Contaminated Land and Bioremediation 111Closing Remarks
While there is considerable overlap in technology costs, the economic element is
very largely identifiable in the general trends of use and, of course, biotechnology
is not applicable to all forms of pollution. The situation for bioremediation at
least seems set to benefit further as (in the UK) landfill tax, the escalating costs of
special waste disposal, and the extra demands of the EU Landfill Directive, which
is discussed in some detail in Chapter 8, have all combined to make biological
treatment an increasingly cost-effective option. The UK is by no means unique
in this respect. Similar changes have helped to make clean-up biotechnologies
more competitive elsewhere in the world also and it seems this trend is likely to
continue into the foreseeable future.
References
BioWise, UK Department of Trade and Industry (2001)Contaminated Land
Remediation: A Review of Biological Technology, Crown copyright.
Case Study 5.1 Oil Bioremediation (Texas, USA)
Sites contaminated by petroleum hydrocarbons are often particularly well suited to
bioremediation and there are many examples across the globe of the successful use
of biotechnology in such clean-up operations.
One particularly successful example, closely monitored by the Texas Parks and
Wildlife Department and the Texas Railroad Commission, involved the treatment of
petroleum-contaminated soil at a site within Tyler State Park, Texas, located close to
a large recreational lake. Historic oil exploration, pumping and gathering operations
had resulted in significant petroleum hydrocarbon contamination and the crude oil
storage tanks, which had been removed before the project began, had left behind
actual puddles of oil, in some places, though the contamination was generally of
shallow character, only extending to around 0.3–0.5metres in depth.
ETTL engineers, who had been engaged to do the clean-up, employed a process
using indigenous soil microbes harvested from the site, which were then artificially
multiplied in the laboratory before being reintroduced in a solution that also
contained nutrients and biosurfactants.
Thein situtreatment process used was a land-farming method, with the soil
being deeply ploughed before being sprayed with the microbial solution. The soil
was further tilled at fortnightly intervals to aerate it and keep its structure open,
and the hydrocarbon concentration, pH, soil temperature, and moisture levels were
monitored throughout. This allowed additional water, nutrients and pH buffers to
be added as required, to maximise the efficiency of the bioremediation system. The
final outcome exceeded the minimum legal requirements by a large margin and at
a cost significantly lower than traditional methods and slightly under that originally
anticipated.