Spatial and temporal occurrence of pharmaceuticals and illicit drugs in the aqueous environment and during wastewater treatment: new developments

Abstract

This paper presents, for the first time, spatial and temporal occurrence of a comprehensive set of >60 pharmaceuticals, illicit drugs and their metabolites in wastewater (7 wastewater treatment plants utilising different treatment technologies) and a major river in the UK over a 12 month period. This paper also undertakes a comparison of the efficiency of processes utilised during wastewater treatment and it discusses under-researched aspects of pharmaceuticals and illicit drugs in the environment including sorption to solids and stereoselectivity in the fate of chiral drugs during wastewater treatment and in receiving waters. The removal efficiency of analytes strongly depended on the type of wastewater treatment technology employed and denoted <50% or >60% in the case of tricking filter and activated sludge respectively. It should be stressed, however, that the removal rate was highly variable for different groups of compounds. A clear increase in the cumulative concentration of all monitored compounds was observed in receiving waters; thus highlighting the impact of WWTP discharge on water quality and the importance of the removal efficiency of WWTPs. No seasonal variation was observed with regard to the total load of targeted compounds in the river each month. The concentration of each analyte was largely dependent on rainfall and the dilution factor of WWTP discharge. These results indicate that although the drugs of abuse are not present at very high concentrations in river water (typically low ng L(-1) levels), their occurrence and possible synergic action is of concern, and the study of multiple groups of drugs of abuse is of significant importance.