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Chapter

Bioremediation Techniques for

Polluted Environment: Concept,
Advantages, Limitations, and
Prospects
Indu Sharma

Abstract

Environmental pollution has been rising in the past few decades due to increased
anthropogenic activities. Bioremediation is an attractive and successful cleaning
technique 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. The main principle is
degrading and converting pollutants to less toxic forms. Bioremediation can be
carried out ex-situ and in-situ, depending on several factors, which include but not
limited to cost, site characteristics, type, and concentration of pollutants. Hence,
appropriate bioremediation technique is selected. Additionally, the major method-
ologies to develop bioremediation are biostimulation, bioaugmentation, bioventing,
biopiles, and bioattenuation provided the environmental factors that decide the
completion of bioremediation. Bioremediation is the most effective, economical,
eco-friendly management tool to manage the polluted environment. All bioreme-
diation techniques have its own advantage and disadvantage because it has its own
specific applications.

Keywords: bioremediation, environment, pollutants soil, ground water, waste-water,

applications, limitations

1. Introduction

Bioremediation and natural reduction are also seen as a solution for emerging
contaminant problems; microbes are very helpful to remediate the contaminated
environment. Number of microbes including aerobic, anaerobic bacteria and
fungi are involved in bioremediation process. 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. The main principle is degrading and converting
pollutants to less toxic forms. There are two types of factors these are biotic and
abiotic conditions are determine rate of degradation. Currently, different methods
and strategies are applied for bioremediation process.

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Trace Metals in the Environment - New Approaches and Recent Advances

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, herbi-
cides, 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 (biore-
mediation) 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 tech-
niques that restore polluted environments. The micro-organisms used in bioremedia-
tion 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

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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.

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).

3. Microorganisms used in bioremediation

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 microorgan-
isms 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 com-
plex compounds such as Pseudomonas, Acinetobacter, Sphingomonas, Nocardia,
Flavobacterium, Rhodococcus, and Mycobacterium. These microbes have been
reported to degrade pesticides, hydrocarbons, alkanes, and polyaromatic com-
pounds. 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
to less toxic forms.

3.1 Factors affecting microbial bioremediation

Bioremediation process is degrading, removing, changing, immobilizing, or

detoxifying various chemicals and physical pollutants from the environment through

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Trace Metals in the Environment - New Approaches and Recent Advances

the activity of bacteria, fungi, algae and plants. Enzymatic metabolic pathways of
microorganisms facilitate the progress of biochemical reactions that help in degrada-
tion of the pollutant. Microorganisms are act on the pollutants only when they have
contact to the compounds which help them to generate energy and nutrients to mul-
tiply cells. The effectiveness of bioremediation depends on many factors; including,
the chemical nature and concentration of pollutants, the physicochemical character-
istics of the environment, and their accessibility to existing microorganisms [4].
The factors are mainly microbial population for degrading the pollutants, the
accessibility of contaminants to the microbial population and environment factors
like type of soils, pH, temperature, oxygen and nutrients.

3.2 Biotic or biological factors

Biotic factors are helpful for the degradation of organic compounds by microor-
ganisms with insufficient carbon sources, antagonistic interactions among microor-
ganisms or the protozoa and bacteriophages. The rate of contaminant degradation
is frequently dependent on the concentration of the contaminant and the amount of
catalyst present in biochemical reaction. The major biological factors are included
enzyme activity, interaction (competition, succession, and predation), mutation,
horizontal gene transfer, its growth for biomass production, population size and its
composition [5, 6].

