Unpowered anti-clogging constructed wetland system for treating rural domestic sewage and treatment process

Abstract

This invention discloses a non-powered, anti-clogging constructed wetland treatment system and process for rural domestic sewage, comprising: a grit chamber, a septic tank, a hydrolysis acidification tank, and an anti-clogging subsurface flow constructed wetland arranged sequentially from high to low; the anti-clogging subsurface flow constructed wetland comprises: multiple wetland units distributed in a stepped manner; this invention is applicable to rural domestic sewage treatment, and by creating a water level difference and a potential energy and kinetic energy conversion mechanism, sewage purification can be achieved without the need for external power, effectively removing COD, ammonia nitrogen, and total phosphorus from sewage, and has the characteristics of low energy consumption, high efficiency, anti-clogging, and easy maintenance.

Description

Technical Field

[0001] This invention relates to the field of environmental wastewater treatment technology, and more specifically to a non-powered, anti-clogging constructed wetland treatment system and process for rural domestic wastewater. Background Technology

[0002] With rapid economic and social development, the amount of domestic sewage generated in rural areas of my country has been increasing daily in recent years. Statistics show that the national minimum amount of domestic sewage generated in rural areas increased from 7.469 billion cubic meters in 2013. 3 Increased to 11.037 billion m³ in 2019. 3 An increase of 3.668 billion m 3 The upper limit of production increased from 11.204 billion cubic meters in 2013. 3 Increased to 16.556 billion m³ in 2019. 3 An increase of 5.352 billion m 3 The total growth rate from 2013 to 2019 was 47.78%, with an average annual growth rate of 6.83%. However, due to constraints from various factors such as economy, technology, and cultural habits, domestic sewage in most rural areas of my country has long been discharged indiscriminately without effective treatment measures. Even in a few areas where simple treatment is implemented, it is difficult to achieve discharge standards. Survey data shows that in 2019, the treatment rate of rural domestic sewage was approximately 31.50%, far lower than that of urban areas (96.81%). The disorderly discharge of rural domestic sewage seriously damages rural water environment safety, hinders the construction of rural living environment, and poses a significant threat to the physical and mental health of villagers. The problem of rural domestic sewage treatment urgently needs to be solved.

[0003] In most rural areas of my country, the population is scattered and the level of urbanization is low, resulting in domestic sewage being characterized by dispersed discharge, small volume, and large fluctuations. At the same time, rural areas are constrained by shortcomings such as a lack of funds, a shortage of technical personnel, and loose management, resulting in problems such as the long-term inadequacy of rural purification facilities, unreasonable construction processes, and unscientific maintenance. Therefore, the development of a green, low-carbon, low-cost, and efficient rural domestic sewage treatment process has become an urgent need.

[0004] Currently, constructed wetlands are a proven and effective ecological treatment method for water purification, widely used in rural areas. However, traditional constructed wetland processes are structurally simple, with generally limited treatment efficiency, and are less effective at handling complex pollutant types and high concentrations of domestic sewage. Furthermore, maintaining stable operation of constructed wetlands typically requires external power, increasing costs. Because of the long-term exposure to highly polluted water bodies, the deposition of solid pollutants and the adhesion of microbial films easily lead to clogging of the wetland substrate. This clogging is exacerbated by the growth and spread of plant roots.

[0005] Patent CN214299508U describes an anti-clogging constructed wetland device. It constructs a multi-chamber anti-clogging device that uses the siphon principle to guide water flow to backwash the clogged constructed wetland. However, this device has a complex manufacturing process, is not easy to manufacture and maintain, and the backwash water is easily dissipated by the packing material, so it can only be used in a very limited range.

[0006] Patent CN 215365378U describes a variable load anti-clogging constructed wetland water purification structure. This invention designs a set of motor devices to clean the adhering pollutants on the substrate to achieve the anti-clogging function. However, this device relies on external electric machinery, which is costly, difficult to maintain, and hard to promote and apply.

[0007] Patent CN 216038857U describes a clog-resistant, detachable composite vertical flow constructed wetland system. This invention designs a drawer-type structure for loading filler to construct a multi-layer structure of constructed wetland. However, if the filler in the drawer becomes clogged, all the filler in the entire structure needs to be replaced, which consumes a lot of manpower and resources and is difficult to maintain.

[0008] Patent 111233275A describes a composite rural sewage treatment device, which consists of a bar screen, an oil separator, a primary constructed wetland, and a secondary constructed wetland connected in sequence. It can improve sewage purification efficiency, but this device can only reduce the probability of clogging, not prevent clogging from occurring.

