CN1994940A - Circulated backfilling and artificial wetland combined leachate processing method and its facility - Google Patents

Abstract

A leachate treatment method combined with recirculation and artificial wetlands, comprising the following steps: making the landfill leachate pass through a grid well to remove some suspended solids and impurities with larger particle sizes; Remove a part of sand and suspended matter; let part of the landfill leachate in the first grid of the above-mentioned regulating tank be recharged to the landfill through the leachate recharge system, and the other part pass through the pre-treatment of the second grid of the regulating tank and the third grid of the regulating tank. After treatment, it is poured into the artificial wetland system for treatment, and the effluent is discharged after reaching the standard. The total residence time of the sewage in the regulating tank is 15 to 30 days. A leachate treatment facility for realizing the above method, including a grid well, a regulating tank, a circulation recharge system and a constructed wetland system, the regulating tank is optimized into three grids, a rotary grid is arranged in the grid well, and the grid The grid well outlet is directly connected with the first grid of the regulating tank. The invention has low cost input, is suitable for leachate of various landfill ages, and has the function of landscape restoration.

Description

A leachate treatment method and its facilities for combined use of circulating irrigation and constructed wetlands

technical field

The invention belongs to the technical fields of environmental protection and sewage treatment, and in particular relates to a leachate treatment method and facilities of domestic waste landfill.

Background technique

Landfill leachate is the secondary pollution produced in the landfill process. It is a kind of high-concentration organic wastewater with complex components. It mainly comes from precipitation and the embedded water of the landfill waste itself. one of the environmental problems. It can pollute water bodies, soil, atmosphere, etc., make surface water bodies hypoxic, deteriorate water quality, and become eutrophic, threaten drinking water and industrial and agricultural water sources, and make groundwater lose its use value. Organic pollutants entering the food chain will directly threaten human health.

As people pay more and more attention to the problem of landfill leachate, various leachate treatment methods have been widely developed. Commonly used leachate treatment methods generally include physical and chemical methods, biochemical methods and land methods.

Physical and chemical methods are generally used as pretreatment or advanced treatment to create good conditions for the discharge of leachate up to the standard and the effective operation of the biological treatment system. Physicochemical treatment is generally not affected by the water quality and quantity of leachate, and the effluent water quality is relatively stable, especially for leachate with a low BOD/COD ratio (0.07-0.20), which is difficult to biochemically treat, and has a good treatment effect. When the COD concentration is 2000 ~ 4000mgL ^-1 , the COD removal rate of physicochemical method can generally reach 50% ~ 80%. However, the physical and chemical treatment technology is too targeted, the treatment effect is single, and the cost is high, so it is not suitable for the treatment of large amounts of leachate.

The biochemical method includes aerobic treatment, anaerobic treatment and a combination of the two. It has the advantages of good treatment effect, simple operation, low investment and operation costs, and is suitable for treating leachate with good biochemical properties. However, it is difficult to remove the degraded organic components with relatively small molecular weight by biochemical method, and it is difficult to reduce the COD of the effluent to below the national standard. The most serious defect of the biochemical method in the process of treating leachate is that it has almost no treatment effect on the "old" leachate with a small BOD/COD ratio.

The land method mainly removes the suspended solids in the filtrate through the filtration of soil particles, ion exchange, adsorption and precipitation, and fixes the soluble components on the particles. At the same time, the organic matter and nitrogen in the leachate are transformed and stabilized by microorganisms in the soil, and the amount of leachate is reduced through transpiration. At present, the land methods used for landfill leachate treatment mainly include recharge method and constructed wetland method. However, land law generally covers a larger area.

Large changes in water quality and quantity of landfill leachate, imbalanced proportion of nutrient elements, ammonia nitrogen content and other characteristics make its treatment difficult. Realizing its economical and effective treatment is still a research hotspot and difficulty in landfill treatment technology.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art, and provide a kind of garbage with low cost input, good treatment effect, simple operation, low operation and maintenance cost, suitable for leachate of various landfill ages, and with landscape restoration function Leachate treatment method and its facilities.

