Urban internal lake bypass treatment water quality improving system and application method thereof

Abstract

The invention discloses an urban internal lake bypass treatment water quality improving system and an application method thereof, a lake water pump well is connected with a sedimentation tank through a first valve well, the sedimentation tank is connected with a filter tank through a first overflow wall, and the filter tank is sequentially connected with an aeration tank, a water quality improving tank and a water purifying tank; the water quality improving pool is composed of a plurality of pool bodies, the pool bodies are separated by fourth overflow walls, and the fall between the pool bodies is 0.1-0.3 m. Aiming at the polluted urban internal lake without a stable water replenishing source, the invention realizes the large circulation of the internal lake water body, improves the water power and increases the self-purification capacity of the water body on the premise of not changing the current situation of the urban internal lake and the original ecological system structure, and is suitable for improving the water quality of the urban internal lake under different water quality conditions.

Description

Technical Field

[0001] The present invention belongs to the technical field of surface water treatment, and in particular relates to a water quality improvement system for a bypass treatment of an urban lake and an application method thereof. Background Art

[0002] The increase in urban populations and the expansion of human activities have negatively impacted urban lakes and rivers, causing varying degrees of damage to aquatic ecosystems. Algae are proliferating, water transparency is decreasing, and aquatic plant and animal species are decreasing. Severely polluted lakes and rivers can even become black and smelly, negatively impacting their wetland, tourism, and water storage functions. Eutrophication, caused by nitrogen and phosphorus pollution, has become a prominent pollution problem in urban rivers and lakes in my country. Controlling nitrogen and phosphorus pollution in urban rivers and lakes and reducing eutrophication are urgent and crucial issues in my country's water pollution control efforts.

[0003] Technical measures for urban river and lake management are categorized into in-situ and ex-situ methods, with in-situ management generally adopted, including ecological purification, artificial oxygenation, and active water circulation. For urban lakes without a stable water supply, the hydrodynamics are poor and the self-purification capacity of the water bodies is severely insufficient. The aforementioned water quality improvement technologies are unable to improve the hydrodynamics of urban lakes to restore their self-purification capacity and maintain long-term water quality.

[0004] Chinese patent CN111056644A discloses a small watershed ecological governance water quality improvement treatment system and treatment method. It constructs an ecological conservation composite three-stage process transformation through ecological sedimentation tanks, ecological conservation wetlands and ecological conservation ponds connected in sequence, diverts water from the watershed, and then uses aquatic plants and indigenous microorganisms as the basis to build a complete ecological chain community to achieve deep improvement of water quality. Finally, the water is returned to the river channel in an ecological water replenishment manner to achieve the purpose of improving the water quality of the entire watershed.

[0005] Chinese patent CN116975555A discloses an integrated treatment system and optimization method for urban lake water pollution control technology. First, according to the requirements of local lake blue line protection and water system protection, the near-natural and locally adapted design principles are determined, and the front buffer zone process is selected; then, according to the design parameters of the main wetland process units, the appropriate enhanced treatment area process is selected according to the purification requirements and the influent concentration; then, a grass-type clear water lake is constructed, and the self-purification capacity of the water body is used to further remove pollutants in the lake area; then, the total amount of pollutants and the minimum cost of each indicator are used as the objective function, considering the total amount of pollutants reduction target, the current cost of each indicator, and the upper and lower limits of the total amount of pollutants. The model is optimized and solved using tool software to determine the final optimal allocation plan; it has strong coupling and can quickly determine the process adaptation parameters to achieve the best coordinated treatment state.

[0006] However, current treatment of urban lakes and rivers still relies on constructed wetlands or biochemical wastewater treatment processes. These processes are ineffective for areas with poor water dynamics, a lack of stable water replenishment, and severely insufficient self-purification capacity. Therefore, it is necessary to develop a system that can enhance water dynamics and self-purification capacity to maintain long-term, stable water quality. Summary of the Invention

[0007] In response to the above technical problems, the present invention provides a water quality improvement system for bypass treatment of urban lakes and its application method. For polluted urban lakes without a stable water supply source, without changing the current status of the urban lakes and the original ecosystem structure, the system can achieve a large circulation of the lake water, enhance water dynamics, and increase the self-purification capacity of the water body.

