Heavy metal sorption by marine algae and algal by-products

All the oceans are plentiful with marine algae. Non-viable marine macroalgae are able to adsorb heavy metal ions. Compared with other biosorbents, such as fungi, bacteria, yeasts and microalgae, they have the advantage of being easily available, cheap and having high heavy metal sorption capacities. The by-products of marine phaeophyceae are even more cost-effective heavy metal biosorbers. Experiments of heavy metal sorption using non-viable Fucus vesiculosus, Ascophyllum nodosum and algal by-products were carried out to investigate the factors influencing and optimizing the heavy metal biosorption. The pH value, biomass concentration, heavy metal concentration, heavy metal species, competing ions, algal varieties and time were the most decisive parameters. The sorption isotherms showed increasing sorption capacities and decreasing sorption efficiencies with an increase in the initial heavy metal concentration. Sorption kinetics of different metals were established. Biomass concentration influenced the sorption efficiencies very much, but reduced the sorption capacity per g biomass. The pH value controlled the sorption (pH 3-7) and desorption (pH 1-2) decisively. Beside heavy metal contaminated model waters, actual industrial effluents were treated successfully by algal sorbents in batch experiments and continuous column tests. Transmission electron micrographs of different contaminated and untreated algal specimens are available.