CN111233160B - Modularized non-discharge landfill leachate treatment system and treatment method - Google Patents

Abstract

A modularized non-exhaust landfill leachate treatment system and treatment method, the treatment system includes: a temporary storage pool, a treatment pool, and an emergency pool, wherein a plurality of modular planting boxes are evenly arranged in the treatment pool, and each treatment pool The same number of first plants are planted in the boxes. The first plants in each planting box are plants of the same age. The treatment pool includes N first plants of different ages. The number of first plants of different ages is roughly equal. The age of the first plant is arranged, and further, the planting box also contains a second plant; the treatment system disclosed in the present invention is economical and low-cost, has good treatment effect, is adaptable to various weather environments, has stable treatment capacity, and the treated leachate Internal circulation, without any external emissions. The treatment method is carried out by using the treatment system, and the first plant of the highest age is replaced with the first plant of the youngest age every year, so that a relatively stable treatment capacity can be maintained, so that it does not change greatly with time.

Description

A modular system and method for treating landfill leachate without external discharge

technical field

The invention relates to the field of landfill leachate treatment, in particular to a modularized landfill leachate treatment system and a treatment method without external discharge.

Background technique

At present, the mainstream landfill leachate treatment process at home and abroad is pretreatment + biochemical treatment + membrane system. Pretreatment includes primary pretreatment and secondary pretreatment. Biochemical treatment is mainly MBR process, and membrane system is generally two-stage DTRO, or DTRO+RO. For leachates with lower salinity and poor biodegradability, the MBR process can be omitted. The purification effect of the process system is good, the effluent is stable, and the effluent can meet the standard of Table 2 of the Pollution Control Standard for Domestic Waste Landfills (GB16889-2008). However, this process system has the disadvantage of low water yield. The designed water yield is generally 60% or higher, but with the increase of leachate salinity and other parameters, the water yield is further reduced. On the one hand, in order to overcome the osmotic pressure of up to 2-5MPa, the membrane system needs to consume a lot of electricity. On the other hand, up to 40% of the concentrated liquid needs to be reprocessed by advanced oxidation or low-temperature evaporation and crystallization, which greatly improves the landfill seepage. Overall filtrate disposal cost.

In recent years, the field has also begun to utilize the transpiration of constructed wetlands or plants to treat leachate. Constructed wetlands purify sewage through physical, chemical, and microbial actions, and are a low-cost sewage treatment method. However, the constructed wetland has a small load and weak decontamination ability. It is generally used for leachate treatment of swamp sludge, and it is difficult to treat landfill leachate. Using plant transpiration refers to the use of high transpiration, pollution-resistant, water-loving plants. Through the principle of infiltration and transpiration, the water in the leachate is transferred to the plant body, and evaporated into the atmosphere to achieve the separation of pollutants and water in the leachate, but plant transpiration is greatly affected by weather, such as the eucalyptus experiment in Danzhou Forest Farm, Hainan For the forestry project, the imbalance rate for the whole year of 2016 was above 60%, and the highest was 77.1%. The relevant data are as follows:

Table 1 Evaporation of eucalyptus experimental forest in Danzhou Forest Farm, Hainan in different months in 2016 (L/plant/month)

Tree diameter (cm) Maximum transpiration water consumption (July) Minimum transpiration water consumption (January) Imbalance rate (%) 7.51 45.48 15.96 64.9 9.39 172.86 47.44 72.6 12.45 454.01 103.89 77.1

The unbalanced rate of plant transpiration is high, which causes the current garbage disposal systems using plant transpiration to generally have unstable treatment capacity, which cannot meet the treatment requirements in various periods of the year and under various weather conditions. Therefore, it is urgent to develop a landfill leachate full treatment system with low cost, good treatment effect, stable treatment capacity and no efflux.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a modularized landfill leachate treatment system without external discharge which comprehensively utilizes the principle of constructed wetlands and plant transpiration, aiming at the deficiencies of the landfill leachate treatment device. The technical scheme adopted in the present invention is as follows:

