The accelerated biodegradation and mineralization of acetaminophen in the H2O2-stimulated upflow fixed-bed bioreactor (UFBR)

Abstract

The biodegradation and mineralization of acetaminophen (ACT) was evaluated in the upflow fixed-bed bioreactor (UFBR) inoculated with a biomass containing mixture of Pseudomonas spp. and Bacillus spp. as the dominant bacteria under H2O2 stimulation. The effect of various main operational variables was evaluated on the performance of the UFBR for ACT removal. The maximum ACT removal was obtained at the H2O2:ACT molar ratio of 14. H2O2 induced the bacteria in biofilm for the in-situ generation of peroxidase resulted in the acceleration of ACT decomposition into more biodegradable intermediates. Over 99% of ACT and 72% of its TOC at initial ACT concentrations up to 300 mg/L could be eliminated under optimum H2O2:ACT molar ratio in the batch UFBR within 12 h recirculation time. The specific biodegradation rate of ACT increased from 1.0 to 4.1 mg ACT/gbiomass.h when the inlet loading rate was increased from 8.3 to 41.7 g ACT/m3.h. In addition, the complete biodegradation and TOC removal of ACT was observed in the continuous UFBR at the hydraulic retention time of 6 h and the presence of 1–20 g/L salinity without inhibition. The presence of H2O2 could efficiently stimulate the production of bacterial peroxidase, which in turn resulted in the acceleration of ACT biodegradation and mineralization. Therefore, the H2O2-stimulated UFBR is an efficient and viable technique for in-situ production of peroxidase used for acceleration of ACT biodegradation.