CN218879655U - An Ecological Natural Pond-Wetland Composite Purification System - Google Patents

Abstract

The utility model discloses an imitative ecological natural pond-wetland composite purification system, include: the system comprises a pretreatment pond, a ditch-subsurface flow bed alternate wetland ecological purification area, a post-treatment pond and a water taking area which are communicated in sequence; a water inlet area, an ecological purification area and a water outlet area which are sequentially communicated are arranged in the ditch-subsurface flow bed alternate wetland ecological purification area; the ecological purification area presents a natural gradient from the water inlet area to the water outlet area from high to low, and the water flow presents advection and undercurrent alternate flow in the horizontal direction and directly passes through the ecological purification area from the water inlet area to the water outlet area. The utility model discloses when adopting the compound purification mode of "pool-wetland-pool" to handle plain river network micro-polluted water source, utilize the combination of "irrigation canals and ditches-undercurrent formula ecological purification bed" to form degree of depth undercurrent wetland, restrain the excessive reproduction of alga at the wetland, the play water after the processing can be as city water supply stock water source or reserve water source.

Description

An ecological natural pond-wetland composite purification system

Technical Field

The utility model relates to the technical field of micro-polluted water source treatment, in particular to an ecologically simulated natural pond-wetland composite purification system.

Background Art

In recent years, the trend of water pollution and ecological damage in the river network area in southern China has not been effectively curbed, and the deterioration of water source quality has become a problem faced by many water plants in the river network area. The key to ensuring the safety of drinking water quality is water source protection and restoration. The protection of drinking water sources plays a vital role in reducing drinking water treatment costs and improving drinking water quality.

At present, the utility model patent with the authorization announcement number CN1314601C and the name of "Segmented Free Surface Flow Artificial Wetland Treatment Method and System" discloses a non-point source pollution control method and system for purifying eutrophic water in river network areas by using segmented free surface flow artificial wetlands. The design is based on characteristic factors such as plant species, filler type, ecological chain and riverbed, and the existing river channel is transformed into a segmented free surface flow artificial wetland, so that the surface runoff passes through the free surface flow artificial wetland module with different pollutant removal tendencies before flowing into rivers and lakes, and the eutrophication is purified under the combined action of microorganisms-fillers-fillers-aquatic animals. The segmented free surface flow artificial wetland does not require the construction of treatment structures or pipe networks, does not affect the flood discharge function of the original river network area, and at the same time, the water flows through the artificial wetland system by gravity, without power consumption, and is suitable for promotion and application in river network areas around rivers and lakes.

The application publication number is CN102234165A, and it is named "A system for purifying sewage using artificial wetlands and a systematic method for purifying polluted source water of a water plant". This method constructs a large-scale ecological water quality purification wetland system before the water inlet of the water plant, including multiple functional areas such as the pretreatment area, the water level lifting and aeration oxygenation area, the wetland root hole ecological purification area, the deep purification area, and the standard water diversion area. In the wetland root hole ecological purification area, a purification system combining artificial root holes and natural root holes is constructed by artificially constructing wetland root holes. This method processes 200,000 to 240,000 tons of source water from the water plant per day, achieving the effect of improving the main water quality indicators by one level and multiple ecological service functions.

Although the above methods have improved the water quality of polluted water sources to a certain extent, their treatment methods still remain at the traditional wetland plant purification to remove organic pollution, nitrogen, phosphorus and other pollutants, and cannot solve the odor problem caused by excessive algae growth in wetlands; at the same time, the removal of new types of pollution such as antibiotics and halides by wetlands has not been considered.

Utility Model Content

The utility model provides an ecological natural pond-wetland composite purification system, which can not only inhibit the excessive reproduction of algae in the wetland, but also significantly improve the removal effect of new pollution such as antibiotics and halogenated substances.