[0009] Therefore, how to provide a non-powered, anti-clogging constructed wetland treatment system and process suitable for rural domestic sewage treatment is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0010] In view of this, the present invention provides a non-powered anti-clogging constructed wetland treatment system and process for rural domestic sewage, which can be applied to the purification of rural domestic sewage. It can alleviate the problem of easy clogging of constructed wetlands under long-term operation without power, enhance the purification efficiency of constructed wetlands, reduce the management and maintenance costs of constructed wetlands, and realize cost-effectiveness in the entire process of rural domestic sewage treatment.

[0011] To achieve the above objectives, the present invention adopts the following technical solution:

[0012] A non-powered, anti-clogging constructed wetland treatment system for rural domestic sewage includes: a grit chamber, a septic tank, a hydrolysis acidification tank, and an anti-clogging subsurface flow constructed wetland arranged in a series of interconnected components from high to low.

[0013] The anti-clogging subsurface flow constructed wetland comprises multiple wetland units distributed in a stepped manner.

[0014] The beneficial effect of the above technical solution is that the combination of the above four parts forms a height difference, and the water’s gravitational potential energy forms a waterfall, which can operate automatically without the need for other external power conditions (electricity, machinery).

[0015] Preferably, the rural domestic sewage non-powered anti-clogging constructed wetland treatment system further includes: a black and ash separation module.

[0016] The black and gray separation module is connected to the bar screen sedimentation tank.

[0017] Preferably, the grit chamber is divided into a black water zone and a grey water zone by a partition wall;

[0018] The black water outlet of the black water separation module is connected to the black water inlet of the black water zone, and the black water outlet of the black water zone is connected to the septic tank.

[0019] The ash water outlet of the black ash separation module is connected to the ash water inlet of the ash water zone, and the ash water outlet of the ash water zone is connected to the hydrolysis acidification tank.

[0020] A sand-blocking wall is provided on the same side near the black water outlet and the gray water outlet, and an anti-blocking plate is provided between them;

[0021] The sand-blocking wall is equipped with a grid;

[0022] The top of the grit chamber is equipped with a baffle plate on the side near the black water inlet and the gray water inlet.

[0023] The isolation plate is a cement cover plate;

[0024] The top of the grit chamber is provided with an inspection port on the side near the black water outlet and the gray water outlet.

[0025] The black water mainly comes from the flushing water of farmers' toilets. It contains a mixture of diluted urine, feces and other pollutants, as well as other high-concentration domestic sewage. It is characterized by small water volume and high pollutant concentration.

[0026] The grey water refers to other domestic wastewater besides toilets, including sewage generated daily from kitchens, laundry, showers, washing, cleaning, etc., and is characterized by large volume and low pollution.

[0027] The beneficial effects of the above technical solution are that it filters out large solid waste in black water through the grit chamber, reduces the volume of recalcitrant pollutants entering the septic tank, and improves the degradation efficiency of organic pollutants by microorganisms in the septic tank.

[0028] Preferably, the septic tank includes a primary aerobic fermentation tank, a secondary anaerobic treatment tank, and a tertiary clarification treatment tank;

[0029] The black water outlet of the grit chamber extends to the lower middle part of the primary aerobic fermentation tank.

[0030] A guide pipe is provided between the primary aerobic fermentation tank and the secondary anaerobic treatment tank, and between the secondary anaerobic treatment tank and the tertiary clarification treatment tank;

[0031] An outlet pipe is provided on the other side wall of the three-stage clarification treatment tank and is connected to the hydrolysis acidification tank.

[0032] Preferably, the top of the primary aerobic fermentation tank is provided with an isolation net and the bottom is provided with a filter layer; the isolation net is wire mesh; the filter layer is straw bedding material with a thickness of 20-30cm.

[0033] The bottom of the secondary anaerobic treatment tank is provided with an anaerobic sludge layer with a thickness of 10-20cm;

[0034] Both the secondary anaerobic treatment tank and the tertiary clarification treatment tank are covered with a second isolation plate.

[0035] The second isolation plate is provided with inspection holes for dredging and inspection;

[0036] The second isolation panel is a concrete baffle.

[0037] The beneficial effects of the above technical solution are that the septic tank achieves interception and degradation of a large number of recalcitrant organic pollutants in black water through aerobic and anaerobic fermentation, which alleviates the working pressure of the hydrolysis acidification tank and promotes its working efficiency. At the same time, since pollutants are prone to form sediment after mixing with bedding material and sludge, they can be cleaned through inspection holes when they accumulate to a certain extent. The straw bedding material combines with sewage, particulate pollutants and microorganisms, and after microbial fermentation, it forms highly expanded aggregates at the bottom of the fermentation tank. Under the pressure of the tank bottom and walls, it is fixed at the bottom and will not rise with the water level.

