a complete quantitative analysis, it illustrates differences that should be considered in selecting a remediation method for sustainability and to save money.
The five generally recognized sustainability criteria are:
- Harness or mimic a natural process,
- Minimize or eliminate energy or natural resource consumption,
- Reduce or eliminate releases to the environment, especially air,
- Permanently destroy contaminants, and
- Reuse or recycle inactive land or discarded materials.
Harness or Mimic a Natural Process
Bioaugmentation takes advantage of the natural ability of certain microbes to degrade contaminants. The driving force behind the microbial metabolism of organic chemicals is the organism’s ability to convert the contamination into useful energy and cell mass. The byproducts of aerobic metabolism are carbon dioxide and water.
While biostimulation can take advantage of the existing fauna, it usually takes time to establish the selective pressure necessary to build a high population of the beneficial organisms. Bioaugmentation can add a high population of the same or similar organisms that were isolated from the same or similar sites. The addition of a high population accelerates the cleanup as the opportunity for cell to contaminant contact is increased proportionately with the population.
The bioremediation method is sustainable if it is compatible with the natural geochemistry of the site. For example under aerobic conditions aerobic organisms capable of degrading the contaminants should be selected instead of putting energy and resources into changing the ground water chemistry to favor anaerobic organisms.
Minimize or Eliminate Energy or Natural Resource Consumption
Bioremediation has a very low carbon footprint because it does not require energy for the operation and does not require frequent field checks for operation and maintenance. The comparison with excavation or extraction techniques is obvious, but the comparison between bioremediation and chemical treatment is not. However, if one compares the water usage and waste products from chemical manufacturing and bioreactors for fermentation, bioremediation is more sustainable. CL-Out® is a certified partner in the US EPA’s Design for the Environment program, which provides independent assurance that CL-Out is produced in an environmentally friendly manner.
Reduce or Eliminate Releases to the Environment
There are two potential sources of releases to the environment during remediation. First, some extraction technologies transfer the contaminants from soil or water to an air stream that is treated or released untreated. Dusts generated by the excavation of contaminated soil also may contain the contaminants. Secondly, air emissions are generated by equipment used
during the application or maintenance of a treatment system.
Bioremediation destroys contamination in place and does not transfer contaminants to another media. In a typical application of bioremediation, the injection requires a drill rig for a few days. No equipment is necessary during the active remediation. Follow up monitoring visits are typically part of the routine monitoring required under any active treatment or natural attenuation monitoring.
Reuse or Recycle Inactive Land or Discarded Materials
Bioremediation has been used during the redevelopment of many brownfield properties, bringing the land back into productive use. One of the advantages of bioremediation is that property may be used or developed during remediation without opening pathways of contaminant exposure to workers or the environment.
Permanently Destroy Contaminants
One of the most important factors in selecting a remediation option is that it is complete. The partial degradation of contaminants such as incomplete dehalogenation of PCE can produce more harmful daughter products. Bioremediation can completely mineralize contaminants converting the chemicals to carbon dioxide and water. Furthermore, there are no residuals of the reaction that may alter the geochemistry of an aquifer.