Sewage treatment and gradient resource utilization system

Abstract

The invention discloses a sewage treatment and gradient resource utilization system. The system comprises a biological treatment unit and a fish and vegetable symbiosis unit connected with the biological treatment unit, the biological treatment unit comprises an anoxic tank and an aerobic tank connected with the anoxic tank, a sewage circulation part is arranged between the aerobic tank and the anoxic tank, and the sewage circulation part is used for adjusting the content of nitrogen and phosphorus in effluent of the aerobic tank to preset content values; the fish and vegetable symbiotic unit comprises a culture pond connected with the aerobic pond, economic crops which are produced by providing nutrition with nitrogen and phosphorus-rich sewage treated by the aerobic pond are cultivated at the top in the culture pond, the economic crops are cultivated according to a preset cultivation density, and a plurality of mixed ecological fishes are cultivated at the bottom in the culture pond. The multiple kinds of mixed ecological fishes are bred according to the preset breeding density, and the fishes comprise the fishes eating the root systems of the commercial crops and the fishes eating fish feces; compared with the prior art, resource utilization modes are diversified, economic benefits are high, the operation and maintenance cost is low, and energy consumption is low.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to a sewage treatment and cascade resource utilization system. Background Art

[0002] In order to promote the construction of healthy villages and continuously improve the rural living environment, rural domestic sewage treatment is of vital importance. Rural domestic sewage mainly includes feces and urine water (also known as black water), laundry water and kitchen water (collectively known as grey water). Its concentration is not high and the discharge volume is also small. However, if it is discharged indiscriminately for a long time, it will lead to the accumulation of a large amount of domestic sewage in the village, the clogging of ditches by debris, and the black and smelly water in the village and surrounding ponds and ditches, which will seriously affect rural construction.

[0003] The treatment of rural domestic sewage must be simple and effective, convenient for operation and maintenance, energy-saving and environmentally friendly, and generate economic benefits, so that it can truly enter the countryside and be accepted by farmers. In other words, the treatment of rural domestic sewage must follow the path of sustainable development, not only to treat the environment, but also to utilize resources to generate economic benefits, so as to truly help rural construction and increase farmers' production and income.

[0004] Sustainable rural domestic sewage treatment technology usually includes two parts: one is the biological unit, which mainly includes anaerobic units, anoxic units and aerobic units, mainly removing organic matter and some nitrogen and phosphorus substances; the other is the ecological unit, which mainly includes vegetable filter beds, artificial wetlands, multifunctional oxidation ponds and other processes, mainly through the cultivation of economic plants to achieve nitrogen and phosphorus resource utilization. For the biological unit, how to simplify it for easy maintenance and management and reduce energy consumption is worthy of attention; and for the ecological unit, how to maximize the resource utilization of sewage to achieve higher economic benefits is also worthy of attention. Only by solving the above problems can rural domestic sewage treatment be truly integrated into the "three rural" system and improve farmers' maintenance enthusiasm.

[0005] CN111196669A discloses a sewage treatment and nitrogen and phosphorus resource utilization system, which combines the characteristics of biological units and ecological units to treat and utilize sewage; specifically, it includes a pretreatment unit, the pretreatment unit includes a grid well and a regulating tank arranged at the water outlet of the grid well, the water inlet end of the grid well is provided with an inlet pipe for introducing sewage into the grid well, and the grid well is provided with a grid; after the pretreatment unit, a biological cage integrated unit and a tail water nitrogen and phosphorus absorption unit are arranged in sequence.

