A rural domestic sewage treatment system and method for small watersheds

Abstract

The present invention relates to the technical field of domestic sewage treatment, and specifically discloses a small watershed rural domestic sewage treatment system and method. The method is to separately collect and treat black water and grey water in the farmer's courtyard, and through ditch transformation, utilization of the ecological treatment module system and the natural ecological system, sewage purification is realized. The system treats rural domestic sewage by combining the grey water treatment device with the ecological treatment module system, can overcome the disadvantages of high infrastructure cost, large floor area, complex management, high operation cost, poor ecology, etc., and obtains the tail water that can be directly utilized, truly realizing sewage purification, recycling, and turning waste into treasure.

Description

Technical Field

[0001] The present invention relates to the technical field of rural domestic sewage treatment, and particularly relates to a small watershed rural domestic sewage treatment system and method. Background Art

[0002] After years of scientific research and practical exploration, significant progress has been made in rural domestic sewage treatment technologies and equipment. There are many types of rural domestic sewage treatment technologies, which can be classified into three categories according to their principles: biological treatment technologies, ecological treatment technologies, and physical and chemical treatment technologies. Among them, biological treatment technologies mainly include activated sludge method, biofilm method, etc.; ecological treatment technologies mainly include land infiltration system, constructed wetland, stabilization pond, etc.; physical and chemical treatment technologies mainly include coagulation, flotation, adsorption, ion exchange, electrodialysis, reverse osmosis, and ultrafiltration. In actual applications, more often it is a combination of multiple processes, such as anaerobic pond + aerobic pond + constructed wetland, anaerobic pond + stabilization pond, etc. Generally speaking, for relatively economically developed areas, the suitability of rural domestic sewage treatment technologies is relatively good; for less economically developed areas, due to factors such as scattered spatial distribution of villages and population, low aggregation degree, large fluctuations in water quality and quantity, and economic underdevelopment, the overall suitability is relatively poor.

[0003] A method for ecological enhanced self-purification of river and ditch sewage invented by Li Jingsheng is to utilize the space of the river (channel), and form a wetland oxidation pond by building several levels of base weirs to purify the sewage. However, with the rapid economic development of our country, the continuous increase in sewage concentration, pollutants, and production volume, and the continuous increase in the number of rural households converting dry toilets to flush toilets, this method is prone to problems such as poor treatment effect and environmental pollution. A method for treating rural domestic sewage invented by Chen Chaomin is to separately treat feces, urine, and the rest of the domestic sewage. The domestic sewage enters the biological pond for biological contact oxidation treatment. This method is more applicable in relatively economically developed rural areas, and is not applicable in other less economically developed rural areas due to problems such as high cost and complex operation and maintenance management.

[0004] Compared with cities, rural areas have strong land absorption capacity and extensive natural ecological systems, which are favorable conditions for ecological treatment of rural domestic sewage. Considering the general situation of weak financial resources, low technical and management capabilities in vast rural areas of our country, it is very necessary to develop a rural domestic sewage treatment method that conforms to the actual situation in rural areas, has low construction cost, good treatment efficiency, low operation cost, and is easy to manage on the basis of scientifically and reasonably utilizing the land absorption capacity in rural areas. Summary of the Invention

[0005] To solve the problems existing in the prior art, the object of the present invention is to provide a small watershed rural domestic sewage treatment system and method. Taking the small watershed as the rural domestic sewage treatment unit, following the basic path of separating black and gray water, transforming ditches, and utilizing tail water, promoting the resource utilization of fecal sewage and the ecological transformation of ponds and ditches, strengthening the connection between tail water and farmland irrigation reuse, ecological restoration, etc., so that rural domestic sewage can be naturally purified, recycled, and turned waste into treasure within the small watershed range.

