CN108409027A - A kind of biological delaying basin for strengthening road Initial Runoff denitrogenation dephosphorizing process - Google Patents

Abstract

The invention provides a bioretention pond for strengthening the denitrification and phosphorus removal process of the initial runoff of the road, which is sequentially laid with a soil covering layer, an upper layer of mixed filler layer, a lower layer of mixed filler layer, a crushed stone filter layer and a pebble supporting layer. , the lower mixed packing layer is a low-permeability mixed packing, which is formed by mixing river sand, aluminum sludge and wood chips, the upper mixed packing layer is a high-permeable mixed packing, and the upper mixed packing layer is provided with A plurality of ventilation pipes, one end of the ventilation pipe extends into the upper mixed packing layer, and the other end stretches out from the top of the bioretention tank to communicate with the air, and the plurality of ventilation pipes are communicated through pipelines. The novel bioretention tank of the present invention can It is fully combined with the greening and landscape construction of urban roads, parks, living areas and other areas to achieve the double effect of purification and greening.

Description

A bioretention pond for strengthening the process of denitrification and phosphorus removal of initial road runoff

technical field

The invention relates to the field of environmental protection, in particular to a bioretention pond for strengthening the denitrification and dephosphorization process of initial road runoff.

Background technique

my country is currently in the stage of rapid urbanization, which has brought enormous pressure and challenges to the urban water environment and caused a series of environmental problems. Urban non-point source pollution refers to the environmental problems caused by rainwater and runoff scouring the urban ground under the condition of precipitation, causing pollutants to enter the receiving water body. Due to the strong human activities in the city and the high proportion of impermeable land area, the rainfall runoff is fierce, the water volume is large, and the water quality is poor. The major urban non-point source pollutants are COD, SS, TP and TN. These pollutants enter surface water bodies with rainfall, especially in the initial rainfall. The removal of these pollutants is of great significance to the protection of urban water environment and the rational and efficient use of water resources. At the same time, in order to improve urban water security and water ecological environment, my country is currently constructing sponge cities. Sponge city is a new generation of urban stormwater management concept. It refers to the city's good "elasticity" in adapting to environmental changes and responding to natural disasters caused by rainwater. It can also be called "water elastic city". The international general term is "low-impact development stormwater system construction". When it rains, it absorbs, stores, infiltrates, and purifies water, and "releases" the stored water for use when needed. Building a sponge city requires a "sponge body". The urban "sponge body" includes not only water systems such as rivers, lakes, and ponds, but also urban supporting facilities such as green spaces, gardens, and permeable pavements. Rainwater infiltrates, stores, purifies, and reuses through these "sponge bodies", and finally the remaining part of the runoff is discharged through pipe networks and pumping stations, which can effectively improve the standard of urban drainage systems and reduce the pressure of urban waterlogging. Therefore, to meet the requirements of sponge city construction, in order to ensure the water quality of rivers, lakes, ponds or reservoirs, it is also required to intercept and remove non-point source pollutants in rainwater.

Urban green belts and landscape areas have a buffering effect on urban rainfall runoff, intercept and remove non-point source pollutants, and play an important role in protecting urban water ecology and water environment. At present, in the construction of urban green belts or urban landscape areas, there are still shortcomings of single function and unreasonable structure settings. In particular, there is no reasonable and targeted structural design for the removal mechanism of non-point source pollutants and other pollutants. And the interception and removal effect is not good.

Bioretention facilities can effectively remove a variety of pollutants in stormwater runoff, including nitrogen compounds. The organic nitrogen and ammonia nitrogen in the influent water of the facility are easily removed by adsorption or interception by the medium during the infiltration process. The adsorbed organic nitrogen and ammonia nitrogen are converted into nitrate nitrogen through ammonification and nitrification under the action of oxygen during the dry period between two rainfall events. Nitrate nitrogen is only removed in the form of _N2 by denitrification under the condition of anoxic and abundant carbon source. In order to ensure the moisture content of the facility and provide nutrients for plant growth, traditional bioretention facilities add a certain amount of compost to the medium of the filler layer, which can provide carbon sources for denitrification. However, the medium in traditional bioretention facilities is in an aerobic state during the intermittent period of rainfall, which usually cannot meet the anoxic conditions required for denitrification. Because the medium cannot effectively adsorb negatively charged nitrate, the concentration of nitrate in the effluent of the bioretention facility is often higher than that in the influent, especially when the influent is relatively high in ammonia nitrogen and organic nitrogen. In order to solve the above problems, the disclosed invention patent document proposes to increase the position of the water outlet and create a flooded area to create an anaerobic environment conducive to denitrification in the lower part of the facility. The total annual runoff control rate of the facility is not satisfied, and the removal effect of nitrate nitrogen is not satisfactory

The ideal method should be that this method can freely select green plants according to the requirements of different green belts and landscape area construction, and set up a reasonable bioretention tank structure according to the requirements of the biochemical process of nitrogen and phosphorus removal, and at the same time can realize The rapid removal of water does not cause road surface water, and more importantly, the efficient removal of nitrogen and phosphorus in water can be achieved to avoid eutrophication of water bodies.

