Pharmaceutical Residues in Wastewater Treatment Plants and Surface Waters in Bangkok

Abstract

Pharmaceutical residues are increasingly found in wastewater treatment plant effluents and river water in very low concentrations at nanograms per liter levels in many countries. In this study, samples were collected from seven wastewater treatment plants (WWTPs) and downstream surface waters in Bangkok, Thailand during July and October 2009 and January 2010. Solid phase extraction (SPE) followed by high-pressure liquid chromatography-mass spectrometry-mass spectrometry (HPLC/MS/MS) technique were used to detect eight pharmaceuticals including caffeine, acetaminophen, roxithromycin, ciprofloxacin, trimethoprim, lincomycin, enrofloxacin, and erythromycin. Levels of pharmaceutical residues in the influents on average were the highest for caffeine (9,052 ng/L), followed by acetaminophen (8,630 ng/L), and roxithromycin (235 ng/L). The same three pharmaceuticals showed the top three levels in the effluents (caffeine: 797 ng/L, acetaminophen: 92 ng/L, and roxithromycin: 50 ng/L). The concentration of caffeine was also the highest in downstream surface water samples (2,393.4 ng/L). Acetaminophen (839.3 ng/L) and roxithromycin (54.7 ng/L) were at the second and third highest levels. Caffeine and acetaminophen in WWTP effluents were at very low levels compared with the influent concentrations.