The specific technical solutions are as follows:

An ecological natural pond-wetland composite purification system, comprising: a pre-treatment pond, a ditch-undercurrent bed alternating wetland ecological purification area, a post-treatment pond and a water intake area, which are connected in sequence; the ditch-undercurrent bed alternating wetland ecological purification area is provided with a water inlet area, an ecological purification area and a water outlet area, which are connected in sequence;

The ecological purification area presents a natural slope from high to low from the water inlet area to the water outlet area, and the water flows in the horizontal direction alternating between horizontal flow and undercurrent, and flows directly from the water inlet area through the ecological purification area to the water outlet area; the ecological purification area is alternately provided with ditches and undercurrent ecological purification beds along the direction of water flow, and the ditches are divided into deep ditches and shallow ditches, and the deep and shallow ditches are alternately arranged; in the direction perpendicular to the water flow direction, both ends of the ditches and the undercurrent ecological purification beds are provided with dams to limit the flow in and out of water.

The utility model not only adopts the composite purification mode of "pond-wetland-pond" to treat the slightly polluted water source of the plain river network, but also utilizes the combination of "ditch-undercurrent bed" to form a deep undercurrent wetland, which can not only inhibit the excessive reproduction of algae in the wetland, but also significantly improve the removal effect of new pollution such as antibiotics and halogenated substances.

Furthermore, a water level raising pump is provided upstream of the pre-treatment pond, and the slightly polluted water from natural river and lake sources enters the pre-treatment pond through the water level raising pump. The pre-treatment pond is divided into a front pond deep pool area and a front pond shallow beach area, and the transition area between the front pond deep pool area and the front pond shallow beach area is set as an aeration and oxygenation area for artificially increasing dissolved oxygen.

Furthermore, the pre-treatment pond is divided into a front pond deep pool area and a front pond shallow beach area, the front pond deep pool area is connected to the water level lifting pump, and the front pond shallow beach area is connected to the water inlet area of the ditch-undercurrent bed alternating wetland ecological purification area.

Furthermore, the transition area between the Qiantang deep pool area and the Qiantang shallow beach area is set as an aeration and oxygenation area for artificially increasing dissolved oxygen.

Furthermore, the shallow area of Qiantang is lined with blocks of stone and gravel, a number of limiting wooden stakes for fixing the blocks of stone and gravel are inserted into the underwater soil, and floating plants are planted on the water surface; limestone as a reinforced base is placed on the underwater gentle slope outside the shallow area of Qiantang; the slow-released calcium ions of the limestone help to flocculate the colloid particles in the water and precipitate phosphates, thereby reducing turbidity and removing phosphorus, and buffering and adjusting the pH value of the water body to inhibit the growth of algae.

In order to achieve better water contact and exchange effects and prevent stones from rolling down, it is preferred to fill limestone into gabion boxes and place the gabion boxes on the underwater gentle slope outside the shallow area of the front pond. The thickness of the gabion boxes is 20 to 30 cm, and the particle size of the limestone inside is 6 to 8 cm.

Preferably, a pre-treatment river channel or pre-treatment channel with a length of 100 to 1000 m is provided upstream of the pre-treatment pond; the river channel or channel can reduce suspended particles and various pollutants carried in the slightly polluted water source.

Furthermore, the pre-treatment pond may be composed of a plurality of ponds.

Furthermore, the water outlet area is provided with a water outlet connected to a shallow ditch at the end of the water flow in the ecological purification area.

Furthermore, the submerged flow ecological purification bed is provided with an aquatic plant planting area, a water flow area and a ventilation area from top to bottom; the aquatic plant planting area is filled with a permeable hard granular cultivation matrix, the water flow area is filled with a large granular purification bed carrier for water flow to pass through, and the ventilation area is provided with a number of ventilation pipes for aeration.

Furthermore, the aquatic plant planting area is filled with a permeable hard granular cultivation substrate, the water flow area is filled with a large granular purification bed carrier for water flow to pass through, and the ventilation area is provided with a plurality of ventilation pipes for aeration.

Furthermore, a pipe network formed by a number of crisscrossed perforated small tubes is suspended on the water surface of the ditch; both ends of the perforated small tubes are sealed, and the tubes are filled with submerged plant seeds and a substrate for seed growth.

Furthermore, in the first deep ditch downstream of the pre-treatment pond, an ultrasonic generating tube is provided directly below the pipe network, and the ultrasonic generating tube is suspended below the pipe network through a corrosion-resistant rope.

