The Process Optimization During Biodegradation of Textile Dye in a Fixed-Bed Bioreactor Using Immobilized Shewanella...

The textile wastewater containing refractory and tenacious synthetic dyes poses a greater threat and hazardous impact on both terrestrial animals and plants. A limited analysis has been reported on the utilization of Shewanella putrefaciens-immobilized PUF for malachite green (MG) dye in a lab-scale fixed-bed bioreactor (FBBR). Furthermore, the present study focused on the stability and performance of the FBBR for decontaminating a mixture of MG dye and municipal wastewater. In this direction, S. putrefaciens species entrapped in a polyurethane foam matrix coated with calcium alginate was utilized. The efficacy of the biocatalyst was investigated by optimizing process variables, including pH (4.0-9.0), retention time (RT) (6.0-18.0 h), and dye concentration (60-240 mg/L). The central composite design of the response surface methodology-based optimization tool predicts the maximum dye and chemical oxygen demand removal of 91.42% and 88.27%, respectively, at a pH of 7.10, RT of 18.0 h, and an initial dye concentration of 240 mg/L. Furthermore, the predictability of the process responses was explored using artificial neural network analysis, which provided higher reliability in predicting bioreactor behavior. The detection and disappearance of several peaks by Fourier transform infrared spectroscopy analysis indicated that a structural change of the chemical bond occurred during the biodegradation of MG dye. Notably, on a comparison note, the present technique offered a reasonable operational stability, biodegradability, and tolerance ability in dye environment. Therefore, the present technique may serve as a potential approach for future development of large-scale models to degrade and manage textile and municipal wastewater.