Abstract:
Phenol is one of the main pollutants that have a serious impact on the environment and can even be very critical to human health.The biodegradation of phenol can be considered an increasingly important pollution control process. In this study, the degradation of phenolby Bacillus simplex was investigated for the first time under different growth conditions. Six different initial concentrations of phenol wereused as the primary substrate. Culture conditions had an important effect on these cells’ ability to biodegrade phenol. The best growth of thisorganism and its highest biodegradation level of phenol were noticed at pH 7, temperature 28C, and periods of 36 and 96 h, respectively.The GC-MS analysis of the bacterial culture sample revealed that further degradation of the catechol by 1,2-dioxygenase produce a cis,cis-mucconic acid via ortho-pathway and/or by 2,3-dioxygenase into 2-hydroxymucconic semialdehyde via meta-pathway. The highestbiodegradation rate was perceived at 700 mg/L initial phenol concentration. Approximately 90% of the phenol (700 mg / L) was removedin less than 96 hours of incubation time. It was found that the Haldane model best fitted the relationship between the specific growth rateand the initial phenol concentration, whereas the phenol biodegradation profiles with time could be adequately described by the modifiedGompertz model. The obtained parameters from the Haldane equation are: 1.05 h1, 9.14 ppm, and 329 ppm for Haldane’s maximumspecific growth rate, the half-saturation coefficient, and the Haldane’s growth kinetics inhibition coefficient, respectively. The Haldaneequation fitted the experimental data by minimizing the sum of squared error (SSR) to 1.36103.
