Screening of various types biomass for removal and recovery of heavy metals (Zn, Cu, Ni) by biosorption, sedimentation and desorption

The increasing awareness of accumulation of heavy metals in the environment has led to a quest for new and improved "clean" technologies. In this regard, an innovative heavy metal removal process composed of biosorption, sedimentation and electrolysis was developed. This study covers the comparison of various types of waste biomass including bacteria (S.rimosus), yeast (S.cerevisiae), fungi (P.chrysogenum) and activated sludge as well as marine algae (F.vesiculosus and A.nodosum), for their efficacy in the biosorption, sedimentation and desorption stages in the removal of zinc, copper and nickel ions. In the biosorption studies carried out with single metal solutions, A.nodosum, S.rimosus and F.vesiculosus proved to be the best biosorbents for zinc, copper and nickel ions respectively. In ternary metal solutions, the presence of other metal ions affected the biosorption efficiency. S.rimosus, however, exhibited high specificity for Cu and A.nodosum roughly retained its metal uptake for all of the metal ions. The sedimentation efficiencies were found to be proportional to the biosorption efficiencies. Desorptions were not effective, hence recycling did not yield good results. Overall, among the biomass tested, A.nodosum, S.rimosus, F.vesiculosus and P.chrysogenum were found to have the highest potential for use in the heavy metal removal process. (C) 1998 Published by Elsevier Science Ltd. All rights reserved