Constructed wetland improves water quality, flow of intensely polluted urban river

By Alex Card on November 25, 2014

If you don't remember the moral of Aesop's fable regarding the city mouse and his country-dwelling cousin, that's okay — neither does the rest of the human race. As of 2008, more than half of the world's population lives in an urban setting.

The population shift from rural to urban areas is changing the way people live, work and play, but it's also having an overwhelming impact on the environment. Massive metropolises such as New York City, Mumbai and Sao Paulo are locked in a constant struggle to manage the garbage, wastewater and particulate emissions from their millions of residents, while also supporting growth and industry.

The city of Suzhou in eastern China may not be as large as the aforementioned urban centers, but the Zhijiashe River flowing through the city's historic Luzhi Town region was incredibly polluted nonetheless. Waste from nearby homes and factories dumped directly into the river, bringing flow velocity to a near-standstill.

"Especially in the eastern and southern regions of China, many urban rivers are modified and polluted," said Haifeng Jia, director of the Center for Urban Runoff Control and Stream Restoration at Tsinghua University in Beijing. "Some urban rivers have become blocked, leading to very low or no water flow."

In an attempt to improve water quality and restore streamflow in the Zhijiashe, a team of researchers from Tsinghua University built a miniature wetland in the heart of Luzhi Town. The results of their work were published online in Ecological Engineering.