A modular system for treating landfill leachate without external discharge, comprising: a temporary storage pool, a treatment pool, and an emergency pool, the treatment pool is evenly arranged with a plurality of modular planting boxes, and each treatment box is planted with the same number of first plants , the first plants in each planting box are plants of the same age, the treatment pool includes N first plants of different ages, the number of first plants of different ages is roughly equal, and the planting boxes are arranged according to the age of the first plants; The temporary storage pool is communicated with the landfill closure area and/or the landfill recharge area, the temporary storage pool is communicated with the treatment pool and the emergency pool respectively, and the treatment pool is communicated with the landfill closure area and/or landfill recharge areas.

Further, at least one second plant is also planted in each planting box, the number of the second plant is more than that of the first plant, and the second plant is energy grass.

Preferably, the first plant is Acacia acacia and/or eucalyptus, and the second plant is selected from Pennisetum, Elephant Grass, Giant Juncao, Switchgrass, Acacia chinensis, Luzhu, Digi.

Preferably, only one first plant is planted in each planting box, and the number of planting boxes for planting Acacia macrophylla is approximately equal to the number of planting boxes for planting eucalyptus.

Preferably, N is greater than or equal to 5, and the planting boxes are arranged in sequence from front to back according to the water flow direction in the treatment tank according to the age of the first plant; and the planting boxes are arranged in rows from front to back, and the planting boxes in two adjacent rows are staggered. .

Preferably, two coarse and fine gratings and a trash net are arranged at the entrance of the temporary storage tank, the treatment tank is provided with an overflow port, and the treatment tank is connected to the emergency tank through the overflow port.

Preferably, the bottom and sides of the treatment tank are provided with an impermeable layer, and the impermeable layer includes a sand and stone layer, a clay layer, a polyethylene film layer, and a clay layer, and the treatment tank includes a water distribution pipe and a water collection pipe. Both the water pipe and the collecting pipe are porous pipes.

Preferably, the treatment tank is provided with a movable rainproof shed, and the movable rainproof shed is provided with a circular gap corresponding to the number of the first plants.

Preferably, the planting box is in the structure of a round barrel or a square barrel, surrounded by hollow plates, the bottom surface is a sealing plate, the upper part of the planting box is provided with hooks for hanging, the height of the planting box is higher than the height of the treatment tank, and the substrate in the planting box is Includes fine sand, gravel, zeolite, biochar, soil.

The present invention also protects a method for treating leachate without efflux, using the treatment system of the present invention, wherein the N ages of the first plant are increased by 1 in order from small to large, and it is characterized in that the following steps are adopted:

(1) Lead the leachate from the closed area of the landfill and/or the recharge area of the landfill into the temporary storage tank;

(2) Introduce a large amount of leachate from the temporary storage tank into the treatment tank to ensure the water saturation of the planting box;

(3) Strictly control the inflow of the treatment pool according to the processing capacity of the treatment pool. When the temporary storage pool reaches the upper limit of the water level, the leachate exceeding the upper limit of the water level in the temporary storage pool shall be introduced into the emergency pool;

(4) Introduce the treated leachate from the treatment tank to the recharge area of the landfill;

(5) From the second year when the treatment system is put into use, remove the oldest first plant and planting substrate every year, refill the substrate after drying and thermal desorption, and replace the same number of N species with the youngest age. , and restore the planting box to its original state according to the distribution of the first plant age.

