Professor An Shuqing of Nanjing University, who is in charge of the river water ecological restoration project of Huaihe River, won the "Outstanding Wetland Scientist" award.
In September 2016, the 10th International Wetland Conference was successfully held in Changshu City, Jiangsu Province. A special report session was held on the National Major Project of Water Pollution Control and Treatment Science and Technology (referred to as "Water Project"), and the relevant person in charge of the Water Project Management Office systematically introduced the related work and achievements of water project in supporting wetland protection and ecological restoration of rivers and lakes in China. At the meeting, Professor An Shuqing of Nanjing University, who is in charge of the river water ecological restoration project of Huaihe River and the organizer of the 10th International Wetland Conference, was awarded the "Outstanding Wetland Scientist" award by the International Ecological Association, becoming the first person in Asia to win this honor. Professor An Shuqing’s scientific achievements have been recognized by the wetland academic circles in the world, which is a microcosm of the achievements made by the water project in controlling the pollution of rivers and lakes and other world problems.
In order to achieve sound and rapid economic and social development in China, relieve the pressure of energy, resources and environment in China, and solve the major bottleneck problem of water pollution science and technology that restricts China’s social and economic development, according to the Outline of the National Medium-and Long-Term Scientific and Technological Development Plan (2006-2020), China has set up a water project from the 11th Five-Year Plan, with six themes, including river theme and lake theme. In the past 10 years, with the continuous support of the national water project, China has made a major breakthrough in the research and development and application of water ecological protection and restoration technologies for rivers and lakes. The Liaohe River took off its hat, and Nansi Lake was selected as the first batch of ecologically sound lakes in China … … Aiming at the key problems existing in different regions and wetlands, the water project has carried out joint research on technology, technology, engineering, materials and equipment, and the relevant technical achievements have been popularized in more than 20 provinces and cities across the country, which has achieved remarkable results in improving the water ecological environment of rivers and lakes.
Break through the innovative technology of river water purification and promote the upgrading and improvement of river water quality
There is a big gap between the environmental quality standard of surface water and the discharge standard of water pollutants, which leads to the decline of self-purification ability of rivers and the deterioration of water quality, and becomes a polluted river.
In view of the lack of black odor and water purification capacity of rivers, the water project is closely combined with the actual needs of comprehensive river regulation, and key technologies such as ecological river course, coupling of multi-stage constructed wetland water purification, coupling of near-natural river course and floodplain land-soil lateral infiltration, collaborative control of source control and emission reduction in industrial parks and non-point source runoff pollution have been developed to further reduce the pollutant concentration of urban domestic sewage and industrial wastewater discharged up to the standard in the upper reaches of rivers.
"If you want to control Huaihe River, you must first control Yinghe River, and if you want to control Yinghe River, you must first control Jia Luhe". Aiming at the environmental management of Huaihe River basin, water special research and development technology is an important tributary in Jia Luhe — — A demonstration of river engineering with a total length of about 19km was carried out in Suoxu River. The project achieved an average reduction of 22% in organic pollutants, 89% in ammonia nitrogen and 42% in total phosphorus in the demonstration reach, and the water ecological environment was effectively improved, from "smelly canal" to "water scenic spot". The demonstration project area supported the water pollution control and water environment improvement in Jia Luhe River Basin, and promoted the successful application of Zhengzhou section of Tongji Canal of China’s Grand Canal.
In addition, the R&D technology was used to carry out engineering demonstration in the airport economic zone of Tianjin Port Bonded Zone in the middle reaches of Haihe River, and the overall scheme of comprehensive management of landscape water bodies and water quality improvement in the park was implemented, and a demonstration area of 24km2 was built. The Xisidao Wetland Purification Project with a daily treatment capacity of 0.65×104 t was completed, and the effluent reached the standard of Class IV water body. After comprehensive management, the overall water quality in the demonstration area was improved in 2016, and the average concentrations of organic pollutants and ammonia nitrogen in the main monitoring sections decreased by 34% and 79% respectively compared with 2013.
The R&D technology has also been popularized and applied in Liaohe River, Taihu Lake and other regions, covering an area of more than 2,600 mu, eliminating a number of black and odorous rivers, deeply purifying the inferior V and V water and maintaining the water quality above Class III, which has made important contributions to pollution reduction and water quality stability in river basins.
