Environmental Engineering and Management Journal November 2011, Vol.10, No. 11, 1609-1616 http://omicron.ch.tuiasi.ro/EEMJ/ “Gheorghe Asachi” Technical University of Iasi, Romania BIOREMEDIATION OF PETROLEUM SLUDGE UNDER ANAEROBIC MICROENVIRONMENT: INFLUENCE OF BIOSTIMULATION AND BIOAUGMENTATION Srinivasula Reddy Venkata Mohan 1 , Mamilla Prathima Devi 1 , MotakatlaVenkateswar Reddy 1 , Kuppam Chandrasekhar 1 , Asha Juwarkar 2 , Ponnapalli Nageswara Sarma 1 1 Bioengineering and Environmental Centre, Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad 500 607, India 2 Environmental Biotechnology Division, National Environmental Engineering Research Institute (CSIR- NEERI), Nehru Marg, Nagpur, India Abstract Bioremediation is considered as one of the prominent and cost-effective cleanup technology to treat oily sludge disposals. In the present investigation anaerobic bioremediation of petroleum based oily sludge was studied in a slurry reactor by applying different experimental strategies viz., bioaugmentation, biostimulation and co-substrate addition. Total petroleum hydrocarbons (TPH) present in the oily sludge before and after degradation was extracted using soxhlet extraction procedure. The soluble fractions of TPH were eluted using column chromatography. Integrated process documented higher degradation efficiency. The combination of biostimulation, bioaugmentation and co-substrate addition showed efficient degradation of TPH (38.39%), aromatics (50.99%), aliphatics (44.48%), asphaltenes (29.62%) and NSO (nitrogen, sulphur and oxygen) compounds (15.23%). This condition was followed by biostimulation and bioaugmentation (36.89%) and individual operation of bioaugmentation (29.38%). Individual polycyclic aromatic hydrocarbons (PAHs) also showed good degradation pattern where, highest was observed with naphthalene (97.8%) followed by acenaphthylene (92.5%), fluorene (91.2%), anthracene (89.6%), phenanthrene (89.1%), fluoranthene (88.5%), pyrene (88.5%), benzo (A) anthracene (87.9%), chrysene (87.1%), benzo (A) pyrene (70.2%), dibenzo (A, H) anthracene (64.2%), benzo (G, H, I) perylene (49.5%). In all the reactors, degradation of lower ring compounds is significantly noticed compared to the higher ring compounds. Key words: anaerobic treatment, domestic sewage, oily sludge, polycyclic aromatic hydrocarbons, biostimulation, total petroleum hydrocarbons Received: January, 2011; Revised final: May, 2011; Accepted: June, 2011  Author to whom all correspondence should be addressed: e-mail: vmohan_s@yahoo.com; Phone/Fax: +914027191664 1. Introduction Oil is the principal source of energy for man and also an important environmental pollutant when enters into the environment (Gasparotti, 2010). In addition to the accidental contamination of ecosystems by oil spills, vast amounts of oily sludge generated in refineries from accumulated oily waste materials in the bottom of storage tanks and water-oil separation systems pose great challenges because of the expensive disposal methods (Oprea et al., 2009; Verma et al., 2006). Polycyclic aromatic hydrocarbons (PAHs) constitute an important fraction of petroleum hydrocarbons and they are considered as one of the major contaminants in soil and water environments because many of these compounds are found to be potentially toxic (Cristescu et al., 2009; Draghici et al., 2009; Tsai et al., 2001). PAH compounds represent a large and diverse group of organic molecules having a broad range of properties, differing in molecular weight, structural configuration, water solubility, number of aromatic