Total Reconstruction of an Urban Sewage Treatment Plant for Improving the Water Environment

This paper describes a project involving total reconstruction, within its current premises, of a sewage treatment plant that has been in operation for nearly 70 years in the center of metropolitan Nagoya.Nagoya is Japan's fourth largest city, with a population of approximately 2.2 million people. In the 1930s, before World War II, the municipal government commenced operation of four sewage treatment plants in the central part of the city, employing the activated sludge process. Since then the government has continued its efforts to improve public health and the water environment using these plants, but after about 70 years of operation they have begun to deteriorate.One of these plants, the Tsuyuhashi Sewage Treatment Plant, one of the oldest plants of its kind in Japan, is being reconstructed in this project. This treatment plant is located only 1.5 km south of the central part of Nagoya (Nagoya Station area) and adjoins a densely built residential area. Hence, it was difficult to prepare a new site for plant reconstruction, making it unavoidable to carry out reconstruction works within the existing plant premises.This project makes the most of a variety of technologies to carry out the reconstruction work without suspending the flow and treatment of wastewater generated in the urban area, as well as satisfies social demands for improved quality of effluent from the treatment plant and harmonious coexistence with the surrounding environment.