CN211813686U - A graded ecological treatment system for treating rural domestic sewage and rainwater - Google Patents

Abstract

The utility model discloses a grading ecological treatment system for treating rural domestic sewage and rain sewage, which is suitable for various rain and sewage confluence systems in rural areas for sewage drainage ditches or open spaces. The ecological treatment system is divided into first-level and second-level. The first-level ecological treatment system consists of the first-level LID new ecological ditches or ecological gardens and reservoirs, and the effluent quality is the standard for farmland irrigation. The secondary ecological treatment system is composed of the primary ecological treatment system and the secondary LID new ecological ditches or ecological gardens, and its effluent quality is Grade A. The vertical structure of the first-level and second-level LID new ecological ditches or ecological gardens includes, from top to bottom, an aquifer that stores early rainwater runoff, a composite filter layer for planting woody plants, and an anti-seepage layer. The utility model has multiple functions of "infiltration, storage, stagnation, purification and drainage", which can not only control the rural domestic sewage and rainwater problems, but also beautify the environment and realize the coordination and unity of pollution control, water control and ecological environment construction.

Description

A graded ecological treatment system for treating rural domestic sewage and rainwater

technical field

The utility model belongs to the technical fields of water conservancy engineering, municipal engineering and environmental engineering, in particular to a graded ecological treatment system for treating rural domestic sewage and rainwater.

Background technique

Rural domestic sewage is usually discharged directly into the receiving water body through the large and small sewage ditches in the village. The traditional rural sewage ditches, also known as stinky water ditches, are not only dirty and smelly, but also the domestic sewage containing a large amount of pollutants passes directly through without treatment. The stinky ditch is discharged into the receiving water body, which will also greatly pollute the water environment.

In order to treat rural domestic sewage, more and more rural areas have followed the practice of urban rain and sewage diversion, abandoning the existing sewage ditches in rural areas and building new pipe networks for sewage collection. However, simply imitating the practice of urban rain and sewage diversion in rural areas will actually bring some problems. Specifically, some earth ditches in rural areas normally discharge sewage, but in rainy days, they discharge both sewage and rainwater runoff. The ditches can maintain a good water delivery function due to the flow of water all year round. However, with the newly built sewage pipe network in rural areas for sewage treatment, the soil ditches have become special channels for discharging rainwater runoff. Since there is no sewage flow in the soil ditches on weekdays, grass seeds can easily fall to the soil ditches with the wind and take root, and the soil ditches gradually change. In the deserted land full of weeds, it is difficult for these soil ditches to discharge rainwater runoff during heavy rains during the flood season, resulting in flooding of the village. Furthermore, some existing research results show that the pollution level of initial rainwater runoff is even more serious than that of domestic sewage. For example, the COD value of initial rainwater runoff in a residential and commercial area in the upper reaches of the Dongjiang River in Guangdong Province reached a maximum of 1136 mg/L. The maximum COD value of the initial rainwater runoff in the market reached 1450mg/L, which is 5 to 7 times the COD value of the typical domestic sewage discharged from PVC pipes. Although the survey results of the initial rainwater runoff water quality in rural areas are rarely reported, but in rural areas, chickens and ducks are usually kept free-range, and various rotten vegetables are piled up. more serious. The purpose of rainwater and sewage diversion is to ensure that sewage treatment facilities with limited tonnage can be designed to handle large and small, that is, to seize the most polluting rural domestic sewage for treatment, and ignore the less polluting rainwater runoff for direct discharge. But in fact, compared with rural domestic sewage, the initial rainwater runoff in rural areas is a larger source of pollution.

In addition, at present, many rural decentralized sewage treatment facilities simply apply the dynamic treatment processes such as AO, A ² O, and MBR that are often used in urban sewage treatment plants. This not only brings about the problem of future operation costs, but also brings many problems because the facilities are scattered all over the countryside, and it is difficult for the inspectors to supervise the operation around the clock in the vast rural areas. For example, power outages often occur in rural areas, and the maintenance unit cannot restore the power supply of the facilities in time by using intermittent facility inspections, resulting in the easy outage of aerobic pools, facultative oxygen pools and MBR pools. Over time, aerobic bacteria and facultative oxygen The bacteria died one after another, and it was difficult for the flora to resume normal growth immediately after the power was re-powered.

On the other hand, in September 2018, the Ministry of Ecology and Environment and the Ministry of Housing and Urban-Rural Development jointly issued the "Notice on Accelerating the Development of Local Rural Domestic Sewage Treatment and Discharge Standards". and tail water recycling. And farmland irrigation is a very suitable way of sewage recycling in rural areas. In July 2019, nine departments including the Ministry of Water Resources jointly issued the "Guiding Opinions on Promoting the Treatment of Rural Domestic Sewage". Therefore, in view of the shortcomings of the simple application of urban pollution control methods in the current rural sewage treatment work, it is extremely necessary to explore new pollution control strategies that conform to the spirit of the above notices and opinions.

