Antibiotics are
pharmaceutical compounds widely used to treat a broad range of
infections. These chemicals appear to be recalcitrant compounds when released to water systems, and their presence at the effluent of wastewater treatment plants and surface waters has been widely documented.
Sulfamethoxazole (SMX), a
sulfonamide commonly used to treat urinary
infections, is one of them. Ozonation was proved to be a suitable method to remove SMX
antibiotic in water. However, it is stated that a high
ozone dosage would be necessary to achieve the complete mineralization of the intermediates. In this work, ozonation is coupled with a Sequencing Batch Biofilm Reactor (SBBR) in order to completely degrade SMX and its metabolites from water solutions. Moreover, a precise description of the microbial community in the
bioreactor is provided by means of traditional microscopy and molecular biology techniques. The results obtained showed high Total Organic
Carbon removals at the end of the
biological treatment (89% removal). Furthermore,
nitrates produced during the aerobic SBBR's performance were monitored and eliminated by adding an anoxic stage, achieving an overall
nitrogen removal of 86%. A bacterial community analysis of the SBBR during aerobic and aerobic-anoxic conditions was performed, targeting the bacterial 16S ribosomal
ribonucleic acid (rRNA) gene. These results revealed a dominant contribution of bacteria from the Proteobacteria class, with a major contribution from the Rhizobiales and Burkholderiales orders during the
bioreactor performance, counting 52% of the total population.