[0008] In order to achieve the above-mentioned purpose, the present invention provides a water quality improvement system for bypass treatment of urban lakes, including a lake water pump well connected to a sedimentation tank via a first valve well, the sedimentation tank is connected to a filter tank via a first overflow wall, the filter tank is connected to an aeration tank, a water quality improvement tank and a water purification tank in sequence; a combined filtration unit and a retaining wall are provided inside the filter tank.

[0009] Preferably, a sewage pump is provided at the bottom of the sedimentation tank and a second cover plate is provided at the top; a first cover plate is provided at the top of the lake water pump well; a sewage steel tank is provided at the bottom of the filter tank and the aeration tank, and a ball valve is provided in the sewage steel tank.

[0010] Preferably, the combined filter unit includes a filter medium and a bracket, and the filter medium includes coconut shell, sponge and activated carbon in order from top to bottom; and a water outlet pipe is provided in the retaining wall.

[0011] Preferably, an aeration rod is provided at the bottom of the aeration tank, and a third overflow wall and a water inlet pipe are provided on one side; the water quality improvement tank is composed of multiple tank bodies, each tank body is separated by a fourth overflow wall, and the height difference between the tank bodies is 0.1-0.3m.

[0012] Further preferably, an ecological filter material module and a plant module are provided at the bottom of the water quality improvement pool, and guardrails and sidewalks are provided around it.

[0013] More preferably, the ecological filter material module includes bagged filter material and a bracket.

[0014] Furthermore, the bagged filter material is made of a polyethylene mesh with an 80-mesh pore size, and is filled with ecological filter material particles mainly composed of silicon-aluminum tetrahedral crystals with a particle size of 2-5 mm; the length, width and height of the bracket are 3.0 m×0.8 m×0.5 m, and the material is a galvanized bracket.

[0015] More preferably, the density of the ecological filter material modules in the water quality improvement pool is 5-7 per m 2The density of plant modules in the water quality improvement pool is 8-10 / m 2 .

[0016] Furthermore, the plants in the plant module are foxtail algae and / or Vallisneria dwarf.

[0017] Furthermore, the ratio of the foxtail algae to the dwarf vallisneria is 1:2.

[0018] Further preferably, the overall capacity of the water quality improvement pool is 1500-2000 tons, and the capacity of each pool body is 500-600 tons.

[0019] Preferably, a coupling device is provided between the water quality improvement pool and the water purification pool, a retaining wall is provided on the other side of the water purification pool, a submersible pump is provided at the bottom, and the submersible pump is connected to the second valve well.

[0020] Further preferably, the coupling device consists of columns and grid plates; and a water intake pump is provided in the second valve well.

[0021] The present invention also provides an application method of a system for improving water quality of an urban lake bypass, comprising the following steps: (1) Based on the water quality, the water in the urban lake is divided into Class IV, Class V and Class V; (2) Introducing water from different types of urban lakes into the water quality improvement system for treatment: Quasi-Class IV water: The water quality improvement system is a low-flow treatment condition with a treatment capacity of 800-1200 tons / day; Class V water: The water quality improvement system is in conventional treatment conditions, with a treatment capacity of 1,700-3,000 tons / day; Poor Class V water: The water quality improvement system is in high-load treatment condition, with a treatment capacity of 5500-6300 tons / day; (3) After the treatment is completed, the water in the water quality improvement system will be discharged to the other side of the urban lake for cyclical treatment.

[0022] Preferably, the COD of the quasi-Class IV water in step (1) is less than 30 mg / L, the ammonia nitrogen content is less than 1.5 mg / L, the total phosphorus content is less than 0.3 mg / L, the permanganate index is less than 10, and the dissolved oxygen is greater than 3 mg / L; the COD of the Class V water is 30-40 mg / L, the ammonia nitrogen content is 1.5-2.0 mg / L, the total phosphorus content is 0.3-0.4 mg / L, the permanganate index is 10-15, and the dissolved oxygen is 2-3 mg / L; the COD of the inferior Class V water is greater than 40 mg / L, the ammonia nitrogen content is greater than 2.0 mg / L, the total phosphorus content is greater than 0.4 mg / L, the permanganate index is greater than 15, and the dissolved oxygen is less than 2 mg / L.

