阅读说明：本技术 一种用于强化脱氮的湿地系统及其处理污水的方法 (Wetland system for enhanced denitrification and sewage treatment method thereof ) 是由 陆轶峰 杨琴 陈倩 高思雨 李博 马兰 于 2021-07-16 设计创作，主要内容包括：本发明公开了一种用于强化脱氮的湿地系统及其处理污水的方法,湿地系统包括沿水流方向依次设置的表流湿地、自然湿地和潜流湿地；潜流湿地和自然湿地之间还设置有回流装置,旱季时,通过回流装置可使潜流湿地的出水回流至自然湿地；潜流湿地、自然湿地和表流湿地之间还设置有倒流装置,雨季时,通过倒流装置可使雨季进水依次通过潜流湿地、自然湿地和表流湿地。本发明针对旱季、雨季污水的不同特点,通过改变湿地的水流路径,可充分发挥湿地的净化功能,加强脱氮效果,从而降低湿地出水污染物的浓度,减轻湿地出水入湖的污染负荷。(The invention discloses a wetland system for enhanced denitrification and a sewage treatment method thereof, wherein the wetland system comprises a surface flow wetland, a natural wetland and an undercurrent wetland which are sequentially arranged along the water flow direction; a reflux device is arranged between the subsurface flow wetland and the natural wetland, and the effluent of the subsurface flow wetland can be refluxed to the natural wetland through the reflux device in dry seasons; and a backflow device is arranged among the subsurface flow wetland, the natural wetland and the surface flow wetland, and the inflow water in rainy season can sequentially pass through the subsurface flow wetland, the natural wetland and the surface flow wetland through the backflow device in rainy season. Aiming at different characteristics of sewage in dry seasons and rainy seasons, the invention can fully exert the purification function of the wetland and enhance the denitrification effect by changing the water flow path of the wetland, thereby reducing the concentration of pollutants in effluent of the wetland and lightening the pollution load of effluent of the wetland entering the lake.)

1. The wetland system for enhancing denitrification is characterized by comprising a surface flow wetland, a natural wetland and an undercurrent wetland which are sequentially arranged along the water flow direction; a backflow device is arranged between the subsurface flow wetland and the natural wetland, the backflow device comprises a backflow pipe and a backflow pump, and the outflow water of the dry season subsurface flow wetland can flow back to the natural wetland through the backflow device; the subsurface flow wetland, the natural wetland and the surface flow wetland are also provided with a backflow device therebetween, the backflow device comprises a flow guide pipe and a flow guide pump, and water can be fed in rainy seasons through the subsurface flow wetland, the natural wetland and the surface flow wetland by the backflow device.

2. The wetland system for enhanced nitrogen removal according to claim 1, wherein the bottoms of the surface flow wetland and the subsurface flow wetland are tamped by plain soil, and an impermeable layer is artificially laid above the plain soil; the anti-seepage layer top of undercurrent wetland still is provided with the packing layer, the packing layer from supreme down constitute by drainage blanket, filter material layer and planting soil layer in proper order, drainage blanket adopt the cobble that the particle diameter is 30 ~ 80mm to lay, the filter material layer adopt the zeolite that the particle diameter is 15 ~ 30mm to lay, planting soil layer adopt planting soil to cover.

3. The wetland system for enhanced nitrogen removal according to claim 2, wherein the thickness of the drainage layer is 200 mm; the thickness of the filter material layer is 700 mm; the thickness of the planting soil layer is 200 mm.

4. The wetland system for enhanced nitrogen removal according to claim 2, wherein the compacted density of the plain soil>95 percent, and the permeability coefficient of the impermeable layer is less than or equal to 10^-8cm/s。

5. The wetland system for enhanced nitrogen removal according to claim 1, wherein the surface wetland, the natural wetland and the subsurface wetland have a water depth of 0.3-0.5m with the surface wetland ground as a relative elevation zero point.

6. The wetland system for enhanced nitrogen removal according to claim 1, wherein aquatic plants are planted in the surface flow wetland, the natural wetland and the subsurface flow wetland.

