Removal of Heavy metal by Biological Method Seung-yun Yang Block-copolymer self-assembly center

Contents Introduction -Heavy metal (Source, Discharge limit, Health effect) -Conventional removal method (Non-biotic, Biotic) Research paper -Biosorption mechanism -Results Summary

 Solid and semisolid wastes Smelted ores, refining slags or sludges Processing or manufacturing scrap Spent catalysts or batteries WWT process sludges Introduction – The source of heavy metal pollution  Liquid wastes Electroplating, etching Smelting, refining Ore or coal mine drainage Other chemical process Electronic deviceMine

MetalsConcern Ba Long term – increased blood pressure and nerve block Cd A carcinogen. Soluble compounds of Cd are highly toxic. Long term – concentrates in the liver, kidneys, bone (osteomalacia) Cr Cr 6+ compounds are carcinogenic and corrosive tissue. Long term – skin sensitization and kidney damage. Pb Long term -- brain and kidney damage; birth defects Hg paralysis of body, sight trouble Long term – toxic to central nerve system; may cause birth defects Ag Long term – permanent grey discoloration of skin, eyes and mucus membranes. Introduction – Health effect of heavy metal

Example of heavy metal pollution Minamata disease (Hg)Itai itai disease (Cd)

Compound CN - FeZnCuCdHg Upper limit Compound AsPbCr 6+ MnF P Upper limit Unit: mg/L (ppm) Introduction – Effluent standard of waste water  Increased concerns on health and environment  Effluent standard becomes more strict It is necessary to treat wastewater containing low conc. of heavy metals.

Introduction - Conventional removal process Non-biotic method  Precipitation  Membrane (Ultrafiltration, Reverse osmosis)  Ion-exchange  Absorbent (Activated carbon, cellulose, polymer) Biotic method  Biomass materials (Alga, fungus, bacteria)

 Precipitation Transforms dissolved contaminants into an insoluble solid Use pH adjustment, addition of a chemical precipitant, and flocculation Low removal efficiency, Production of sludges  Ion exchange Reversible chemical reaction Recovery and reuse of desired products Expensive (resin), low chemical resistance  Membrane process Separate heavy metal from waste water by size effect Improper to high loading, High installation and operation cost Conventional removal process – Non-biotic method

Conventional removal process – Biological method  Bioaccumulation metabolically driven active accumulation by living cells  Biosorption a property of inactive, dead, microbial biomass to bind and concentrate heavy metals outsideinside Meta l Biomass

Biosorbent uptake of metals by microbial biomass Metals can be accumulated more than 30% of biomass weight in Some species (Ascophyllum and Sargassum)

Biosorbent uptake of metals (continued) Biosorbent material Ubiquitous Cheap Abundant

 Complexation Complex formation between metal ion and functional groups Metal ions bind with ligands in biomass through chelation  Physical adsorption Interactions between metal and functional groups of cell surface (carboxylate, hydroxyl, sulfates, phosphate, amino acid etc..) non-metabolic dependent, rapid, reversible Biological method – Biosorption mechanism  Uptake process 1st step : independent metabolism binding to cell walls 2nd step : transport across the cell membrane by metabolism

Research paper Mucor rouxii - Representative soil fungus - A lot of functional group ( The amino, carboxyl, and sulfury groups present in fungal cells play an important role in metal binding ) Heavy-metal removal from aqueous solution by fungus Mucor rouxii G. Yan, T. Viraraghavan, Water Res (2003)

Experimental Pb +2, Cd +2, Ni +2, Zn +2 : 75ml (conc. : 10 PPM) Biomass(live or dead) : 0.05g (Pretreated by NaOH) Atomic absorption (AA) spectrometer 0.45  m filter Shaking at 125 rpm

Result I – Effect of pH on biosorption The pH plays an important role mainly by its influence on metal or cell wall chemistry.

Result II – Metabolic effect on removal of heavy metal Some portion adsorbed in live biomass was used for metabolic reaction by intracellular uptake

Result III – Desorption of metal ions from M. rouxii Efficiency of desoption of heavy-metal ions biosorbed in biomass can be controlled by elutant up to 90 %.

Summary Biological method can be utilized for removal of heavy metal High efficiency of removal (up to 30% of biomass) Abundance of biosorbent Mucor rouxii biomass showed a high adsorption capability for the heavy metal removal. - pH plays an important role on metal or cell wall chemistry - Metabolic as well as non-metabolic reaction involved in removal of heavy metal - High recovery of biosorbed metal ions could be achieved with acid elution

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