Environmental risks of bioremediation
In terms of deleterious effects of bioremediation on the environment, there are several potential problems which may arise:
- • Firstly, there is the scenario that the bioremediation fails and the contaminant remains in the environment. This may be a result of the low bioavailability of the compound or perhaps pollutant toxicity.
- • Secondly, there is the possibility that the bioremediation has resulted in only a partial breakdown of the pollutant. If the intermediate product is more toxic than the original compound, then this will lead to greater environmental damage. This has been observed during the degradation of polychlorinated ethene in groundwater where a more toxic intermediate, vinyl chloride, has been the main product of bioremediation rather than ethene.
- • Thirdly, if biostimulation has been employed, then there is the possibility that the treatment itself (e.g. addition of nutrients such as nitrogen and phosphorus) may cause deleterious effects on the environment through increased nutrient availability, which in soils would mean the release of nutrients into surface water resulting in increased eutrophication leading to algal blooms.
- • Finally, if bioaugmentation is employed, the addition of an organisms not native to that environment is added, there is an inherent risk that these organisms may significantly affect the functionality of the natural microbial community, causing deleterious effects on the environment.
In general, bioremediation utilises the natural ability of mixed populations of micro-organisms. The dynamics of such populations are complex and the potential for use of a released organism to enhance the bioremediation process therefore depends both on the environment and the nature of the pollutant (Aleer et al., 2011). However, with the release of any organism in the environment, the risk of utilising such a strategy must be fully considered. In some countries (e.g. Australia) the likelihood of being able to obtain permission from a body such as the Environmental Protection Agency to release a micro-organism is very small. However, in other countries (e.g. the United States), it is more likely to be permitted if a case is made. Nonetheless, this obstacle remains a significant challenge to the commercial use of micro-organisms in many countries.