Distribution, Sources, and Risk Assessment of Emerging Contaminants in the Effluents from Large-Scale Wastewater Treatment Plants in Guangzhou Central Districts, South China

The large-scale wastewater treatment plants (WWTPs) in developed regions collect volumes of wastewater containing various emerging contaminants (ECs) every day, but without any effective process to eliminate them. Therefore, it is of vital importance to study the occurrence of ECs in the effluents from WWTPs. In this study, the concentration levels and pollution characteristics of typical ECs in effluents were investigated for source identification and risk assessment. In total, 13 of 39 analyzed ECs were detected in the effluents, with the highest detection concentration at 706 µg/L (oxolinic acid). Sulfaphenazole showed the highest detection frequency at 100%, while Liede WWTP (1.2 million m³/day), located at Tianhe District, was with the highest detection concentration (899 µg/L) among all sampling sites. Parallel factor analysis was applied to identify the dissolved organic matters (DOMs) of excitation–emission matrix spectroscopy (EEMS) first. Based on previous research data, the connection between DOMs and pollution sources could be built. Then, principal component analysis (PCA) and Pearson’s correlation analysis were used to determine the correlation between ECs and DOMs. Finally, ecological and health risk quotients were calculated for the risk assessment of ECs. The results illustrated that oxolinic acid, sulfaphenazole, sulfaquinoxaline, sulfadimethoxypyrimidine, penicillin V, and flumequine were potentially discharged from human activities and livestock, poultry, and aquaculture industry; the possible sources of sulfadoxine and nafcillin were agricultural activities, food production, and catering industry; sulfapyridine and erythromycin were believed to come from hospital wastewater; and the discharges of lincomycin, sulfameter, and sulfamerazine were related to petrochemical industry or chemical production activities. Except for sulfadoxine, all detected ECs posed a high or median risk on aquatic ecosystem, which is enough to threaten aquatic organisms. Even though only oxolinic acid, sulfaquinoxaline, and sulfadimethoxypyrimidine presented a potential risk on humans’ health, the cumulative effect of ECs in the human body still needs attention. The threats of ECs from large-scale WWTPs in China’s developed regions are pointed out for the first time, which could possibly bring widespread attention on emerging pollution from WWTP effluents, potentially advance the introduction of relevant policies, and provide the direction and target pollutants for follow-up mitigation actions.