| Research Abstract |
This research aims to investigate behavior of fluorinated POPs (persistent organic pollutants), such as PFOS (perfluorooctane sulfonate) and PFOA (perfluorooctanoate, in urban water environment, and to study their countermeasures. The following results are drawn from three years research work:
(1) Analytical procedure development
In addition to PFOS and PFOA, a measurement procedure of other several PFCs (perfiuorinated compounds) was also investigated. This work included extraction of PFCs from particulate phase and condition optimization of SPE (solid phase extraction) and LC-MS/MS.
(2) PFCs distribution surveys in Japan and overseas countries
Water samples from natural areas (rivers, lakes and others), tap water, and discharge from wastewater treatment plants were collected at several sites in 14 prefectures (Japan), and 10 overseas countries. PFCs analysis of these samples shows (1) PFCs level are different in earl prefecture and country, (2) Sources of them are non-natural, especially
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from wastewater treatment plants, and (3) Their concentrations are not reduced during journeys to downstream by natural purification processes.
(3) Functions of water purification plants for PFCs removal
The PFCs concentration relationship between natural waters and tap waters showed that most of water purification plants can not remove PFCs. Even in plants adopting advance treatment processes such as ozonation and GAC filtration, slight reduction was seen in GAC filter only.
(4) Functions of wastewater treatment plants for PFCs removal
Wastewater treatment plant surveys were conducted at 14 plants in Japan, and at 10 plants in 4 overseas countries. The results thawed (1) most of PFCs can not be removed in wastewater treatment plants, (2) influent concentrations and resultant effluent concentrations are widely ranged, depending on wastewater treatment plants, and (3) activated sludge adsorbs a large amount of FPCs, resulting in high storage of PFCs in wastewater treatment plants.
(5) Treatment method study
The study in water purification plants and wastewater treatment plants showed that ordinal treatment processes hardly remove PFCs. However, some of new processes seem to be effective, such as GAC adsorption, which can remove them during a short period, and UV radiation, which can decompose FPOA with long treatment time. Less
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