Metal removal studied by a laboratory scale immobilized microalgal reactor

A laboratory scale algal column reactor packed with 75 ml alginate-algal beads was used to treat 30 mg/L Cu and Ni with a HRT of 30 minutes. At the end of loading 4L metal solution, over 97% of Cu and 91% of Ni were removed from the wastewater with a final residual of 1.76 mg/L Cu and 8.8 mg/L Ni. Up-flow was preferred to down-flow in maintaining a constant flow rate and hence HRT. Amount of metal recovered during regeneration depended on concentration and nature of regenerant used. Dilute acid was a better regenerant than calcium in terms of metal recovered (90%) and volume needed for regeneration. The consistency in the metal removal performance by the algal column over 10 metal treatment and regeneration cycles suggested that the algal beads can treat Cu or Ni bearing wastewater over 400 times its own volume.