[0038] Preferably, the hydrolysis acidification tank is divided into a packing layer, a suspended layer and a sludge layer from top to bottom;

[0039] The packing layer is provided with several parallel supports, and the packing is suspended on the supports; the packing is a packing with a high specific surface area.

[0040] The suspended layer is a transitional layer between the packing layer and the sludge layer. It is formed by the diffusion of microorganisms from the upper packing layer and the lower sludge layer, and is the region with the highest microbial species diversity and functional complexity.

[0041] The sludge layer consists of a water distribution network and activated sludge. The activated sludge is 10-15cm thick. The outlet of the water distribution network is more than 5cm higher than the surface of the activated sludge. The sludge replacement time is 6-12 months.

[0042] The bottom of the sludge layer is also provided with an inlet pipe, which is connected to the ash water outlet of the grit chamber and the outlet pipe on the side wall of the three-stage clarification treatment tank, respectively.

[0043] The inlet pipe of the sludge layer is connected to the water distribution network;

[0044] The top of the packing layer is provided with a water outlet, an exhaust pipe, and a detection port.

[0045] The beneficial effects of the above technical solution are that, in the hydrolysis and acidification tank, the refractory organic matter in rural domestic sewage is hydrolyzed and acidified by anaerobic and facultative bacteria, which decomposes the suspended organic solids and refractory macromolecules in the sewage into soluble organic matter and easily biodegradable small molecules; the activated sludge has a higher density than water and is often in a sedimentation state in water, and the outlet of the water distribution network sprays water upward, which can effectively prevent sludge from clogging the outlet.

[0046] Preferably, the anti-clogging subsurface flow constructed wetland includes a filter oxygenation tank, a plant planting module, and a perforated overflow plate;

[0047] The filtration and oxygenation tank is connected to the outlet at the top of the packing layer;

[0048] A cavity is provided between the filter oxygenation tank and the first perforated overflow plate;

[0049] The perforated overflow plates are arranged in groups of 2 to 3, forming a wetland unit with the same height. Each wetland unit includes 4 to 12 plant planting modules.

[0050] Preferably, the filter oxygenation tank is covered with gravel with a particle size of 4-6 cm; the filter oxygenation tank is provided with water flow holes with a diameter of 3 cm.

[0051] The beneficial effects of the above technical solution are that the gravel layer can effectively isolate solid particles entering the constructed wetland, preventing the accumulation of pollutants in the constructed wetland and causing blockage. At the same time, the irregular shape and accumulation pattern of the gravel force the water flow to form turbulence, increasing the contact area between the water and the air, which increases the dissolved oxygen content of the sewage before it enters the constructed wetland.

[0052] The plant planting module is composed of expanded clay aggregate-concrete blocks and PVC pipe-plant planting tubes;

[0053] The expanded clay aggregate-concrete block has a rectangular structure with an inner cavity in the middle; the particle size of the expanded clay aggregate is 5-10mm.

[0054] The PVC pipe-planting tube is installed inside the cavity of the expanded clay-concrete block;

[0055] The PVC pipe-plant planting cylinder has evenly distributed water passage holes on its body;

[0056] The PVC pipe-planting cylinder is filled with fine granular filler wrapped in gauze; the fine granular filler includes, but is not limited to, zeolite and quartz sand.

[0057] The fine-particle filler is planted with single, single-clump, or single-swarm purification plants; the purification plants include, but are not limited to, native plants with strong comprehensive decontamination ability, cold and heat resistance, and good disease and pest resistance, such as canna lily, reed, reed, thalia elata, windmill grass, and vetiver grass.

[0058] The beneficial effects of the above technical solution are that, due to the large pore size of the expanded clay granules, they have strong water and air permeability and are stable and firm, providing stable water flow and strong support for the planting cylinder placed in the inner cavity; at the same time, after long-term operation, when local blockage is caused by plant root growth and metabolism or water quality, the planting cylinder can be manually removed, the plants can be harvested as a whole, and the filling material inside the cylinder can be replaced or rinsed and dried for reuse, thus achieving the anti-blocking function.

[0059] The perforated overflow plate is made of cast concrete slab;

[0060] The perforated overflow plate has water perforations arranged alternately at the top and bottom;

[0061] The diameter and number of the water-permeable holes should be such that they allow water to pass through to the maximum extent possible without compromising the rigidity of the concrete slab.

