Modeling and simulation for degradation of different polyaromatic sulfur heterocyclic compounds by bacillus sphaericus HN1 in a batch reactor

Abstract EN

Biodegradation kinetics of different polyaromatic sulfur heterocyclic compounds (PASHs) ; thiophene (Th), benzothiophene (BT), dibenzothiophene (DBT), 4-methydibenzothiophene (4-MDBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) with different initial concentrations range So of (100–1000 mg / L) employing suspended cultures of Bacillus sphaericus HN1 with initial concentrations Xo range of (291.90 – 362.01 mg / L dry weight) in a series of batch experiments were investigated.

A mathematical model was predicted to describe biodegradation kinetics of the studied PASHs using HN1.

The predicted model is based on Haldane biokinetic equation for substrate inhibition which is applied to describe the dependence of specific growth rate μ (h-1) on So.

Haldane equation seems to be an adequate expression for the cell growth data, and the biokinetic constants obtained were; maximum specific growth rate (h-1) μmax = 0.165, 0.231, 2.461, 0.207 and 0.202 for Th, BT, DBT, 4-MDBT and 4,6-DMDBT, respectively, the saturation constant (mg / L) Ks = 3.007, 18.425, 2004.25, 42.25 and 103.43 for Th, BT, DBT, 4-MDBT and 4,6-DMDBT, respectively, while the inhibition constant (mg/L) Ki = 2110.42, 1752.42, 46.849, 2242 and 360.61 for Th, BT, DBT, 4-MDBT and 4,6-DMDBT, respectively.

The predicted model simulation curves for bacterial growth X (mg/L dry weight) and substrate concentration S (mg / L) are derived by solving simultaneously the resulting ordinary differential equations (ODEs).

The calculated values from the predicted model were compared with experimental data and indicated that the predicted model satisfactorily describes the trend of experimental results.