[0006] To achieve the object of the present invention, the technical solution of the present invention is as follows:

[0007] In the first aspect, the present invention provides a small watershed rural domestic sewage treatment method, and the method includes the following steps:

[0008] (1) Separating black and gray water: Collecting and treating black water and gray water separately in the farmer's courtyard;

[0009] The collected black water is first discharged into the septic tank for harmless treatment. The fecal residue is directly diluted for utilization or produced into organic fertilizer for resource utilization. The fecal liquid in the third compartment of the septic tank is discharged into the ditch outside the courtyard through the farmer's sewage collection pipe, or reused for small gardens, small vegetable gardens, small orchards, etc. in front of and behind the house; The collected gray water is discharged into the ditch after being treated by the gray water treatment device;

[0010] (2) Ditch treatment: Transforming the ditch to make the wastewater discharged into the ditch flow through more than one ecological treatment module for in-depth purification;

[0011] (3) Tail water utilization: Discharging or using the up-to-standard tail water obtained after being treated by the ecological treatment module system for farmland irrigation to realize the resource utilization of tail water.

[0012] Further, in the step of separating black and gray water, the septic tank is any one of rectangular, eye-shaped, product-shaped, can-shaped, T-shaped, circular and other three-compartment septic tanks. The gray water treatment device includes a grid screen and absorbent cotton, and is used to remove large particulate matter and oil substances in the collected gray water.

[0013] In practical applications, the farmer's drainage pipe is connected to the gray water treatment device, and the diameter of the connecting pipe is 100mm - 1000mm, and the pipe material is selected from one of UPVC, PVC, PP winding pipe, and HDPE.

[0014] Furthermore, in the ditch treatment step, the ditches in the village mainly involve building new ditches or repairing damaged ones. At the same time, anti-seepage treatment should be carried out using materials such as concrete, masonry, and membrane materials. The width of the ditches is 0.5m - 2m, and the depth is 0.3m - 1.5m. The ditches outside the village are built, dredged, or expanded based on grassed swales and damaged ditches. The side walls of the ditches can be built with honeycomb cement boards, grass grid bricks, etc. The width of the ditches is 0.5m - 5m, and the depth is 0.5m - 3m.

[0015] The function of the ditches in the village is to receive the sewage from the greywater treatment device and the daily dumped wastewater. The sewage flows from the ditches in the village into the ditches outside the village, and then into rural natural environments such as streams, rivers, farmlands, or infiltrates into the soil, completing the purification and recycling of the sewage.

[0016] Ecological treatment module systems need to be used in the ditches for ecological transformation to reduce water pollutants in the fecal liquid and greywater.

[0017] The size of the ecological treatment module can be adjusted to adapt to the width of the ditch, and the number of modules is determined by factors such as the length of the ditch and the requirements for tail water discharge.

[0018] When the ditch water is finally discharged into surface water function zones II and III of GB 3838, enclosed or semi-enclosed waters, and small micro-waters with unclear environmental functions such as rivers, lakes, reservoirs with small dilution capacities, and ponds near villages (executing the first-class standard), 5 - 35 ecological treatment modules are adopted per kilometer of the ditch.

[0019] When the ditch water is finally discharged into surface water function zones IV and V of GB 3838, wetlands, farmlands, and forestlands (executing the second-class standard), 2 - 20 ecological treatment modules are adopted per kilometer of the ditch.

[0020] In a second aspect, the present invention provides a rural domestic sewage treatment system for small watersheds, including an ecological treatment module. The ecological treatment module includes a bottom plate and a purification component. The bottom plate is arranged in the ditch, and the purification component is arranged on the bottom plate. A first clamping structure and a second clamping structure for clamping cooperation are respectively arranged at the front end and the rear end of the bottom plate, and multiple bottom plates are connected end to end through the first clamping structure and the second clamping structure.

[0021] Optionally, the first clamping structure and the second clamping structure are respectively a clamping groove and a clamping buckle. A screen is arranged at the clamping groove, and the screen is slidably inserted into the clamping groove in the vertical direction. The two bottom plates are seamlessly connected through the clamping groove and the clamping buckle.

[0022] Optionally, it further includes a grey water treatment device, which is provided with a water inlet and a water outlet. The grey water treatment device and the ecological treatment module are communicated through the water outlet. The grey water treatment device includes a filtration chamber and a sedimentation chamber. The filtration chamber and the sedimentation chamber are separated by a first partition board. A first overflow port communicating the filtration chamber and the sedimentation chamber is arranged on the first partition board. The water inlet is communicated with the upper section of the filtration chamber, and the water outlet is communicated with the upper section of the sedimentation chamber. A first oil-absorbing cotton is arranged in the filtration chamber.

[0023] Optionally, a pair of the first oil-absorbing cottons are both inclinedly arranged in the filtration chamber and divide the filtration chamber into three filtration cavities along the water flow direction.