[0062] The beneficial effects of the above technical solution are that, on the one hand, the perforated overflow plate can increase the probability of water flow contacting air, increase the oxygen content of the water flow, improve the activity of aerobic microorganisms in the packing layer, and enhance the pollutant removal rate; on the other hand, it can increase the contact opportunities between water flow and matrix packing, thereby improving the working efficiency of constructed wetlands; at the same time, the height is gradually reduced with the direction of water flow, controlling the water flow to form an upward / downward composite vertical flow and achieving overflow.

[0063] Preferably, coarse particles or a single type of filler are laid between the plant planting modules;

[0064] The filler includes, but is not limited to, gravel, crushed stone, and blast furnace slag.

[0065] The beneficial effect of the above technical solution is that by laying the packing material to filter the water flow, it provides a growth carrier for microorganisms, and because of its large particle size and single type, it is not easy to cause blockage during long-term operation.

[0066] A wastewater treatment process for a non-powered, anti-clogging constructed wetland system for rural domestic sewage treatment includes the following steps:

[0067] (1) Domestic sewage is discharged into the black and gray separation module for black water and gray water separation. The separated black water and gray water are discharged into the black water inlet and gray water inlet respectively and flow into the grit chamber. The black water enters the grit chamber, filters out large solid waste, and is discharged into the primary aerobic fermentation tank through the black water outlet. The gray water enters the grit chamber and is discharged into the sludge layer through the gray water outlet of the grit chamber.

[0068] (2) After the black water enters the primary aerobic fermentation tank, EM bacteria are added to the primary aerobic fermentation tank through the isolation net. After flowing through the secondary anaerobic treatment tank and the tertiary clarification treatment tank through the guide pipe, it is discharged through the effluent pipe on the side wall of the tertiary clarification treatment tank.

[0069] (3) The grey water and the black water discharged from the tertiary clarification treatment tank enter the water distribution network through the inlet pipe of the sludge layer. After passing through the suspended layer and the packing layer for microbial treatment, they are discharged after staying for 6-12 hours.

[0070] (4) Wastewater discharged through the packing layer enters the filtration and oxygenation tank for filtration and oxygenation. Wastewater flows out through the water passage on the filtration and oxygenation tank and enters the wetland unit at the highest position of the subsurface flow constructed wetland through the water passage on the perforated overflow plate. It forms a composite vertical flow state with alternating upward and downward flow through the water passage on the overflow plate. After being purified by multiple wetland units, it is discharged in compliance with standards.

[0071] The beneficial effects of the above technical solutions are as follows: the separation of black, gray and water reduces the amount and difficulty of pollutant treatment in subsequent stages; the tertiary treatment of septic tanks achieves primary interception and initial degradation of recalcitrant organic pollutants through aerobic and anaerobic fermentation; the acidification and hydrolysis tank further decomposes and dissociates recalcitrant organic pollutants into easily treatable small molecule organic matter; and the multiple modules of the constructed wetland amplify the degradation effect of microorganisms through the combined effect, thus promoting water purification efficiency.

[0072] Preferably, in step (2), the ratio of EM microbial agent to straw bedding material is 1:100, that is, 1 kg of microbial agent is used for 100 kg of straw bedding material;

[0073] Preferably, the residence time of wastewater in the hydrolysis acidification tank in step (3) can be adjusted according to the degree of pollution and the season.

[0074] The beneficial effects of the above technical solution are: increasing the abundance and diversity of highly efficient microorganisms, promoting microbial fermentation efficiency, improving the degradation efficiency of organic pollutants, appropriately extending the residence time for heavily polluted water bodies and seasons with low temperatures, increasing the microbial reaction time, achieving effective purification of heavily polluted water bodies, and mitigating the negative impact of low temperature environment on microbial biochemical reactions.

[0075] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a non-powered anti-clogging constructed wetland treatment process for rural domestic sewage, which has the following beneficial effects:

[0076] 1. Low energy consumption: The entire system achieves free flow of water in all stages by creating a water level difference and a potential energy and kinetic energy conversion mechanism. It can purify sewage without the need for external power such as electricity or fuel, making it a green and low-carbon sewage treatment method.

[0077] 2. High efficiency: The entire system is designed with four key links to gradually purify rural domestic sewage. Through the orderly cooperation and synergistic effect of different types of substrates and various microorganisms in multiple links, multiple types of pollutants in the water are intercepted, and high-concentration pollutants are significantly reduced, which effectively promotes the standard discharge of rural domestic sewage.

