Examples of bioremediation are; intrinsic microbial bioremediation of oil spill sites, phytostabilization of heavy metal-contaminated soil, and industrial wastewater bio-treatment.
This article discusses the examples of bioremediation, as follows;
1). Intrinsic Microbial Remediation of Oil Spill Sites (as one of the Examples of Bioremediation)
The pollutants present in oil spill sites are mostly hydrocarbons.
Intrinsic microbial remediation is simply the use of microbes already present on a site, to remove contaminants.
Alternatively referred to as 'in situ' remediation is one of the main types of bioremediation and is recommendable for cases where the native microorganisms are suitable to breakdown the contaminant effectively.
Intrinsic microbial remediation is also recommendable for cases where the degradation is not too severe or complex as to require multidimensional treatment measures.
Microorganisms that are used in bioremediation of oil spills include fungi like; Pleurotus tuber-regium, Lentinus squarrosulus and Pleurotus pulmonarius; bacteria like; Gordonia sp., Aeromonas hydrophila, Pseudomonas putida and Alcaligenes xylosoxidans; as well as algae.
Plants like Imperata cylindrica, Pteris vittata, Salicornia persica, Epipremnum aureumn, Bassia scoparia, Galega orientalis, and Mucuna bracteata can also be used for in situ phycoremediation of hydrocarbon pollution , although they often require supplementation by other biological tools and mechanisms.
Bacteria can be used to clean up an oil spill by creating conditions that facilitate the multiplication and increase in metabolic activities of bacteria on a hydrocarbon-polluted site; so that the hydrocarbons become subject to microbial breakdown, to yield byproducts like water and carbon dioxide, which do not pose any harm to the biological pyramid or ecosystem.
There have been many remediation projects around the world where microbes have been used to treat hydrocarbon contamination.
These projects have proven the effectiveness of the method, as well as its versatility for various geographic and hydrological conditions, including brackish wetland scenarios .
2). Phytostabilization of Heavy Metal-Contaminated Soil
As the term implies; phytostabilization is concerned with the use of plants to reduce the mobility of pollutants, which results in reduced rate of spread of environmental pollution and degradation .
Phytostabilization is particularly effective in scenarios where degradation is caused solely or mainly by heavy metals.
This is because of the tendency of heavy metals to be affected by plants in terms of their mobility and bioavailability.
The phytostabilization (immobilization) of heavy metals by plants is often accompanied phytoextraction, which is yet another mechanism of phytoremediation (or plant-based bioremediation).
It is recommendable to implement phytostabilization under ex situ conditions for cases of severe heavy metal pollution, alongside other remediation techniques like electrokinetic treatment, chemical washing, leaching and landfilling .
Among the above-listed methods, the most feasible for removal of heavy metals from contaminated soil is chemical washing, due to its versatility that makes it both applicable and effective under a variety of conditions .
Following immobilization or phytostabilization of heavy metals in soil or water, the remediation process requires that these pollutants are removed from the degraded medium through phytoextraction, whereby plants absorb the pollutants and/or facilitate their metabolic breakdown to yield non-toxic products.
To achieve effective phytostabilization, specific plant species that are described as hyper-accumulators (or hyperaccumulators) are required. Examples of such plants include; Alyssum bertolonii, Eichhornnia crassipes, and Thlaspi caerulescen; which can be effectively used to treat pollution cases involving iron (Fe), lead (Pb) and Manganese (Mn) among others.
3). Industrial Wastewater Bio-treatment (as one of the Examples of Bioremediation)
The three (3) main types of wastewater treatment are; physical, chemical and biological treatment.
For any given scenario, the types and/or methods selected are influenced by the type or source of wastewater to be treated; which could be municipal or industrial, among others.
Methods included in industrial wastewater treatment include; membrane filtration; coagulation, and controlled microbial breakdown. Of these, microbial breakdown is representative of biological treatment, since the process of biodegradation is used as a primary facilitator of pollutant removal.
Biological wastewater treatment process is the combination of steps involved in the restoration of water quality where biological materials and methods are utilized.
For industrial wastewater, biological treatment has immense importance in multiple contexts, including socioeconomic and environmental.
One of the reasons for this is that industrial wastewater bio-treatment serves as a form of recycling, of water resources in industries . Since recycling is an essential measure for sustainability, it can be argued that industrial wastewater bio-treatment is in alignment with the principles of sustainable development and circular economy.
While organic constituents are most-effectively removed through bio-treatment, all major types of pollutants in industrial wastewater can be degraded by microbes and biological processes.
When assessed based on the simultaneity or congruence of biological and chemical influences, biological wastewater treatment can be referred to alternatively as biochemical treatment.
The main biochemical treatment methods for wastewater are; aerobic and anaerobic methods; where aerobic treatment may occur in the form of bioventing, biofiltration, and use of rotational biological contactors; while anaerobic treatment includes all techniques that effectively isolate oxygen from wastewater during treatment .
Examples of bioremediation are;
1. Intrinsic Microbial Remediation of Oil Spill Sites
2. Phytostabilization of Heavy Metal-Contaminated Soil
3. Industrial Wastewater Bio-treatment
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