Packed-bed bioreactor-based evaluation of Paracoccus sp. APAP_BH8 potential for acetaminophen biodegradation.

Pharmaceuticals serve as indispensable allies in human and veterinary medication. Acetaminophen (APAP) is extensively consumed as an analgesic and antipyretic medication. The indiscriminate usage of APAP has led to widespread consequences, transforming it into a formidable contaminant of emerging concern, posing severe and underestimated threats. Therefore, to eliminate APAP from the environment, the development of sustainable and efficient methods is compelling. In the present study, Paracoccus sp. APAP_BH8 was utilized for the biodegradation of APAP in a laboratory-scale bioreactor packed with wood charcoal. The response surface methodology was employed for the optimization of distinct degradation parameters, revealing pH of 7.0, inoculum size of 0.3, co-substrate concentration of 15 mg L-1, and APAP concentration of 350 mg L-1 as most favorable. The bioreactor was intended for the removal of APAP at higher concentrations from wastewater. The bioreactor exhibited 90.58% degradation in batch mode studies, and the kinetic parameters Ks, Vmax, and Vmax/Ks were 322.58 mg L-1, 53.52 mg L-1 day-1, and 0.1659 day-1, respectively. For the degradation in continuous mode, the bioreactor was operated at different flow rates and APAP concentrations. The removal efficiency observed in the range of 48.08%-89.35%, and the maximum elimination capacity was 721.19 mg L-1 h-1 at an inlet concentration of 450 mg L-1. Overall, the findings highlighted that Paracoccus sp. APAP_BH8 is a reliable, promising, and sustainable candidate for bioremediation of APAP and similar contaminants from pharmaceutical wastewater within wood charcoal packed-bed bioreactor.