Process Safety and Environmental Protection, Vol.131, 116-126, 2019
Enhanced decolorization of reactive violet dye 1 by halo-alkaliphilic Nesterenkonia strain: Process optimization, short acclimatization and reusability analysis in batch cycles
The study explores the efficacy of indigenously isolated halo-alkaliphilic bacterium Nesterenkonia sp. for decolorization of reactive violet 1(RV1) dye at alkaline pH. Dye decolorization by the microbe was tested first in nutrient broth by varying initial dye concentration (50-3000 mg/L), pH (7.0-12.0), inoculum size (1-10%) and temperature (4-45 degrees C) by spectrometric determination of absorbance at 550 nm, using single parameter approach. Box Behnken Design model of Response Surface Methodology (RSM) was then used to obtain optimized combination of process parameters for best dye degrading response of the microbe, based on 46 experiments. The microbe is found effective under a wide range of conditions and showed excellent reusability up to 6 batch cycles. Short term acclimatization in repeated cycles made decolorization faster and greater. Growth of the microbe was favored at high pH (11.5) and in the presence of salts (2.5-5%), decolorizing 94-100% of the dye. Decolorization of the dye by the microbe was also studied in simulated and real textile wastewaters under the optimized process conditions using 1% starch as carbon supplement. The bacterium degraded the dye and also bioremediated the wastewaters by successfully moderating the pH, removing toxic metal Cr (VI) and chemical oxygen demand (COD) during treatment. (C) 2019 Published by Elsevier B.V. on behalf of Institution of Chemical Engineers.