TITLE:
Laboratory Design Criteria for Monitoring Biostimulated Bioremediation of a Crude Oil Contaminated Soil in Niger Delta Using Total Petroleum Hydrocarbon
AUTHORS:
Justin Nnaemeka Okorondu
KEYWORDS:
Bioremediation, Soil, Nutrient, Moisture Content, Total Petroleum Hydrocarbon, Crude Oil
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.11 No.1,
January
31,
2023
ABSTRACT: The remediation of crude oil-impacted soil has always been a challenge in
different soil environments and climatic conditions. Bioremediation technology
has offered a breakthrough in restoring crude oil-impacted soil/sediment in
muddy, dry soil and wetlands. Though, there have been varied environmental
conditions that have hampered the success of the bioremediation process. This
study has evaluated the effectiveness of a biostimulated bioremediation of
crude oil-impacted soil using some design criteria—nutrient amendment (NPK
fertilizer) and moisture content. Soil sample sets—A, B, C, D, E, F, and G were
impacted with crude oil at a ratio of 10 g/kg and amended with varying amounts
of nutrient 30, 60, and 80 g of N.P.K fertilizer. The medium for the
inoculation of the nutrient was water and the volume of water applied varied
from 30% to 80% saturation. The soil sample sets were harvested at an interval
of 3 months for 180 days to determine the concentration of total petroleum
hydrocarbon left in the soil. The analysis of the total petroleum hydrocarbon
was achieved using a GC-FID with a capillary column and autosampler. Soil
samples were extracted with mixed solvent dichloromethane and acetone at a 1:1
ratio. The total petroleum hydrocarbon results show that biostimulated
bioremediation achieved better results in soil sample sets with low moisture
content (30% water saturation) and moderate nutrient amendment. The
biodegradation of the sample sets with high water saturation and a high
nutrient amendment was slow with a higher amount of total hydrocarbon content
at the end of the 180 days. The variability in the hydrocarbon degradation
pattern of contaminated soil shows that biostimulated bioremediation achieved
better results in soils with low moisture content than in soil environments
with high water content (saturation). More so, nutrient overdosing of the
substrate hampered the effectiveness of the remediation process.