[0023] The beneficial effects of the present invention are as follows: Without changing the existing status and original ecosystem structure of rivers and urban lakes, the present invention uses a combined physical filtration method, including filtration and adsorption media, at the front end to achieve rapid and efficient interception of particulate pollutants such as SS, and adjusts aeration in the aeration tank based on the real-time DO value. In the central water quality improvement tank, ecological filter modules are arranged overhead and submerged plants are planted at the bottom. Adsorbed suspended matter and biofilm are shed and then precipitated, where they are further adsorbed, solidified, and partially absorbed by the aquatic plants. The effluent at the back end is purified through a coupled filtration facility, further improving the water quality of the clear water tank. This invention achieves rapid purification of polluted water in urban lakes, achieves stable water quality, maintains long-term effects, and helps the water restore its self-cleaning function.

[0024] This invention uses a lake water pump well to lift lake water, increasing water dynamics. A height difference is then created within the water quality lifting pool to further power the water, enhancing its self-purification capacity and maintaining long-term water quality. The water, after being lifted, is pumped down through the clean water pool to the other side of the inner lake. This allows for rapid purification of polluted water in the urban inner lake, achieving stable water quality and maintaining long-term effects. This allows for a large-scale water cycle within the inner lake, helping the water regain its self-cleaning function.

[0025] The present invention divides the water in the urban lake into three categories and treats them separately. It is suitable for the surface runoff entering the urban lake during the rainy season, which has the characteristics of "instantaneous, large amount, and intermittent" changes, as well as the uncertainty of the total amount of pollutants entering the urban lake from a single rainfall and the degree of water pollution caused. Therefore, by adjusting the daily processing volume in different treatment conditions, the water quality of the water body can be effectively improved and the water quality improvement system can be efficiently utilized. In addition, by setting a low-flow treatment condition, the life of microorganisms can be maintained, and a sufficient number of microorganisms can be provided for the next conventional treatment condition or high-load treatment condition to ensure the treatment effect. By distinguishing the three conditions, it is possible to adapt to the input flow of different polluted waters and ensure the water quality improvement effect, and it is also possible to save treatment costs and reduce unnecessary waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a top view of the overall structure of the present invention.

[0027] Figure 2 This is a side sectional view of the connection structure of the sedimentation tank, filtration tank, and aeration tank.

[0028] Figure 3 A side cross-sectional view of a water quality improvement pool.

[0029] Figure 4 This is a structural diagram of the ecological filter material module.

[0030] Figure 5 It is a side cross-sectional view of the water quality improvement pool and the water inlet pool.

[0031] Figure 6 A cross-sectional view of the coupling device.

[0032] In the figure, 1 is a sedimentation tank, 11 is a lake water pump well, 12 is a first cover plate, 13 is a first valve well, 14 is a first overflow wall, 15 is a second cover plate, 16 is a sewage pump, 17 is a sewage steel tank, 18 is a ball valve, 2 is a filter tank, 21 is a combined filter unit, 22 is a retaining wall, 23 is an outlet pipe, 211 is a coconut shell, 212 is a sponge, 213 is activated carbon, 214 is a bracket, 3 is an aeration tank, and 31 is a second overflow wall , 32 is the aeration rod, 33 is the water inlet pipe, 4 is the water quality improvement pool, 41 is the ecological filter material module, 42 is the plant module, 43 is the fourth overflow wall, 44 is the guardrail, 45 is the sidewalk, 411 is the bagged filter material, 412 is the bracket, 5 is the water purification pool, 51 is the coupling device, 52 is the retaining wall, 53 is the second valve well, 54 is the submersible pump, 511 is the column, 512 is the grille plate, 531 is the water intake pump, and 6 is the flower box. DETAILED DESCRIPTION

[0033] The technical solutions of the present invention are further explained below with reference to the accompanying drawings and specific embodiments. It is worth noting that the following embodiments are only preferred embodiments of the present invention and should not be construed as limiting the present invention. The scope of protection of the present invention shall be determined by the claims. Any modifications or substitutions made to the technical solutions of the present invention by those skilled in the art without creative effort shall fall within the scope of protection of the present invention.