3.3 Abiotic or environmental factors

The interaction of environmental contaminants with metabolic activity, physi-

cochemical properties of the microorganisms targeted during the process. The
successful interaction between the microbes and pollutant depends on the environ-
mental situations. Microbial growth and activity are depended on temperature, pH,
moisture, soil structure, water solubility, nutrients, site conditions, oxygen content
and redox potential, deficiency of resources and physico-chemical bioavailability
of pollutants, concentration, chemical structure, type, solubility and toxicity. This
above factors are control degradation kinetics [5, 7].
Biodegradation of pollutant can occur under range of pH (6.5–8.5) is generally
optimal for biodegradation in most aquatic and terrestrial environment. Moisture
affects the metabolism of contaminant because it depends on the kind and amount
of soluble constituents that are accessible as well as the pH and osmotic pressure of
terrestrial and aquatic systems [8].

4. Bioremediation technique

Superficially, bioremediation techniques can be carried out ex-situ and in-situ

site of application (Figure 1). Pollutant nature, depth and amount of pollution,
type of environment, location, cost, and environmental policies are the selec-
tion standards that are considered for selecting any bioremediation technique.
Performance based on oxygen and nutrient concentrations, temperature, pH, and
other abiotic factors that determine the success of bioremediation processes [9, 10].
Ex-situ bioremediation techniques involve digging pollutants from polluted
sites and successively transporting them to another site for treatment. Ex-situ biore-
mediation techniques are regularly considered based on the depth of pollution, type
of pollutant, degree of pollution, cost of treatment and geographical location of the
polluted site. Performance standards also regulate the choice of ex-situ bioremedia-
tion techniques.

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

i. Solid-phase treatment

Solid-phase bioremediation is an ex-situ technology in which the contaminated

soil is excavated and placed into piles. It is also includes organic waste like leaves,
animal manures and agriculture wastes, domestic, industrial wastes and municipal
wastes. Bacterial growth is moved through pipes that are distributed throughout the
piles. Air pulling through the pipes is necessary for ventilation and microbial res-
piration. Solid-phase system required huge amount of space and cleanups require
more time to complete as compared to slurry-phase processes. Solid-phase treat-
ment processes include biopiles, windrows, land farming, composting, etc. [11].

ii. Slurry-phase bioremediation

Slurry-phase bioremediation is a relative more rapid process compared to the

other treatment processes. Contaminated soil is combined with water, nutrient and
oxygen in the bioreactor to create the optimum environment for the microorgan-
isms to degrade the contaminants which are present in soil. This processing involves
the separation of stones and rubbles from the contaminated soil. The added water
concentration depends on the concentration of pollutants, the biodegradation
process rate and the physicochemical properties of the soil. After completion of this
process the soil is removed and dried up by using vacuum filters, pressure filters
and centrifuges. The subsequent procedure is soil disposition and advance treat-
ment of the resultant fluids.

5. Types of bioremediations

There are far more than nine types of bioremediation, but the following are the
most common ways in which it is used.

5.1 Biopile

Bioremediation includes above-ground piling of dug polluted soil, followed by

aeration and nutrient amendment to improve bioremediation by microbial meta-
bolic activities. This technique comprises aeration, irrigation, nutrients, leachate
collection and treatment bed systems. This specific ex-situ technique is progres-
sively being measured due to its useful features with cost effectiveness, which
allows operative biodegradation conditions includes pH, nutrient, temperature and
aeration are effectively controlled. The biopile use to treat volatile low molecular
weight pollutants; it can also be used effectively to remediate polluted very cold
extreme environments [12–14]. The flexibility of biopile allows remediation time
to be shortened as heating system can be integrated into biopile design to increase
microbial activities and contaminant availability thus increasing the rate of biodeg-
radation [15]. Additionally, heated air can be injected into biopile design to deliver
air and heat in tandem, in order to facilitate enhanced bioremediation. Bulking
agents such as straw saw dust, bark or wood chips and other organic materials have
been added to enhance remediation process in a biopile construct. Although biopile
systems connected to additional field ex-situ bioremediation techniques, such
as land farming, bioventing, biosparging, robust engineering, maintenance and
operation cost, lack of power supply at remote sites, which would facilitate constant
air circulation in contaminated piled soil through air pump. Additional, extreme
heating of air can lead to soil drying undertaking bioremediation, which will inhibit
microbial activities and which stimulate volatilization than biodegradation [16].

