Mineral operating industries such as mining, electronic
device manufacturing, and metal plating were
often faced with the problem of eliminating or treating
waste water streams which were contaminated with low
levels of heavy metal ions including copper, cadmium,
zinc, and lead (Gilles and Loehr, 1994). Since many
heavy metals are highly toxic even at low concentrations
and not biodegradable, they must be removed from the
polluted streams in response to growing environmental
legislation and enforcement. In addition, groundwater
often contains iron and manganese, which cannot only
affect the flavor and color of water but also accumulate
to cause obstruction in the water equipment and pipelines.
Conventional methods employed to remove heavy
metals contained in water streams include chemical precipitation,
filtration, electrodialysis, and ion exchange.
However, electrodialysis and ion exchange plants have
high maintenance and operation costs. Chemical precipitation
is inexpensive but incapable of removing trace
levels of heavy metal ions.
Adsorption is expected to overcome such impediments,
having a wide variety of applications. Of many
sorbents, utilization of naturally occurring materials has
been recognized as a way of reducing waste treatment
cost (Bailey et al., 1999). Alginate, which is a polysaccharide
biopolymer composed of varying compositions
of b-1,4 linked D-mannurinic and L-guluronic acids