Contents of the invention

Aiming at the deficiencies in the prior art, the invention provides a bioretention pond for strengthening the denitrification and dephosphorization process of initial road runoff.

The present invention achieves the above-mentioned technical purpose through the following technical means.

A bioretention pond for strengthening the denitrification and phosphorus removal process of the initial runoff of the road. From top to bottom, a soil cover layer, an upper layer of mixed filler layer, a lower layer of mixed filler layer, a crushed stone filter layer and a pebble support layer are successively laid. There are multiple drainage pipes in the supporting layer, one end of the drainage pipe is located in the pebble supporting layer, and the other end of the drainage pipe extends out of the bioretention tank to discharge or transport the treated rainwater to the next treatment in time. facilities, the lower mixed packing layer is a low-permeability mixed packing, which is made of river sand, aluminum sludge and wood chips, the upper mixed packing layer is a high-permeable mixed packing, and the upper mixed packing layer is set There are multiple ventilation pipes. One end of the ventilation pipe extends into the upper mixed packing layer, and the other end protrudes from the top of the bioretention tank to communicate with the air. The multiple ventilation pipes are connected through pipelines, and there are multiple ventilation pipes. The air outlet, the upper mixed packing layer has a large particle size and high permeability. At the same time, the ventilation pipe is set to make the upper mixed packing in an aerobic state, and the lower mixed packing layer has a small particle size. The alternation of dry periods gradually forms an aerobic and anoxic state from top to bottom, and microorganisms gradually form a stable community, so that the nitrification and denitrification processes can proceed smoothly.

Preferably, the volume ratio of river sand, aluminum sludge and wood chips in the lower layer of mixed filler is 75-85:10-15:5-10, which has the best effect on removing pollutants.

Preferably, the upper mixed packing layer is formed by mixing river sand, slag and quartz sand.

Preferably, the volume ratio of river sand, slag and quartz sand in the upper mixed packing layer is 75-85:5-10:10-15, so as to achieve efficient removal of pollutants while ensuring low cost.

Preferably, the pebble supporting layer has a particle size of 10-20mm and a height of 200mm.

Preferably, the crushed stones in the crushed stone filter layer have a particle size of 8-10mm and a thickness of 150-20mm, and filter the finely divided filter material lost in the packing layer to prevent the finely crushed packing from losing with the water body and causing blockage to the lower drainage system.

Preferably, plants are planted in the soil covering layer, and the plants are one or more of flowers, grasses or shrubs. The plant species should adapt to the local climate, and achieve the effect of beautifying the environment while purifying the water.

Preferably, the aluminum sludge in the lower mixed filler is tailings from waterworks. Because the phosphorus content in the tailings from sewage plants is too high, there is leaching phenomenon, so it is not suitable to use sludge from sewage plants.

Preferably, a strainer is provided at one end port of the drainpipe located in the pebble supporting layer, so as to reduce the risk of clogging of the drainpipe.

Preferably, an overflow pipe is also included, one end of the overflow pipe communicates with the drainage pipe in the pebble supporting layer, and the other end extends into the aquifer above the soil cover layer, and is the highest with the aquifer. flat.

Beneficial effects of the present invention:

1. The present invention adopts the method of adding a ventilation pipe to the upper low-permeability material to ensure that the runoff can infiltrate quickly during the rainy season and reduce the risk of urban waterlogging. At the same time, during the drying period and the water distribution period, the upper layer of the system can maintain a good aerobic environment, which is conducive to the nitrification reaction, so as to achieve the purpose of removing ammonia nitrogen. The lower layer is equipped with low-permeability materials, and wood chips are added as organic matter to create the conditions required for the denitrification process and achieve the reduction of nitrate nitrogen.

2. The lower filler of the present invention uses aluminum sludge as the modifier. The material has a well-developed pore structure and a high specific surface area, so it has a relatively large adsorption capacity for phosphorus. Secondly, the aluminum sludge is mainly amorphous Non-crystalline structure, containing a large amount of metal ions or oxides such as aluminum, iron, calcium, etc. These ions have strong adsorption properties for phosphate, and can undergo complexation reactions with phosphate to form stable metal ion phosphate complexes. So as to achieve the purpose of phosphorus removal.

