The model describes the anaerobiosis of 2-ethylhexanoic acid (2-EHA), which is a persistent and inhibitory organic waste. Model development was based on a biphasic degradation pathway mediated by three groups of bacteria. The model comprises seven equations with 13 constant parameters. The distinctive features include : 1. Grouping of anaerobic bacteria according to the metabolic functions; 2. Description of all essential reactions and mixed-culture interactions, namely interspecies H-2 and volatile fatty acid transfers; and 3. Correlation of 2-EHA inhibition with the concentration of unionized 2-EHA. The validated and fine-tuned model was applied to simulate substrate utilization, intermediate and product formations, and bacterial cell synthesis.