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

1. Combining artificial wetlands and plant transpiration for landfill leachate treatment, which not only improves the treatment effect, but also reduces the cost of the treatment system;

2. The modular planting box is set in the treatment tank, even if the user arranges the plants according to their needs, it also solves the problem that the plants and the substrate are not easy to replace;

3. By planting different numbers and proportions of plants of different ages, and in combination with plant arrangement, flow control, substrate moisture saturation, rain protection and other measures, the relative balance of total transpiration in different seasons, weather, day and night conditions is maintained to ensure the system The leachate treatment effect is stable for a long time;

4. Regularly replace the oldest plants with a total number of 1/N with new younger plants with a total number of 1/N every year to maintain a stable transpiration and ensure that the leachate treatment capacity of the system does not change significantly with time.

Description of drawings

Fig. 1 is the overall schematic diagram of the processing system in the present invention;

Fig. 2 is the structural representation of processing tank in the present invention;

FIG. 3 is a schematic diagram of the arrangement of a planting box in a treatment tank in a specific embodiment of the present invention.

Detailed ways

The modularized non-exhaust landfill leachate treatment system of the invention belongs to the field of landfill leachate treatment, and comprehensively utilizes the principle of constructed wetlands and plant transpiration. The present invention will be further described below with reference to the accompanying drawings. It should be specially pointed out that the terms "vertical", "horizontal", "front", "rear", "upper", "lower", etc. used therein indicate that the orientation and positional relationship are based on the orientation shown in the drawings or The positional relationship is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the indicated device or element must have a specific orientation, be constructed and operated in a specific orientation, and should not be construed as limiting the specific protection scope of the present invention.

It is understood with reference to FIG. 1 that the treatment system is used in a general landfill, and the landfill includes a landfill closure area 4, which usually means that the garbage in the landfill has been fully landfilled and will no longer be landfilled. It is the main source of landfill leachate; it can also include the landfill recharge area 5, which is used to receive the liquid returned from the treatment system and input the regenerated leachate into the treatment system. Under normal circumstances, there is no strict boundary between the recharge area of the landfill and other areas of the landfill. The leachate after recharge and the original leachate in the closed area of the landfill may be mixed together and re-entered. processing system.

The treatment system includes: temporary storage pool 1, treatment pool 2, emergency pool 3, temporary storage pool 1, treatment pool 2, emergency pool 3, landfill closure area 4 and/or landfill recharge area 5. Pipes, valves and pumps can be set up in each room; the temporary storage pool 1 is communicated with the landfill closing area 4 and/or the landfill recharge area 5, and is used for temporarily storing the seepage from the landfill. Filtrate; the temporary storage pool 1 is connected with the treatment pool 2 and the emergency pool 3 respectively, and the flow into the treatment pool 2 is controlled through a valve to prevent the leachate flowing into the treatment pool 2 from exceeding the processing capacity of the treatment pool 2; the described The temporary storage pool 1 is communicated with the emergency pool 3. When the temporary storage pool 1 reaches the upper limit of the water level, the leachate is introduced into the emergency pool 3, and when conditions permit, the leachate is returned to the temporary storage pool 1; the treatment pool 2 Connected to the landfill closure area 4 and/or the landfill recharge area 5, all the leachate treated in the treatment tank 2 returns and re-enters the treatment system, truly realizing no efflux of the leachate.

The structure of the treatment tank 2 can be understood in conjunction with FIG. 2. The treatment tank 2 is evenly arranged with a plurality of modular planting boxes 6, and each treatment box 6 grows the same number of first plants 8 and 9. Through the transpiration principle of plants, a large number of Reduce leachate and evaporate only pure water to separate pollutants from water. The first plants 8 and 9 in each planting box are plants of the same age. The treatment tank includes N kinds of first plants 8 and 9 of different ages. The number of first plants of different ages is approximately equal. age arrangement. Preferably, the N ages of the first plant are incremented by 1 in order, such as young age (new saplings less than one year old), first age, second age...N age, in order to maintain better processing capacity, it is more preferable Yes, the plan is to choose the minimum age of the first plant to select three or four ages, such as: three ages, four ages, five ages...N+3 ages.