[0034] Example 1 like Figure 1-6 As shown, a water quality improvement system for bypass treatment of urban lakes comprises a lake water pump well 11 connected to a sedimentation tank 1 via a first valve well 13, the sedimentation tank 1 is connected to a filter tank 2 via a first overflow wall 14, and the filter tank 2 is connected to an aeration tank 3, a water quality improvement tank 4 and a water purification tank 5 in sequence. The polluted urban lake water is transported to the sedimentation tank 1 for sedimentation, and after removing large particles of solid pollutants, the overflow enters the filter tank 2 for filtration under the action of gravity. The additive intercepts and removes small particles of pollutants that are insoluble or soluble in water, and adsorbs some harmful heavy metals and Tiny substances can quickly improve the transparency of water and effectively improve the appearance of water. The filtered water enters the aeration tank 3. When the pollution level of the water is high and the dissolved oxygen content is less than 2 mg / L, the aeration rod in the aeration tank 3 is turned on for nano-aeration to form a micro-oxygen environment. The water is then transported to the water quality improvement tank 4 for further water improvement. Finally, the treated water is transported to the water purification tank 5, discharged from the water quality improvement system, and re-discharged into the urban lake to mix with the untreated water. The cycle is repeated to finally achieve water purification in the urban lake.

[0035] Preferably, a sewage pump 16 is provided at the bottom of the sedimentation tank 1 for discharging the settled sludge in the sedimentation tank 1; a second cover plate 15 is provided at the top; a first cover plate 12 is provided at the top of the lake water pump well 11; the second cover plate 15 and the first cover plate 12 can prevent external pollutants from entering the corresponding positions, and can be opened during maintenance, making it convenient to enter the sedimentation tank 1 or the lake water pump well 11 for equipment maintenance.

[0036] Preferably, a connected sewage steel trough 17 is provided at the bottom of the filter tank 2 and the aeration tank 3. The sewage steel trough 17 is provided with open through holes in the filter tank 2 and the aeration tank 3, which can collect solid matter settled in the filter tank 2 and the aeration tank 3, such as sludge; the sewage steel trough 17 is a sealed pipe passing through the first overflow wall 14 and the retaining wall 22, and a ball valve 18 is provided on the pipe respectively, which is used to prevent water from flowing through the sewage steel trough in the sedimentation tank 1, the filter tank 2 and the aeration tank 3, thereby affecting the flow direction of the water and the water quality treatment effect.

[0037] Further preferably, when sewage discharge and maintenance are required, the water in the sedimentation tank 1, the filter tank 2 and the aeration tank 3 is drained, the two ball valves 18 located in the sedimentation tank 2 and close to the first overflow wall 14 and in the aeration tank 3 and close to the retaining wall 22 are opened, the sewage steel tank 17 is flushed, and the sludge precipitated and collected in the filter tank 2 and the aeration tank 3 is transported to the sedimentation tank 1 through the sewage steel tank 17, and is extracted through the sewage pump 16 in the sedimentation tank 1 and the connected pipeline, and pumped out of the entire water quality improvement system, thereby completing the sludge cleaning and system maintenance.

[0038] Further preferably, the second cover plate 15 is a hot-dip galvanized grille cover plate; and the first cover plate 12 is a single-sided fiberglass grille cover plate.

[0039] Preferably, a combined filtration unit 21 and a retaining wall 22 are provided inside the filter tank 2. The water in the filter tank 2 is filtered out from the top and the water-soluble or insoluble pollutants in the sewage are filtered step by step by the combined filtration unit 21. The retaining wall 22 separates the filter tank 2 from the upper part of the aeration tank 3 to prevent unfiltered water from directly entering the aeration tank 3.