7. The wetland system for enhanced nitrogen removal according to claim 6, wherein the aquatic plant is one or more of Scirpus tabernaemontani, Typha orientalis and Phragmites communisThe planting density of the aquatic plants is 2-10 clusters/m in any combination²。

8. A method for treating sewage by using the wetland system for enhanced nitrogen removal of claim 2, which is characterized by comprising the following steps:

(1) refluxing in dry seasons: in dry seasons, the inflow water sequentially passes through the surface flow wetland, the natural wetland and the subsurface flow wetland, and then flows back to the natural wetland through the backflow device; then, by using the raw water as a carbon source, carrying out secondary nitrification and denitrification reactions on nitrate nitrogen and nitrite nitrogen in the effluent in the subsurface wetland so as to enhance the denitrification capability of the wetland, and finally discharging the denitrified water into a receiving water body;

(2) backflow in rainy season: in rainy season, the inflow water is led to the subsurface flow wetland through the backflow device, and the filler of the subsurface flow wetland is utilized to carry out ion exchange and physical adsorption on granular nitrogen and nitrate nitrogen in the inflow water so as to reduce the total nitrogen concentration; then sequentially passing through the natural wetland and the surface flow wetland, further reducing the total nitrogen concentration through plant absorption and microbial degradation in the natural wetland and the surface flow wetland, and finally discharging into a receiving water body.

9. The method for treating sewage by using the wetland system for enhanced nitrogen removal as recited in claim 8, wherein the reflux ratio in the dry season reflux method is 1: 1-3.

Technical Field

The invention belongs to the technical field of sewage treatment, and particularly relates to a wetland system for enhanced denitrification and a sewage treatment method thereof.

Background

The wetland is a comprehensive ecological system, and the wetland utilizes the principles of species symbiosis, substance cycle regeneration, structure and function coordination in the ecological system, fully exerts the production potential of the wetland ecological system on the premise of promoting the virtuous cycle of pollutants in water, greatly reduces the pollutants in the water, obtains the best benefits of water environment and water ecology, and effectively reduces the pollution load of the received surface water body (lakes or rivers). However, the situation that the wetland is not full in dry seasons and not full in rainy seasons due to the obvious difference of the water inflow amount of the wetland in dry and rainy seasons is caused: in dry seasons, the operating water level of the wetland is reduced, the pollution load of inlet water is high, the pollutant is not completely converted within the same hydraulic retention time, and the effluent cannot reach the pollution reduction target; storm runoff is increased in rainy season, the inlet water volume of the wetland is increased, a large amount of overflow is generated in the lakeside wetland, and the impact influence on the surface water body is still caused by the large water volume condition of untreated water body although the pollution load is low. Therefore, how to improve the treatment capacity of the wetland for sewage with different water amounts and pollution loads is one of the main problems faced by the wetland.

Disclosure of Invention

The invention aims to solve the problem that the denitrification efficiency of a traditional wetland system constructed by surface flow wetland, natural wetland and subsurface flow wetland is low, and provides a wetland system for enhancing denitrification and a method for treating sewage by the same, aiming at the large change condition of the hydraulic load and the concentration load of the wetland system in rainy and dry seasons.

The invention is implemented by the following technical scheme:

a wetland system for enhancing denitrification comprises a surface flow wetland, a natural wetland and an undercurrent wetland which are sequentially arranged along the water flow direction; a reflux device is also arranged between the subsurface flow wetland and the natural wetland, the reflux device comprises a reflux pipe and a reflux pump, and the effluent of the subsurface flow wetland can be refluxed to the natural wetland through the reflux device; and a backflow device is also arranged among the subsurface flow wetland, the natural wetland and the surface flow wetland, the backflow device comprises a flow guide pipe and a flow guide pump, and the inflow water in rainy seasons can sequentially pass through the subsurface flow wetland, the natural wetland and the surface flow wetland through the backflow device.

The bottoms of the surface flow wetland and the subsurface flow wetland are tamped by plain soil, and an impermeable layer is artificially laid above the plain soil; a packing layer is also arranged above the anti-seepage layer of the subsurface wetland, the packing layer sequentially consists of a drainage layer, a filter material layer and a planting soil layer from bottom to top, the drainage layer is paved by pebbles with the particle size of 30-80 mm, and the thickness of the drainage layer is 200 mm; the filter material layer is paved by zeolite with the particle size of 15-30 mm, and the thickness of the filter material layer is 700 mm; the planting soil layer is covered by planting soil, and the thickness of the planting soil layer is 200 mm.

Tamped density of the plain soil>95 percent, and the permeability coefficient of the impermeable layer is less than or equal to 10^-8cm/s。

The pollution load of the natural wetland is 9-10% of that of the surface flow wetland; the pollution load of the subsurface flow wetland is 60 percent of that of the surface flow wetland.

The surface flow wetland ground is taken as a relative elevation zero point, and the water depth of the surface flow wetland, the natural wetland and the subsurface flow wetland is 0.3-0.5 m.