[0078] 3. Anti-clogging: The entire system efficiently intercepts and purifies rural domestic sewage through a grit chamber, septic tank, and hydrolysis acidification tank, removing the vast majority of solid particulate pollutants and ensuring that sewage is less prone to clogging after flowing into the subsurface flow constructed wetland. Simultaneously, the traditional subsurface flow constructed wetland structure is upgraded and transformed, constructing a new type of subsurface flow constructed wetland with plant planting modules as the core. Simple plant pruning and filler replacement easily ensure long-term, clog-free operation of the constructed wetland.

[0079] 4. Easy to maintain: Since the entire system does not use external power equipment, no additional maintenance or repair is required. Furthermore, because it uses plant modules as the core of the constructed wetland, only simple periodic pruning of the plants and simple replacement or recycling and cleaning of the filler material are needed to ensure the long-term operation of the constructed wetland. Attached Figure Description

[0080] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0081] Figure 1 This is a process flow diagram of the present invention;

[0082] Figure 2 This is a schematic diagram of the grit chamber structure of the present invention;

[0083] Figure 3 This is a schematic diagram of the septic tank structure of the present invention;

[0084] Figure 4This is a schematic diagram of the hydrolysis acidification tank structure of the present invention;

[0085] Figure 5 This is a schematic diagram of the anti-clogging undercurrent constructed wetland structure of the present invention;

[0086] Figure 6 This is a schematic diagram of the filter oxygenation tank structure of the present invention;

[0087] Figure 7 This is a schematic diagram of the plant planting module structure of the present invention;

[0088] Figure 8 This is a schematic diagram of the perforated overflow plate structure of the present invention;

[0089] In the diagram, 1-grit settling tank, 11-partition wall, 12-black water zone, 121-black water inlet, 122-black water outlet, 13-grey water zone, 131-grey water inlet, 132-grey water outlet, 14-sand retaining wall, 15-grit, 16-anti-clogging plate, 17-isolation plate one, 18-inspection port, 2-septic tank, 21-primary aerobic fermentation tank, 211-isolation net, 212-EM agent, 213-filter layer, 214-diversion pipe, 22-secondary anaerobic treatment tank, 221-anaerobic sludge layer, 222-isolation plate two, 223-inspection hole, 23-tertiary clarification tank, 231-effluent pipe, 3-hydrolysis acidification tank, 31-packing layer, 3 11-Filling material, 312-Support, 313-Outlet, 314-Exhaust pipe, 315-Detection port, 32-Suspended layer, 33-Sludge layer, 331-Water distribution network, 332-Activated sludge, 333-Inlet pipe, 4-Anti-clogging subsurface flow constructed wetland, 41-Filtering and sampling tank, 411-Cavity, 412-Gravel, 413-Water flow hole, 42-Plant planting module, 421-Ceramic aggregate-concrete block, 4211-Inner cavity, 4212-Ceramic aggregate, 422-PVC pipe-plant planting cylinder, 4221-Water passage hole, 4222-Fine particle filler, 4223-Purifying plant, 43-Perforated overflow plate, 431-Water passage hole, 44-Coarse particle filler. Detailed Implementation

[0090] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0091] Example

[0092] The present invention provides a non-powered, anti-clogging constructed wetland treatment system for rural domestic sewage, comprising: a grit chamber, a septic tank, a hydrolysis acidification tank, and an anti-clogging subsurface flow constructed wetland arranged in a sequence from high to low.

[0093] It also includes: a black and gray processing module.

[0094] The black and gray separation module is connected to the grit chamber 1;

[0095] The grit chamber 1 is divided into a black water zone 12 and a grey water zone 13 by a partition wall 11;

[0096] The black water outlet of the black water separation module is connected to the black water inlet 121 of the black water zone 12, and the black water outlet 122 of the black water zone 12 is connected to the septic tank 2.

[0097] The ash water outlet of the black ash separation module is connected to the ash water inlet 131 of the ash water zone 13, and the ash water outlet 132 of the ash water zone 13 is connected to the hydrolysis acidification tank 3.

[0098] A sand-blocking wall 14 is provided on the same side near the black water outlet 122 and the gray water outlet 132, and an anti-blocking plate 16 is provided between them.

[0099] The sand retaining wall 14 is equipped with a grid 15;

[0100] A partition plate 17 is provided on the top of the grit chamber 1 near the black water inlet 121 and the gray water inlet 131. The partition plate 17 is a cement cover plate.

[0101] An inspection port 18 is provided on the top of the grit chamber 1 near the black water outlet 122 and the gray water outlet 132.

