Occurrence of Pharmaceuticals in WWTP Influents

Abstract

Pharmaceuticals are a class of emerging micropollutants whose detection in surface waters have been attributed to domestic effluent discharges. Although concerns over potential ecological and health impacts have been raised for certain pharmaceutical groups (e.g., antibiotics), to date there are no discharge standards for these chemicals. Given that most ecotoxicity studies for pharmaceuticals were performed in laboratory settings that may differ from environmental conditions, there is a need to establish their actual environmental concentrations. In the current study, we performed a systematic review of literature to examine the influent sewage concentrations of erythromycin (prescription antibiotic) and ibuprofen (over-the counter pain reliever) in municipal wastewater treatment plants (WWTPs). The literature search and screening procedure yielded datasets from a total of 250 WWTPs which were grouped according to plant capacity (small, < 10 mega gallons per day, MGD; medium, 10–100 MGD; and large, > 100 MGD) and geographic location (Asia, Europe, North America). Measured erythromycin levels in the influent ranged from $10^{-1}\ {\mu} \mathrm{g}/\mathrm{L}$ to $1\ {\mu} \mathrm{g}/\mathrm{L}$, while ibuprofen levels ranged from $10^{-1}\ {\mu} \mathrm{g}/\mathrm{L}$ to $10^{2}\ {\mu} \mathrm{g}/\mathrm{L}$. Average erythromycin levels were about the same across all WWTP sizes and regions. Average ibuprofen levels were significantly higher in small WWTPs than in large WWTPs ($\mathrm{p} < 0.01$). Average ibuprofen levels were highest in North America −102 times higher than in Europe and 10 times higher than in Asia. With respect to WWTP operation, research findings suggest that small WWTPs should receive the same consideration as larger WWTPs where the level of treatment (i.e., degree of removal) for pharmaceuticals is concerned. Furthermore, the summarized occurrence data presented in this study provide insights to WWTP managers in assessing if enhanced WWTP treatment or downstream risks assessment for receiving streams are needed.