Analysis of Batch Kinetic Data of Biodecolorization Reaction: Theoretical Approach for the Design of Packed Bed Reactor

The degradation of azo dyes by conventional methods has proven ineffective due to their complex structure and synthetic nature. Bioremediation of azo dye containing textile wastewater requires an appropriate selection of potential strains to address its potential hazards. This study focuses on the biodegradation of azo dyes containing textile wastewater by isolating halotolerant bacterial strains from marine coastal soil. The rapid degradation of model dye Mordant Yellow 10 (MY10) was monitored spectrophotometrically and it was found that decolorization of MY10 by isolated strains Bacillus firmus (BA01), Pseudomonas aeroginosa (BRPO3), and Bacillus cereus (BRPO4) and mixed consortium CMBS follows zero-, second-, first-, and one-and-a-half-order kinetics, respectively. Through the batch kinetic analysis of MY10 degradation, it was observed that bacterial strain Pseudomonas aeroginosa BRPO3 was more effective with reaction rate constant and half-life as $\mathrm{1,024}\pm 213\times {10}^{-2}{\mathrm{mM}}^{-1}{\mathrm{day}}^{-1}$ and $0.3\pm 0.1\mathrm{day}$, respectively. Further kinetic analysis using BRPO3 helps describe that initial dye and glucose concentration were the driving forces of the dye degradation reaction and thus were used to construct kinetic rate equation. Using a stepwise protocol, this kinetic model was applied to calculate the design parameters including optimal height and working volume of an upflow anaerobic packed bed (UAPB) reactor as 0.95 m and 4.78 L, respectively, for 85% dye conversion. Design was validated by evaluating the performance of the newly fabricated UAPB reactor for treatment of simulated wastewater containing MY10 and real textile wastewater. Complete dye removal and 94.5% total organic carbon (TOC) reduction were observed with simulated wastewater, whereas in real textile effluent 82.5% dye removal and 89% TOC reduction were achieved. Thus, the predicted results corresponded satisfactorily with the experimental data in both wastewater treatments. This study highlights the usefulness of analyzing biodegradation kinetics to improve both the construction of microbial consortia and the development of reactors for wastewater treatments in the context of bioeconomy.