Carry out the regulation of environmental flow and the allocation of biological functional groups to restore the vitality of damaged rivers
The serious damage of water ecosystem is an important reason for the decline of self-purification ability and biodiversity of river water bodies, which in turn leads to the deterioration of water environment in downstream lakes. Aiming at the ecological destruction problems such as insufficient ecological basic flow of rivers, fragmentation of wetland habitats, channelization of rivers, and decline of self-purification ability, the water project carries out research and development and integrated application of water ecological restoration technologies for floodplains and rivers according to different geographical topography and characteristics of aquatic ecological communities.
In the floodplain area, the water project integrates practical technologies of wetland ecological water replenishment and water level control, such as ecological ditches, permeable subgrade and landform modification. The rapid recovery technology system of typical wet plants, such as "root transplanting" of typical wetland vegetation Carex tatarinowii, "strip-shaped close planting cutting" of marsh willow, and "directional and fixed-distance excavation" of degraded Typha wetland, was initiated and constructed. Clever use of the characteristics of water deflection to the right in the northern hemisphere to plant wetland plants in rows, greatly improving the pollutant interception ability of floodplain wetlands; Make full use of the water ecological characteristics of river branches and oxbow lakes, reconstruct biological habitats and ecological corridors, reduce the flow velocity and improve the water purification ability; By densely planting Salix riparia on the eroded bank, the erosion of the bank can be reduced, and at the same time, special habitats can be provided for fish spawning, larval refuge, waterfowl habitat and food supply, thus forming a benign interaction between the revetment of Salix riparia and biological habitat.
In the river zone, based on the diagnosis and classification of river water ecological health, it broke through the key technologies such as the allocation of water ecological functional groups and the stable construction of food chain, and integrated the technical system of "water ecological restoration based on the definition of environmental flow threshold"; The overall scheme of water resources allocation for ecological sluice and dam is put forward, which makes full use of the beach space in front of sluice, breaks through the key technologies of river wetland construction and ecological maintenance in front of sluice, and adopts the circulating purification form of bypass surface wetland and solar aeration underflow wetland to build a healthy aquatic ecosystem, forming a purification system and ecological interaction zone where the main river and bypass wetland interact and circulate, thus effectively improving the purification efficiency of river and beach. Build a deep pool shoal habitat, and through the joint release of aquatic plants, fish and shellfish, create a three-dimensional suspended habitat in the deep water area, form a diverse and stable river water ecosystem, and achieve good removal effects on organic matter, suspended particulate matter, nitrogen, phosphorus and other pollutants.
A demonstration area with a length of 111km was established in Fujinjiang section of the lower reaches of Songhua River. The wetland coverage rate reached 61%, the biomass per unit area increased by 31%, the population of typical wetland waterfowl increased obviously, and indigenous fish such as lamprey appeared one after another in Northeast China. The technical system of "Water Ecological Restoration Based on the Definition of Environmental Flow Threshold" was demonstrated in the Jia Luhe River Basin of Huaihe River. The total length of the demonstration reach was 90km, and the biological species richness of the water ecological restoration reach was increased by 66%. The six biological functional groups of submerged plants, emergent plants, zooplankton, fish and birds were intact, and the food chain was restored. Dissolved oxygen is increased from less than 2mg/L to more than 8mg/L; The number of plant species and animal species increased by 46% and 41% respectively, while the chemical oxygen demand and ammonia nitrogen concentration decreased by 80% and 66% respectively, and the water quality and water ecological quality in Jia Luhe improved significantly. The demonstration project of river wetland in the future science and technology city is supported by the special water technology in the North Canal, with a total demonstration water surface area of 2.9×105 m2. The multi-functional three-dimensional ecological floating bed of 5000 m2 is arranged in the project, and emergent plants and submerged plants are planted, and filter-feeding fish are stocked. The working efficiency of the new solar water-lifting aerator is more than 10% higher than that of related products. The main water quality indexes of the demonstration project meet the Class IV standard of surface water. There are 32 species of phytoplankton, 26 species of zooplankton, 22 species of benthos and 15 species of aquatic plants in the wetland.Formed a beautiful river wetland scenery.
The special research and development technology of water has been widely promoted and applied in river management, ecological restoration and biodiversity conservation in Huaihe River, Songhua River, Haihe River, Liaohe River, Taihu Lake and other regions. Indigenous fish have returned home, and rare migratory birds have returned, reappearing the beautiful landscape of "beautiful water, birds singing and fish playing, harmony between people and water", which has promoted the continuous improvement of water ecology in the basin.
