Discharge Characteristics of Alkylphenols in Industrial Wastewater and Ecological Risk Assessment in Busan, Korea

This study presents the first comprehensive assessment of discharge characteristics and ecological risks associated with alkylphenols, specifically nonylphenol (NP) and octylphenol (OP), in industrial wastewater across Busan, Korea. A total of 146 samples were analyzed revealing detection frequencies of 18% for NP and 54% of OP. Higher concentrations of both compounds were predominantly observed in wastewater in effluents from steel and metal processing (NP: ND[not detected] to 21.838 μg/L, OP: ND to 206.053 μg/L) and repair and car wash facilities (NP: ND to 54.039 μg/L, OP: ND to 60.564 μg/L). The OP concentrations were significantly higher than those of NP, suggesting its growing use as a replacement for NP following the stricter regulatory controls on NP. Hazard quotient (HQ) calculations revealed that NP exceeded the high-risk threshold (HQ≥1) in 4.1% of the samples, whereas OP surpassed this threshold in 28.1% of samples, underscoring its greater potential for environmental harm. Despite average removal efficiencies of 94% NP and 80% for OP in public sewage treatment plants, the persistence and ecological relevance of these compounds remain concerning. The findings emphasize the need for targeted monitoring and mitigation strategies to address alkylphenols contamination in industrial effluent.