[0006] The biological cage integrated unit comprises an anoxic tank, an aerobic tank and a sedimentation tank which are arranged in sequence according to the water flow direction, wherein the anoxic tank and the sedimentation tank are provided with fiber bundle fillers; the aerobic tank is provided with a cage, wherein the cage comprises a filler cage and a rotating shaft, wherein the filler cage is an annular sandwich structure composed of concentric inner and outer cylinders, wherein the annular sandwich is filled with fillers, wherein the inner and outer cylinders are made of stainless steel and a plurality of through holes are arranged on the cylinder wall; the rotating shaft is arranged at the axial center of the filler cage, the rotating shaft is arranged horizontally and is perpendicular to the water flow direction, and the two ends of the rotating shaft are fixed on the wall of the aerobic tank through two bearings fixedly arranged on the two walls of the aerobic tank, and the filler cage is fixedly supported on the rotating shaft, so that part of the filler cage is located in the water body of the aerobic tank and part of it is exposed outside the water body; the rotating shaft is connected to a motor, so that the filler cage is driven to rotate by the motor; overflow weirs are arranged on the corresponding walls of the anoxic tank and the aerobic tank, so that the water body in the anoxic tank can enter the aerobic tank through the overflow weir, and the bottoms of the aerobic tank and the sedimentation tank are arranged in communication, so that the water body in the aerobic tank can enter the sedimentation tank from the bottom.

[0007] The tail water nitrogen and phosphorus absorption unit in the above-mentioned sewage treatment and nitrogen and phosphorus resource utilization system only absorbs nitrogen and phosphorus by cultivating economic crops, and has a single application. Summary of the invention

[0008] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a sewage treatment and cascade resource utilization system to solve the problem of single application in the prior art.

[0009] To achieve the above-mentioned object, the present invention adopts the following technical scheme: a sewage treatment and cascade resource utilization system, comprising a biological treatment unit and an aquaponics unit connected thereto;

[0010] The biological treatment unit includes an anoxic tank and an aerobic tank connected thereto, a sewage circulation part is arranged between the aerobic tank and the anoxic tank, and the sewage circulation part is used to adjust the nitrogen and phosphorus content in the effluent of the aerobic tank to a preset content value;

[0011] The fish-vegetable symbiotic unit includes a breeding pond connected to an aerobic pond, wherein economic crops produced by using nitrogen- and phosphorus-rich wastewater treated in the aerobic pond to provide nutrition are cultivated on the top of the breeding pond, and the economic crops are cultivated according to a preset cultivation density, and multiple species of mixed ecological fish are cultivated at the bottom of the breeding pond, and the multiple species of mixed ecological fish are cultivated according to a preset cultivation density and include fish that feed on the roots of economic crops and fish that feed on fish feces.

[0012] Technical principle:

[0013] Domestic sewage is treated in anoxic tanks and aerobic tanks, and a water cycle is formed between the sewage circulation part and the aerobic tank and anoxic tank to adjust the nitrogen and phosphorus content in the effluent from the aerobic tank to the preset content values; the treated sewage enters the breeding pond to provide the nutrients needed for the growth of economic crops cultivated in the breeding pond, and at the same time, a variety of ecological fish are raised in the breeding pond, including fish that feed on the roots of economic crops and fish that feed on fish feces, to coexist; and the nitrogen and phosphorus content in the effluent is adjusted to cooperate with the preset cultivation density of economic crops and the preset breeding density of ecological fish to ensure good fish-vegetable symbiosis, and also effectively remove the nitrogen and phosphorus content in the sewage to achieve an ecological symbiotic balance.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1. Diversified resource utilization methods and high economic benefits. By using the fish-vegetable symbiotic unit as the tailwater nitrogen and phosphorus absorption unit of the sewage treatment and cascade resource utilization system, ecological fish can be raised while cultivating cash crops. Not only can the cash crops be used to absorb nitrogen and phosphorus elements in the sewage, but different fish can also be reasonably raised in the breeding pond according to the preset breeding density to make full use of the roots of cash crops as food to achieve good symbiosis. Not only does it have the benefits brought by cash crops, but it also increases the benefits brought by ecological fish, and the economic benefits are greatly improved.

[0016] 2. Low operation and maintenance costs. First of all, cash crops and farmed ecological fish are integrated in the space where the breeding pond is located, which takes up little space and does not require too many water pipes to be laid, making operation and maintenance convenient.

