1C-O1-1445 PDF
Evaluation of sewage exfiltration in groundwater by artificial sweeteners and persistent pharmaceuticals as chemical tracers
In recently years, large amounts of low-calorie artificial sweeteners have been used in a wide variety of beverages and foods in the world. Our preliminary study showed that extremely high concentrations of acesulfame were randomly detected in groundwater samples collected from downtown area in Kumamoto city. This may imply the leakage of wastewater into groundwater, due to breakdown of aging sewer pipes. In this study, we analyzed artificial sweeteners in aqueous matrices to confirm the results of our preliminary study and to estimate exfiltration rate in Kumamoto. Acesulfame was detected in influents of wastewater treatment plant and groundwater samples at mean concentrations of 907 ng/L and 3.29 ng/L, respectively. The acesulfame concentrations of several groundwater samples collected from downtown area were more than 20-folds greater than the background levels, although the distance of these sampling points were very close. This suggests the possibility of sewage exfiltration in groundwater in Kumamoto downtown area. The sewer exfiltration rate were estimated that approximately 2.1 percent of the sewage in annual amount of wastewater is leaked into groundwater. The exfiltration rate was comparable with the values of other cities, such as Tokyo, Japan and Nottingham, UK, which were calculated by persistent pharmaceuticals in groundwater.