China Environmental News | Underground Reclaimed Water Plant Grows and Roots by the Nanming River

Comparison chart of influent, purified water, and effluent of Qingshan Reclaimed Water Plant. Photo by Wang Yuning

"Look! After being treated by the recycled water plant, the water flows back into the Nanming River from here." Standing on the boardwalk in the park, Hao Wenlei, Deputy Director of Qingshan Recycling Water Plant in Guiyang City, Guizhou Province, pointed to the front outlet and explained. On the banks of the Nanming River, this scenic park adjacent to the river has a pleasant scenery. In the park, the pavilion is quiet, the benches are comfortable, table tennis enthusiasts are engaged in fierce battles, and the basketball court is also bustling. This place has complete facilities and is an ideal place for nearby residents to relax, take walks, and exercise.

What is the connection between the park and the recycled water plant? The mystery lies underground in this park - a fully sunken Qingshan recycled water plant quietly sits. Why should the recycled water plant designed, constructed, and operated by China Water Environment Group be built underground? What are the advantages of underground recycled water plants? Our reporter went to Qingshan Reclaimed Water Plant to find the answer.

From "turning black and smelling" to "almost identical to pure water"

"Since the 1990s, with economic development and population growth, problems such as garbage accumulation, domestic sewage, and corporate pollution have become increasingly prominent, continuously breaking through the ecological environment capacity of the Nanming River, causing water quality deterioration, severe black and odor, ecological extinction, and becoming a 'lifeless river'." Hao Wenlei pointed to the comparison chart of Nanming River governance and explained. In the figure, the differences between some key sections of the Nanming River in 2013 and 2022 are clearly visible. Before the treatment, the Nanming River turned black and there were many floating debris on the river, which was extremely polluted.

As the mother river of Guiyang and an important tributary of the Wujiang River, the health status of the Nanming River is related to the ecological balance and sustainable development of the entire Guiyang city and even the Wujiang River basin. Solving its pollution problem is urgent.

In November 2012, Guiyang City launched a systematic and new management of the water environment in the Nanming River Basin. "The governance of Nanming River is divided into three stages: the first stage is' emergency ', the second stage is' root cause', and the third stage is' system improvement '. The Qingshan Reclaimed Water Plant is a sewage treatment facility built during the' root cause 'period to improve water quality." Hao Wenlei said. In 2014, the Qingshan Reclaimed Water Plant was completed and put into operation, with a sewage treatment capacity of 50000 tons/day, a service area of approximately 10.86 square kilometers, and a total population of approximately 267000 people.

The construction of a recycled water plant underground has multiple advantages. "Building on the ground requires an area of 76 acres, while the sunken Qingshan Reclaimed Water Plant only occupies 32 acres." Hao Wenlei said, "Moreover, underground construction enables the water plant to achieve 'zero distance' from residential areas, saving an additional 500-900 acres of sanitary protection distance land."

As the distance approaches, will residents be troubled by the odor and noise from the water plant? Hao Wenlei said, "Our water treatment units adopt a fully enclosed design and use advanced bio composite deodorization technology to ensure that the odor emissions in the factory area meet the first level standard. As all equipment is located underground, it greatly reduces mechanical noise and vibration, and has almost no impact on ground buildings and residents' lives. In fact, after the completion of the Qingshan Reclaimed Water Plant, the surrounding commercial districts gradually emerged, which also drove up the surrounding housing prices."

There is a cup on the table next to the water outlet in the water plant, and the yellowish liquid inside attracts the attention of the reporter. "This is a sample of the sewage that came into the factory today." Then, Hao Wenlei twisted open a new bottle of pure water and poured it into another cup. At the same time, the staff of the water plant scooped up a cup of freshly treated water from the outlet and placed it side by side with the first two cups. The reporter found that the treated water has undergone significant changes compared to the untreated sewage, and it is almost pure water in terms of sensory perception. "The main indicators of the effluent from Qingshan Reclaimed Water Plant have consistently reached surface level IV, making it the first fully submerged reclaimed water plant in China to achieve such high-quality effluent without the use of membrane technology," said Hao Wenlei proudly.

From underground to above ground, from Building 1 to Building 16

Where did the treated water go? The reporter learned that the recycling rate of the tail water from the Qingshan Reclaimed Water Plant has reached 100%, mainly used for the ecological landscape of the Nanming River, the surface active water landscape park, the construction of surrounding communities, municipal road watering, green maintenance, etc. It can also serve as green energy to provide centralized heating and cooling services for the ground office building.

On the ground level of the Qingshan Reclaimed Water Plant, there is a Guiyang Water Environment Science Popularization Hall that is open to the public for free. The venue utilizes innovative, visual, and three-dimensional technological means to showcase Guiyang's water culture, water resource situation, and cutting-edge water resource management and protection concepts to visitors. Every year, a large number of primary and secondary school students come to study, and through practical experience, they deeply understand the importance of water conservation.

"The students really enjoy the experience activities of simulating the water ecological environment observation area. Through VR glasses, the scene of blue waves rippling and birds playing on the sand table is vividly seen," said Huang Qi, a lecturer at the Guiyang Water Environment Science Popularization Museum. "In fact, these VR devices were equipped when we built the museum in 2016. After years of management and protection, the river section outside the museum has become clear and green, and such beautiful scenery no longer needs to be presented through virtual technology."

The Qingshan Reclaimed Water Plant is the first fully submerged reclaimed water plant in Guizhou Province, and it is also a microcosm of the environmental management of the Nanming River. Starting from "Qingshan", the treatment of sewage in Guiyang city has shifted from traditional "large-scale concentration and interception" to organic combination of "distributed planning" and "sinking type recycled water system", forming a distributed sinking recycled water ecosystem.

In 2017, the 7th Central Environmental Protection Inspection Group pointed out that "approximately 400000 tons of domestic sewage are discharged directly into Guiyang City every day, causing pollution to the water quality of rivers such as the Nanming River.".

With the continuous improvement of the local government, water plants have taken root on the banks of the Nanming River. As of now, there are 34 recycled water plants in the Nanming River Basin, including 16 sinking sewage treatment plants.

This ecosystem not only cleverly solves the problems of heavy odor, high noise, and insufficient protection distance in traditional ground sewage treatment plants, but also saves about 1.5 billion yuan in pipeline construction and land acquisition investment, and saves 163.5 acres of construction land. Every year, high-quality tail water can also provide ecological replenishment of 450 million tons for the Nanming River, effectively solving the problem of insufficient ecological base flow in the Nanming River.

The ground of the reclaimed water plant is planned and constructed according to the plot, including ecological parks, sports venues, BRT hub stations, commercial complexes, and public utility buildings, achieving an organic combination of efficient land use, environmental governance, and resource utilization.

On the banks of the Nanming River, the underground recycled water plant saves money and land, efficiently utilizes the above ground space, and opens up an innovative path for sewage treatment that allows clean water to flow for a long time.