[0017] 3. Low energy consumption. The water entering the breeding pond does not need to be disinfected. Instead, some microorganisms are needed to decompose the residual organic matter and fish feces in the sewage of the breeding pond, which reduces the energy consumption of the system; the water level of the breeding pond is easy to control, which reduces the burden on the biological treatment unit and also reduces energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A process flow chart of an embodiment of the present invention;

[0019] Figure 2 The structure of the pretreatment unit and the biological treatment unit in one embodiment of the present invention is shown in FIG. Figure 1 ;

[0020] Figure 3 The structure of the pretreatment unit and the biological treatment unit in one embodiment of the present invention is shown in FIG. Figure 2 ;

[0021] Figure 4 This is a schematic diagram of the structure of an aerobic pool in one embodiment of the present invention;

[0022] Figure 5This is a schematic diagram of the structure of a breeding pond in one embodiment of the present invention;

[0023] Figure 6 It is a schematic diagram of the arrangement of the step utilization unit in one embodiment of the present invention;

[0024] Figure 7 Schematic diagram of the structure of the grid well in one embodiment of the present invention.

[0025] The figure marks in the drawings of the specification include: anoxic tank 1, aerobic tank 2, sewage circulation part 3, annular cofferdam 31, fountain aerator 32, return weir 33, breeding pond 4, breeding hydroponic area 5, grille well 6, garbage collection chamber 61, front filter chamber 62, rear filter chamber 63, grille filter 64, slag guide port 65, anaerobic tank 7, clean water tank 8, limit cylinder 9, grid support assembly 10, lower grid plate 101, upper grid plate 102. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below through specific embodiments:

[0027] like Figure 1-Figure 7 As shown, an embodiment of the present invention proposes a sewage treatment and cascade resource utilization system, including a pretreatment unit, a biological treatment unit connected to the pretreatment unit, and a fish-vegetable symbiotic unit connected to the biological treatment unit; the biological treatment unit includes an anoxic tank 1 and an aerobic tank 2 connected thereto, a sewage circulation part 3 is arranged between the aerobic tank 2 and the anoxic tank 1, and the sewage circulation part 3 is used to adjust the nitrogen and phosphorus contents in the effluent of the aerobic tank 2 to a preset content value; the fish-vegetable symbiotic unit includes a breeding pond 4 connected to the aerobic tank 2, and the top of the breeding pond 4 is cultivated with economic crops produced by providing nutrition with sewage rich in nitrogen and phosphorus treated by the aerobic tank 2, and the economic crops are cultivated according to a preset cultivation density, and a plurality of species of mixed ecological fish are cultivated at the bottom of the breeding pond 4, and the plurality of species of mixed ecological fish are cultivated according to a preset cultivation density and include fish that feed on the roots of economic crops and fish that feed on fish feces.

[0028] When using:

[0029] Domestic sewage enters this sewage treatment and cascade resource utilization system, and is first pretreated by the pretreatment unit to intercept large particle impurities in the biological sewage. Then the domestic sewage enters the biological treatment unit for biological treatment to remove organic matter in the domestic sewage. However, the nitrogen and phosphorus content in the domestic sewage after treatment by the biological treatment unit is still relatively high and can only meet the irrigation standard. If there is no irrigated farmland to absorb it, tail water nitrogen and phosphorus absorption is required. Therefore, a fish-vegetable symbiosis unit is designed, and the domestic sewage then enters the fish-vegetable symbiosis unit to absorb nitrogen and phosphorus, providing the nutrients needed for the growth of economic crops and ecological fish symbiotic in the fish-vegetable symbiosis unit.

[0030] The sewage treatment and cascade resource utilization system has the following advantages: diversified resource utilization methods and high economic benefits. By using the fish-vegetable symbiotic unit as the tailwater nitrogen and phosphorus absorption unit of the sewage treatment and cascade resource utilization system, ecological fish can be cultivated while cultivating cash crops. Not only can the cash crops be used to absorb nitrogen and phosphorus elements in the sewage, but also different fish can be reasonably cultivated in the breeding pond 4 according to the preset breeding density to make full use of the roots of cash crops as food to carry out good symbiosis. It not only has the benefits brought by cash crops, but also increases the benefits brought by ecological fish, and the economic benefits are greatly improved. Low operation and maintenance costs. First of all, cash crops and farmed ecological fish are integrated in the space where the breeding pond 4 is located, occupying a small space, and do not need to lay too many water pipes, etc., which is convenient for operation and maintenance. Low energy consumption. The water entering the breeding pond 4 does not need to be disinfected and sterilized, but some microorganisms are needed to decompose the residual organic matter and fish feces in the sewage of the breeding pond 4, which reduces the energy consumption of the system; the water level of the breeding pond 4 is easy to control, which reduces the burden on the biological treatment unit and also reduces energy consumption.

