OCCURRENCES OF SOLID AND LIQUID PHASE PERFLUORINATED COMPOUNDS (PFCS) IN A MUNICIPAL WASTEWATER TREATMENT PLANT IN JAPAN

摘要

Recently, perfluorinated compounds (PFCs) are recognized as one of the emerging contaminants. The most commonly used PFCs are Perfluorooctane Sulfonate (PFOS) and Perfluorooctanoic Acid (PFOA), which have been used in many kinds of products. Once PFOS and PFOA are released into the environment, these chemicals persist and are distributed throughout the global environment. They have been found in surface water and tap water in both developed and developing countries around the world including North America, Europe and Asia. Especially, now there is growing attention on understanding the occurrence and fate of PFCs I n wastewater treatment plants (WWTPs). PFCs in WWTPs could originate from domestic activities, industrial discharges, or other commercial activities. WWTPs could become the principle point source of PFCs through treated wastewater and sludge. PFCs have been detected in the WWTPs discharges in many countries such as Japan, USA, Canada, Germany, Denmark, Singapore and Thailand. The performances of WWTPs on treatment of PFCs in conventional treatment have been reported. However, there is still lack of information on the performance of advanced processes on treatment of PFCs.The purposes of this study were to identify the occurrences of PFCs from a WWTP in Japan and to evaluate the performance of advanced treatment processes to treat PFCs. Two surveys were conducted in Jan 2006 and March 2010. Samples were collected from influent, effluent, and during the treatment processes including advanced treatment processes (ozonation and biological activated carbon filter). A solid phase extraction (SPE) coupled with HPLC-MMI(ESI)-MS/MS were used for the analysis of these chemicals. PFOS and PFOA were found in both samplings. All ten PFCs were found in most samples in the second sampling. The higher concentration were found in the effluent (PFOS = 30 ng/L, PFOA = 67 ng/L) comparing to the influent. PFOS (9 ng/L) and PFOA (28 ng/L) were found in effluent much less than those in the first sampling. Perfluoronanoic acid (PFNA) (83 ng/L) was highly detected in the effluent of the second sampling. Biological process (A2O) were found ineffectively to remove PFCs. Most PFCs concentrations were increased in the effluent samples. PFCs were also found very high concentrations in sludge. The reasons could be due to bio-accumulation in sludge inside the reactor. The higher concentrations in the effluent could be due to the matrix interference, desorption of PFCs from solids and degradation of precursors. Rapid sand filtration coupled with advanced treatment processes was ineffective to remove PFCs except PFOS. Overall removal efficiencies of PFOA and PFOS in these processes were 26% and 85% in the first sampling, respectively. Overall removal rates of PFOA and PFNA in the second sampling were -14% and 18%, respectively. PFOA concentration increased during biological activated carbon filter in both sampling.