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Removal of Triclosan at A Full-Scale Wastewater Treatment Plant in Baltimore

  • Maruf Olaide Yekeen 1,2,*,   
  • Odunayo Joseph Olawuyi  3,   
  • Samendra Sherchan 1,4,5,   
  • Saroj K. Pramanik  1,*

Received: 19 Mar 2026 | Revised: 14 Jun 2026 | Accepted: 24 Jun 2026 | Published: 23 Jul 2026

Abstract

Triclosan is a persistent antimicrobial contaminant frequently detected in municipal wastewater effluents due to its incomplete removal during conventional wastewater treatment processes. This study evaluates the seasonal concentration and removal of triclosan across two full-scale WWTPs relative to their fluctuating physicochemical properties. Grab samples of primary influent (PI), secondary effluent (SE), and tertiary effluent (TE) were collected across four seasons and quantified using solid-phase extraction and spectrophotometric analysis to identify potential drivers of treatment variability. The results demonstrated marked seasonal variation in triclosan concentrations, with the highest influent concentrations detected during summer, while the lowest concentrations were found during spring for Plant A and winter for Plant B. Triclosan removal efficiency also varied seasonally, ranging from approximately 20% in winter to 75% in summer. While primary and secondary processes achieved moderate removal via hydrophobic partitioning, a systemic decline in tertiary removal efficiency was observed during winter. Pooled Pearson correlation analysis revealed significant positive correlation between temperature and removal efficiency, indicating thermal dependency while the inverse relationship between removal efficiency and salinity (r = −0.68, p = 0.063) suggests a potential inhibitory trend on triclosan mitigation. Based on quantifiable triclosan concentrations above the limit of quantification (LOQ; 2.66 µg/L), tertiary effluent concentrations (<2.66–4.72 µg/L) exceeded the adopted PNEC of 0.05 µg/L, suggesting considerable ecological risk, with risk quotient (RQ) values peaking at 94.4. Although plant B exhibited superior triclosan removal efficiency, quantifiable residual triclosan persisted in the tertiary effluents of both facilities. Overall, the findings highlight the importance of seasonal monitoring and optimization of tertiary treatment processes to improve triclosan removal in municipal wastewater treatment plants.  However, the analytical LOQ precluded assessment of ecological risks at lower triclosan concentrations, warranting future monitoring using more sensitive analytical method. The results further demonstrate that urban WWTPs may act as sources of pseudo-persistent triclosan discharge, emphasizing the need for advanced matrix-adaptive treatment technologies and enhanced source-control strategies to mitigate the environmental risks associated with persistent emerging contaminants.

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Yekeen, M. O.; Olawuyi , O. J.; Sherchan, S.; Pramanik , S. K. Removal of Triclosan at A Full-Scale Wastewater Treatment Plant in Baltimore. Environmental Pollution, Risk, and Remediation Insights 2026, 1 (1), 5.
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