Contaminated Land and Bio-Remediation - Environmental Biotechnology: Theory and Application - page 111

Figure5.9 Schematicsoilslurrybioreactorsystem
bioreactors, may often be a more appropriate and effective response. Dependent
on the specific type of contaminants, this may necessitate a sequence of both
aerobic and anaerobic procedures, or even one which combines biological and
chemical steps to achieve the optimum remediation system. Under such circum-
stances, clearly each bioreactor features conditions designed to optimise specific
biological processes and degrade particular contaminants.
It should be clear from the preceding discussions that the actual process of
bioremediation employed will depend on a number of factors, amongst others
relating to the site itself, the local area, economic instruments, reasons for reme-
diation and the benefits and limitations of the actual technologies. Hence, it
should not be difficult to see that for any given contamination event, there may
be more than one possible individual approach and, indeed, as described earlier,
the potential will often exist for using integrated combinations of technologies to
maximise the effectiveness of the overall response. In this way, though depen-
dent on many external variables, a mix and match assemblage of techniques may
represent the individual BPEO. The merging of an ex situ treatment, like, for
example soil washing via a slurry reactor, to offer an intensive and immediate
lessening of pollution effect, with a slower in situ process to polish the site to a
final level, has much to recommend it, both environmentally and commercially.
Accordingly, it seems reasonable to conclude that the prevalence and relative
importance of such approaches will continue to grow over the coming years.
Remediation technology selection
As was stated earlier, there are several remediation techniques available, of
which bioremediation is just one and, for the most part, regional variables define