Comparative Effectiveness of Activated Soil in Bioremediation of a Farmland Polluted Soil by Polyaromatic Hydrocarbon in the Niger Delta

摘要

Polyaromatic hydrocarbon contamination in terrestrial ecosystem is evidently one of the most crucial ecological threats in the Niger Delta as a result of their toxic, mutagenic and carcinogenic properties. Laboratory treatability study was carried out on soil from Ngia Ama in Tombia Kingdom impacted by artisanal oil refining operations, to evaluate the bioremediation effectiveness of activated soil from Bomu in Ogoni against other bioremediation techniques. Bioremediation study was monitored in 5 microcosms designated: biostimulation (BST) biostimulation- bioaugmentation (BSAG), bioaugmentation (AGN), bioattenuation (BAT) and sterilized control (STL) for 30 days. All treatments contained 1 kg (amendments inclusive) of Ngia Ama soil (PSN) sample. The biostimulation agent was inorganic fertilizer (NPK 20: 10: 10) while Bomu sample served as the bioaugmentation agent. Spread plate technique was employed to isolate and enumerate total heterotrophic, hydrocarbon utilizing and PAH-degrading bacteria (THB, HUB and PDB respectively). PAH-degrading bacteria were identified using molecular analysis while polymerase chain reaction (PCR) technique was employed to detect catabolic genes using specific gene primers. Gas chromatography-flame ionization detector (GC-FID) was employed to ascertain PAH concentration losses. The baseline PAH-degrading bacterial counts for Bomu and Ngia Ama samples were 4.6 x 10? CFU/g and 4.9 x 10* CFU/g respectively. The percentage losses of total PAH and TPH as analyzed by GC-FID were 68.7%, 70.0% (BST), 66.4%, 72.6% (BSAG), 68.4%, 64.7% (AGN), 63.0%, 67.0% (BAT) and 43.4%, 47.3% (STL), though there was no statistical differences between the various treatment setups at p < 0.05. Genera of Enterobacter, Shewanella, Burkholderia, Pseudomonas, Bacillus, Acinetobacter, Exiguobacterium and Stenotrophomonas were isolated from both samples. The PDB sequences have been deposited in GenBank under the accession numbers KX754444 to KX754459. The activated soil from Bomu showed effectiveness as biotsimulation thus can be used to remediate hydrocarbon polluted sites in the Niger Delta as a cheap in-situ option.