In this context, we have developed "a graded ecological treatment system for rural domestic sewage and rainwater". The utility model patent transforms the traditional stinky water ditch or wasteland and open land in rural areas into a new LID ecological ditch/garden that combines the functions of ecological landscape and "infiltration, storage, purification, utilization and drainage", so that sewage flows into the ecological ditch/garden. After the garden, it can be discharged while purifying. The rural domestic sewage ecological treatment system using LID new ecological ditches/gardens consists of first-level LID new ecological ditches/gardens, reservoirs, second-level LID new ecological ditches/gardens, and diffusion and seepage system (optional). Rural domestic sewage flows into the first-level LID new ecological ditches/gardens. After infiltration and purification, it reaches the farmland irrigation standard, then flows into the reservoir, and is reused for farmland irrigation through the farmland irrigation system. The residual water flows into the second-level through the overflow of the reservoir. LID's new ecological ditches/gardens, after further infiltration and purification, reach the first-level A discharge standard, or directly discharge into the receiving water body, or learn from the decentralized treatment method of rural domestic sewage in the United States, and penetrate into the soil through a buried diffusion and seepage system. Recharge groundwater and form a good ecological cycle. The system can not only treat rural domestic sewage, but also treat rainwater non-point source pollution and reduce stormwater runoff. In addition, planting water-resistant and pollution-resistant woody plants in the ditches can also beautify the surrounding environment, so as to highly coordinate and unify the pollution control, water control and ecological landscape construction, and effectively promote the construction of beautiful villages.

One of the core technologies of the utility model patent lies in the use of woody plants rather than herbs that are moisture-resistant and stain-resistant and have good purification ability. Herbs are not suitable for extensive management and are not suitable for use in rural areas. After the novelty investigation, no research has been found to carry out the research on moisture resistance and pollution resistance of woody plants at the same time, and no research has been carried out on the three kinds of humidity resistance, pollution resistance and purification ability of woody plants at the same time. After 3 years of plant experimental research, we have selected several species of southern woody plants that are suitable for planting in LID-type ecological ditches/gardens. The second core technology of the utility model patent is to select the appropriate filter material according to the different water quality standards of the first-level and second-level LID new sewage ditches/gardens. The effluent quality standard of the first-level LID new sewage ditches/gardens is the standard of farmland irrigation, and nutrients such as nitrogen and phosphorus are required by plants. Therefore, the filter material selected for the first-level LID new sewage ditches/gardens is the same as the second-level LID new sewage ditches. The filter media is completely different. The characteristics of the first-grade filter media are that they have a high removal rate of organic pollutants, and the lower the removal rate of nitrogen and phosphorus nutrients, the better. The secondary filter material needs to have a good removal rate of organic pollutants and nitrogen and phosphorus nutrients at the same time. After 3 years of experimental research, we have developed a secondary composite filter material composed of several matrices. The results of novelty search show that there are no relevant reports yet.

Although a series of ecological treatment technology facilities such as artificial fast infiltration system, soil infiltration system, and vertical subsurface artificial wetland can treat rural domestic sewage. However, these facilities have the following disadvantages:

1) The technical measures cannot be directly constructed on the stinky water ditches in rural areas, and additional land is required for construction.

2) The plants used are all herbs, which are not suitable for extensive management and are difficult to be applied in rural areas. Many of these ecological treatment facilities using herbs have been in operation in rural areas for a period of time and have been abandoned due to high maintenance costs. Secondly, if herbs are planted in ecological ditches, in rainy days, the dense herb plants in the ditches will greatly affect the flood discharge of the ditches.

2) The filter material layer of these traditional facilities is usually composed of various substrates such as zeolite, iron particles, volcanic rock, shell rock, limestone, activated carbon, wheat straw, slag, activated ceramsite, etc., which lacks the need to combine farmland irrigation and reuse. , Based on the concept of graded purification, the selection of filter materials is carried out. The filter materials used are usually combined with several substrates to remove a large amount of nitrogen and phosphorus required by crops, that is, the cost of filter materials is wasted and the nutrients in sewage are wasted. resource.

3) The structure of these traditional facilities generally adopts the following layered structure: generally divided into a planting soil layer, a water distribution layer is laid under the soil layer, and a filter material layer is laid under the water distribution layer. This layer structure brings the following problems: the plants in the planting soil layer are usually amphibious plants such as turf, canna, iris, cattail, etc. The roots of these plants are relatively shallow, and they are mainly distributed in the soil layer. The material layer is especially difficult to penetrate into the middle and lower parts of the filter material layer. Therefore, plants cannot absorb nitrogen, phosphorus and other nutrients adsorbed by the filter material layer, especially the middle and lower parts of the filter material layer, and cannot transfer these nutrients to the outside world in time, that is, transform them into stems, leaves and flowers of plants. As a result, nutrients such as nitrogen and phosphorus in sewage continue to enter, and the way to transfer to the outside world is limited. Only the action of some soil microorganisms, especially phosphorus, lacks a way to transfer to the outside world. Therefore, after the facility has been running for a period of time, The adsorption effect of the filter material will reach saturation, which brings about the problems that the filter material needs to be replaced regularly and the operation and maintenance management is not easy.