[0031] Among them, a water cycle is also formed between the sewage circulation part 3 and the aerobic tank 2 and the anoxic tank 1 to adjust the nitrogen and phosphorus contents in the effluent of the aerobic tank 2 to the preset content values; in conjunction with the preset cultivation density of economic crops and the preset breeding density of ecological fish, it ensures good fish-vegetable symbiosis and effectively removes the nitrogen and phosphorus content in domestic sewage to achieve an ecological symbiotic balance.

[0032] The domestic sewage treated by this sewage treatment and cascade resource utilization system is mainly rural domestic sewage. The characteristics of rural domestic sewage are low concentration and small discharge volume. The peak discharge period of each day is usually three periods, namely the time period of three meals a day. In this way, the collected sewage does not need to be stored in a larger temporary storage pool, but can be directly introduced into the pretreatment unit. After entering the biological treatment unit through the pretreatment unit, the domestic sewage introduced into this sewage treatment and cascade resource utilization system during the activation stage can stay in the corresponding tank body in the biological treatment unit for a long period of time, generally about 7-14 days. After each tank body of the biological treatment unit can achieve overflow for continuous flow, the entire system is considered to be officially in stable operation.

[0033] In actual application, the COD concentration in the wastewater discharged from the aerobic pool 2 needs to be controlled to be 60-70 mg / L, the total nitrogen concentration to be 20-30 mg / L, and the total phosphorus concentration to be 2-3 mg / L; and the preset planting density of the economic crops in the breeding pool 4 is: the crop planting spacing is 10-15 cm, the row spacing is 15-20 cm, and 40-80 plants can be cultivated per square meter; the preset breeding density of the ecological fish in the breeding pool 4 is 680 per mu. -1000, among which, specifically 400-600 grass carp, 200-300 silver carp and 80-100 bighead carp can be stocked per mu. This stocking density takes into account factors such as the growth space of fish, feed resources and water purification capacity. Silver carp and bighead carp can utilize plankton and fish feces in sewage, and grass carp mainly eats the roots and rhizomes of economic crops. They cooperate with each other and can effectively utilize the resources in the breeding pond 4 to carry out good symbiosis.

[0034] This sewage treatment and cascade resource utilization system is designed to make fuller use of resources. Figure 1 and Figure 6 As shown, according to another embodiment of the present invention, the sewage treatment and cascade resource utilization system further includes a cascade utilization unit, and the cascade utilization unit includes breeding hydroponic areas 5 arranged in sequence and connected by utilizing height differences, wherein the breeding hydroponic area 5 located at the highest point is connected to the breeding pond 4.

[0035] For rural areas in hilly areas, most of them are mountainous with a certain height difference; multiple breeding hydroponic areas 5 are arranged by rationally utilizing the terrain; the water discharged from the breeding pond 4 is introduced into the breeding hydroponic area 5 connected to it, and then under the action of gravity, the water is introduced into the remaining breeding hydroponic areas 5 in turn, and fish can be raised and crops can be cultivated in the breeding hydroponic area 5.

[0036] When fish are raised in the hydroponic area 5, the water depth in the hydroponic area 5 can be controlled to be 1.0-1.5 meters, and the excess water can be introduced into the farmland through a pipeline for irrigation, etc. Among them, grass carp, silver carp, etc. can be raised in the hydroponic area 5, and the stocking density is 200-500 per mu.