[0024] Optionally, a second partition board is arranged between a pair of the first oil-absorbing cottons. The second partition board separates the two first oil-absorbing cottons, and a second overflow port is opened on the second partition board.

[0025] Optionally, a plurality of the first overflow ports are arranged on the first partition board, and an inspection port is arranged at the top of the grey water treatment device.

[0026] Optionally, a second oil-absorbing cotton is arranged on the side of the first partition board facing the filtration chamber.

[0027] Optionally, the grey water treatment device further includes a grid screen arranged at the water inlet. The grid screen is horizontally arranged above the first oil-absorbing cotton. One side of the grid screen is connected to the inner wall of the filtration chamber, and the end of the grid screen far from the water inlet is connected to the upper end of the first oil-absorbing cotton close to the water inlet. The upper end of the first oil-absorbing cotton close to the water inlet is connected to the top of the filtration chamber through a baffle.

[0028] Optionally, the purification component includes a sedimentation tank, a purification adsorption device and a plant purification tank arranged in sequence along the water flow direction. Three grooves embedded in the bottom of the ditch are arranged on the bottom plate. The sedimentation tank, the purification adsorption device and the plant purification tank are respectively arranged in the three grooves. The upper section of the purification adsorption device extends upward to a height higher than the bottom of the ditch.

[0029] Optionally, the purification adsorption device includes three layers of filling tanks, and three kinds of purification materials are respectively filled in the three layers of filling tanks. The filling materials are selected from one or more of zeolite, ceramsite, quartz sand, vermiculite, steel slag and blast furnace slag. Biological film hanging suspension fillers are arranged in the sedimentation tank, and plant units are arranged in the plant purification tank.

[0030] The plant unit plants plants with good pollutant absorption effect, which are emergent plants, or submerged plants, or a combination of emergent plants and submerged plants, so as to naturally purify the sewage and conserve the plants in the channel, and better cycle and absorb, so as to purify the sewage.

[0031] The specific planting scheme of the plants is as follows:

[0032] For emergent plants, 2 - 10 plants / m 2 , selected from one or more of Thalia dealbata, Acorus calamus, Typha orientalis, Phragmites australis, Alisma plantago-aquatica, Lythrum salicaria, Scirpus validus, Pontederia cordata, Canna indica, Zizania latifolia, Sagittaria trifolia, Cortaderia selloana, Polygonum orientale.

[0033] For submerged plants, 5 - 15 plants / m 2 , selected from one or more of Myriophyllum spicatum, Potamogeton crispus, Vallisneria natans, Hydrilla verticillata, Ceratophyllum demersum, Myriophyllum verticillatum.

[0034] The operations involved in the present invention are all conventional operations in the art without special instructions.

[0035] On the basis of conforming to the common knowledge in the art, the above preferred conditions can be combined with each other to obtain specific implementation manners.

[0036] The beneficial effects of the present invention are as follows:

[0037] The present invention provides a small watershed rural domestic sewage treatment system and method, which is guided by sewage reduction, classified on-site treatment and recycling, overall strengthens the organic connection with farmland irrigation reuse, ecological restoration, landscape greening, etc., innovates the design mode of rural domestic sewage treatment, makes full use of the natural treatment system, realizes the virtuous cycle of agricultural and rural water resources and organic waste, and forms an ecological and resource-based rural domestic sewage treatment technology method.

[0038] The present invention also provides a small watershed rural domestic sewage treatment system, which can assemble a sewage treatment system meeting the actual needs according to rural sewage discharges with different environments, different positions and different specifications, innovates the design mode of rural domestic sewage treatment, and effectively solves the technical problems such as high infrastructure cost, large floor area, high operation cost, complex management and poor ecology existing in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The drawings here are incorporated into the specification and form a part of this specification, showing the embodiments conforming to the present invention, and are used together with the specification to explain the principles of the present invention.

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0041] Figure 1 Structural schematic diagram of the small watershed rural domestic sewage treatment system described in the embodiment of the present invention;

[0042] Figure 2 Structural schematic diagram of the splicing of the screen and the clamping groove described in the embodiment of the present invention;

[0043] Figure 3 Structural schematic diagram of the clamping groove described in the embodiment of the present invention;

[0044] Figure 4 Structural schematic diagram of the clamping buckle described in the embodiment of the present invention;

[0045] Figure 5 Structural schematic diagram of the screen described in the embodiment of the present invention.

