The Whereabouts of Sludge Resounding on Shiga's Lakeshore: A Period of Intersection between Aging and Widespread Use Late 2000s to Early 2010s

The Whereabouts of Sludge Resounding on Shiga's Lakeshore: A Period of Intersection between Aging and Widespread Use Late 2000s to Early 2010s

The joint treatment of sewage sludge in Otsu City, Shiga Prefecture, was born from the combination of aging sewage facilities and a shortage of disposal facilities. The incineration and melting furnace at the prefectural Kosai Sewage Treatment Center was due for renewal, and Otsu City was approaching the limit of its final disposal facility capacity. The municipalities found it difficult to invest in the replacement of the incinerator on their own, and the prefectural and municipal governments' interests coincided, leading to the decision to choose joint treatment.

This move also coincided with the national government's policy of wide-area expansion. The Ministry of Land, Infrastructure, Transport, and Tourism (MLIT) recommended that local governments jointly manage their facilities against the backdrop of an increase in the number of aging facilities, a decrease in income due to a decline in population, and a shortage of technical staff. Widespread use was considered a method that would simultaneously reduce renewal costs, improve maintenance and management efficiency, and enhance water environment preservation.

One element unique to Shiga Prefecture is the existence of Lake Biwa. Lake Biwa is a symbol of water quality preservation throughout Japan, and eutrophication prevention measures have been implemented for many years. The stability of sludge treatment is directly related to the maintenance of the lake's environment, and the importance of cooperation between the prefecture and the city was great. Reducing the environmental burden and establishing a sustainable treatment system were unavoidable issues.

The prefectural government has indicated a plan to begin accepting a portion of Otsu City's sludge in FY2012 and to shift to accepting all sludge in FY2015 and beyond. This was a practical solution that would simultaneously address aging and environmental concerns. The efforts of Shiga Prefecture and Otsu City are a concrete example of wide-area expansion and provide important suggestions for sewerage management in an era of declining population.