Ex-situ bioremediation of real-field crude petroleum sludge was evaluated to elucidate the role of co-culture (bioaugmentation) and external nutrients supplementation (biostimulation) under anaerobic microenvironment. Maximum removal of total petroleum hydrocarbons (TPH) was observed by integrating biostimulation with bioaugmentation (R5, 44.01%) followed by bioaugmentation alone (R4, 34.47%), co-substrate supplemented operations [R6, 23.36%; R3, 16.5%; R2, 9.88%] and control (R1, 4.36%). Aromatics fraction showed higher degradation in all the conditions studied. Fate of six selected polycyclic aromatic hydrocarbons (PAHs) was evaluated during bioremediation. Among these, four ring PAHs compounds showed good degradation by integration of biostimulation with bioaugmentation (R5) while bioaugmentation alone (R4) documented good degradation of three ring PAHs. Lower ring PAHs compounds showed good degradation with the application of biostimulation (R6). Fluorescent in situ hybridization (FISH) detected the presence of known PAHs degrading microorganisms viz., Bacillus, Pseudomonas, Acido bacteria, Sulphur reducing bacteria Firmicutes, etc. Application of biostimulation and bioaugmentation strategies alone or in combinations documented noticeable influence on the degradation of petroleum sludge.
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.
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