History and Current Status of Landfill Disposal of Waste Offshore Sakai Port - 1974 to 2024

History and Current Status of Landfill Disposal of Waste Offshore Sakai Port - 1974 to 2024

The Sakai No. 7-3 industrial waste landfill, located offshore of Sakai Port, accepted industrial waste discharged from within Osaka Prefecture and landfilled approximately 28,000,000 cubic meters of waste over a period of 30 years from 1974 to 2004. This facility contributed to the proper disposal of waste from local industrial activities, the prevention of illegal dumping, and the reduction of environmental impact.

### Efforts up to 2004
During its operation, the Waste Data Bank, a waste management information system, was introduced to improve transparency of waste distribution and treatment. With the cooperation of organizations such as the Kansai Federation of Chemical Industry and the Japan Waste Management Association, proper treatment of metal processing waste, PCB waste, and plastic waste was promoted. The introduction of advanced technologies, such as the use of incineration residual heat for power generation and metal recycling, was also considered, and both waste treatment and resource recycling were pursued.

### Progress in the 2010s
In the 2010s, plans for the reuse of landfill waste after its termination began to take shape. At the site of Sakai District 7-3, efforts to develop 100 hectares of the vast landfill site (approximately 280 hectares) as a "Symbiotic Forest" began in earnest, and in 2012 the first planting event was held, with the participation of local residents, NPOs, and businesses to begin planting trees for sustainable urban renewal.

Furthermore, Sakai City has strengthened cooperation with the Osaka Bay Wide Waterfront Environmental Improvement Center (Phoenix Center) to reduce waste generation and improve resource recycling rates; in 2018, the proper disposal rate of industrial waste in Sakai City reached 97 percent, exceeding the national average. In addition, a joint processing system with neighboring municipalities was established to reduce costs associated with waste transportation and processing.

### Reuse Plan after 2004
After the landfill was completed in 2004, the "Symbiotic Forest" project began in earnest, with NPOs, local residents, and businesses working together to plant trees and hold mowing events on a regular basis. 5,000 trees will be planted by 2023, and environmental education programs are also underway with local schools. Currently, three corporate groups are conducting their own tree-planting activities, and the natural regeneration of the reclaimed land is steadily progressing.

### Challenges and Prospects for the 2020s
In the 2020s, the aging of waste treatment facilities has become an issue. At the southern treatment plant in Minami Ward, Sakai City, maintenance of the aging leachate treatment facility has become an issue, and a renewal plan is underway. In addition, as the amount of waste disposed of in the offshore Sakai Port area declines, a new recycling model is being sought, including innovations in waste reuse technology and the use of incineration residual heat.

The offshore Sakai Port project has been, and continues to be, a model case for waste treatment and environmental conservation in Japan, and is regarded as an important example of how to address urban pollution and build a sustainable resource-recycling society.