CN220619984U - Reclamation system to improve nitrate removal efficiency - Google Patents

Abstract

The utility model discloses a sea-filling land-making system for improving nitrate removal efficiency, which sequentially comprises an original water-bearing layer, a cushion layer and a hydraulic reclamation area along the flowing direction of groundwater; quartz sand walls for providing growth space for denitrifying bacteria and filtering groundwater are arranged in the cushion layer at intervals along the transverse direction; the hydraulic reclamation area comprises a impervious layer for reducing the flow rate of water flow and prolonging the residence time of nitrate in the aquifer. The quartz sand wall transversely distributed in the utility model has a huge specific surface area, provides good absorption and growth environment for microorganisms, and the formed microbial film can effectively intercept and remove nitrate from inland, and the longitudinally arranged concrete impermeable layer reduces the flow rate of groundwater, increases the residence time of nitrate and improves the denitrification efficiency.

Description

Reclamation system to improve nitrate removal efficiency

Technical field

The utility model relates to a sea reclamation and land creation system, in particular to a sea reclamation and land creation system that improves nitrate removal efficiency.

Background technique

Sand blowing and reclamation is to create land by blowing sand to the target area, filling the area that was originally flooded by seawater into sand, and then compacting and solidifying it. However, this method does not specifically consider the specific permeability coefficient of the reclamation area, and the permeability coefficient of coastal aquifers will have a great impact on the migration of solutes such as nutrients and pollutants.

At the same time, agriculture in coastal areas discharges large amounts of nitrogen into water bodies, and pollutants represented by nitrates enter groundwater flow through rainfall infiltration, river discharge, etc., causing adverse effects on coastal ecology. Nitrate substances cause great damage to the groundwater environment and have far-reaching impacts. They have gradually become an important issue in water resources at this stage.

The hydrogeological conditions of coastal aquifers are complex, and it is difficult to study the transport of reactive solutes. There are even fewer studies on the biochemical reactions of coastal aquifers under the influence of human activities. Therefore, how to increase nitrates during land reclamation Removal efficiency is still one of the difficult problems that researchers need to overcome.

Utility model content

Purpose of the utility model: The purpose of the utility model is to provide a land reclamation system with good denitrification effect and improved nitrate removal efficiency.

Technical solution: The sea reclamation and land reclamation system for improving nitrate removal efficiency described in this utility model sequentially includes an original aquifer, a cushion layer, and a blowing and reclamation area along the direction of groundwater flow; the cushion layer is provided with transverse intervals for providing reaction Quartz sand walls provide growth space for nitrifying bacteria and filter groundwater; the blow-fill area includes an anti-seepage layer used to reduce the flow rate of water and prolong the residence time of nitrates in the aquifer.

Wherein, the width of the quartz sand wall is 1.5-2m; the lateral spacing between two adjacent quartz sand walls is 5-10m. The intervals between the quartz sand walls are such that they can play a sufficient filtering role in the direction of groundwater flow. At the same time, the appropriate width can not only ensure the growth of microorganisms, but also ensure that the cost is not too high.

Wherein, the blowing and filling area also includes a sand layer, and the anti-seepage layer is arranged at longitudinal intervals along the sand layer.

Among them, the height of the anti-seepage layer is 0.6~1.2m; the longitudinal spacing between two adjacent anti-seepage layers is 2~2.5m. The height of the concrete anti-seepage layer ensures that it has appropriate strength and elastic modulus, effectively preventing cracking during later use. The anti-seepage layer spacing is set based on the flow characteristics and tidal amplitude of the aquifer sea boundary to ensure fresh water near the low tide level. Anti-seepage layers are installed at the discharge outlet and at the seawater circulation inlet near high tide.

Wherein, the cushion layer includes pebbles, and carbon particles are dispersed between the pebbles; the cushion layer uses artificial pebbles with a particle size of no more than 0.1m. The thickness of the cushion layer is 0.5-1m.