4) Existing treatment facilities such as artificial fast infiltration systems, soil infiltration systems, and vertical underflow artificial wetlands with the uppermost layer of the planting soil layer structure, due to the limited infiltration capacity of the soil layer, a large amount of water flows into the facility in case of heavy rain. It is also difficult to quickly infiltrate the rainwater runoff into the filter material layer for purification, and the initial rainwater runoff containing a large amount of pollutants cannot be treated and most of it flows away directly. Therefore, it can only be used for domestic sewage treatment, and cannot play a dual role, that is, to treat domestic sewage on weekdays, and to effectively treat initial rainwater runoff with a large amount of pollutants in rainy days.

6) The existing artificial fast infiltration system, soil infiltration system, vertical underflow artificial wetland and other treatment facilities usually use planting herbs on the planting soil layer. If these technical measures are directly applied to rural sewage ditches, the herbs will come It is not easy to maintain and manage, and it is not suitable for use in rural areas. Second, when there is heavy rain, these low herbaceous plants will seriously hinder the flooding of ditches.

In order to solve the above-mentioned drawbacks existing in a series of ecological treatment technical facilities such as the existing artificial fast infiltration system, soil infiltration system, and vertical underflow artificial wetland, we have developed the utility model.

For all existing patents and protected technical data inquiries, there are currently 4 patents or patent applications that are closest to this utility model:

The first patent is Chinese invention patent application number 200620003976.5, application date 2006.2.15, authorization announcement number CN 2866592Y, authorization announcement date 2007.2.7, patent name: trench type wetland bed. The patent builds the ditch into a wetland to reduce soil erosion and rainwater pollutants. The main disadvantages are: 1) First of all, the treatment object of this patent is rainwater, so it is not suitable for the treatment of rural domestic sewage. 2) Even if it is applied to the ditch that only discharges rainwater, it is not suitable for the drainage ditch with large drainage volume and fast drainage speed. First, the soil medium on the wetland surface is easily washed away during the rainstorm when the drainage volume is large and the flow velocity is fast; Plants shuttle between each other and suffer from high resistance, which makes it difficult to drain water smoothly, and it is easy to cause stagnant water to overflow the wetland bed.

The second patent is Chinese invention patent application number CN201310555523.8, application date 2013.11.11, announcement number CN 103603320A, announcement date 2014.2.26, patent name is "a LID type rainwater ditch and its design calculation method", the patent It is proposed for the rainwater problem and cannot be applied to the treatment of rural domestic sewage.

The third patent is the Chinese invention patent application number 201610016399.1, application date 2016.01.11, publication number CN105621797A, and the patent name is "Utilizing idle ditches and farmland to treat sewage". Although this patent also uses ditches for sewage treatment, its The structural design of trenches to treat sewage is completely different. The farmland sewage treatment method adopts the usual wetland structure, and the layer structure from top to bottom is soil layer, filter material layer, gravel cushion, and anti-seepage layer. Commonly used herbaceous plants such as Li's grass and reed are planted on the soil layer. This structure design, which adopts the separation of the soil layer and the filter material layer and planting herbs, has the problems mentioned above. Therefore, even if it is only applied to domestic sewage treatment, it is still insufficient. It is more difficult to apply to rainwater treatment at the same time, and it is not suitable for rural areas. Reconstruction of the existing open-channel sewage ditches with a large number of rain and sewage combined systems. In addition, the patent lacks the concept of grading purification, does not consider the demand for nitrogen and phosphorus nutrients of crops during farmland irrigation and reuse, and the removal performance of the filter material is unclear.

The fourth patent is the Chinese invention patent application number 200920229997.2, application date 2009.11.18, publication number CN201554013U, and the patent name is "an ecological pollution reduction type drainage ditch". A hole in which submerged plants are planted. Its main shortcomings are: 1) The sewage accumulates on the surface of the facility, and the odor is easily emitted into the surrounding air, making the environment unfriendly. 2) During heavy rain, the dense submerged plants in the ditch hinder the drainage of rainwater, which is easy to cause waterlogging. 3) The need for farmland irrigation and reuse is not considered, and the concept of using different types of filter media for graded purification is lacking. When the effluent quality is the standard for farmland irrigation, nitrogen and phosphorus are not pollutants but nutrients of crops, and should be avoided as much as possible during purification.

