Abstract

This study evaluates the hygienic safety of the HansanㆍGeojeman area based on hygiene indicator bacteria from seawater and shellfish samples collected between 2015 and 2023, by constructing the wastewater treatment plant and expansion of its service area. The geometric mean and 90th percentile values of fecal coliforms in seawater showed a significant reduction, from 2.5-6.5 MPN/100 mL to 2.1-3.7 MPN/100 mL (a decrease of 12.0-43.1%) and from 10.7-62.3 MPN/100 mL to 3.6-13.7 MPN/100 mL (a decrease of 44.9-78.0%), respectively. Additionally, the geometric mean of Escherichia coli in shellfish decreased from 25.0-26.5 MPN/100 mL to 19.0-20.6 MPN/100 mL, showing a decrease of 17.6-28.3%. Following the expansion of the wastewater treatment plant's service area, fecal coliform levels in Naegan stream decreased from 3.8 log MPN/100 mL to 2.1 log MPN/100 mL, and the affected range was reduced from 670 meters to 160 meters. These results showed that the importance of managing both land-based and marine pollution sources, including the expansion of wastewater treatment plant, to ensure the hygienic safety of shellfish