In order to solve the above problems, the present invention adopts the following technical solutions:

A leachate treatment method combined with recirculation and artificial wetland, comprising the following steps:

a. Let the landfill leachate pass through the grid well to remove some suspended solids and sundries with larger particle sizes;

b. Concentrate the above-mentioned treated landfill leachate in the first compartment of the adjustment tank to remove part of the sand and suspended matter;

c. Recharge part of the landfill leachate in the first compartment of the above-mentioned regulating pool to the landfill through the leachate recharge system, and pour the other part into the constructed wetland after pretreatment in the second compartment of the regulating pool and the third compartment of the regulating pool The system conducts treatment, and the effluent is discharged after reaching the standard. The total residence time of sewage in the regulating tank is 15 to 30 days.

The specific steps for recharging the landfill leachate to the landfill through the leachate recharge system are: 1) using the leachate recharge lift pump to lift the landfill leachate in the first grid of the regulating tank to the water distribution pump room; 2) ) input the landfill leachate in the above-mentioned water distribution pump room into the reinjection well through high-density polyethylene (HDPE) pipes, and reinfuse it into the landfill through the reinjection ditch on both sides of the reinjection well; 3) through the filling The leachate collection pipeline at the bottom of the landfill collects the leachate from the above-mentioned landfill to the adjustment tank, the refilling frequency is 1-2 times/d, and the refilling hydraulic load is 0.01-0.1m ³ /m ² .d.

The submersible aerator at the bottom of the second grid of the adjustment tank performs uninterrupted aeration, and the range of action of a single unit is 4-8m; the sludge pump installed at the bottom of the third grid regularly discharges sludge, and the lifting pump at the bottom of the third grid will The landfill leachate is transported to the distribution well of the constructed wetland system. The hydraulic retention time of the constructed wetland system unit is 6-12 hours; when the average temperature is higher than 15°C, the hydraulic load is 10-15L/m ² .d; when the average temperature is 4-15°C, the hydraulic load is 5-10L/m ² . d; When the average temperature is lower than 4°C or when the daily rainfall is 4-15mm, the hydraulic load is 3-5L/m ² .d; when the daily rainfall is greater than 15mm, stop water intake.

A leachate treatment facility that implements the above leachate treatment method, including a grid well, a regulating tank placed behind the grid well, a circulation recharge system and a constructed wetland system. The regulating tank is optimized into three grids to form anoxic - Aerobic-hypoxic functional model. A rotary grille is installed in the grill well, and the water outlet of the grill well is directly connected with the first grid of the regulating tank.

The effective volume of the first compartment of the regulating tank is 60% to 80% of the total effective volume of the regulating tank, the effective volume of the second compartment and the third compartment are the same, and a leachate recharge lift pump is installed in the first compartment, and a leachate recharge pump is installed in the second compartment Set 1 to 4 submersible aerators at the bottom of the grid, and set a sludge pump and a lift pump at the bottom of the third grid. The circulation and recharge system sequentially includes a water distribution pump house, a recharge well connected to the water distribution pump house through HDPE pipes, and recharge ditches on both sides of the recharge well. Recharge wells are set every 40-50m, and a recharge ditch is designed on the left and right sides of the recharge well. The structure of the recharge ditch is: a perforated water distribution pipe in the middle, filled with graded gravel around, and covered with a layer of compacted clay.

The constructed wetland system is divided into constructed wetland units of different shapes and areas according to the terrain, and the units are connected in series and parallel according to actual needs. The length of the constructed wetland unit is 20-50m, and the length:width=1-3: 1. The water outlet of the water distribution well is connected to the water distribution pipe of the constructed wetland unit. In winter, when the wetland plants wither, the surface of the constructed wetland unit is covered with a 0.1-0.5mm thick polyethylene film. The wetland plants are emergent plants. When the constructed wetland unit is located in the final cover layer of the landfill, the site of the final cover layer of the landfill site is directly used to construct the constructed wetland unit, and the constructed wetland unit is arranged above the garbage layer from bottom to top: clay layer, HDPE anti-seepage membrane sealing layer, synthetic Material diversion layer, filling layer, and vegetation layer, and perforated water distribution pipes are set at the front end of the constructed wetland unit; The perforated diversion pipe is laid, and the sand and gravel diversion layer is covered with a clay layer. After leveling, it is covered with an HDPE anti-seepage membrane sealing layer. Water pipes, water pipes are higher than the vegetation layer.

