Antibiotics in ethanol fuel production: analysis, dispersion in the environment and effects on vinasse digestion

Author(s)

Josiel José da Silva

• Document type: Doctoral Thesis
• Press: Araraquara. 2021-06-11.
• Institution: Universidade Estadual Paulista (Unesp). Instituto de Química. Araraquara
• Defense date: 2021-05-14
• Advisor: Nelson Ramos Stradiotto

Abstract

Vinasse is a liquid residue from sugarcane ethanol fuel production. This residue has been used for more than 4 decades in the fertigation of the soil of the sugarcane fields, providing water and nutrients. Despite the agronomic and economic importance of this practice, fertigation can be a source of contaminants for the environment, especially in relation to antibiotics, which are used in the ethanol production process. Thus, the objective of this work is to evaluate possible risks associated with the practice of fertigation, from the point of view of the dispersion of organic contaminants in the environment, with a greater focus on antibiotics, and to evaluate the impact of the presence of antibiotics on anaerobic digestion of vinasse. For this, three different approaches were adopted, being: i) development of LC-MS/MS method for the analysis of antibiotics (monensin, penicillin G, virginiamycin M1, virginiamycin S1, tetracycline and erythromycin) in vinasse, being evaluated the techniques SPE, SALLE and on-line SPE for sample preparation. ii) Analysis of vinasse, soil and groundwater samples from fertigates areas with vinasse, using two methods. The first, based on LC-MS/MS for the determination of 32 antibiotics from multiple classes, being that QuEChERS and PLE extraction techniques were evaluated for soil samples preparation. The second, based on suspect screening analysis employing advanced strategies based on LC-HRMS to assess the presence of 7811 contaminants, including pesticides, pharmaceuticals and a wide range of industrial chemicals, among other substances. iii) Evaluation of the inhibition of methane production in anaerobic digestion of vinasse contaminated with different concentrations of the antibiotics monensin, penicillin G and tetracycline in a batch reactor (500 mL). As result, it was possible to verify that the SPE, SALLE and on-line SPE techniques were suitable for the extraction of most analytes in vinasse. In addition, with the developed on-line SPE-LC-MS/MS method, it was possible to verify that monensin can resist to the ethanol production process and was detected in a vinasse sample at a concentration of 14.3 ng mL-1. In the LC-MS/MS analyzes for multiple classes antibiotics, no additional contaminants were detected, and the QuEChERS and PLE extraction techniques achieved similar performance, with specific positive points for each case. The analysis by LC-HRMS allowed the identification by tentative of 19 contaminants of environmental concern in the vinasse, 12 in the soil and 25 in the groundwater from fertigated areas. However, none of these compounds are causally linked to vinasse, and the results showed the existence of other potential sources of contamination for the analyzed samples, mainly associated with modern agricultural activity. The digestion experiments showed that the studied antibiotics can partially inhibit the production of methane at concentrations of 0.5 ppm for monensin, 1.0 ppm for tetracycline and 0.01 ppm for penicillin G. These results indicate that vinasse contaminated with antibiotics can compromise the efficiency of biogas production by anaerobic digestion. (AU)

• FAPESP's process: 16/06352-4 - Antibiotics in fuel ethanol production: analysis, dispersion in the environment and effects on vinasse biodigestion
• Grantee: Josiel José da Silva
• Support Opportunities: Scholarships in Brazil - Doctorate