Abstract:
Refining of crude oil generates large volumes of wastewater containing phenolics, long-chain hydrocarbons, polynuclear aromatic hydrocarbons (PAHs), heterocyclics and heavy metals, and thus requires treatment before disposal. Most of the PAHs and heterocyclic PAHs are toxic, mutagenic and carcinogenic. Carbazole (CBZ), dibenzothiophene (DBT) and fluorene (FLU) are representative compounds of nitrogen and sulphur heterocyclics and PAHs containing three fused aromatic rings. CBZ, FLU, and DBT degradation in petroleum refinery wastewater (PRW) was evaluated through biostimulation and bioaugmentation approaches. For PRW bioaugmented with Pseudomonas aeruginosa RS1, altering the nutrient formulation from unoptimized to optimized media improved the degradation after 14 days from 47 +/- 5.2%-69 +/- 4.3 % for CBZ, 20 +/- 11%-35 +/- 14 % for FLU and 24 +/- 10%-32 +/- 13 % for DBT. Significant removal of all compounds was observed from a ternary mixture of CBZ, FLU, and DBT (10 mg/L each) in PRW supplemented with the optimized media. Acclimatization of P. aeruginosa RS1 to CBZ, FLU, DBT and their mixture impacted the removal of indigenous aromatics and heterocyclics from PRW. The results revealed importance of nutrient supplementation and culture acclimatization for enhancing degradation of recalcitrant organics from PRW.