[0040] Further preferably, the combined filtration unit 21 includes a filter medium and a bracket 214, the filter medium is filled between the brackets 214, and there is a certain distance from the bottom of the filter tank 2 to facilitate the collection and discharge of the filtered water; the filter medium includes coconut shell 211, sponge 212 and activated carbon 213 from top to bottom, and adopts a top-in and bottom-out water flow method to filter the water step by step by gravity flow, quickly remove insoluble or water-soluble pollutants, and adsorb some harmful heavy metals and tiny substances, so as to quickly improve the transparency of the water body; an outlet pipe 23 is provided in the retaining wall 22 to transport the water in the filter tank 2 from the bottom to the aeration tank 3 for further aeration treatment.

[0041] Preferably, an aeration rod 32 is provided at the bottom of the aeration tank 3. When the water is seriously polluted and the dissolved oxygen content is <2 mg / L, the aeration rod 32 is opened to form a micro-aerobic environment in the aeration tank 3. A third overflow wall 31 and a water inlet pipe 33 are provided on the side close to the water quality improvement tank 4. The aerated water is transported to the water quality improvement tank 4 through the water inlet pipe 33 in an overflow manner to further improve the water quality.

[0042] Further preferably, the aeration rod 32 is connected to the Roots blower through a stainless steel pipe, and the air volume of the Roots blower during aeration is 50m 3 / h.

[0043] Preferably, the water quality improvement pool 4 is composed of multiple pools, each of which is separated by a fourth overflow wall 43, with a height difference of 0.1-0.3m between the pools, and a total capacity of 1500m 3 .

[0044] Further preferably, the bottom of the water quality improvement pool 4 is provided with an ecological filter material module 41 (density 6 / m 2 ) and plant modules 42, the ecological filter module 41 and the plant module 42 are spaced apart, which improves the ornamental effect while efficiently solidifying nutrients such as nitrogen and phosphorus, promotes nitrogen nitrification / denitrification and phosphorus deposition, and produces a large amount of native oxygen, thereby enhancing the ecosystem's control over phytoplankton and the system's self-purification ability; guardrails 44 and sidewalks 45 are set around it to facilitate pedestrians to pass through.

[0045] More preferably, the ecological filter material module 41 includes bagged filter material 411 and a bracket 412. The bagged filter material 411 contains filter material particles with a particle size of 2-5 mm. After the water body treated in the aeration tank 3 enters the water quality improvement tank 4, its micro-aerobic environment can enable the sludge on the surface of the filter material particles to form a good symbiotic relationship with the microorganisms, creating conditions for the microbial film enriched and grown on the surface of the ecological filter material module to produce short-range nitrification and denitrification, thereby achieving efficient digestion of pollutants such as COD and ammonia nitrogen in the water body. The difference between the aerobic and anoxic environments inside and outside the ecological filter material module 41 is that the outside of the ecological filter material module contacts water and has more oxygen, thus forming an aerobic environment; while the inside of the ecological filter material module contacts water after oxygen consumption, with less oxygen content, forming an anoxic environment, which is anaerobic respiration; the ecological filter material module 41 can improve the contact efficiency between water pollutants and microorganisms, and double the natural digestion capacity of water pollutants.

[0046] Further preferably, the bagged filter material 411 is bagged with a polyethylene mesh with an 80-mesh aperture, and the interior is a silicon-aluminum tetrahedron with a particle size of 2-5 mm. The bagged filter material 411 is evenly layered and stacked on a galvanized bracket 412 with a length × width × height of 3.0 m × 0.8 m × 0.5 m, which effectively solves the blockage problem caused by the sludge formed by the shedding of biofilm and sediment; the filter material particles have high overall performance and a life cycle of 8-10 years. Outside the life cycle, they are partially or completely replaced based on the actual digestion efficiency evaluation.

[0047] Silica-aluminum tetrahedrons are used as ecological filter materials. Their surface pores can provide space for the reproduction and survival of a variety of microorganisms, mainly indigenous microorganisms, and form ciliated microbial films with a thickness of about 2 mm and a film removal size of 0.1-2 cm. Ammonia and nitrogen ions can freely enter and exit, continuously achieving short-range digestion and denitrification. In addition, the micro-nano channels on the surface of the ecological filter material particles become a hotbed for the enrichment, growth, and reproduction of various indigenous microorganisms in the water, and form a biofilm. While adsorbing particles such as ammonia nitrogen, heavy metals, COD, and total phosphorus, they also perform ion exchange and remove pollutants, converting organic matter into nitrogen gas and water for release, achieving the effect of phosphorus and nitrogen removal without causing secondary pollution. Through the long-term performance of the biofilm adsorption and ion exchange removal functions, water pollutants are continuously removed, assisting in the restoration of water quality. The ecological filter material module 41 has good physical adsorption, chemical adsorption, and biocompatibility, which can simplify the sewage treatment process and save costs. It also has a short film formation time and high efficiency, removes nitrogen and phosphorus, removes organic matter, and reduces the COD concentration in the water.

