Treatment of 17α‑ethinylestradiol, 4‑nonylphenol, and carbamazepine in wastewater using an aerobic granular sludge sequencing batch reactor

This study quantifies the removal of a mixture of commonly detected emerging contaminants, 17α‑ethinylestradiol (EE2), 4‑nonylphenol (NP), and carbamazepine (CBZ) from synthetic wastewater using aerobic granular sludge in a sequential batch reactor. The emerging contaminant concentration in the influent wastewater was maintained near 500 μg/L for the duration of the experiment. Removal of EE2, NP, and CBZ is comprised of both adsorption and degradation. In general, the main removal mechanism for the emerging contaminants was initially adsorption, however it transitions to degradation as the adsorption capacity is saturated. The stabilized degradation for EE2 and NP in the SBR, was 16.09 μg/g and 20.05 μg/g, respectively. There was limited degradation of CBZ during the anaerobic phase. Both the Langmuir and Freundlich adsorption isotherms fit the data well and constants for the equations are calculated. The constants for the Langmuir Isotherm are found to be (X/m)_max = 36.23, b = 0.0019 for EE2 and (X/m)_max = 44.25, b = 0.0004 for CBZ. None of the tested compounds were found to be detrimental to the performance of the aerobic granules, and high macronutrient removal efficiency was maintained. The granule sludge bed and particle size were not negatively affected by EE2 and NP, however, carbamazepine appeared to interfere with the mechanism of granule formation resulting in a decrease in particle size during the experiment.