**2. Environmental pollution**

Environmental pollution has been on the rise in the past few decades due to increased human activities such as population explosion, unsafe agricultural practices, unplanned urbanization, deforestation, rapid industrialization and non-judicious use of energy reservoirs and other anthropogenic activities. Among the pollutants that are of environmental and public health concerns due to their toxicities are: chemical fertilizer, heavy metals, nuclear wastes, pesticides, herbicides, insecticides greenhouse gases, and hydrocarbons. Thousands of hazardous waste sites have been identified and estimated is that more will be identified in the coming decades. Release of pollutants into the environment comes from illegal dumping by chemical companies and industries. Many of the techniques utilized for site clean-up in the past, such as digging up the contaminated soil and hauling it away to be land filled or incinerated have been prohibitively expensive and do not provide permanent solution. More recent techniques such as vapor extraction and soil venting are cost effective but incomplete solution.

### **2.1 Definition of bioremediation**

Bioremediation is a process where biological organisms are used to remove or neutralize an environmental pollutant by metabolic process. The "biological" organisms include microscopic organisms, such as fungi, algae and bacteria, and the "remediation"—treating the situation.

In the Earth's biosphere, microorganisms grow in the widest range of habitats. They grow in soil, water, plants, animals, deep sea, and freezing ice environment. Their absolute numbers and their appetite for a wide range of chemicals make microorganisms the perfect candidate for acting as our environmental caretakers.

*"Bioremediation is a waste management technique that includes the use of living organisms to eradicate or neutralize pollutants from a contaminated site."*

*"Bioremediation is a 'treatment techniques' that uses naturally occurring organisms to break down harmful materials into less toxic or non-toxic materials."*

#### **2.2 Bioremediation**

Bioremediation technologies came into extensive usage and continue growing today at an exponential rate. Remediation of polluted sites using microbial process (bioremediation) has proven effective and reliable due to its eco-friendly features. In the past two decades, there have been recent developments in bioremediation techniques with the decisive goal being to successfully restore polluted environments in an economic, eco-friendly approach. Researchers have developed different bioremediation techniques that restore polluted environments. The micro-organisms used in bioremediation can be either indigenous or non-indigenous added to the contaminated site. Indigenous microorganisms present in polluted environments hold the key to solving most of the challenges associated with biodegradation and bioremediation of pollutant [1]. Environmentally friendly and cost effective are among the major advantages of bioremediation compared to both chemical and physical methods of remediation.

A mechanism of bioremediation is to reduce, detoxify, degrade, mineralize or transform more toxic pollutants to a less toxic. The pollutant removal process depends mainly on the pollutant nature, which includes pesticides, agrochemicals, chlorinated compounds, heavy metals, xenobiotic compounds, organic halogens, greenhouse gases, hydrocarbons, nuclear waste, dyes plastics and sludge. Cleaning

**223**

to less toxic forms.

**Figure 1.**

*Bioremediation Techniques for Polluted Environment: Concept, Advantages, Limitations…*

technique apply to remove toxic waste from polluted environment. Bioremediation is highly involved in degradation, eradication, immobilization, or detoxification diverse chemical wastes and physical hazardous materials from the surrounding

Microorganisms play an important role on nutritional chains that are important part of the biological balance in life. Bioremediation involves the removal of the contaminated materials with the help of bacteria, fungi, algae and yeast. Microbes can grow at below zero temperature as well as extreme heat in the presence of hazardous compounds or any waste stream. The two characters of microbes are adaptability and biological system made them suitable for remediation process [2]. Carbon is the main requirement for microbial activity. Bioremediation process was carried out by microbial consortium in different environments. These microorganisms comprise *Achromobacter*, *Arthrobacter*, *Alcaligenes*, *Bacillus*, *Corynebacterium*, *Pseudomonas, Flavobacterium*, *Mycobacterium*, *Nitrosomonas*, *Xanthobacter*, etc. [3]. There are groups of microbes which are used in bioremediation such as: **Aerobic:** aerobic bacteria have degradative capacities to degrade the complex compounds such as *Pseudomonas, Acinetobacter, Sphingomonas, Nocardia, Flavobacterium, Rhodococcus*, and *Mycobacterium.* These microbes have been reported to degrade pesticides, hydrocarbons, alkanes, and polyaromatic compounds. Many of these bacteria use the contaminants as carbon and energy source**. Anaerobic:** anaerobic bacteria are not as regularly used as aerobic bacteria. There is an increasing interest in aerobic bacteria used for bioremediation of

chlorinated aromatic compounds, polychlorinated biphenyls, and dechlorination of the solvent trichloroethylene and chloroform, degrading and converting pollutants

Bioremediation process is degrading, removing, changing, immobilizing, or detoxifying various chemicals and physical pollutants from the environment through

through the all-inclusive and action of microorganisms (**Figure 1**).

