Bioremediation: Overview, Process, Examples, Types, Topics

Any method in which a living or dead biological system (usually bacteria, microalgae, fungus, and plants) is used to remove environmental contaminants from the air, water, soil, flue gases, industrial effluents, etc., in natural or artificial settings is referred to as bioremediation. The utilization of biological resources in the remediation of contaminated settings has been drawn to the natural capacity of organisms to adsorb, accumulate, and degrade common and developing contaminants.

Bioremediation is scalable, affordable, sustainable, and environmentally friendly in contrast to traditional physiochemical treatment approaches, which have significant limitations. The majority of bioremediation is unintentional and involves native organisms. Research on bioremediation has a strong emphasis on accelerating the process by introducing organisms to a polluted site or providing nutrients to encourage development. The impact of byproducts produced by anthropogenic activities, such as industrialization and agricultural processes, might theoretically be lessened by bioremediation. Compared to other cleanup options, bioremediation may be more affordable and environmentally friendly.

Early users of low-cost bioremediation techniques include UNICEF, power companies, bulk water suppliers, and local governments. These techniques include aerobic bacteria tablets that are simply thrown into the water.

In general, organic contaminants are more prone to biodegradation than heavy metals. Oxidations are a common component of bioremediations. Oxidations increase the water solubility of organic molecules and make them more vulnerable to subsequent oxidation and hydrolysis-based breakdown. In the end, biodegradation reduces hydrocarbons to carbon dioxide and water. Bioremediation has limited options for dealing with heavy metals. Various bioremediation methods can eliminate or lessen a contaminant that contains metals.

The primary difficulty with bioremediations is their slow rate.

Types Of Bioremediation Methods

The two types of bioremediation methods are ex-situ methods, which are used on excavated materials, and (ii) in situ methods, which treat polluted sites directly. In both of these methods, extra nutrients, vitamins, minerals, and pH buffers are supplied to promote the bacteria's growth and metabolism. Specialized microbial cultures are occasionally added (biostimulation). Phytoremediation, bioventing, bioattenuation, biosparging, composting (biopiles and windrows), and land farming is a few examples of bioremediation-related technology.

Thermal desorption, vitrification, air stripping, bioleaching, rhizofiltration, and soil washing are further methods of remediation. An analogous method for treating pollutants, such as wastewater, industrial waste, and solid waste, is a biological treatment, or bioremediation. In order to improve the quality of soil and water, bioremediation ultimately aims to remove or minimize hazardous chemicals.

In situ Techniques -

Bioventing

By increasing the oxygen or airflow into the soil's unsaturated zone, a procedure known as bioventing speeds up the rate at which the targeted hydrocarbon contamination naturally degrades in the environment.

The most popular type of aerobic bioremediation, also known as bioventing, uses oxygen as an electron acceptor to oxidize pollutants like petroleum, polyaromatic hydrocarbons (PAHs), phenols, and other reduced pollutants. Because it produces more energy and is necessary for some enzyme systems to start the degradation process, oxygen is typically the preferred electron acceptor.

Microorganisms can break down a wide range of hydrocarbons, including components of gasoline, kerosene, diesel, and jet fuel. The biodegradation rates of the low- to moderate-weight aliphatic, alicyclic, and aromatic molecules can be extremely high under optimal aerobic conditions. Due to their large molecular weight and difficulty in being removed from the environment, volatile chemicals become more polluted as their resistance to biodegradation rises along with the compound's molecular weight.

Biostimulation

An illustration of biostimulation at Idaho's Snake River Plain Aquifer. Whey powder is added during this step to encourage the use of already existing microorganisms. Whey powder serves as a substrate to promote bacterial growth. As shown in earlier investigations, microorganisms at this location degrade the carcinogenic substance trichloroethylene (TCE).

The naturally occurring bacteria can perform bioremediation. In biostimulation, nutrients can be added to boost the population of these beneficial bacteria.

The degradation of hydrocarbons by bacteria is theoretically possible. Nitrogen and phosphorus have specifically proven important nutrients in the biodegradation of marine oil spills. Low rates are a problem for hydrocarbon bioremediation.

The microbial consortium may be involved in bioremediation. One species' output inside the consortium might serve as another species' substrate.

Bioattenuation

Biodegradation happens naturally with the addition of nutrients or microorganisms during bioattenuation. The metabolic activity will be determined by the local bacteria, which will also serve as a natural attenuator. The contaminated site needs to be monitored even though bioattenuation is not anthropogenically influenced.

Biosparging

Groundwater treatment with biosparging involves injecting oxygen and potential nutrients. Local bacteria are encouraged to accelerate the rate of breakdown when oxygen is added. Biosparging, which is primarily related to groundwater treatment, concentrates on saturated contaminated zones.

Ex situ techniques -

Biopiles

Petroleum pollution is reduced via biopiles, which work similarly to bioventing by adding aerobic hydrocarbons to contaminated soils. But an aeration system is used to excavate and pile the soil. By adding oxygen under positive pressure or removing it under negative pressure, this aeration device improves microbial activity.

Windrows

To lessen the oil-contaminated site of the former Shell Haven Refinery in Standford-le-Hope, bioremediation was used. Windrows, a bioremediation technique, was utilized to encourage oxygen transfer. About 115,000 m3 of polluted soil had been removed by the refinery.

Similar to composting procedures, windrow systems include turning the soil on a regular basis to improve aeration. This routine rotating also makes it possible for toxins to be evenly disseminated throughout the soil, speeding up the bioremediation process.

Landfarming

Sludge spills are frequently handled via land farming, also known as a land treatment. Through cyclical rotation, this technique spreads polluted dirt and aerates the soil. Because microbial activity needs to be promoted, contaminated soils must be shallow for this technique, which is applied above land. However, excavation of the soil to the surface is necessary if the pollution is more than 5 feet below the surface.

Other methods of Waste Management

Incineration

Wastes and other undesired materials are burned during this procedure. The organic waste is converted during burning into ash, flue gas, and heat. Ash is what's left of the waste's inorganic components. Thermal treatment is another name for it.

Phytoremediation

In this scenario, plants are directly used to clean up or contain contaminants in the soil. This method of bioremediation will help mitigate the environmental problem without the need to excavate the contaminant material and dispose of it elsewhere.