Biodegradation is the digestion or breakdown of any complex compounds into simpler molecules with the help of living organisms that occurs naturally.
With new technologies being developed, humans have tried to make complex compounds that can last longer, and are more durable, disease-resistant, and recalcitrant than natural compounds. These qualities make them hazardous to living beings, disrupting the proper functioning of the food chain and accumulating in the ecosystem. Microorganisms like bacteria, yeast, fungi, micro plants, etc., have proven very effective in degrading toxicants like plastics, pesticides, xenobiotics, heavy metals, and more. Their exceptional capabilities of adjusting to the surrounding and genetic machinery have helped to provide solutions for the degradation of pollutants.
Bioremediation is a process of degradation of environmental contaminants by microbial consortia via a man-made engineered execution plan to get the desired product.
Bioremediation employs two modes of degradation process that are ex-situ and in-situ techniques, based on pollutant type, contamination depth in the soil, environmental conditions, equipment cost, and manpower. These techniques are keenly controlled and analyzed by a group of experts. The bioremediation technique is employed to get a predictable result by regulating the factors of execution design.
6 Key Differences between Biodegradation and Bioremediation
|Definition||Any degradation process that biologically transforms any complex compounds (organic and inorganic) into simpler and stable forms with the help of microorganisms’ enzymatic machinery.||A man-made remediation process that uses microbial fauna and environmental factors to reduce and eliminate complex and hazardous ecological pollutants.|
|Principle||It solely depends on the metabolic capabilities of the microorganisms to progressively convert hazardous contaminants to soluble and stable compounds.||Based on the degradative capabilities of microbes but also on the factors such as temperature, nutrient supplements, aeration, and more, controlled by humans that help in enhancing the remediation process|
|Type of Process||Self-paced, naturally occurring process.||An artificially engineered remediation process employing microorganisms.|
|Time||It is a slow-paced process since it requires time to transform contaminants into water and carbon dioxide completely.||Fast-paced process dealing with the transformation of pollutants into a stable form.|
|Human Intervention||Human intervention is not required, as it is a natural process.||Experts and Scientists carefully design the execution plan to monitor and analyze in order to get the desired result.|
|Technological Requirement||No need for technical equipment to carry out the degradation process by microorganisms.||Technical setup with expert guidance is needed to carry out the remediation process.|
Examples of Biodegradation Materials
Examples of biodegradation include the degradation of pollutants that are complex and toxic via different mechanical approaches. Most materials are biodegradable, which will eventually break down into their elemental forms. Each matter has its unique chemical and physical properties that determine the duration and how they’ll break down. The breakdown carried out by the microorganisms is done either aerobically or anaerobically, depending on the presence of oxygen around the polluted site.
Polyaromatic Hydrocarbons (PAH)
- They come under the class of Persistent Organic Pollutants (POPs) that occurs naturally in crude oil, gasoline, and coal.
- They are released into the environment by burning wood, garbage, coal, and tobacco, and also while cooking in high flame.
- Examples include naphthalene, pyrene, fluorene, anthracene, and more.
- Humans are constantly exposed to toxicants like PAHs which can cause irritation in the nasal passage and the eyes and, in severe cases, may lead to cancer.
- Hence their degradation is important for the overall balance of the ecosystem.
- Plastics have acquired usefulness in every aspect of life owing to their wide range of applications has led to their accumulation in the environment.
- Plastic refers to any polymer with a high molecular weight made by humans.
- Examples include polystyrene, polyethylene, polyvinyl chloride, and polypropylene.
- Microorganisms are able to digest plastics into a stable form by using it as a substrate in their highly specific enzymatic machinery.
Heavy metals include arsenic, cobalt, cadmium, nickel, and many more. These metals cannot be degraded but can be transformed into an elemental form. Heavy metals, because of their inability to degrade gets, accumulate in the environment. Microorganisms use these metals as electron acceptors to bring about metabolic processes.
Pesticides were invented to improve crop quality and disease-resistant plants and enhance production rates. But mismanagement of their heavy use led to their accumulation in the aquatic and terrestrial bodies, causing harm to the indigenous species. And the use of microbes seems a great approach for degradation. Examples include DDT, boric acid, glyphosate, malathion, etc.
Bioremediation Process Examples
Bioremediation processes are carried out by employing any of the applications – ex-situ or in-situ techniques based on the pollution site. Many factors dictate the selection of remediation techniques. Abiotic factors such as temperature, pH, site of contamination, oxygen availability, and biotic factors like pollutant nature and microbes’ degradative capabilities determine the type of technique administered. Additional factors such as environmental policies, type of equipment, and cost of execution also help in the technique selection process.
These techniques involve the transportation of pollutants to a new location for treatment by digging up the pollutants from the contaminated site. This concept is considered on the basis of pollutant type, depth of pollution, geographical location, and the treatment cost for the contaminated site.
Ex-situ Techniques Examples
- Biopiling– It is simply referred to as the piling up of excavated contaminated soil above ground in a different location. Nutrient supplementation and aeration are provided to enhance the activities of microbial degradation.
