Water Purification Experiment of Horikawa River, Nagoya - August 2002

Water Purification Experiment of Horikawa River, Nagoya - August 2002

The City of Nagoya, in cooperation with Chubu Electric Power Company, has begun a demonstration experiment aimed at improving the water quality of the Hori River that runs through the city. The Horikawa River has been a serious problem of deteriorating water quality due to urban wastewater, especially during the summer months, when foul odors and eutrophication have been pointed out. In this experiment, a method was adopted to improve water quality by increasing the amount of dissolved oxygen by pumping air-filled water into the riverbed.

In the experiment, a special device was used to generate 24 liters of air bubbles per minute to increase the amount of oxygen in the water, thereby promoting water circulation. Immediately after the start of the experiment, an increase in oxygen concentration was confirmed, and future surveys will collect detailed data on changes in water quality and the impact on the ecosystem.

The Horikawa River is a canal built in the early Edo period and is an important part of the historical landscape of Nagoya City. However, as urbanization has progressed, the inflow of domestic wastewater has increased and water quality has deteriorated. There have been attempts to improve water quality in the past, but fundamental improvements have not been achieved. This initiative is expected to serve as a model case for sustainable water quality improvement measures.

Related Information
In Nagoya City, a social experiment was conducted from March 2007 to March 2010 to introduce clean water from the Kiso River to improve the water quality of the Horikawa River. In this experiment, a water quality survey and verification of the purification effect were conducted in cooperation with a citizens' group, the "Horikawa 1,000 Person Survey Team. In addition, Nagoya City established a "Study Group on the Promotion of Horikawa Restoration" to examine the direction of measures to improve the water quality of the Horikawa and Shinhorikawa rivers.

Furthermore, the Nagoya Chamber of Commerce and Industry has formulated a "Vision for the Future of the Shin-Hori River," recommending the need to pursue water quality purification efforts in parallel with the development of towns along the river on the occasion of the Asian Games and the opening of the new linear railway line. These efforts are important steps toward improving the water quality of the Horikawa River and revitalizing the community, and citizens, government, and businesses must work together to create a sustainable environment.