The planting box 6 can adopt a round barrel structure or a square barrel structure, surrounded by hollow plates to facilitate the passage of leachate, and the bottom surface is a sealing plate. The rupture of the anti-seepage layer leads to the problem of leachate extravasation; on the other hand, it promotes the even flow of leachate in the treatment tank. The upper part of the planting box is also provided with hooks for lifting, which is convenient for removing or loading the planting box from the treatment tank.

The planting box 6 adopts the above modular design, which is more convenient for the user to arrange the planting box 6 in the treatment tank according to the design scheme, and also facilitates the removal or replacement of the plants and substrates in the planting box 6 .

In the present invention, the first plant is preferably Acacia grandis 8 and/or Eucalyptus 9, Acacia grandis 8 has fast growth speed, strong adaptability and wide application; Eucalyptus 9 has a high trunk, developed root system and great transpiration effect; it is possible to plant only one Planting plants, or two kinds of plants can be planted at the same time. It is preferred to cross plant two kinds of plants. Different plants have different transpiration amounts in different seasons, weather, day and night, etc. Growth characteristics, play their respective advantages, and maintain the relative balance of total transpiration in different seasons, weather, day and night.

In order to comprehensively utilize the principle of artificial wetland, at least one second plant 10 is also planted in each planting box 6, and the number of the second plant 10 is more than that of the first plants 8 and 9, and the second plant 10 is Pennisetum, elephant Grass, juncao, switchgrass, grass reed, reed bamboo, Digum, etc., generally belong to the scope of energy grass, which can form artificial wetlands and supplement the leachate treated by plant transpiration.

Preferably, only one first plant 8, 9 is planted in each planting box 6, and further, in the case of planting Acacia macrophylla and/or eucalyptus, the number of planting boxes 6 for planting Acacia macrophylla 8 is the same as that for planting eucalyptus 9 The number of planting boxes 6 is approximately equal.

Preferably, N is greater than or equal to 5, and the planting boxes 6 are arranged in order from front to back according to the age of the first plants 8 and 9 according to the water flow direction in the treatment tank; Acacia 8 and eucalyptus 9 are alternately arranged, and the planting boxes in two adjacent rows are arranged in a staggered manner. As shown in Figure 3, the planting box 6 in the latter row is arranged at the rear of the interval between the two planting boxes 6 in the previous row, which can be more comprehensive. , Treat the leachate without dead ends. It should be noted that FIG. 3 is only a schematic diagram showing the arrangement of some of the planting boxes 6 in the treatment tank 2 , and the planting boxes 6 of other parts are arranged in a similar manner.

Specifically, in order to remove the larger impurities in the leachate flowing out from the landfill closure area and/or the landfill recharge area, so as to avoid clogging the treatment tank, coarse and fine grids are installed at the entrance of the temporary storage tank. In addition, considering that under extreme conditions such as rainstorms and floods, the water in the treatment pool may overflow and cause pollution to the surroundings, the treatment pool in the present invention is provided with an overflow port, and the treatment pool is connected through the overflow port. emergency pool.

In order to prevent the leachate in the treatment tank 2 from polluting the soil and groundwater outside the treatment system, the bottom and side surfaces of the treatment tank 2 are provided with an anti-seepage layer 11, and the anti-seepage layer 11 includes a sand and stone layer, a clay layer, and a polyethylene film. layer, clay layer.

In order to introduce the leachate into the treatment tank 2 more uniformly and collect the treated leachate more fully, the treatment tank 2 includes a water distribution pipe and a water collection pipe, both of which are porous pipes.

In order to minimize the impact of rainstorm, heavy snow, hail and other weather on the treatment pool, the treatment pool 2 is provided with a movable rain shelter 7, and the movable rain shelter 7 is provided with a circular gap corresponding to the number of the first plants. The movable rain shelter 7 is a continuous W shape in the horizontal direction, with a plurality of flexible circular gaps reserved at the highest point, and the positions of the multiple flexible circular holes are the diameter of the Acacia acacia tree or the tree diameter of the eucalyptus; the movable rain shelter is arched in the longitudinal direction. , the center of the treatment pool is the highest, and the two sides of the treatment pool are the lowest; the top of the movable rain shelter 7 is not higher than the canopy of the Acacia acacia and the canopy of the eucalyptus. Rainwater drainage ditches 12 are arranged around the treatment tank to drain the rainwater collected by the movable rainproof shed 7 in time.