[0048] More preferably, the plant module 42 is composed of foxtail algae and dwarf vallisneria, whose developed root system has an adsorption effect on excessive nitrogen, phosphorus and other nutrients in sewage, and can adsorb heavy metal ions and organic pollutants in sewage and fix them on the root surface or rhizosphere. The biological community attached to the rhizomes of submerged plants maintains its own growth and reproduction needs by absorbing and utilizing nitrogen, phosphorus and other nutrients in the water body, and can absorb, enrich and degrade various organic pollutants; the ratio of foxtail algae to dwarf vallisneria is 1:2, and the layout density of the plant module 42 in the water quality improvement pool is 9 / m 2 .

[0049] Preferably, a coupling device 51 is provided between the water quality improvement pool 4 and the water purification pool 5 to ensure that solid impurities will not re-enter the urban lake to ensure the water discharge effect; a retaining wall 52 is provided on the other side of the water purification pool 5, and a submersible pump 54 is provided at the bottom. The submersible pump 54 is connected to the second valve well 53 to lift the purified water collected in the water purification pool 5 to the second valve well 53, and then discharge it to complete the water quality improvement.

[0050] Further preferably, the coupling device 51 is composed of a column 511 and a grid plate 512; a water intake pump 531 is provided in the second valve well 53 to facilitate the increase of water height and discharge from the system; at the same time, the entire system can be controlled and periodic maintenance is convenient.

