Removal of pharmaceuticals and personal care products from domestic wastewater using rotating biological contactors

Abstract

New emerging contaminants are being released into the environment. Some of these are not removed in conventional wastewater treatment plants. Therefore, the aim of this study was to evaluate a pilot-scale rotating biological contactor (RBC) as a technology applicable to the removal of emerging pollutants. The work focused on two pharmaceutical compounds in particular (carbamazepine and sildenafil citrate) and a personal care product (methylparaben). The behavior of the system was evaluated for the individual addition and mixture of the three compounds, using organic loads similar to those of secondary and tertiary treatment effluent. The working flow rate was 70 mL/min, and the concentration of the compounds was 200 μg/L. The organic load was evaluated at different times. Dissolved oxygen, temperature, conductivity and pH were measured in situ on each sampling. Removal efficiencies greater than 98% were achieved for methylparaben, but less than 20% for pharmaceuticals. The average removal efficiency was 95% for the organic matter in the different tests. In this investigation, it was observed that the RBC allowed the effective removal of emerging contaminants which have flat molecular geometry and essential chemical elements, such as methylparaben. However, its effectiveness was poor in removing contaminants formed from more complex structures such as carbamazepine and sildenafil citrate. The operational stability of the system was not affected when these compounds were incorporated in amounts similar to those found in wastewater.