[0046] Among them, 1, water inlet; 2, grid screen; 31, first oil-absorbing cotton; 32, second oil-absorbing cotton; 4, inspection port; 5, first overflow port; 6, sedimentation chamber; 7, water outlet; 8, screen; 9, biological film hanging suspension filler; 10, sedimentation tank; 11, purification and adsorption device; 12, plant unit; 13, plant purification tank; 14, ditch; 15, first partition board; 16, bottom plate; 161, clamping groove; 162, clamping buckle; 17, baffle; 18, second partition board; 19, second overflow port. Specific embodiments

[0047] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the following will further describe the solutions of the present invention. It should be noted that, without conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0048] In the following description, many specific details are set forth in order to fully understand the present invention, but the present invention can also be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only a part of the embodiments of the present invention, rather than all the embodiments.

[0049] The following will specifically describe the preferred embodiments of the present invention in conjunction with the embodiments. It should be understood that the following embodiments are given only for the purpose of illustration, and are not used to limit the scope of the present invention. Those skilled in the art can make various modifications and substitutions to the present invention without departing from the purpose and spirit of the present invention.

[0050] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods.

[0051] Unless otherwise specified, the materials and the like used in the following examples are all commercially available.

[0052] Example 1

[0053] Refer to Figure 1 As shown, a small watershed rural domestic sewage treatment system provided in this example includes an ecological treatment module. The ecological treatment module includes a bottom plate 16 and a purification component. The bottom plate 16 is arranged in a ditch 14, and the purification component is arranged on the bottom plate 16. The bottom plate 16 is made of PVC material. A first clamping structure and a second clamping structure for clamping cooperation are respectively arranged at the front end and the rear end of the bottom plate 16. A plurality of bottom plates 16 are connected end to end through the first clamping structure and the second clamping structure. According to the standards and regions where the ditch water in the ditch 14 finally drains, the number of ecological treatment modules used per kilometer is determined. When the ditch water finally drains into surface water class Ⅳ and Ⅴ functional waters, wetlands, farmlands, and forestlands (implementing class Ⅱ standards) in GB 3838, 2 - 20 ecological treatment modules are adopted per kilometer of the ditch 14. When the ditch water finally drains into surface water class Ⅱ and Ⅲ functional waters, enclosed and semi - enclosed waters, and small and micro water bodies with unclear environmental functions such as rivers, lakes, reservoirs with small dilution capacities and ponds near villages (implementing class Ⅰ standards) in GB 3838, 5 - 35 ecological treatment modules are adopted per kilometer of the ditch 14. This system can assemble a sewage treatment system that meets the actual needs according to different environments, different locations, and different specifications of rural sewage emissions, innovate the design mode of rural domestic sewage treatment, make full use of the natural treatment system, realize the virtuous cycle of agricultural and rural water resources and organic waste, form an ecological and resource - based rural domestic sewage treatment technology, and effectively solve the technical problems such as high infrastructure costs, large floor area, high operating costs, complex management, and poor ecology existing in the prior art.

[0054] Refer to Figures 2 to 5As shown, more preferably, the first clamping structure and the second clamping structure are respectively a clamping groove 161 and a clamping buckle 162. A screen 8 is provided at the clamping groove 161. The screen 8 is slidably inserted into the clamping groove 161 in the vertical direction. The two bottom plates 16 are seamlessly connected through the clamping groove 161 and the clamping buckle 162. It should be noted that the clamping groove 161 and the clamping buckle 162 can be interchanged as long as multiple ecological treatment modules can be assembled and fixed one by one according to requirements. That is to say, the screen 8 can not only be inserted into the clamping groove 161, but also can be inserted into the clamping buckle 162 when the clamping buckle 162 is located upstream of the water flow in the first ecological treatment module. At the same time, the clamping groove 161 and the clamping buckle 162 are not limited to clamping connections and can also be other connection structures that are convenient for connection and disconnection. The height of the screen 8 is 1 / 10 - 1 / 3 of the depth of the ditch 14. Only one screen 8 needs to be provided at the upstream end of the bottom plate 16 in the biological treatment module at the most upstream. The setting of the screen 8 can effectively filter out most of the large-volume wastes upstream of all ecological treatment modules and prevent them from affecting the filtering work of the ecological treatment modules.

