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Abstract
The effect of microbial count of Pseudomonas aeruginosa bacteria amended with 20 g of nitrogen-phosphorous-potassium (NPK) fertilizer (15:15:15) on the biodegradation of crude oil-contaminated water was studied. Four samples, S 1, S 2, S 3, and S 4, with equal crude oil pollution load were inoculated with, 1 × 105 cfu, 2 × 105 cfu, 4 × 105 cfu and 8 × 105 cfu of P. aeruginosa respectively, and 20 g of NPK (15:15:15) fertilizer. The control sample, Sc, had only 8 × 105 cfu P. aeruginosa and no fertilizer.
Parameters such as oil and grease content, pH, BOD, COD, and turbidity were monitored over a nine-week period. At the end of the biodegradation period, a high percentage of oil and grease content was removed. The value reduced from 185.0 to 41.50 mg/L, 24.6 mg/L, 20.5 mg/L, 13.2 mg/L, 10.9 mg/L for S c , S 1, S 2, S 3, and S 4 respectively. There was also a drop in BOD, COD, turbidity, and pH of the samples under consideration. The S 4 sample had the highest reduction in both BOD and COD values. The initial value dropped from 82.0 to 27.5 mg/L and 158.4 to 64.8 mg/L for the BOD and COD, respectively. These values obtained fall within the Federal Environmental Protection Agency (FEPA) limits. The oil and grease content for S 4 sample was also reduced from 185 mg/L to 9.95 mg/L, while the pH value for this same sample, S 4, was 6.60 after the nine-week period of investigation.