Over the last 20 years many biotechnologies have been proven as a viable means to mitigate the impact of the fossil fuel industry. Recent advances in research have lead to the development and field implementation of innovative treatment technologies such as bioventing, bioslurping, biofiltration, biobarriers, phytoremediation and the use of genetically engineered organisms. This paper provides a review of recent environmental biotechnology developments, using case studies to illustrate the benefits and limitations of each technology.
Biotechnology refers to "any technology based on or required by the activities of microorganisms" (1). Aerobic and anaerobic metabolic pathways biotransform and destruct various classes of hydrocarbons. There are many applications of biotechnology in the fossil fuel industry from enhanced oil recovery to environmental remediation.
Benefits of environmental biotechnologies that have contributed to their commercialization are:
low capital and operating cost,
minimal specialized equipment requirements, and
availability of trained contractors to implement the technologies.
Disadvantages of biotechnologies which have limited widespread implementation are:
limitations for treating multiple contaminants within a single waste,
slow reaction rates,
bioavailability limitations, and
conversion of some contaminants to more toxic metabolites.
This paper presents five innovative biotechnologies with examples of their use in the fossil fuel industry mitigating petroleum contamination. One strategy to overcome the limitations of biotechnologies is to genetically engineer organisms capable of degrading a wide variety of substances at increased degradation rates. This paper describes the genetic modification strategies with reference to improved degradation rates and the regulations in Canada affecting production of genetically engineered organisms and their use within Canada.
Bioventing is the process of supplying air to the vadose zone to stimulate aerobic biodegradation of a contaminant. The Texas Research Institute first reported bioventing in 1980 and 1984 during an experiment using a surfactant treatment to enhance recovery of spilled gasoline. The researchers recognized the occurrence of bioventing when trying to determine the fate of 120L of unaccounted for spilled gasoline (2.3). Many field scale experiments were conducted in the Netherlands during the 1980s (4).
In order for bioventing to be successful, the site must contain soil that is gas permeable and the contamination must be above the water table in the vadose zone. Contaminants that are readily biodegradable under aerobic conditions such as petroleum hydrocarbons are most suitable for treatment with bioventing (5).
Bioventing systems vary depending on unique site and contaminant conditions. The simplest layout is composed of an air injection well only. Other systems may include an air injection well into the contaminated soil and an extraction well in a clean soil area. Nutrients application and dewatering may be incorporated in areas where there is a nutrient deficiency and the moisture content is too high.
A successful bioventing design must consider three site characterizations before implementation (4): 1) A soil gas survey to determine the oxygen concentration of the soil. Contaminated soils already containing high levels of oxygen are not treatable using bioventing.