Furthermore, the distance from the bottom of the ditch to the wetland surface is taken as the ditch depth, the depth ratio of the deep ditch to the shallow ditch is 1.0-10:1, and the width ratio is 0.5-5.0:1; slope protection is provided in the ecological purification area to protect the deep and shallow ditches.

The water area of shallow ditches accounts for 5% to 25% of the ecological purification area, the water area of deep ditches accounts for 15% to 40% of the ecological purification area, and the rest is the area occupied by subsurface ecological purification beds.

The post-treatment pond has a large area, depth and water storage capacity, and can be used to store more purified raw water to meet the needs of subsequent water intake or emergency backup water supply. Further, the post-treatment pond is divided into a back pond deep pool area and a back pond shallow beach area; wherein the back pond deep pool area is connected to the water outlet area, and the back pond shallow beach area is connected to the water intake area. A multi-level pond combination can be used.

In the deep pool area of Houtang, aquatic animals such as snails, clams and fish can be released in appropriate quantities, and the fish released should mainly be filter-feeding fish; submerged plants can be introduced in appropriate quantities in the shallow water area at the edge to strengthen the circulation of water bodies, reduce dead water areas, and prevent algae from hydrating and breaking out. Pebbles or gravel bases can be laid on the slope terraces around the shallow area of Houtang and the communication channels close to the water outlet to further strengthen the purification of water bodies and the stabilization of water quality in the post-treatment pond.

Furthermore, a submerged spur dike group is set up in the Houtang deep pool area and the Houtang shallow beach area; the submerged spur dike group is composed of 3 to 5 or more submerged spur dikes, the dam top length of each submerged spur dike is 10 to 60% of the water surface width in the area, the spur dike cross-sectional area is designed to be 10 to 30% of the water area in the area, the dam top of the spur dike is submerged 10 to 60 cm below the normal water level, and evergreen aquatic trees or aquatic plants are planted on the dam top.

Furthermore, the water depth range of the ecological purification zone is 0.2 to 3.5 m; among them, the elevation of the subsurface ecological purification bed is 0 to 50 cm higher than the normal water level, the water depth of the deep ditch is 1.5 m to 3.5 m, and the water depth of the shallow ditch is 0.3 m to 1.4 m; the aquatic plant planting area in the subsurface ecological purification bed is set at 0 to 50 cm below the surface, the water flow area is set at 55 to 150 cm below the surface, and the ventilation area is set at 155 to 200 cm below the surface.

Furthermore, the water-passing area is composed of a lower gravel area and an upper pebble area; the aquatic plant planting area is filled with a substrate, and aquatic plants with well-developed root systems are planted on the substrate.

Compared with the prior art, the utility model has the following beneficial effects:

The utility model not only adopts the composite purification mode of "pond-wetland-pond" to treat the slightly polluted water source of the plain river network, but also utilizes the combination of "ditch-subsurface flow ecological purification bed" to form a deep subsurface flow wetland to inhibit the excessive reproduction of algae in the wetland. The treated effluent can be used as a standing water source or backup water source for urban water supply, with a DO value of ≥5.0mg/L, chemical oxygen demand ≤20mg/L, ammonia nitrogen ≤4.0mg/L, total phosphorus ≤0.2mg/L, and algae count less than 50 million/liter, and has different degrees of removal effect on antibiotics, halogenated substances and other pollution.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of the structure of an ecological natural pond-wetland composite purification system.

FIG. 2 is a schematic diagram of the main structural view of the ditch-undercurrent bed alternating wetland ecological purification area in the ecological natural pond-wetland composite purification system.

FIG. 3 is a schematic diagram of the overhead structure of the ditch-undercurrent bed alternating wetland ecological purification area in the ecological natural pond-wetland composite purification system.

FIG. 4 is an enlarged view of point A in FIG. 2 .

FIG. 5 is a schematic diagram of the main structural view of the pre-treatment pond in the ecological natural pond-wetland composite purification system.