[0055] Continue to refer to Figure 1 As shown, in specific implementation, it further includes a grey water treatment device. The grey water treatment device is provided with a water inlet 1 and a water outlet 7. The grey water treatment device and the ecological treatment module are communicated through the water outlet 7. The grey water treatment device includes a filtration chamber and a sedimentation chamber 6. The filtration chamber and the sedimentation chamber 6 are separated by a first partition plate 15. A first overflow port 5 communicating the filtration chamber and the sedimentation chamber 6 is provided on the first partition plate 15. The water inlet 1 is communicated with the upper section of the filtration chamber, and the water outlet 7 is communicated with the upper section of the sedimentation chamber 6. A first oil-absorbing cotton 31 is arranged in the filtration chamber. The setting of the grey water treatment device can effectively remove large particulate matters and oil substances in the grey water.

[0056] Among them, a pair of first oil-absorbing cotton 31 is inclined in the filtration chamber and divides the filtration chamber into three filtration cavities along the water flow direction. The first oil-absorbing cotton 31 is arranged in this way to achieve higher-efficiency filtration and oil absorption work at extremely low cost, improve the filtration efficiency, and also reduce the cost. It should be noted that a second partition plate 18 is arranged between the pair of first oil-absorbing cotton 31 to separate the two first oil-absorbing cotton 31. A second overflow port 19 is opened on the second partition plate 18 to further improve the efficiency of the filtration work.

[0057] At the same time, a plurality of first overflow ports 5 are provided on the first partition plate 15. An inspection port 4 is provided at the top of the grey water treatment device. Opening the inspection port 4 can perform floating oil cleaning or inspection and replacement of the grid screen 2, the first oil-absorbing cotton 31, and the second oil-absorbing cotton 32.

[0058] It should be noted that a second oil-absorbing cotton 32 is arranged on the side of the first partition plate 15 facing the filtration chamber.

[0059] More preferably, the grey water treatment device further includes a grid screen 2 provided at the water inlet 1.

[0060] Among them, the grid screen 2 is horizontally arranged above the first oil-absorbing cotton 31. One side of the grid screen 2 is connected to the inner wall of the filtration chamber. The end of the grid screen 2 far from the water inlet 1 is connected to the upper end of the first oil-absorbing cotton 31 close to the water inlet 1. The upper end of the first oil-absorbing cotton 31 close to the water inlet 1 is connected to the top of the filtration chamber through a baffle 17.

[0061] In this embodiment, more preferably, the purification component includes a sedimentation tank 10, a purification adsorption device 11, and a plant purification tank 13 arranged in sequence along the water flow direction. There are three grooves on the bottom plate 16 that are embedded in the bottom of the trench 14. The sedimentation tank 10, the purification adsorption device 11, and the plant purification tank 13 are respectively arranged in the three grooves. The upper section of the purification adsorption device 11 extends upward to a height higher than the bottom of the trench 14. Among them, the length ratios of the sedimentation tank 10, the purification adsorption device 11, and the plant purification tank 13 are 1:2 - 4:1 respectively. The depth of the sedimentation tank 10 is 0.2m - 1m. The height of the screen 8 and the purification adsorption device 11 is 1 / 15 - 1 / 3 of the depth of the trench 14. The depth of the plant purification tank 13 is 0.2m - 1m. The screen 8, the sedimentation tank 10, the purification adsorption device 11, and the plant purification tank 13 have the same width, which is 40% - 100% of the trench 14.

[0062] Among them, both the sedimentation tank 10 and the plant purification tank 13 are arranged in a form that is embedded in the bottom of the trench 14. When the water flows through, on the one hand, it can be fixed and not washed away by the water flow. On the other hand, the height difference can increase the oxygen content in the water and provide more nutrients for the plants.