Aquatic plants are planted in the surface flow wetland, the natural wetland and the subsurface flow wetland.

The aquatic plant is one or any combination of herba Alii Fistulosi, rhizoma Typhae, and rhizoma Phragmitis, and has planting density of 2-10 clusters/m²。

A method for treating sewage by a wetland system for enhancing denitrification comprises the following steps:

(1) refluxing in dry seasons: in dry seasons, the inlet water flows through the surface flow wetland, the natural wetland and the subsurface flow wetland in sequence, and then the outlet water flows back to the natural wetland through the backflow device; secondly, carrying out secondary nitrification and denitrification reactions on nitrate nitrogen and nitrite nitrogen in the effluent in the subsurface flow wetland by using raw water as a carbon source through the subsurface flow wetland so as to enhance the denitrification capability of the wetland, and finally discharging the denitrified water into a receiving water body;

(2) backflow in rainy season: in rainy season, the inlet water is led to the subsurface flow wetland through the backflow device, and the filler of the subsurface flow wetland is utilized to carry out ion exchange and physical adsorption on granular nitrogen and nitrate nitrogen in the inlet water so as to reduce the total nitrogen concentration; then sequentially passing through the natural wetland and the surface flow wetland, further reducing the total nitrogen concentration through plant absorption and microbial degradation in the natural wetland and the surface flow wetland, and finally discharging into a receiving water body.

The reflux ratio in the dry season reflux method is 1: 1-3.

The principle of the invention is as follows:

in dry seasons, the wetland inlet water amount is small, the water quality is in a high pollution load state, the denitrification reaction of nitrate nitrogen and nitrite nitrogen with higher content in the raw outlet water in the subsurface wetland is performed again by utilizing the backflow, and the high-content carbon source in the inlet water can provide sufficient carbon source for the denitrification reaction, so that the denitrification efficiency of the wetland is improved, meanwhile, the moisture can be supplemented for the wetland, and the ecological water level of each unit is ensured.

In rainy season, the wetland is in a low pollution load state with large inflow water quantity, so that the wetland is required to play a denitrification function in a short hydraulic retention time, the sewage firstly passes through the subsurface flow wetland, the filler is used for carrying out ion exchange and physical adsorption on granular nitrogen and nitrate nitrogen in the sewage, the total nitrogen concentration is greatly reduced, and then the total nitrogen is reduced through plant absorption in the natural wetland and the surface flow wetland and the purification effect of microorganisms, so that the denitrification enhancement is realized.

Compared with the prior art, the invention has the following beneficial effects:

1. aiming at different characteristics of sewage in dry seasons and rainy seasons, the invention can fully exert the purification function of the wetland and enhance the denitrification effect by changing the water flow path of the wetland, thereby reducing the concentration of pollutants in effluent of the wetland and lightening the pollution load of the effluent of the wetland entering the lake: in dry seasons, the reflux nitrifying liquid is subjected to nitrification and denitrification reactions in the subsurface flow wetland by a reflux method, TN is further removed, 90% of TN can be removed by the whole wetland system, and the removal capacity of TN is improved by 10%; in rainy season, by using a backflow method and using the filler of the subsurface wetland to perform ion exchange and physical adsorption on granular nitrogen and nitrate nitrogen in the inlet water, TN in the water can be greatly reduced, and 89% of TN can be removed by the whole wetland system by combining the plant absorption and microbial purification effects of the natural wetland and the surface flow wetland, and the TN removal capacity is improved by 9%;

2. under the condition of not changing original construction layout, through the change of rivers route, easy operation, reducible work load reduces the cost, is fit for promoting.

Drawings

FIG. 1 is a schematic view of a water flow path structure of the dry season backflow method;

FIG. 2 is a schematic view of a water flow path structure of the method for backflow in rainy season;

in the figure: 1. surface flow wetland, 2 natural wetland and 3 underflow wetland.

Detailed Description

The invention is further illustrated by the following figures and examples, without however restricting the scope of the invention to these examples.

Example 1

A wetland system for enhancing denitrification comprises a surface flow wetland, a natural wetland and an undercurrent wetland which are sequentially arranged along the water flow direction; a reflux device is also arranged between the subsurface flow wetland and the natural wetland, the reflux device comprises a reflux pipe and a reflux pump, and the effluent of the dry season subsurface flow wetland can be refluxed to the natural wetland through the reflux device; and a backflow device is also arranged among the subsurface flow wetland, the natural wetland and the surface flow wetland, the backflow device comprises a flow guide pipe and a flow guide pump, and the inflow water in rainy seasons can sequentially pass through the subsurface flow wetland, the natural wetland and the surface flow wetland through the backflow device.

