Chemicals of emerging concern in wastewater treatment plants from Mendoza: Environmental study in a semiarid region of Argentina

Abstract

WBE aims to quantify community exposure, discover exposure-outcome associations, and trigger policy and technological or societal intervention strategies to promote exposure prevention and public health. This paper aimed to apply a WBE framework to identify a wide range of chemicals of emerging concern (CEC) in two wastewater secondary treatment plants from Mendoza, Argentina, which treated sewage is used for crop irrigation in a semiarid region. Thus, WBE plays a fundamental role in water reuse in a semiarid region stressed by water demand and scarcity. This is the first report of an extensive group of CEC in the liquid and solid particulate matter (SPM) phase of inlet and outlet samples of WWTP of Argentina. It aimed to estimate capita usage and the removal efficiency of the studied WWTPs. This is also a unique testing site for the treatment process – an open sky serial lagoons biologically activated vs heavily engineered activated sludge treatment process. Of the 138 CECs targeted in this study, 74 were detected in liquid-phase wastewater influent. Among the most prevalent CEC groups were analgesics/metabolites and antidepressants/metabolites. Out of the 96 compounds analysed in suspended particulate matter (SPM), 36 were detected. SPM accounted for approximately 2% at WWTP-A and 6% at WWTP-B of the total analysed CEC load with SPM enriched with antibiotics and UV filters. Population-normalised loads showed little inter-day variation for most of the CECs between the two WWTPs, indicating community-driven usage of CECs. The lagoon-based wastewater treatment process utilised in the study sites showed variable removal efficiency with >80% paraben removal but suboptimal (<50%) removal of benzophenones and bisphenol A. Antibiotics showed variable removal rates with trimethoprim, triclosan, metronidazole, and ofloxacin exceeding 60%. In comparison, little or no removal (<60%) was observed for clarithromycin, sulfamethoxazole, and tetracycline. Most cardiovascular drugs, antihistamines, and antiepileptics were poorly removed (<50%), while antidepressants and NSAiDs/analgesics showed much higher removal rates (>60%). Variable but high, removal rates were observed for illicit drugs, e.g. with cocaine removal >70% vs benzoylecgonine’s removal <30% as benzoylecgonine is cocaine’s transformation by-product. Comparison of per capita usage of CECs in Argentina and the UK showed that cities tested in the two countries had comparable per capita usage of many pharmaceuticals with differences observed for antidepressants (much higher usage of venlafaxine in Argentina), cardiovascular drugs (much higher usage of valsartan in Argentina), exposure to bisphenol A (higher in the UK) and illicit drugs usage (with higher cocaine use in Argentina vs MDMA in the UK).