[0037] When cultivating crops in the hydroponic area 5, the crops are adjusted according to the season. In spring and summer: in the first-level hydroponic area 5, water spinach, tomatoes and other crops with high nitrogen and phosphorus requirements are hydroponic, and the first-level treatment is relatively less to meet the nitrogen and phosphorus requirements of water spinach, tomatoes and other crops; the second-level hydroponic area 5 is hydroponic for crops with relatively low nitrogen and phosphorus requirements, such as Chinese cabbage and lettuce; the third-level hydroponic area 5 can also hydroponic the same crops as the second-level hydroponic area 5. In autumn and winter: the first-level hydroponic area 5, the second-level hydroponic area 5 and the third-level hydroponic area 5 can all hydroponic crops such as lettuce.

[0038] Furthermore, the feeding hydroponic area 5 is provided with a liquid level monitoring device and is also provided with a first water quality monitor, a first nitrate nitrogen sensor and a first dissolved oxygen sensor. The liquid level monitoring device may be a liquid level meter to monitor the liquid level in the feeding hydroponic area 5, a first water quality monitor to monitor the water quality, a first nitrate nitrogen sensor to monitor the nitrate nitrogen, and a first dissolved oxygen sensor to monitor the dissolved oxygen concentration. The monitored results are analyzed, and then the return flow of the sewage circulation part 3 is adjusted in real time to ensure that the fish cultured or the crops cultivated in the cascade utilization unit can grow well.

[0039] like Figure 2 , Figure 3 as well as Figure 7 As shown, according to another embodiment of the present invention, a sewage treatment and cascade resource utilization system, wherein the pretreatment unit includes a grille well 6, the grille well 6 is located at the front side of the anoxic tank 1 and has a filter chamber and a garbage collection chamber 61 located below the filter chamber, the filter chamber is divided into a front filter chamber 62 and a rear filter chamber 63 by a grille filter 64, the front filter chamber 62 is connected to a sewage inlet pipe, the rear filter chamber 63 is connected to the anoxic tank 1, the front filter chamber 62 and the garbage collection chamber 61 are connected through a slag guide port 65 with a preset height, and the floating objects trapped in the front filter chamber 62 are transferred to the slag guide port 65 under buoyancy or a transport tool.

[0040] Specifically:

[0041] The sewage inlet pipe guides domestic sewage into the front filter chamber 62, and intercepts large particles of impurities in the domestic sewage through the grille filter 64. The large particles of impurities in the domestic sewage are basically some floating objects. The outlet of the sewage inlet pipe is specifically located on the side wall of the bottom side of the front filter chamber 62. The sewage introduced into the front filter chamber 62 by the sewage inlet pipe has a certain upward push force on the large particles of impurities intercepted in the front filter chamber 62, so as to guide the large particles of impurities from the slag guide port 65 into the garbage collection chamber 61 for collection; the domestic sewage passes through the grille filter 64 into the rear filter chamber 63, and then enters the biological treatment unit for biological treatment.

[0042] The large particles of impurities trapped in the front filtering chamber 62 can be introduced into the garbage collection chamber 61 from the slag guide port 65 for collection by a transport tool; the transport tool can be a robot or the like.

[0043] Wherein, the sewage inlet pipe is provided with a liquid inlet pump, and the aerobic pool 2 and the anoxic pool 1 are both provided with a second water quality monitor, a second nitrate nitrogen sensor and a second dissolved oxygen sensor.

[0044] Here, the liquid inlet pump provides power for the domestic sewage to enter the grid well 6 and can also adjust the inlet flow of domestic sewage according to demand; the second water quality monitor monitors the water quality, the second nitrate nitrogen sensor monitors the nitrate nitrogen, and the second dissolved oxygen sensor monitors the dissolved oxygen concentration. According to the monitored nitrate nitrogen and dissolved oxygen concentrations, the return flow of the sewage circulation part 3 is adjusted in real time. When the nitrate nitrogen concentration in the anoxic zone is too low, the return flow of the sewage circulation part 3 is appropriately increased; when the dissolved oxygen concentration is too high, the return flow of the sewage circulation part 3 is reduced to maintain a good denitrification environment in the anoxic zone.

