A stepped bioretention facility

Abstract

The application provides a stepped biological retention facility, comprising: a plurality of retention units arranged in a stepped manner, adjacent retention units being separated by water-permeable partitions, a first-level retention unit from low to high has, from top to bottom, a planting soil layer and a first filter material layer, a second-level retention unit from low to high has, from top to bottom, a planting soil layer, a first filter material layer and a second filter material layer, a third-level retention unit from low to high has, from top to bottom, a planting soil layer, a first filter material layer, a second filter material layer and a third filter material layer, and the rest of the retention units have, from top to bottom, a planting soil layer, a first filter material layer, a second filter material layer and a plurality of third filter material layers; the first filter material layer, the second filter material layer and the third filter material layer are respectively inoculated with complete nitrification bacteria, denitrifying bacteria and phosphorus accumulating bacteria. The retention facility can be arranged in an area with a large slope, and can efficiently reduce the input of agricultural non-point source nitrogen and phosphorus pollution through the cooperation of fillers and microorganisms.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of water treatment, and particularly relates to a ladder-shaped biological retention facility. BACKGROUND

[0002] The biological retention facility refers to a facility for storing and purifying runoff rainwater through a plant, soil and microbial system in a low-lying area, and is mainly applicable to the surrounding green land of buildings, roads and parking lots, and urban green land such as parks. In some cities mainly composed of hills and mountains, the road undulates greatly, and the ordinary biological retention facility is only applicable to the flat area of squares or roads due to the structural characteristics, and cannot meet the drainage, purification and aesthetic requirements in the case of a large road slope. Moreover, the existing biological retention facility has defects such as short service life, high maintenance cost, poor nitrogen and phosphorus removal efficiency, etc. Since 2000, agriculture has become the largest source of water pollution in China, which seriously affects the water quality of lakes and rivers. The agricultural non-point source nitrogen and phosphorus pollution has gradually become the focus of water purification treatment in China. In some areas with large slopes, it is a technical challenge for the current agricultural non-point source pollution treatment to efficiently reduce the input of agricultural non-point source nitrogen and phosphorus pollution and reduce its contribution to the nutrient salt of surface water through the biological retention facility. SUMMARY

[0003] In order to solve the defects of the prior art, the present application provides a ladder-shaped biological retention facility which can be arranged in an area with a large slope and can efficiently reduce the input of agricultural non-point source nitrogen and phosphorus pollution through the cooperation of fillers and microorganisms.

[0004] In order to achieve the above-mentioned purpose, the present application adopts the following technology:

[0005] A ladder-shaped biological retention facility comprises:

[0006] The retention units are arranged in multiple levels of ladders, adjacent retention units are separated by a water-permeable partition plate, the bottom heights of the retention units are the same, the first level of retention units from low to high are sequentially arranged from top to bottom as a plant soil layer, a first filter layer, the second level of retention units from low to high are sequentially arranged from top to bottom as the plant soil layer, the first filter layer, a second filter layer, the third level of retention units from low to high are sequentially arranged from top to bottom as the plant soil layer, the first filter layer, the second filter layer, a third filter layer, the remaining retention units are sequentially arranged from top to bottom as the plant soil layer, the first filter layer, the second filter layer, and multiple layers of the third filter layer, the number of layers of the third filter layer is the number of levels from low to high minus 2, a water-permeable cloth is arranged below the plant soil layer and between different filter layers, full nitrification bacteria are inoculated in the first filter layer, denitrifying bacteria are inoculated in the second filter layer, and phosphorus accumulating bacteria are inoculated in the third filter layer.

[0007] Further, the top of each level of the retention unit is provided with a water storage baffle for retaining the water to be treated above the soil layer, and the top of the first level of the retention unit to the top of the n-1 level of the retention unit is provided with a water guide pipe along the length direction, wherein n is an integer greater than or equal to 3, representing the number of the retention units, the top of the water guide pipe is connected with a vertical overflow pipe, the top of the overflow pipe is lower than the top of the water storage baffle, and one end of the water guide pipe penetrates through the water storage baffle and is connected with the second filter layer and the third filter layer in the same row through a connecting pipe.