According to the present invention, technicians can determine the number of planting boxes 6 according to the amount of leachate to be treated and the transpiration amount of the planted plants; the size and arrangement spacing of the planting boxes are determined according to the planted plants. The size of the planting box is preferably: 1.3-1.5 meters in diameter, 2-2.5 meters in height, and the spacing between the planting boxes is 0.2-0.4 meters; the filling matrix in the planting box preferably includes fine sand, gravel, zeolite, biochar, soil and other components . In the process of use, the moisture content of the substrate in the planting box should be in a saturated state as much as possible to reduce the influence of the moisture content of the substrate on the transpiration and maintain a relatively stable processing capacity.

For the specific design of the treatment tank 2, the specific area of the treatment tank 2 can be determined according to the amount of leachate treated and the size and spacing of the planting box; , to ensure that the plant root system will not be completely immersed in water and immersed to death; in addition, in order to realize the natural flow of leachate in the treatment tank 2, a hydraulic gradient is set in the treatment tank 2, and the hydraulic gradient is based on the amount of leachate treated and the area of the treatment tank. OK, control between 0.5%-1%.

The invention also discloses a method for treating leachate without efflux, using the treatment system of the invention, wherein the N ages of the first plants are increased by 1 in order from small to large, and the following steps are specifically adopted:

(1) Introduce the leachate from the landfill closure area 4 and/or the landfill recharge area 5 into the temporary storage tank 1;

(2) A large amount of leachate from the temporary storage tank 1 is introduced into the treatment tank 2 to ensure that the water in the planting box 6 is saturated, so as to minimize the influence of the water content of the matrix on the unbalance rate;

(3) Strictly control the inflow of the treatment pool according to the processing capacity of the treatment pool 2. When the temporary storage pool reaches the upper limit of the water level, the leachate exceeding the upper limit of the water level in the temporary storage pool 1 shall be introduced into the emergency pool 3; After the water level returns to normal, the leachate from the emergency pool 3 is led back to the temporary storage pool 1;

(4) The leachate treated in the treatment tank 2 is introduced into the recharge area 5 of the landfill;

(5) From the second year when the treatment system is put into use, remove the oldest first plant every year, and replace the same number of N species with the youngest first plant.

Generally, in the process of removing the first plant, other plants (second plants) in the same planting box should also be removed and replaced, and the matrix in the planting box should be dried and thermally desorbed, and then refilled in the planting box. 6. In order to ensure the processing capacity of the planting box 6 and the treatment tank 2 after replacement as much as possible, through drying and thermal desorption of the matrix, the problem that the organic pollutants in the matrix are difficult to degrade can also be solved.

In addition, in the event of sudden heavy rain, heavy snow, hail and other extreme weather phenomena, the movable canopy 7 should be propped up in time to expose the canopy of the first plant from the flexible circular gap.

By utilizing two principles of artificial wetland and plant transpiration, the present invention effectively improves the removal ability of the system; , Digi and other different types of plants, as well as 5 first plants of different ages, planting different plant numbers in proportion, and maintaining the moisture saturation state of the lower half of the substrate in the planting box can effectively reduce the processing capacity of the system between months. imbalance rate.

Take a domestic waste landfill in Guangdong as an example to prove the implementation effect of the present invention:

In a domestic waste landfill in Guangdong, the total capacity of the landfill is 3 million cubic meters, and the system according to the present invention is constructed for the treatment of part of the leachate.