[0045] like Figure 2 and Figure 3 As shown, according to another embodiment of the present invention, the sewage treatment and cascade resource utilization system, wherein the biological treatment unit further includes an anaerobic tank 7 located in front of the anoxic tank 1 and connected thereto. That is, the anaerobic tank 7 is connected between the post-filtration chamber 63 and the anoxic tank 1, and the domestic sewage derived from the post-filtration chamber 63 enters the anaerobic tank 7 for treatment, and then the domestic sewage enters the anoxic tank 1 and the aerobic tank 2 in turn in an overflow manner for biological treatment, and uses microorganisms to decompose organic matter.

[0046] The biological treatment unit further comprises a clean water tank 8 located at the rear side of the aerobic tank 2 and connected thereto, and the clean water tank 8 is also connected to the breeding tank 4. The domestic sewage treated in the aerobic tank 2 enters the clean water tank 8 for storage and sedimentation, and then the domestic sewage is introduced into the breeding tank 4 for use.

[0047] In this embodiment, biological fillers are provided in both the aerobic pool 2 and the anoxic pool 1 , and a certain reserved distance is provided between the biological fillers and the bottom and top of the aerobic pool 2 or the anoxic pool 1 .

[0048] Among them, the biological filler is used as a carrier for microbial biofilm. The type of biological filler can be selected very flexibly, as long as it is conducive to the attachment of microorganisms and the formation of a stable biofilm. Preferably, it can be a soft filler (processed to simulate the shape of natural aquatic plants), a modified soft filler (using a spun fiber rope to connect plastic discs with fiber filaments evenly distributed to form a unit fiber bundle of a certain length) and a combined filler (combining the advantages of soft fillers and semi-soft fillers), such as a biological rope filler. Taking the biological rope filler as an example, it is suspended in the lower middle area of ​​the aerobic pool 2 and the anoxic pool 1, and it has a certain distance from the pool bottom and the overflow port; its distance from the pool bottom ensures that the biological rope filler has a good drape, and the biofilm grown on it is relatively stable, thereby ensuring the effect of microbial degradation; in the aerobic pool 2, its distance from the overflow port ensures the normal operation of the sewage circulation part 3.

[0049] like Figure 3 and Figure 4As shown, according to another embodiment of the present invention, a sewage treatment and cascade resource utilization system, wherein the sewage circulation part 3 includes an annular cofferdam 31, a fountain aerator 32 and a return weir 33, the annular cofferdam 31 is circumferentially distributed on the top edge of the aerobic tank 2; the fountain aerator 32 is arranged in the aerobic tank 2, and is used to spray the sewage in the aerobic tank 2 into the annular cofferdam 31; the return weir 33 is arranged on the top edge of the anoxic tank 1 and is connected to the annular cofferdam 31, and the return weir 33 is also connected to the anoxic tank 1.

[0050] In this embodiment, the fountain aerator 32 is operated to perform aeration, and at the same time, the domestic sewage in the aerobic pool 2 is lifted to the surroundings, and part of the domestic sewage is received by the annular cofferdam 31 for collection. The domestic sewage collected in the annular cofferdam 31 is introduced into the return weir 33 through a conducting hole connected to the return weir 33, and the domestic sewage in the return weir 33 is guided back to the anoxic pool 1 through a return liquid hole opened at the bottom of the return weir 33 and connected to the anoxic pool 1, thereby forming a return liquid circulation between the aerobic pool 2 and the anoxic pool 1, so as to facilitate adjusting the nitrogen and phosphorus content in the effluent of the aerobic pool 2 to the preset content value according to demand.

[0051] Specifically, after aeration in the aerobic pool 2, the oxygen in the water is relatively sufficient. The aerobic bacteria decompose the large particles of pollutants in the domestic sewage into small particles of organic debris, and multiply and attach to the biological filler in large quantities to form a stable biofilm. Among them, the nitrifying bacteria convert the ammoniation products into nitrates, so the water in the aerobic pool 2 can be called nitrification liquid; at the same time, part of the nitrification liquid is returned to the anoxic pool 1 through aeration, bringing a small amount of oxygen to the anoxic pool 1, and the returned nitrification liquid can be decomposed by denitrifying bacteria (facultative anaerobic bacteria) into nitrogen gas to escape, so as to achieve the effect of nitrogen removal; the return flow also brings about the flow of water. Since the domestic sewage stays in each pool for a long time, if the water does not flow for a long time, it is inevitable to turn black and smelly; the oxygen in the returned water is relatively sufficient, and it flows directly to the bottom of the pool and then overflows from the top of the pool. This process can not only make the dissolved oxygen in the water more uniform, but also cause a certain disturbance to the water, so that the organic matter in the sewage can contact and act more fully with the biofilm.