Wherein, the permeability coefficient of the reclamation area is smaller than the original aquifer, which is used to increase the migration time of terrestrial nitrate substances.

Wherein, the anti-seepage layer is a concrete pouring layer; high-pressure air is used to spray cement slurry or cement mortar onto the sand surface to form a uniform and dense concrete pouring layer.

Beneficial effects: Compared with the existing technology, this utility model achieves the following significant effects:

(1) The cushion layer of the present utility model and its horizontally arranged quartz sand wall, in cooperation with the vertically arranged anti-seepage layer, ensure that the electron donor required for denitrification is sufficient and at the same time increase the time of nitrification and denitrification. Achieve good denitrification effect and improve nitrate removal efficiency; (2) The intervals between quartz sand walls are such that they can play a sufficient filtering role in the direction of groundwater flow, and the appropriate width can ensure the growth of microorganisms. It can also ensure that the cost will not be too high; (3) The height of the concrete anti-seepage layer ensures that it has appropriate strength and elastic modulus, effectively preventing it from cracking in later use, and is set according to the flow characteristics and tidal amplitude of the aquifer sea boundary. The anti-seepage layer spacing ensures that there are anti-seepage layers at the fresh water outlet near the low tide level and the seawater circulation inlet near the high tide level; (4) The cushion layer between the original aquifer and the blow-filled area can play a role Good connection and fixation effect; (5) The organic carbon in the cushion can increase the respiration of heterotrophic bacteria, consume more oxygen, and provide a favorable environment for denitrification. At the same time, the organic carbon provides enough for denitrification. Electron donor; (6) Low permeability reclamation area increases solute migration time to avoid poor nitrogen removal effect caused by insufficient reaction time.

Description of the drawings

Figure 1 is a schematic structural diagram of the utility model;

Figure 2 is a schematic structural diagram of solute migration after land reclamation.

Detailed ways

The technical solution of the present utility model will be further described below in conjunction with the accompanying drawings of the description.

As shown in Figure 1, the utility model provides a land reclamation system that improves nitrate removal efficiency. It includes an original aquifer 1, a cushion layer 2, and a reclamation area 3 along the direction of groundwater flow.

The cushion layer 2 includes an artificial pebble layer 201 and organic carbon particles 202 filled in the artificial pebble layer. A plurality of quartz sand walls 203 are arranged at transverse intervals in the artificial pebble layer 201. The width of the quartz sand wall is 1.5~2m; the lateral spacing between two adjacent quartz sand walls is 5~10m.

The cushion layer uses artificial pebbles 201 with a particle size not larger than 0.1m. The gaps between the pebbles are filled with organic carbon particles 202. The thickness of the cushion layer is 0.5-1m. Organic carbon particles provide electron donors for denitrification. The low-permeability reclamation area ensures sufficient time for the reaction, and the cost of reclamation and land reclamation is small, so the economy is good. First, small-size artificial pebbles 201 are laid above the original aquifer 1 to support and diffuse stress. Organic carbon particles 202 are filled between the artificial pebbles. The denitrifying bacteria are heterotrophic facultative anaerobic bacteria that use NOx-N as the electron acceptor and organic carbon as the electron donor under anaerobic conditions. Add quartz sand to the cushion. Quartz sand has a large specific surface area, which is conducive to the growth of denitrifying bacteria. Quartz sand can also filter groundwater. Since the flow direction of groundwater here is almost horizontal, the quartz sand walls are distributed vertically, which not only plays a good filtering role in the flow of groundwater, but also saves materials. Quartz sand walls provide growth space for denitrifying bacteria and filter groundwater.