[0063] It should be noted that the purification adsorption device 11 includes three layers of filling tanks, and the three layers of filling tanks are respectively filled with three kinds of purification materials. The filling materials are selected from one or more of zeolite, ceramsite, quartz sand, vermiculite, steel slag, and blast furnace slag. There is a biological film hanging suspended filler 9 in the sedimentation tank 10, which helps the attachment and deposition of microorganisms. There is a plant unit 12 in the plant purification tank 13. The plant unit 12 plants plants with good pollutant absorption effects, which are emergent plants and / or submerged plants, so that the sewage is naturally purified and the plants in the canal are conserved, and better cyclic absorption is achieved to purify the sewage.

[0064] Among them:

[0065] Emergent plants, 2 - 10 plants / m 2 , selected from one or several of Thalia dealbata, Acorus calamus, Typha orientalis, Phragmites australis, Alisma plantago-aquatica, Lythrum salicaria, Scirpus validus, Pontederia cordata, Canna indica, Zizania latifolia, Sagittaria trifolia, Cortaderia selloana, Polygonum orientale;

[0066] Submerged plants, 5 - 15 plants / m 2, selected from one or more of the group consisting of Polygonum multiflorum, Water Chestnut, Vallisneria sinensis, Hydrilla verticillata, Duckweed, and Foxtail algae.

[0067] Among them, the ditches 14 are mainly new ditches 14 and repaired damaged ditches 14 in the village. At the same time, concrete, stone masonry, membrane materials and other materials are needed for anti-seepage treatment. The width of the ditch 14 is 0.5m-2m and the depth is 0.3m-1.5m. The ditches 14 outside the village are built, dredged or expanded based on grass-planted ditches and damaged ditches 14. The side walls of the ditches 14 can be built with honeycomb cement boards, grass grid bricks, etc. The width of the ditches 14 is 0.5m-5m and the depth is 0.5m-3m.

[0068] The function of the ditch 14 in the village is to receive sewage from the gray water treatment device and daily dumping of wastewater. The sewage flows from the ditch 14 in the village to the ditch 14 outside the village, and then flows into streams, rivers, farmland or seeps into the soil and other rural natural environments, completing the purification and recycling of sewage.

[0069] The ditch 14 needs to be transformed into an ecological system using an ecological treatment module system to reduce pollutants in rural domestic sewage.

[0070] Example 2

[0071] This embodiment is used to illustrate the application of the small watershed rural domestic sewage treatment system of the present invention to Village A.

[0072] There are three scattered farmer households in Village A, with 3, 6, and 7 households respectively, 1-3 people in each household, and the houses are bungalows built many years ago. Each household is equipped with a dry toilet, and the water supply is tap water. Each household has a washing machine, and there are vegetable fields, farmland and wasteland around the house. First, the manure obtained from the dry toilet is applied back to the vegetable fields and farmland; secondly, the original gray water pipeline of each farmer is integrated and connected to the gray water treatment device. The diameter of the connecting pipe is 400mm, and the pipe material is UPVC. The treated gray water outlet is connected to the nearest branch canal, and the volume of the gray water treatment device is 0.5 cubic meters.

[0073] The terrain is relatively flat, and the original channel in the village was opened and repaired. The ditch is 2km long, 0.5m wide and 0.5m high. Stone masonry and membrane materials are used for anti-seepage treatment, and 4 ecological treatment modules are placed. The ditch outside the village is a natural grass-planted ditch. After repair, it is 1m wide, 0.8m high and 1km long. Two ecological treatment modules are placed. After passing through the ditch outside the village, the sewage flows directly into the natural forest. The ditch sidewalls are made of honeycomb cement boards.

[0074] The ecological treatment module is 0.5m wide and 1.5m long. The movable screen is 0.15m high. The sedimentation device is 0.2m long and 0.3m deep. The purification adsorption device is 0.6m long and 0.15m high. The plant purification tank is 0.2m long and 0.3m deep.

[0075] The plant unit plants submerged plants Myriophyllum spicatum and Hydrilla verticillata, and the planting density is 10 plants / m 2 .

[0076] The three-layer filling tanks of the purification and adsorption device are filled with zeolite, ceramsite and steel slag from top to bottom respectively.

[0077] After determining that it has been running for 15 days, water samples are taken and tested from water bodies at different locations (such as the outlet of the greywater treatment device, the inlet of the ditch outside the village, and the downstream of the ditch outside the village). The test results are shown in Table 1 below.

