World Water Day | Unveil Dali Underground WWTP Project (IWA Project Innovation Awards)

World Water Day

March 22, 2023, is the 31st World Water Day and March 22-28 is the 36th Water Week of China. The theme for the 31st "World Water Day", March, 22, 2023, set by the UN, is "Accelerating Change." For our country, the theme for events for the World Water Day 2023, also the 36th Water Week of China is "Work jointly to protect our mother river through strengthening our law-based water governance. "

Erhai Lake is the mother lake of the Bai people in Dali. Tourists and the natives are here to enjoy the rippling seas and clear waters, and at the same time, pursue a poetry life and their dreams. However, Erhai was once faced with a decline in its water quality.

To protect this gift from nature, Dali decided to restore its ecology. On September 13, 2022, China Water Environment Group won the IWA Project Innovation Award (PIA) from the International Water Association (IWA) in Copenhagen, Denmark, with its self-developed Distributed Underground Reclaimed Water Ecosystem and its successful practice in the Dali project, becoming the only Chinese enterprise to receive this award.

Dr. Hou Feng, chairman of the CWEG, accepting the award

What do we know about this Dali project that won the PIA and how does it solve the water environment crisis? The answer lies in the DURWecosystem.

There are 6 underground WWTPs around Erhai Lake, like an artery forming to intercept and recycle domestic sewage. This project has spared 15% of the investment, saved 160 mu (approx. 10.7 ha.) of land, and shortened the construction period by 9 months. The plant was built underground to avoid the not-in-my-backyard problem. The water and land resources have been fully utilized and the water quality and ecology have been greatly improved. In 2021, the water quality of Erhai Lake reached Class II for 7 months, rated as excellent throughout the year. Ottelia acuminata, regarded as the touchstone of water quality, has been in full blossom again.

The book "A Step into Underground Water Reclamation Plants" provides a detailed introduction to the water environment management of Erhai Lake. Let’s take a look.

Water Environment Management of Erhai Lake Underground WWTP

1. Background

On January 20, 2015, General Secretary Xi Jinping took a photo with local officials by the Erhai Lake and said, "Let’s preserve this photo for verification. I believe that we will see a clearer Erhai Lake a few years later when we come back here.” Erhai Lake is the mother lake of the Bai people, the second largest plateau lake on the Yunnan-Guizhou Plateau, the core of the "Cangshan Erhai National Nature Reserve", and the main drinking water source of Dali.

It is a typical plateau lake with poor water mobility and ecological restoration ability. At the same time, wastewater from agriculture, aquaculture, and tourism was discharged into the Erhai Lake along the river, causing greater damage to the Erhai Lake.

2. Details

Six underground plants were built in Wase, Shuanglang, Shangguan, Wanqiao, Xizhou, and Dali Old City. Building an "artery" around the lake to intercept wastewater; saving 160 acres of land for tourism; synergizing water environment management and green development to alleviate financial pressure on the government; equipping the ecological pond with water facilities for water purification and agricultural irrigation.

The Dali Erhai Lake Underground WWTPs

The Shuanglang Reservoir with a capacity of 140,000 cubic meters

Dali Old City Underground WWTP

Dali Old City Underground WWTP

Dali Shangguan Underground WWTP

Dali Shuanglang Underground WWTP

Dali Wanqiao Underground WWTP

Dali Xizhou Underground WWTP

3. Achievements

The water quality and ecology of Erhai Lake have undergone fundamental changes. Statistics show that in 2017, the water quality was rated Class II for 6 months and Class III for the rest months as that of 2018 and 2019 Class II for 7 months and Class III for 5 months. There have been no large-scale blue-green algae, and the water quality is improving. Erhai Lake has also witnessed an increase in aquatic plants.

In October 2019, the documentary Beautiful China, co-produced by the Ministry of Ecology and Environment and China Media Group, was broadcast on CCTV 1. Taking the Erhai Lake project as an example, it demonstrates the remarkable achievements China has made in environmental protection and construction.

Harsha Ratnaweera (left), professor of Norwegian University of Life Sciences, Tom Mollenkopf, president of IWA, and Dr.Hou Feng (right), chairman of CWEG

“In terms of water environment management and resource utilization, the technological system and mode of innovation we adhere to are not only applicable to China but also to the whole world. I’m glad that what we have done is internationally recognized.”

—— Dr. Hou Feng, Chairman of CWEG

“The management of the Erhai Lake in Dali synergized the water environment and the social and economic development by giving full play to the water, which is of critical significance for the world’s water environment. He also believes that this meeting is a good opportunity for communication and the promotion of technological innovation in the field of water environment.”

——Tom Mollenkopf, President of IWA

“Represented by China Water Environment Group, Shanghai Jiaotong University, and Dali Prefecture, this major award mark a breakthrough for China in the world’s water science and technology. The wastewater interception mode in Erhai Lake has realized the integration and efficient utilization of water resources, green energy, and land resources, which is of leading significance for the world’s large lakes (larger than 200 square kilometers).”

—— Kong Hainan, director of the Erhai project, a national water pollution control and management technology major project