FIG. 6 is a schematic diagram of the main structural view of the post-treatment pond in the ecological natural pond-wetland composite purification system.

In the figure, 1 is a natural river or lake water source, 2 is a water level lifting pump, 3 is a pre-treatment pond, 4 is a ditch-undercurrent bed alternating wetland ecological purification area, 5 is a post-treatment pond, 6 is a water intake area, 31 is a front pond deep pool area, 32 is a front pond shallow beach area, 321 is a block stone, 322 is gravel, 323 is a limiting wooden pile, 324 is a floating plant, 325 is a gabion cage, 33 is an aeration and oxygenation area, 34 is a pre-treatment river channel, 41 is an inlet area, 42 is an ecological purification area, 43 is an outlet area, 421 is a ditch, 422 is a subsurface ecological purification bed, 4211 is a deep Ditch, 4212 is a shallow ditch, 4221 is an aquatic plant planting area, 4222 is a water passing area, 4223 is a ventilation area, 423 is a dam, 431 is an outlet, 4222-1 is a lower gravel area, 4222-2 is an upper pebble area, 4221-1 is a substrate, 4221-2 is aquatic plants, 4213 is a small tube with holes, 4214 is a pipe network, 4215 is submerged plant seeds and a substrate for seed growth, 4216 is an ultrasonic generating tube, 51 is a deep pool area of Houtang, 52 is a shallow beach area of Houtang, and 53 is a submerged spur dike.

DETAILED DESCRIPTION

The present invention will be further described below in conjunction with specific embodiments. The following are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto.

The determination methods of various indicators involved in the following application examples are as follows: dissolved oxygen content (DO) uses a portable dissolved oxygen meter, chemical oxygen demand (COD _Cr ) uses potassium dichromate method, permanganate index (COD _Mn ) uses acid elution, ammonia nitrogen (NH4+-N) uses sodium reagent photometry, total phosphorus (TP) uses ammonium molybdate spectrophotometry, and algae counts use plankton quantitative method.

Example 1 Ecological natural pond-wetland composite purification system

As shown in Figures 1 to 4, an ecological natural pond-wetland composite purification system is shown, which includes a natural river and lake water source 1 connected in sequence, a water level lifting pump 2, a pre-treatment pond 3, a ditch-undercurrent bed alternating wetland ecological purification area 4, a post-treatment pond 5 and a water intake area 6.

Among them, the pre-treatment pond 3 is equipped with an aeration and oxygenation zone. According to the spatial distribution of the wetland and the changes in the water quality process, the aeration and oxygenation zone can be set up in the parts where the dissolved oxygen is low and aeration is required. A gabion contact filtration system is set up on the platform of the aeration and oxygenation zone to form a gabion dam, which can achieve rapid oxygenation, slow down the water flow, reduce turbidity, remove phosphorus and ammonia nitrogen, and weaken other pollution factors through adsorption and replacement. The upper end of the gabion dam is usually exposed 20 to 50 cm above the water surface and can be arranged in a multi-layer and multi-row layout. The gabion monomer is covered with a gabion mesh, and the gabion mesh is filled with common stones such as gravel, zeolite, calcite, volcanic stone, etc. The stone particle size range is 5 to 10 cm.

The water inlet of the water level raising pump 2 is connected to the natural river or lake water source 1, and the water outlet is connected to the pre-treatment pond 3, so that the water level of the pre-treatment pond 3 can be raised. After aeration and oxygenation, the DO value of the effluent of the pre-treatment pond 3 is ≥5.0mg/L, which can further improve the self-purification capacity of the water body.

