Assessment of the aerobic and anaerobic biodegradation of contaminants of emerging concern in sludge using batch reactors

Abstract

This work explores the degradation of xenobiotic compounds in aerobic and anaerobic batch reactors. Different inoculums were spiked with nine emerging contaminants at nominal concentrations ranging between 1 to 2 mg/L (ibuprofen, diclofenac, naproxen, acesulfame, sucralose, aspartame, cyclamate, linear alkylbenzene sulfonates, and secondary alkyl sulfonates). Ethanol was used as co-substrate in the anaerobic reactors. We found that the kinetic decay was faster in the aerobic reactors inoculated with a Spanish (Spn) inoculum compared to a Brazilian (Brz) inoculum, resulting in rection rates for LAS and SAS of 2.67 ± 3.6 h−1 and 5.09 ± 6 h−1 for the Brz reactors, and 1.3 ± 0.1 h−1 and 1.5 ± 0.2 h−1 for the Spn reactors, respectively. There was no evidence of LAS and SAS degradation under anaerobic conditions within 72 days; nonetheless, under aerobic conditions, these surfactants were removed by both the Brz and Spn inoculums (up to 86.2 ± 9.4% and 74.3 ± 0.7%, respectively) within 10 days. The artificial sweeteners were not removed under aerobic conditions, whereas we could observe a steady decrease in the anaerobic reactors containing the Spn inoculum. Ethanol aided in the degradation of surfactants in anaerobic environments. Proteiniphilum, Paraclostridium, Arcobacter, Proteiniclasticum, Acinetobacter, Roseomonas, Aquamicrobium, Moheibacter, Leucobacter, Synergistes, Cyanobacteria, Serratia, and Desulfobulbus were the main microorganisms identified in this study.