Agriculture Reference
In-Depth Information
Many techniques of remediation of contaminated soil have been developed, such as
physical, chemical degradation, photodegradation. However, most of these methods have
some drawbacks in completely remediating hydrocarbon contaminated soil. Some of these
methods leave behind daughter compounds which are more toxic to the environment than
the parent compounds. Biological treatment offers the best environmental friendly method
for remediating hydrocarbon and heavy metal contaminated soil because it utilized the
capability of the indigenous microorganisms in the soil environment to break down the
hydrocarbons and heavy metals into innocuous substances.
Biological remediation, a process defined as the use of microorganisms or plants to detoxify
or remove organic and inorganic xenobiotic compounds from the environment is a
remediation option that offers green technology solution to the problem of environmental
degradation. This process relied upon microbial enzymatic activities to transform or
degrade the contaminants from the environment (Philp et al., 2005). It offers a cost effective
remediation technique, compared to other remediation methods, because it is a natural
process and does not usually produce toxic by-products. It also provides a permanent
solution as a result of complete mineralization of the contaminants in the environment
(Perelo, 2010). Advantages of biological remediation compared to other treatment
methods
include (Okoh and Trejo-Hernandez, 2006):
i.
Destruction rather than transfer of the contaminants to another medium.
ii.
Minimal exposure of workers to the contaminants.
iii.
Longtime protection of public health.
iv.
Possible reduction in the duration of the remediation process.
2. Impact of hydrocarbon and heavy metals contamination on environment
and human health
Hydrocarbon spills in the form of petroleum products both on land and in water, have been
a problem since discovery of oil as a fuel source. They can have devastating effects on the
biota of an environment. Oil spills and oil waste discharged into the sea from refineries,
factories or shipping contain poisonous compounds that constitutes potential danger to
plants and animals. The poisons can pass through the food web of an area and may
eventually be eaten by humans (Gibson and Parales, 2000).
Environmental contamination by hydrocarbons and petroleum products constitute nuisance
to the environment due to their persistent nature and tendency to spread into ground and
surface waters. Environmental pollution with petroleum and petrochemical products has
attracted much attention in recent decades. The presence of various kinds of automobiles
and machinery vehicles has caused an increase in the use of motor oil. Oil spillages into the
environment have become one of the major problems. Used motor oils such as diesel or jet
fuel contaminate natural environment with hydrocarbon (Husaini, et. al 2008). The
hydrocarbons spread horizontally on the groundwater surface thereby causing extensive
ground waters contamination (Plohl et al. 2002). Hydrocarbon contamination of the air, soil,
freshwater (surface water and groundwater) especially by PAHs has drawn public concerns
because many PAHs are toxic, mutagenic, and carcinogenic (Bumpus 1989; Clemente et al.
2001; Cerniglia and Sutherland 2001). Aromatic hydrocarbons are considered to be the most
acute toxic component of petroleum products, and are also associated with chronic and
carcinogenic effects (Anderson, et al., 1974). Aromatics are often distinguished by the
number of rings they possess, which may range from one to five (Anderson, et al., 1974).
