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BIOREMEDIATION AND "GREEN CHEMISTRY"

April 2019
Fresenius environmental bulletin 28(4A/2019):3056-3064

April 2019
28(4A/2019):3056-3064

Authors:

Bioremediation is basically a process which represents the ability of microorganisms to decompose different dangerous contaminants, and it has an increasingly key role in detoxification of contaminated soil and groundwater. These processes are getting their place owing to capacity of enzyme metabolism of microorganisms to transform organic contaminants into pollutants and less dangerous compounds. But, we should not forget that this method cannot always be applied. Among the available options for purification of contaminated soils, bioremediation is the best because it is less disturbing to environment and from the economic point of view-it costs less.

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3056

BIOREMEDIATION AND "GREEN CHEMISTRY"

Stevan Canak1, Ljiljana Berezljev2, Krstan Borojevic3, Jasminka Asotic4, Sonja Ketin5,*

1State University of Novi Pazar, Vuka Karadzica bb, 36300 Novi Pazar, Serbia

2 Faculty of Project and Innovation Management, Educons University, Vojvode Putnika bb, Sremska Kamenica, 21208 Novi Sad, Serbia

3International University Travnik, Aleja Konzula-Meljanac bb, 72270 Travnik, Bosnia and Herzegovina

4Faculty of Pharmacy and Health, Slavka Gavrancica 17c, 72270 Travnik, Bosnia and Herzegovina

5Faculty of Maritime Academic Studies Belgrade, Bulevar Vojvode Misica 37, 11000 Belgrade, Serbia

ABSTRACT

Bioremediation is basically a process which

represents the ability of microorganisms to decom-

pose different dangerous contaminants, and it has

an increasingly key role in detoxification of con-

taminated soil and groundwater. These processes

are getting their place owing to capacity of enzyme

metabolism of microorganisms to transform organic

contaminants into pollutants and less dangerous

compounds. But, we should not forget that this

method cannot always be applied. Among the

available options for purification of contaminated

soils, bioremediation is the best because it is less

disturbing to environment and from the economic

point of view-it costs less.

KEYWORDS:

Land, pollution, bioremediation, microorganisms

INTRODUCTION

With the industrial revolution there has been

intensive human impact on nature and the world

around him. The level of environmental awareness

was very low, and pursued as far as productivity

and cost-effectiveness, which did not take into ac-

count the distortion of the natural balance and now

the necessary means to eliminate the negative con-

sequences of industrialization, if it is still possible.

According to the policy of sustainable development

technology development should be in the direction

of eliminating the negative effects to the environ-

ment. However, not all countries are in a financial

position that in due time to leave old technologies.

Also, nowadays are present the consequences of the

operation and need to be eliminated. The twentieth

century will be remembered as the century of the

oil. With the emergence of oil as a fuel has been the

most intense economic growth and the entire mod-

ern civilization is based on the use of oil [1, 2, 22].

The green chemistry is the scientific field that

involves chemical research and engineering, whose

focus is to promote the design of products and pro-

cesses that minimize the use and formation of haz-

ardous substances. While the chemistry of the envi-

ronment is dealing with the natural environment

and chemical pollution in nature, the green chemis-

try aims to decrease and prevent the formation of

contamination at its sources. In the form of chemi-

cal philosophy, the green chemistry is applicable to

organic chemistry, inorganic chemistry, biochemis-

try, analytical chemistry, and even physical chemis-

try. The focus of the green chemistry is on industri-

al applications, regardless of the type. Click of

chemistry is often cited as a style of chemical syn-

thesis that is consistent with the goals of green

chemistry. The objective is minimization of hazards

and maximization of efficiency. Examples of key

events in green chemistry are: the use of supercriti-

cal CO2 as green solvents, the use of an aqueous

solution of hydrogen peroxide to clean the oxida-

tion and the use of hydrogen in asymmetric synthe-

sis. Green chemistry is used in the supercritical

water oxidation reactions in water, and reactions in

the solid state.

Bio-remediation technology is a selective

method that least disturbs the environment, particu-

larly in the application of in situ and corresponds to

the strategy of sustainable development in the eco-

system security. The effectiveness of bioremedia-

tion of land depends on a number of parameters:

environmental factors, additive and availability of

nutrients and the technical characteristics of the

plants. However, under optimal conditions for de-

contamination, the process does not remove all the

contaminants, but the effectiveness and economic

viability of bio-process depends on the identifica-

tion of critical factors and their optimization.

