Where did the sludge dissolve in the lake winds of Shiga in the late 2000s?

Where did the sludge dissolve in the lake winds of Shiga in the late 2000s?

In the late 2000s, Japan's sewage treatment industry was at a structural turning point. Many of the sewage treatment plants that had been built simultaneously throughout the country during Japan's period of rapid economic growth had become obsolete, and the cost of renewal was becoming a serious burden on local finances. The situation was further exacerbated by the declining population. While the amount of water used was decreasing and the volume of water treated was stagnating, the fixed cost of maintaining facilities was not decreasing. Inevitably, the trend was away from maintenance and management by a single municipality and toward the sharing of facilities and wide-area development.

The Kosai Sewage Treatment Center in Otsu City, Shiga Prefecture, was situated in the midst of this trend. The incineration and melting furnace, while fulfilling its role, had become obsolete and was in need of renewal. Otsu City's final sludge disposal plant was approaching the limit of its capacity, and it was becoming difficult to cope with the situation under the existing system. The two parties' circumstances complemented each other, and the prefecture and the city naturally chose to jointly dispose of the sludge.

Shiga Prefecture has a long history of water quality preservation in Lake Biwa. Many measures have been accumulated, including policies to prevent eutrophication, reduce domestic wastewater, and preserve the water environment of the entire watershed. Proper treatment of sewage sludge is an important element directly related to the foundation of these measures. Because Lake Biwa is a huge reservoir of water, the advancement of sludge treatment is not merely an administrative technology, but also an inevitable activity to protect the culture of life and the local environment.

According to a national survey at the time, around 25 million tons of sewage sludge was generated annually throughout Japan. Final disposal sites were seriously strained, and the reduction and recycling of sludge was a nationwide issue. Volume reduction by incineration and melting and reuse of molten slag had been attracting attention as a promising method to reduce the environmental burden, but the large amount of money required to update facilities was too much for local governments to bear on their own. Behind the progress of joint processing over a wide area were these two aspects of cost-effectiveness and environmental policy.

Shiga Prefecture was commissioned by Otsu City to handle the sludge treatment business, and the procedure was set to begin partial treatment first in FY2001. Furthermore, the prefecture will shift to a policy of accepting all of Otsu City's sludge after FY 2005, when the new furnace, which has been updated, will be in stable operation. This was not a radical reform, but a plan based on careful administrative buildup, including financial adjustment, capital investment, and organizational structure preparation.

Thus, a framework for joint treatment between Shiga Prefecture and Otsu City was formed at the intersection of aging facilities, a tight disposal site, and the region's unique mission to protect Lake Biwa. At the purification center, where the air of Kosai flows, a quiet change had begun to support the future of the region. Although the whereabouts of the sludge are not visible to the public, it has indeed become an important pillar in protecting the clear water of Lake Biwa and supporting the sustainability of the region.