Modeling and Simulation for Biodegradation of Mono-, Binary-, and Tertiary-substrate Batch Systems of Different Polyaromatic Sulfur Heterocyclic Compounds

Abstract

Biodegradation kinetics of different polyaromatic sulfur heterocyclic compounds (PASHs): thiophene (Th), benzothiophene (BT), and dibenzothiophene (DBT) in a series of batch experiments were investigated as mono-, binary-, and tertiary-substrate systems to study the substrates interaction effect and capabilities of Bacillus sphaericus HN1 to utilize PASHs as sole carbon and energy source in mono- and multi-substrate systems. A multiple comparison test was performed for growth of microorganism and substrate biodegradation to obtain pairwise comparison between the three studied systems. Both tests ANOVA1 and Kruskal-Wallis showed that there was a highly statistically significant difference in growth of HN1 between negative control (free of PASHs) and all other treatments (p = 2.2105e-7 and 9.303e-4, respectively). Although, there was a statistically significant difference for biodegradation of DBT in mono– and binary-substrate systems within the time interval 96–168 h (p < 0.05), but there was a nonstatistically significant difference in the biodegradation of both Th and BT in the three studied systems (p > 0.05). A multi-substrate form of the Monod kinetic model was applied to predict the substrate interactions in binary- and tertiary-substrate systems using the Monod parameters derived from the mono-substrate systems. Simulation of the applied models to describe and estimate the biodegradation kinetics of the three studied PASHs in the different investigated systems was performed and the validity of the models was confirmed.

Keywords:

• biodegradation kinetics
• polyaromatic sulfur heterocyclic compounds PASHs
• multi-substrate system
• Bacillus sphaericus HN1
• modeling and simulation