Abstract
To apply the Japanese johkasou to overseas countries, it is necessary to discover the design method that allows the redesign of the Japanese johkasou to meet various operational conditions. In this study, focusing on the differences in performance evaluation method between Japan and EU – wastewater volume and pollutant loads, an EU-oriented facility was designed with equal BOD volumetric load to the prototypical Japanese model, and was installed and experimented in the EU region. Meanwhile, the Japanese model was tested in Japan. The test results were then comparatively analyzed. As a result, BOD and SS in effluent in the EU test were at the same level with the Japanese model, and no influence of short-term inflow load fluctuations on effluent quality was observed. Moreover, the analysis of the influence of water temperature on treatment performance shows that the design method using BOD volumetric load and considering the influence of water temperature on the nitrification rate is effective for adaption of johkasou to overseas countries. Furthermore, it is suggested that keeping water temperature in the facility over 13 °C is important for constant removal of nitrogen and BOD.