5
Trace Metals in the Environment - New Approaches and Recent Advances

5.2 Windrows

Windrows is bioremediation techniques depends on periodic rotating the

piled polluted soil to improve bioremediation by increasing microbial degrada-
tion activities of native and transient hydrocarbonoclastic present in polluted soil.
The periodic turning of polluted soil increase in aeration with addition of water,
uniform distribution of nutrients, pollutants and microbial degradation activities,
accordingly increase the rate of bioremediation, which can be proficient through
acclimatization, biotransformation and mineralization. Windrow treatment as
compared to biopile treatment, showed higher rate of hydrocarbon removal how-
ever, the effectiveness of the windrow for hydrocarbon removal from the soil [17].
However, periodic turning associated with windrow treatment not the best selec-
tion method to implement in bioremediation of soil polluted with toxic volatiles
compounds. The use of windrow treatment has been associated in greenhouse gas
(CH4) release due to formation of anaerobic zone inside piled polluted soil, which
frequently reduced aeration [18].

5.3 Land farming

Land farming is the simplest, outstanding bioremediation techniques due to its

low cost and less equipment requirement for operation. It is mostly observed in ex-
situ bioremediation, while in some cases of in-situ bioremediation technique. This
consideration is due to the site of treatment. Pollutant depth is important in land
farming which can be carried out ex-situ or in-situ. In land farming, polluted soils
are regularly excavated and tilled and site of treatment speciously regulates the type
of bioremediation. When excavated polluted soil is treated on-site, it is ex-situ as it
has more in common than other ex-situ bioremediation techniques. Generally, exca-
vated polluted soils are carefully applied on a fixed layer support above the ground
surface to allow aerobic biodegradation of pollutant by autochthonous microorgan-
isms [19]. Over all, land farming bioremediation technique is very simple to design
and implement, requires low capital input and can be used to treat large volume of
polluted soil with minimal environmental impact and energy requirement [20].

5.4 Bioreactor

Bioreactor is a vessel in which raw materials are converted to specific product(s)

following series of biological reactions. There are different operational modes of
bioreactors, which include: batch, fed-batch, sequencing batch, continuous and
multistage. Bioreactor provides optimal growth conditions for bioremediation.
Bioreactor filled with polluted samples for remediation process. The bioreactor
based treatment of polluted soil has several advantages as compared to ex-situ
bioremediation procedures. Bioreactor-based bioremediation process having excel-
lent control of pH, temperature, agitation and aeration, substrate and inoculum
concentrations efficiently reduces bioremediation time. The ability to control and
manipulate process parameters in a bioreactor implies that biological reactions. The
flexible nature of bioreactor designs allows maximum biological degradation while
minimizing abiotic losses [21].
Advantages of ex-situ bioremediation

• Suitable for a wide range of contaminants

• Suitability relatively simple to assess from site investigation data

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

• Biodegradation are greater in a bioreactor system than or in solid-phase

systems because the contaminated environment is more manageable and more
controllable and predictable.

Disadvantages

• Not applicable to heavy metal contamination or chlorinated hydrocarbons such

as trichloroethylene.

• Non-permeable soil requires additional processing.

• The contaminant can be stripped from soil via soil washing or physical extrac-
tion before being placed in bioreactor.

5.4.1 In-situ bioremediation techniques

These techniques comprise treating polluted substances at the pollution site. It

does not need any excavation and by little or no disturbance in soil construction.
Perfectly, these techniques should to be cost effective compared to ex-situ biore-
mediation techniques. Some in-situ bioremediation techniques like bioventing,
biosparging and phytoremediation may be enhanced, while others may be progress
without any form of improvement such as intrinsic bioremediation or natural
attenuation. In-situ bioremediation techniques have been effectively used to treat
chlorinated solvents, heavy metals, dyes, and hydrocarbons polluted sites [22–24].

