Bioremediation – Process and Types Explanation

Key Concepts

• What is Bioremediation?

• Explain the two types of Bioremediation:

1. In-situ
2. Ex-situ

• Discuss various techniques of Bioremediation:

• Explain :Bioventing, Biosparging, Biostimulation, Bioaugmentation, Landlarming, Composting, Bioreactors and Bio piling

Introduction:

In the 1960s, petroleum engineer George M. Robinson created modern bioremediation. He conducted studies using bacteria in glass jars containing contaminants.  

He experimented with several varieties of bacteria in the jars and discovered that certain types were effective at breaking down the contaminant. 

Bioremediation, on the other hand, is not a novel concept. It has been in commercial usage for almost two decades. In 1972, the first commercial in situ bioremediation system was constructed in Ambler, Pennsylvania, to clean up a Sun Oil pipeline accident. 

The scientists also knew that by adding the correct nutrients to the contaminated wells’ ground water, such as oxygen, nitrogen, and phosphate, the bacteria would multiply rapidly and eliminate the poisonous gasoline far faster and more efficiently than physical methods could. 

Before the 1980s, it was thought that bacteria could only breakdown petroleum hydrocarbons. However, later research revealed that some bacteria could also do the same in anaerobic, or oxygen free conditions. 

 Bioremediation is made up of two words: “bio” means “living,” and “remediate” means “to solve a problem. 

 Bioremediation is the technique of fixing a problem using living organisms such as microorganisms. 

It is a branch of biotechnology concerned with the removal of environmental toxins by the use of microorganisms, which are the primary biological agents. 

As a result, bioremediates are microorganisms that are employed to degrade contaminants. 

Nowadays, contaminants can be found in the food we eat, the water we drink and use in a variety of other activities, the air we breathe, and the land we live on. 

According to research conducted by the Environmental Protection Agency (EPA), just around 10% of garbage is properly disposed of.  

We can simply conclude how much pollution exists in our ecosystem from this. 

Munitions wastes, organic solvents, halogenated aromatic hydrocarbons, insecticides, and polyaromatic hydrocarbons are some of the most common pollutants (PAH). 

In bioremediation, three types of bacteria used are anaerobic, aerobic and filamentous bacteria and also some fungi. 

Factors affecting bioremediation and mechanism of bioremediation 

1. Microbial population for biological degradation. 

2. Availability of contaminants to degrade. 

3. Environmental factors such as nutrients, pH, temperature, presence of oxygen, a kind of soil, etc. 

Mechanism of bioremediation: 

Bioremediation’s process or working procedure is based on the activity of the microorganisms we use. 

For their growth and reproduction, those live creatures decompose and take organic compounds such as carbon, electrons, a supply of cell-building materials, and an energy source. 

The contaminants are first examined, then microorganisms are selected based on the elements present in order for them to easily digest the pollutants. 

The bacteria are analyzed, cultivated, and then released into the polluted environment. 

Furthermore, microorganisms multiply rapidly and eat all of the organic nutrients in the waste,  

converting them to carbon dioxide and water. 

The contaminated soil and water are treated with microbes and further soil and water that are degraded is placed in bed with oxygen and rich nutrients for more degradation. 

Two types of bioremediation: in-situ bioremediation and ex-situ bioremediation 

Explanation:

Bioventing:  

It is a method of encouraging natural in-situ biodegradation of pollutants in soil by supplying air or oxygen to soil microorganisms already present. 

Direct air injection into residual contamination in soil is the most prevalent method of supplying oxygen. 

Volatile chemicals are biodegraded as vapors move slowly through biologically active soil, in addition to absorbed fuel residuals. 

Biosparging: 

It consists of injecting pressurized air or gas into a contaminated zone in order to stimulate in situ aerobic biological activity. 

This technology targets chemical substances that can be biodegraded under aerobic conditions and is used to treat soluble and residual contaminants in the saturated zone. 

It is used to degrade the petroleum constituents dissolved in water and absorbed in the soil. 

Biostimulation: 

It is the process of altering the environment to encourage the growth of microorganisms capable of bioremediation. 

It refers to the addition of rate limiting nutrients like phosphorus, nitrogen, oxygen, electron donors to severely polluted sites to stimulate the existing bacteria to degrade the hazardous and toxic contaminants. 

Bioaugmentation: 

Bioaugmentation is the practice of adding cultured microbes into the soil or groundwater to enhance the rate of contaminant degradation. 

The addition of microbes with specific metabolic activities that are added to natural microbial populations will promote degradation of the contaminants. 

Similarities between bioaugmentation and biostimulation 

• Bioaugmentation and biostimulation are two ways for cleaning contaminated environments that are both sustainable. 

• Bioaugmentation can improve biostimulation. 
• Microorganisms are used in both procedures. 
• Both of the methods are biological. 
• Unlike chemical procedures, these methods do not produce hazardous byproducts and are not harmful. 
• Both strategies are receiving a lot of attention these days because of their promise and long-term viability. 

• They are long-term and promising solutions for the degradation of contaminated soil and water, as well as cost-effective alternatives to chemical techniques. 