METHODS AND MATERIALS

Biological methods of decontamination. Bi-

ological methods are applied on land contaminated

with radio-nuclides and can be used in combination

with other methods. The most common used biore-

mediation processes for this pollutant are: biotrans-

formation - where the contaminated molecules are

converted into less hazardous or non-hazardous

molecules; biodegradation - where the organic sub-

stance are destroy the smaller organic and inorganic

3057

molecules; Biomineralization - where they are de-

graded by organic materials to inorganic, such as

CO2 and H2O. All three processes can be applied in

situ and ex situ. Strategies that are recommended

for the removal of metals and radionuclides include

microbial leaching, microbial surfactants, volati-

lization and bioaccumulation.

In any case, bioremediation processes are pro-

vided by the same as those that occur in nature.

Depending on the location and contaminants, bio-

remediation may be safer and less expensive than

alternative technologies such as incineration and

landfilling. It can also be applied to phytoremedia-

tion, which involves the use of plants for extraction,

sequestration and/or detoxification of pollutants

that are present in the soil.

This method is considered the cheapest and

simplest cleaning area. Also, the plants can be used

to monitor the effects of soil remediation. This ap-

plies to plants with great potential for the accumula-

tion of heavy metals and radionuclides, but when it

comes to food for human consumption, it can be

dangerous if it contains these dangerous substances

[3-5].

The mechanisms of phytoremediation:

▪ Phytostabilization - includes the use of

plants containing/immobilizing pollutants through-

out: the absorption and accumulation by means of

the root system, to adsorb onto the surface of the

root and the precipitation in the root zone;

▪ Phytodegradation/phytotransformation –

including decomposition of pollutants through:

metabolic processes (internal) and release enzymes

into the soil;

▪ Phytovolatization - absorption and transpi-

ration of pollutants into the atmosphere by using of

plants;

▪ Rhizodegradation – decomposition of pol-

lutants in the soil due to the interaction of mi-

crobes/root/soil;

▪ Phytohydraulics – involves the use of

plants to monitor the migration of contaminants.

Definition and the way of functioning of the

bioremediation. Bioremediation is a process that

uses microorganisms for removal or degradation of

toxic substances into less toxic or non-toxic sub-

stances. In this process, the microorganisms

through their enzymes degrade (metabolize) the

organic contaminants from the soil or the water and

transform it into non-toxic end products, above all,

to carbon dioxide and water. In this process, there-

fore, occurs the interaction between plants and mi-

croorganisms, and the end result is a cleansing and

healing of the land. Bioremediation is a natural pro-

cess, which is to be carried out in soil and water and

without human influence, but it would last much

longer. The process is completely harmless to hu-

man health and, most importantly, there is no addi-

tional environmental pollution. Bioremediation

technology, creating optimal conditions for growth

of microorganisms and increase of their numbers,

support the detoxification of certain quantities of

contaminants.

In order to successfully carry out the process

of bioremediation, it is necessary to know the char-

acteristics of the contaminant, localities and micro-

organisms. From these parameters depends the run-

ning time of bioremediation, which can often reach

several years. Some readily biodegradable contami-

nants can be degraded in less than a year, while the

high molecular weight contaminants degrade signif-

icantly longer. The most important characteristics

of the contaminant which is necessary to determine

are the possibility of bio-degradation, solubility in

water, the coefficient of absorption of the land and

chemical reactivity.

Characterization and description of the site in-

clude the determination of the depth and the surface

distribution of the contaminant, the concentration of

the contaminant in the locality, soil type or class of

water with their properties (pH, organic matter con-

tent, the content of microelements’ and microele-

ments, etc.), Presence or absence of substances that

are toxic to microorganisms, the presence of other

electron acceptors, and so on. When the microor-

ganisms are concerned, it is necessary, first of all,

that they are active, i.e., to have the ability for bio-

degradation of contaminants and their populations

in the locality is large enough, in order to more ef-

ficiently decompose the contaminant.

Bioremediation researchers have come up

with a lot of information about the mechanisms of

bio-oxidation, the resulted products and the influ-

ence of reaction conditions before the bioremedia-

tion technology began to be applied commercially.

Microorganisms which are able to degrade a variety

of classes of compounds, and under aerobic and

under anaerobic conditions, were quite well-tested,

as well as their need for an appropriate pH, nutri-

ents, oxygen, temperature, redox potential and

moisture. Depending on the amount of the available

oxygen in the soil remediation can take place under

aerobic and anaerobic conditions.

Aerobic and anaerobic degrading of land.

Aerobic degradation is performed by aerobic micro-

organisms, and to it, in addition to oxygen a signifi-

cant effect has the presence of mineral salts, tem-

perature and pH. Aerobic microorganisms require

salts of nitrogen, phosphorus, potassium, magnesi-

um, iron, zinc and others. The largest growth of

bacteria and fungi oxidants hydrocarbons is ob-

served in the temperature range of 25 - 40 °C.

However microorganisms show great adaptability

in terms of growth, as well as the temperature. The

optimum pH for the biodegradation is between 7

3058

FIGURE 1

The biodegradation of benzene with bacteria

FIGURE 2

The biodegradation of naphthalene with bacteria

and 8.5. However, changing the acidity of environ-

ment may influence the dominant species of micro-

organisms and thus the conditions for microbial

degradation.

