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Industrial activities represent an important pollutant source nowadays, mainly
concerning the addition of heavy metals in the soil. This contributes to a significant
increase in the concentration of those ions in waters representing an important
source of contamination of aquatic bodies, especially when it is considered that
such ions can be disseminated through the food chain (OECD, 1996).
Cadmium (Cd)(II) is a metal widely used in industries such as metal plating,
metallurgical alloying, mining, ceramics and other industrial operations (ATSDR,
1997). (Cd)(II) toxicity may be observed in a variety of syndromes and effects
including renal dysfunction, hypertension, hepatic injury, lung damage and
teratogenic effects (Owens, 1994). Hence it is important to remove trace of (Cd)(II)
from drinking water, or to remove cadmium from waste waters before they are
The IUP Journal of Chemical Engineering, Vol. III, No. 2, 26 2011
discharged into receiving water bodies. The conventional methods for treatment
of Cd(II) in wastewater include: precipitation, adsorption with activated carbon,
ion exchange, membrane processes, oxidation and reduction (Matheickal and Yu,
1996; and Martins et al., 2004).
These methods are expensive and often involve the use of chemicals and
generate large amounts of sludge. Biosorption is a process that utilizes low-cost
biosorbents to sequester toxic heavy metals (Chang and Hong, 1994). The
advantages of biosorption over the conventional methods are low operating cost,
selectivity for specific metal, short operational time and no chemical sludge
(Chu et al., 1997). |
