Japanese Experiment Launched to Purify Dirty River Water Using "Garden Rafts" and Aeration

Copyright Yamagata Prefecture

The prefecture of Yamagata in northern Japan began an experiment on September 15, 2009, with the aim of improving the water quality of the Numa River, which runs through the city of Sagae, with support from local corporations and citizens. The experiment is being conducted to verify the effectiveness of two combined water purification methods: direct aeration of river water and floating "garden rafts" loaded with aquatic plants.

The Numa is a five-kilometer-long, first-class river, which runs east to west through Sagae before flowing into the Mogami River. It has the dubious honor, however, of being named the second dirtiest river in the prefecture, making it an urgent issue to improve its water quality.

In the experiment, bamboo rafts, each measuring 1.8-meters long by 1.5-meters wide and planted with watercress and swamp morning-glory (Ipomoea aquatic), were launched on the river. An aeration device was placed in the center of the river to directly aerate the water by pumping air through a one-meter tube to increase the level of dissolved oxygen. Water quality will be regularly checked both upstream and downstream of the garden rafts to assess the effects of purification efforts.

The prefectural government hopes that the participation of citizens will increase public awareness of the water quality and environment of the river, and it intends to hold hands-on activities and seminars on environmental conservation so that citizens and companies in Sagae can join in other green activities to protect the Numa River.

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Posted: 2010/03/04 06:00:15 AM