When the constructed wetland unit is located in the final cover layer of the landfill, the thickness of the clay layer is 0.2-0.3m, the thickness of the HDPE anti-seepage membrane sealing layer is ≥1mm, the thickness of the synthetic material diversion layer is 0.2-0.3m, and the thickness of the filling layer is ≥ 0.3m, vegetation layer thickness ≥ 0.3m, perforated water distribution pipe 3-5m long, water distribution pipe 0.3-0.6m higher than the vegetation layer; when the constructed wetland unit is located outside the landfill area, the ground slope is 1%-2% , the thickness of the sand and gravel diversion layer is 0.2m, the diameter of the sand and gravel is ≤1cm, and a perforated water pipe is laid at an interval of 10m in the sand and gravel diversion layer. The thickness of the sandstone layer on the anti-seepage membrane is 0.2m, the thickness of the filling layer and the vegetation layer are not less than 0.3m, the perforated water distribution pipe is about 3-5m long, and the water distribution pipe is 0.3-0.6m higher than the vegetation layer.

The plants planted in the unit vegetation layer of the constructed wetland are mainly emergent plants such as reed, water sedge, bamboo, cattail, canna, yellow bamboo grass, water onion, water sedge and rush grass. The same plant is planted in the same unit, but different plants need to be planted in different units according to the landscape needs and sewage characteristics, and the plants are harvested regularly.

The advantages of the present invention are:

1. The present invention organically combines the sewage treatment technology with the landscape restoration technology, and while the leachate treatment reaches the national first-class discharge standard (GB16889-1997), the landfill has been landscape restored.

2. The present invention has the effect of reducing the amount of leachate discharge, and both the leachate recharge system and the constructed wetland system can greatly reduce the total amount of leachate by means of interception and evaporation.

3. The regulating pool of the present invention has been optimized in function, and can initially treat the leachate while accumulating the leachate, reducing the load pressure of the constructed wetland system.

4. The present invention is suitable for leachate treatment of any landfill age, and with the increase of the service life of the landfill, the construction area of the obtained constructed wetland will be larger, and the leachate treatment capacity will gradually increase accordingly.

5. The implementation cost of the present invention is low, especially when the landfill is subdivided and finally covered, the construction of the constructed wetland directly uses the structure of the final covering layer, and only needs to separate the wetland units and increase the corresponding water delivery and distribution. water facilities.

6. The present invention can accelerate the decomposition of garbage, accelerate the stabilization process of garbage, and increase the rate and amount of methane production of garbage.

7. The present invention not only does not require external substances and energy sources to regulate water quality, but also enables plants to utilize water, nitrogen and organic substances in the leachate and convert them into recyclable biological materials.

Description of drawings

Fig. 1 is a process flow diagram of the present invention;

Fig. 2 is the schematic diagram of the regulating pool of the present invention;

Fig. 3 is the schematic diagram of the circulating refilling system of the present invention;

Fig. 4 is a schematic cross-sectional view of a refill ditch of the present invention;

Fig. 5 is the schematic cross-sectional view of the constructed wetland unit located in the final cover layer of the landfill according to the present invention;

Fig. 6 is a schematic cross-sectional view of a constructed wetland unit located outside the landfill area of the present invention.

The labels in the accompanying drawings are explained as follows:

1. The first grid of the adjustment pool 2. The second grid of the adjustment pool 3. The third grid of the adjustment pool

4. Leachate recharge lift pump 5. Submersible aerator 6. Sludge pump

7. Lift pump 8. Grid well 9. Leachate collection pipe

10. Reinjection well 11. Solid waste 12. Water distribution pump room

13. Compacted clay 14. Graded crushed stone 15. Perforated water distribution pipe

16. Perforated water pipes 17. Vegetation layer 18. Filling soil layer

19. Synthetic material diversion layer 20. HDPE anti-seepage membrane sealing layer 21. Clay layer

22. Garbage layer 23. Outlet pipe 24. Sand and gravel layer

25. Clay layer on sand and gravel diversion layer 26. Sand and gravel diversion layer 27. Perforated diversion pipe

Detailed ways

The process flow of the embodiment of the present invention is shown in Fig. 1 .

Example 1

In a newly built landfill site, the grid well 8 (as shown in Figure 3) is set in the northwest corner of the north side of the adjustment pool, the size is length × width = 2000mm × 700mm, and the effective water depth is 1.95m. There is one rotary mechanical grille with an effective grille width of 0.7m and a power distribution motor of 1.2kW. The south end of the grille well has a hole of 300mm×300mm connected to the regulating pool.