Utility model content

The purpose of this utility model is to overcome the deficiencies existing in the prior art, and to provide a graded ecological treatment system for treating rural domestic sewage and rainwater, so that it can purify rural domestic sewage while discharging sewage on weekdays. Filter material, so that the sewage discharged from the grading ecological treatment system can meet the first-level farmland irrigation standard and the second-level first-level A discharge standard. At the same time, in rainy days, the most polluted initial rainwater runoff can be stored in a series of reservoirs along the new ecological ditches or in the reservoirs of ecological gardens, and then discharged after infiltration and purification. This can not only greatly reduce the initial stormwater runoff pollution, but also reduce stormwater runoff by storing stormwater runoff through a series of cisterns, reducing flood pressure on receiving water bodies such as rivers during storms. In addition, this new type of LID ecological ditches/gardens also have ecological landscape features. It is a new type of LID ecological treatment system that combines ecological landscape functions with the functions of "infiltration, storage, stagnation, purification and drainage". The coordination and unity of water control and ecological environment construction.

In order to achieve the above object, the technical solution of the present utility model is:

A graded ecological treatment system for treating rural domestic sewage and rainwater. When the effluent quality is required to be the standard for farmland irrigation, the ecological treatment system is composed of a first-level LID new ecological ditch garden and a reservoir, which is called a first-level ecological treatment system. . The effluent of the primary ecological treatment system flows into the reservoir, and the water in the reservoir is reused for farmland through the farmland irrigation system. When the effluent quality is required to be the first-level A discharge standard, on the basis of the first-level ecological treatment system, a second-level LID new ecological ditches/gardens are further added to form a second-level ecological treatment system. The effluent of the first-level LID new ecological ditches/gardens is first reused for farmland through the farmland irrigation system, and the remaining water from the irrigation water enters the second-level LID new ecological ditches/gardens through the overflow port of the reservoir for further infiltration and purification. After reaching the first-level A discharge standard, the effluent is directly discharged into the receiving water body, or the groundwater is infiltrated through the diffusion and infiltration pipe network laid under the surface to form a good hydrological cycle.

The vertical structure of the first-level LID new ecological ditches/gardens is composed of an aquifer layer, a volcanic rock filter material layer planted with moisture-resistant and dirt-resistant woody plants, and an anti-seepage layer from top to bottom. The thickness of the filter material layer is preferably 30-50cm, and the specific layer thickness can be adjusted according to the water quality of the influent and the construction conditions on site.

The vertical structure of the second-level LID new ecological ditches/gardens is composed of an aquifer layer, a composite filter layer for planting moisture-resistant and dirt-resistant woody plants, and an impermeable layer from top to bottom. Among them, the composite filter material layer is a composite filter material layer composed of volcanic rock, zeolite, and sponge iron in a volume ratio of 3:2:1. The volume ratio can also be appropriately adjusted according to the influent water quality on site. When the content of COD and BOD ₅ in the influent water quality is high, the proportion of volcanic rock can be increased. When the content of ammonia nitrogen and total nitrogen is high, the proportion of activated zeolite can be appropriately increased. When the content of total phosphorus is high, the proportion of activated zeolite can be appropriately adjusted. High percentage of sponge iron. The total layer thickness of the composite filter material layer is preferably 30-60 cm.

For the second-level LID new ecological ditches/gardens, in order to save the cost of filter media, artificially improved soil can be used to partially replace the upper, middle or lower layers of the composite filter media layer. The artificially improved soil is evenly mixed with soil and sand in a mass ratio of 50-70%: 30-50%. At this time, the total layer thickness of the composite filter material layer and the artificially improved soil layer is preferably 30-60 cm.

The first and second-level LID new ecological ditches/gardens, when the designed flood discharge flow is large, so that the filter material will not be lost due to rain erosion in rainy days, an additional layer of covering layer can be added on the filter material layer (the material is cobblestone or pebbles or gravel), add a drainage layer under the filter material layer.

For the first- and second-level LID new ecological ditches/gardens, when the designed sewage hydraulic load is large, in order to keep the ditches dry on weekdays, a perforated sewage water distribution pipe can be arranged in the outermost packing layer, and in the bottommost packing layer Perforated water collection pipes are arranged at the bottom. The filler layer here includes a cover layer, a filter material layer, an artificial improvement layer, and a drainage layer. When there is no covering layer in the ecological ditches/gardens, the outermost packing layer is the filter material layer, and so on.

