Pharmaceutical residues within sewage sludges
The potential threat of pharmaceuticals and personal care products (PPCPs) to the environment has emerged as a topic of concern in recent years. To date there exists a dearth of analytical methods to empirically determine their occurrence in solid media. This 3-year research and development project focused on a number of topics surrounding the exposure of pharmaceuticals to the terrestrial environment through land-spreading of municipal biosolids (sludges) on agricultural land. More specifically the aims of the project were: i) To identify which PPCPs may occur at significant levels in wastewater treatment sludges; ii) To develop robust analytical methods for soil and sludge analysis; iii) To compare any occurrence data with that from a European case-study; iv) To determine the solid-water partition coefficient for all compounds in aqueous sewage sludge and soil suspensions; v) To model sorption data in order to identify preferred sorption modes in the environment; vi) To assess the mobility of such compounds in sewage sludge amended soils after exposure to rainfall. Pharmaceuticals chosen for studyA total of 61 PPCPs were chosen to encompass a wide variety of therapeutic classes specifically deriving from antibiotics analgesics non-steroidal anti inflammatory drugs (NSAIDS) beta-blockers anti-psychotics and illicit drugs of abuse. Many of these compounds were chosen based on sales data for the Republic of Ireland (Irish Medicines Board) and Norway. Antibiotics were of particular concern and a selection of 14 compounds covering sulfonamides macrolides fluoroquinolones antibacterials bacteriostatics and antifungals were included. Analytical methodologies: An analytical method was developed to determine a large selection of frequently prescribed and consumed pharmaceuticals in biosolid enriched soils and digested sludges. Using a combination of pressurised liquid extraction (PLE) solid phase extraction (SPE) and liquid chromatography with tandem mass spectrometry (LC-MS/MS) it was possible to detect analytes in each sample type at the low-sub ng/g level. Solid phase extraction efficiencies were compared for 6 different sorbent types and it was found that Waters Oasis HLB cartridges offered enhanced selectivities with 20 analytes showing final method recoveries 60 % in both soils and digested sludges. The method was validated for linearity range precision and limits of detection in both sample matrices. All analytes were then determined in sludge enriched soils as well as the precursor thermally dried sludge fertilizer produced from a primary wastewater treatment plant. Levels of the antibacterial agent triclosan were found to exceed 20 g/g in digested sludge and 5 g/g in thermally dried sludge cake. Significant traces of carbamazepine and warfarin were also detected in the above samples. Alternative separation methods were also investigated and involved the characterisation of ultra-high pressure liquid chromatography and long monolithic column technologies to reduce ion suppression effects in mass spectrometry.
If you want to read more about this project, you can do so at erc.epa.ie.
Environmental Protection Agency 2005-FS-30-M1
Keywords: Wastewater; Treatment; Sludges; Pharmaceuticals