As shown in Figure 2, the effective volume of the regulating pool is 3600m ³ and the effective water depth is 3m. The size of the first grid 1 of the regulating tank is length×width=36m×25m, the dimensions of the second grid 2 and the third grid 3 of the regulating tank are both length×width=12m×25m, and the total hydraulic retention time of the regulating tank is 20 days. Two submersible aerators are installed in the second cell for uninterrupted aeration, with a range of 5m and a motor power of 3.7kW. Set up 6 sets of sludge pumps (flow rate 12.5m ³ /h, head 9m, distribution motor power 0.75kW) at the bottom of the third tank to discharge sludge regularly, and install 7 sets of lift pumps (flow rate 12.5m ³ /h , head 20m, distribution motor power 2kW), the leachate is transported to the water distribution well of the constructed wetland system, and the outlet of the water distribution well is connected to the perforated water distribution pipe 16 of the constructed wetland unit (as shown in Figure 5).

The leachate in the first cell of the regulating tank is recharged to the landfill through the circulating recharge system, as shown in Figure 3, the specific way to realize the recirculating recharge system is: firstly, the leachate is recharged by the lift pump 4 to the second cell of the regulating tank. The leachate in one grid is lifted to the water distribution pump room 12, and then the HDPE pipe transfers the landfill leachate in the water distribution pump room into the reinjection well 10, and it is recharged to the landfill by the recharge ditch on both sides of the reinjection well. In the landfill, the leachate from the above-mentioned landfill is collected into the adjustment pool through the leachate collection pipeline 9 at the bottom of the landfill. Reinjection wells are set every 50m, and a 50m×2m×0.5m recharge ditch is designed on the left and right sides of the reinjection well. Cover with a layer of compacted clay 13 . The recharge frequency is 2 times/d, and the recharge hydraulic load is 0.5m ³ /m ² .d.

After multiple cycles of recharge, the adsorption of soil in the landfill and the decomposition of microorganisms reduce the concentration of total pollutants in the leachate, and the evaporation and solid waste 11 (as shown in Figure 3) during the recharge process The interception effect greatly reduces the volume of leachate. The aeration and anaerobic process of the second and third compartments of the regulating tank can further reduce the concentration of pollutants in the leachate.

Early in the operation of this example, no final cover site was available, so early constructed wetland units were built outside the landfill area. As shown in Figure 6, at first the ground is leveled (the slope is 2%), then a 0.2m thick sand diversion layer 26 is laid, and the diameter of the sand is less than or equal to 1cm, and a perforated diversion pipe 27 is laid at intervals of 10m in this layer. Lead out groundwater runoff; the sand diversion layer 26 is overlaid with a 0.2m thick clay layer 25, and is covered with a 1mm thick HDPE anti-seepage membrane sealing layer 20 after leveling. On the membrane are a sandstone layer 24 with a thickness of 0.2m, a filling soil layer 18 and a vegetation layer 17 with a thickness not less than 0.3m, and an outlet pipe 23 is arranged in the sandstone layer 24 . A perforated water distribution pipe 16 about 5m long is arranged at the front end of the constructed wetland unit, and the water distribution pipe is 0.5m higher than the vegetation layer.

After running for a certain period of time in this embodiment, part of the landfill area will be finally covered gradually, and the site of the final cover layer of the landfill site will be directly used to construct the artificial wetland unit. As shown in Figure 5, they are respectively arranged above the garbage layer 22 from bottom to top: Clay layer 21 (1m), HDPE anti-seepage membrane sealing layer 20 (2mm), synthetic material diversion layer 19 (0.3m), fill layer 18 (thickness ≥ 0.3m) and vegetation layer 17 (thickness ≥ 0.3m), A water outlet pipe 23 is provided in the synthetic material guide layer 19 . A perforated water distribution pipe 16 about 5m long is arranged at the front end of the constructed wetland unit, and the water distribution pipe is 0.5m higher than the vegetation layer.

The size of the constructed wetland unit in this example is length×width=30m×15m, the hydraulic retention time of the constructed wetland unit is 6 hours, when the average temperature is higher than 15°C, the hydraulic load is 10L/m ² .d, and the average temperature is 4-15°C , the hydraulic load is 5L/m ² .d, when the average temperature is lower than 4°C or the daily rainfall is 4-15mm, the hydraulic load is 3L/m ² .d, and when the daily rainfall is greater than 15mm, stop watering. In winter, when the wetland plants wither, cover the surface of the constructed wetland unit with a 0.2mm thick polyethylene film.

