invention;

[0038] Figure 3 It is the process flow diagram of the river pollution treatment process of the embodiment of the present invention;

[0039] Figure 4 It is the plan view of a reinforced concrete foundation;

[0040] Figure 5 It is the plan view of the top of the overall equipment frame;

[0041] Figure 6 It is the external elevation view of the equipment.

Specific Embodiments

[0042] The technical solutions of the embodiments of the present invention will be explained and described below with reference to the accompanying drawings of the embodiments of the present invention. However, the following embodiments are only the preferred embodiments of the present invention and not all of them. Based on the embodiments in the embodiments, other embodiments obtained by those skilled in the art without creative efforts all fall within the protection scope of the present invention.

[0043] Those skilled in the art can understand that, without conflict, the features in the following embodiments and implementation manners can be combined with each other.

[0044] The terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. For example, the terms such as "upper", "lower", "inner", "outer", etc. indicating the orientation or position relationship are only based on the orientation or position relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device / component referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they cannot be understood as a limitation to the present invention.

[0045] In the present invention, unless otherwise clearly specified and limited, the first feature being "on" or "under" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features between them. Moreover, the first feature being "above", "over" and "on" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely means that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "under" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely means that the horizontal height of the first feature is lower than that of the second feature.

[0046] In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first", "second" may explicitly or implicitly include at least one of such features.

[0047] The present invention develops a treatment process for river overflow outlets that combines physical adsorption and biological denitrification to overcome many problems existing in the traditional "three-pool two-dam" process and existing patented technologies, and provides a more effective solution for river pollution treatment.

[0048] The present invention is a method for treating river pollution water by in-situ treatment directly according to the original river structure. As Figures 1 to 6 shown, ecological treatment equipment for the outlet is arranged along the river. The ecological treatment equipment for the outlet includes an inlet tank 15 → a first-stage filtration and oxidation zone 11 → a second-stage filtration and oxidation zone 12 → a third-stage filtration and oxidation zone 13 → an outlet trough → a fourth-stage filtration zone 14, which are arranged successively from upstream to downstream along the water flow direction of the river. The suspended solids, phosphorus, etc. in the sewage discharged from the outlet are mainly treated through processes such as filtration, adsorption, contact oxidation, and plant adsorption. After treatment by this equipment, the main pollutants in the effluent, namely ammonia nitrogen, total phosphorus, and COD, are effectively reduced, and the overall pollution load of the river is reduced.

[0049] The ecological treatment equipment for the outlet adopts a modular quick-assembly structure. The interior of the equipment is divided into regions according to each treatment function, and corresponding functional modules are set for each functional region. Each functional region forms an overall device through segmented module assembly. A reinforced concrete foundation 10 is provided at its bottom. The first-stage filtration and oxidation zone, the second-stage filtration and oxidation zone, the third-stage filtration and oxidation zone, and the fourth-stage filtration zone of the inlet tank are all independent modular structures, and are installed on the reinforced concrete foundation by splicing. Mounting bases 104 for fixing the bottoms of each module are fixed on the reinforced concrete foundation through expansion bolts and can be bolt-fixed to the bottoms of each module. The reinforced concrete foundation is arranged on a gravel cushion layer. The gravel cushion layer can play a role in draining water and evenly dispersing pressure, while the reinforced concrete foundation provides a solid and stable support for the equipment, adapts to the silt geological conditions, and ensures the safe operation of the equipment in different geological environments.

[0050] Specifically, the first-stage filtration and oxidation zone, the second-stage filtration and oxidation zone, the third-stage filtration and oxidation zone, and the fourth-stage filtration zone are all independent rectangular modular structures, and the inlet tank is an independent right trapezoidal modular structure. This facilitates the splicing of each module on the reinforced concrete foundation. And the inlet tank is provided with a water-facing surface inclined at 45°. This design can effectively reduce the impact force of the water flow on the tank body, reduce the risk of damage to the equipment structure by the water flow, and extend the service life of the equipment.

[0051] Each functional area of the sewage outlet ecological treatment equipment is quickly assembled using prefabricated standard modules in sections. Each module is connected by high-strength bolts and sealant, with expansion joints reserved between modules and EPDM rubber strips filled. The module size, material, and process are unified, reducing construction quality problems caused by human factors; the number, length, and combination method of modules can be flexibly adjusted according to site conditions; factory prefabrication reduces on-site cutting, welding, and other operations, reducing noise, dust, and waste emissions; assembled construction reduces on-site labor requirements, and the comprehensive cost is reduced by 20%-30% compared with traditional processes.

