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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 concentrations of those ions in
waters which is an important source of contamination of the aquatic bodies, especially when it is considered that
such ions can be disseminated through the food chain
(Paim et al., 2003).
Heavy metal contamination exists in aqueous waste streams from diverse
industries, such as metal plating, mining, tanneries, painting, car radiator manufacturing,
batteries, as well as agricultural sources where fertilizers and fungicidal sprays are
intensively used. Copper (Cu), Zinc (Zn), Mercury (Hg) and Cadmium (Cd) are harmful
wastes produced by industries that pose a risk to the contamination of groundwater
and other water resources. Heavy metals are not biodegradable and tend to
accumulate in living organisms, causing various diseases and disorders (Friberg et al., 1974; Baik et al., 2002; Guo et al., 2002; Ngah et al., 2002; Matis et al., 2003; Yu, 2005; and Prasertet al., 2006). For example, Cd causes serious renal damage, anemia, hypertension
and itai -itai (a type of disease caused by Cd
contamination).
The reduction of pollutant to an acceptable level is necessary when toxic
metals are present in the aquatic system (Gupta et al., 2003). In this regard, several conventional wastewater treatment technologies, such as ion exchange,
chemical precipitation, evaporation, membrane filtration, reverse osmosis,
electrodialysis and adsorption were developed and used successfully. Application of
such traditional treatment techniques needs enormous cost and continuous input
of chemicals which becomes impracticable and uneconomical, and causes
further environment damage. |