[0052] Among them, a buoy is provided in the aerobic pool 2, and the fountain aerator 32 is arranged on the buoy. The buoy is used as an installation carrier of the fountain aerator 32. And a limiting cylinder 9 is fixedly arranged in the aerobic pool 2, and the buoy is arranged on the limiting cylinder 9. The setting of the limiting cylinder 9 can ensure the working stability of the fountain aerator 32 and the stability of the flow rate of the nitrification reflux liquid. The cylinder wall of the limiting cylinder 9 is in a grid shape, which also ensures that it will not block the water splash of the fountain aerator 32, and ensures that the annular cofferdam 31 can receive a large amount of water splash.

[0053] The number of the fountain aerators 32 can be designed according to demand. In the present embodiment, there are two fountain aerators 32. The two fountain aerators 32 can ensure sufficient aeration to ensure the amount of dissolved oxygen in the water body, and can ensure that the annular cofferdam 31 can receive more water splashes, thereby reducing the aeration amount of a single fountain aerator 32.

[0054] like Figure 5 As shown, according to another embodiment of the present invention, a sewage treatment and cascade resource utilization system is described, wherein a grid support assembly 10 is provided in the breeding pond 4, and the grid support assembly 10 includes a lower grid plate 101 and an upper grid plate 102, wherein the lower grid plate 101 is provided in the breeding pond 4 and is located below a preset maximum liquid level in the breeding pond 4, and the roots and stems of economic crops pass through the mesh holes of the lower grid plate 101 and are placed in the sewage in the breeding pond 4; the upper grid plate 102 is provided at the pool mouth of the breeding pond 4 and is located above the lower grid plate 101, and the upper grid plate 102 is located above the preset maximum liquid level, and a constrained space is formed between the lower grid plate 101 and the upper grid plate 102, and the roots and stems of economic crops pass through the mesh holes of the upper grid plate 102.

[0055] In this embodiment, the lower grid plate 101 and the upper grid plate 102 are both equipped with a support platform formed on the inner wall of the breeding pond 4 to provide stable support therefor, and the lower grid plate 101 and the upper grid plate 102 can ensure that cash crops can be stably cultivated in the breeding pond 4, and the roots and stems of the cash crops can always be placed in the domestic sewage in the breeding pond 4 to absorb nitrogen and phosphorus in the domestic sewage in the breeding pond 4, ensuring that the growth of the cash crops can obtain sufficient nutrition, and at the same time can be effectively separated from the fish.

[0056] The sewage treatment and cascade resource utilization system is specifically used as follows:

[0057] The sewage inlet pipe guides the domestic sewage into the front filter chamber 62. After the large particles of impurities are intercepted by the grid filter 64, the domestic sewage passes through the grid filter 64 and enters the rear filter chamber 63 to complete the pretreatment.

[0058] The domestic sewage entering the post-filtration chamber 63 is sequentially sent to the anaerobic tank 7, the anoxic tank 1 and the aerobic tank 2 to decompose organic matter, and is aerated and refluxed by the fountain aerator 32 to adjust the nitrogen and phosphorus content in the effluent of the aerobic tank 2 to a preset content value, and the domestic sewage discharged from the aerobic tank 2 enters the clean water tank 8 for storage;

[0059] The domestic sewage in the rear clear water tank 8 enters the breeding pond 4, in which economic crops and ecological fish are cultivated according to the design for symbiosis, thereby reducing the nitrogen and phosphorus content in the domestic sewage;

