Effective removal of zinc from industrial plating wastewater using hydrolyzed olive cake: Scale-up and preparation of zinc-Based biochar

In this study, the removal of zinc from plating wastewaters using fixed bed columns packed with hydrolyzed olive cake was investigated. This work discusses the significance of the scale-up and provides a brief overview of the potential uses of exhausted biosorbent for the generation-of-zinc-based materials. First, biosorption studies were performed to analyze biosorption behavior of hydrolyzed olive cake in different sized columns. Influence of important design parameters such as contact time, linear velocity and bed height/diameter ratio on biosorption performance was studied. Results indicated a significant effect of contact time on scale-up. Higher bed depths increased the biosorption capacity due to a larger dose of absorbent in the packed columns. As the flow rate increased, the breakthrough time decreased and the exhaustion of the column was reached faster. In addition, operating at the same contact time and bed height/diameter ratio and at a linear velocity much higher in the pilot column, the zinc uptake capacity was found to be higher. Better biosorption results could be due to velocity influencing the mass transfer and hydraulics improving the fluid dispersion. Finally, exhausted biosorbent was subjected to different thermal treatments. Preliminary tests showed that zinc-loaded solid can be recycled for the generation of zinc-based materials. (C) 2019 Elsevier Ltd. All rights reserved.