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The Yomiuri Shimbun Water mixed with paint, right, becomes clear as shown in the left beaker when a coagulant is added and stirred, in Ibusuki, Kagoshima Prefecture.
The Yomiuri Shimbun
10:46 JST, October 3, 2022
KAGOSHIMA — Southern Kyushu is covered in a soil called “shirasu,” which is composed of fragile volcanic ash that often gives way to landslides. Taking advantage of the characteristics of shirasu — specifically its high water permeability — Halvo Holdings Co. has developed a coagulant to improve water quality that it will use to help ensure a clean water supply in India.
The coagulant, which allows for water to be purified without large equipment, is easy to employ: one simply adds it to a tank and stirs the solution. The company has partnered with Save the Children Japan, an organization that supports children around the world, to provide drinking water to an elementary school in Delhi using the coagulant.
According to the company, groundwater in Delhi is contaminated mainly by industrial wastewater. Corporate representatives already visited Delhi in July to conduct a water quality survey. Thanks to the coagulant, the company will be able to provide about 220,000 liters of water per year, or enough for about 3,000 people, starting from next spring.
The coagulant is created by imparting an electric charge to shirasu, which has countless microscopic holes. It is already used to treat factory wastewater and purify rivers, as well as for international cooperation, such as the purification of water from the Mekong River in Vietnam.
