Fate evaluation of pharmaceuticals in solid and liquid phases at biological process of full-scale municipal wastewater treatment plants

Abstract

In the last few decades, pharmaceuticals have saved millions of lives. However, their overconsumption is causing several negative impacts on human and wildlife endocrine systems. To date, numerous studies have investigated the occurrence and fate of pharmaceutical in municipal wastewater treatment plants (WWTPs). However, efforts to understand the removal mechanism of pharmaceuticals in WWTPs by simultaneously investigating pharmaceuticals in liquid and solid phases are limited. In this study, a simultaneous assessment of pharmaceuticals in liquid and solid phases was performed using samples collected from biological processes of three municipal WWTPs that adopted different treatment configurations. Among the three WWTPs, noticeable mitigation of macrolide antibiotics was observed in WWTP_A, which adopted membrane bioreactor. 12 pharmaceuticals, which showed positive removal in all sampling campaigns, were selected to evaluate the removal mechanism. The removal of acetylsalicylic acid, ciprofloxacin, ibuprofen, and ofloxacin by sorption in each WWTP seems to be acceptable as per the calculated sorption coefficient (Kd) value and qualitative detection. However, it is inadequate to only evaluate using the Kd values of acetaminophen, caffeine, and cefradine of WWTP_B owing to their lower qualitative detection in the solid phase. Interestingly, the calculated biodegradation constant value of ciprofloxacin (0.41–5.07 L/gMLSS·d) (mitigation pathway of electrostatic interaction) in the anaerobic reactor of WWTP_A was similar to that of caffeine (0.84–5.20 L/gMLSS·d) indicating a high biodegradability in wastewater treatment. Therefore, the simultaneous analysis of both liquid and solid phases provides valuable information for the detailed evaluation of the fate of pharmaceuticals in biological processes of municipal WWTPs.