Investigating through unsaturated column tests

The growing consumption of pharmaceuticals together with their incomplete removal in wastewater treatment plants implies the occurrence of these compounds in natural water resources.

To investigate the natural attenuation of selected pharmaceuticals during vadose zone infiltration, unsaturated column experiments, filled with a sandy-loamy soil, were performed using two input concentrations (100 and 1000 μg L−1) of a mixture of pharmaceuticals. The five analyzed compounds were caffeine, acetaminophen, sulfamethoxazole, naproxen and carbamazepine.

Caffeine and acetaminophen were never detected at the column outlet indicating a low environmental concern. On the other hand, carbamazepine is among the selected contaminants the most persistent. Attenuation of the detected pharmaceuticals could be reproduced by a combination of retardation and removal approaches.

A dependence of removal rates on input concentrations was detected for sulfamethoxazole and naproxen attributed mainly to decreased metabolism of microorganisms when a higher input concentration is applied. Two transformation products (N4-Acetylsulfamethoxazole and epoxycarbamazepine) derived from sulfamethoxazole and carbamazepine transformation, respectively, were detected during the experiment with the highest input concentration.

The research carried out by Dr. Irene de Bustamante,  Dr. Virtudes Martínez and Dr. Raffaella Meffe from IMDEA Water Institute in collaboration with Dr. Claus Kohfahl from Instituto Geológico y Minero de España. The results of research have been published in June 2017 in Chemosphere.