Project Introduction:

Dongshan Lake Park was built in 1959, with a water area of about 33.50,000 m2, is one of the four ecological conservation lakes in Guangzhou, adjacent to the Guangdong Provincial Party Committee compound and Zhudao Hotel。As a semi-open water body, Dongshan Lake needs to bear the responsibility of flood storage by surrounding water systems. The ecosystem once collapsed and the water quality became inferior V class。

Before treatment:

As one of the largest artificial lakes in Guangzhou, Dongshan Lake not only plays the role of landscape, but also plays the role of flood regulation, storage and discharge, and sponge city。In recent years, the water quality of Dongshan Lake shows the trend of increasingly serious eutrophication and long-term inferior to the V class of surface water, in which the total phosphorus and total nitrogen exceed the standard seriously。The water was once green and smelly, and in the summer there was an outbreak of blue-green algae。

In view of the pollution status of Dongshan Lake and the importance of its location and function, a series of requirements are put forward for the treatment process: shorten the system construction period and reduce the impact of construction on the environment;Reduce the operating cost of investment;Ensure the long-term stability of water quality;Realize the sustainable development of ecological environment。These requirements are not small challenges to the coordination ability, industrial strength and technical strength of the project implementation unit。

Governance process:

Always follow the principle of "external control, internal reduction, treating both symptoms and root causes"。First of all, exogenous pollution, flood drainage and storage, and initial rainwater non-point source pollution have a great impact on the water quality of Dongshan Lake, and solving the pollution problem of exogenous pollutants in the state of rain overflow and circulation in the lake has become the key of this project。Secondly, Dongshan Lake Park has not been desilted for 15 years, and the pollutants in the sediment are constantly released to the water body, which is the main internal pollution of the water body.However, the park has a large flow of people, narrow roads, and the traditional dredging method has many problems, such as large operation area, serious impact on the environment, and difficult disposal of sediment。Therefore, Dongshan Lake sediment treatment using the advantages of simple construction, low cost, no secondary pollution and other in-situ reduction technology, through improving the sediment microenvironment, promote the decomposition of organic matter in the sediment, reduce the sediment, to solve the problem of internal pollution。

In order to purify the water quality of Dongshan Lake during water replenishment, quickly improve the water quality and increase transparency, the project also uses an integrated device of efficient coagulation microfiltration。The device integrates physical, chemical and microbial water treatment technology, and can design different unit sub-technologies by systematically analyzing the pollution characteristics and water quality characteristics of different regional water systems, water flow and different water quality requirements, and provide "menu" type technical support, which is efficient, flexible and practical。Compared with the traditional technology, it has the characteristics of low cost, small footprint, simple operation, flexible operation and high treatment efficiency, and can achieve the effect of rapid purification of water quality, elimination of black odor and improvement of various chemical indexes of water。

There are many factors involved in maintaining water quality。Take the control of species in a lake as an example，The most popular fish that swim into the lake from the Waijiang water body are tilapia, which like to burrow in the mud，Tilapia are very fertile，The impact on water quality is also very large;And when the lake is cleared of fish，The larval larvae of the larval mosquitoes in the lake were born in large numbers due to the loss of the natural enemies of fish，Affecting the surrounding environment of the lake。

In order to improve the water quality of Dongshan Lake in the short term，Project by planting pioneer submerged plants，Rapid recovery of aquatic plant community in Dongshan Lake，Then gradually restore the other communities of the water ecosystem，Together with aquatic plants, microorganisms, plankton, aquatic animals and other reasonable composition of water ecosystem，Restoring the original biodiversity of Dongshan Lake，To restore its structure and function to pre-contamination levels，Restore the ecological function and balance of Dongshan Lake，Finally, the good water restoration effect of clear water sense, complex community structure and beautiful ecological landscape can be achieved，Make Dongshan Lake into a virtuous cycle。At the same time, the carefully created water landscape, submerged vegetation and floating vegetation in the water body complement the existing greening of the park, and build an ecological park where man and nature live in harmony。

Governance results:

The project has been implemented since September 2017, and has been upgraded from Class V to Class IV water in 60 days.In 2019, the project was successfully accepted and has now entered the operation and maintenance period, and the water quality has reached the surface Class IV water standard stably。