Chandra (2004) successfully treated PMDE in two-stage treatment process involving
the transformation of recalcitrant coloring components of the PMDE by aerobic
bacterium B. thuringiensis followed by a subsequent decline of a remaining load of
pollutants by a macrophyte Spirodela polyrrhiza Schleiden. A similar biphasic (two
steps) treatment of the PMDE was carried out in a CW with B. thuringiensis
followed by T. angustata L. by Chandra et al. (2008) which resulted in 98–99%
COD, BOD, and color reduction after 7 days. The results suggested that the bacterial
pre-treatment of PMDE integrated with CW will improve the treatment process of
PMDE and promote safe disposal of hazardous distillery waste. Chandra et al.
(2012) reported 96.0% and 94.5% reduction in COD and BOD values in two-step
sequential treatment of PMDE by bacteria and wetland plant Phragmites communis.
He also characterized rhizosphere bacterial communities of P. communis and metabolic products generated during the sequential treatment of PMDE in CW plant
treatment system. A two-step sequential treatment for sugarcane molasses-based
anaerobically treated distillery effluent was reported by Pant and Adholeya (2009a).
In the first step, distillery effluent was treated in a hydroponic-based system using
two plant species, namely, Vetiveria zizanioides and P. karka to reduce (up to 84%)
the high nitrogen content of the effluent. This first-step hydroponically treated
distillery effluent was subjected for treatment by two fungus species in a bioreactor.
Decolorization of effluent up to 86.33% was obtained with Pleurotus florida Eger
EM1303 followed by Aspergillus flavus TERIDB9 (74.67%) with a significant
reduction in COD as well. This study recommended that distillery effluent treatment
without the need of high dilutions and addition of supplementary carbon sources.
The efficacy of the two-step treatment approach has been demonstrated under pilot
scale. For organic in-contaminants present in wastewater, this approach found to be
effective in the field scale, and it is likely during the next 5–10 years, its use will
become widespread.
9 Challenges and Future Prospects
The major challenges of PMDE are the removal of TDS and degradation of colorcontributing compounds like melanoidin, polyphenols, caramel, an alkaline degradation product of hexose (ADPH), and their metabolic products as well as inorganic
compounds before its safe disposal into the environment. Different amino acids,
polysaccharide, and other organic compounds react at various extents; the polymerization most likely occurs in complex ways and extends to diverse levels. Accordingly, it is not easy to characterize those pigments responsible for color in distillery
effluent. It should also be highlighted that several colorants instead of one type of
pigment alone may result in the undesirable color, which will then enhance the
difficulties of decolorization and degradation of organic pollutant present in distillery effluent. It is reported that conventional biological treatment processes are
capable of accomplishing the reduction of ADPH, caramels, and melanoidins up
to 70% and 67%, respectively (Mohana et al. 2009). However, the low MW
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V. Kumar and R. Chandra
the transformation of recalcitrant coloring components of the PMDE by aerobic
bacterium B. thuringiensis followed by a subsequent decline of a remaining load of
pollutants by a macrophyte Spirodela polyrrhiza Schleiden. A similar biphasic (two
steps) treatment of the PMDE was carried out in a CW with B. thuringiensis
followed by T. angustata L. by Chandra et al. (2008) which resulted in 98–99%
COD, BOD, and color reduction after 7 days. The results suggested that the bacterial
pre-treatment of PMDE integrated with CW will improve the treatment process of
PMDE and promote safe disposal of hazardous distillery waste. Chandra et al.
(2012) reported 96.0% and 94.5% reduction in COD and BOD values in two-step
sequential treatment of PMDE by bacteria and wetland plant Phragmites communis.
He also characterized rhizosphere bacterial communities of P. communis and metabolic products generated during the sequential treatment of PMDE in CW plant
treatment system. A two-step sequential treatment for sugarcane molasses-based
anaerobically treated distillery effluent was reported by Pant and Adholeya (2009a).
In the first step, distillery effluent was treated in a hydroponic-based system using
two plant species, namely, Vetiveria zizanioides and P. karka to reduce (up to 84%)
the high nitrogen content of the effluent. This first-step hydroponically treated
distillery effluent was subjected for treatment by two fungus species in a bioreactor.
Decolorization of effluent up to 86.33% was obtained with Pleurotus florida Eger
EM1303 followed by Aspergillus flavus TERIDB9 (74.67%) with a significant
reduction in COD as well. This study recommended that distillery effluent treatment
without the need of high dilutions and addition of supplementary carbon sources.
The efficacy of the two-step treatment approach has been demonstrated under pilot
scale. For organic in-contaminants present in wastewater, this approach found to be
effective in the field scale, and it is likely during the next 5–10 years, its use will
become widespread.
9 Challenges and Future Prospects
The major challenges of PMDE are the removal of TDS and degradation of colorcontributing compounds like melanoidin, polyphenols, caramel, an alkaline degradation product of hexose (ADPH), and their metabolic products as well as inorganic
compounds before its safe disposal into the environment. Different amino acids,
polysaccharide, and other organic compounds react at various extents; the polymerization most likely occurs in complex ways and extends to diverse levels. Accordingly, it is not easy to characterize those pigments responsible for color in distillery
effluent. It should also be highlighted that several colorants instead of one type of
pigment alone may result in the undesirable color, which will then enhance the
difficulties of decolorization and degradation of organic pollutant present in distillery effluent. It is reported that conventional biological treatment processes are
capable of accomplishing the reduction of ADPH, caramels, and melanoidins up
to 70% and 67%, respectively (Mohana et al. 2009). However, the low MW
522
V. Kumar and R. Chandra