Exploring the Potentials of Nipa Palm (Nypa fruticans) Ash and Rabbit Droppings for Enhanced Ex situ Bioremediation of Crude Oil Contaminated Soil

Abstract

Crude oil exploration, production and refinement in the Niger Delta region of Nigeria have resulted in the contamination of soil. The study was aimed at exploring the potential of Nypa fruticans ash (NFA), and rabbit droppings (RD) as biostimulants for enhanced ex-situ bioremediation of crude oil contaminated soil (COCS) in Yorla. A microcosm was set up in three sets of containers, each having a surface area of 328 cm2 and a volume of 1651 cm3. Exactly 300 g COCS was weighed into each container (Sets A-C). SetA contained 150 g RD; SetB had 150 g NFA while SetC was not amended to serve as a control (CT). Monitoring was done for 5weeks (0, 1, 2, 3 and 4) with all parameters measured at an interval of 1week. SetA had hydrocarbon utilizing bacterial (HUB) and hydrocarbon utilizing fungal (HUF) counts reduced from 1.76x104 to 0.55x103 CFU/g and 1.43x103 to 0.32x102 CFU/g respectively after four weeks, while SetB had HUB reduced from 1.76x105 to 1.42x104 CFU/g and HUF reduced from 1.43x103 to 0.51x103 CFU/g by week 4. In SetA, total petroleum hydrocarbon (TPH) reduced by 57.9% while in SetB, it reduced by 39.6% and SetC by 0.59%. TPH reduced significantly (p<0.05) by week 5 in the order: RD>NFA>CT. Bacteria isolated included Pseudomonas fluorescens, Micrococcus roseus, Escherichia coli and Bacillussubtilis while the fungi counterpart were Aspergillus sp., Candida lipolytica, Penicillium sp.and Rhizopus sp. Reductions in physicochemical parameters could be due to their utilization by oil degraders. Next line of action will be to apply this technology in situ for enhanced remediation of COCS.