Sulfamethoxazole (SMX), one of the most common used antibiotics, is notoriously known for its extreme persistence and the ability to induce microbial antibiotic resistance posing threats to the public health. Trace amount of SMX has been widely detected in a plethora of aquatic environments. However, our knowledge is limited in regard to the effective treatments of this emerging contaminant. In this study, we investigate the removal of SMX using two water treatment approaches: granular activated carbon (GAC) absorption and biodegradation of SMX by an enriched microbial consortium. Batch studies revealed that the adsorption process fitted the best with pseudo-second order kinetics, implying that chemisorption is favorable over physisorption. Further, isothermal studies showed our experimental data were correlated with the Langmuir isotherm model, suggesting that the adsorption of SMX molecules on GAC surface is via localized monolayer interaction. The adsorption rate constant was 0.0048 g/mg/min and the maximum adsorption capacity was 18.31 mg SMX/g GAC. On the other hand, a microbial consortium exhibiting sustainable SMX removal has been successfully enriched from an activated sludge sample collected from a wastewater treatment plant located in Northern New Jersey. This mixed culture degraded 78% of SMX (from 100.0 mg/L to 22.6 mg/L) over 17 days as analyzed by high-performance liquid chromatography (HPLC) with UV detection. The 16S rRNA metagenomic sequencing analysis has been studied to determine the dominant species and a further attempt is made to isolate the SMX-degrading species and investigate the degradation pathways and associated genes/enzymes. This study avails us with two possible treatment alternatives for efficient SMX removal and promotes our fundamental understanding of the kinetics and mechanisms of SMX adsorption and biodegradation.

Evaluation of adsorption and biodegradation for effective sulfamethoxazole removal: Kinetic and mechanism studies

256th National Meeting (2018)

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