TABLE OF CONTENTS Certain natural materials of biological origin can retain large quantities of metal ions by one of the different possible mechanisms including sorption and complexation. The biological material of such properties is called biomass and the phenomenon is called biosorption. It has been exploited for the separation and recovery of metals from effluents as well as for toxicity removal. This chapter will describe the sources of biomass, possible mechanisms of metal uptake and their potential in metal recovery from metallurgical effluents. Specific applications will be described in Chapters 7 10.
An economical source of biomass for the production of biosorbents is spent biomass from a fermentation process for manufacturing of biochemical products like antibiotics, enzymes, organic acids and possibly vitamins. This material, however, contains extraneous insoluble matter like the medium components or product recovery chemicals, which do not participate in biosorption. Even with such drawback, the spent biomass is far more cost effective than production of designed fermentation to produce biomass specifically for biosorption purposes. Conversion of a "waste" biomass to a biosorption agent also results in reclaiming the biomass material that would otherwise be disposed off as a waste. This is done by appropriate treatment procedures.
An abundant source of mixed microbial biomass is the activated sludge (AS) wastewater treatment process. The ability of AS biomass to remove and accumulate heavy metals has been known for many years. In a sewage treatment facility, metals such as Cd, Cu, Cr, Mg and Pb are removed largely...
