Advantages and Limitations of Phytoremediation

The use of plants for the removal of heavy metals from soil and water offers a wide range of advantages. Phytoremediation is a technology which can be applied in situ without moving or excavating large amounts of contaminated soil and leaves the topsoil in an undisturbed and usable condition [239]. It uses solar energy and is in general easy to apply. A variety of metals and radionuclides can be treated. As for the contaminated sites, phytoremediation provides a useful tool for sites, which cannot be readily remediated by other methods, e.g., sites of large extension with only low contaminant concentrations at shallow depths. Several plant species used for phytoremediation belong to well-studied crop plants so there is a wide knowledge available for application and management of those plants [240].

Another advantage of phytoremediation is the reduction or elimination of secondary air or water borne wastes as the plants provide ground cover, which stabilizes the soil and reduces wind or water erosion [241], Wind blown dust and erosion result in exposure pathways of direct inhalation of contaminated air and ingestion of food contaminated by deposition of suspended matter onto food plants [242], If hyperaccumulators are used, their biomass can be disposed of by incineration thus reducing the mass and volume of waste, which has to be deposited at landfills. Ratios as high as 200:1 have been reported for the comparison of conventional remediation methods (soil excavation and landfill disposal) with plant ash from incineration [243].

Phytoremediation is also very cost-effective compared to other remediation methods. The remediation of a contaminated site may include such processes as excavation, removal, isolation, or incineration of the contaminated soil, the transport and return of the residue to the site. Prices for this kind of remediation are reported to range from 200 € up to 600 € depending on site characteristics, transport, and landfill costs. In comparison, costs for the phytoremediation including site preparation, planting, and harvesting are as low as 5000 € for a one acre site [244], In general, cost estimate for soil remediation is about 25 € to 100 € per ton and 0.2 € to 1.5 € per m3 water [159] compared to approximately 20 € per m3 water when standard microfiltration is used [240]. Moreover, phytoremediation makes contaminated sites more aesthetically appealing and helps turning brownfields into greenfields [245],

Finally, public acceptance for phytoremediation is very high. The relationships that humans have to plants are rooted deep in our evolutionary past and Homo sapiens has a deeply held innate appreciation for their value as we all depend on plants giving food, medicine, and shelter [246]. Table 13 lists some general advantages and disadvantages of phytoremediation. Although phytoremediation has many advantages when compared to conventional remediation technologies it is also necessary to mention some limitations. Hyperaccumulators often accumulate only one specific element, which excludes their use to sites with multiple contaminations. The amount of hyperaccumulators available is limited and for some heavy metals, plants have yet to be found. Often these plants show slow growth rates and small production of biomass. A lot of research has still to be conducted as for the use of genetic engineering to introduce genes into fast growing plants, to regulate root growth, or to increase production of selected plant enzymes. Another serious limitation of phytoremediation is the long time required for the clean up of a site, which will take several growing seasons. In some cases, 18-60 months may be needed for site closure [159]. It has been estimated that natural hyperaccumulators might take 13-16 years to clean up a typical site [247], Therefore, it cannot be used when there is an imminent danger to human health and the environment. Investors and property developer may not wish to wait years until a site is cleaned up by phytoremediation. The use of plants does not result in a 100% removal of contaminants.

Table 13

General advantages and disadvantages of phytoremediation of heavy metals

Advantages_Disadvantages

Table 13

General advantages and disadvantages of phytoremediation of heavy metals

Advantages_Disadvantages

Cost:

Time:

Low capital and operating costs

Slower than some alternatives

Metal recycling provides further economic ad

Seasonally dependent

vantages

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  • preston
    What are the advantage of phytoremediation?
    6 days ago

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