LANZHOU, Oct. 3 (Xinhua) -- The once-polluted Leitan River in Lanzhou City, capital of northwest China's Gansu Province, has taken on a new appearance following the completion of a water treatment project in December 2020.

Today, sewage along the river, a tributary of China's Yellow River, is collected and transported to the main urban sewage network and discharged after meeting environmental standards.

"In 2021, our treatment capacity increased from 260,000 to 300,000 tonnes after an upgrade, which has helped improve the water quality of the Yellow River," said Zhang Lei from Yan'erwan wastewater treatment plant, where the sewage is treated.

Leitan River is no longer black and odorous today, thanks to the arduous wastewater treatment efforts. "The water quality of the mainstream of the Yellow River is continually improving," said Zhang Yali, an official with the Qilihe branch of Lanzhou ecology and environment bureau.

"In the second quarter of this year, the water quality at the Qilihe section of the Yellow River was graded Class I, which was rare in the past," Zhang added.

The transformation of the Leitan River is a reflection of the country's endeavors to protect the Yellow River, which is deemed China's "mother river."

China has set the ecological protection and high-quality development of the Yellow River basin as a major national strategy, and as a result, the river is expected to play a crucial role in striking a balance between environmental protection and economic growth.

The Yellow River originates from the Qinghai-Tibet Plateau and runs through the Loess Plateau. Flowing about 5,464 km through nine provincial-level regions, it is China's second-longest river, supplying water to 12 percent of China's population and irrigating 17 percent of the country's arable land.

For provinces and regions on the upper stream of the river, ecological protection is among their top priorities.

With the mainstream and more than 20 tributaries of the river running through Lanzhou, the city has endeavored to implement the national strategy.

As an old saying goes, "When the Yellow River is harnessed, China will enjoy the tranquility." Acknowledging that the tranquility of the Yellow River is essential to the country's stability, the Chinese people have fought Yellow River flooding since ancient times.

With a total investment of 1.68 billion yuan (about 237 million U.S. dollars), the city's embankment project was completed in 2021 after six years of construction. It is aimed at tackling the menace of flood and riverbank collapse, as well as strengthening environmental protection and afforestation.

"From 2018 to 2020, the upper reaches of the Yellow River experienced three consecutive years of high water, and the project has ensured the safety of the embankment," said Feng Kangbin, director of the Lanzhou water affairs department.

The city of Lanzhou, with heavy industries such as petrochemicals as its economic pillar, has accelerated its economic transformation to pursue lower resource consumption and greener economic development in recent years.

Strategic emerging industries such as biomedicine and high-end equipment manufacturing have become new drivers of the regional economy. In 2021, the added value of such industries in Lanzhou increased 46.5 percent year on year.

The green development path has also contributed to the joy of the people. Locals who enjoy jogging and outdoor leisure flock to the Yellow River banks in Lanzhou, thanks to the pleasant atmosphere.

"What was once a natural moat has become a river of happiness," said Yang Shiping, a speedboat driver with the Lanzhou water transport group, who has a witnessed the Yellow River's transformation over the past decades.