Enhanced arsenic removal using biochar immobilized bacteria encapsulated in polyvinyl alcohol-sodium alginate beads: Fabrication, optimization and performance evaluation

Arsenic ranks first on the Substance Priority List of the Agency for Toxic Substances and Disease Registry and causes a wide range of health problems, including cancer and even death. The present work was focused on the removal of arsenic using bacteria, Proteus alimentorum strain TY6 and Pseudomonas aeruginosa strain K7Pb, immobilized on peanut shell biochar [0.05 % (w/v)] and encapsulated in polyvinyl alcohol (PVA) - sodium alginate (SA) beads crosslinked with calcium chloride (CaCl2). The maximum removal efficiency obtained was 92.29 +/- 0.51 % and 93.63 +/- 0.09 % for As(V), using beads of K7Pb and K7Pb + TY6 respectively, whereas for As (III), it was 91.71 +/- 0.51 % with TY6 and 93.35 +/- 0.05 % for KP7b + TY6, at pH 7 at 30 degrees C. Surface morphology was characterized by scanning electron microscopy and energy-dispersive x-ray analysis. This study revealed that the encapsulated bacteria immobilized on biochar were more effective than the free-cell and bacteria immobilized on biochar. It was also found that the beads could be reused effectively for five cycles (for K7Pb and TY6) and eight cycles (for K7Pb + TY6) before their removal efficiency reduced to below 80 %.