Removal of Heavy Metals from Wastewater Using Immobilized Biochar

Biochar, a product of pyrolysis, is receiving increased attention recently due to its unusual physical and chemical characteristics.  In addition to its long-term carbon sequestration capabilities, biochar has been proposed to be used from anywhere from soil augmentation to removal of toxic metals from wastewaters. This paper is about developing a system that optimizes the removal of heavy metals, particularly lead, from wastewater using immobilized biochar in alginate beads.  The advantages of immobilization in a polymeric bead is that biochar can be used as a fine powder, increasing its surface area/mass ratio, and by incorporating the powder into an open polymeric matrix the exposed biochar is more accessible to flow and, for packed bed operations, enables higher flow rates to be used with less pressure drop.  Preliminary experiments in our lab indicate that a bead can be formed that has improved properties per unit mass over the non-immobilized biochar.  The technical significance of developing this new process is important because it could help make remediation of waters contaminated with toxic metals less expensive.