3. Aluminum sludge is a kind of solid waste in waterworks. Sanitary landfill has been its main treatment method for a long time. However, this invention uses aluminum sludge as an additive to realize the resource utilization of solid waste.

4. The present invention efficiently intercepts pollutants such as COD and SS in the initial runoff of roads, and at the same time realizes an efficient nitrogen and phosphorus removal process. At the same time, it can be fully combined with the greening and landscape construction of urban roads, parks, living areas and other areas to achieve the dual effects of greening and rainwater purification.

Description of drawings

Fig. 1 is a structural schematic diagram of a bioretention pond for strengthening the denitrification and phosphorus removal process of initial road runoff according to the present invention.

In the figure: 1. Drainage pipe; 2. Ventilation pipe; 3. Aquifer; 4. Soil cover layer; 5. Upper layer of mixed filler layer; 6. Lower layer of mixed filler layer; Layer; 9. Overflow pipe

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited thereto.

As shown in Fig. 1, a kind of bioretention pond of the present invention strengthens the denitrification and dephosphorization process of the initial stage runoff of the road, and from top to bottom, a soil cover layer 4, an upper layer of mixed filler layer 5, and a lower layer of mixed filler layer 6 are successively laid. , gravel filter layer 7 and pebble supporting layer 8, the particle diameter of pebble in described pebble supporting layer 8 is 10～20mm, and height is 200mm, is provided with two drainage pipes 1 in pebble supporting layer 8, and described drainage The end of the pipe 1 extends out of the bioretention tank to discharge or transport the treated rainwater to the next treatment facility in a timely manner. The port of the drain pipe 1 located in the pebble supporting layer 8 is provided with a filter to reduce the blockage of the drain pipe 1 risks of. The lower mixed filler layer 6 is a low-permeability mixed filler, which is formed by mixing river sand, aluminum sludge and wood chips in a volume ratio of 75-85:10-15:5-10. The upper mixed filler layer 5 It is a high-permeability mixed filler, which is composed of river sand, slag and quartz sand in a volume ratio of 75-85:5-10:10-15. The upper mixed filler layer 5 is provided with a plurality of ventilation pipes 2, One end of the ventilation pipe 2 extends into the upper layer of mixed packing layer 5, and the other end stretches out from the top of the bioretention tank to communicate with the air, and a plurality of said ventilation pipes (2) are communicated through, and the particle size of the upper layer of mixed packing layer 5 is large. , the permeability is high, and the air pipe is set at the same time, so that the upper layer of mixed packing layer 5 can be in an aerobic state, and the particle size of the lower layer of mixed packing layer 6 is small. Under the condition of aerobic and anoxic conditions, microorganisms gradually form a stable community, so that the process of nitrification and denitrification can proceed smoothly. The gravel in the gravel filter layer 7 has a particle size of 8-10mm and a thickness of 150-20mm, and filters the finely crushed filter material lost in the packing layer to prevent the finely crushed packing from losing with the water body and causing blockage to the lower drainage system.

Embodiment one

Excavate the soil at a certain depth, lay a pebble support layer 8 on the bottom layer, the laying height is 200mm, the pebble particle size is 10-20mm, and two drainage pipes 1 with a diameter of 100mm are horizontally arranged in the pebble support layer 8, The drainage pipe 1 is used to discharge or transport the treated rainwater to the next treatment facility in a timely manner, and then lay a layer of gravel filter layer 7 with a filling thickness of 150mm and a particle size of 8-10mm; on the gravel filter layer 7 It is filled with low-permeability mixed filler mixed with river sand, aluminum sludge and sawdust, with a height of 500mm. River sand, aluminum sludge, and wood chips are configured in a volume ratio of 85:10:5.

On the lower mixed packing layer 6 , a layer of large particle size mixed with river sand, slag and quartz sand, high permeability mixed packing, and an upper mixed packing layer 5 with a height of 300 mm are laid. The river sand, slag and quartz sand are configured according to the volume ratio of 85:5:10, and a plurality of ventilation pipes 2 are arranged in this layer. The permeability and oxygen content of the entire upper mixed filler can be recovered during the drying period.

A soil cover layer with a thickness of 150mm is laid on the upper mixed filler layer, and irises are planted on this layer to achieve the function of beautifying the environment while purifying water.

Embodiment two

Excavate the soil at a certain depth, lay a pebble support layer 8 on the bottom layer, the laying height is 200mm, the pebble particle size is 10-20mm, two drainage pipes 1 with a diameter of 100mm are horizontally arranged in the layer pebble support layer 8, The drainage pipe 1 is used to discharge or transport the treated rainwater to the next treatment facility in a timely manner, and then lay a layer of crushed stone filter layer 7 with a filling thickness of 150mm and a crushed stone particle size of 8-10mm;

The gravel filter layer 7 is filled with low-permeability mixed packing made of river sand, aluminum sludge and wood chips, with a height of 600mm. River sand, aluminum sludge, and wood chips are configured in a volume ratio of 75:15:10.

