Bioremediation of a crude oil contaminated soil using water hyacinth (Eichhornia crassipes)

Crude oil contamination is a growing environmental concern in most oil processing regions of the world. This study assessed the efficacy of powdered Eichhornia crassipes (water hyacinth) as potential bio stimulant in the remediation of crude oil contaminated soil using three test treatments (20ml, 60ml and 100ml) and a control. The remediation process was monitored by assaying the total hydrocarbon content (THC) and soil pH of the soil on 16 cells for 90 days. However, there was a significant reduction (p < 0.05) in soil pH and THC with the introduction of powdered E. crassipes at different concentrations. Contaminated soil amended with 40g of Eichhornia crassipes had the highest THC loss of (41%), following this was contaminated soil amended with 60g of Eichhornia crassipes (31%) on the final day of remediation. The total culturable hydrocarbon utilizing bacteria in Eichhornia crassipes treated polluted soil increased from 1.4×106 Cfu/g to 8.2×105 Cfu/g while the total culturable hydrocarbon utilizing fungal counts in the Eichhornia crassipes treatment increased from 1.2 ×104  to 4.5 ×104 Cfu/g from the zero hour to the 90th day of the study. The time effect of the remediation process had P-value less than 0.05 for 20, 60 and 100ml crude oil contamination signifying that the time factor played important role in the remediation process. The use of organic nutrient sources such as Eichhornia crassipes nutrient powder is of good use as source of limiting nutrient needed for bioremediation of crude oil impacted medium.