A statistical approach for optimization of media components for phenol degradation by Alcaligenes faecalis using Plackett–Burman and response surface methodology

ABSTRACT

In the present study, phenol degrading bacterial species was isolated from coke oven wastewater of Durgapur steel plant, India. The biochemical, morphological, and 16s rDNA study were performed to identify the isolated microbes. The studies revealed that the high concentration phenol (2,100 mg L⁻¹) degrading isolating microbe is Alcaligenes faecalis. Optimization of media components and incubation time for phenol degradation was carried out by two-step statistical approach. Six key determinants such as phosphate, iron sulfate, calcium chloride, magnesium chloride, ammonium sulfate concentrations, and incubation time were screened using Plackett–Burman design and were further optimized by response surface methodology (RSM) using practical central composite design. The experimental results of the RSM were fitted via a second-order polynomial regression equation having the correlation coefficient (R ²) 0.9998 that indicates appropriate predictions of the above variables for significant phenol degradation. The results showed that there was 100% phenol degradation of 2100 mg/L which could be achieved at the optimized media composition as analyzed from RSM to appreciate the efficiency of the process using composition 0.42 g L⁻¹ phosphate, 0.46 g L⁻¹ iron sulfate, 0.08 g L⁻¹ calcium chloride, 0.18 g L⁻¹ magnesium chloride, and ammonium sulfate 0.25 g L⁻¹ and 90.8 h incubation time.

Keywords:

• Modeling
• Response surface methodology
• Plackett–Burman design
• Optimization
• Fermentation
• Biodegradation