Bioremediation-Techniques and Methods
| Site: | Justwrite |
| Cours: | Nature's Solution to Pollution: An Introduction to Bioremediation |
| Livre: | Bioremediation-Techniques and Methods |
| Imprimé par: | Guest user |
| Date: | vendredi, 31 octobre 2025, 14:49 |
1. In-Situ Bioremediation
In-situ bioremediation is the process of using bioremediation to remove dangerous chemicals that are present in the soil or water in place meaning the contamination is addressed where it is located.
In -situ bioremediation can be either intrinsic (using naturally occurring microorganisms) or engineered (introducing nutrients or specific microorganisms). Examples include bioaugmentation, bioslurping, biosparging, natural attenuation, bioventing, and biostimulation.
2. Ex-Situ Bioremediation
Ex -Situ bioremediation involves removing the contaminated material (e.g., soil, sediment) and treating it at another location.
3. Phyto remediation
Removing heavy metals from the environment is very difficult because their degradation, like other pollutants, is not possible either biologically or chemically
An innovative technique that is non-invasive, economical, and visually beautiful is phytoremediation. “phytoremediation,” uses plants to clean up the environment as they can extract, accumulate, and depollute the substrate (soil, air, and water) from the contaminants through physical, chemical, or biological processes.
Metallothioneins, phytochelatins, metalloenzymes, metal-activated enzymes, and numerous metal storage, carrier, and channel proteins are among the many plant-based metal-binding proteins (MBPs) that play a major role in the phytoremediation of heavy metals.
To increase their ability for phytoremediation, plants undergo genetic modification. Bacillus megaterium's expression of the mercuric ion-binding protein enhances Arabidopsis's ability to accumulate metals.
Phytoextraction
Plants uptake pollutants from soil, water, or sediments by their roots and transfer them to the aboveground biomass where they accumulate, such as in shoots or other harvestable parts of the plant. This is known as phytoextraction
Phytostabilization
Phytostabilization means establishing a plant covering the surface of polluted sites to limit the movement of contaminants within the vadose zone by root accumulation or immobilization inside the rhizosphere, therefore lessening off-site pollution.
Phytovolatilization
Phytovolatilization refers to the use of plants to absorb heavy metal pollutants and transform them into volatile, less hazardous chemical species via transpiration. Some of the heavy metals, such as, Hg, and Se, may exist in the environment as gaseous species .
A small number of naturally occurring or genetically engineered plants, such as muskgrass (Chara canescens), Indian mustard (Brassica juncea), and Arabidopsis thaliana, have been shown to absorb heavy metals and transform them to gaseous forms within the plant before releasing them into the environment
Metal-binding proteins in plants
Phytochelatins (PCs)
Plant PCs are cysteine-rich low-molecular-weight polypeptides that are synthesized enzymatically, and their formation is stimulated by the presence of heavy metals .PCs chelate heavy metals by using their thiol groups. The complexes of metals and PCs that are produced as a consequence are stored in vacuoles.
Metallothionein
Plants have developed some adaptations to tackle metal ion concentrations’ increase in soil. An excessive amount of essential metal ions also causes toxicity similar to the non-essential metal ions; the foresaid mechanism provides metal tolerance as well as plays a significant role in the detoxification of excessive metal ions. MT was first discovered in animals than in plants; plant MTs have been discovered only approximately 30 years ago.
Transporter proteins
The transporter proteins of the plants can uptake, translocate and, sequester the heavy metals to provide tolerance to the plants and eventually remediate the contaminated soil.
4. Mycoremediation
Fungi are used in mycoremediation, a subclass of bioremediation, to break down, restore, and repair damaged environments . The long threads (hyphae) of the fungi used in mycoremediation adhere to roots, rocks, and soil particles to form a filamentous body that can withstand heavy metals and adjust its growth to temperature, pH, and nutrient variations. Because of their unique hyphal network, biomass, and long lifecycle, fungi are preferred over bacteria in the bioremediation of polluted settings.
Fungi's broad metabolic range allows for a wide range of applications in the removal of different pollutants. Polysaccharides and proteins containing amino, phosphate, hydroxyl, sulfate, and carboxyl groups that bind metal ions are found in fungal cell walls.
The ligand atoms required to create complexes with metal ions, which draw and hold metals in the biomass, are supplied by these functional groups. By choosing metal-tolerant fungus from a contaminated environment, the potential for metal removal is assessed. An efficient site-specific bioremediation method may involve the bioaugmentation of fungus that have the ability to absorb metals.
5. Bioaugmentation
The technique of adding particular microorganisms to contaminated areas to promote bioremediation and increase the breakdown capability of pollutants is known as bioaugmentation. Bioaugmentation is frequently employed in bioremediation to biodegrade environmental contaminants and resistant pollutants. It can be applied to wastewater and soil treatment.
Bioaugmentation can be done in situ (directly in the contaminated environment) or ex situ (outside of the natural environment, such as in a lab or treatment facility).
Bioaugmentation can be more efficient and targeted than relying solely on natural microbial populations, as it introduces organisms specifically designed to degrade certain pollutants.
There can be challenges with ensuring the introduced microbes survive and thrive in the contaminated environment, and there are also potential risks of introducing non-native species.
6. Bio stimulation
A bioremediation method called biostimulation increases the activity of already-existing microorganisms in a contaminated environment to break down contaminants. In order to speed up biodegradation, the environment is altered by introducing nutrients, electron acceptors, or other substrates to encourage the current microbial community.
Biostimulation aims to boost the metabolic processes of naturally occurring microorganisms, such as bacteria, that can break down pollutants.
By adding substances such as: Nutrients (e.g., N, P, trace minerals) ,Electron acceptors (e.g., oxygen, nitrate) ,Moisture or pH adjustments,the microbial metabolism is enhanced, leading to faster and more complete degradation of contaminants.
Examples of Biostimulation Applications:
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Oil spill cleanups: Adding fertilizers to stimulate hydrocarbon-degrading bacteria.
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Groundwater remediation: Injecting nutrients to promote microbial reduction of chlorinated solvents.
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Soil remediation: Adjusting pH and nutrient levels to aid biodegradation of organic pollutants.
7. Biostimulation vs. Bioaugmentation:
| Aspect | Biostimulation | Bioaugmentation |
|---|---|---|
| Microorganisms used | Native (indigenous) | Introduced (foreign or lab-grown) |
| Strategy | Enhance existing microbes | Add specific strains |
| Cost & risk | Lower | Higher (due to introduction of non-native species) |