Improve the ecological barrier of estuary and lakeside zone, and secure the last gate for sewage to enter the lake.
Lakeside zone and estuary into the lake are the most important land-water ecotone in the inland, which is rich in biodiversity and has many ecological functions, such as purifying the water entering the lake, stabilizing the lake coastline, delaying floods and so on. Lakeside zone is also often an area with high interference intensity from human activities in lake basin. Human activities, such as land reclamation, fish farming and beach development around the lake, have caused the lakeside wetland to be occupied, the biodiversity of the wetland has decreased, the carrying capacity of the ecological environment has been seriously weakened and the ecological self-purification ability has been greatly reduced.
With the support of the special water project, in view of the serious problems existing in large shallow eutrophic lakes such as Taihu Lake, such as hardening of lakeside zone, encroachment of wetlands, poor water quality in estuaries and tributaries, and accumulation of algal blooms, the key technologies such as pre-reservoir treatment in estuaries, ecological restoration of levee lakeside zone, ecological construction and functional restoration of river network lake buffer zone, and delineation of buffer zone range have been broken through, and the ecological restoration and stability maintenance models of gentle slope and steep bank lakeside zone have been developed for typical lakes such as Erhai Lake in the initial stage of eutrophication.
With technical support, Zhushan Bay in Taihu Lake Basin was built with a demonstration project of 10km, with 27ha of wetland and forest grassland. After the completion, the total nitrogen and total phosphorus concentrations in the branch were reduced by 58% and 21% on average, and the vegetation coverage rate in the demonstration area reached 87%. A demonstration project of 232ha was built in Gonghu Bay, and the water quality of the lakeside was maintained at Class IV surface water all the year round, with more than 50 species of aquatic plants. Support the construction of 18km lakeside ecological restoration demonstration project and 100ha buffer zone demonstration zone in Erhai Lake, and promote the construction of 92km lakeside zone in Erhai Lake, and increase the vegetation species in the gentle slope lakeside zone demonstration zone from 24 to 45; The number of epiphytic algae in the demonstration area of steep shore lakeside zone increased by 10%~28%; The total nitrogen and total phosphorus of runoff in the buffer zone demonstration area decreased by 32% and 48% respectively.
R&D technology has been widely applied in Taihu Lake, Erhai Lake, Nansi Lake, Chaohu Lake, Dianchi Lake and Dalian Lake. Relevant technical achievements have been successfully applied in the 13th Five-Year Plan for Water Environment Protection and Governance in Erhai Lake Basin, and the Technical Guide for Ecological Restoration of Lakeside Zone has guiding significance for the ecological restoration of lakeside zone of lakes with good water quality in China.
Innovative lake ecological restoration and cyanobacteria bloom control technology to restore a healthy water ecosystem.
Aiming at the problems of heavy pollution load, declining biodiversity and high risk of eutrophication in natural lakes, Water has specially developed some new technologies, such as the construction of lake food chain, the control of algae source load in areas where cyanobacteria are easy to gather, "ecological jellyfish" and "ecological film mulching", which have broken through the advanced technologies such as floating plants driven by wind/light+biological film mulching+enhanced algae removal by micro-nano aeration, food web reshaping and multi-trophic biological manipulation, and formed the ecological interception of pollutants entering the lake estuary, shallow water.
Aiming at the problems of high nutrient load in urban landscape lakes, uneven distribution of water quality in time and space, abnormal proliferation of algae in spring, and low transparency of water body affecting the landscape, the water project has broken through the technologies of nitrogen reduction by denitrifying biological filter, optimization of ecological introduction, distribution and drainage in lakes, and ecological algae control in spatial heterogeneity, and integrated a complete set of technical systems for water quality improvement and ecological restoration of urban landscape lakes with ecological engineering as the core.
