Contaminated Land and Bio-Remediation - Environmental Biotechnology: Theory and Application - page 113

CaseStudy5.1 Ex-IndustrialSiteBioremediation(Utah,USA)

Remediation often plays a significant part in progressing redevelopment projects
centred on ex-industrial brownfield sites, with bioremediation enjoying an enviable
track-record of successes around the world, especially when the land in question
has suffered contamination from petroleum hydrocarbon products.
Never-the-less, applying biotechnological solutions to some of the challenges of
hydrocarbon clean-up has not always been uniformly successful across the entire
range of potential petroleum contaminants. Depending on the approach used, heavy
hydrocarbons in the C15-C40 range, which includes the likes of lubricating oils,
drilling mud and crude oil, have at times proven slower or more recalcitrant to treat.
Engaged to remediate a former steel mill facility, Utah-based Terra Nova Biosys-
tems faced C11-C21 diesel range organics (DROs) levels in excess of 100 000mg/kg,
along with broadly similar concentrations of naphthalene and PAH. The site also
contained dibenzofurans at 10 000mg/kg, along with lesser levels of benzene,
toluene, ethyl benzene and xylenes.
Treatment involved the use of hydrocarbonoclastic bacteria (HCB) which have the
innate ability to degrade hydrocarbon contaminants through their own metabolic
action and biosurfactant production. The proprietary process employed required
the indigenous HCB population to be artificially augmented and additional oxygen
and nutrients supplied to accelerate the insitubioremediation, resulting in effective
amelioration within three weeks.
The results far exceeded the US Environmental Protection Agency (EPA)/
Department of Environmental Quality (DEQ) standards for residential soils, with a
final total petroleum hydrocarbon gasoline range organic (TPH GRO) concentration
of < 5and ∼ 1mg/kg for all other contaminants.