Recently, Zhang panyue, a professor of Beijing Forestry University, shared a report entitled "technology and application of cascade wetland ecological restoration and water quality purification" in the "practical application of wetland technology in Beijing Tianjin Hebei water project" seminar series sponsored by jiei Industrial Research Institute.
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I would like to thank all the experts for their guidance and careful arrangement.
Zhang Pan Yue
Professor of Beijing Forestry University
This project belongs to the project of "research and demonstration on Key Technologies of water ecological environment improvement and water safety guarantee in Baiyangdian and Daqinghe River Basins (xiong'an New Area)". In view of the outstanding problems faced by Baiyangdian Lake Wetland at present, the integration of water environment management and water ecological restoration technology is carried out with the main goal of water environment security guarantee and water ecological function restoration of Baiyangdian Lake wetland; the ecological restoration strategy of typical Grass Lake (Baiyangdian Lake) in North China is put forward to reduce the water pollution load from multiple perspectives, so as to ensure the ecological security At the same time, improve the self purification function of the water body; adopt the comprehensive treatment technology to restore and reconstruct the near natural wetland and the wetland of returning farmland to wetland, so as to provide a comprehensive scientific and technological support for the improvement of the main indicators of water quality into the lake (excluding total nitrogen) to the class IV standard of surface water environmental quality and the stability and health of wetland ecosystem.
Three challenges of water quality improvement and ecological restoration in Baiyangdian Lake: less water entering into the lake, dirty water and continuous and serious degradation of wetland ecological function
The research team found that the water quality improvement and ecological restoration of Baiyangdian Lake are mainly faced with three challenges:
There is basically no natural runoff in the upper reaches of Baiyangdian Lake, and the water from the river entering the lake mainly comes from the tail water of the upstream sewage treatment plant. The long-term high load pollution causes the loss of the self purification capacity of the upper reaches of the river, and there are various kinds of garbage, breeding, living and other pollution discharged along the way, resulting in poor water quality in the lake.
The accumulation of endogenous pollutants, pesticide and fertilizer, and the input risk of rural non-point source pollution are high in Zao Lake Wetland and Ma Peng Lake wetland;
The ecological space of Baiyangdian Lake is single, the wetland entering the lake is swamped and farmed obviously, the wetland area is decreasing year by year, the biodiversity is destroyed seriously, the ecological structure and function are deteriorating continuously, so it is difficult to guarantee the water quality of Baiyangdian Lake area.
Baiyangdian Lake is composed of 143 lakes and more than 3700 ditches of different sizes. The upper reaches of the main lake area are seriously swamped and the mabeng lake is completely farmed. The water from Fuhe River and Xiaoyi River in the upper reaches flows directly into the main lake area along the riverway of zao'an and mabeng lake, and the latter has no ecological environmental effect.
According to the ecological environment protection requirements of the overall planning of shuishitiao and Xin'an new area, the research group carried out the research and demonstration of ecological restoration and water quality purification of the upper reaches of Baiyangdian River and wetland, and put forward the targeted solutions to the three problems, forming the cascade ecological restoration and water quality purification from the upper reaches of the river to the buffer zone of the incoming wetland, and then to the algal lake and the mapingdian wetland The technical system and key control links are fully covered to ensure the improvement of water quality entering Baiyangdian main lake area.
Ideas and achievements: River water quality improvement - buffer zone pollution reduction - near natural wetland and wetland ecological restoration after returning farmland to Wetland
In view of the problems of poor water quality in the upstream of Baiyangdian area, weak self purification capacity of rivers and wetlands entering the lake, and great impact on water quality and water ecological environment in the lake area, the solution involves many research contents, wide technical fields and no large-scale application experience. The focus of this project is to expand the application scope of existing technology and integrate innovation, to solve the constraints and problems existing in the application of various technologies at the same time.
1. In view of the heavy pollution and weak self purification capacity of the rivers entering the lake, it is urgent to build the river ecosystem and enhance the self purification capacity
In view of the situation that the water from the upper reaches of the Fuhe River and Xiaoyi river is mainly the tail water of the sewage treatment plant, the subject carried out the research on the multi-functional coupling ecological restoration technology of the new section of the Fuhe River and Xiaoyi River, and constructed the integrated technology of River Purification and river ecological restoration. In order to improve the purification of river water quality, the technologies of sediment environmental protection and desilting, river ecological patch construction, river ecological restoration and comprehensive treatment of riverside environment were explored.
First of all, the paper studies the pollution status of the river water and sediment of the Fuhe River and Xiaoyi River, analyzes the water environmental capacity of the new section of the Fuhe River and Xiaoyi River, and puts forward the main countermeasures and measures for the total water pollution control.
On this basis, combined with ecology The concept of "patch corridor matrix" remoulds the river course, and constructs the ecological patch restoration system of the river course under the appropriate conditions; the compound ecological floating island is designed, which utilizes the plant absorption, matrix adsorption, and microbial action, and introduces the sulfur autotrophic denitrification principle to achieve better nitrogen and phosphorus removal effect; according to the river course conditions of Fuhe River and Xiaoyi River, the river course is constructed in the appropriate area Inner wetland ecosystem.
In terms of comprehensive regulation of the bank, gabion / Renault mattress and pine pile are mainly selected for ecological bank protection construction.
2. In view of the poor quality of the incoming water and the large fluctuation of the load, the buffer zone of the incoming wetland is constructed to reduce the pollution
In view of the serious pollution of Fuhe River and Xiaoyi River and the sharp increase of pollution load during the rainstorm, the research group constructed wetland buffer zone in the upper reaches of zao'an and mabeng lake to reduce the impact of the water from the upper reaches on the natural wetlands near the lower reaches.
