Kinetics of sorption of selective serotonin reuptake inhibitors fluoxetine and citalopram and applications to a mixed-media wastewater treatment filter

Mayes, Meredith
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Nyman, Marianne
Kilduff, James
Zimmie, T. F.
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Environmental engineering
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Fluoxetine and citalopram are among the top five most prescribed antidepressants in the United States. These compounds and other pharmaceuticals are currently discharged in wastewater effluent with no national standards on removal. The evaluation to remove fluoxetine and citalopram from water supplies began with isotherms. The isotherms for this data show that activated carbon (AC) can be a considered a suitable component for the removal of fluoxetine and citalopram. The kinetics of fluoxetine and citalopram sorption proves that the two compounds maximally sorb to sand, sediment and AC within a 30-minute time frame. This would allow for the usage of either a rapid or slow sand filter mixed with AC to maximize removal of fluoxetine and citalopram from the aqueous phase. This can be concluded from the filtration runs with these compounds. Loads of 40 mg/L of fluoxetine were almost completely removed up to 18 hours after which a preferential flow path within the column developed. This flow path negatively affected sorption. However, even after 5 days, fluoxetine was still removed from the system with 29% efficiency. Citalopram filtration began with 30 mg/L of citalopram and had 95% removal efficiency. Together, fluoxetine and citalopram were effectively removed when run through the filter media together. This indicates that fluoxetine and citalopram at the concentration of 12 mg/L each do not compete to bind AC or sand. Furthermore, the filter effectively reduced turbidity of the influents. The filter removed 99% of the fluoxetine influent turbidity. The filter also removed 95% citalopram influent turbidity. When fluoxetine and citalopram were run together, 99% of the turbidity of the mixed compound influent was removed from the system.
May 2013
School of Engineering
Dept. of Civil and Environmental Engineering
Rensselaer Polytechnic Institute, Troy, NY
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