The special research and development technology of water is used in typical lakes in Taihu Lake basin and important flood storage lakes for water supply and ecological regulation in the upper reaches of Taihu Lake — — A 14km2 project demonstration was carried out in Gehu Lake, and a 2.4km2 pre-reservoir project demonstration area and a 34ha aquatic vegetation restoration area were built. By the end of 2015, nearly 13.4 million silver carp, bighead carp and summer flowers, 980,000 winter fish, 170,000 snakehead fish, 350,000 mussels and 56 tons of snails were released, and five cyanobacteria filters were arranged. The water quality in the pollution control area has been obviously improved, the load of total nitrogen and total phosphorus has been reduced by more than 20%, and the coverage rate of aquatic vegetation in the ecological restoration area has reached more than 50%, greatly improving the self-purification ability and storage and purification function of the lake. This achievement ensured the successful convening of the 8th Changzhou Flower Expo in China in 2013, and made outstanding contributions to the construction of the wetland exhibition area and the improvement of the water quality of the main exhibition hall.
A water diversion and nitrogen reduction project with a scale of 5×104 m3/d was built in the West Lake, and the total nitrogen in the effluent was improved from worse than Grade V to Grade IV, and the total nitrogen in the lake was reduced by more than 18t per year. By optimizing the water diversion through the flow field with the scale of 7×104 m3/d, the circulating optimized water distribution system in the lake is established, and the submerged plant community structure with multiple spatial levels is constructed in the water area of about 1km2, which effectively reduces the biomass of algae and forms the landscape of "underwater forest". This achievement provided a strong water environment guarantee for the success of G20 Summit in 2016. The clear and full West Lake and beautiful water landscape left a deep impression on Chinese and foreign guests.
The technical achievements of lake wetland reconstruction and ecological restoration have been widely used in Taihu Lake, Dianchi Lake, Chaohu Lake, West Lake, Erhai Lake, Nansi Lake and Dalian Lake, and achieved remarkable results.
The new technology of constructing constructed wetland and ensuring sustainable operation has been developed, and the water purification function has been strengthened.
In view of the water quality guarantee problems caused by the weak self-purification ability of river and lake ecosystems, the upstream discharge of wastewater and non-point source pollution, the water project has built artificial wetlands according to local conditions in the downstream of important sewage outlets, the branches flowing into the main stream, the rivers entering the lake and other places, and the sewage will enter the main stream or lake after being purified by the artificial wetlands to further improve the water quality. Constructed wetland is regarded as the ultimate guarantee for the stability of water quality in the lake, which breaks through the problems of low mass transfer efficiency and poor operation stability in the application of large-scale constructed wetland projects. Research and develop spatial structure optimization technologies such as multistage series connection, circular flow, nested mixed flow and bidirectional regulation of water flow, give full play to the purification potential of subsurface flow and surface flow constructed wetlands, and realize the removal rate of organic pollutants and ammonia nitrogen increased by about 18% and 35% respectively; The research and development of technologies such as natural aerobic strengthening, optimal configuration of bow shed and seasonal plants have solved the problem of long-term and stable operation of the project and achieved 70% ammonia nitrogen removal rate in winter.
In the water project, a six-stage series surface flow scale constructed wetland water purification project was built in Nansi Lake, with a wetland area of 667ha and a purified river water of 4×104m3/d, and the effluent reached the Class III standard of surface water. The project was officially approved by the State Forestry Administration as a national wetland park and was selected as one of the "Top Ten Charming Wetlands in China" by the State Forestry Administration. A demonstration project of constructed wetland in Shuanghe River, Xinmi, Huaihe River was established in xinmi city, with a daily treatment capacity of 1.2× 105m3/d. After operation, the effluent can be upgraded to Class III water, which provides 4.38×107m3 clean water for Shuangyue River every year, and the cost of water treatment per ton is only 0.1 yuan.
The technical achievements have been widely applied in the Nansi Lake basin of Huaihe River, with 730 ha of constructed wetland project, 1.33×104 ha of returning farmland to humidity, and two national wetland parks supported. Fish, such as Neosalanx salanx and Pseudosalanx salanx, which have been extinct for many years, began to grow again, with 80 species of aquatic higher plants, 52 species of fish and 52 species of benthos. Fifty-two rare waterfowl white-naped cranes and peach jellyfish, which are extremely sensitive to water quality, have been found in the basin. The main water quality indexes in the lake area jumped from the surface water worse than Grade V to Grade III. Nansi Lake, once heavily polluted, presents a beautiful wetland scenery with lotus leaves connecting the sky, lotus flowers reflecting the sun, rippling reeds, egrets gathering and clear water gurgling.