[0052] Specifically, each module includes an overall framework built by fiberglass square pipes 101 and PP plates 103 as the outer wall and internal partitions. Pipe connectors 102 can be set between each section of fiberglass square pipes 101, which can be straight pipes, elbow pipes, tee pipes, etc., and are set according to needs. The overall framework uses corrosion-resistant fiberglass square pipes. Fiberglass material is light in weight, high in strength, and excellent in corrosion resistance, which can reduce the overall weight of the equipment and meet the structural support requirements at the same time. PP plates are mainly used for the outer wall and internal partitions of the equipment. PP plates have good chemical corrosion resistance, impact resistance, and insulation.

[0053] The inlet tank is used for pre-treating the influent. The packing bins in the first-stage filtration and oxidation zone, the second-stage filtration and oxidation zone, and the third-stage filtration and oxidation zone have a dual effect of physical filtration and chemical adsorption on the influent, so as to remove impurities and harmful components in the influent. Biological packing is provided in the contact oxidation tank and an aeration pipe 113 is provided at the bottom for aeration. Microorganisms are used to biologically degrade organic matter and ammonia nitrogen in an aerobic environment. An activated carbon packing layer is filled in the fourth-stage filtration zone for further purifying the influent.

[0054] The first-stage filtration and oxidation zone is provided with a first-stage packing bin 111 and a first-stage contact oxidation tank 112 (or called an aeration tank). The second-stage filtration and oxidation zone is provided with a second-stage packing bin 121 and a second-stage contact oxidation tank 122. The third-stage filtration and oxidation zone is provided with a third-stage packing bin 131 and a third-stage contact oxidation tank 132. And, the multiple packing bins and contact oxidation tanks in the first-stage filtration and oxidation zone, the second-stage filtration and oxidation zone, and the third-stage filtration and oxidation zone are staggered, specifically staggered perpendicular to the river direction.

[0055] The inlet tank pre-treats the influent; the packing bins in the first-stage filtration and oxidation zone, the second-stage filtration and oxidation zone, and the third-stage filtration and oxidation zone have a dual effect of physical filtration and chemical adsorption on the influent, so as to remove impurities and harmful components in the influent. Biological packing is suspended on the surface layer in the contact oxidation tank and an aeration pipe is provided at the bottom for aeration. Microorganisms are used to biologically degrade organic matter and ammonia nitrogen in an aerobic environment.

[0056] The packing bins in the first-stage filtration and oxidation zone, the second-stage filtration and oxidation zone, and the third-stage filtration and oxidation zone are provided with phosphorus-removing ceramsite fillers. The packing bins in the first-stage filtration and oxidation zone, the second-stage filtration and oxidation zone, and the third-stage filtration and oxidation zone have a four-layer structure, which are, from bottom to top, a volcanic stone layer, a double-layer phosphorus-removing ceramsite and a sunflower seed chip layer. Each type of filler is packed in ecological bags and then loaded in layers. The functions of the first to third-stage packing bins are as follows: they can intercept larger particulate impurities in water through physical filtration, and at the same time provide a place for microorganisms to attach and grow; they have a high adsorption and chemical precipitation removal ability for phosphorus in water; they can further filter and stabilize the water flow, and at the same time have a certain interception effect on fine particles in water.

[0057] The fourth-stage filtration zone is filled with an activated carbon packing layer 141 for further purifying the influent water. The activated carbon packing layer 141 is located in the middle and lower part of the fourth-stage filtration zone, and a sunflower seed chip layer 142 is provided in the upper part of the fourth-stage filtration zone. In this way, the fourth-stage filtration zone has a strong adsorption capacity for residual tiny particles, pigments, odor substances and some dissolved organic matters in water, can further purify the water quality, and ensure that the effluent water quality reaches high standards.

[0058] The biological fillers used in the contact oxidation bins in the first-stage filtration and oxidation zone, the second-stage filtration and oxidation zone, and the third-stage filtration and oxidation zone need to have a large specific surface area, can attach a large number of microorganisms, and form a biological film. Microorganisms grow and reproduce on the biological film, and decompose and metabolize organic matters and ammonia nitrogen in water. Its aeration pipe system uniformly introduces air into the contact oxidation bin through microporous aeration pipes, provides sufficient oxygen for microorganisms, maintains an aerobic environment, promotes the growth and metabolic activities of microorganisms, and improves the biodegradation efficiency.

