Accumulation, transformation, and environmental implications of acetaminophen and ibuprofen in sewer systems

Abstract

The widespread use of acetaminophen (APAP) and ibuprofen (IBU) since the SARS-CoV-2 pandemic has strongly impacted the environment due to their incomplete metabolism and excessive discharge into sewer systems. This study evaluated the accumulation and transformation of APAP and IBU in a laboratory sewer system under long-term operation. APAP and IBU attenuation followed pseudo-first-order kinetics (R² > 0.95), with the maximum attenuation rates of 62.64% ± 0.02% and 47.38% ± 1.49%, respectively. Accumulation of APAP and IBU was observed in sediments, with enrichment increasing over time, reaching the maxima of 107.66 ± 4.71 ng/g and 35.60 ± 0.85 μg/g, respectively. The stabilization of APAP and IBU in sediments was primarily attributed to hydrogen bonding and hydrophobic interactions, as indicated by FTIR-2D-COS analysis and molecular docking simulations. Metagenomic analysis revealed enrichment of hydrolase and oxidase genes (amiA/B/C and CYP199A2) related to cell wall reconstruction and xenobiotic metabolism under APAP stress, as well as ACAT (a transferase related to energy metabolism) under IBU stress, suggesting potential transformation pathways of APAP and IBU in sewers. These findings indicate that the synergistic interaction between sediment adsorption and microbial degradation governs the spatiotemporal dynamics of pharmaceutical behavior in sewer systems. Notably, drug enrichment in sediments may increase long-term contamination risks due to delayed pollutant release and enhanced adhesion potential., This study provides crucial evidence for sewer system management and the effective control of emerging pharmaceutical contaminants.

Graphical abstract

Keywords

Acetaminophen / ibuprofen / Sewer systems / Accumulation and transformation / Metagenomics / Molecular docking simulation

Highlight

	● The attenuation of APAP and IBU followed pseudo-first-order kinetics.
	● 2D-COS reveals the reaction order of functional groups in APAP and IBU adsorption.
	● Molecular docking verifies strong hydrogen bonding and hydrophobic interactions.
	● Metagenomic and LC-MS/MS analyses reveal APAP and IBU transformation pathways.

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