[0102] Septic tank 2 includes a primary aerobic fermentation tank 21, a secondary anaerobic treatment tank 22, and a tertiary clarification treatment tank 23;

[0103] The black water outlet end 122 of the grit chamber 1 extends to the middle and lower part of the primary aerobic fermentation tank 21;

[0104] A guide pipe 214 is provided between the primary aerobic fermentation tank 21 and the secondary anaerobic treatment tank 22, and between the secondary anaerobic treatment tank 22 and the tertiary clarification treatment tank 23;

[0105] A water outlet pipe 231 is provided on the other side wall of the three-stage clarification treatment tank 23, and is connected to the hydrolysis acidification tank 3.

[0106] The top of the primary aerobic fermentation tank 21 is equipped with an isolation net 211, which is made of wire mesh, and the bottom is equipped with a filter layer 213, which is made of straw bedding material with a thickness of 30cm.

[0107] The bottom of the secondary anaerobic treatment tank 22 is provided with an anaerobic sludge layer 221 with a thickness of 20cm;

[0108] Both the secondary anaerobic treatment tank 22 and the tertiary clarification treatment tank 23 are covered with a second isolation plate 222, which is a concrete baffle.

[0109] Inspection holes 223 are provided on the concrete baffle;

[0110] The hydrolysis acidification tank 3 is divided into a packing layer 31, a suspended layer 32 and a sludge layer 33 from top to bottom;

[0111] The packing layer 31 is provided with several parallel supports 312, and the packing 311 is suspended on the supports 312. The packing 311 is a packing with a high specific surface area.

[0112] The suspended layer 32 is a transitional layer between the packing layer 31 and the sludge layer 33. It is formed by the diffusion of microorganisms from the upper packing layer and the lower sludge layer, and is the area with the highest microbial species diversity and functional complexity.

[0113] The sludge layer 33 consists of a water distribution network 331 and activated sludge 332. The activated sludge 332 is 10cm thick, the outlet of the water distribution network 331 is 20cm high, and the activated sludge 332 is replaced every 6 months.

[0114] The bottom of the sludge layer 33 is also equipped with an inlet pipe 333, which is connected to the gray water outlet end 132 of the grit chamber and the outlet pipe 231 on the side wall of the tertiary clarification treatment tank 23 respectively.

[0115] The inlet pipe 333 of the sludge layer 33 is connected to the water distribution network 331;

[0116] The top of the packing layer 31 is provided with an outlet 313, an exhaust pipe 314 and an inspection port 315.

[0117] The anti-clogging subsurface flow constructed wetland 4 includes a filter and oxygenation tank 41, a plant planting module 42, and a perforated overflow plate 43;

[0118] The filter oxygenation tank 41 is connected to the outlet 313 at the top of the packing layer 31;

[0119] A cavity 411 is provided between the filter oxygenation tank 41 and the first perforated overflow plate 43;

[0120] The perforated overflow plate 43 consists of 3 plates forming a wetland unit with the same height, and each wetland unit includes 12 plant planting modules 42;

[0121] Coarse-gravel filler 44 is laid between the plant planting modules 42;

[0122] The filter oxygenation tank 41 is covered with gravel 412, the gravel 412 has a particle size of 5cm; the filter oxygenation tank 41 is provided with water flow holes 413, the hole diameter is 3cm.

[0123] The plant planting module 42 is composed of expanded clay aggregate-concrete blocks 421 and PVC pipe-plant planting tubes 422;

[0124] The expanded clay aggregate-concrete block 421 has a rectangular parallelepiped structure with an inner cavity 4211 in the middle; the expanded clay aggregate 4212 has a particle size of 10mm;

[0125] The PVC pipe-planting tube 422 is installed in the inner cavity 4211 of the expanded clay-concrete block;

[0126] The PVC pipe-planting tube 422 has evenly distributed water passage holes 4221 on its body;

[0127] The PVC pipe planter is filled with fine granular filler 4222 zeolite wrapped in gauze, and a single purification plant 4223 canna is planted on the zeolite.

[0128] The perforated overflow plate 43 is made of cast concrete slab;

[0129] The perforated overflow plate 43 has water perforations 431 arranged alternately at the top and bottom;

[0130] The diameter of the water-permeable hole 431 is 3cm, and the number is 10 / meter.

[0131] A treatment process for a non-powered, anti-clogging constructed wetland system for rural domestic sewage includes the following steps:

[0132] (1) Domestic sewage is discharged into the black and gray separation module for black water and gray water separation. The separated black water and gray water are discharged into the black stone inlet and gray water inlet respectively and flow into the grit chamber. The black water enters the grit chamber, filters out large solid waste, and is discharged into the lower part of the primary aerobic fermentation tank through the black water outlet. The gray water enters the grit chamber and is discharged into the sludge layer through the gray water outlet of the grit chamber.