[0060] The domestic sewage treated in the culture pond 4 is introduced into the multi-stage aquaculture area 5 for use, so that water resources can be fully utilized.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A sewage treatment and cascade resource utilization system, characterized in that: including an aquaponics unit connected to a biological treatment unit; The biological treatment unit includes an anoxic tank and an aerobic tank connected thereto, a sewage circulation part is arranged between the aerobic tank and the anoxic tank, and the sewage circulation part is used to adjust the nitrogen and phosphorus content in the effluent of the aerobic tank to a preset content value; The fish-vegetable symbiotic unit includes a breeding pond connected to an aerobic pond, wherein economic crops produced by using nitrogen- and phosphorus-rich wastewater treated in the aerobic pond to provide nutrition are cultivated on the top of the breeding pond, and the economic crops are cultivated according to a preset cultivation density, and multiple species of mixed ecological fish are cultivated at the bottom of the breeding pond, and the multiple species of mixed ecological fish are cultivated according to a preset cultivation density and include fish that feed on the roots of economic crops and fish that feed on fish feces.

2. A sewage treatment and cascade resource utilization system according to claim 1, characterized in that: It also includes a step utilization unit, which includes breeding and hydroponic areas that are arranged and connected in sequence using height differences, wherein the breeding and hydroponic area located at the highest point is connected to the breeding pond.

3. A sewage treatment and cascade resource utilization system according to claim 2, characterized in that: The breeding and hydroponic areas are all provided with liquid level monitoring equipment and are also provided with a first water quality monitor, a first nitrate nitrogen sensor and a first dissolved oxygen sensor.

4. A sewage treatment and cascade resource utilization system according to any one of claims 1 to 3, characterized in that: The sewage circulation unit comprises: An annular cofferdam, which is distributed circumferentially at the top edge of the aerobic tank; A fountain aerator, which is arranged in the aerobic pool and is used to spray the sewage in the aerobic pool into the annular cofferdam; A reflux weir is arranged at the top edge of the anoxic pool and is connected to the annular cofferdam. The reflux weir is also connected to the inside of the anoxic pool.

5. A sewage treatment and cascade resource utilization system according to claim 4, characterized in that: A buoy is arranged in the aerobic pool, and a fountain aerator is arranged on the buoy.

6. A sewage treatment and cascade resource utilization system according to any one of claims 1 to 3, characterized in that: It also includes a pretreatment unit located in front of the biological treatment unit, the pretreatment unit comprising: A grid well, wherein the grid well is located in front of the anoxic pool and has a filter chamber and a garbage collection chamber located below the filter chamber. The filter chamber is divided into a front filter chamber and a rear filter chamber by a grid filter. The front filter chamber is connected to a sewage inlet pipe, and the rear filter chamber is connected to the anoxic pool. The front filter chamber and the garbage collection chamber are connected through a slag guide port with a preset height. Floating objects trapped in the front filter chamber are transferred to the slag guide port under buoyancy or a transport tool.

7. A sewage treatment and cascade resource utilization system according to claim 6, characterized in that: The sewage inlet pipe is provided with a liquid inlet pump, and the aerobic pool and the anoxic pool are both provided with a second water quality monitor, a second nitrate nitrogen sensor and a second dissolved oxygen sensor.

8. A sewage treatment and cascade resource utilization system according to claim 1, characterized in that: A grid support assembly is provided in the breeding pond, and the grid support assembly comprises: A lower grid plate, wherein the lower grid plate is arranged in the culture pond and is located below a preset maximum liquid level in the culture pond, and the roots and stems of the economic crops pass through the meshes of the lower grid plate and are placed in the sewage in the culture pond; An upper grid plate is arranged at the mouth of the breeding pond and above the lower grid plate. The upper grid plate is located above a preset maximum liquid level. A constrained space is formed between the lower grid plate and the upper grid plate. The roots and stems of economic crops pass through the meshes of the upper grid plate.

9. A sewage treatment and cascade resource utilization system according to claim 1, characterized in that: The biological treatment unit also includes an anaerobic tank located in front of the anoxic tank and connected to the anoxic tank.

10. A sewage treatment and cascade resource utilization system according to claim 1, characterized in that: The aerobic pool and the anoxic pool are both provided with biological fillers, and the biological fillers in the aerobic pool or the anoxic pool have a certain reserved distance from the bottom and the top of the pool.

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