5.4.2 Types of in-situ bioremediation

In-situ bioremediation is two types; these are intrinsic and engineered

bioremediation.

i. Intrinsic bioremediation

Intrinsic bioremediation also known as natural reduction is an in-situ bioreme-

diation technique, which involves passive remediation of polluted sites, without
any external force (human intervention). This process deals with stimulation of
indigenous or naturally occurring microbial population. The process based on both
microbial aerobic and anaerobic processes to biodegrade polluting constituents
containing those that are recalcitrant. The absence of external force implies that the
technique is less expensive compared to other in-situ techniques.

ii. Engineered in-situ bioremediation

The second approach involves the introduction of certain microorganism to the

site of contamination. Genetically Engineered microorganisms used in the in-situ
bioremediation accelerate the degradation process by enhancing the physicochemi-
cal conditions to encourage the growth of microorganisms.

5.5 Bioventing

Bioventing techniques involve controlled stimulation of airflow by delivering

oxygen to unsaturated (vadose) zone in order to increase activities of indigenous
microbes for bioremediation. In bioventing, amendments are made by adding

7
Trace Metals in the Environment - New Approaches and Recent Advances

nutrients and moisture to increase bioremediation. That will achieve microbial

transformation of pollutants to a harmless state. This technique has gained popular-
ity among other in-situ bioremediation techniques [25].

5.6 Bioslurping

This technique combines vacuum-enhanced pumping, soil vapor extraction

and bioventing to achieve soil and ground water remediation by indirect providing
of oxygen and stimulation of contaminant biodegradation [26]. This technique is
planned for products recovery from remediating capillary, light non-aqueous phase
liquids (LNAPLs), unsaturated and saturated zones. This technique used to reme-
diate soils which are contaminated with volatile and semi-volatile organic com-
pounds. The method uses a “slurp” that spreads into the free product layer, which
pulls up liquids from this layer. The pumping machine transports LNAPLs to the
surface by upward movement, where it becomes separated from air and water. In
this technique, soil moisture bounds air permeability and declines oxygen transfer
rate, which reducing microbial activities. Although this technique is not suitable for
low permeable soil remediation, it is cost effective operation procedure due to less
amount of ground water, minimizes storage, treatment and disposal costs.

5.7 Biosparging

This technique is similar to bioventing in this air is injected into soil subsurface to
improve microbial activities which stimulate pollutant removal from polluted sites.
However, in bioventing, air is injected in saturated zone, which can help in upward
movement of volatile organic compounds to the unsaturated zone to stimulate
biodegradation process. The efficiency of biosparging depends on two major factors
specifically soil permeability and pollutant biodegradability. In bioventing and soil
vapor extraction (SVE), biosparing operation is closely correlated technique known
as in-situ air sparging (IAS), which depend on high air-flow rates for volatilization
of pollutant, whereas biosparging stimulates biodegradation. Biosparging has been
generally used in treating aquifers contaminated with diesel and kerosene.

5.8 Phytoremediation

Phytoremediation is depolluting the contaminated soils. This technique based on

plant interactions like physical, chemical, biological, microbiological and biochemi-
cal in contaminated sites to diminish the toxic properties of pollutants. Which is
depending on pollutant amount and nature, there are several mechanisms such as
extraction, degradation, filtration, accumulation, stabilization and volatilization
involved in phytoremediation. Pollutants like heavy metals and radionuclides are
commonly removed by extraction, transformation and sequestration. Organic pol-
lutants hydrocarbons and chlorinated compounds are mostly removed by degrada-
tion, rhizoremediation, stabilization and volatilization, with mineralization being
possible when some plants such as willow and alfalfa are used [27, 28].
Some important factors of plant as a phytoremediator include: root system, which
may be fibrous or tap depending on the depth of pollutant, above ground biomass,
toxicity of pollutant to plant, plant existence and its adaptability to predominant
environmental conditions, plant growth rate, site monitoring and above all, time
mandatory to achieve the preferred level of cleanliness. In addition, the plant must
be resistant to diseases and pests [29]. In phytoremediation removal of pollutant
includes uptake, translocation from roots to shoots. Further, translocation and
accumulation depends on transpiration and partitioning [30]. However, the process