[0008] Further, the second filter layer and the third filter layer are provided with a water inlet pipe along the length direction, and the bottom of the water inlet pipe is provided with a plurality of drainage holes along the length direction, and the water inlet pipe in the second filter layer and the third filter layer in the same row is connected with one end of the water guide pipe in the same row through a connecting pipe.

[0009] Further, the bottom of the highest retention unit is connected with a drainage pipe.

[0010] Further, the particle size of the fillers in the first filter layer, the second filter layer and the third filter layer increases in turn.

[0011] Further, modified limestone and zeolite fillers are selected as the first filter layer, pyrite fillers are selected as the second filter layer, and volcanic rock fillers are selected as the third filter layer.

[0012] Further, the modified limestone is obtained through the processes of heating, alkali washing, cleaning, drying and grinding.

[0013] Further, when the full-nitrification bacteria, denitrifying bacteria and phosphorus accumulating bacteria are inoculated, the full-nitrification bacteria, denitrifying bacteria and phosphorus accumulating bacteria are respectively enriched in sludge, and then diluted with clean water to 30000mg / L-4000mg / L, and then leached into the corresponding filter layer in multiple times.

[0014] The present application has the following advantages:

[0015] 1. The biological retention facility can be arranged in an area with a large slope, and can efficiently reduce the input of agricultural non-point source nitrogen and phosphorus pollution through the cooperation of fillers and microorganisms.

[0016] 2. When the height of the water in the water storage baffle is higher than that of the overflow pipe, the water will flow into the water guide pipe through the overflow pipe, and then flow into the second filter layer and the third filter layer in the same row through the connecting pipe, so that part of the water directly enters the second filter layer and the third filter layer without passing through the soil layer and the first filter layer, and the denitrifying bacteria and phosphorus accumulating bacteria directly obtain part of the carbon source in the water to be treated, thereby avoiding the decrease of the number of nitrifying bacteria and phosphorus accumulating bacteria due to the long-term acquisition of less carbon source or the inability to acquire carbon source, and affecting the purification effect. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 A perspective view of a structure of a detention facility according to an embodiment of the present application.

[0018] Figure 2 A side view of a partial structure of a detention facility according to an embodiment of the present application.

[0019] Figure 3 A perspective view of a partial structure of a detention facility according to an embodiment of the present application. Figure 2 A magnified view of a middle A part.

[0020] Figure 4 A perspective view of a partial structure of a detention facility according to an embodiment of the present application.

[0021] Figure 5 A perspective view of another partial structure of a detention facility according to an embodiment of the present application.

[0022] Figure 6 A perspective view of a partial structure of a detention facility according to an embodiment of the present application. Figure 5 A magnified view of a middle B part.

[0023] Reference numerals: soil layer 1, first filter layer 2, second filter layer 3, third filter layer 4, water-permeable partition 5, water-permeable cloth 6, water storage baffle 7, water guide pipe 8, overflow pipe 9, connection pipe 10, water inlet pipe 11, drainage hole 1101, drainage pipe 12, fixing plate 13. DETAILED DESCRIPTION

[0024] In order to make the objects, technical solutions, and advantages of embodiments of the present application clearer, the embodiments of the present application will be described in detail below with reference to the drawings, but the embodiments described in the present application are only part of the embodiments of the present application, rather than all the embodiments of the present application.