Plants planted in the vegetation layer of the construction wetland unit in this embodiment are mainly emergent plants such as reeds, water lilies, cannas, yellow bamboo grasses, water onions and rushes. The same plant is planted in the same unit, but different plants need to be planted in different units according to the landscape needs and sewage characteristics, and the plants are harvested regularly.

The water quality index of the final effluent from the constructed wetland in this embodiment has reached the first-level discharge standard of the national "Standards for Pollution Control of Domestic Garbage Landfill Sites" (GB16889-1997).

Example 2

In a landfill site, the effective volume of the regulating pool is 3600m ³ , its size is length×width=60m×25m, and the effective water depth is 3m. Originally, there were 4 Sequencing Batch Activated Sludge Reactors (SBR), which were incorporated into the municipal sewage pipe network after the preliminary treatment reached the third-level discharge standard of the "Pollution Control Standards for Domestic Waste Landfill Sites" (GB16889-1997). Now because the sewage pipe network is rerouted and the cost of merging into the municipal pipe network is too high, the invention is applied to the landfill for separate treatment and discharge after reaching the standard.

In this embodiment, firstly, the adjustment tank is functionally optimized, divided into three compartments, and a function mode of anoxic-aerobic-anoxic is formed by adding corresponding aeration equipment. The first grid size length * width = 36m * 25m, the second and third grid dimensions of the adjustment pool are length * width = 12m * 25m. In the second cell, two submersible aerators are installed for uninterrupted aeration, with a range of 5m and a motor power of 3.7kW. Set up one sludge pump (flow rate: 12.5m ³ /h, lift: 9m, power distribution motor: 0.75kW) at the bottom of the third cell for regular sludge discharge, and set up a lift pump (flow rate: ^12.5m3 /h, lift: 20m, distribution motor power 2kW), the leachate is transported to the SBR reactor.

In this embodiment, a leachate recharge system is added to the newly built landfill area, and the construction method and recharge method are the same as those in Embodiment 1.

In this embodiment, the area of the landfill that has been finally covered is about 20,000 m ² , and the site of the final covering layer of the landfill is directly used to construct the artificial wetland, and the construction method is the same as in Embodiment 1. The effluent of the SBR reactor is used as the influent of the constructed wetland system.

The water quality index of the final effluent from the constructed wetland in this embodiment has reached the first-level discharge standard of the national "Standards for Pollution Control of Domestic Garbage Landfill Sites" (GB16889-1997).

Claims (10)

1, the leachate processing method of a kind of circulated backfilling and artificial swamp coupling is characterized in that may further comprise the steps:

A. make percolate remove bigger suspended substance and the foreign material of part particle diameter through grille well;

B. the percolate with above-mentioned treated mistake concentrates on a part of grains of sand of removal and suspended substance in equalizing tank first lattice;

C. make that a part of percolate recharges to refuse landfill by the leachate recirculation system in above-mentioned equalizing tank first lattice, pouring into artificial wet land system after the pre-treatment of another part through equalizing tank second lattice and equalizing tank the 3rd lattice handles, water outlet back up to standard discharging, the total residence time of sewage in equalizing tank is 15～30 days.

2,, it is characterized in that described percolate recharges to the concrete steps of refuse landfill by the leachate recirculation system and be according to the leachate processing method of described a kind of circulated backfilling of claim 1 and artificial swamp coupling:

1) with the leachate recirculation lift pump percolate in equalizing tank first lattice is promoted to the cloth water plant;

2) will in the percolate in the above-mentioned cloth water plant input inverted well and by the ditch that recharges of inverted well both sides it be recharged to refuse landfill by high density polyethylene pipe;

3) the leachate collection pipeline bottom landfill yard is concentrated to equalizing tank with the percolate of above-mentioned refuse landfill, and recharging frequency is 1～2 time/d, and recharging hydraulic load is 0.01～0.1m ³/ m ².d.

3, according to the leachate processing method of claim 1 or 2 described a kind of circulated backfillings and artificial swamp coupling, it is characterized in that the described equalizing tank second lattice pond at the bottom of the submerged type aerator carry out uninterrupted aeration, separate unit sphere of action 4～8m; The regular spoil disposal of sludge pump that is provided with at the bottom of the 3rd lattice pond, lift pump is delivered to percolate the distributing well of artificial wet land system at the bottom of the 3rd lattice pond.