The vertical structure of the first- and second-level LID new ecological ditches/gardens has slopes along the way, that is, the bottom elevation of the ditches/gardens at the water inlet is higher than the bottom height of the water outlet. Several large stones can be placed on the surface of the uppermost packing layer of the ecological ditch at intervals along the cross-sectional direction, and several dry stone retaining weirs can be formed along the way to store the early rainwater runoff in rainy days for infiltration and purification (non- necessary), the elevation of the top of the retaining weir is lower than the elevation of the two banks of the ditch, so that the excess rainwater can be discharged from the top of the weir to the downstream of the ditch.

The first and second-level LID new-type sewage ditches are planted with moisture-resistant and pollution-resistant woody plants in the ditches. In the southern region, camphor trees, loquat trees, frangipani, oleander, sunflower and hibiscus can be planted.

After adopting the above-mentioned scheme, the utility model has the following advantages compared with the prior art:

1. The LID novel ecological treatment system described in the present utility model has multiple functions such as "infiltration, storage, stagnation, netting, and rowing", and compared with the prior art, this ecological ditches have the following advantages:

(1) Adopting graded purification, the nitrogen and phosphorus nutrients in the sewage are retained as much as possible in the primary purification and reused for farmland irrigation, and the remaining residual water is reused and further purified to grade A through the secondary purification. This graded treatment The process makes the sewage be recycled and protects the water environment.

(2) The use of woody plants instead of herbs makes the new LID ecological treatment system suitable for extensive rural management. The planted waterlogging-tolerant and pollution-resistant woody plants can form an ecological landscape belt, which echoes the needs of the construction of beautiful rural ecological landscapes. In addition, by planting woody plants in the filter material layer of the present invention, the developed root system microorganisms can strengthen the decomposition of organic pollutants, and in addition, the developed root system can also absorb and transform more nitrogen and phosphorus nutrients in the layer. material, turning pollutants into plant nutrition sources, forming a good ecological cycle, ensuring the sustainable purification function of the filter material, and eliminating the need to replace the filter material from time to time. At present, the vertical structure of subsurface wetlands and various soil infiltration systems is usually the planting soil layer, the sewage water distribution layer, the filter material layer, and the drainage layer from top to bottom. Because the plants are planted in the uppermost soil layer, and they are all herbs, the roots of herbs are shallow and cannot pass through the water distribution layer into the filter layer, so that the nutrients trapped in the filter layer cannot be absorbed. After transformation, root microorganisms cannot enter the filter layer to assist in the decomposition of organic pollutants. As a result, the filter material of the filter material layer is easy to lose the purification effect due to the saturation of adsorption after many years of operation, and the filter material has to be replaced.

(3) It can not only purify domestic sewage and initial rainwater runoff, reduce pollutants to protect the water environment of the receiving water body, but also reduce part of the stormwater runoff by storing the initial rainwater runoff, thereby reducing the flooding of rivers during heavy rain. pressure, to achieve the coordination and unity of pollution control and water control.

(4) When the amount of sewage discharge is large, since the sewage is rapidly infiltrated through the water distribution pipes buried under the surface of the covering layer, there will be no sewage accumulation on the surface of the ditch, and the surface of the ditch can be kept dry and beautiful on weekdays.

(5) The water retaining weir of the present utility model is formed by simply placing several large stones on the surface of the ditch covering layer to form a rough and primitive dry stone retaining weir with gaps, which is not only simple in construction, but also has better ecological landscape. .

Description of drawings

1 is a schematic cross-sectional view of the LID novel ecological ditch provided by Embodiment 1 of the present utility model;

Fig. 2 is the longitudinal sectional schematic diagram of the LID novel ecological ditch provided by the utility model embodiment 1;

3 is a schematic cross-sectional view of the LID novel ecological ditch provided by Embodiment 2 of the present utility model;

FIG. 4 is a schematic longitudinal cross-sectional view of the new LID ecological ditch provided by Embodiment 2 of the present invention.

Detailed ways

The present utility model will be described in further detail below in conjunction with the accompanying drawings and specific embodiments. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention may be embodied in various forms and should not be limited by the embodiments set forth herein. If no specific technology or condition is indicated in the examples, the technology or condition described in the literature in the field or the product specification is used.

Example 1

This embodiment is to build a first-level ecological treatment system. The influent water quality of this embodiment: COD: 200mg/L, BOD ₅ : 75.1mg/L, total phosphorus: 1.77mg/L, total nitrogen: 10.9mg/L, ammonia nitrogen: 5.17mg/L, pH: 7.51; effluent The water quality design standard is to meet the farmland irrigation standard. The actual effluent water quality test results are: COD: 54.56, BOD ₅ : 7.90mg/L, total phosphorus: 1.65mg/L, total nitrogen: 8.21mg/L, ammonia nitrogen: 4.93mg/L , pH: 7.78; the effluent water quality meets the farmland irrigation standards required by the design, including the farmland irrigation standards for dry farming, water farming, and vegetables.

The first-level ecosystem is composed of first-level LID new ecological ditches and reservoirs. The first-level LID new ecological ditches are shown in Figures 1-2.