[0051] Example 2 (1) Xiufeng Lake in Yiyang City was selected as the water quality improvement target of the urban lake. Through water quality testing, the water quality was divided into three categories: Quasi-IV water, V water and inferior V water. Among them, the COD value of Quasi-IV water is less than 30 mg / L, the ammonia nitrogen content is less than 1.5 mg / L, the total phosphorus content is less than 0.3 mg / L, the permanganate index is less than 10, and the dissolved oxygen is greater than 3 mg / L. The water quality is excellent, with less carbon source, which is basically close to the water quality standard of surface water IV. The COD value of V water is between 30-40 mg / L, the ammonia nitrogen content is 1.5-2.0 mg / L, The total phosphorus content is 0.3-0.4 mg / L, the permanganate index is 10-15, and the dissolved oxygen is 2-3 mg / L. The water quality is poor, and there is a small amount of surface contaminated water entering. Conventional treatment can improve the water quality. The COD value of inferior Class V water is greater than 40 mg / L, the ammonia nitrogen content is greater than 2.0 mg / L, the total phosphorus content is greater than 0.4 mg / L, the permanganate index is greater than 15, and the dissolved oxygen is less than 2 mg / L. There is a lot of surface contaminated water entering, such as in heavy rain. High-load treatment is required to gradually improve the water quality value to Class V water and eventually to quasi-Class IV water. (2) Constructing a water quality improvement system as described in Example 1, the water in Xiufeng Lake is sequentially sent to the sedimentation tank 1, the filtration tank 2, the aeration tank 3 and the water quality improvement tank 4 through the lake water pump well 11, and finally flows into the water purification tank 5. The water with improved water quality is then discharged from the water quality improvement system and allowed to enter Xiufeng Lake again to mix with the untreated water, and the cycle is repeated to achieve the improvement of the water quality of Xiufeng Lake; (3) According to the rainfall, the water quality improvement system is divided into three operating conditions, namely low flow treatment condition, conventional treatment condition and high load treatment condition, which are respectively used to treat the water of Xiufeng Lake with different water qualities, as follows: Low-flow treatment condition: When the water quality of Xiufeng Lake is Class IV water, the lake water pump well 11 is opened to pump lake water into the water quality improvement system with a treatment capacity of 1,000 tons / day to maintain the life of microorganisms in the water quality improvement system and provide a sufficient number of microorganisms for conventional treatment conditions or high-load treatment conditions after the next rainfall. The water flow rate under this condition is 2 m / h. Based on the total water volume of Xiufeng Lake of 160,000 tons, the lake water can be circulated once in 160 days. Therefore, the water flow rate in the lake under this condition is about 3.75 m / d. Conventional treatment conditions: When the water quality of Xiufeng Lake is Class V, the lake water pump well 11 is opened to pump lake water into the water quality improvement system with a treatment capacity of 2,000 tons per day. The water quality improvement system is continuously circulated until the water quality of Xiufeng Lake reaches the target of quasi-Class IV water. The delivery volume of the lake water pump well 11 is then reduced to enter a low-flow treatment condition. While maintaining the life of microorganisms, the water quality is further improved and the environmental capacity of the urban lake water is gradually increased. Based on the total water volume of Xiufeng Lake being 160,000 tons, the conventional treatment condition can achieve the water quality of quasi-Class IV water by running for 18 hours. The lake water can be circulated once every 80 days. Under this condition, the water flow rate in the lake body is about 7.5 m / d. High-load treatment conditions: When the water quality of Xiufeng Lake is inferior Class V water, the lake water pump well 11 is opened to pump lake water into the water quality improvement system with a treatment capacity of 6,000 tons / day, so that microorganisms can multiply in large quantities and improve the ability to remove COD, ammonia nitrogen, etc.; the water quality improvement system is continuously circulated until the water quality of Xiufeng Lake reaches Class V water, at which point the delivery volume of the lake water pump well 11 is reduced to enter the conventional treatment condition; the water quality improvement system is continuously circulated until the water quality of Xiufeng Lake reaches quasi-Class IV water, at which point the delivery volume of the lake water pump well 11 is reduced to enter the low-flow treatment condition, which maintains the life of microorganisms while further improving the water quality and gradually increasing the environmental capacity of the urban lake water; When the water quality of Xiufeng Lake is inferior Class V water, after 6 hours of high-load treatment, the SS and TP removal rates of the effluent water quality are not less than 50% and 35% respectively; under high-load treatment conditions, the effluent flow rate is 12m / h; based on the total water volume of Xiufeng Lake of 160,000 tons, the lake water can be circulated once in 27 days under this condition, so the water flow rate in the lake body is about 22.2m / d.

[0052] Comparative Example 1 Xiufeng Lake in Yiyang City was selected as the target for water quality improvement in the city's inner lakes. Through water quality testing, the water quality was divided into three categories: Quasi-IV water, V water and inferior V water. Quasi-IV water has a COD value of less than 30 mg / L, ammonia nitrogen content of less than 1.5 mg / L, total phosphorus content of less than 0.3 mg / L, permanganate index of less than 10, dissolved oxygen of more than 3 mg / L, excellent water quality, less carbon source, and is basically close to the water quality standard of surface water IV; V water has a COD value between 30-40 mg / L, ammonia nitrogen content of 1.5-2.0 mg / L, total phosphorus content of less than 0.3 mg / L, permanganate index of less than 10, dissolved oxygen of more than 3 mg / L. The phosphorus content is 0.3-0.4 mg / L, the permanganate index is 10-15, and the dissolved oxygen is 2-3 mg / L. The water quality is poor, and there is a small amount of surface contaminated water entering. Conventional treatment can improve the water quality. The COD value of inferior Class V water is greater than 40 mg / L, the ammonia nitrogen content is greater than 2.0 mg / L, the total phosphorus content is greater than 0.4 mg / L, the permanganate index is greater than 15, and the dissolved oxygen is less than 2 mg / L. There is a lot of surface contaminated water entering, such as in heavy rain. High-load treatment is required to gradually improve the water quality value to Class V water and eventually to quasi-Class IV water. (1) Quasi-Class IV water: In the absence of external interference and auxiliary purification methods, it takes 160 days to purify the water quality to meet the surface water Class IV standard, that is, COD is <30 mg / L, ammonia nitrogen content is <1.5 mg / L, TP content is <0.3 mg / L, and the water flow rate is 4m / h; (2) Class V water: Without external interference and auxiliary purification means, it takes 80 days to purify the water quality to meet the surface water Class IV standard, that is, COD <30 mg / L, ammonia nitrogen content <1.5 mg / L, TP content <0.3 mg / L, and water flow rate of 8 m / h; (3) Poor Class V water: In the absence of external interference and auxiliary purification methods, it takes 100 days to purify the water quality to meet the Class IV standard of surface water, that is, COD is <30 mg / L, ammonia nitrogen content is <1.5 mg / L, TP content is <0.3 mg / L, and the water flow rate is 12m / h.