The pre-treatment pond 3 is divided into the front pond deep pool area 31 and the front pond shallow area 32. The transition area between the front pond deep pool area 31 and the front pond shallow area 32 is the aeration and oxygenation area 33. The front pond deep pool area 31 is connected to the water level lifting pump 2, and the front pond shallow area 32 is connected to the water inlet area 41 of the ditch-undercurrent bed alternating wetland ecological purification area 4. The front pond shallow area 32 has blocks 321 and gravel 322 in the battlements, and a number of limiting wooden stakes 323 for fixing the blocks 321 and gravel 322 are inserted into the underwater soil, and floating plants 324 are planted on the water surface; limestone 324 for strengthening the base is placed on the underwater gentle slope outside the front pond shallow area 32; the calcium ions slowly released by the limestone help the flocculation of colloid particles in the water and precipitate phosphates, thereby reducing turbidity and removing phosphorus, and buffering and adjusting the pH value of the water body to inhibit the growth of algae. In order to achieve better water quality contact exchange effect and prevent stones from rolling down, limestone is filled in the gabion box 325, and the gabion box 325 is placed on the underwater gentle slope outside the front pond shoal area 32. The thickness of the gabion box is 20-30cm, and the particle size of the limestone inside is 6-8cm. A pre-treatment river channel 33 with a length of 100-1000m is set upstream of the pre-treatment pond 3; the pre-treatment river channel 33 can reduce suspended particles and various pollutants in the slightly polluted water source.

The pre-treatment pond 3 may be composed of a plurality of ponds; for example, two pre-treatment ponds connected in sequence.

The ditch-undercurrent bed alternating wetland ecological purification area 4 is composed of an inlet area 41, an ecological purification area 42 and an outlet area 43 which are connected in sequence. From the inlet area 41 to the outlet area 43, a natural slope is presented from high to low. The water flows in the horizontal direction like an undercurrent bed and directly passes through the ecological purification area 42 from the inlet area 41 to the outlet area 43. The ecological purification area 42 is alternately provided with ditches 421 and undercurrent ecological purification beds 422 along the water flow direction. The ditch 421 is divided into a deep ditch 4211 and a shallow ditch 4212, and the deep and shallow ditches are alternately provided. The chemical bed 422 is provided with an aquatic plant planting area 4221, a water passing area 4222 and a ventilation area 4223 from top to bottom; the water passing area 4222 is filled with purification bed carriers such as large-grained gravel and pebbles for water to flow through; a plurality of ventilation pipes for aeration are provided in the ventilation area 4223; in a direction perpendicular to the water flow direction, dams 423 are provided at both ends of the ditch 421 and the submerged flow ecological purification bed 422 to limit the inflow and outflow of water; the water outlet area 43 is provided with an outlet 431 connected to the shallow ditch 4212 at the end of the water flow in the ecological purification area 42. The water-passing area 4222 is composed of a lower gravel area 4222-1 and an upper pebble area 4222-2; the aquatic plant planting area 4221 is filled with a matrix 4221-1 composed of permeable volcanic rocks, melon seed slices, ceramsite and other hard particles, and aquatic plants 4221-2 with well-developed root systems are planted on the matrix 4221-1.

A pipe network 4214 formed by a number of crisscrossed perforated small tubes 4213 is suspended on the water surface of the ditch 421; both ends of the perforated small tubes are sealed, and the tubes are filled with submerged plant seeds and a matrix 4215 for seed growth. An ultrasonic generator tube 4216 is provided directly below the pipe network 4214 in the first group of deep ditches in the ecological purification area, and the ultrasonic generator tube 4216 is suspended below the pipe network 4214 by a corrosion-resistant rope. The distance from the bottom of the ditch to the surface of the wetland is taken as the ditch depth. The depth ratio of the deep ditch to the shallow ditch is 2 to 10:1, and the width ratio is 1.5 to 5.0:1; slope protection is provided in the ecological purification area to protect the deep and shallow ditches.

The water area of shallow ditches accounts for 5% to 25% of the ecological purification area, the water area of deep ditches accounts for 15% to 40% of the ecological purification area, and the rest is the area occupied by the subsurface ecological purification bed. The water depth of the ditch-subsurface bed alternating wetland ecological purification area ranges from 0.2 to 3.5m; among them, the elevation of the subsurface ecological purification bed is 0 to 50cm higher than the normal water level, the water depth of the deep ditch ranges from 1.5m to 3.5m, and the water depth of the shallow ditch ranges from 0.3m to 1.4m; the aquatic plant planting area in the subsurface ecological purification bed is set at 0 to 50cm below the surface, the water passing area is set at 55 to 150cm below the surface, and the ventilation area is set at 155 to 200cm below the surface.

