Estudo comparativo dos processos de eletrocoagulação e fotólise com aeração na remoção de fármacos em efluentes de estação de tratamento de esgoto (ETE)

Abstract

The extensive use of pharmaceuticals results in their release into wastewater treatment plants. Even at reduced concentrations, these compounds can significantly impact the environment and human health. This study investigated optimal conditions of electrocoagulation (EC) and photolysis with aeration (AF) to remove the drugs trimethoprim (TMP), paracetamol (PAR) and ibuprofen (IBP) and total organic carbon (TOC) from domestic sewage. Studies of the variables pH, current density and duty cycle for CE, as well as pH and flow for AF were carried out, using the response surface methodology based on the central composite design. In addition, an analytical method was developed using simplified QuEChERS (s-QuEChERS) and HPLC-DAD to quantify TMP, PAR and IBP in effluents from Sewage Treatment Plants (WWTP). All drugs showed good linearity (correlation coefficients > 0.99), with LDs and LQs ranging from 0.54 to 1.76 mg L-1 and 1.64 to 5.34 mg L-1. The results confirmed the precision and accuracy of the method. Response surface plots demonstrated greater removal when pH, current density, and duty cycle were elevated in the EC process. However, in the AF process, despite the increase in removal with pH, the flow showed an antagonistic effect. Ideal conditions (pH 5.45, current density 12.14 A m-2 and duty cycle 55.10%) achieved removal rates of 43.23% (TMP), 45.52% (PAR), 79.07% (IBP) and 57.16% (TOC) for the EC process and for the FA process the optimized conditions (pH 7.02 and flow of 99.14 mL min-1) achieved removal rates of 36.00 % (TMP), 41.85% (PAR), 46.01% (IBP) and 28.92% (COT). Analysis of variance (ANOVA) validated second-order polynomial models, with high F values and low probability (p < 0.0001), indicating a strong correlation between experimental and predicted levels for drug removal and organic matter. Electrocoagulation showed greater efficacy in drug removal and TOC compared to photolysis with aeration. Thus, electrocoagulation was chosen as the main treatment method, while photolysis with aeration was used as a complementary step. There was a significant increase in the removal of drugs and TOC with the combination of the processes, reaching: MPR from 43.03% to 75.95%, PAR from 45.75% to 71.78%, IBP from 78.79% to 96.01% and TOC from 56.77% to 78.72%.