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

is possible to change, depending on other factors such as nature of contaminant and

plant. The mostly plants growing in any polluted site are good phytoremediators.
Therefore, the success of any phytoremediation method mainly depends on improv-
ing the remediation potentials of native plants growing in polluted sites either by
bioaugmentation with endogenous or exogenous plant. One of the major advantages
of using plants to remediate polluted site is that some precious metals can bioaccumu-
late in some plants and recovered after remediation, a process known as phytomining.

5.9 Permeable reactive barrier (PRB)

This technique is commonly observed as a physical method for remediating

contaminated groundwater. However, biological mechanisms are precipitation
degradation and sorption of pollutant removal used in PRB method. The substitute
terms such as biological PRB, bio-enhanced PRB, passive bioreactive barrier, have
been suggested to accommodate the biotechnology and bioremediation aspect of
the technique. In general, PRB is an in-situ technique used for remediating heavy
metals and chlorinated compounds in groundwater pollution [31, 32].

5.10 Advantages of in-situ bioremediation

• In-situ bioremediation methods do not required excavation of the contami-

nated soil.

• This method provides volumetric treatment, treating both dissolved and solid
contaminants.

• The time required to treat sub-surface pollution using accelerated in-situ

bioremediation can often be faster than pump and treat processes.

• It may be possible to completely transform organic contaminants to innocuous

substances like carbon dioxide, water and ethane.

• It is a cost effective method because there is minimal site disruption.

5.11 Limitation of in-situ bioremediation

Depending on specific site, some contaminants may not be absolutely trans-

formed to harmless products.
If transformation stops at an intermediate compound, the intermediate may be
more toxic and/or mobile than parent compound some are recalcitrant contami-
nants cannot be biodegradable.
When incorrectly applied, injection wells may become blocked by profuse
microbial growth due to addition of nutrients, electron donor and electron acceptor.
Heavy metals and organic compounds concentration inhibit activity of indig-
enous microorganisms.
In-situ bioremediation usually required microorganism’s acclimatization, which
may not develop for spills and recalcitrant compounds.

6. Bioremediation prospects

Bioremediation techniques are varied and have demonstrated effective in

restoring polluted sites. Microorganisms play fundamental role in bioremediation;

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Trace Metals in the Environment - New Approaches and Recent Advances