[0059] Among them, the main function of the inlet water tank 15 is to balance the water volume, make the water flow entering the equipment relatively stable, and avoid impacting the subsequent treatment modules due to excessive water volume fluctuations. At the same time, the influent water is diverted into the first-stage filtration and oxidation zone through the overcurrent channels on both sides. Coarse and fine grids are respectively arranged in front of the overcurrent channels to intercept sundries including moss that is likely to grow in the anhydrous state of the pipeline and garbage in the pipe; the coarse and fine grids are designed as detachable cleaning structures, and the grids are fixed through limit devices, which is convenient for regularly cleaning the intercepted sundries and ensuring the filtering effect of the grids. In addition, floating plants 151 are planted in the inlet water tank to absorb and enrich pollutants in the water body to a certain extent. At the same time, the leaves of the floating plants float on the water surface, which can beautify the landscape and enhance the ornamental value.

[0060] Among them, an adjustable water-turning and water-blocking inserting plate (with adjustable height) is provided at the water inlet end of the water outlet tank, which plays a certain role in storing water, maintains the overall water level in the device during the non-overflow period, and ensures the normal survival of microorganisms in the contact oxidation tank. A spraying device is arranged at the top of the water outlet tank to eliminate the floating foam remaining in the water outlet.

[0061] Furthermore, air-blowing perforated pipes are provided in the packing bins of the first-stage filtration and oxidation zone, the second-stage filtration and oxidation zone, and the third-stage filtration and oxidation zone, as well as in the fourth-stage filtration zone. Compressed air is regularly introduced into the packing bins through the air-blowing perforated pipes to backwash the packing. The impurities intercepted in the pores of the packing are blown up and carried out to prevent the packing from being blocked and ensure the treatment effect of the packing bin. In addition, the entire air-blowing system also includes an air compressor and a pressure gauge. The air compressor provides compressed air with sufficient pressure and flow rate for the air-blowing perforated pipes to ensure effective backwashing of the packing bin; the pressure gauge is used to monitor the air pressure output by the air compressor in real time so that the operator can adjust the operating parameters of the air compressor according to the actual situation to ensure the backwashing effect.

[0062] Furthermore, fiberglass grating plates are provided at the tops of the packing bins in the first-stage filtration and oxidation zone, the second-stage filtration and oxidation zone, and the third-stage filtration and oxidation zone, as well as in the fourth-stage filtration zone. Staff can enter the interior of the packing bin through the fiberglass grating plates for maintenance, packing replacement and other operations, which provides convenience for equipment maintenance.

[0063] Among them, flow channels 16 are provided between the water inlet tank and the first-stage filtration and oxidation zone, between the first-stage filtration and oxidation zone and the second-stage filtration and oxidation zone, and between the second-stage filtration and oxidation zone and the third-stage filtration and oxidation zone. Therefore, the main treatment processes and functional zones are: water inlet tank → flow channel 1 → (first-stage packing bin + first-stage contact oxidation tank) → (second-stage packing bin + second-stage contact oxidation tank) → flow channel 2 → (third-stage packing bin + third-stage contact oxidation tank) → water outlet tank → fourth-stage filtration zone. Specifically, the water discharged from the outlet flows into the water inlet tank through a pipeline. In the water inlet tank, the coarse grille and the fine grille intercept large-particle suspended matters in the water in sequence. Subsequently, the water flow enters the first-stage packing bin through flow channel 1, and the water quality is preliminarily purified through physical filtration, chemical adsorption and other effects, and then enters the first-stage contact oxidation tank, where microorganisms are used to biologically degrade organic matters and ammonia nitrogen in an aerobic environment. After that, the water flow is split through flow channel 2 and then passes through the second-stage and third-stage packing bins and contact oxidation tanks in sequence for in-depth treatment to further remove pollutants. The treated water flows into the water outlet tank, and the floating foam is eliminated through the spraying equipment. Finally, the fourth-stage filtration zone is used as an emergency safeguard measure, and the residual pollutants are adsorbed by activated carbon and then discharged up to the standard.

[0064] In the above technical solution, the outlet ecological treatment equipment is connected to multiple regions in sequence to work collaboratively. Compared with the traditional "three ponds and two dams" technology, it reduces the floor area, improves the efficiency, and enhances the impact resistance ability.

