Evaluation of Pharmaceutical Products in an Urban Wastewater Treatment Plant in Argentina

KERGARAVAT S.V; SCHMUCK, J; WAGNER, G; GIMENEZ, L; ROMERO, N; RENO, U; POLLA, W; HERNANDEZ, S; GAGNETEN, AM; REGALDO, L

Montevideo

Congreso; SETAC Latin America 15th Biennial Meeting; 2023

Society of Environmental Toxicology and Chemistry

Pharmaceuticals are one of the most important emerging pollutants because they are massively consumed by the population. They are discharged into urban wastewater and end up in receiving water bodies or are treated in treatment plants, which are not designed to remove pharmaceuticals, so in some cases, these compounds are not completely removed and are still present in the effluents even after being treated. In Argentina, the pharmaceutical products more frequently detected in aquatic environments are antibiotics (32%), analgesics (14%), antidepressants (14%), antihypertensives (11%), and anxiolytics (3%). The classical analytical methods of pharmaceutical detection in environmental samples are based on liquid chromatography techniques. Alternatively, electrochemical methods do not require expensive instrumentation and supplies, trained personnel, and can be used in situ. The objective of this work was the development of electrochemical methods to detect pharmaceuticals in urban wastewater in the treatment plant in San Justo city (Santa Fe, Argentina). The analgesic acetaminophen was selected as a model of pharmaceutical in this study. The electrochemical measurements were performed on Dropsens screen printed electrodes (SPE) modified with 50% iron nanoparticles (FeNPs) of 30 nm diameter (90% Fe and10% FeO) provided by Nanomateriales (www.nanotek.ws). The electrochemical technique selected was the square wave voltammetry in the range from 0.2 to 0.8 V, in which the analgesic had an oxidation peak at 0.416 V vs. reference electrode (Ag/AgCl). In order to elaborate the calibration curve of acetaminophen, standard solutions (0.05 to 2.00 mg L-1) in Britton-Robinson buffer 0.1 mol L-1 and NaCl 0.1 mol L-1 at pH = 4.0 were assayed on SPE modified, obtaining a detection limit of 0.5 mg L-1. Since concentrations in the effluents were lower than expected, pre-concentration steps of 100 or 1000 times by solid-phase extraction had to be applied before the analysis. The samples before and after the treatment process in the plant were analyzed and the results were expressed as % removal efficiency [(IC-EC)/IC] x 100, where IC and EC were the acetaminophen concentrations in the influent and the effluent, respectively. Finally, the environmental risk associated with its effluents when are dumped into the Salado River was calculated