Bioremediation of Petroleum Hydrocarbon-Polluted Mangrove Swamps Using Nutrient Formula Produced From Water Hyacint (Eicchornia crassipes)

Abstract

Laboratory-scale studies were carried out using a nutrient formula produced from Eicchornia crassipes plant to achieve bioremediation of crude oil impacted mangrove soil. In a 70 day study, the culturable heterotrophic bacterial population of the Eichhornia crassipes recipe increased from 6.26×10⁵ Cfu/g to 2.69×10⁷ Cfu/g. The control set-up had its total culturable bacterial count increased from 5.76×10⁵ Cfu/g to 1.24×10⁶ Cfu/g. Statistical analyses showed significant difference for the two conditions (p ≥ 0.05). The total culturable heterotrophic fungal count in the Eichhornia crassipes recipe treatment increased from 5.36×10⁵ Cfu/g to 2.50×10⁷ Cfu/g respectively. The total culturable hydrocarbon utilising bacteria in Eichhornia crassipes treated polluted mangrove soil increased from 2.52×10⁴ Cfu/g to 3.81×10⁷ Cfu/g. Statistical analyses showed significant difference at p ≥ 0.05 level for the two conditions (Eicchornia crassipes nutrient treated soil and control). The total culturable hydrocarbon utilising fungal counts increased significantly for both the control and Eichhornia crassipes treatment. There was no regular trend in pH changes in all the conditions. The conductivity value of the Eichhornia crassipes recipe treated soil decreased progressively. Phosphate, nitrate, %total organic carbon, Total Hydrocarbon Content (THC). Studies using Gas chromatographic analyses showed that in the Eichhornia crassipes recipe treated polluted mangrove soil, 0, 58.92 and 75.36% were lost at zero hour, 28th day and 70th day respectively. In addition, in the control experimental set-up, 0, 7.14 and 13.42% of TPH were lost at zero hour, 28th day and 70th day respectively. There was no significant difference between the control experiment and Eichhornia crassipes (p = 0.054). The use of organic nutrient sources such Eichhornia crassipes recipe/nutrient powder is of good use as source of limiting nutrient needed for bioremediation of crude oil impacted medium.