[0065] Among them, the phosphorus-removing ceramsite can adopt the existing technology. Its appearance is spherical granular, with many micro-nano pores inside, and has the characteristics of many pores, high strength, large adsorption capacity, and fast adsorption rate. The ceramsite has the characteristics of rough surface and porous in physical microstructure, which is especially suitable for microorganisms to grow and reproduce on its surface. The internal presents a nano-scale network structure with extremely strong adsorption. The ceramsite can release Fe 3 + can undergo a chemical reaction with PO43- to form a chemical bond. The phosphate ion can undergo a ligand exchange reaction with the hydroxyl group (-OH) on the surface of the phosphorus-removing ceramsite to form an inner-sphere complex. The formation of this chemical bond enables phosphorus to be firmly adsorbed on the surface of the Fe-based sludge ceramsite, thereby achieving the removal of phosphorus.

[0066] In the biological denitrification process of the phosphorus-removing ceramsite, especially when it comes to nitrification and denitrification reactions, electron transfer is a key step. The Fe-based sludge ceramsite can serve as a medium for electron transfer. Some Fe(Ⅱ) / Fe(Ⅲ) redox pairs can participate in the metabolic processes of nitrifying bacteria and denitrifying bacteria, accelerating the electron transfer rate, thereby improving the efficiency of nitrification and denitrification reactions.

[0067] The phosphorus-removing ceramsite has a large specific surface area and a suitable pore structure, providing good attachment growth sites for denitrifying microorganisms. Microorganisms can form biofilms on its surface and in the pores. This biofilm structure is conducive to the aggregation and synergy of microorganisms, improving the ability of microorganisms to treat nitrogen pollutants. The active sites on the surface of the phosphorus-removing ceramsite can interact with the enzymes or metabolites secreted by microorganisms, can serve as the active center of microbial metabolism, enhance the catalytic activity of enzymes, and promote the conversion of nitrogen compounds. The iron ions on the surface of the ceramsite can bind to nitrifying enzymes, changing the spatial structure of the enzymes and making their oxidation of ammonia nitrogen more efficient.

[0068] In the present invention, biological fillers are provided in the contact oxidation tanks in the first-stage filtration and oxidation zone, the second-stage filtration and oxidation zone, and the third-stage filtration and oxidation zone. Microporous aeration pipes are laid at the bottom to aerate and oxygenate the sewage, and the sewage in the pool body is in a stirred state. The fillers are in a state of tumbling up and down in the pool to ensure full contact between the sewage and the fillers, avoiding the defect of uneven contact between the sewage and the fillers, increasing the oxygen transfer efficiency by more than 30%, and the contact efficiency between the biofilm and the sewage by more than 50%, greatly reducing the aeration energy consumption. A high-pressure vortex blower can be connected to the aeration pipe to provide sufficient air for the contact oxidation tank to meet the oxygen demand for the aerobic metabolism of microorganisms.

[0069] The fourth - stage filtration area of the present invention serves as an emergency safeguard measure, filled with an activated - carbon packing layer. After the residual pollutants are adsorbed by the activated carbon, the effluent is discharged up to the standard.

[0070] Implementation Case 1:

[0071] A pre - treatment project for an overflow outlet in a certain street of Qiantang District, Hangzhou City, Zhejiang Province: In this embodiment, the rain - sewage overflow outlet is taken as the experimental object, and a new - type overflow - outlet pre - treatment device is designed to regulate and treat the discharged water from the outlet. In this scheme, a new - type outlet pre - treatment device is designed in Hezhuang Sub - district, adopting a river - pollution treatment process combining physical adsorption and biological denitrification, including an inlet tank → the first - stage filtration and oxidation area → the second - stage filtration and oxidation area → the third - stage filtration and oxidation area → an outlet trough → the fourth - stage filtration area, which are connected in sequence from front to back.

[0072] The effective volume of the inlet tank is 10m 3 , and the hydraulic retention time is set to 1 h. It is mainly used for the preliminary precipitation of large - particle suspended solids, balancing the water quality and quantity of the influent, and reducing the impact on the subsequent treatment units. Coarse and fine grids are installed in the tank to intercept larger floating objects. The sizes and structures of the first - stage filtration and oxidation area, the second - stage filtration and oxidation area, and the third - stage filtration and oxidation area are the same.

[0073] Experimental Results and Analysis

[0074] After 3 - month continuous operation monitoring, during the peak rainy - season overflow period, the removal rate of COD by this process reaches more than 80%, the total - nitrogen removal rate reaches more than 75%, and the total - phosphorus removal rate reaches more than 85%. During the non - overflow period, the treatment effect is more remarkable, the COD removal rate can reach more than 90%, the total - nitrogen removal rate reaches more than 85%, and the total - phosphorus removal rate reaches more than 90%.

