China's pollution-fighting farm
An innovative project uses a hydroponic vegetable farm to clean up China's Dianchi Lake.
Story by Mary Kay Magistad, PRI's The World. Listen to audio above for full report.
China has some of the world's worst water pollution. And the country's farms are responsible for a big part of that problem. So there is a certain irony in visiting a farm here that purports to actually help reduce pollution from other sources. But that's the claim of a 100-acre hydroponic farm in China's southwest.
The farm on the edge of Dianchi lake grows some 30 types of vegetables, including long green rows of lettuce and spinach that sway in the wind and float on platforms with their roots in the water.
Where other farms would need fertilizer to provide nutrients for their crops, the vegetables here get their nutrients from sewage that's been dumped in the water by the city of Kunming and its environs. Sales representative Cao Jiangrui said that's all the fertilizer they need. She said government inspections to prove the vegetables are safe to eat, and that by putting the nutrients to use, the pilot project helps -- in a small way -- to clean up Dianchi lake.
Dianchi is a sprawling, shallow lake, about 25 miles long and 5 miles wide. It was once a source of drinking water for the city of Kunming, but that was before China's economic boom took off and the flow of pollution into the lake exploded, causing the water near the shore to become a stinking, foaming green-and-black swirl.
Today, the stench is gone, and the water looks more normal, if still far from clear. Most of the change has come from new policies by the local government, which has shut down polluting factories, ordered idle sewage treatment plants to restart, and is more closely monitoring pollutants like sewage and pesticides. Observers here say the hydroponic farm is another promising approach.
Chemical engineer Jiang Li Hong of the Kunming University of Science and Technology monitors water quality for the project. She said the improvement in the quality of water that flows through the farm is dramatic -- the vegetables remove 95 percent of the ammonia, and up to 60 percent of the phosphorus and nitrogen, which can choke the oxygen out of the lake but are just what the vegetables need.
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