Metronidazole Removal from Wastewater via Biomass Coimmobilized with Powdered Activated Carbon: Effects of PAC, Bead Volume, and Organic Carbon Content

Abstract

The removal of metronidazole (MNZ), a pharmaceutical antibiotic, from a synthetic wastewater matrix will be investigated in this study using biomass immobilized with powdered activated carbon (PAC) in an alginate matrix (Al–AC–Bio). First, the Al–AC–Bio beads will be synthesized using 2% sodium alginate (SA 2%), 0.1% PAC, and 12.5 g/L mixed biomass. For comparison, beads without PAC will be prepared with SA and biomass (Al–Bio) under similar conditions. The MNZ removal experiments will be conducted under the following conditions: MNZ of approximately 1 mg/L; bead loading of approximately 5%, 10%, and 20%; and wastewater organic carbon (OC) of approximately 300 mg/L (low carbon) and 1000 mg/L (high carbon). The MNZ removal was mainly abiotic and followed second-order kinetics under all conditions. A maximum MNZ removal efficiency of 87.7% and specific MNZ removal (SMR) capacity of 0.34 mg/g were observed using Al–AC–Bio after 24 h. The increase in bead concentration and organic content showed an insignificant improvement in MNZ removal efficiency. However, total organic carbon (TOC) and ammonia (NH3) removal were 67.4% and 90.2%, respectively, under optimized conditions. The addition of PAC showed a significant improvement in MNZ removal and insignificant improvements were observed for TOC and NH3 removal. The PAC–biomass beads with lower bead loading could be efficient for the removal of MNZ and NH3 from wastewater.