- Windrow – This technique relies on the regular periodic turning of excavated piled contaminant soil to speed up bioremediation. The turning added with water enhances the uniform distribution of nutrients, pollutants, and aeration, increasing microbial degradation.
- Bioreactor– As the name suggests, bioreactors are vessels in which excavated raw materials are transformed into a specific product under conditions that mimic the natural environment for optimum microbial growth.
- Land Farming– When pollutants are treated on-site above ground on a fixed layer support to allow autochthonous microorganisms to carry out the effective remediation process.
Benefits of Ex-situ Techniques
- Wide range of contaminants can be remediated.
- Easy to analyze and access the investigative data from the ex-situ site.
- In the bioreactor technique, factors can be regularly managed and regulated to access the desired product.
Limitations of Ex-situ Techniques
- Not suitable for contaminants such as heavy metals (As, Co, Zn, etc) and chlorinated hydrocarbons like trichloroethylene.
- Additional requirement of manual labor, transportation, and processing of bioremediation.
- The washing away of pollutants from contaminated soil during processes like transportation or physical extraction.
The treatment of contaminated soil at the pollution site without the need for excavation and disturbance to the soil construction. The techniques include bio-sparging, bioslurping, phytoremediation, and bioventing. They have been exclusively employed to treat heavy metals, dyes, and chlorinated compounds.
In-situ Techniques Examples
- Bioventing– The techniques incorporate regulated airflow stimulation to the polluted site, increasing the uniform distribution of oxygen available to the microbial population for aerobic degradation in the unsaturated land zone.
- Bioslurping– This technique uses the principle of capillary action where soil vapor extraction, vacuum-pumping, and bioventing to redistribute vapor and gases between saturated and unsaturated zones.
- Biosparging– This technique also uses airflow injection as in bioventing but in the saturation zone to promote the upward flow of volatile organic compounds to the unsaturation zone for biodegradation.
- Phytoremediation– This technique uses plants present in the contaminated sites, which helps to mitigate the toxic effects of contaminants via incorporating mechanisms like accumulation, extraction, volatilization, and more.
Benefits of In-situ Techniques
- No need for excavation of contaminated soil and transportation process.
- Solid and dissolved pollutants can be easily treated.
- Cost-effective method due to minimal site disruption.
Limitations of In-situ Techniques
- Formation of an intermediate compound that can be recalcitrant due to the inability to completely transform into harmless compounds.
- Injection wells may get blocked due to the proliferation of microbial population with the addition of nutrients.
- Inhibition of microbial growth and degradative activities can occur with increased concentration of xenobiotics and heavy metals.
Biodegradation is a naturally occurring process, while bioremediation is a man-made engineered process to degrade toxic environmental compounds.
The end goal of both processes is the same: the conversion of complex toxic compounds into stable, simpler forms that are harmless to the environment and can be used by living organisms as carbon and energy sources. Bioremediation employs several techniques based on factors like geographical location, type of pollutant, depth of contaminant in the soil, cost of execution, and more. The common factor between both processes is the presence of microorganisms and their metabolic machinery to degrade pollutants. These processes help nature to get rid of hazardous compounds that are released into the environment because of human activities and aim for sustainable development.
- Difference Between Biodegradation and Bioremediation – https://biodifferences.com/difference-between-biodegradation-and-bioremediation.html
- What is the Difference Between Biodegradation and Bioremediation – https://pediaa.com/what-is-the-difference-between-biodegradation-and-bioremediation/
- What is Biodegradation – Explained – https://www.mynusco.com/biodegradation-explained/
- Approaches for Removal of PAHs in Soils: Bioaugmentation, Biostimulation and Bioattenuation – https://www.intechopen.com/chapters/51942
- Difference between biodegradation and bioremediation – https://microbenotes.com/biodegradation-and-bioremediation/
- Bioremediation Techniques for Polluted Environment: Concept, Advantages, Limitations, and Prospects – https://www.intechopen.com/chapters/70661
- Azubuike, Christopher Chibueze, Chioma Blaise Chikere, and Gideon Chijioke Okpokwasili. “Bioremediation techniques–classification based on site of application: principles, advantages, limitations and prospects.” World Journal of Microbiology and Biotechnology 32 (2016): 1-18.
- Pesticide Biodegradation: Mechanisms, Genetics and Strategies to Enhance the Process – https://www.intechopen.com/chapters/45111
- Sayqal, Ali, and Omar B. Ahmed. “Advances in heavy metal bioremediation: an overview.” Applied Bionics and Biomechanics 2021 (2021).
- Biodegradability of Plastics – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2769161/
- Sahoo, Biswa M., et al. “Polyaromatic hydrocarbons (PAHs): structures, synthesis and their biological profile.” Current Organic Synthesis 17.8 (2020): 625-640.
- Polycyclic Aromatic Hydrocarbons (PAHs) Factsheet – https://www.cdc.gov/biomonitoring/PAHs_FactSheet.html
- Pesticides – https://byjus.com/chemistry/pesticides/