ENV-03-123 The Future of Petroleum Hydrocarbon Remediation: Site Closure Through Enhancement of In Situ Biological Degradation

Description:

Monitored Natural Attenuation (MNA) is the most important advancement in the field of remediation during the 1990’s. We have all come to understand it as the process that is responsible for removing the majority of the organic compounds at our contaminated sites. This is especially true for petroleum hydrocarbon sites. The problem has been that while this technology has been perceived as very cost effective, a majority of these projects have not reached closure within a reasonable and cost effective time frame. The reoccurring costs of a MNA program include the anticipated monitoring, reporting and agency interaction costs, and also the transactional costs associated with management (internal and consulting) of the project by the property owner while these projects remain open. There is mounting evidence that there is a more cost effective method to achieve site closure at many petroleum hydrocarbon sites. Several methods have been developed that can stimulate the rate at which the natural bacteria degrade the petroleum hydrocarbons. While these methods can cost significant amounts of money, the project reaches closure at a much faster rate than MNA. When the total costs of the project with and without stimulation are compared, the most cost effective process is often enhanced biodegradation. The main methods of stimulation involve providing alternate electron acceptors to the natural bacteria. Bacteria are more energy efficient when using oxygen or nitrate as their final electron acceptor than when using sulfate or other anaerobic pathways. This energy efficiency can translate into faster biological reactions and faster closures. Several case histories will be provided that show the results of adding oxygen and nitrate to enhance the natural bacterial actions at petroleum-contaminated sites. Cost analysis from these applications show that the up front expenditures for the enhancement processes can be recouped in 1 to 3 years compared to a MNA strategy.