Process optimization for effective bio-decolourization of methyl orange by Pseudomonas aeruginosa 23N1 using chemometric methodology

Abstract

Development of low-cost and efficient treatment processes to remove dyes from dye-laden industrial wastewaters is currently an important topic of research. This study aims to investigate the bio-decolouration of methyl orange (MO) dye by Pseudomonas aeruginosa 23N1 and to optimize the process parameters for efficient removal of MO. The regular two-level factorial analysis technique is used to screen out the operational factors and to select their upper and lower limits for further optimization using central composite design (CCD). The result revealed that the peptone, yeast extract, and salt are the vital nutrients required by the bacteria to achieve high dye decolourization. Analysis of variance (ANOVA) in CCD indicates (correlation coefficient (R2) as 0.999 with predicted Rpre2 = 0.996 and adjusted Radj2 = 0.998) a strong correlation between the predicted response and the experimental response under identical experimental conditions. ANOVA in CCD exhibits high positive coefficients of estimate, 21.86 and 17.75, for dye and yeast extract concentration, respectively, suggests their major influences on decolourization performance. Higher decolourization is achieved at higher initial dye concentration due to the utilization of dye molecules as a preferable food supplement for bacteria. Model validation analyses show 98.23 ±0.4 %, and 98.60 ±0.5 % decolourization for initial 50 and 150 mg/L dye solution, respectively, which are in agreement with the model predicted dye decolourization percentages of 98.44 and 98.34 %, respectively. The disappearance of the maximum absorption peak of the MO dye in the UV-visible spectra indicates that decolourization of dye is either through the bioaccumulation or biodegradation mechanism. © 2018 Canadian Society for Chemical Engineering