Suzhou Creek cleanup sets model for polluted rivers

With the pollution of urban rivers increasingly becoming a global challenge, China's experience in the rehabilitation of the Suzhou Creek and sewage management offers key lessons to developing countries, according to a new book co-authored by UNHabitat and Tongji University.

According to the book, the achievement resulted from substantial investments in huge sewage treatment infrastructure construction and the building of large-scale water pollution control projects.

The book states that China has prioritized environmental protection in the national strategy under ecological civilization, aiming to promote sustainable development to the height of green development.

Most cities and towns in China have completed the planning of their drainage systems and have already built drainage systems and corresponding waste water treatment plants in the last 20 years.

Originally, the water quality of the 125-kilometer Suzhou Creek in Shanghai was clear. However, from 1914 to 1918, due to increase in population and acceleration in industrialization, domestic sewage and industrial waste water were discharged directly into the river, gradually polluting the water quality. By 1978, the entire river was polluted. The river's fish and shrimp were extinct by the 1980s.

The first step was implementation of a combined wastewater treatment project, which was put in operation in 1993. It collected domestic and industrial wastewater within the urban areas and transferred for treatment.

Per day, the system collected approximately 1.4 million cubic meters of sewage. The chemical oxygen demand of Suzhou Creek's main stream was reduced from 150 milligram per liter to 80 mg per liter.

Next, $1 billion was invested in the development of technologies to enhance the impacts of a sewage interception project. By the time the project was completed in 2002, the black and odorous phenomenon in dry weather was eliminated.

The next phases entailed 4.5 billion yuan ($670 million) devoted to elimination of the black odorous phenomenon occurring in wet weather and improvement of water quality. By 2008, the Suzhou Creek aquatic ecosystem had been restored.

According to Maimunah Sharif, executive director of UN-Habitat, the United Nations housing division, the rehabilitation story of Suzhou Creek is a good reference in global efforts to improve urban river environments.

Today, more than half of the world's 500 biggest rivers are seriously depleted or polluted. Wastewater effluents are major contributors to pollution of urban rivers and other surface water sources, threatening public health, environment and the blue economy, particularly in cities already experiencing water shortages, Sharif said.

The UN estimates that, on average, high-income countries treat about 70 percent of municipal and industrial wastewater they generate. That ratio drops to 38 percent in upper middle-income countries and to 28 percent in lower middle-income countries. In low-income countries, only 8 percent undergoes treatment of any kind.

"Increasing investments in wastewater collection and treatment to restore the health of heavily polluted urban rivers is, therefore, an urgent global priority," Sharif said.

edithmutethya@chinadaily.com.cn

(China Daily 03/15/2019 page12)