4, according to the leachate processing method of claim 1 or 2 described a kind of circulated backfillings and artificial swamp coupling, it is characterized in that described artificial wet land system unit hydraulic detention time 6～12 hours; When temperature on average is higher than 15 ℃, hydraulic load 10～15L/m ².d; During 4～15 ℃ of temperature on average, hydraulic load 5～10L/m ².d; When temperature on average is lower than 4 ℃ or when daily rainfall is 4～15mm, hydraulic load 3～5L/m ².d; When daily rainfall during, stop into water greater than 15mm.

5, a kind of percolate treatment facility of realizing the described method of claim 1, it is characterized in that comprising grille well, place grille well equalizing tank, circulated backfilling system and artificial wet land system afterwards, equalizing tank is become three lattice by function optimization, form anoxic-aerobic-anoxybiotic functional mode, establish one of rotary type grid in the grille well, the grille well water outlet directly links to each other with first lattice of equalizing tank.

6, percolate treatment facility according to claim 5, it is characterized in that, the described equalizing tank first lattice useful volume is 60%～80% of the total useful volume of equalizing tank, second lattice are identical with the 3rd lattice useful volume, one of leachate recirculation lift pump is set in first lattice, 1～4 submerged type aerator is set at the bottom of the second lattice pond, one of sludge pump and lift pump is set at the bottom of the 3rd lattice pond.

7, according to claim 5 or 6 described percolate treatment facilities, it is characterized in that, inverted well that described circulated backfilling system comprises the cloth water plant successively, link to each other with the cloth water plant by high density polyethylene pipe and inverted well both sides recharge ditch, every 40～50m inverted well is set, respectively establish one about inverted well and recharge ditch, its structure is: the centre be the perforation water distributing pipe, fill graded broken stone all around, on cover one deck compacting clay.

8, according to claim 5 or 6 described percolate treatment facilities, it is characterized in that, described artificial wet land system is divided into the artificial swamp unit of different shapes and area according to landform with it, connect according to actual needs between unit and the unit and in parallel, the artificial swamp element length is 20～50m, long: wide=1～3: 1, the distributing well water outlet links to each other with the unitary water distributor of artificial swamp, cover the thick polyethylene film of 0.1～0.5mm at the artificial swamp cell surface winter after wetland plant is withered, described wetland plant is an emergent.

9, percolate treatment facility according to claim 8, it is characterized in that, when the artificial swamp unit is positioned at the final tectum of landfill yard, directly utilize the final tectal place of landfill yard to make up the artificial swamp unit, more than waste layer, arrange respectively from bottom to top: clay seam, high density polyethylene(HDPE) anti seepage membrane sealing ply, synthetic materials water conservancy diversion layer, fill stratum, vegetable layer, front end is provided with the perforation water distributor in the artificial swamp unit; When the artificial swamp unit is positioned at beyond the landfill zone, at first carry out smooth to ground, lay sandstone water conservancy diversion layer then, be equipped with the perforation thrust-augmenting nozzle in this layer, cover clay seam on the sandstone water conservancy diversion layer, smooth back covers high density polyethylene(HDPE) anti seepage membrane sealing ply, is followed successively by sand stone layer, fill stratum and vegetable layer on the film, front end is provided with the perforation water distributor in the artificial swamp unit, and the perforation water distributor exceeds vegetable layer.

10, percolate treatment facility according to claim 9, when it is characterized in that described artificial swamp unit is positioned at the final tectum of landfill yard, thickness of clay soil is that 0.2～0.3m, high density polyethylene(HDPE) sealing ply thickness 〉=1mm, synthetic materials water conservancy diversion layer thickness are 0.2～0.3m, fill stratum thickness 〉=0.3m, vegetable layer thickness 〉=0.3m, perforation water distribution pipe range 3～5m, the perforation water distributor exceeds vegetable layer 0.3～0.6m; When described artificial swamp unit is positioned at beyond the landfill zone, the smooth gradient in ground is 1%～2%, sandstone water conservancy diversion layer thickness is 0.2m, and interval 10m lays a perforation water distributor in the sandstone diameter≤1cm, sandstone water conservancy diversion layer, clay bed thickness 0.2m on the sandstone water conservancy diversion layer, high density polyethylene(HDPE) anti seepage membrane sealing bed thickness 1mm, sandstone bed thickness 0.2m on the anti seepage membrane, fill stratum and vegetable layer thickness all are not less than 0.3m, the perforation water distributor is about 3～5m, and the perforation water distributor exceeds vegetable layer 0.3～0.6m.

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