The first-level LID new ecological ditch includes a ditch body 1, a water retaining weir 2, an overflow 3, a reservoir 4, a covering layer 5, a filter material layer 6, a drainage layer 7, a perforated water collection pipe 8, and an anti-seepage surface 9 , Perforated sewage water distribution pipe 10, moisture-resistant and dirt-resistant woody plants 11, and ecological slope protection 12.

The ditch body 1 refers to the excavated concave body with a rectangular bottom and a trapezoid on the top (the concave body with the cross-sectional shape enclosed by the short diagonal line in Figure 1), and the ditch body is covered by aquifers, layer, filter material layer and drainage layer. The aquifer (pool) 4 is located between the upstream and downstream two retaining weirs, the retaining weir 2 is located above the covering layer 5, and the inner sides of the two banks above the covering layer 5 are ecological slope protection 12. The perforated sewage water distribution pipe 10 is located in the covering layer 5 , and the perforated water collecting pipe 8 is located at the bottom of the drainage layer 7 . In order to prevent the fine particles in the filter material from falling to the bottom of the drainage layer 7, the particles of the filler of the drainage layer 7 gradually change from fine to coarse from top to bottom.

The longitudinal structure of the ditch body 1 is the same as that of a common sewage ditch, and there is a slope along the route (the left side is slightly higher than the right side in Figure 2); A series of continuously distributed reservoirs 4 are formed along the ditch to store the initial rainwater runoff with the largest pollution load for infiltration, and the excess rainwater runoff is drained through the overflow port of the retaining weir 2 and the top of the weir.

On a sunny day on weekdays, the rural domestic sewage leaks to the filter material layer 6 through the perforated sewage water distribution pipe 10 buried in the cover layer 5, and is purified by this layer of filter material adsorption, microbial decomposition, and plant root absorption, and then penetrates into the drainage layer. , and then discharged through the perforated water collecting pipe 8 buried in the layer. The effluent enters the reservoir and is irrigated and reused through the farmland irrigation system.

In rainy days, when the rainwater runoff flows into the ecological ditch, a part of the rainwater runoff will infiltrate into the drainage layer 7 through the covering layer 5, the filter material layer 6, and finally be discharged through the perforated water collection pipe 8 buried at the bottom of the drainage layer; The infiltrated rainwater runoff will be temporarily stored in the reservoir 4 , and then slowly percolated and discharged through the bottom perforated water collection pipe 8 . When the rainwater runoff fills the uppermost reservoir 4 of the ditch, the excess rainwater runoff will flow into the next reservoir through the overflow port 3 or the top of the weir 2 until all the reservoirs along the way are full. At this time, when the rainwater runoff flows into the sewage ditch, it will be directly discharged through the overflow port and the top of each water storage weir. Since the initial rainwater runoff with the largest pollution load can be stored in the reservoir 4 of the sewage ditch, and slowly filtered and purified, the sewage ditch can not only reduce the rainstorm runoff, but also reduce the amount of water that receives water such as rivers. Flood pressure, and can greatly reduce rainwater non-point source pollution.

The construction process of the first-level LID novel ecological system described in the utility model is as follows: firstly, constructing a first-level LID novel ecological ditch; secondly, constructing a reservoir, and the reservoir is provided with a water intake near the bottom of the pool, and the water intake is provided with an on-off valve or sluice gate, in addition, there is an overflow port on the top of the reservoir. The water from the ecological ditches flows into the reservoir, and the water in the reservoir flows into the farmland irrigation system through the water intake of the reservoir. Among them, the construction process of the first-level LID new ecological ditch is as follows:

Step 1: First, further dig the existing sewage ditch in the countryside to form a ditch body 1 with a rectangular and trapezoidal cross-section enclosed by a short diagonal line in Figure 1.

The second step: lay an impermeable geotextile on the bottom bed of the trench body after the excavation is completed, as the anti-seepage surface 9, and then lay two perforated water collecting pipes 8 with a pipe diameter of 8cm on the geotextile;

Step 3: Fill in the lower, middle and upper layers of the drainage layer layer by layer from bottom to top. First, fill in large stones with a particle size of 8-16mm, and fill in with a thickness of 10cm; then, fill in 4-8cm stones with a thickness of 10cm; finally, fill in small stones with a size of 2-5mm, with a thickness of 10cm;

Step 3: Fill in 1-3mm volcanic rock with a filling thickness of 40cm;

The fourth step: planting pollution-resistant and waterlogging-resistant woody plants oleander and loquat in the filter material layer 6;

Step 5: Fill the filter material layer 6 with gravel with a thickness of 8 cm and a particle size of 16-32 mm; then lay a perforated sewage water distribution pipe 10 with a pipe diameter of 4 cm. 16-32mm of gravel until a covering layer 5 with a total thickness of 20cm is formed;