The bottoms of the surface flow wetland and the subsurface flow wetland are tamped by plain soil, and an impermeable layer is artificially laid above the plain soil; a packing layer is also arranged above the anti-seepage layer of the subsurface wetland, the packing layer sequentially consists of a drainage layer, a filter material layer and a planting soil layer from bottom to top, the drainage layer is paved by pebbles with the particle size of 30-80 mm, and the thickness of the drainage layer is 200 mm; the filter material layer is paved by zeolite with the particle size of 15-30 mm, and the thickness of the filter material layer is 700 mm; the planting soil layer is covered by planting soil, and the thickness of the planting soil layer is 200 mm.

Tamped density of plain soil>95 percent, and the permeability coefficient of the impermeable layer is less than or equal to 10^-8cm/s。

The surface flow wetland ground is taken as a relative elevation zero point, and the water depth of the surface flow wetland, the natural wetland and the subsurface flow wetland is 0.3-0.5 m.

Aquatic plants are planted in the surface flow wetland, the natural wetland and the subsurface flow wetland. The aquatic plant is herba Alii Fistulosi and rhizoma Typhae, and has planting density of 6 clusters/m²。

A method for treating sewage by a wetland system for enhancing denitrification comprises the following steps:

(1) refluxing in dry seasons: in dry seasons, the inlet water flows through the surface flow wetland, the natural wetland and the subsurface flow wetland in sequence, and then the outlet water flows back to the natural wetland through the backflow device; secondly, carrying out secondary nitrification and denitrification reactions on nitrate nitrogen and nitrite nitrogen in the effluent in the subsurface flow wetland by using raw water as a carbon source through the subsurface flow wetland so as to enhance the denitrification capability of the wetland, and finally discharging the denitrified water into a receiving water body;

(2) backflow in rainy season: in rainy season, the inlet water is led to the subsurface flow wetland through the backflow device, and the filler of the subsurface flow wetland is utilized to carry out ion exchange and physical adsorption on granular nitrogen and nitrate nitrogen in the inlet water so as to reduce the total nitrogen concentration; then sequentially passing through the natural wetland and the surface flow wetland, further reducing the total nitrogen concentration through plant absorption and microbial degradation in the natural wetland and the surface flow wetland, and finally discharging into a receiving water body.

The reflux ratio in the dry season reflux method is 1: 3.

The dry season hydraulic load of the surface flow wetland, the natural wetland and the subsurface flow wetland is respectively 0.153, 0.017 and 0.278m³/(m²D), the pollution load of the surface flow wetland is 12.21 kgTN/(hm)²D), the pollution loads of the natural wetland and the subsurface wetland are respectively 10 percent and 60 percent of that of the surface flow wetland, and the hydraulic retention time of the three is respectively 47.18, 953.70 and 25.94 h.

The hydraulic loads of the surface flow wetland, the natural wetland and the subsurface flow wetland in rainy season are respectively 0.763, 0.083 and 1.388m³/(m²D) pollution load of surface flow wetland is 61.05 kgTN/(hm)²D) natural wetlandThe pollution load of the subsurface flow wetland and the pollution load of the subsurface flow wetland are respectively 9 percent and 60 percent of that of the surface flow wetland, and the hydraulic retention time of the three is respectively 15.73, 248.62 and 8.65 hours.

The method is applied to a certain wetland of the lakeside of the Yunnan plateau lake, the TN of the inlet water and the outlet water of the original process is monitored in rainy season and dry season, the TN of the water body after the waterway optimization is predicted, and the analysis is shown in the following table 1.

TABLE 1 TN monitoring and comparison of certain wetlands on lakeside of Yunnan plateau lake

As can be seen from Table 1, after the reflux operation, the removal of total nitrogen by the wetland can be improved by 10% in a prediction mode, and the effluent can reach the IV-class water standard of surface water; after the backflow operation, the removal of TN by the wetland is predicted to be improved by 9 percent, and the effluent can reach the III-class water standard of surface water; the denitrification function of the wetland is enhanced.

Example 2

The reflux ratio in the dry season reflux method is 1: 1.

The aquatic plants are herba Alii Fistulosi and rhizoma Phragmitis, and the planting density is 2 clusters/m²。

The rest is the same as example 1.

Example 3

The reflux ratio in the dry season reflux method is 1: 2.

The aquatic plant is Typha angustifolia and Phragmites communis, and the planting density is 10 clusters/m²。

The rest is the same as example 1.