Detailed knowledge of the bacterial growth kinetics is essential to ensure optimized biodegewater at high volume processing. A potential azo-dye degrading bacterium (Bacillus subtilis M from the sludge-waste nearby carpet-dyeing unit at Bhadohi in Uttar Pradesterial strain was used to decolorize simulated wastewater containing Congo Red dye in a batch reactor. This study primarily aimed at developing a parametric bacterial growth model to account the decelerating bac