[0025] An embodiment of the present application provides a stepped biological detention facility, as shown in FIG. 1, which includes a detention unit, a water-permeable cloth 6, a water-permeable partition 5, and the like. Figures 1-6

[0026] ​Specifically, the retention units are arranged in multiple levels, adjacent retention units are separated by water-permeable partitions 5, the bottom heights of the retention units are the same, the first level of retention units from low to high has, from top to bottom, the soil layer 1, the first filter material layer 2, the second level of retention units from low to high has, from top to bottom, the soil layer 1, the first filter material layer 2, the second filter material layer 3, the third level of retention units from low to high has, from top to bottom, the soil layer 1, the first filter material layer 2, the second filter material layer 3, the third filter material layer 4, and the remaining retention units have, from top to bottom, the soil layer 1, the first filter material layer 2, the second filter material layer 3, and multiple third filter material layers 4, the number of the third filter material layers 4 is the level number of the retention unit minus 2, the water-permeable cloth 6 is arranged below the soil layer 1 and between adjacent filter material layers in the vertical direction, the first filter material layer 2 is inoculated with full-nitrification bacteria, the second filter material layer 3 is inoculated with denitrifying bacteria, and the third filter material layer 4 is inoculated with phosphorus accumulating bacteria.

[0027] In one embodiment, referring to Figure 2 , a ladder-shaped bioretention facility with a total of five levels of retention units is shown, wherein the fourth level of retention units from low to high has, from top to bottom, the first filter material layer 2, the second filter material layer 3, and two third filter material layers 4, and the fifth level of retention units from low to high has, from top to bottom, the first filter material layer 2, the second filter material layer 3, and three third filter material layers 4. In actual use, the water inlet mode can be horizontal overflow, vertical underflow, and horizontal overflow through the holes between the water-permeable partitions 5, the biofilm bacteria species are different between each layer of filler, and layered biofilm can reduce the influence of miscellaneous bacteria on the treatment effect. The water to be treated passes through the multiple filter material layers from the soil layer 1 at the top of each retention unit, the water infiltrated in the third level to the fifth level of retention units from low to high passes through the first filter material layer 2, the second filter material layer 3, and the third filter material layer 4, and is absorbed by the full-nitrification bacteria, the denitrifying bacteria, and the phosphorus accumulating bacteria inoculated in turn, the water infiltrated in the first level to the second level of retention units from low to high can penetrate horizontally through the water-permeable partitions 5, and can also pass through the first filter material layer 2, the second filter material layer 3, and the third filter material layer 4, and be absorbed by the full-nitrification bacteria, the denitrifying bacteria, and the phosphorus accumulating bacteria inoculated in turn, so that the bioretention facility can still have a good removal rate of ammonia nitrogen and phosphorus under the dual purification of multiple fillers and biological treatment under high ammonia nitrogen and high phosphorus load. Specifically, referring to Figure 2 , Figure 4 , the third filter material layer 4 at the bottom of the highest retention unit is connected with the drainage pipeline 12, and excess water accumulated at the bottom of the retention unit can be discharged through the drainage pipeline 12.

[0028] Specifically, referring to Figure 4The top of each retention unit is provided with a water storage baffle 7 for retaining the water to be treated above the soil layer 1. The top of the first to the n-1 retention units from low to high is provided with a water guide pipe 8 along the length direction. n is an integer greater than or equal to 3, representing the number of retention units. The top of the water guide pipe 8 is connected with a vertical overflow pipe 9. The top of the overflow pipe 9 is lower than the top of the water storage baffle 7. One end of the water guide pipe 8 penetrates through the water storage baffle 7 and is connected with the second filter material layer 3 and the third filter material layer 4 in the same row through a connecting pipe 10. Figure 2 、 Figure 3 When n is 5, as shown in the drawings, the top of the first to the fourth retention units from low to high is provided with a water guide pipe 8 along the length direction. When the water level in the water storage baffle 7 is higher than the overflow pipe 9, the water flows into the water guide pipe 8 from the overflow pipe 9 and then flows into the second filter material layer 3 and the third filter material layer 4 in the same row through the connecting pipe 10, so that part of the water does not pass through the soil layer 1 and the first filter material layer 2 and directly enters the second filter material layer 3 and the third filter material layer 4, so that the denitrifying bacteria and the phosphorus accumulating bacteria directly obtain part of the carbon source in the water to be treated. Avoiding that the carbon source in the water is first absorbed and utilized by the full nitrification bacteria in the soil layer 1 and the first filter material layer 2 and then flows into the subsequent filter material layer, so that the denitrifying bacteria and the phosphorus accumulating bacteria in the second filter material layer 3 and the third filter material layer 4 obtain too little carbon source, which affects the removal effect of ammonia nitrogen and phosphorus and the growth and reproduction of the bacteria.