The post-treatment pond 5 is divided into the Houtang deep pool area 51 and the Houtang shallow area 52; wherein, the Houtang deep pool area 51 is connected to the outlet area 43, and the Houtang shallow area 52 is connected to the water intake area 6. A multi-level pond combination can be adopted. The post-treatment pond has a large area, depth and water storage capacity, and can be used to store more purified raw water to meet the needs of subsequent water intake or emergency backup water supply. Aquatic animals, such as snails, clams, and fish, can be appropriately and appropriately released in the Houtang shallow area, and the fish released should be mainly filter-feeding fish; submerged plants can be introduced in appropriate amounts in the marginal shallow water areas to strengthen the circulation of water bodies, reduce dead water areas, and prevent and control algae hydration outbreaks. Pebbles or gravel bases can be laid on the slope terraces around the Houtang shallow area and the communication channels close to the outlet to further enhance the purification of the water body and the stabilization of the water quality by the post-treatment pond. The Houtang deep pool area is connected to the outlet area, and the Houtang shallow area is connected to the water intake area

Submerged spur dikes are set up in the Houtang deep pool area 51 and the Houtang shallow beach area 52; the submerged spur dike group consists of 3 to 5 submerged spur dikes 53, the crest length of each submerged spur dike is 10 to 60% of the water surface width in the area, the cross-sectional area of the spur dike is designed to be 10 to 30% of the water area in the area, the crest of the spur dike is submerged 10 to 60 cm below the normal water level, and aquatic plants are planted on the crest.

Application Example 1

The raw water from the plain river network in the Taihu Lake Basin was taken as the research object. The water quality of the water source in this area is DO 3.0-7.0 mg/L, COD 10.0-25.0 mg/L, ammonia nitrogen 0.05-1.53 mg/L, and total phosphorus 0.11-0.26 mg/L. An ecological natural pond-wetland composite purification system was set up in this area, and the following methods were used to treat slightly polluted water sources.

Among them, a pre-treatment pond is set at the end of the water intake outlet, a ditch-undercurrent bed alternating wetland ecological purification area is set at the end of the pre-treatment pond, a post-treatment pond is set at the end of the ecological purification area, and a water intake area is set at the outlet of the post-treatment pond.

The specific method is:

(1) The slightly polluted water source enters the pretreatment pond through the water level lifting pump, and then after being oxygenated in the aeration and oxygenation area of the pretreatment pond, the DO value is controlled to be ≥5.0 mg/L and the SS value is controlled to be ≤10.0 mg/L, thus completing the pretreatment;

(2) The water source after the pre-treatment in step (1) flows by gravity into the ditch-undercurrent ecological purification bed area, which is a wetland ecological purification area where ditches and purification beds are alternately arranged, for intermediate treatment;

(3) The water source treated in step (2) enters the post-treatment pond, controls the DO value to be ≥5.0 mg/L, and the algae count to be less than 50 million/L. After post-treatment, the effluent flows into the water intake area to obtain a purified water source.

Results: After about 4 to 9 days of treatment, the effluent water quality indicators reached the Class II water quality indicators of the "Surface Water Environmental Quality Standard" (GB3838-2002), and the growth and reproduction of algae were inhibited.

Table 1-1 Influent water quality of application example 1

Table 1-2 Water quality of effluent from application example 1

。

.

Claims (10)

