Environmental Engineering Reference
In-Depth Information
such as wool, silk and polyamide. However, these pigments are seriously de
cient
in fastness properties, especially in relation to washing and light. Consequently, the
use of TPM dyes in the textile industry has decreased signi
cantly, since dye from
other classes became available. At present, the photographical, food, cosmetic, and
stationary industries seem to be the major consumers of this group of chemicals
(Thetford 2000 ). TPM dyes are also extensively used in medicine and experimental
biology (e.g. in cytology, histology, microbiology) to stain cells and proteins
(Altikatoglu and Celebi 2011 ). Due to antibacterial, antifungal and antiprotozoal
properties, several TPM dyes serve as medical disinfectants (Srivastava et al. 2004 ;
Casas et al. 2009 ; Hashimoto et al. 2011 ). For example, Malachite green has been
used since 1933 as a medicine for
sh infected by fungi (Saprolegnia sp., Apha-
nomyces sp., Haliphthoros sp.) and protozoa (Trichodina sp., Trichodinella sp.,
Chilodonella sp.) (Srivastava et al. 2004 ; Hashimoto et al. 2011 ). Nevertheless,
Malachite green is pointed out as a highly controversial compound due to the risk it
poses to the consumers of the treated
shes. Malachite green and some of its
metabolites have been reported to induce human carcinogenesis and mutagenesis
(Sudova et al. 2007 ). Several studies have shown that exposure to this dye increases
the risk of chromosomal fractures, reduces fertility and may also cause inhibition of
respiratory enzymes (Srivastava et al. 2004 ; Stammati et al. 2005 ; Culp et al. 2006 ).
Therefore, the use of Malachite green in aquaculture has been banned since 2000 in
the European Union and in the United States of America and Canada since 2005
(Andersen et al. 2009 ). Similarly, Crystal violet, known as Gentian violet or Methyl
violet 10B, is applied in human and veterinary medication as an antifungal agent for
dermatological infections, treatment of pinworms and some tropical diseases (Casas
et al. 2009 ). It has been also found to bind to DNA and thus causes replication
errors (Ayed et al. 2009 ). The characteristics of TPM dyes, most frequently used in
recent biological studies, are presented in Table 1 .
2 Microbial Treatment of Waste Water Containing Dyes
As a consequence of many applications and accumulation ability, TPM dyes are
commonly present in wastewater and hence pollute aquatic environments. For the
removal of synthetic dyes from water bodies a wide range of physical, chemical and
biological methods have been developed (Crini 2006 ; Ali 2010 ; Verma et al. 2012 ).
Although chemical and physical decolorization techniques (e.g. adsorption, pre-
cipitation, coagulation,
ltration, electrolysis, photodegradation and chemical oxi-
dation) are effective for color removal, they have serious constraints, such as high
cost, low ef
ciency, limited versatility, interference with other wastewater con-
stituents, formation of hazardous metabolites and intensive energy requirements
(Kaushik and Malik 2009 ). Therefore, there is an increasing interest in exploring
the mechanisms of bioremoval of TPM dyes from wastewater which will be proven
very effective and environment friendly methods (dos Santos et al. 2007 ; Sarayu
and Sandhya 2012 ).
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