Differences between biostimulation and bioaugmentation 

• Bioaugmentation is the addition of certain microbes to existing populations to enhance biodegradation, whereas biostimulation is the addition of electron acceptors, electron suppliers, or nutrients to boost naturally existent microbial populations in the environment. 
• Furthermore, foreign microorganisms are commonly utilized in bioaugmentation, whereas    indigenous microorganisms are commonly used in biostimulation. 

Ex-situ bioremediation: 

Landfarming: 

Contaminated soils are blended with soil amendments like bulking agents and fertilizers before being tilled into the ground in landfarming. 

Aeration is achieved by tilling the material on a regular basis.  

Microbiological and oxidative mechanisms degrade, convert, and immobilize contaminants. 

Land farming reduces concentrations of petroleum constituents through biodegradation. 

Composting: 

Compost bioremediation is the process of breaking down pollutants in water or soil using a biological system of microorganisms found in a mature, cured compost. 

In bioremediation, compost is referred to as “tailored” or “designed” compost since it is prepared specifically to treat certain toxins at specified locations. 

It involves the addition of non-hazardous organic compounds such as agricultural waste to contaminated soil. 

The presence of these organic components such as wood chips, hay, manure, and vegetative wastes supports the development of a rich microbial population. 

Proper amendment selection makes proper porosity and provides balance of carbon and nitrogen to enhance the microbial activity. 

Compost bioremediation is the process of breaking down pollutants in water or soil using a biological system of microorganisms found in a mature, cured compost. In bioremediation, compost is referred to as tailored or designed compost since it is prepared specifically to treat certain toxins at specified locations. It involves the addition of non-hazardous organic compounds such as agricultural waste to contaminated soil. The presence of these organic components such as wood chips, hay, manure, and vegetative wastes supports the development of a rich microbial population. Proper amendment selection makes proper porosity and provides balance of carbon and nitrogen to enhance the microbial activity. 

Biopiling: 

Biopiling is the process of assembling contaminated soils into piles and stimulating microbial populations’ biodegrading activity by creating near-optimal growth conditions. The excavated soil is piled up to 3 meters high and 6 meters wide in a lined area. 

A vacuum pump or an air injection blower system is used to aerate the pile. To limit emissions to the atmosphere, bio pile vapors can be collected and processed onsite using granular activated carbon (GAC) or an air bio-filter. 

Bioreactors: 

It is a manufactured device that supports a biologically active environment. The bioreactor is a huge vessel that is used to develop new biological products using various cells such as human, plant, or animal cells. It’s a closed container with enough aeration, agitation, temperature, and pH control, as well as a drain or overflow vent for removing the waste biomass of cultured microorganisms and their products. They are used for the production of biomass, metabolites, and antibiotics.  

The two types of bioreactors utilized for this purpose are the simple stirred-tank bioreactor and the sparged stirred-tank bioreactor. 

Summary

• Bioremediation is a method of treating contaminated media, including water, soil, and subterranean material, by modifying environmental conditions to encourage the growth of microorganisms that breakdown the contaminants.

• Bioremediation is a metabolic process that uses biological organisms to eliminate or neutralize an environmental pollutant.

• This can involve either aerobic or anaerobic micro-organisms that often use this breakdown as an energy source.

• It is cheaper than most cleanup methods because it does not require substantial equipment or labor.

• The factors that affect bioremediation are microbial population, types of contaminants, and physical factors such as pH, temperature, kind of soil, presence of oxygen, etc.

• Two types of bioremediations are: in-situ and ex-situ.

• In-situ bioremediation takes care of contaminated soil or groundwater right where it was discovered.

• Ex-situ bioremediation needs the contaminated water to be pumped out and the contaminated soil to be removed from the site.

• Bioventing is a process of stimulating the natural in-situ biodegradation of contaminants in soil by providing air or oxygen to existing soil microorganisms.

• Biosparging consists of injecting pressurized air or gas into a contaminated zone in order to stimulate in-situ aerobic biological activity.

• Biostimulation is the process of altering the environment to encourage the growth of microorganisms capable of bioremediation.

• Bioaugmentation is the practice of adding cultured microbes into the soil or groundwater to enhance the rate of contaminant degradation.

Ex-situ bioremediation:

• La ndfarming: Contaminated soil is blended with soil amendments like bulking agents and fertilizers before being tilled into the ground.

• Compost bioremediation is the process of breaking down pollutants in water or soil using a biological system of microorganisms found in a mature, cured compost.

• Biopiling is the process of assembling contaminated soils into piles and stimulating microbial populations’ biodegrading activity by creating near-optimal growth conditions.

• Bioreactors are closed containers with enough aeration, agitation, temperature, and pH control, as well as a drain or overflow vent for removing the waste biomass of cultured microorganisms and their products. They are used for the production of biomass, metabolites, and antibiotics.

• Microbes used in bioremediation of soil are bacteria – Achromobacter,Acinetobacter, Alcaligenes, Arthrobacter, Bacillus; Fungi – Rhodotorula, Mortierella, Aspergillus and Penicilliu rn,Trichoderma etc. Phenerochaete chrysosporium has wide degradative capacity due to production of lignases which utilizes peroxide.

• Bioremediation is cost efficient and helps chemical and physical methods of managing wastes and environmental pollutants. • Bioremediation will play an important role as a result of new and emerging techniques and processes.