[0133] (2) After the black water enters the primary aerobic fermentation tank, EM bacteria are added to the primary aerobic fermentation tank through the isolation net. After the reaction, the black water flows through the secondary anaerobic treatment tank and the tertiary clarification treatment tank through the guide pipe and is discharged through the effluent pipe.

[0134] (3) The grey water and the black water discharged from the clarification treatment tank enter the water distribution network through the inlet pipe of the sludge layer, and are treated by microorganisms in sequence through the suspended layer and the packing layer. After staying for 6 hours, they are discharged.

[0135] (4) Wastewater discharged from the packing layer enters the filtration and oxygenation tank for filtration and oxygenation. The wastewater flows out through the water passage on the filtration and oxygenation tank and enters the wetland unit at the highest position of the subsurface flow constructed wetland through the water passage on the perforated overflow plate. It forms a composite vertical flow state with alternating upward and downward flow through the water passage on the overflow plate. After being purified by multiple wetland units, it is discharged in compliance with standards.

[0136] The amount of EM microbial agent added is 0.5 kg, and the weight of the straw bedding material is 50 kg.

[0137] Wastewater treatment results

[0138] The non-powered anti-clogging constructed wetland treatment system and process for rural domestic sewage provided in the embodiment were implemented in Xinqi Village, Foshan City. It successfully achieved non-powered operation for two years by utilizing hydraulic gradient, with no clogging occurring. The aquatic vegetation coverage remained at 100% year-round, and the water purification effect was significant. The results are shown in Table 1.

[0139] COD ammonia nitrogen Total phosphorus Before treatment (mg / L) 55.6 17.74 1.4 After treatment (mg / L) 25.8 0.724 0.114 Removal rate (%) 53.6％ 95.9％ 91.9％

[0140] Table 1

[0141] As shown in Table 1, the non-powered anti-clogging constructed wetland treatment system and process for rural domestic sewage of the present invention can effectively treat rural domestic sewage, with a COD removal rate of 53.6%, an ammonia nitrogen removal rate of 95.9%, and a total phosphorus removal rate of 91.9%.

[0142] Comparative Example 1

[0143] After two years of operation, the traditional subsurface flow constructed wetland used for purifying rural domestic sewage in Mazaibei Village, Yangjiang City, experienced severe blockage, resulting in poor water purification efficiency. The removal rates of COD, ammonia nitrogen, and total phosphorus were 25.5%, 27.8%, and 0.8%, respectively.

[0144] Energy consumption and cost comparison

[0145] The present invention embodiments are compared with the energy consumption and cost of constructed wetlands using the A2O process driven by electricity. Under the premise of having the same wastewater treatment capacity, the energy consumption, construction cost and maintenance cost of the present invention are significantly lower, and it has obvious characteristics of low energy consumption, low cost and high efficiency. The results are shown in Table 2.

[0146] process Processing capacity Construction costs Energy consumption Operating costs Maintenance costs A2O Level A 10,000 yuan per household 1.2 degrees / ton 0.5 yuan / ton 20,000 yuan / year No power Level A 0.5 million yuan / household 0.03 degrees / ton 0.1 yuan / ton 0.3 million yuan / year

