Phytoremediation is an emerging technology that uses living plants to remove, degrade, or contain environmental contaminants such as heavy metals, pesticides, solvents, explosives, and crude oil. There are various phytoremediation types including phytoextraction, phytostabilization, rhizofiltration, and phytodegradation each utilising plants to clean the environment.
Phytoremediation plants are specially selected vegetation that absorbs, metabolizes, or transforms pollutants from soil, water, or air. In this article, we will cover phytoremediation meaning, phytoremediation types, examples, and phytoremediation notes in detail.
Phytoremediation is a plant-based technique for extracting and eliminating elemental contaminants from the environment or decreasing their bioavailability in soil. Plants may take ionic compounds from the soil via their root systems, even in low quantities. Plants extend their root systems into the soil matrix, generating a rhizosphere ecosystem that accumulates heavy metals and controls their bioavailability while also recovering damaged soil and controlling fertility.
Also Read: Bioremediation – Meaning, Examples & Types of Bioremediation
Various types of phytoremediation can be employed depending on the type and extent of contamination. The types of phytoremediation are mentioned below:
Phytoextraction
Phytoextraction, also known as photoabsorption and phytoaccumulation, occurs when plants absorb soil contaminants and water through their roots and accumulate biomass through translocation. It is a fascinating process where plants absorb and accumulate pollutants from soil or water into their roots, shoots, or leaves above ground. This method relies on the roots' ability to uptake elements from the surrounding environment and transport them into the aerial parts of the plant. Certain plants, known as hyperaccumulators, excel at this task, demonstrating a remarkable capacity for absorbing and storing pollutants.
Also Read: Environmental Pollution
Phytodegradation
Phytotransformation, also referred to as phytodegradation, represents a vital process in environmental remediation where organic pollutants from soil, sediments, or water are converted into more stable and less hazardous forms by plants. This transformation occurs as plant roots secrete enzymes that break down organic chemicals, which are then absorbed and expelled through transpiration.
Phytotransformation is particularly effective with herbicides, trichloroethylene, and methyl tert-butyl ether. This mechanism of environmental detoxification involves plant metabolism directly altering compounds, resulting in their inactivation, degradation (phytodegradation), or immobilization (phytostabilization).
Phytostabilization
Phytostabilization is a crucial method employed to mitigate the movement and dispersion of contaminants in soil. This process involves plants immobilizing leachable elements by adsorbing and bonding them into their structures, forming a stable mass from which toxins cannot easily re-enter the environment. By attaching contaminants to soil particles near their roots, plants effectively reduce the availability of these pollutants for uptake by other plants or humans. Unlike phytoextraction, which involves extracting contaminants into the plant tissues, phytostabilization focuses on sequestering pollutants within the soil matrix.
Phytostimulation
Phytostimulation involves the breakdown of pollutants through activity in the rhizosphere. This process is driven by the presence of proteins and enzymes produced by plants or soil organisms like bacteria, yeast, and fungi. These biological agents play a crucial role in breaking down pollutants. For instance, certain bacteria are capable of degrading hazardous contaminants such as fuels and solvents, transforming them into benign and harmless byproducts.
Rhizofiltration
Rhizofiltration is a technique for eliminating hazardous substances and excess nutrients from water by filtering it through a network of roots. Pollutants are absorbed by the roots or transmitted to them. This approach is commonly used to clean up contaminated groundwater by either planting directly in the contaminated region or removing the contaminated water and transporting it to the plants off-site. Plants are often cultivated in a greenhouse under controlled circumstances in either scenario. This approach is used to reduce pollution in wetlands and estuaries.
Phytovolatilization
Phytovolatilization is a process by which plants absorb contaminants from the soil or water and release them into the atmosphere in the form of volatile compounds. This mechanism involves the uptake of pollutants by plant roots, followed by their transport through the plant tissues and subsequent release into the air through transpiration or other plant processes.
Some plants which are useful in the phytoremediation process are given below:
- Sunflower (Helianthus annuus): Known for its ability to absorb heavy metals such as lead, arsenic, and cadmium from contaminated soil.
- Indian Mustard (Brassica juncea): Effective in accumulating heavy metals like nickel, zinc, and selenium, particularly in its shoots and leaves.
- Poplar Trees (Populus spp.): Commonly used for groundwater remediation, as their extensive root systems can absorb and metabolize contaminants like trichloroethylene (TCE) and benzene.
- Vetiver Grass (Chrysopogon zizanioides): Utilized for soil and water remediation, as its dense root system can absorb and accumulate pollutants, including heavy metals and organic compounds.
- Water Hyacinth (Eichhornia crassipes): Known for its ability to remove nutrients and organic pollutants from contaminated water bodies through absorption and bioaccumulation.
