Environmental Engineering Reference
In-Depth Information
For example, removal of Acid Navy Blue by A. lentulus pre dominantly followed
bioaccumulation mechanism, while biosorption played a minor role (Kaushik and
Malik 2010 , 2013 ). Also, each mechanism i.e. biosorption, bioaccumulation or
biodegradation, has its own advantages and limitations. Therefore, it is always
bene
cial to use a consortium of microbes for such treatment processes over pure
cultures, as it promotes the dye removal process through multiple mechanisms,
making it more ef
cient in terms of percentage removal, time required and sup-
plementation needs.
3 Analytical Tools to Study Dye Removal Process
Monitoring ofdye removal process is based on the study of dye concentration at a
given time or by estimating the production ofmetabolites/intermediates or dye by
products. Dye concentration can be estimated through various measurements, such
as Total Organic Carbon (TOC), Chemical Oxygen Demand (COD) or by mea-
suring absorbance of the solution at the absorption maxima of the dye with a UV-
Vis spectrometer. However, these techniques are not selective in nature and affected
by other contaminants that may be present in the solution. More speci
c analytical
techniques have been used by the researchers to monitor thedye removal process as
well as to determine the dye intermediates that are released as a result of degra-
dation process. The choice of analytical technique depends on the type of dye
removal process involved and type of the dye. These analytical techniques can be
categorized into two types: separation techniques and spectroscopic techniques.
Separation techniques include various chromatographic techniques, such as High
Performance Liquid Chromatography (HPLC), Gas Chromatography Mass Spec-
trometry (GCMS), Liquid Chromatography Mass Spectrometry (LCMS), High
Performance Thin Layer Chromatography (HPTLC) etc. which help in the identi-
cation of the intermediate compounds released during the dye removal process as
well as the
nal degradation products formed as a result of biodegradation. Spec-
troscopic techniques, such as UV-Vis spectroscopy, have been widely used by the
researchers to quantify the dye removal process in terms of reduction brought about
in the absorbance value (at absorption maxima) of the dye. In addition to this,
Fourier Transform Infra-Red Spectroscopy (FTIR) and Nuclear magnetic Reso-
nance (NMR) have also been utilized as an essential tool for estimating the dye
degradation pathway. A recent review by Fern
ndez et al. ( 2010 ) has listed the
advantages and limitations of these two types of analytical techniques in Table 3 .
Apart from these techniques,enzymatic assays, that involve the detection of
various dye degrading enzymes, have been used by the researchers to con
รก
rm
biodegradation process during dye removal. Various white-rot fungi, such as
Trametes versicolor, Phanerochaete chrysosporium, Pleurotus ostreatus etc., have
been reported to produceextracellular ligninolytic enzymes, such as lignin peroxi-
dase (LiP), laccase, manganese peroxidase (MnP) etc. which cause dye degradation.
The assay to detect
the presence of an enzyme is based on either of
the
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