The system includes: a temporary storage pool, a treatment pool, an emergency pool, a landfill recharge area, a landfill closure area, and related pipelines, valves, and pump groups; the temporary storage pool, the landfill closure area, and the / or the landfill recharge area is connected, the temporary storage pool is connected with the treatment pool and the emergency pool respectively, and the flow into the treatment pool is controlled by a valve, the temporary storage pool is connected with the emergency pool, and the temporary storage pool reaches the When the water level reaches the upper limit, the leachate is introduced into the emergency pool, and when conditions permit, the leachate is returned to the temporary storage pool; the treatment pool is connected to the landfill closure area and/or the landfill recharge area, and the treatment pool treats the All the leachate is returned and re-entered the treatment system, which truly realizes no efflux of leachate.

The temporary storage pool is the existing temporary storage pool in the landfill, with a volume of 1,000 cubic meters; the emergency pool is an existing emergency pool in the landfill, with a volume of 3,000 cubic meters, which is used to balance changes in transpiration in different seasons, weather, day and night, and respond to Other emergencies; two thick and thin gratings and a trash net have been set up at the entrance of the temporary storage pool.

The width of the treatment tank is 10.75m, the length is 114m, the depth of the treatment tank is 1.0m, and the hydraulic gradient is 0.5%.

In order to prevent the leachate from generating dead ends and swirls in the treatment tank and maintain the uniform flow of the leachate, the water distribution pipe and the water supply pipe of the treatment tank are porous PVC pipes, and the total length of the water distribution pipe and the water supply pipe is 10.75m respectively.

The bottom and sides of the treatment tank are provided with anti-seepage layers. The bottom anti-seepage layer is from bottom to top, and the side anti-seepage layer is composed of sandstone layer, clay layer, polyethylene film layer and clay layer from outside to inside.

The planting boxes in the treatment tank are arranged according to 5 rows in each row, for a total of 60 rows, and 300 planting boxes are evenly arranged staggered in front and back.

The spacing of the planting boxes in the treatment tank is 0.3 meters. The planting box is welded with steel bars to form a barrel structure. The surrounding is lined with plastic hollow boards. The bottom surface is a sealing plate. It is 2.0 meters, and there are also reserved spaces for movable rain shelters, water distribution pipes, and water collection pipes in the treatment box.

The planting box is filled with a matrix, which consists of 5-10mm fine sand, 10-15mm gravel, zeolite, biochar, and soil. The volume ratio of fine sand, gravel, zeolite, and soil is 1:1. Biochar is made of biomass heat. It is prepared by degasification process, and the addition ratio is 5% of the total volume of the matrix.

From the water inlet direction of the treatment tank, in the first 12 rows of planting boxes, each planting box is planted with a 3-year-old Acacia tree or a 3-year-old eucalyptus tree, and a total of 30 3-year-old Acacia trees are planted alternately. and 30 3-year-old eucalyptus trees; in the planting boxes in rows 13-24, one 4-year-old Acacia tree or one 4-year-old eucalyptus tree is planted at intervals in each planting box, and a total of 30 4-year-old eucalyptus trees are planted alternately. Acacia leaves and 30 4-year-old eucalyptus trees; in the planting boxes in rows 25-36, 5-year-old acacia or 5-year-old eucalyptus trees are planted at intervals in each planting box, and a total of 30 5-year-old eucalyptus trees are planted alternately. Acacia and 30 5-year-old eucalyptus trees; in the planting boxes in rows 37-48, 6-year-old Acacia trees or 6-year-old eucalyptus trees are planted at intervals in each planting box, and a total of 30 6-year-old Acacia trees are planted alternately Trees and 30 6-year-old eucalyptus trees; in the planting boxes in rows 49-60, each planting box is planted with 7-year-old Acacia or 7-year-old eucalyptus, and a total of 30 7-year-old Acacia trees are planted alternately and 30 7-year-old eucalyptus trees.