The special research and development technology of water has built a multi-stage artificial wet 33.5ha in the estuary area of Nanfeihe River in Hefei City, purified the heavily polluted river water by 6×104m3/d, and the effluent quality reached Class IV of surface water, with a guarantee rate of more than 83%. The annual reduction of nitrogen, phosphorus and permanganate index of Nanfeihe River reached 93.2 t, 5.3 t and 143.8 t, respectively, which made a contribution to improving the water quality of Chaohu Lake.
At the same time, the technical achievements have been popularized and applied in the constructed wetland of du cun Temple in Qingfei River, Henan Province. The constructed wetland has been built for 16.2ha, and the tail water of sewage plant has been purified for 6× 104 m3/d. The effluent quality has reached Class IV of surface water, and the guarantee rate is over 80%. The purified water body is used to improve the water quality of heavily polluted Qingfei River and ensure the ecological basic flow of rivers in water-deficient areas in the north.
Innovate the management system of rivers and lakes, and form a joint force of ecological management of rivers and lakes.
Aiming at the problem of serious pollution and extreme water shortage in rivers and lakes in the north, the water special research group guides and explores new modes of river management and protection through innovative management system and mechanism. In heavily polluted areas, taking river basins as a whole, exploring and delineating large-scale river protection areas, strengthening administrative management, and formulating protection regulations to provide administrative and legal protection for river management and protection; Establish and improve the basin water quality model, carry out the calculation of water environmental capacity and water environmental quality — Identification of quantitative relationship of emission, optimization of emission reduction strategy and technical scheme of main pollutants in water body, evaluation of pollution reduction and water quality improvement effect, support the formulation and release of the most stringent pollutant emission standards and long-term mechanism of regional compensation for water environment; Breakthrough the key technology of total pollutant control based on the improvement of water environment quality, and bring urban non-point sources, agricultural sources and industrial sources into the analysis system of full-caliber pollution sources in the basin to solve the problem of total pollutant control; Research and development of riparian zone natural enclosure technology and management methods, construction of tributary estuary wetland pollution prevention and control scheme, implementation of ecological returning farmland measures, to solve the long-standing problems of riparian zone management vacancy, people and water competing for land and serious tributary estuary wetland pollution.
The water special research and development technology supported the delineation of China’s first large-scale river protection zone in Liaohe River, and formulated the Regulations on Liaohe River Protection Zone in Liaoning Province. A comprehensive demonstration zone for water pollution control and water environment treatment in Liaohe Nature Reserve has been built up to 100km2, and the water quality in the demonstration zone has reached the Class IV standard. The vegetation coverage rate in the riverside zone is over 90%, and the area of restored wetlands is over 6.67×104ha, and the functions of fish, birds and ecosystems have been basically restored.
The management and management technology of Liaohe nature reserve has been widely applied in the basin, with a total enclosure area of more than 5×104ha, and the ecological corridor with a length of about 538km and an area of 4.4×104ha in Liaohe River has been completed. The number of species of plants, fish and birds has increased from 187, 15 and 45 before enclosure to 226, 33 and 81 at present, among which rare birds such as black-billed gull and gull, and rare fish such as Coilia ectenes, Silurus japonicus and betta have reappeared in the nature reserve. The proportion of water bodies whose main stream water quality is better than Class III is increased by 10%, which reproduces the pleasant scenery of Liaohe River with abundant water and lush grass, clear water and green shore.
In addition, the circular flume with its own intellectual property rights is used to simulate the flow characteristics of natural rivers, and the parameters of water quality model are optimized in combination with indoor control experiments, so as to construct the total control technical model of the North Canal (Beijing Section) based on the improvement of water environment quality, and realize the operational operation.
The water quality model of the North Canal (Beijing Section) supports the promulgation and implementation of the two most stringent local standards in Beijing: Pollutant Discharge Standard for Urban Sewage Treatment Plants (DB11/890-2012) and Integrated Discharge Standard for Water Pollutants (DB11/307-2013). Supported the formulation of "Measures for Regional Compensation of Water Environment in Beijing" and "Implementation Rules for Cross-district and County Boundary Water Body Cross-section Index Evaluation", which broke the previous situation of sewage treatment in Beijing, mobilized the enthusiasm of sewage treatment in all districts and counties, and formed a new situation in which the upstream and downstream of the river basin cooperated with each other and all districts cooperated in water control. In 2016, the compensation withheld in each quarter decreased significantly year-on-year, reflecting the obvious promotion of the implementation of water environment compensation in the basin to improve water quality.(Tong Kenan)