[0078] Table 1 Water quality indicators after treatment by the rural domestic sewage treatment system and method in small watersheds

[0079] Pollutant type Outlet grey water Inlet of the ditch outside the village Downstream of the ditch outside the village COD (mg / l) 80 49 27 Ammonia nitrogen (mg / l) 5.3 2.1 1.4 Total phosphorus (mg / l) 2.7 0.8 0.2

[0080] It can be seen from the greywater treatment indicators shown in Table 1 that a rural domestic sewage treatment system and method in small watersheds provided by the present invention can significantly reduce the sewage concentration, realize the virtuous cycle of water resources and organic waste in rural areas, have low operating costs and good ecological properties.

[0081] Example 3

[0082] This example is used to illustrate the application of the rural domestic sewage treatment system described in the present invention to Village L.

[0083] There are four scattered households A, B, C, and D in Village L, with 24, 15, 19, and 36 households respectively. Each household has 2 - 5 people. Their residences are newly built bungalows, each equipped with a water closet. The water supply form is tap water. Each household has a washing machine and a shower. There are vegetable plots, farmlands and wastelands around the houses. Each household's water closet is equipped with a pipe network for blackwater collection. There are 4 septic tanks, all of which are rectangular three-compartment septic tanks. After the blackwater is first discharged into the septic tank for harmless treatment, the fecal residue is applied back to the vegetable plots and farmlands. The fecal liquid in the third compartment of the septic tank is discharged into the ditch in the village through the household sewage collection pipe. Secondly, the original greywater pipelines of each household are integrated and connected to the greywater treatment device. The diameter of the connecting pipe is 300 mm, and the pipe material is PVC. The outlet of the treated greywater is connected to the nearest branch canal, and the volume of the greywater treatment device is 1 cubic meter.

[0084] There is already 1 natural ditch here. Farmers are scattered on both sides of the ditch. There are farmers at three places A, B, and D on the north side of the ditch, and farmers at place C on the south side of the ditch. While transforming the natural ditch, ditches are built at four places A, B, C, and D. The ditch in the village is 3 km long, 0.8 m wide, and 0.5 m high. The ditch is treated with anti-seepage using film material and concrete, and 9 ecological treatment modules are placed. The ditch outside the village is built using the natural ditch. After trimming, it is 2 m wide, 1 m high, and 1 km long. The sewage flows directly into the farmland and wasteland after passing through the ditch outside the village. The side wall of the ditch uses grass grid bricks, and 3 ecological treatment modules are placed.

[0085] The ecological treatment module in the village is 0.5 m wide and 1 m long. The height of the movable screen is 0.15 m, the length of the sedimentation device is 0.15 m, and the depth is 0.2 m; the purification and adsorption device is 0.3 m long and 0.15 m high; the plant purification tank is 0.15 m long and 0.2 m deep.

[0086] The ecological treatment module outside the village is 2 m wide and 1.5 m long. The height of the movable screen is 0.3 m, the length of the sedimentation device is 0.2 m, and the depth is 0.4 m; the purification and adsorption device is 0.6 m long and 0.3 m high; the plant purification tank is 0.2 m long and 0.4 m deep.

[0087] The plant unit plants submerged plants Myriophyllum spicatum and Hydrilla verticillata, with a planting density of 10 plants / m 2 and emergent plants Typha orientalis and Phragmites australis, with a planting density of 4 plants / m 2

[0088] The three-layer filling tank of the purification and adsorption device is filled with ceramsite, quartz sand, and vermiculite from top to bottom.

[0089] After determining the operation for 30 days, samples are taken and tested at different positions (such as the outlet of the greywater treatment device, the inlet of the ditch outside the village, and the downstream of the ditch outside the village). The test results are shown in Table 2 below.

[0090] Table 2 Water quality indicators after treatment by the rural domestic sewage treatment system and method in the small watershed

[0091] Pollutant type Outlet grey water Inlet of the ditch outside the village Downstream of the ditch outside the village COD (mg / l) 93 65 32 Ammonia nitrogen (mg / l) 8.0 3.6 1.1 Total phosphorus (mg / l) 2.9 1.4 0.3

[0092] It can be seen from the greywater treatment indicators shown in Table 2 that the rural domestic sewage treatment system and method provided by the present invention can significantly reduce the sewage concentration, achieve a virtuous cycle of water resources and organic waste in rural areas, have low operating costs, and good ecological properties.