[0029] More specifically, referring to Figure 1 The second filter material layer 3 and the third filter material layer 4 are provided with a water inlet pipe 11 along the length direction. The bottom of the water inlet pipe 11 is provided with a plurality of drainage holes 1101 along the length direction. The water inlet pipe 11 in the second filter material layer 3 and the third filter material layer 4 in the same row is connected with one end of the water guide pipe 8 in the same row through the connecting pipe 10. The water to be treated enters the water inlet pipe 11 through the connecting pipe 10 and then flows downward into the second filter material layer 3 and the third filter material layer 4 through the plurality of drainage holes 1101 at the bottom of the water inlet pipe, so that the water distribution is more uniform. More specifically, referring to Figure 5 The fixed plate 13 can be arranged on both sides of the retention unit for fixing the connecting pipe 10 and the water inlet pipe 11.

[0030] Specifically, the particle size of the fillers in the first filter material layer 2, the second filter material layer 3 and the third filter material layer 4 increases in turn, so as to improve the water permeation speed. In an embodiment, the modified limestone filler and the zeolite filler are selected as the first filter material layer 2, the pyrite filler is selected as the second filter material layer 3, and the volcanic rock filler is selected as the third filter material layer 4. Because the modified limestone and the zeolite have good adhesion to the full nitrification bacteria, the pyrite can appropriately promote the denitrification process of the denitrifying bacteria, and the volcanic rock has good adhesion effect on the phosphorus accumulating bacteria, so that the removal effect of the retention facility on the ammonia nitrogen and the phosphorus in the water can be improved.

[0031] Specifically, the modified limestone is obtained through the processes of heating, alkali washing, cleaning, drying and grinding, and the surface voids of the modified limestone are increased, so that the inoculation effect of the whole nitrifying bacteria and the adsorption effect on ammonia nitrogen are further improved.

[0032] Specifically, when inoculating the whole nitrifying bacteria, denitrifying bacteria and phosphorus accumulating bacteria, the whole nitrifying bacteria, denitrifying bacteria and phosphorus accumulating bacteria are respectively enriched in sludge, and then diluted with clean water to 30000 mg / L-4000 mg / L, and then added into the corresponding filter material layer in multiple times, so that the surface of the filler in each filter material layer is infiltrated with sludge water containing corresponding bacteria, and the uniformity of inoculation is improved.

[0033] Under the standard working condition (rainfall depth 25 mm, rainfall duration 2 hours), the simulated rainfall TN (total nitrogen) is 8 mg / L, TP (total phosphorus) is 0.5 mg / L, and COD (chemical oxygen demand) is 18.2 mg / L. After 20 times of water inflow of the ladder-shaped biological retention facility, the pollutant removal effect is shown in Table 1. The removal rate of TN is 80%, the removal rate of TP is 78%, and the removal rate of COD is 83.5%, all reaching a high removal effect.

[0034] Table 1. Operation condition table

[0035] Contaminants Dosing substance (concentration) Influent concentration (mg / L) Effluent concentration (mg / L) <![CDATA[NO3 - -N]]> Potassium nitrate (21.7 mg / L) 3 0.3 <![CDATA[NH4 - -N]]> Ammonium chloride (7.6 mg / L) 2 0.7 TN / 5 1.0 TP Potassium dihydrogen phosphate (2.2 mg / L) 0.5 0.11 COD Sodium acetate (17 mg / L) 18.2 3

[0036] Specifically, the test method is as follows: first, configure simulated rainwater: add 180 L tap water in a 200 L PE dosing barrel, and stand for at least 24 hours to reduce the influence of residual chlorine. Stir and aerate before each test, to simulate the high dissolved oxygen characteristics of actual rainwater. Then add the prepared pollutant stock solution, make up to 200 L, and stir clockwise for 15 min. The water preparation substances and concentrations are shown in Table 1. The uniform rainfall method is used to simulate the standard working condition rainfall. Collect all the effluent, and test the pollutant concentration.

