EVALUATION AND PRACTICAL APPLICATION OF INNOVATIVE WASTEWATER TREATMENT TECHNOLOGIES IN THE AGE OF DECLINING POPULATION

<p> Although the revenue from sewerage charge is expected to decrease, especially in small municipalities because of the decline in population, they are obliged to decrease the emission of greenhouse gases. To address these problems, the Japanese government supports the development of innovative technologies that will reduce costs and energy consumption in wastewater treatment plants. However, the developed technologies for small-scale treatment plants have not yet been widely used. This study aimed to evaluate innovative technologies with multiple indicators, and clarify the obstacles to the introduction of those technologies through the analysis of sewerage statistics, sewerage management plans and interviews with related parties. It was found that those technologies have high potentials to save energy and cost; however, it was difficult to compare the efficiencies among them. Additionally, because small-scale treatment plants have not yet been due for renewal, they tend to postpone the installation of new technologies. Furthermore, the result of stakeholder analysis has revealed that there is a structural problem of discrepancy in the needs and different incentives for new technologies among the stakeholders, namely, the national government, municipalities, companies, and residents. Therefore, to promote the practical application of new wastewater treatment technologies, it is important to develop and support the introduction of technologies that can achieve national objectives and fulfill the needs of residents and municipalities concurrently, and to delineate their benefits to the residents and municipalities.</p>