1. An ecological natural pond-wetland composite purification system, characterized by comprising: a pre-treatment pond, a ditch-undercurrent bed alternating wetland ecological purification area, a post-treatment pond and a water intake area which are connected in sequence; the ditch-undercurrent bed alternating wetland ecological purification area is provided with a water inlet area, an ecological purification area and a water outlet area which are connected in sequence; The ecological purification area presents a natural slope from high to low from the water inlet area to the water outlet area, and the water flows in the horizontal direction alternating between horizontal flow and undercurrent, and flows directly from the water inlet area through the ecological purification area to the water outlet area; the ecological purification area is alternately provided with ditches and undercurrent ecological purification beds along the direction of water flow, and the ditches are divided into deep ditches and shallow ditches, and the deep and shallow ditches are alternately arranged; in the direction perpendicular to the water flow direction, both ends of the ditches and the undercurrent ecological purification beds are provided with dams to limit the flow in and out of water. 2. The ecological natural pond-wetland composite purification system as described in claim 1 is characterized in that the pre-treatment pond is divided into a front pond deep pool area and a front pond shallow beach area, and the transition area between the front pond deep pool area and the front pond shallow beach area is set as an aeration and oxygenation area for artificially increasing dissolved oxygen. 3. The ecological natural pond-wetland composite purification system as described in claim 2 is characterized in that the deep pool area of the front pond is connected to a water level lifting pump, and the shallow area of the front pond is connected to the water inlet area of the ditch-undercurrent bed alternating wetland ecological purification area; the shallow area of the front pond is lined with blocks of stone and gravel, a number of limiting wooden piles for fixing the blocks of stone and gravel are inserted into the underwater soil, and floating plants are planted on the water surface; limestone for strengthening the base is placed on the underwater gentle slope around the shallow area of the front pond. 4. The ecological natural pond-wetland composite purification system as described in claim 3 is characterized in that the limestone is filled in a gabion box, and the gabion box is placed on the underwater gentle slope outside the shallow area of the front pond, the thickness of the gabion box is 20 to 30 cm, and the particle size of the limestone inside is 6 to 8 cm. 5. The ecological natural pond-wetland composite purification system as described in claim 1 is characterized in that the submerged flow ecological purification bed is provided with an aquatic plant planting area, a water flow area and a ventilation area from top to bottom; the aquatic plant planting area is filled with a permeable hard granular cultivation matrix, and the water flow area is filled with a large granular purification bed carrier for water flow to pass through; the ventilation area is provided with a plurality of ventilation pipes for aeration. 6. The ecological natural pond-wetland composite purification system as described in claim 1 is characterized in that a pipe network formed by a number of criss-crossing perforated small tubes is suspended on the water surface of the ditch; both ends of the perforated small tubes are sealed, and the tubes are filled with submerged plant seeds and a matrix for seed growth; in the first deep ditch downstream of the pre-treatment pond, an ultrasonic generating tube is provided directly below the pipe network, and the ultrasonic generating tube is suspended below the pipe network by a corrosion-resistant rope. 7. The ecological natural pond-wetland composite purification system as described in claim 1 is characterized in that the post-treatment pond is divided into a deep pond area and a shallow beach area; wherein the deep pond area is connected to the outlet area, and the shallow beach area is connected to the intake area; aquatic animals are placed in the deep pond area. 8. The ecological natural pond-wetland composite purification system as claimed in claim 7 is characterized in that a submerged spur dike group is set in the deep pool area and the shallow beach area of the back pond; the submerged spur dike group is composed of 3 to 5 submerged spur dikes, the dam top length of each submerged spur dike is 10 to 60% of the water surface width in the area, the spur dike cross-sectional area is 10 to 30% of the water area in the area, the dam top is submerged 10 to 60 cm below the normal water level, and aquatic plants are planted on the dam top. 9. The ecological natural pond-wetland composite purification system as described in claim 1 is characterized in that the water depth range of the ecological purification zone is 0.2 to 3.5 m; wherein the elevation of the submerged flow ecological purification bed is 0 to 50 cm higher than the normal water level, the water depth range of the deep ditch is 1.5 m to 3.5 m, and the water depth range of the shallow ditch is 0.3 m to 1.4 m; the aquatic plant planting area in the submerged flow ecological purification bed is set at 0 to 50 cm below the surface, the water flow area is set at 55 to 150 cm below the surface, and the ventilation area is set at 155 to 200 cm below the surface. 10. The ecological natural pond-wetland composite purification system as described in claim 1 is characterized in that, in the ecological purification area, the shallow ditch water area accounts for 5% to 25% of the ecological purification area, the deep ditch water area accounts for 15% to 40% of the ecological purification area, and the remaining proportion is the area occupied by the subsurface ecological purification bed.

Images