Laboratory-Scale Degradation of Crude oil in a Simulated Low Energy Environment

Abstract

A 35- day study was carried out to simulate the effect of nutrient release on the rate of crude oil degradation/removal in low energy environments, using granular and capsular slow release fertilizers. Hydrocarbon degradation was simulated in a 500ml capacity Erlenmeyer flask containing 200ml mineral salt solution and 0.5 ml contaminant (crude oil) and seeded with suspensions of a 24-h old pure cultures of bacterial isolates identified as Pseudomonas sp., Bacillus sp. and Micrococcussp. Agar agar (type 1) was used in the production of the slow release fertilizer. During the35-day period of study, a strong positive correlation existed between bacterial biomass and the nutrient source (nitrate nitrogen) (r = 0.530), while a strong negative correlation was observed between bacterial biomass and total hydrocarbon content (r = -0.957) was observed, using the 2-tailed Pearson's correlation model. Also, statistical analysis using the one-way analysis of variance showed there was a significant difference in the mean values of the various treatment options, A – D, compared to the control E (p>0.05). NPK discovered to be a better source of nutrient than urea for the production of slow release fertilizers for use under this condition. Also, the granular slow release fertilizer (SRF) supported more bacterial growth rate and a concomitant hydrocarbon removal than the capsular SRF. Granular SRF is recommended for use under this condition for optimal results.  This is an important achievement in environmental biotechnology as the use of marine biopolymer is innovative and the granular SRF is as well a close substitute to direct fertilizer application, having the potentials of sustained supply of nutrient in a controlled fashion.