Phytotechnology – A green key to fighting soil pollution
Pollution is a problem which exists in every part of the developed and developing world which further causes harm to the ecosystem. Cleaning up of such contaminated sites is a must to nurture human health and environment.
Many initiatives have been put forward for controlling pollution in the past two decades. Eco-technology is now in lime-light as the risk associated with it is very less. Eco-technology consists of microbial technology (use of micro-organisms) and phytotechnology (use of plants). Phytotechnology entails a set of technologies in which plants are used to degrade, extract or immobilize the pollutant in order to remediate the environment. It can be applied for treating the contaminated land-fills, groundwater, surface water, and wastewater.
There are six types of mechanism associated with phytotechnology. These are listed below:
- Phytodegradation: Contaminants are enzymatically broken down within the plant tissues.
- Phytoextraction: The pollutants or contaminants are sequestered inside the plant.
- Phytohydraulics: Containment by controlling the transpiration rate of plants.
- Phytosequestration: Plants secret some phytochemicals which aid in sequestering the contaminants in the rhizosphere. Further, these are taken up by the plant and sequestered into the roots or the stems, thereby rendering these contaminants harmless.
- Phytovolatization: The contaminant is taken up by the plant and volatilized by transpiration stream.
- Rhizodegradation: Combination of microbial cultures and the phytochemicals released by the plant to facilitate degradation of the contaminant.
Unlike other remediation strategies, phytotechnology is site specific. Climate, vegetation and soil type are important parameters which promote better performance of phytotechnology. Evaluation of the site which needs to be cleaned up earlier will help to achieve better remediation. It can be used for remediating organic as well as inorganic pollutants. A few pollutants which can be remediated are volatile organic compounds (VOC), polycyclic aromatic hydrocarbons (PAH), petroleum hydrocarbons, heavy metals and radionucleides.
Advantages of using phytotechnology:
- The costs associated with the operations and maintenance are very low
- Plants can improve the air quality
- Vegetation can prevent soil erosion
- Site aesthetic value can be improved by plantation
Disadvantages of using phytotechnology:
- Time period required for remediation is comparatively longer than the traditional techniques
- Inappropriate for sites having significant depth
- Highly toxic pollutants may cause phytotoxicity, i.e. inhibit or prevent the plant growth
- Disposal of the plant material containing the pollutant
The first disadvantage can be solved by selecting a plant having a shorter life cycle. The second and third ones can be solved by applying plant growth promoting microbes which will help the plant withstand adverse conditions. The fourth problem can be solved by planning the downstream process. For example, heavy metals can be recovered by using this technology. Jatropha carcus is reportedly used for remediating contaminated sites, which can later be harvested and used for bio-diesel production. So, planning the process, using appropriate vegetation can help boost up the process. Phytotechnology is a field which needs to be researched and explored further. It can be a promising tool for cleaning up polluted sites.