Optimized approach for naphthalene wastewater biodegradation by Enterobacter ludwigii NS12 isolated from petroleum industry sludge: Bioreactor study and kinetic investigation

Abstract

Polycyclic aromatic hydrocarbons (PAHs) pollution is a pressing concern in environments, primarily due to human activities. Limited research exists on the degradation of PAHs by indigenous bacterial strains compared to other degraders. This study focuses on naphthalene biodegradation by isolated bacterial strains from petroleum waste. Naphthalene poses significant threats to ecosystems, inducing genotoxic, mutagenic, and carcinogenic effects. Bioremediation offers a safe and cost-effective solution by employing microbes to degrade naphthalene into non-toxic by-products. In this study, Enterobacter ludwigii NS12 found as the most efficient strain for naphthalene biodegradation. In the subsequent investigation the effect of key process parameters, including pH and temperature, on the biodegradation of naphthalene were studied. Under optimal conditions (pH 7.0 and temperature of 30 °C), Enterobacter ludwigii NS12 exhibited an 89.2 % removal efficiency in the bioreactor for naphthalene wastewater at a concentration of 300 mg/L. The confirmations of naphthalene biodegradation were investigated through residual analysis, revealing dibutyl phthalate and 1-octanol, 2-butyl as metabolites. Additionally, growth kinetic parameters μmax and Ks were evaluated, resulting in values of 0.2380 per day and 158.57 mg/L for Enterobacter ludwigii NS12, respectively. The findings of this study hold significant promise for the bioremediation of naphthalene contamination in the environment.