Ningbo Evening News | Ningbo, Zhejiang: First sunken reclaimed water plant trial operation

On March 20th, staff from China Water Environment Group's Jiangbei Submerged Reclaimed Water Plant were conducting equipment inspections on the underground inspection level. The reporter learned from the Ningbo Water Resources Bureau that the Jiangbei Submerged Reclaimed Water Plant has a processing capacity of 100000 cubic meters per day and is currently in trial operation.

Aerial photo of Jiangbei sunken reclaimed water plant above ground

Serving a population of nearly 300000

It is reported that this water plant is not only the first sunken reclaimed water plant in Ningbo City, but also the first reclaimed water plant developed in a coordinated manner above and below ground in China. Its service scope covers the Cicheng Town area, Sunhu area, Olympic Sports Investment Innovation area, Electromechanical Garden West area, Hongtangzhuangqiao West area, Tianshuizhuangqiao area, Airport area, Xiajiameiyan area and other areas in Jiangbei District, serving a population of nearly 300000. It will significantly improve the regional water purification capacity, improve the quality of water environment, lay the foundation for optimizing the recycling of water resources in Ningbo City, and promote the green and high-quality development of local economy.

As the reporter approached the project gate, Huang Jian, a senior engineer at Ningbo Water Environment Group, pointed to the above ground industrial park that was under construction and said, "Underneath these buildings is a two-story underground sunken reclaimed water plant. The total investment of the project is 1.193 billion yuan, and the civil construction scale is 150000 tons/day (equipment scale is 100000 tons/day). The project started construction in September 2020 and the main structure was capped at the end of June 2022. It has now entered trial operation

The person in charge of Ningbo Water Facilities Operation and Management Center stated that the operation of the factory has effectively solved the problem of long-distance cross regional transportation of sewage in Jiangbei District, greatly improving the water purification capacity of the Jiangbei Basin and the quality of the surrounding ecological environment. Compared to traditional water purification plants, sunken reclaimed water plants have the advantages of occupying less land, no noise, and no odor, making them environmentally friendly urban water purification plants.

Layered effect diagram of Jiangbei undergound reclaimed water plant

Many 'black technologies' underground

Huang Jianbian introduced and led the reporter into the underground processing plant area. Slowly descending the stairs, you will arrive at the basement level of the sunken factory area. The wide passage, combined with sunlight and lighting, makes this place bright and transparent, without any underground gloom or foul odor caused by sewage collection. Huang Jian walked into the sewage inlet area and saw a transparent house made of steel pipes and glass, with numerous equipment. He pointed to a large blue pipe above the roof and said, "When the sewage comes in, the odor it carries is all drawn into this collection pipe through a high-power exhaust fan, treated separately, and then released into the atmosphere through an exhaust tower after reaching the standard. So, you can't smell any odor in this factory area." Walking to the main passage, the blue square tube and silver fresh air pipe run parallel through the factory area. There is no other odor while collecting the foul odor and providing fresh air.

It is reported that since the construction of this underground reclaimed water plant began, all members of the project team have taken innovative measures, overcome difficulties, and made every effort to promote the progress of the project.

In the approval stage, due to the particularity of the project construction mode, with the joint efforts of the municipal and district approval departments, the project adopts an innovative approach of providing land separately above ground and underground, and approving planning conditions separately to ensure that the project starts ahead of schedule. In the design phase, BIM technology is introduced to transform 2D flat drawings into 3D visual models, enabling early detection and resolution of difficult to detect omissions in flat drawings, effectively improving design quality.

In the construction stage of deep foundation pits, the innovative design scheme of "double row cast-in-place piles+two opposite supports+wharf" was selected, which saved three months of construction time compared to the conventional design scheme, setting a new record for the scale and construction difficulty of foundation pits in the water industry in Ningbo.

Subsequently, under the guidance of Huang Jian, the reporter arrived at a window area and had a bird's-eye view of the basement basement level 2. He saw that 90% of the area was covered with buried water treatment structures, while the rest were crisscrossed with pipelines. Except for maintenance technicians, the underground second floor is generally not open to the public, "Huang Jian said.

Staff conduct equipment inspections

Increased local industrial development capacity

Walking out of the sunken factory area from the other end, the reporter found that the above ground office building of the water plant was integrated with the above ground industrial park, and it was completely impossible to see that it was a water plant. How much does the cost increase of such a complex ground and underground three story complex compared to traditional sewage treatment plants? How much value is created? Huang Jian calculated three accounts for the reporter.

One is the land value account. According to the proportion relationship of traditional water purification plants, such a factory area covers at least 100 acres. In addition to the protective isolation zone, the total land area should reach 400 acres. The sunken reclaimed water plant efficiently utilizes underground space by exchanging space for land area, reducing the land area by about 50% compared to conventional surface water plants. Moreover, all the above ground land can be used for secondary development and utilization, greatly enhancing the comprehensive land use value.

The second account is the ecological resource account. After treatment, the tail water can be used as recycled water to supplement the surrounding landscape, municipal water, and raw water for large industrial water supply. Compared to using tap water before, it saves at least 3 million yuan. In addition, the water plant is also designed with a water source heat pump, which will fully utilize the energy in the tailwater to meet the air conditioning needs of underground and above ground buildings. Compared with traditional air conditioning, it can save more than 50% energy.

The third account is the livelihood account. In the past, selecting a location for building a water purification plant in a city was a difficult problem. Residents hope to build supporting facilities, but they are also unwilling to build them in front of their own homes, which is known as the "neighborhood avoidance effect" in professional terms. Nowadays, the water purification plant is built under the industrial park, which not only eliminates odors and pollutants, but also increases the local industrial development capacity.

The person in charge of the Ningbo Water Facilities Operation and Management Center stated in an interview with reporters that according to the plan, the above ground part of the factory is planned to build a green, low-carbon and intelligent manufacturing industrial park integrating production and manufacturing, research and development, and business support. This will truly achieve efficient utilization of land resources, create a new model for water environment governance and land use, and is of great significance for improving the quality of our city's water environment, deepening the construction of Ningbo's ecological civilization, filling the environmental gaps in Jiangbei District, accelerating the construction of a national first-class ecological civilization demonstration zone and beautiful Ningbo.