Step 7: Place a number of large stones on the cover layer 5 at a longitudinal distance of 25m. The large stones and the large stones are closely adjacent to each other along the cross section of the ditch to form a low dry stone retaining weir 2 in the middle. The height of the block stone is lower than other blocks, forming the overflow of the retaining weir 2, and the elevation of the weir top is 15cm lower than the top of the bank on both sides of the ditch. In case of heavy rain, a large amount of rainwater runoff will flow into this new type of ditch, and the rainwater that is too late to infiltrate will be stored in the reservoir 4 formed by the upstream and downstream two retaining weirs. Of course, a small part of the rainwater will be blocked by dry stone. The gap of the weir 2 and the overflow port of the retaining weir flow downstream. In addition, when the rainwater runoff is filled with the reservoir 4, it will flow to the downstream of the ditch through the overflow port of the retaining weir or the top of the weir.

Step 8: Plant turf on both sides of the slope above the ditch cover layer 5 to form an ecological slope 12.

Example 2

This embodiment is a new type of secondary LID ecosystem. The influent water quality of the system is COD: 200mg/L, BOD ₅ : 75.1mg/L, total phosphorus: 1.77mg/L, total nitrogen: 10.9mg/L, ammonia nitrogen: 5.17mg /L, pH: 7.51; the design standard of effluent water quality is Grade A, the actual effluent water quality test results are: COD: 16mg/L, BOD ₅ : 3.76mg/L, total phosphorus: 0.16, total nitrogen: 1.38mg/L, Ammonia nitrogen: 0.82mg/L, pH: 7.98, the effluent quality meets the design requirements of Class A.

The second-level LID novel ecosystem is composed of the first-level LID novel ecosystem and the second-level LID novel ecological ditches of the aforementioned Example 1. The second-level LID new ecological ditches are shown in Figures 3-4.

The second-level LID new ecological ditch includes a ditch body 1, a water retaining weir 2, an overflow 3, a reservoir 4, a covering layer 5, a filter material layer 6, an artificially improved soil layer 7, a drainage layer 8, and a perforated water collection pipe. 9. Anti-seepage surface 10, perforated sewage water distribution pipe 11, moisture-resistant and dirt-resistant woody plants 12, and ecological slope protection 13.

The ditch body 1 refers to the trapezoidal concave body that is excavated (the concave body with the cross-sectional shape enclosed by the short diagonal line in Figure 1). It is composed of artificially improved soil layer and drainage layer. The aquifer (pool) 4 is located between the upstream and downstream two retaining weirs, the retaining weir 2 is located above the covering layer 5 , and the inner sides of the two banks above the covering layer 5 are ecological slope protection 13 . The perforated sewage water distribution pipe 10 is located in the covering layer 5 , and the perforated water collecting pipe 9 is located at the bottom of the drainage layer 8 . In order to prevent the fine particles in the filter material from falling to the bottom of the drainage layer 8, the filler of the drainage layer 8 is divided into three layers, and the particles gradually become coarser from top to bottom.

The construction process of the secondary LID new ecological ditches is as follows:

Step 1: First, further dig the existing sewage ditches in rural areas to form a trapezoidal cross-sectional ditch body 1 enclosed by the short slashes in Figure 3.

The second step: laying mortar and masonry on the bottom bed surface and slope surface of the trench body after excavation is completed to form an anti-seepage surface 10, and then laying two perforated water collecting pipes 9 with a pipe diameter of 8 cm;

Step 3: Fill the lower, middle and upper layers of the drainage layer 8 layer by layer from bottom to top. First, fill in large stones with a particle size of 4-8mm, and fill in with a thickness of 10cm; then, fill in 2-5cm stones with a thickness of 10cm; finally, fill in small stones with a size of 1-3mm, with a thickness of 10cm;

Step 4: Fill in 30cm of artificially improved soil. The artificially improved soil is evenly mixed with red loam and sand in a mass ratio of 1:1.

Step 5: Fill the composite filter material layer with a filling thickness of 30cm; the composite filter material layer is made of 1-3mm volcanic rock, 1-2mm zeolite, and 1-3mm sponge iron according to the volume ratio of 3:2:1. The formed composite filter material layer, or from bottom to top, is filled by layers of sponge iron layer, activated zeolite layer and volcanic rock layer to form a composite filter material layer with three layers.

The sixth step: planting pollution-resistant and waterlogging-resistant woody plants oleander and loquat in the filter material layer 6;

Step 7: Fill the top of the filter material layer 6 with gravel with a thickness of 8 cm and a particle size of 8-16 mm; then lay a perforated sewage water distribution pipe 11 with a pipe diameter of 4 cm. 8-16mm of gravel until a covering layer 5 with a total thickness of 20cm is formed;

Step 8: Place several large stones on the cover layer 5 at a longitudinal distance of 25m. The large stones and the large stones are closely adjacent to each other along the cross section of the ditch to form a low dry stone retaining weir 2, in the middle. The height of the block stone is lower than other blocks, forming the overflow of the retaining weir 2, and the elevation of the weir top is 15cm lower than the top of the bank on both sides of the ditch.

