Chitosan-based Materials in Waste Water Treatment––Recent Developments - Natural Polymers, Biopolymers, Biomaterials, and Their Composites, Blends, and IPNs - page 22

Chapter 3
Chitosan-based materials in Waste Water
treatment--recent developments
Hemlatha R., Shanmugapriya A., and Sudha P. N.
iNtroduCtioN
Contamination of aquatic media by metal ions is a serious environmental problem,
mainly due to the discarding of industrial wastes (Bose et al., 2002; Baraka et al.,
2007). Heavy metals are highly toxic even at low concentrations and can accumulate
in living organisms, causing several disorders and diseases (Aksu, 2005; Crini, 2006;
Forgacs et al., 2004). Metals can be distinguished from other toxic pollutants, since
they undergo chemical transformations, are non bio-degradable, and have great envi-
ronmental, economic, and public health impacts (Kozlowski and Walkowiak, 2002;
Rio and Delebarre, 2003).
tyPes oF treatmeNts
Heavy metals are not bio-degradable and tend to accumulate in living organisms, caus-
ing diseases and disorders (Vander Oost et al., 2003). The presence of heavy metals
in water should be controlled. Different technologies and processes are currently used
such as biological treatments (Pearce et al., 2003), membrane processes (Vander Bruggen
and Vandecasteele, 2003), advanced oxidation processes (F-Al Momani et al., 2002)
and adsorption procedures (Robinson et al., 2002) which are the most widely used
technologies for removing metals and organic compounds from industrial effluents.
Adsorption is now recognized as an effective, efficient and economic method for de-
contamination applications and separation analysis.
adsorption
The conventional methods such as chemical precipitation, oxidation, reduction, filtra-
tion, ion exchange, membrane separation, and adsorption (Mohan and Pittman, 2006).
Ion exchangers and membrane separation are relatively of very high cost (Nomanbhay
and Palanisam, 2005). Adsorption is the most frequently applied technique owing to
its advantages such as variety of adsorbents materials and high efficiency at a relative-
ly lower cost (Babel and Kurniawan, 2003). Although, activated carbon is one of the
most popular adsorbents for removal of metal ions, it is not supported now owing to
its high cost. Current investigations tend towards achieving high removal efficiencies
with much cheaper non-conventional materials which are mostly abundant in biologi-
cal matter.