Evaluation of a coagulation/flocculation-lamellar clarifier and filtration-UV-chlorination reactor for removing emerging contaminants at full-scale wastewater treatment plants in Spain.

The presence and elimination of 25 emerging contaminants in two full-scale Spanish wastewater treatment plants was studied. The tertiary treatment systems consisted of coagulation, flocculation lamellar settlement and filtration (pulsed-bed sand filters) units, and disinfection was carried out by medium pressure UV light lamps and chlorination. Diclofenac and carbamazepine were found to be the emerging contaminants with the highest concentrations in secondary effluents. Photodegradable emerging contaminants (e.g. ketoprofen, triclosan and diclofenac) were removed by filtration-UV light radiation-chlorination whereas most hydrophobic compounds (e.g. galaxolide and tonalide) were eliminated by coagulation-flocculation followed by lamellar clarification, a unit in which a seasonal trend was observed. Overall mass removal efficiency was about 60%. 1-(8-Chlorocarbazolyl) acetic acid, an intermediate product of the photodegradation of diclofenac, was detected after filtration-UV-chlorination, but not after coagulation-flocculation and lamellar clarification. This study demonstrated potential for general applicability of two established tertiary treatment systems to eliminate emerging contaminants.