[0147] Table 2

[0148] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0149] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A non-powered, anti-clogging constructed wetland system for treating rural domestic sewage, characterized in that, include: The grit chamber, septic tank, hydrolysis acidification tank, and anti-clogging subsurface flow constructed wetland are connected in sequence from high to low. The anti-clogging undercurrent constructed wetland comprises multiple wetland units distributed in a stepped manner; It also includes: a black and gray separation module, which is connected to the grit chamber; The grit chamber is divided into a black water zone and a grey water zone by a partition wall. The black water outlet of the black-grey separation module is connected to the black water inlet of the black water zone, and the black water outlet of the black water zone is connected to the septic tank. The grey water outlet of the black-grey separation module is connected to the grey water inlet of the grey water zone, and the grey water outlet of the grey water zone is connected to the hydrolysis acidification tank. A sand-retaining wall is provided on the same side near the black water outlet and grey water outlet, and an anti-clogging plate is provided between them. A grit chamber is provided on the sand-retaining wall. An isolation plate is provided on the top of the grit chamber near the black water inlet and grey water inlet. An inspection port is provided on the top of the grit chamber near the black water outlet and grey water outlet. The septic tank includes a primary aerobic fermentation tank, a secondary anaerobic treatment tank, and a tertiary clarification tank; wherein, the black water outlet end of the grit chamber extends to the lower middle part of the primary aerobic fermentation tank; a guide pipe is provided between the primary aerobic fermentation tank and the secondary anaerobic treatment tank, and between the secondary anaerobic treatment tank and the tertiary clarification tank; an outlet pipe is provided on the other side wall of the tertiary clarification tank and connected to the hydrolysis acidification tank; The hydrolysis acidification tank is divided into a packing layer, a suspended layer, and a sludge layer from top to bottom. The packing layer has several parallel supports on which the packing material is suspended. The suspended layer is a transitional layer between the packing layer and the sludge layer, formed by the diffusion of microorganisms from the upper packing layer and the lower sludge layer; it is the area with the highest microbial species diversity and functional complexity. The sludge layer consists of a water distribution network and activated sludge, with a sludge replacement interval of 6-12 months. An inlet pipe is located at the bottom of the sludge layer, connecting to the grey water outlet of the grit chamber and the effluent pipe on the side wall of the tertiary clarification tank. The inlet pipe of the sludge layer is also connected to the water distribution network. An outlet is located at the top of the packing layer. The anti-clogging subsurface flow constructed wetland includes a filter and oxygenation tank, plant planting modules, and perforated overflow plates; wherein, the filter and oxygenation tank is connected to the outlet at the top of the packing layer; a cavity is provided between the filter and oxygenation tank and the first perforated overflow plate; every 2 to 3 perforated overflow plates form a wetland unit and are set at the same height, and each wetland unit includes 4 to 12 plant planting modules; The filter and oxygenation tank is lined with gravel and has water flow holes. The plant planting module consists of expanded clay aggregate-concrete blocks and PVC pipe-plant planting cylinders. The expanded clay aggregate-concrete blocks are rectangular with an inner cavity. The PVC pipe-plant planting cylinders are located within the inner cavity of the expanded clay aggregate-concrete blocks. The PVC pipe-plant planting cylinders have evenly distributed water flow holes. The PVC pipe-plant planting cylinders are filled with fine granular filler wrapped in gauze. Single, single clump, or single cluster of purification plants are planted on the fine granular filler. The perforated overflow plate is cast from a concrete slab. The perforated overflow plate has staggered water flow holes at the top and bottom. The diameter and number of the water flow holes are designed to maximize water flow without compromising the rigidity of the concrete slab.

2. The non-powered anti-clogging constructed wetland treatment system for rural domestic sewage according to claim 1, characterized in that, The top of the primary aerobic fermentation tank is equipped with an isolation net, and the bottom is equipped with a filter layer; The bottom of the secondary anaerobic treatment tank is provided with an anaerobic sludge layer; Both the secondary anaerobic treatment tank and the tertiary clarification treatment tank are covered with a second isolation plate. The second isolation plate is provided with inspection holes.

3. The wastewater treatment process of a non-powered anti-clogging constructed wetland treatment system for rural domestic sewage according to claim 1 or 2, characterized in that, Includes the following steps: (1) Domestic sewage is discharged into the black and gray separation module for black water and gray water separation. The separated black water and gray water are discharged into the black water inlet and gray water inlet respectively and flow into the grit chamber. The black water enters the grit chamber, filters out large solid waste, and is discharged into the primary aerobic fermentation tank through the black water outlet. The gray water enters the grit chamber and is discharged into the sludge layer through the gray water outlet of the grit chamber. (2) After the black water enters the primary aerobic fermentation tank, EM bacteria are added to the primary aerobic fermentation tank through the isolation net. After flowing through the secondary anaerobic treatment tank and the tertiary clarification treatment tank through the guide pipe, it is discharged through the effluent pipe on the side wall of the tertiary clarification treatment tank. (3) The grey water and the black water discharged from the tertiary clarification tank enter the water distribution network through the inlet pipe of the sludge layer, and are treated by microorganisms in sequence through the suspended layer and the packing layer. After staying for 6-12 hours, they are discharged. (4) Wastewater discharged from the packing layer enters the filtration and oxygenation tank for filtration and oxygenation. The wastewater flows out through the water passage on the filtration and oxygenation tank and enters the wetland unit at the highest position of the subsurface flow constructed wetland through the water passage on the perforated overflow plate. It forms a composite vertical flow state with alternating upward and downward flow through the water passage on the overflow plate. After being purified by multiple wetland units, it is discharged in compliance with standards.

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