Petroleum oil sludge resulting from crude oil storage, illegal crude oil refining and bunkering activities constitutes environmental hazards and pollution in the crude oil producing communities in the Niger Delta region of Nigeria. Biostimulation with N.P.K. fertilizer option C, bioargumentation with indigenous hydrocarbon utilizing bacteria (HUB) option B, combination of biostimulation and bioaugmentation as option A and option D was without any bioremediation treatment were employed in the bioremediation of brackish water artificially polluted with petroleum oil sludge. Brackish water sample was obtained from Elechi Creek, Port Harcourt Rivers State. Petroleum oil sludge sample was obtained from Crude Oil Processing Plant in Obegi community, Rivers State. Bioremediation was monitored for 56 days using the percentage ratio of total petroleum hydrocarbon (TPH) losses for each period to TPH loss at day 0. The result of physicochemical analysis of the petroleum sludge showed that aliphatic hydrocarbon (n-alkanes) ranged from C13 – C35, with concentrations ranging from 26.12-7,713.62ppmwith TPH of 89,509.9ppm. The polycyclic aromatic hydrocarbon (PAH) range was 0.03-5.36ppm with total concentration of 24.21ppm. Heavy metal analysis showed; iron (49.42mg/kg), Zinc (3.79mg/kg), Nickel (4.53 mg/kg) and manganese (6.90 mg/kg). The average total heterotrophic bacterial (THB) and (HUB) counts for petroleum sludge were; 2.5 x 105cfu/g and 2.0 x105cfu/g and for the brackish water sample were 1.39 x 106cfu/ml and 1.1 x 104cfu/ml respectively. Statistical analysis (ANOVA) showed that the THB and HUB counts were significantly different at 5 percent levels (P<0.05) in the different treatment options during the bioremediation period. Changes in physico-chemical parameters showed that pH, alkalinity, conductivity, chemical oxygen demand, nitrate and phosphate were significantly different (P<0.05) while there were no significant differences (P>0.05) in the following parameter; salinity biochemical oxygen demand and total hydrocarbon continent.Using least significant difference (LSD), treatment option D and the control option E were different from treatments A, B and C. The phylogenetic analysis identification of the HUB isolates implicated in the degradation process revealed a closely related ness to the following organisms, Lysinibacillus sphaericus, Klebsiella pneumonia and Alcaligenes faecalis of different strains. The bacterial sequences submitted to Genbank were assigned Accession Number KX817218-KXV7225. The percentage losses in TPH from Gas Chromatography (GC) results showed the following; option A (91.8%), option B (92.5%), C (95%) D (57.8%) and option E control (39.5%) respectively. The results suggest that the application of biostimulation with N.P.K fertilizer, bioaugmentation with indigenous HUB or a combination of both will enhance the bioremediation of petroleum sludge polluted brackish water system in the Niger Delta of Nigeria.

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