**3. Microorganisms used in bioremediation**

*Bioremediation approaches for environmental clean-up.*

**3.1 Factors affecting microbial bioremediation**

*DOI: http://dx.doi.org/10.5772/intechopen.90453*

*Bioremediation Techniques for Polluted Environment: Concept, Advantages, Limitations… DOI: http://dx.doi.org/10.5772/intechopen.90453*

**Figure 1.** *Bioremediation approaches for environmental clean-up.*

*Trace Metals in the Environment - New Approaches and Recent Advances*

soil venting are cost effective but incomplete solution.

Environmental pollution has been on the rise in the past few decades due to increased human activities such as population explosion, unsafe agricultural practices, unplanned urbanization, deforestation, rapid industrialization and non-judicious use of energy reservoirs and other anthropogenic activities. Among the pollutants that are of environmental and public health concerns due to their toxicities are: chemical fertilizer, heavy metals, nuclear wastes, pesticides, herbicides, insecticides greenhouse gases, and hydrocarbons. Thousands of hazardous waste sites have been identified and estimated is that more will be identified in the coming decades. Release of pollutants into the environment comes from illegal dumping by chemical companies and industries. Many of the techniques utilized for site clean-up in the past, such as digging up the contaminated soil and hauling it away to be land filled or incinerated have been prohibitively expensive and do not provide permanent solution. More recent techniques such as vapor extraction and

Bioremediation is a process where biological organisms are used to remove or neutralize an environmental pollutant by metabolic process. The "biological" organisms include microscopic organisms, such as fungi, algae and bacteria, and the

In the Earth's biosphere, microorganisms grow in the widest range of habitats. They grow in soil, water, plants, animals, deep sea, and freezing ice environment. Their absolute numbers and their appetite for a wide range of chemicals make microorganisms the perfect candidate for acting as our environmental caretakers.

*"Bioremediation is a waste management technique that includes the use of living organisms to eradicate or neutralize pollutants from a contaminated site."*

*"Bioremediation is a 'treatment techniques' that uses naturally occurring organisms* 

Bioremediation technologies came into extensive usage and continue growing today at an exponential rate. Remediation of polluted sites using microbial process (bioremediation) has proven effective and reliable due to its eco-friendly features. In the past two decades, there have been recent developments in bioremediation techniques with the decisive goal being to successfully restore polluted environments in an economic, eco-friendly approach. Researchers have developed different bioremediation techniques that restore polluted environments. The micro-organisms used in bioremediation can be either indigenous or non-indigenous added to the contaminated site. Indigenous microorganisms present in polluted environments hold the key to solving most of the challenges associated with biodegradation and bioremediation of pollutant [1]. Environmentally friendly and cost effective are among the major advantages of bioremediation compared to both chemical and physical methods of remediation. A mechanism of bioremediation is to reduce, detoxify, degrade, mineralize or transform more toxic pollutants to a less toxic. The pollutant removal process depends mainly on the pollutant nature, which includes pesticides, agrochemicals, chlorinated compounds, heavy metals, xenobiotic compounds, organic halogens, greenhouse gases, hydrocarbons, nuclear waste, dyes plastics and sludge. Cleaning

*to break down harmful materials into less toxic or non-toxic materials."*

**2. Environmental pollution**

**2.1 Definition of bioremediation**

"remediation"—treating the situation.

**2.2 Bioremediation**

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technique apply to remove toxic waste from polluted environment. Bioremediation is highly involved in degradation, eradication, immobilization, or detoxification diverse chemical wastes and physical hazardous materials from the surrounding through the all-inclusive and action of microorganisms (**Figure 1**).
