With the promotion of the concept of "Beautiful China", in order to improve the current situation of water environment and optimize people's living environment, governments at all levels have paid more and more attention to the livelihood of urban sewage recycling in recent years. Underground reclaimed water treatment plants use underground space scientifically and reasonably, and only account for one third of the traditional overground sewage treatment plants under the same treatment capacity. Therefore, underground reclaimed water treatment plants will become a new concept and development trend in areas with prosperous economy, high land resources and high environmental requirements.

Development of underground reclaimed water plant

With the continuous development of economy and the constant promotion of urbanization construction, China is facing the challenges of water environment problems such as sewage addition and water shortage, as well as the lack of land resources and the rational layout of urban infrastructure. How to balance the contradiction between the renewable use of urban sewage resources and the lack of land resources has become a difficult problem faced by many large and medium-sized cities and development zones in China.

The rise of underground reclaimed water plants has enabled the concept of sewage treatment plants in urban central areas to be developed. However, due to the restriction of traditional technology, underground treatment is very difficult. Through constant technological innovation, the MBR technology has enabled us to achieve this goal. The successful practice of this technology in underground reclaimed water plants has opened up new trends in sewage management, water shortage and urban land saving in large and medium-sized cities.

In the world, the construction of underground reclaimed water treatment plants started earlier, such as the United States, Britain, Japan, South Korea, Sweden and other prosperous countries, underground reclaimed water treatment plants have achieved tremendous economic and social benefits. It is understood that about 50% of South Korea's sewage treatment plants are built underground, and most of Sweden's sewage treatment plants are also built underground.

Advantages of Underground Reclaimed Water Plant

Underground reclaimed water treatment plant breaks through the traditional concept of wastewater treatment plant land use, scientific and rational use of underground space, in the case of the same treatment ability, only 1/3 of the traditional overground wastewater treatment plant.

Underground reclaimed water plant is built in the central city, not only a lot of sewage collection, pipeline network transportation capital and operating costs, together with the avoidance of leakage pollution caused by pipeline network transportation, purified reclaimed water can also be used in situ, reduce the investment of the water network, has a significant social, environmental and operational costs. Economic benefits can be said to have achieved the win-win effect of economic friendship and environmental friendship.

Its surface can be beautified, such as wetland ecological park or forest park, adding the beautification rate of the surrounding environment. The use of deodorization and noise reduction skills throughout the plant can effectively eliminate the noise of sewage plants and the impact of odor on the surrounding residents, which not only beautifies the surrounding environment, improves the value of land, but also broadens the space for urban development.

MBR as a preemptive technological skill is the main selection of underground reclaimed water plants

Underground reclaimed water plant has the characteristics of disorderly technology and difficult construction, which is the highly crystallization of innovative sewage treatment skills. Its core treatment skill is membrane bioreactor (MBR), which adopts integrated and intensive planning concept, has the function of enhancing nitrogen and phosphorus removal and reducing emissions far beyond the traditional process. It is an advanced wastewater resource technology in the world. The sludge output value of MBR process is about 1/2 of the traditional process, which can reduce the occurrence of sludge from the source and reduce the amount of sludge. The cost of sludge disposal reduces the secondary pollution, and the whole construction can complete the automatic control of the whole process from water intake to water outlet. The protection is simple and the human capital is reduced usefully. In addition, the effluent treated by this process is superior to the high-quality reclaimed water of Class IV of surface water in the national level A discharge standard, and the effluent quality is very stable.

Kunming 10th Sewage Treatment Plant Project launched in July 2011 is the main project in the 12th Five-Year Plan of Dianchi Lake Management. It was built by Dianchi Investment Company and Bishui Water Company in the form of BT. The successful cooperation between the two sides explored a new way for introducing social funds, advanced skills and Dianchi Lake Management. In July 2013, Kunming Municipal Committee and Municipal Government held the commissioning ceremony of Kunshi Waterworks, completed the huge project of underground sewage treatment and beautification of the ground scene. The sewage treatment plant has a treatment plan of 150,000 m3/d, a service area of 20.45 km2 and a service population of 430,000. It is now a relatively large and advanced reclaimed water treatment plant in the whole country. It is also the first underground reclaimed water plant put into operation in the Southwest Cooperative Region. It can be regarded as a model.

Underground reclaimed water plants will play an important role in the process of urbanization in China, and some domestic enterprises have taken the lead in this field.

In recent years, China has allowed the construction of several groundwater treatment plants. In Beijing, Shenzhen, Qingdao, Yantai, Kunming, Hefei, Gusu, Xiamen, Guilin, Taipei and other regions, projects of groundwater treatment plants have been launched continuously. In terms of project construction, Beijing Bishui Science and Technology Co., Ltd. is ahead in this field. The company has successively built 10 factories in Kunming (150,000 tons/day, underground MBR), 9 factories in Kunming (100,000 tons/day, underground MBR), Yantai Taoziwan (150,000 tons/day, underground MBR), Shijiazhuang New Area (100,000 tons/day, underground MBR) and so on. Influential projects have accumulated sophisticated and rich experience in the construction of underground reclaimed water plants.

Industry experts say that the core MBR skills of underground reclaimed water plants are now appropriately sophisticated. Its tonnage of water is 0.26m2, and the investment of wastewater in the first class of projects is between 4000 and 5000 yuan/ton. The direct operating cost of the projects can be controlled between 0.6 and 0.8 yuan/ton.