BIOREMEDIATION OF USED ENGINE OIL CONTAMINATED SOIL BY VERMICOMPOSTING
BIOREMEDIATION OF USED ENGINE OIL CONTAMINATED SOIL BY VERMICOMPOSTING
No Thumbnail Available
Date
2012-08
Authors
AMEH, Alewo Opuada
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
This work was aimed at investigating the effect of earthworm (Eudrilus eugeniae) and organic
amendments on the bioremediation of used engine oil contaminated soil, a process thought to be
limited by mass transfer. The use of organic amendment alone facilitated bioremediation. The
results obtained showed that the first order bioremediation kinetics was a good description of the
process. The effect of surface area and frequency of mixing were also investigated and surface
area was found to be an important factor in bioremediation: having a significant effect on k (Pvalue
= 0.00045), the first order bioremediation constant. Thus increasing surface area improved
mass transfer. The effect of mixing on k was found to be insignificant (P-value > 0.436). For the
earthworm inoculated system at a used engine oil concentration of 100g used engine oil per kg of
soil, the worms recorded survivals of 100, 91.67 and 66.67% in soil contaminated with used
engine oil from motorcycle, truck/lorry and motorcar respectively. Investigations into the effect
of earthworm inoculation on soil properties indicated that earthworms had no effect on the
carbon and nitrogen contents but had significant effects on the moisture retention and aggregate
size distribution of the used engine oil contaminated soil (P-value of 0.025 and 0.029
respectively). In addition, the water holding capacity and mean weight diameter of the soil were
found to increase and decrease respectively with increasing earthworm concentration. The use of
earthworms was also found to have no significant effect on the microbial population as both
earthworms treated and untreated samples had comparable numbers of microbial count. The
effect of initial used engine oil concentration on rate of vermi-assisted bioremediation gave
mixed results. At high used engine oil concentrations, the presence of earthworms accelerated
the biodegradation process whereas at low initial used engine oil concentration the rate of
bioremediation was favored by the absence of worms. It was also discovered that the increase in
earthworm concentration favors higher rates of bioremediation. The Investigation into the uptake
/ elimination kinetics of some heavy metals from various concentrations of used engine oil in
(12.5 – 100 g/kg) showed that Zn, Cu, Ni and Cr were eliminated from the bodies of the worms
whereas Ti and Mn where accumulated. Furthermore, the metal uptake and elimination kinetics
showed good fit to a one-compartment model. Earthworm assisted bioremediation of petroleum
hydrocarbon contaminated soil from mechanic workshop indicated that the presence of the
worms accelerated the bioremediation process (petroleum hydrocarbon degradation). The rate of
bioremediation was found to be a function of the initial total petroleum hydrocarbon content as
well as the percentage earthworm survival. The kinetic model made up of the combined first
order reaction kinetics and first order catalysts deactivation kinetics was found to be a better fit
to bioremediation (with and without earthworm inoculation) than the first order bioremediation
kinetics alone in the bioremediation of simulated used engine oil contaminated soil as well as
contaminated soil from mechanic workshops.
Description
In Partial Fulfillment
Of the requirements for the degree
Doctor of Philosophy (Chemical Engineering)
Department of Chemical Engineering
Ahmadu Bello University, Zaria
Keywords
BIOREMEDIATION,, USED,, ENGINE OIL,, CONTAMINATED,, SOIL,, VERMICOMPOSTING