consequently, their diversity, abundance and community structure in polluted

environments offer insight into the chance of any bioremediation technique provid-
ing other environmental factors, which can inhibit microbial activities. Advanced
Molecular techniques such as ‘Omics’ includes genomics, proteomics, metabolomics
and transcriptomics have contributed towards microbial identification, func-
tions, metabolic and catabolic pathways, with microbial based methods. Nutrient
availability, low population or absence of microbes with degradative capabilities,
and pollutant bioavailability may delay the achievement of bioremediation. Since
bioremediation depends on microbial process, biostimulation and bioaugmentation
approaches speed up microbial activities in polluted sites. Biostimulation increase
microbial activities by the addition of nutrients to a polluted sample. Microorganisms
are abundantly present in different type of environmental condition, it is noticeable
that pollutant degrading microbes are naturally present in polluted contaminated
sites, their growth and metabolic activities may depends on pollutant type and
concentration; later, we can use of agro-industrial wastes, which contains nitrogen,
phosphorus and potassium as a nutrient source most polluted sites. Microbial consor-
tium has been reported to degrade pollutants more efficiently than pure isolates [33].
This activity due to metabolic diversities of individual isolates, which potency create
from their isolation source, adaptation process, pollutant composition, and synergistic
effects, which may lead to complete and rapid degradation of pollutants when such
isolates are mixed together [34]. Additional so, both bioaugmentation and biostimula-
tion were effective in removing pollutant such as polyaromatic hydrocarbons (PAHs)
from heavily polluted sample compared to non-amended setup (control) [35].
Although bioaugmentation has recognized effective method, it has been shown
to increase the degradation of many compounds. If proper biodegrading micro-
organisms are not present in soil or if microbial populations decreased because of
contaminant toxicity, specific microorganisms can be added as “introduced organ-
isms” to improve the current populations and the possibility that the inoculated
microorganisms may not survive in the new environment make bioaugmentation a
very uncertain method. This process is known as bioaugmentation. Bioremediation
technique in which natural or genetically engineered bacteria with unique meta-
bolic profiles are used to treat sewage or contaminated water or soil. The use of
alginate, agar, agarose, gelatin, gellan gum and polyurethane as carrier materials
solve some of the challenges associated with bioaugmentation [36].
Biosurfactants are chemical equivalents having ecofriendly and biodegradable
properties. However, high construction cost and low scalability application of bio-
surfactants to polluted site are uneconomical. Agro-industrial wastes combination
are nutrient sources for development of biosurfactant producers during fermenta-
tion process. Application of several bioremediation techniques will help increase
remediation efficiency [37].
Enhancing bioremediation ability with organized use of genetically engineered
microorganisms (GEM) is a favorable approach. This is due to possibility of engi-
neering a designer biocatalyst target pollutant including recalcitrant compounds by
combining a novel and efficient metabolic pathways, widening the substrate range
of existing pathways and increasing stability of catabolic activity [38].
However, parallel gene transfer and multiplication of GEM in an environmental
application are encouraging approach. Bacterial containment systems, in which any
GEM escaping an environment to reconstruct polluted environment.
Further, derivative pathway of genetically engineering microorganisms with a
target polluted compound using biological approach could increase bioremedia-
tion efficiency. Nanomaterials decline the toxicity of pollutant to microorganisms
because nanomaterials having increase surface area and lower activation energy,
which reduce time and cost of bioremediation [39].

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7. Bioremediation applications

Bioremediation must be considered as appropriate methods that can applied to

all states of matter in the environment

i. Solids (soils, sediment and sludge)

ii. Liquids (ground water, surface water and industrial waste water

iii. Gases (industrial air emissions)

iv. Sub-surface environments (saturated and vadose zones).

The general approaches to bioremediation are the (i) intrinsic (natural) bio-
remediation, (ii) biosimulation (environmental modifications, through nutrient
application and aeration, and (iii) bioaugmentation (addition of microbes).
The biological community exploited for bioremediation generally consists of the
native soil microflora. However, higher plants can also be manipulated to enhance
toxicant removal (phytoremediation), especially for remediation of metal contami-
nated soils.

7.1 Advantage and disadvantage

All bioremediation techniques have its own advantage and disadvantage because
it has its own specific applications.

7.1.1 The advantage of bioremediation

• It is a natural process; it takes a little time, as an adequate waste treatment

process for contaminated material such as soil. Microbes able to degrade the
contaminant, the biodegradative populations become reduced. The treatment
products are commonly harmless including cell biomass, water and carbon
dioxide.

• It needs a very less effort and can commonly carry out on site, regularly with-
out disturbing normal microbial activities. This also eradicates the transport
amount of waste off site and the possible threats to human health and the
environment.

• It is functional in a cost effective process as comparison to other conven-

tional methods that are used for clean-up of toxic hazardous waste regularly
for the treatment of oil contaminated sites. It also supports in complete
degradation of the pollutants; many of the toxic hazardous compounds
can be transformed to less harmful products and disposal of contaminated
material.

• It does not use any dangerous chemicals. Nutrients especially fertilizers added
to make active and fast microbial growth. Because of bioremediation change
harmful chemicals into water and harmless gases, the harmful chemicals are
completely destroyed.