In each planting box, acacia or eucalyptus is located in the center of each planting box, surrounding the acacia or eucalyptus, each planting box is roughly divided into three 1/3 circle fan-shaped areas, which are evenly planted respectively. 10 Pennisetum, 10 Giant Juncao, 10 Elephant Grass.

In order to reduce the amount of leachate produced in the landfill, Acacia acacia, eucalyptus, as well as Pennisetum, Elephant grass, Giant Juncao and other plants are also planted in the closed area of the landfill.

Rainwater drainage ditches are arranged around the treatment tank to drain the rainwater around the treatment tank in time to prevent the overflow of the leachate in the treatment tank and prevent the external rainwater from being poured into the treatment tank uncontrollably.

After the movable rain shelter in the treatment tank is combined, it is a continuous W shape in the horizontal direction, and 300 flexible circular gaps are reserved at the highest point. tree path. The movable rain shelter is arched as a whole in the longitudinal direction. The center of the treatment pool is 1.8 meters high, and the two sides of the treatment pool are the lowest and connected to the rainwater drainage ditch. During operation, the movable rain shelter is closed when it is sunny; the movable rain shelter is opened in rainy weather, and the rainwater is collected by the rain shelter and discharged from the rainwater drainage ditch around the treatment tank.

Taking the data of 2018 as an example, the annual average rainfall of the landfill is 1623.6-1899.8mm, the annual sunshine hours are 1770-1940 hours, and the annual total radiation amount is 4400-5000MJ/m ² . The annual average parameters of leachate detected in the temporary storage pool are: CODcr 9.1g/L, BOD5 2.6g/L, SS 4.0g/L, TN 3.4g/L, NH3-N 2.2g/L, TP 24.8mg/L L, conductivity 29900 μs/cm, pH 7.4.

When the system is running, the treatment tank first injects a large amount of leachate to ensure the water saturation of the planting box, and then strictly controls the inflow of the treatment tank (after deducting the effect of rainwater) according to the evaporation of the treatment tank to prevent the overflow of the leachate.

In 2018, the inflow of the treatment pool was 3227.4 tons, and the average evaporation was 8.84 tons per day. Deducting the dead 17 acacia and eucalyptus, according to the remaining 283 acacia and eucalyptus, the average evapotranspiration load per plant is 31.24kg/day (including the contribution of the second plant). According to the area of the treatment tank, the average evaporation load is 7.215kg/m2/day. According to the data in Table 1, the highest daily average treatment (evaporation) in July was 9.6t/day, and the lowest in March was 8.06t/day, with an imbalance rate of 16.04%, much lower than the eucalyptus itself. Unbalance rate.

Table 2 The daily average leachate treatment volume (t/d) in different months of the treatment tank for one year (January-December 2018)

January February March April May June July August September October November December Maximum unbalance rate (%)) inflow 8.45 8.63 8.06 8.36 9.13 9.43 9.60 9.47 9.27 8.83 8.43 8.37 16.04

From the second year after the system is put into use, the planter boxes that have reached 8 years of age are replaced every March. Remove the movable awning, cut the plant roots between the various planting boxes with a chainsaw, and lift the planting boxes out of the treatment tank with a crane. After a large amount of water naturally flows out, it is placed on the cement floor. Acacia, Eucalyptus, as well as Pennisetum, Elephant Grass, Giant Juncao, remove the root system. After the substrate is dried and thermally desorbed, it is reloaded into the planting box, and the 3-year-old Acacia, 3-year-old eucalyptus, as well as Pennisetum, Elephant grass and Giant Juncao are replanted, and then put into the treatment by a crane In the pond, adjust the position of the planting boxes row by row, restore the original arrangement according to the age in the treatment pond, ensure that the processing capacity of the system does not decrease with time, and thoroughly treat the difficult-to-degrade pollutants in the substrate.

