Subterranean sewage plants result in environmental improvements

The park south of the Nanming River in Guiyang, capital of Guizhou province, looks no different from many others on a clear, crisp morning as the birds sing and runners and walkers exercise.

Hou Jinzhi, who takes a walk in the park every morning, carrying his pet bird in a cage, said, "If you don't live locally, you would never know there is an underground sewage treatment plant here."

The 76-year-old was among residents who initially opposed the plant being built due to environmental concerns, but he quickly found that the facility had no impact on the area.

Apart from a low droning sound coming from near two air outlets for the plant, he said no other noise can be heard from the facility. Neither can any foul smells be detected.

Completed in 2015, the Qingshan ("lush mountain") plant is the first underground sewage treatment plant in Guiyang, and it may provide a solution to the increasing amount of sewage in urban areas with shrinking land resources.

Zhou Fubo, head of the plant, said that instead of troubling residents with noise and bad smells, the plant can greatly benefit the neighborhood.

Stretching for about 185 kilometers, the Nanming River used to be so clear that residents took water directly from it for drinking. However, years of industrialization and urbanization in Guiyang left the waterway heavily polluted and killed most of its aquatic life, according to the city's water resources management bureau.

Thanks to the local government's pollution control efforts around the turn of the century, by 2004, the river water had become significantly cleaner, but the situation worsened again as Guiyang's population doubled to 4 million from 2004 to 2012.

Hou was keenly aware of the worsening pollution in the river.

"When I was a child, I often swam in the river. The water was so clear that you could see the bottom," he said.

When the river became heavily polluted due to industrialization in Guiyang, Hou avoided it as much as possible because of the overpowering stench that came from the waterway.

Campaign launched

Liu Chuxia, deputy head of Guiyang's water resources management bureau, said the turning point came in 2012, when the Guiyang government launched a campaign to eliminate pollution in the river.

She said waste water used to be collected and sent for disposal via a network of pipes to a sewage treatment plant far downstream from Guiyang, but there were huge difficulties not only in building the network but also in maintaining it.

There were frequent leaks from the pipes in the city, which has a karst landform, she added.

Liu said that when the campaign was launched, the Guiyang government decided to innovate by building disposal facilities and recycling reclaimed water near sewage sources.

After 2017, another 14 such underground facilities were built in the city, according to the local authorities.

Liu said Guiyang was the first Chinese city to use "distributed facilities" to dispose of sewage.

The water quality in some urban stretches of the river used to be below Grade V, the lowest level of the national five-tier grading system for surface water, she said.

Thanks to the new facilities, the city has cleared all 25 black and odorous bodies of water on the river and the water quality on some urban stretches has reached Grade III. "The river's self-purification capacity has gradually been restored," Liu said.

Every day, 1.5 million metric tons of reclaimed water is discharged into the river from the sewage plants, greatly easing water depletion that jeopardizes the aquatic ecosystem.

In addition to an improved environment for local residents, the mode of sewage disposal, which is cost-efficient and saves land resource, has enabled the local government to tap more business opportunities in the Nanming River Basin.

For example, the 14 underground plants built after the Qingshan facility led to savings of 1.5 billion yuan ($232.5 million) in building a sewage pipe network and acquiring land. If they had not been built underground, these plants would have occupied about 11 hectares of land, Liu said.

"This mode helps resolve the difficulties mountainous cities have in finding land to build sewage disposal facilities," she added.

Economic benefits

Much of the space saved has been used to build parks and other leisure facilities that meet residents' demands for recreation. Construction of some underground plants has been incorporated into the development of commercial complexes, resulting in significant economic benefits.

For example, commercial buildings, office blocks and sports facilities occupying a total area of 249,700 square meters, as well as parking lots that can accommodate more than 4,000 vehicles, stand above two of the plants built 30 meters underground, Liu said.

Hou Feng, president of China Water Environment, which is based in Beijing, said the company's mode of operation in Guiyang has won widespread recognition.

This mode has been used on Erhai Lake, Yunnan province, in Chengdu, capital of Sichuan province, and also in Beijing, Hou Feng said.

Following the environmental improvements, tourism has boomed in Nanming district, one of the central districts of Guiyang.

For example, locations near the Jiaxiu Pavilion, a landmark ancient building by the river, are often packed with tourists until late at night in summer.

Li Na, administration manager at the Xiyuan teahouse near the pavilion, said she has seen increasing numbers of tourists in the area since the environmental improvements were made.

The area is always busy during the peak summer tourism season, with most shops full of customers, she said, adding that many people choose to stay in her teahouse all afternoon to enjoy the pleasant riverside environment.

Yin Kaiyun, who has run the Huayuan barbecue restaurant near the pavilion for seven years, said, "Since July, we've often been busy until after midnight."

The 47-year-old's business has only 30 tables, each catering to about 10 groups of customers a day. People often wait about an hour for a vacant table, Yin said.

He added that about one-third of his customers are tourists from outside Guizhou, seeking relief from the summer heat.

According to the Nanming district administration of tourism, thanks to the environmental improvements on the Nanming River, construction of leisure facilities, along with commercial development, the number of tourists to the district soared from about 6.4 million in 2012 to 24.3 million last year.

The district's tourism revenue, which has risen on average by 15.6 percent a year since 2012, reached 56.1 billion yuan last year, despite the impact of the COVID-19 pandemic.

Wang Yaojun, deputy head of the administration, said: "Many scenic spots near the Nanming River have become highly popular tourist destinations. The campaign to clean up the waterway has produced immeasurable results."

Hou Jinzhi, the senior who lives near the Qingshan sewage disposal plant, said: "The Nanming River has now returned to how it was in my childhood. The environmental improvements make me feel very happy."

Zhao Yandi contributed to this story.