The ninth step: plant turf on the slopes on both sides above the ditch cover layer 5 to form an ecological slope 13 .

The preferred embodiments of the present utility model have been described in detail above, but the present utility model is not limited to the specific details of the above-mentioned embodiments. Within the scope of the technical concept of the present utility model, various simple modifications can be made to the technical solutions of the present utility model. . For example, the cover layer and drainage layer can be omitted in the first and second-level LID new ecological ditches under the condition that the designed flood discharge is not large. The artificial improvement layer in the second-level LID new ecological ditches can be set or not. The actual situation may be set or not, and these simple modifications all belong to the protection scope of the present invention.

In addition, it should be noted that, the specific technical features described in the above-mentioned specific embodiments can be combined in any suitable manner under the circumstance that there is no contradiction. In order to avoid unnecessary repetitions, various possible combinations are not described in the present invention.

In addition, the various embodiments of the present invention can also be arbitrarily combined, as long as they do not violate the idea of the present invention, they should also be regarded as the contents disclosed in the present invention.

Claims (6)

1. The utility model provides a handle rural domestic sewage and dirty hierarchical ecological treatment system of rain, its characterized in that: when the water quality of the effluent is required to be a farmland irrigation standard, the ecological treatment system consists of a first-level LID novel ecological ditch/garden and a reservoir and is called a first-level ecological treatment system; wherein, the vertical structure of the first-level LID novel ecological ditch/garden consists of a water storage layer, a volcanic rock filter material layer planted with moisture-proof and stain-resistant woody plants and an impermeable layer from top to bottom; the thickness of the filter material layer is 30-60 cm; the reservoir is provided with a water intake and an overflow port, and the farmland irrigation system is connected with the water intake of the reservoir; the longitudinal structure of the novel ecological ditch/garden of the first-level LID is that a slope exists along the journey, namely the bottom elevation of the side of the ecological ditch/garden where water enters is higher than that of the side where water exits.

2. The staged ecological treatment system for treating rural domestic sewage and rain sewage according to claim 1, wherein: when the effluent quality requirement is the first-level A discharge standard, the ecological treatment system also comprises a second-level LID novel ecological ditch/garden land on the basis of the first-level ecological treatment system to form a second-level ecological treatment system; the effluent of the first-level LID novel ditch/garden land enters a reservoir and then is reused for farmland irrigation through a farmland irrigation system, the residual irrigation water enters a second-level LID novel ecological ditch/garden land through an overflow port of the reservoir and is further percolated and purified, and the effluent quality reaches a first-level A discharge standard; the vertical structure of the novel ecological ditch/garden with the secondary LID consists of a water storage layer, a composite filter material layer for planting moisture-proof and stain-resistant woody plants and an impermeable layer from top to bottom; the thickness of the composite filter material layer is 30-60 cm; the longitudinal structure of the novel ecological ditch/garden with the secondary LID is that a slope exists along the journey, namely the bottom elevation of the side of the ecological ditch/garden where water enters is higher than that of the side where water exits.

3. The staged ecological treatment system for treating rural domestic sewage and rain sewage according to claim 2, wherein: the composite filter material layer comprises part of artificially improved soil.

4. The staged ecological treatment system for treating rural domestic sewage and rain sewage according to any one of claims 1 to 3, wherein: a covering layer is additionally arranged on the filter material layer, and the covering layer is made of rock blocks, cobblestones or gravels; in addition, a drainage layer is additionally arranged below the filter material layer in order to enhance the drainage function of the ecological treatment system.

5. The staged ecological treatment system for treating rural domestic sewage and rain sewage according to claim 1 or 2, wherein: the graded ecological treatment system for treating rural domestic sewage and rain sewage is characterized in that a plurality of large stones are placed on the top layer of the filler of a ditch at intervals along the cross section direction, a plurality of dry stone retaining weirs are formed along the way so as to be convenient for rainwater runoff at the initial storage stage in rainy days to be percolated and purified, the dry stone retaining weir is unnecessary, and the elevation of the top of the retaining weir is lower than that of two banks of the ditch so as to drain redundant rainwater to the downstream of the ditch from the weir top.

6. The staged ecological treatment system for treating rural domestic sewage and rain sewage according to claim 1 or 2, wherein: moisture-resistant and stain-resistant woody plants planted in ecological ditches/gardens in southern areas employ camphor trees, loquat trees, frangipani, oleander, sunflower seeds or hibiscus.

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