• Simple, less labor intensive and cheap due to their natural role in the
environment.

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Trace Metals in the Environment - New Approaches and Recent Advances

• Contaminants are destroyed, not simply transferred to different

environmental.

• Nonintrusive, possibly allowing for continued site use.

• Current way of remediating environment from large contaminates and acts as

ecofriendly sustainable opportunities.

7.1.2 The disadvantage of bioremediation

• It is restricted for biodegradable compounds. Not all compounds are disposed

to quick and complete degradation process.

• There are particular new products of biodegradation may be more toxic than
the initial compounds and persist in environment.

• Biological processes are highly specific, ecofriendly which includes the pres-
ence of metabolically active microbial populations, suitable environmental
growth conditions and availability of nutrients and contaminants.

• It is demanding to encourage the process from bench and pilot-scale to large-

scale field operations. Contaminants may be present as solids, liquids and
gases. It often takes longer than other treatment preferences, such as excava-
tion and removal of soil or incineration.

• Research is needed to develop and engineer bioremediation technologies that

are appropriate for sites with complex mixtures of contaminants that are not
evenly dispersed in the environment.

7.2 Limitations of bioremediation

Bioremediation is limited to those compounds that are biodegradable. This

method is susceptible to rapid and complete degradation. Products of biodegrada-
tion may be more persistent or toxic than the parent compound in the environment.

1. Specificity

Biological processes are highly specific. Important site factors mandatory for
success include the presence of metabolically capable microbial populations,
suitable environmental growth conditions, and appropriate levels of nutrients and
contaminants.

2. Scale up limitation

It is difficult to scale up bioremediation process from batch and pilot scale stud-
ies applicable to large scale field operations.

3. Technological advancement

More research is required to develop modern engineer bioremediation technolo-

gies that are suitable for sites with composite combinations of contaminants that are
not equally distributed in the environment. It may be present as solids, liquids and
gases forms.

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

4. Time taking process

Bioremediation takes longer time compare to other treatment options, such as

excavation and removal of soil from contaminated site.

5. Regulatory uncertainty

We are not certain to say that remediation is 100% completed, as there is no

accepted definition of clean. Due to that performance evaluation of bioremediation
is difficult, and there is no acceptable endpoint for bioremediation treatments.

8. Conclusion

Biodegradation is very fruitful and attractive option to remediating, cleaning,

managing and recovering technique for solving polluted environment through
microbial activity. The speed of undesirable waste substances degradation is
determined in competition with in biological agents like fungi, bacterial, algae inad-
equate supply with essential nutrient, uncomfortable external abiotic conditions
(aeration, moisture, pH, temperature), and low bioavailability. Bioremediation
depending on several factors, which include but not limited to cost, site character-
istics, type and concentration of pollutants. The leading step to a successful biore-
mediation is site description, which helps create the most suitable and promising
bioremediation technique (ex-situ or in-situ). Ex-situ bioremediation techniques
tend to be more costly due to excavation and transportation from archeological site.
However, they can be used to treat wider range of pollutants. In contrast, in-situ
techniques have no extra cost for excavation; however, on-site installation cost of
equipment, attached with effectively and control the subsurface of polluted site can
reduce some ineffective in-situ bioremediation methods. Geological characteristics
of polluted sites comprising soil, pollutant type and depth, human habitation
site and performance of every bioremediation technique should be integrated
in determining the most appropriate and operative bioremediation technique to
successfully treatment of polluted sites.

Author details

Indu Sharma
Department of Biotechnology, Maharishi Markandeshwar (Deemed to be
University), Mullana, Ambala, Haryana, India

*Address all correspondence to: endusharma@gmail.com

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms
of the Creative Commons Attribution License (http://creativecommons.org/licenses/
by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,
provided the original work is properly cited.

13
Trace Metals in the Environment - New Approaches and Recent Advances

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