[0037] The above description is only preferred embodiments of the present application, and does not mean that it is the only or limited one. Those skilled in the art should understand that various changes or equivalent replacements made to the present application without departing from the scope of the present application, all belong to the scope of protection of the present application.

Claims

1. A stepped bioretention facility, characterized in that: The invention comprises a multi-stage stepped retention unit, wherein adjacent retention units are separated by a permeable partition (5), and the bottom heights of the retention units are the same. From low to high, the first-stage retention unit is sequentially composed of a planted soil layer (1) and a first filter material layer (2) from top to bottom, the second-stage retention unit is sequentially composed of a planted soil layer (1), a first filter material layer (2), and a second filter material layer (3) from top to bottom, and the third-stage retention unit is sequentially composed of a planted soil layer (1), a first filter material layer (2), a second filter material layer (3), and a third filter material layer (4) from top to bottom. ), the remaining retention units are, from top to bottom, a planted soil layer (1), a first filter material layer (2), a second filter material layer (3), and a multi-layer third filter material layer (4). The number of layers of the third filter material layer (4) is the number of levels from low to high of the retention unit minus 2. Permeable cloth (6) is provided below the planted soil layer (1) and between the filter material layers adjacent in the vertical direction. The first filter material layer (2) is inoculated with full-process nitrifying bacteria, the second filter material layer (3) is inoculated with denitrifying bacteria, and the third filter material layer (4) is inoculated with polyphosphate bacteria. A water storage baffle (7) is provided on the top of each level of retention unit for storing the water to be treated above the plant soil layer (1). A water diversion pipe (8) is provided on the top of each level of retention unit from the first level to the n-1 level along the length direction, where n is an integer greater than or equal to 3, representing the number of retention units. The top of each level of retention unit (8) is connected to an overflow pipe (9) arranged vertically. The top height of the overflow pipe (9) is lower than the top height of the water storage baffle (7). One end of the water diversion pipe (8) passes through the water storage baffle (7) and is connected to the second filter material layer (3) and the third filter material layer (4) in the same row through a connecting pipe (10); A water inlet pipe (11) is provided in the second filter material layer (3) and the third filter material layer (4) along the length direction, and a plurality of drainage holes (1101) are provided in an array at the bottom of the water inlet pipe (11) along the length direction. The water inlet pipes (11) in the second filter material layer (3) and the third filter material layer (4) in the same row are connected to one end of the water diversion pipe (8) in the same row through a connecting pipe (10).

2. The stepped bioretention facility according to claim 1, characterized in that: The bottom of the highest retention unit is connected to the drainage pipe (12).

3. The stepped bioretention facility according to claim 1, characterized in that: The particle sizes of the fillers in the first filter material layer (2), the second filter material layer (3), and the third filter material layer (4) increase in sequence.

4. The stepped bioretention facility according to claim 1, characterized in that: The first filter material layer (2) uses modified limestone and zeolite as fillers, the second filter material layer (3) uses pyrite as filler, and the third filter material layer (4) uses volcanic rock as filler.

5. The stepped bioretention facility according to claim 4, characterized in that: The modified limestone is obtained through the processes of heating, alkali washing, cleaning, drying, grinding and crushing.

6. The stepped bioretention facility according to claim 1, characterized in that: When inoculating full-process nitrifying bacteria, denitrifying bacteria, and polyphosphate bacteria, first enrich the full-process nitrifying bacteria, denitrifying bacteria, and polyphosphate bacteria in the sludge respectively, and dilute them with clean water to 30,000 mg / L-4,000 mg / L, and then sprinkle them into the corresponding filter material layer several times.

Images