Bioreactor Design Guided by Kinetic Modeling: a Sustainable Approach for Catechol-Rich Industrial Wastewater Treatment

• B. pseudomycoides efficiently degrades Catechol up to 600 mg.L^-1.

• Growth and degradation follow the integrated Haldane model.

• Kinetic parameters guided design of a 10 L aerobic bioreactor.

• Provides eco-friendly strategy for pharmaceutical wastewater treatment.

Aerobic biodegradation of Catechol was investigated using the bacterial strain Bacillus pseudomycoides NBRC 101232, with an initial Catechol concentration of up to 600 mg·L^-1. The primary objective of this study was to evaluate the growth and degradation kinetics of the strain by monitoring biomass production and substrate depletion over time in a shake-flask batch reactor system. Microbial growth behavior was successfully described using the integrated Haldane substrate inhibition model, yielding kinetic parameters of μ_m = 0.056 h^-1, K_S = 28.52 mg·L^-1, and K_i = 126.50 mg·L^-1 at an initial Catechol concentration of 600 mg·L^-1. The average biomass yield coefficient (Y_X/S) was 0.0034 OD₆₀₀ units·L·mg^-1, indicating efficient substrate utilization under inhibitory conditions. The strain exhibited clear substrate inhibition kinetics at elevated Catechol concentrations. Based on the experimentally determined kinetic parameters and previously optimized physicochemical conditions, a preliminary aerobic continuous stirred-tank bioreactor (CSTR) design framework was developed for the treatment of Catechol-containing pharmaceutical wastewater. The integration of microbial kinetics with engineering design enables a rational framework for reactor sizing and operational optimization. This study provides a practical and scalable strategy for the efficient, sustainable, and eco-friendly biodegradation of high-strength Catechol-containing industrial wastewater.