On the lower mixed packing layer, lay a layer of large particle size and high permeability mixed packing made of river sand, slag and quartz sand, with a height of 400mm. The river sand, slag and quartz sand are configured according to the volume ratio of 75:10:15, and the ventilation pipe 2 is set in this layer. The permeability and oxygen content of the mixed filler can be recovered during the drying period.

A soil cover layer with a thickness of 150mm is laid on the upper layer of mixed filler layer, and irises are planted on this layer to achieve the function of beautifying the environment while purifying water.

Carry out denitrification and dephosphorization effect detection to embodiment one and implementation two, the result is: can effectively remove more than 90% of ammonia nitrogen and TSS in the initial runoff, and more than 85% of total phosphorus, reach more than 80% to COD retention rate, simultaneously The removal rate of nitrate nitrogen reaches more than 60%, and the removal effect is stable.

The described embodiment is a preferred implementation of the present invention, but the present invention is not limited to the above-mentioned implementation, without departing from the essence of the present invention, any obvious improvement, replacement or modification that those skilled in the art can make Modifications all belong to the protection scope of the present invention.

Claims (10)

1. A bioretention pond for strengthening the denitrification and dephosphorization process of the initial runoff of the road is characterized in that: from top to bottom, a soil cover layer (4), an upper layer of mixed filler layer (5), a lower layer of mixed filler layer (6 ), a gravel filter layer (7) and a pebble supporting layer (8), the pebble supporting layer (8) is provided with a plurality of drainage pipes (1), and one end of the drainage pipe (1) is located at the pebble bearing In the support layer (8), the other end of the drainage pipe (1) protrudes from the bioretention tank, and the lower mixed packing layer (6) is a low-permeability mixed packing made of river sand, aluminum sludge and wood chips , the upper mixed packing layer (5) is a high-permeability mixed packing, the upper mixed packing layer (5) is provided with a plurality of air pipes (2), and one end of the air pipe (2) extends into the upper layer In the mixed packing layer (5), the other end communicates with the air, and a plurality of said ventilation pipes (2) are communicated through pipelines, the upper mixed packing layer (5) constitutes an aerobic zone, and the lower mixed packing layer ( 6) Form an anoxic zone. 2. A kind of bioretention pond for strengthening the denitrification and dephosphorization process of initial stage runoff of road according to claim 1, it is characterized in that: the volume of river sand, aluminum sludge and wood chips in the mixed filler (6) of the lower layer The ratio is 75-85:10-15:5-10. 3. The bioretention pond for strengthening the denitrification and phosphorus removal process of the initial runoff of the road according to claim 1, characterized in that: the upper mixed filler layer (5) is formed by mixing river sand, slag and quartz sand. 4. A kind of bioretention pond for strengthening the denitrification and dephosphorization process of initial stage runoff of road according to claim 3, it is characterized in that: the volume ratio of river sand, slag and quartz sand in the mixed packing layer (5) of the upper layer 75～85:5～10:10～15. 5. A bioretention pond for strengthening the denitrification and phosphorus removal process of the initial runoff of the road according to claim 1, characterized in that: the pebbles in the pebble support layer (8) have a particle size of 10-20mm and a height of 200mm . 6. A kind of bioretention pond for strengthening the denitrification and dephosphorization process of road initial runoff according to claim 1, characterized in that: the gravel in the gravel filter layer (7) has a particle diameter of 8 to 10 mm and a thickness of 150-20mm. 7. A kind of bioretention pond for strengthening the denitrification and dephosphorization process of road initial runoff according to claim 1, characterized in that: plant plants in the soil cover layer (4), and the plants are flowers, grasses or One or more types of shrubs. 8. A bioretention pond for strengthening the denitrification and phosphorus removal process of initial runoff of roads according to claim 1, characterized in that: the aluminum sludge in the lower mixed filler (6) is the tailing sludge of a waterworks. 9. A kind of bioretention pond for strengthening the denitrification and dephosphorization process of the initial runoff of the road according to claim 1, characterized in that: the drainpipe (1) is located at one end port of the pebble supporting layer (8) There is a filter. 10. A kind of bioretention pond for strengthening the denitrification and dephosphorization process of road initial runoff according to claim 1, characterized in that: it also includes an overflow pipe (9), and one end of the overflow pipe (9) is connected with pebbles The drainage pipe (1) in the supporting layer (8) is connected, and the other end extends into the water storage layer (3) above the soil covering layer (4).