[0093] The above are only specific embodiments of the present invention, enabling those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments described herein, but rather will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for treating rural domestic sewage in a small watershed, characterized in that, The method includes the following steps: (1) Black water and grey water separation: Collect and treat black water and grey water separately in the farmer's courtyard; The collected black water is first discharged into the septic tank for harmless treatment. The manure residue is directly diluted for use or produced into organic fertilizer for resource utilization. The manure liquid in the third compartment of the septic tank is discharged into the ditch outside the courtyard through the farmer's sewage collection pipe, or reused in the small gardens, vegetable gardens, and orchards in front of and behind the house. The collected grey water is discharged into the ditch after being treated by the grey water treatment device; (2) Ditch treatment: Transform the ditch so that the wastewater discharged into the ditch flows through more than one ecological treatment module for deep purification; (3) Reclaimed water utilization: The up-to-standard reclaimed water obtained after being treated by the ecological treatment module system is discharged or used for farmland irrigation to achieve the resource utilization of reclaimed water; The treatment method is carried out by using a rural domestic sewage treatment system for small watersheds. The rural domestic sewage treatment system for small watersheds includes a grey water treatment device and an ecological treatment module; The grey water treatment device is provided with an inlet (1) and an outlet (7). The grey water treatment device and the ecological treatment module are connected through the outlet (7). The grey water treatment device includes a filtration chamber and a sedimentation chamber (6). The filtration chamber and the sedimentation chamber (6) are separated by a first partition plate (15). A first overflow port (5) connecting the filtration chamber and the sedimentation chamber (6) is arranged on the first partition plate (15). The inlet (1) is connected to the upper section of the filtration chamber, and the outlet (7) is connected to the upper section of the sedimentation chamber (6). A pair of first oil-absorbing cotton (31) are both inclined in the filtration chamber; The grey water treatment device further includes a grid screen (2) arranged at the inlet (1). The grid screen (2) is horizontally arranged above the first oil-absorbing cotton (31). One side of the grid screen (2) is connected to the inner wall of the filtration chamber. The end of the grid screen (2) far from the inlet (1) is connected to the upper end of the first oil-absorbing cotton (31) close to the inlet (1). The upper end of the first oil-absorbing cotton (31) close to the inlet (1) is connected to the top of the filtration chamber through a baffle (17); The filtration chamber is divided into three filtration cavities along the water flow direction; A second partition plate (18) is arranged between the pair of first oil-absorbing cotton. The second partition plate (18) separates the pair of first oil-absorbing cotton (31), and a second overflow port (19) is opened on the second partition plate (18); The ecological treatment module includes a bottom plate (16) and a purification component. The bottom plate (16) is arranged in a ditch (14), and the purification component is arranged on the bottom plate (16). A first clamping structure and a second clamping structure for clamping and matching are respectively arranged at the front end and the rear end of the bottom plate (16). Multiple bottom plates (16) are connected end to end through the first clamping structure and the second clamping structure. The purification component includes a sedimentation tank (10), a purification and adsorption device (11), and a plant purification tank (13) arranged in sequence along the water flow direction. Three grooves are arranged on the bottom plate (16) and embedded in the bottom of the ditch (14). The sedimentation tank (10), the purification and adsorption device (11), and the plant purification tank (13) are respectively arranged in the three grooves. The upper section of the purification and adsorption device (11) extends upward to a height higher than the bottom of the ditch (14). The purification and adsorption device (11) includes three layers of filling grooves, and three kinds of purification materials are respectively filled in the three layers of filling grooves. The purification materials are selected from one of zeolite, ceramsite, quartz sand, vermiculite, steel slag, or blast furnace slag. Biological film hanging suspension fillers are arranged in the sedimentation tank, and plant units are arranged in the plant purification tank.

2. The method according to claim 1, characterized in that, The first clamping structure and the second clamping structure are respectively a clamping groove (161) and a clamping buckle (162). A screen (8) is arranged at the clamping groove (161). The screen (8) is slidably inserted into the clamping groove (161) in the vertical direction. Two bottom plates (16) are seamlessly connected through the clamping groove (161) and the clamping buckle (162).

3. The method according to claim 1, characterized in that, The plant units are emergent plants and / or submerged plants.

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