Effect of Microbial Count of P. aeruginosa on Biodegradation of Crude Oil Contaminated Water

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 x 10(5) cfu, 2 x 10(5) cfu, 4 x 10(5) cfu and 8 x 10(5) cfu of P. aeruginosa respectively, and 20 g of NPK (15: 15: 15) fertilizer. The control sample, Sc, had only 8 x 10(5) 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 S4 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.