Phytoremediation has been successfully applied in various settings to address a wide range of environmental issues, including:
- Soil and water Remediation: Phytoremediation is commonly utilized in stable polluted soil and aquatic habitats.
- Mine Sites: Phytoremediation applications include the restoration of abandoned metal mine sites and areas affected by the deposition of polychlorinated biphenyls (PCBs) from industrial processes. Additionally, phytoremediation is used to manage ongoing pollution from active coal mines, helping to reduce the impact of pollutants on soil, water, and air quality.
- Pesticides, Crude Oil, and Its Derivatives: Phytoremediation has been successfully employed worldwide to reduce a range of pollutants such as metals, pesticides, solvents, explosives, and crude oil and its byproducts. This approach leverages plants to absorb, break down, or immobilize contaminants, contributing to environmental cleanup efforts.
- Waste Sites: Plant species like mustard, alpine pennycress, hemp, and pigweed have demonstrated their ability to accumulate high concentrations of toxins at toxic waste sites. This unique trait makes these plants valuable for remediation efforts, where they can help remove pollutants from the environment through their natural processes of absorption and detoxification.
Phytoremediation offers several advantages over conventional remediation methods, including:
- Ecologically Friendly Option: Because it may reduce pollutant exposure to the environment and ecosystem, it is an ecologically friendly method.
- Applicability and Easy Disposal: This technique is readily disposed of and may be used across a broad range.
- Reduces Erosion and Spreading: By stabilizing heavy metals, it lowers the chance that pollutants will spread and reduces erosion and metal leaching.
- Enhance Soil Fertility: By introducing different organic matter into the soil, it may also enhance soil fertility.
However, phytoremediation also has disadvantages, such as:
- Relocation not Removal: Phytoremediation is the relocation of dangerous heavy metals rather than their removal from the environment.
- Limited Scope: Only the surface area and depth occupied by the roots allow for phytoremediation.
- Slow Growth and Limited Biomass: The slow growth and limited biomass necessitate a long-term commitment.
- Pollutants Cannot Be Completely Avoided: Plant-based remediation approaches cannot completely eliminate pollutant leakage into groundwater.
- The impact on plant survival: The toxicity of polluted land, as well as the overall quality of the soil, affect plant viability.
- Metal Bonding to Organic Stuff: When a plant absorbs heavy metals, the metal may get bound to the organic matter in the soil, rendering it hard to remove.
Here are some examples of phytoremediation applications:
- Plants like Indian mustard can absorb and accumulate heavy metals such as lead and cadmium from contaminated soil.
- Trees like poplar are used to degrade organic pollutants such as solvents (e.g., trichloroethylene) through rhizodegradation.
- Aquatic plants such as water hyacinth and duckweed absorb excess nutrients like nitrogen and phosphorus from polluted water bodies, preventing eutrophication.
- Constructed wetlands with specific plants promote microbial activity to break down contaminants in wastewater.
- Grasses like switchgrass aid in microbial degradation of hydrocarbons in soil affected by oil spills.
- Willow trees are used in landfill caps to manage leachate and stabilize slopes, improving environmental conditions at landfill sites.
Phytoremediation offers a promising and sustainable solution to address environmental contamination issues. By leveraging the natural abilities of plants, this approach provides a cost-effective and eco-friendly alternative to traditional remediation methods. While there are challenges to overcome, ongoing research and advancements in this field continue to expand the potential applications and effectiveness of phytoremediation. As we strive for a cleaner and healthier environment, phytoremediation represents a valuable tool in our arsenal of remediation strategies.
Also Read:
Similar Reads
Process of Bioremediation Bioremediation is a type of biotechnical waste management process used to clean polluted water and soil. The process of bioremediation involves the use of microorganisms such as bacteria, fungi, etc. Various polluted areas such as polluted soil, water, municipal water tanks, sewage water, etc are cl
6 min read
Precipitation Titration Precipitation titration process is the backbone of analytical chemistry since it is a suitable method for determination of concentrations of dissolved substances in a solution. This technique requires precipitation by a controlled chemical reaction of the analyte with a reagent solution. Through acc
7 min read
Preparation of Soil Soil is a critical natural resource. Soil is the earth's thin surface layer composed of mineral particles formed by the breakdown (weathering) of rocks, decayed organic materials, living organisms, water, and air. Soil formation occurs through a variety of processes, including weathering of rocks an
6 min read
Water Purification Water is carried through canals or lengthy pipelines in a water purification system, which contains various pollutants and suspended particles from rivers and lakes. River water is commonly used to supply cities with drinking and dining water. This water is unsafe for drinking or dining because it c
6 min read
Polymerization Polymerization is the process of creating polymers. Several monomers combine by process of polymerization to form various polymers. These polymers are then processed to make various products. Polymers are of great importance in our daily life. In this article, we will learn about What is Polymerizat
11 min read