Apatent-pending collection of microbes that can be used both for addressing energy needs and cleaning up the environment has earned the US Department of Energy's (DOE) Savannah River National Laboratory (SRNL) kudos from a newsletter covering the rapidly expanding field of nanotechnology.
Nanotech Briefs awarded SRNL's BioTiger a spot on its fourth annual Nano 50 list, described as the top 50 technologies, innovators and products expected to revolutionise the industry.
BioTiger resulted from over eight years of extensive work that began at a century-old Polish waste lagoon. "DOE had originally funded us to work with our Polish counterparts to develop a microbe-based method for cleaning up oil-contaminated soils," said Robin Brigmon, SRNL fellow engineer. From that lagoon, they identified microbes that could break down the oil to carbon dioxide and other non-hazardous products. "The project was a great success," He adds. "The lagoon now has been cleaned up, and deer now can be seen grazing on it."
Recent efforts have shown that BioTiger naturally produces chemicals that may have other industrial uses as well. For example, it can be applied directly for cleaning up oil residues on surfaces such as concrete slabs and building foundations.
In addition to its original environmental cleanup uses, BioTiger has recently been shown to be highly effective for increasing oil recovery from oil sands without added chemicals.
Oil sands - also referred to as tar sands - are a combination of clay, sand, water, and bitumen, a heavy black viscous material. Currently, oil sands represent about 40 per cent of Canada's oil production. Approximately 20 per cent of US crude oil and refined products come from Canada, and a substantial portion of this amount comes from tar sands.
Oil sands are mined and processed to generate oil similar to that pumped from conventional oil wells, but extracting oil from these sands is more complex and requires more energy than standard oil recovery. Current methods require multiple steps including heating, mechanical mixing, and chemical additions to extract hydrocarbons from the oil sands.
There have been concerns about the environmental impact of these operations, including concerns about the amount of water used in the process, energy cost to operate the systems, runoff from the tailings ponds, wastewater from the facilities, and chemical residues in the water left over from the extraction process. Past efforts have generated large tailings ponds that still contain varying amounts of bitumen, indicating that the process did not efficiently extract all of the available oil.
An enhanced oil recovery process using BioTiger could provide a means to maximise capacity and minimise environmental impact, while remaining cost effective.
The BioTiger microbes attach themselves to the oil sands (see 'How it works', below), separating the oil from the sand particles. The microbes make the separation step easier, resulting in more removed oil and, potentially, reduced energy costs.
In a test using oil sands from Fort McMurray, Canada, BioTiger demonstrated a 50 per cent improvement in separation over four hours, and a five-fold increase at 25 hours.
It may also have potential for other oil recovery initiatives, including oil shale and other underground areas with oil deposits.
How it works
BioTiger is a novel, surfactant-producing microbial consortia that remediates polycyclic aromatic hydrocarbons (PAHs) and heavy metals. Having been isolated from a location with over a century of exposure to extreme environmental conditions, petroleum hydrocarbons, heavy metals, and associated solvents, it has properties and capabilities not demonstrated elsewhere. Potentially, the biosurfactant could be used as a cleaning or degreasing agent.
The bacteria strains produce biosurfactants under in situ and ex situ remediation conditions. The biosurfactant provides increased solubility of PAHs and access of the bacteria to the PAHs, thereby increasing the efficiency of the bioremediation.
PAHs are widespread pollutants particularly found in association with oil refineries, certain refined petroleum products, petroleum storage locations, and petroleum spill sites.
By use of microbes to accelerate remediation, treatment time for petroleum contaminated soil can be reduced to as little as 90 days. Cost savings can be achieved not only by the reduction in time of remediation but also by the ability to dispose of waste as not being mixed
Other locations with contamination of sediments and water by PAHs and metals include energy production facilities, wood treatment locations, harbours, brownfields, municipal and commercial waste disposal sites, and military installations including coastal harbour areas.
High levels of PAHs are associated with mutagenic and carcinogenic effects in humans and pose a high risk for migration to and pollution of soil and groundwater.
In situ bioremediation of wastes at landfills with or without the subsequent mining of the non-biodegradable material for disposal elsewhere would allow the re-use of significant portions of landfill space.
Low molecular weight, 2- to 3-ringed PAHs such as naphthalene, phenanthrene, and fluoranthene along with PAH degradation intermediates are removed by this technology. Also degraded and removed are 4-ring and higher molecular weight PAHs including pyrene and fluoranthene.
Typically, the 4-ring and higher PAHs are much more persistent in the environment and resistant to degradation compared to low molecular weight PAHs. The removal of 4-ring and higher PAHs by this technology is significant.
his biocatalyst also has surfactant properties produced by biosurfactant monomers useful in the removal of metals from contaminated soil and substrates. The biosurfactant monomers are produced in sufficient quantity that the monomers aggregate into three-dimensional structures including micelles. The biosurfactant micelles define polar head groups which bind with metal ions in the soil.
The micelles, containing the metal ions, can be removed by aqueous suspensions or flushing, thereby lowering the metal ion content of the substrate.
The resulting removed metals, contained within the biosurfactant micelles, are then more easily separated and concentrated for efficient disposal or storage. These metals could be recovered for recycling.
SRNL is managed for the DOE by the Washington Savannah River Company (WSRC). WSRC is responsible for transferring technologies to the private sector so that these technologies may have the collateral benefit of enhancing US economic competitiveness.
A US patent application has been filed on the biocatalyst and method and WSRC has invited interested companies with proven capabilities in this area of expertise to enter into a licensing agreement with WSRC to manufacture and market this device as a commercial product.