The above embodiment comprehensively utilizes the principles of artificial wetlands and plant transpiration, the treatment effect is good, the comprehensive cost is low, the unbalance rate of evaporation treatment capacity is low in various periods of the year and under various weather conditions, and the treatment capacity is stable. It is an ideal landfill leachate treatment method by completely removing the residual pollutants with the substrate and making the treatment capacity not change greatly with time.

While the invention has been described in terms of specific embodiments, it will be apparent to those skilled in the art that the invention can be modified in other ways in light of the teachings herein. The protection scope of the present invention is limited by the scope of the claims, but other technical solutions that are not substantially different from the claims of the present invention should also be within the protection scope of the present invention.

Claims (5)

1. A modular system for treating landfill leachate without external discharge, comprising: a temporary storage pool, a treatment pool, and an emergency pool, characterized in that: the treatment pool is evenly arranged with a plurality of modular planting boxes, and each planting box is planted The same number of first plants, the first plants in each planting box are plants of the same age, the treatment pool includes N first plants of different ages, the number of first plants of different ages is equal, and the first plants in the planting box are the same as the first plants. The said temporary storage pool is connected with the landfill closing area and/or the landfill recharge area, the said temporary storage pool is connected with the treatment pool and the emergency pool respectively, and the described treatment pool is connected with the filling area. Landfill closure areas and/or landfill recharge areas; N is greater than or equal to 5, the planting boxes are arranged in sequence from front to back according to the water flow direction in the treatment tank according to the age of the first plant; and the planting boxes are arranged in rows from front to back, and the planting boxes in two adjacent rows are staggered; The treatment system is used for the treatment of landfill leachate without efflux, wherein the ages of the N species of the first plants are increased by 1 in order from small to large, and the following steps are adopted: Lead the leachate from the landfill closure area and/or the landfill recharge area to the temporary storage tank; Introduce a large amount of leachate from the temporary storage tank into the treatment tank to ensure that the water in the planting box is saturated; Strictly control the inflow of the treatment pool according to the treatment capacity of the treatment pool. When the temporary storage pool reaches the upper limit of the water level, the leachate exceeding the upper limit of the water level in the temporary storage pool will be introduced into the emergency pool; The leachate treated by the treatment tank is introduced into the recharge area of the landfill; From the second year when the treatment system is put into use, remove the oldest first plant and the planting substrate every year, refill the substrate after drying and thermal desorption, and replace the same number of N species with the youngest first plant. Plant, and restore the planting box to its original state according to the distribution pattern of the first plant age; At least one second plant is also planted in each planting box, and the number of the second plant is more than that of the first plant; The first plant is Acacia grandis and/or eucalyptus, and the second plant is selected from Pennisetum, Elephant Grass, Giant Juncao, Switchgrass, Acacia chinensis, Reed Bamboo, Digi. 2. The processing system as claimed in claim 1: two gratings, two grids and one trash net are set at the entrance of the temporary storage tank, the processing tank is provided with an overflow port, and the processing tank is connected to the emergency through the overflow port. pool. 3. treatment system as claimed in claim 2: the bottom and the side of the described treatment tank are all provided with an impermeable layer, the bottom impermeable layer is from bottom to up, and the side impermeable layer is successively followed by the sandstone layer from the outside to the inside. , a clay layer, a polyethylene film layer, and a clay layer; the treatment tank includes a water distribution pipe and a water collection pipe, and both the water distribution pipe and the water collection pipe are porous pipes. 4. The treatment system according to claim 3: the treatment tank is provided with a movable rainproof shed, and the movable rainproof shed is provided with a circular gap corresponding to the number of the first plants. 5. The processing system according to claim 1: the planting box is of a round or square barrel structure, surrounded by hollow plates, the bottom surface is a sealing plate, the upper part of the planting box is provided with hooks for hanging, and the height of the planting box is high. At the height of the treatment tank, the substrate in the planting box is composed of fine sand, gravel, zeolite, biochar, and soil.

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