Development of new ultrafiltration techniques maintaining in-situ hydrochemical conditions for colloidal study

Aosai, Daisuke; Yamamoto, Yuhei; Mizuno, Takashi   

Size distribution of elements in groundwater is one of the most important information for understanding behavior of elements in deep underground environment. Size distribution is controlled mainly by groundwater physico-chemical parameters. Because the alteration of their physico-chemical states in groundwater cause changes of size distribution, systematic methodologies of ultrafiltration maintaining in-situ pressurized and anaerobic conditions is required. In this study, instrument for ultrafiltration maintaining in-situ pressurized/anaerobic conditions was developed and size distribution analysis was also conducted. The instrument developed in this study for consisted of passivated SUS materials is designed as to keep inner groundwater sample under a pressurized/anaerobic condition. Ultrafiltration was conducted at a borehole drilled from sub-stage at a depth of 200 m at the Mizunami Underground Research Laboratory site. The results obtained here indicate that ultrafiltration method is available for collection of filtered groundwater and passivation is an essential treatment before ultrafiltration.