[0075] The present invention is a new process and method for treating river - overflow - outlet water that has been proven by engineering practice applications, is very low - carbon and energy - saving, long - term efficient, and ecologically safe, and has a very broad application prospect.

[0076] As described above, it is only the specific implementation manner of the invention, but the protection scope of the invention is not limited thereto. Those skilled in this field should understand that the invention includes but is not limited to the content described in the drawings and the above - mentioned specific implementation manner. Any modification that does not deviate from the functional and structural principles of the invention will be included in the scope of the claims.

Claims

1. A treatment process for river overflow outlets combining physical adsorption and biological denitrification, characterized in that, An inlet basin, a first-stage filtration and oxidation zone, a second-stage filtration and oxidation zone, a third-stage filtration and oxidation zone, and a fourth-stage filtration zone are sequentially arranged from upstream to downstream along the water flow direction of the river channel. The first-stage filtration and oxidation zone is provided with a first-stage packing bin and a first-stage contact oxidation bin. The second-stage filtration and oxidation zone is provided with a second-stage packing bin and a second-stage contact oxidation bin. The third-stage filtration and oxidation zone is provided with a third-stage packing bin and a third-stage contact oxidation bin; The inlet basin pre-treats the influent water; The packing bins in the first-stage filtration and oxidation zone, the second-stage filtration and oxidation zone, and the third-stage filtration and oxidation zone play a dual role of physical filtration and chemical adsorption on the influent water, thereby removing impurities and harmful components in the influent water. Biological packing is provided in the contact oxidation bin and an aeration pipe is provided at the bottom for aeration, and microorganisms are used to biodegrade organic matter and ammonia nitrogen in an aerobic environment; The packing bins in the first-stage filtration and oxidation zone, the second-stage filtration and oxidation zone, and the third-stage filtration and oxidation zone are provided with a phosphorus-removing ceramsite packing layer; An activated carbon packing layer is filled in the fourth-stage filtration zone for further purification of the effluent water.

2. The river channel overflow outlet treatment process according to claim 1, characterized in that, Floating aquatic plants are provided in the inlet basin for initially removing some pollutants in the influent water.

3. The river channel overflow outlet treatment process according to claim 1, characterized in that, The inlet basin is provided with a grille for intercepting large particle suspended matters in the influent water.

4. The river channel overflow outlet treatment process according to claim 1, characterized in that Multiple packing bins and contact oxidation bins in the first-stage filtration and oxidation zone, the second-stage filtration and oxidation zone, and the third-stage filtration and oxidation zone are arranged alternately.

5. The river channel overflow outlet treatment process according to claim 4, characterized in that, The packing bins in the first-stage filtration and oxidation zone, the second-stage filtration and oxidation zone, and the third-stage filtration and oxidation zone are provided with a four-layer structure, which are a volcanic stone layer, a double-layer phosphorus-removing ceramsite and a sunflower seed slice layer from bottom to top.

6. The river channel overflow outlet treatment process according to claim 1, wherein The activated carbon packing layer is located in the middle and lower part of the fourth-stage filtration zone, and a sunflower seed slice layer is provided in the upper part of the fourth-stage filtration zone.

7. The river channel overflow outlet treatment process according to claim 1, characterized in that The first-stage filtration and oxidation zone, the second-stage filtration and oxidation zone, the third-stage filtration and oxidation zone, and the fourth-stage filtration zone are all independent standard module structures.

8. The river channel overflow outlet treatment process according to claim 1, characterized in that The inlet basin is an independent standard module structure and is provided with a water-facing surface inclined at 45°.

9. The river channel overflow outlet treatment process according to claim 1, characterized in that, Air-blowing perforated pipes are provided in the packing bins in the first-stage filtration and oxidation zone, the second-stage filtration and oxidation zone, and the third-stage filtration and oxidation zone and in the fourth-stage filtration zone, and compressed air is regularly introduced through the air-blowing perforated pipes to backwash the packing.

10. The river channel overflow outlet treatment process according to claim 9, characterized in that, An effluent trough is provided between the third-stage filtration and oxidation zone and the fourth-stage filtration zone, and a spraying device is arranged at the top of the effluent trough for eliminating residual floating foam on the effluent water.

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