REMOVAL OF HEAVY-METALS FROM AQUEOUS-SOLUTIONS USING IMMOBILIZED FUNGAL BIOMASS IN CONTINUOUS-MODE

Fungal microorganisms are being increasingly studied for the removal o f heavy metal ions from aqueous solutions. The fungal biomass in powde red form is commonly used in metal adsorption studies. The use of powd ered biomass can pose problems in its application in batch and continu ous (column) type reactors treating wastewaters because fungal biomass becomes soft in contact with water, has low density, is difficult to separate from treated wastewater and fixed bed reactors using it can e asily clog. Immobilization of fungal biomass in a solid polymer matrix will facilitate their application in industrial systems treating heav y metal bearing wastewater. In this study, A. niger biomass was immobi lized in a polysulfone matrix. For this purpose an immobilizing unit w as fabricated to produce an immobilized biomass matrix of spherical sh ape. The beads were found to have a porous structure. Majority of the beads had particle sizes in the range of 2.00 to 0.841 mm. The biomass beads packed in a column were able to remove metal ions such as cadmi um, copper, lead and nickel. The breakthrough data obtained for cadmiu m, copper, lead and nickel was adequately described by the Thomas adso rption model. The amounts of metal adsorbed per unit weight of beads f or cadmium, copper, lead and nickel were 3.60, 2.89, 10.05, and 1.08 m g/g respectively. The adsorbed metal ions were easily eluted from the column using 0.05N nitric acid. These beads may be easier to use in in dustrial wastewater treatment systems in comparison with the fungal bi omass powder. (C) 1998 Elsevier Science Ltd. All rights reserved.