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

Area of Science:

• Environmental microbiology
• Bioremediation technologies
• Wastewater treatment

Background:

• Textile wastewater containing synthetic dyes like malachite green (MG) poses significant environmental risks.
• Limited research exists on using Shewanella putrefaciens immobilized on polyurethane foam (PUF) in fixed-bed bioreactors (FBBRs) for MG dye removal.
• The stability and performance of such FBBRs for mixed dye and municipal wastewater decontamination require further investigation.

Purpose of the Study:

• To evaluate the stability and performance of an FBBR using Shewanella putrefaciens immobilized in a polyurethane foam matrix for decontaminating a mixture of MG dye and municipal wastewater.
• To optimize process variables (pH, retention time, dye concentration) for maximum dye and chemical oxygen demand (COD) removal.
• To assess the biodegradation mechanism and operational stability of the developed biocatalyst.

Main Methods:

• Immobilization of Shewanella putrefaciens in a polyurethane foam matrix coated with calcium alginate.
• Optimization of process parameters (pH, retention time, initial dye concentration) using a central composite design within a lab-scale fixed-bed bioreactor.
• Analysis of biodegradation using Fourier transform infrared spectroscopy (FTIR).
• Predictive modeling using artificial neural network (ANN) analysis.

Main Results:

• Optimized conditions (pH 7.10, 18.0 h retention time, 240 mg/L initial dye concentration) yielded maximum removal efficiencies of 91.42% for MG dye and 88.27% for COD.
• Artificial neural network analysis demonstrated high reliability in predicting bioreactor performance.
• FTIR analysis confirmed structural changes in the MG dye, indicating biodegradation.
• The biocatalyst exhibited reasonable operational stability, biodegradability, and tolerance in the dye-laden environment.

Conclusions:

• The developed Shewanella putrefaciens-immobilized bioreactor is a promising technology for degrading malachite green dye and managing textile and municipal wastewater.
• The study provides a foundation for scaling up this bioremediation approach for industrial applications.
• The optimization and predictive modeling enhance the understanding and potential application of microbial consortia in wastewater treatment.