Claims

1. A system for improving water quality in an urban lake bypass, characterized by: The invention comprises a lake water pump well (11) connected to a sedimentation tank (1) via a first valve well (13), the sedimentation tank (1) connected to a filter tank (2) via a first overflow wall (14), the filter tank (2) connected in sequence to an aeration tank (3), a water quality improvement tank (4) and a water purification tank (5); a combined filter unit (21) and a retaining wall (22) are provided inside the filter tank (2).

2. The urban lake bypass water quality improvement system according to claim 1, characterized in that: The sedimentation tank (1) is provided with a sewage pump (16) at the bottom and a second cover plate (15) at the top; the lake water pump well (11) is provided with a first cover plate (12) at the top; and sewage steel troughs (17) are provided at the bottoms of the filter tank (2) and the aeration tank (3), and a ball valve (18) is provided in the sewage steel troughs (17).

3. The urban lake bypass water quality improvement system according to claim 1 is characterized by: The combined filter unit (21) comprises a filter medium and a bracket (214), wherein the filter medium comprises, from top to bottom, coconut shell (211), sponge (212), and activated carbon (213); and a water outlet pipe (23) is provided in the retaining wall (22).

4. The urban lake bypass water quality improvement system according to claim 1, characterized in that: The aeration tank (3) is provided with an aeration rod (32) at the bottom, and a third overflow wall (31) and a water inlet pipe (33) are provided on one side; the water quality improvement tank (4) is composed of a plurality of tank bodies, each tank body is separated by a fourth overflow wall (43), and the height difference between the tank bodies is 0.1-0.3m.

5. The urban lake bypass water quality improvement system according to claim 4 is characterized by: The water quality improvement pool (4) is provided with an ecological filter material module (41) and a plant module (42) at the bottom, and is surrounded by guardrails (44) and sidewalks (45).

6. The urban lake bypass water quality improvement system according to claim 5, characterized in that: The ecological filter material module (41) comprises bagged filter material (411) and a bracket (412).

7. The urban lake bypass water quality improvement system according to claim 1 is characterized by: A coupling device (51) is provided between the water quality improvement pool (4) and the clean water pool (5); a retaining wall (52) is provided on the other side of the clean water pool (5); a submersible pump (54) is provided at the bottom; and the submersible pump (54) is connected to the second valve well (53).

8. The urban lake bypass water quality improvement system according to claim 7, characterized in that: The coupling device (51) is composed of a column (511) and a grid plate (512); a water pump (531) is provided in the second valve well (53).

9. An application method of the urban lake bypass water quality improvement system according to any one of claims 1 to 8, characterized in that: The steps include: (1) Based on the water quality, the water in the urban lake is divided into Class IV, Class V and Class V; (2) Introducing water from different types of urban lakes into the water quality improvement system for treatment: Quasi-Class IV water: The water quality improvement system is a low-flow treatment condition with a treatment capacity of 800-1200 tons / day; Class V water: The water quality improvement system is in conventional treatment conditions, with a treatment capacity of 1,700-3,000 tons / day; Poor Class V water: The water quality improvement system is in high-load treatment condition, with a treatment capacity of 5500-6300 tons / day; (3) After the treatment is completed, the water in the water quality improvement system will be discharged to the other side of the urban lake for cyclical treatment.

10. The application method according to claim 9, characterized in that: The COD of the quasi-Class IV water described in step (1) is less than 30 mg / L; the COD of Class V water is 30-40 mg / L; and the COD of inferior Class V water is greater than 40 mg / L.

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