According to the landform and land use status around the entrance of the lake, the design form of the wetland buffer zone is determined; the disposal process unit configuration of the wetland buffer zone for removing suspended matter, organic matter, nitrogen, phosphorus, etc. in the upstream water is proposed, and the pollutant purification system mainly consisting of biodegradation, plant absorption and matrix interception is constructed to promote the efficient removal of pollutants.
The wetland buffer zone adopts the configuration of ecological pond, subsurface flow wetland and plant pond. Among them, the initial reduction of particulate pollutants in the ecological detention pond; the enhanced removal of pollutants in the functional wetland system through the substrate (zeolite and steel slag, supplemented with gravel), aquatic plants and microbial systems with high nitrogen and phosphorus removal efficiency; the plant pond system tends to be close to the natural wetland ecosystem, and the construction of aquatic biological system is based on the local plants and benthos in Baiyangdian Lake.
3. In view of the lack of water purification and ecological functions of the wetland entering the lake, a good natural wetland ecosystem is gradually formed through near natural restoration and reconstruction
In view of the problems of ecosystem degradation, no ecology and water purification function in Zao lake and Ma Peng lake wetlands, the project explores the near natural wetland restoration technologies such as environmental protection and dredging of polluted sediment, water system connection, hydrodynamic optimization, animal and plant microbial ecological restoration through near natural ecological restoration and ecological reconstruction technology, so as to economically and effectively realize the wetland into the lake The water purification project of the project, formed the ecological restoration strategy of the typical grass type lakes in the north, and promoted the transition of Zao lake and Ma Peng lake to form a good natural wetland ecosystem.
First of all, according to the pollution source and pollution space, reasonable wetland pollution removal is carried out.
According to the pollution assessment of sediment and soil in Zao lake and Ma Peng lake, the total nitrogen and phosphorus in this area are in the rich and extremely rich level, and the total phosphorus is in the medium level; after wetland restoration, both nitrogen and phosphorus are released to a certain extent, and even the water quality of the overlying water greatly exceeds the class V standard of the surface water, and some pollution removal is required in some parts of the region.
Secondly, combined with hydrodynamic optimization, improve the connectivity of wetland water system.
According to the topography of zaopeng lake, by Delft3D simulation, the path of water from the upper reaches of Fuhe River to zaopeng lake is optimized to realize water system connection; through the ecological landscape design of deep pool, shoal, ditch and ecological island, the spatial pattern of mabeng Lake wetland is re planned, optimized and ecological reconstructed; the hydrodynamic process and pollutant removal effect in zaopeng lake and mabeng lake are simulated; through the basement micro The improvement of topography and site conditions promotes the optimization of water flow process, ecosystem restoration and pollutant reduction.
Third, the ecological restoration is mainly through the configuration, optimization and restoration of near natural aquatic organisms.
According to the natural characteristics of Baiyangdian Lake, the emergent plants mainly composed of reed, the submerged plants mainly composed of spirulina, goldfish and verticillata are the best combination of plants for ecological restoration of algal lake and stable wet land food chain with the support of Zoobenthos. In order to ensure the effect of pollutant removal under the condition of water level fluctuation and low temperature, the suitable When functional bacteria are added.
Technology application and Expectation: purification of water quality from upstream, restoration of wetland ecological function and tiandian lake scenery of weihaitai
The key work of Hebei provincial Party committee and provincial government in 2019 is the construction of ecological environment in xiong'an new area. From the ecological restoration of river channel to the construction of wetland buffer zone, to the construction of large-scale wetland, it is the key work of ecological environment construction. The organic combination of these three eco-environmental projects can guarantee the water quality of Nanliuzhuang section to reach the standard. At present, the demonstration projects of Xiaoyi river channel and wetland buffer zone of Fuhe River have been started.
The comprehensive environmental treatment of the new section of the Fuhe River and Xiaoyi river is 16.3 km and 6.4 km respectively, including dredging works, garbage removal and sediment removal. In addition, seven river wetlands are constructed in the Fuhe River, and ecological restoration of the river course and the riparian zone are carried out. Seven river wetlands are equipped with corresponding plant, microorganism and animal systems according to the specific conditions of the river.
The water purification project of the Fuhe River estuary is 4 km2 in total, with the designed treatment capacity of no less than 250000 m3 / D, and the water purification project of Xiaoyi River estuary is 1.98 km2 in total, with the treatment capacity of no less than 150000 m3 / d. The water purification project mainly includes the ecological pond in front, the key subsurface flow wetland and the subsequent aquatic plant pond. Ecological pond system includes aerobic pond, ecological pond, artificial water and grass, ecological island, etc. The subsurface flow wetland is divided into many treatment units, and the filler is mainly gravel and steel slag. According to the law of near natural wetland, there are submerged plant pond, floating leaf plant pond, lotus pond, Reed Sea terrace and so on.
At present, the construction of large-scale algal Lake wetland is in the stage of pre feasibility study and feasibility study.
Through the research and project demonstration of the project, a cascade wetland ecological restoration technology system has been formed, including the river channel into the lake, the buffer zone of the wetland and the conversion of farmland to the lake, the comprehensive treatment of the rivers of Fuhe River and Xiaoyi River, the water quality purification project of the estuarine wetland, and the restoration project of the large-scale algal lake and mapingdian ecosystem, so as to realize the water quality purification of the upstream water, and at the same time restore the wetland ecological function and Baiyangdian Lake The tiandian lake scenery of weihaitai supports the construction of Daqing River Ecological Corridor in Baiyangdian.
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