China News Service, Wuxi, June 20 (Reporter Sun Quan) "After the sludge at the bottom of the lake is dehydrated and solidified, it can be used as a raw material for landscaping, and can also be made into ecological and environmentally friendly building materials. To meet the standard and flow into the inland river, you can achieve multiple goals with one stone." On the 20th, in the emergency dredging project department of Wuxi Meiliang Lake (Dushankou), project manager Yuan Kunkun told reporters from Chinanews.com the whole process of "turning waste into treasure" at the bottom of Taihu Lake. process.
The mud is pumped out through a closed pipeline.
Photo by Sun Quan
Taihu Lake sediment is rich in nitrogen, phosphorus and other substances, which is the main internal pollution source.
Removing the surface sediment at the bottom of the lake can greatly reduce the endogenous pollution of the lake, inhibit the impact of the release of pollutants in the sediment on the water environment, and create conditions for the restoration of the aquatic ecosystem.
Sludge solidification equipment of the project department.
Photo by Sun Quan
As one of the most critical frontier positions and main battlefields for Taihu Lake governance, since 2007, Wuxi has completed a total of about 30 million cubic meters of ecological dredging in Taihu Lake, salvaged about 18.5 million tons of blue-green algae, and diverted about 750 million cubic meters of water from the Yangtze River into Taihu Lake every year. In 2021, the water quality of the 26 main rivers entering the lake will all reach or be better than Class III, the water quality of Taihu Wuxi waters will be the best in the past 10 years, and the high quality will achieve safe summer for 14 consecutive years.
After the sludge is solidified, mud cake and tail water are produced.
Photo by Sun Quan
Statistics show that in the 13 years from 2007 to 2020, Wuxi has completed the first phase of the Taihu Lake ecological dredging project, the first phase, the second phase and the second round of the first phase, with a total of 23 million cubic meters of dredging, accounting for the same period of environmental protection. 70% of the total amount of dredging in cities around Taihu Lake.
Sludge solidification equipment is lined up.
Photo by Sun Quan
"At the end of May this year, we launched the second round of the Taihu Lake ecological dredging project, the purpose of which is to further consolidate the effectiveness of the comprehensive management of the Taihu Lake water environment." The relevant person in charge of the Wuxi Water Conservancy Bureau said that during the "14th Five-Year Plan" period, Wuxi will implement plumbing measures. The ecological dredging project in Lianghu, Gonghu, Zhushan Lake and the west coast of Taihu Lake covers an area of about 80 square kilometers, with a dredging volume of about 18.04 million cubic meters and a total investment of about 3.6 billion yuan.
The resulting mud cakes can be used as raw materials for landscaping, and can also be made into eco-friendly building materials.
Photo by Sun Quan
According to the arrangement, in 2022, Wuxi plans to dredging the total scale of about 3.47 million cubic meters.
Among them, the dredging scale of Meiliang Lake (Dushankou) area is about 220,000 cubic meters, the dredging scale of the west side of Meiliang Lake Xiaowanli Waterworks and Yueliangwan area is about 2 million cubic meters, and the dredging scale of Yixing Taihu West Coast area is about 125 million cubic meters. Wanfang, with a total investment of about 694 million yuan.
Compared with previous dredging projects, this round of dredging projects in Wuxi not only has a huge volume, but also changes in the dredging process and sludge treatment.
Bricks made of mud cakes, unburned ceramsite.
Photo by Sun Quan
Taking the emergency dredging project of Meiliang Lake (Dushankou) as an example, the project department currently has 8 sets of silt solidification equipment, which can process about 4,800 cubic meters of silt every day, and can form about 1,600 cubic meters of mud cake.
"After these mud cakes are deeply processed, they form the bricks and unburned ceramsites that you see now." Yuan Kunkun said that the project department is working on adding 8 more silt solidification equipment, in order to speed up the "turning of waste into waste" at the bottom of the lake. Treasure" speed.
After the tail water enters the ecological purification pond (canal), it can be directly discharged to the inland river after treatment.
Photo by Sun Quan
In terms of tail water treatment, the tail water generated by sludge solidification is first balanced in the tail water conditioning tank, and then the activated sludge and contact oxidation are combined for dephosphorization and nitrogen removal treatment in the biochemical tank, and the system effluent is filtered through the filter dam After the water quality reduces suspended solids, it enters the ecological purification tank (canal), and then uses aquatic plants to further absorb ammonia nitrogen, nitrate nitrogen and soluble phosphate in the water body, and synthesize its own protein, DNA and other substances, which can significantly improve the transparency of the water body and play a certain role. Water conservation.
Desilting in Taihu Lake creates conditions for the restoration of aquatic ecosystems.
Photo by Sun Quan
"The purified tail water that everyone sees now is very clear and can meet the standard of Class IV water. This water is discharged into the inland river first, and then flows into Taihu Lake." Yuan Kunkun said.
It is reported that in order to promote the continuous improvement of the water environment of Taihu Lake and ensure the higher quality of Taihu Lake to achieve "two guarantees", Wuxi has decided to implement 189 key projects of Taihu governance this year, involving drinking water safety, comprehensive river channel improvement, construction of beautiful rivers and lakes, cyanobacteria There are 9 major categories including lake emergency prevention and control, key water conservancy projects, industrial and agricultural domestic pollution control, and ecological restoration. The annual planned investment is 10.1 billion yuan, which is 2.6 times the investment in 2021.
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