Page 6 - OSMERT-2 Module 6 (inside pages) final
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effectively detect, assess, predict and monitor (in spatial and temporal terms) oil spills in this
               area. This will help reduce the resultant economic, ecological and even social risks that
               normally  follow spill incidents. To achieve all  these, an objective, reliable, computer based
               information management systems is therefore needed to support all the  strategic activities
               related to oil spill management.

               It is in support of the earlier call for the establishment of an Oil Spill Information Management
               System (OSIMS) for the country that this paper sees the integration of bioremediation types
               and strategies and the application of GIS as indispensable tools that will enhance knowledge
               and the process for remediating hydrocarbon polluted sites sustainably in the Niger Delta as
               addressed in this lecture.


               Bioremediation Strategies
               Depending on the degree of saturation and aeration of an area, Vidali (2001) identified different
               strategies of bioremediation  to include:In situ,  Ex situ  and Bioaugmentation.  For instance, he
               defined In situ techniques as those that are applied to soil and groundwater at the site with
               minimal disturbance. This strategy according to Sylvia (1995) and Sridevi, Lakshmi, Swamy&Rao
               (2011) is considered the most desirable options due to lower cost and less disturbance since
               they provide the treatment in place avoiding excavation and transport of contaminants. On the
               other hand, Ex situ techniques are those that are applied to soil and groundwater at the site
               which has been removed from the site via excavation (soil) or pumping (water). Bioaugmentation
               techniques involve the addition of microorganisms with the ability to degrade pollutants.

               Type of soil - Low clay or silt content treatment is limited by the depth of the soil that can be
               effectively treated. In many soils effective oxygen diffusion for desirable rates of bioremediation
               extend to a range of only a few centimeters to about 30 cm into the soil, although depths of 60
               cm and greater have been effectively treated in some cases.

               In situ Bioremediation
               The most important land treatments are:

               Bioventing is the most common in situ treatment and involves supplying air and nutrients through
               wells to contaminated soil to stimulate the indigenous bacteria. Bioventing employs low air flow
               rates and provides only the amount  of oxygen necessary for the biodegradation while
               minimizing volatilization and release of contaminants to the atmosphere. It works for simple
               hydrocarbons and can be used where the contamination is deep under the surface.

               In situ biodegradation involves supplying oxygen and nutrients by circulating aqueous solutions
               through contaminated soils to stimulate naturally occurring bacteria  to degrade organic
               contaminants.  It can be used  for soil and groundwater. Generally, this technique includes

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