The blowing and filling area 3 includes a sand layer 302 and an anti-seepage layer 301 distributed longitudinally along the sand layer in the sand layer. The anti-seepage layer can reduce the water flow rate and make the nitrate stay in the aquifer for a longer period of time, thus increasing the reaction rate. Nitrification. The height of the anti-seepage layer is 0.6~1.2m; the longitudinal spacing between two adjacent anti-seepage layers is 2~2.5m. The preparation process of the blowing and reclamation area is: the blowing and reclamation area 3 is a low permeability area. Sand dredgers can be used to blow the sand and water from the local seabed into the target circle, piling ships can be used to drive piles to fix the edges, and tamping machines can be used to compact them multiple times. The sand ship transports the sand to the designated reclamation area, lays a layer of sand and then adds an anti-seepage layer. The permeability coefficient of the reclamation area 3 is smaller than that of the original aquifer 1.

work process:

As shown in Figure 2, under the action of the ocean driving force tide 10, the seawater intrusion is divided into an upper saltwater plume 4 and a lower saltwater wedge 5. The upper saltwater plume 4 is also called the intertidal zone, which is an area with strong biochemical activities. area, between the upper salt water plume 4 and the lower salt water wedge 5 is the fresh water discharge channel. Tidal fluctuations will bring dissolved organic carbon and oxygen into the upper salt water plume, and the dissolved organic carbon and oxygen will respire, consuming oxygen. The microbial denitrification process is the process of reducing nitrate and nitrite into gaseous nitrogen 8 under anaerobic or low-oxygen conditions. Under aerobic conditions, the growth rate of denitrifying bacteria is slow, and the organic carbon added in the cushion 2 The supply of 202 is conducive to the consumption of oxygen and provides favorable anaerobic conditions for denitrifying bacteria. The quartz sand wall 203 is composed of fine quartz sand particles and has a huge specific surface area, which can provide a good adsorption and growth environment for microorganisms. The resulting microbial film can effectively intercept and remove nitrates coming from the inland 7 . Nitrate 7 continues to move seaward to the reclamation area, carried by underground fresh water. At this time, the groundwater flow direction changes from horizontal to obliquely upward and moves toward the seawater-aquifer boundary. The vertically arranged concrete anti-seepage layer 301 reduces the flow rate of groundwater. The retention time of nitrate is increased and the denitrification efficiency is improved.

Claims (8)

1. A land reclamation system that improves nitrate removal efficiency, characterized in that it includes an original aquifer (1), a cushion (2), and a reclamation area (3) along the direction of groundwater flow; the cushion (3) 2) Quartz sand walls (203) are arranged at horizontal intervals along the inner surface to provide growth space for denitrifying bacteria and filter groundwater; the blowing and filling area (3) includes a wall for reducing the flow rate of water and extending the residence time of nitrate in the aquifer. Anti-seepage layer (301). 2. The sea reclamation system for improving nitrate removal efficiency according to claim 1, characterized in that the width of the quartz sand wall (203) is 1.5~2 m; two adjacent quartz sand walls (203) The lateral spacing is 5~10 m. 3. The reclamation system for improving nitrate removal efficiency according to claim 1, characterized in that the reclamation area further includes a sand layer (302), and the anti-seepage layer (301) is along the sand layer (302). ) Vertical spacing setting. 4. The sea reclamation system for improving nitrate removal efficiency according to claim 1, characterized in that the height of the anti-seepage layer (301) is 0.6~1.2 m; two adjacent anti-seepage layers (301) The longitudinal spacing between them is 2~2.5 m. 5. The sea reclamation system for improving nitrate removal efficiency according to claim 1, characterized in that the thickness of the cushion (2) is 0.5~1 m. 6. The reclamation system for improving nitrate removal efficiency according to claim 1, characterized in that the permeability coefficient of the reclamation area (3) is smaller than the permeability coefficient of the original aquifer (1), which is used to increase land sources. Migration time of nitrate species. 7. The sea reclamation system for improving nitrate removal efficiency according to claim 1, characterized in that the anti-seepage layer (301) is a concrete pouring layer. 8. The sea reclamation system for improving nitrate removal efficiency according to claim 7, characterized in that the concrete pouring layer is formed by spraying cement slurry or cement mortar onto the sand surface with high-pressure air.