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D. Brahma and D. Dutta
human eyes and skin upon chronic exposure. Due to its several negative impacts on
the ecosystem it is banned worldwide since 2006 by Food and Drug administration,
United States. But MG is still used in some of the industries due to the unavailability
of cheap substitute (Daneshvar et al. 2007; Bera et al. 2016; Wu et al. 2018; Lv et al.
2013). Hence, removal of MG from industrial effluent by an economically feasible
method is necessary to reduce the harmful effects of MG contamination. Biological
method for dye removal has gained more attention over several physical and chemical
methods due to inexpensive, highly specific, and ecologically friendly nature (Srinivasan and Viraraghavan 2010). Biosorption process has several advantages over other
conventional treatment methods like low capital investment, inexpensive, low operational cost, high efficiency, production of biological or chemical sludge is less, etc.
(Wang et al. 2015). In recent years biosorption using micro-organisms were mostly
employed for removal of contaminants due to low cost, availability in large quantities,
and high efficiency nature. Among the micro-organisms bacteria could make excellent biosorbent for dye removal due to their high surface to volume ratio, high content
of potential active sites, high abundance, and diverse nature. Batch operations are
frequently applied for dye removal study (Volesky 2007; Parmar and Shukla 2018).
Column study was performed to understand the applicability of adsorbent in dye
removal. Free cells are not suitable to be used in column due to its low size, density,
and tendency to plug the column (Pons and Fuste 1993). Immobilization of cells in
support matrix offers advantages such as increased stability, reduced cell loss, easier
solid–liquid separation, and allows more efficient utilization of the capacity of adsorbent (Adhikari et al. 2012; Bayat et al. 2015). Recently, more research is focused on
the application of live microbial biomass for wastewater treatments because they do
not require pre-treatments which further save operational costs (Parmar and Shukla
2018).
In our study, we aimed to effectively decolorize malachite green dye by using
Kocuria marina DAGII cells in continuous mode. Spectrophotometric analysis was
carried out to know the process of dye removal. Column study was performed at
different operating conditions using immobilized K. marina DAGII cells as packing
material. Screening and optimization of physical parameters were done by Response
Surface Methodology to obtain maximum removal.
2 Materials and Methods
2.1 Microorganism and Chemicals
The gram positive bacterial strain K. marina DAGII was isolated from the soil of
NIT Durgapur, West Bengal. Growth of bacterium was done as described (Mitra
et al. 2015). The strain was aerobically maintained in brain heart infusion (BHI)
agar slants for regular use by subculture method and stored at 4 °C for further use.
Inoculum was prepared as described (Mitra et al. 2016, 2017). All the chemicals
D. Brahma and D. Dutta
human eyes and skin upon chronic exposure. Due to its several negative impacts on
the ecosystem it is banned worldwide since 2006 by Food and Drug administration,
United States. But MG is still used in some of the industries due to the unavailability
of cheap substitute (Daneshvar et al. 2007; Bera et al. 2016; Wu et al. 2018; Lv et al.
2013). Hence, removal of MG from industrial effluent by an economically feasible
method is necessary to reduce the harmful effects of MG contamination. Biological
method for dye removal has gained more attention over several physical and chemical
methods due to inexpensive, highly specific, and ecologically friendly nature (Srinivasan and Viraraghavan 2010). Biosorption process has several advantages over other
conventional treatment methods like low capital investment, inexpensive, low operational cost, high efficiency, production of biological or chemical sludge is less, etc.
(Wang et al. 2015). In recent years biosorption using micro-organisms were mostly
employed for removal of contaminants due to low cost, availability in large quantities,
and high efficiency nature. Among the micro-organisms bacteria could make excellent biosorbent for dye removal due to their high surface to volume ratio, high content
of potential active sites, high abundance, and diverse nature. Batch operations are
frequently applied for dye removal study (Volesky 2007; Parmar and Shukla 2018).
Column study was performed to understand the applicability of adsorbent in dye
removal. Free cells are not suitable to be used in column due to its low size, density,
and tendency to plug the column (Pons and Fuste 1993). Immobilization of cells in
support matrix offers advantages such as increased stability, reduced cell loss, easier
solid–liquid separation, and allows more efficient utilization of the capacity of adsorbent (Adhikari et al. 2012; Bayat et al. 2015). Recently, more research is focused on
the application of live microbial biomass for wastewater treatments because they do
not require pre-treatments which further save operational costs (Parmar and Shukla
2018).
In our study, we aimed to effectively decolorize malachite green dye by using
Kocuria marina DAGII cells in continuous mode. Spectrophotometric analysis was
carried out to know the process of dye removal. Column study was performed at
different operating conditions using immobilized K. marina DAGII cells as packing
material. Screening and optimization of physical parameters were done by Response
Surface Methodology to obtain maximum removal.
2 Materials and Methods
2.1 Microorganism and Chemicals
The gram positive bacterial strain K. marina DAGII was isolated from the soil of
NIT Durgapur, West Bengal. Growth of bacterium was done as described (Mitra
et al. 2015). The strain was aerobically maintained in brain heart infusion (BHI)
agar slants for regular use by subculture method and stored at 4 °C for further use.
Inoculum was prepared as described (Mitra et al. 2016, 2017). All the chemicals