Removal of diclofenac using microbiochar fixed-bed column bioreactor

Abstract

Laccase bound biochar as a fixed-bed column for the removal of emerging contaminant, diclofenac (DCF) provides novel insights into valorization of waste materials, application of environmentally benign sorbents and removal of DCF with possibilities of scaling up for larger applications. Micro-biochar prepared from pine wood (BC-PW) and pig manure (BC-PM) were evaluated for the removal of DCF at environmentally relevant concentrations under continuous fixed–fed column operating conditions. Biochars were characterized for particle size, total metals, elemental composition, surface area, porosity, surface texture, and functional groups. The ligninolytic enzyme laccase was immobilized on micro-biochars and tested for removal/biodegradation of DCF under optimized conditions obtained from adsorption column experiments At an environmentally relevant concentration (500 μg L−1), BC-PM exhibited an adsorption capacity of 4.10 mg g-1 with bed mass: 2 g, flow rate: 2 mL min-1 and at pH: 6.5. For all biochars, uptake of DCF through a fixed-bed column was dependent on the mass of adsorbent (bed height) and DCF concentration. Adsorption capacity decreased with increasing bed height whereas increased with increasing DCF concentration. The Thomas and Yoon–Nelson models were successfully applied to predict the breakthrough curves, indicating that these models were used for designing and scaling – up fixed-bed biochar columns.