Batch studies with Exiguobacterium aurantiacum degrading structurally diverse organic compounds and its potential for treatment of biomass gasification wastewater

Biomass gasification wastewater primarily consists of phenolics, nitrogen-heterocyclics and polynuclear aromatic hydrocarbons (PAHs). Biodegradation of these compounds present individually as sole substrate is studied in batch cultures in presence of Exiguobacterium aurantiacum. It demonstrated good potential for degrading phenol, pyridine, quinoline, benzene and naphthalene present at initial concentration (C-in) of 500 mg l(-1). E. aurantiacum could also utilize 3- and 4-ring PAHs, phenanthrene, fluoranthene and pyrene as sole substrate present at 100 mg l(-1) (C-in). While significant increase in absorbance was observed on 3 and 4-ring PAHs, the increase in number concentration of viable cells and extent of degradation was relatively low. E. aurantiacum could effectively degrade a synthetic biomass gasifier wastewater comprised of these compounds with a total COD of 1326 mg l(-1) and biokinetic studies revealed applicability of Monod's kinetics for culture growth on gasifier wastewater. The half velocity constant (K-s) and maximum specific growth rate (mu(max)) were 651 mg l(-1) and 1.86 d(-1), respectively. All components in the wastewater were degraded simultaneously and compounds with comparable concentration depicted comparable degradation rates. E. aurantiacum could degrade the organics in biomass gasification wastewater even when the ammoniacal-nitrogen concentration was increased up to 1000 mg l(-1). Bioaugmentation with E. aurantiacum can significantly enhance biological treatment of biomass gasification wastewater. (C) 2013 Elsevier Ltd. All rights reserved.