Degradation of oil decreases with increasing

sediment depth and anaerobic. The methyl group on

the ends of the molecule of an alkane and aromatics

(toluene, xylene) are subject to oxidation reactions,

where the first is formed alcohol, then aldehyde and

in the end the carboxylic acid. Microbiological deg-

radation of toluene may result in benzaldehyde and

benzoic acid. Alkyl group is subject to reactions of

subterminalne oxidation provide the ketone or hy-

droxy-derivative. Thus, from hexane is derived 2-

hydroxyhexane and 2-ketoheksan, etc. Alkanes are

subject to the reactions of dehydrogenation: from n-

heptane creating 1-heptene. Cycloalkanes are sub-

ject to oxidation reactions: may result in hydroxyla-

tion of cyclohexane to form cyclohexanol, may be

created-keto derivative to form a cyclohexanone

and can take place and the reaction of dehydrogena-

tion of cycloalkanes.

Aromatic compounds are subject to hydrox-

ylation reactions and formation of ketone. Hydrox-

ylation is nonspecific and sometimes leads to the

formation of a ketone or quinone. The most com-

mon product is dihidrodiol when the two OH

groups are introduced to two adjacent C-atoms.

From benzene may derive phenol and hydroqui-

none. Depending on the substrate and the micro-

organism can occur various products when opening

the aromatic rings. There may be opened only one,

several or all of the rings. In aerobic conditions by

opening the ring in the molecule is formed two car-

boxylic or on carboxylic and one hydroxyl groups.

Degradation of benzene bacteria begins forming

cis-dihydrodiols, followed by dehydrogenation to

catechol and then comes to the ring-opening.

Bacterial degradation of naphthalene is the

same as for benzene – first occurs deoxygenation

(cis-1,2-dihidrodiol) followed by dehydrogenation

(1,2-dihydroxynaphthalene), and finally comes to

the opening of the ring.

The use of micro-organisms (decontamination

process) as biodegradation agents is in constant

increasing due to the enormous biodiversity and

unrivalled catabolic potential. Degradation abilities

are conditioned by catabolic genes and enzymes. In

addition, microorganisms have different mecha-

nisms for adaptation to hydrophobic substrates such

as: modification of the cell membrane, production

of surface-active substances, or the use of an efflux

pump to decrease the concentration of the various

components of toxicity.

The system for the biodegradation in microor-

ganisms is organized in a way that the starting

compounds in a larger number of peripheral path-

ways to transform certain central by-products, such

as catechol, homogentisate or protocatechuate

which are converted to the intermediate cycle of

tricarboxylic acids.

3059

FIGURE 3

The main pathways for the aerobic degradation of PAH in bacteria and fungi

Anaerobic process takes place under the action

of anaerobic microorganisms and is so slow that its

importance is negligible. However, it was found

that anaerobic digestion can take effect after the oil

had previously been exposed to aerobic microor-

ganisms. Anaerobic decomposition of hydrocarbon

is possible in the deeper layers of oil, i.e., in the

depth of oil sites without air supply. Actuators of

anaerobic degradation are usually sulfate-reducing

bacteria. The reaction of sulphate under the influ-

ence of microorganisms represents oxidation - re-

duction process. Thereby the sulfates are reduced to

hydrogen sulfide and hydrocarbons are oxidised.

Under anaerobic conditions degradation pro-

cesses are more specific, for example, pure cultures

of bacteria can reward benzylsuccinate toluene, and

from kisil a metilbenzysuccinate. The aromatics can

lead to the reduction of double bonds, such as tests

with microbiological cultures showed a reduction of

one or more double bonds in the benzene ring under

anaerobic conditions: benzene can occur cyclohex-

ene, toluene from a 4-methylcyclohexanol.

Microbiological communities and design

processes. In order the removal of the contamina-

tion was effectively it is necessary to provide ade-

quate oil-oxidizing microorganisms in sufficiently

large numbers, as well as the optimal conditions for

their growth and development as sufficient quanti-

ties of nitrogen and phosphorus. The most com-

monly is applied autochthonous micro flora, which

is isolated from the soil and multiplied in bioreac-

tors. Apart from yeasts of the genera Candida (C.

lipolytica, C. tropicalis), Hansenula, Torulopsis,

Rhodotorula and fungi from the genera Aspergillus,

Penicillium, Fusarium, Trichoderma and other pri-

mary role in the biodegradation of petroleum hy-

drocarbons are bacteria, including species from the

genera Pseudomonas, Vibrio, Arthrobacter, Aer-

omonas, Acinetobacter, etc. [4].

Lack of catabolic pathway for biodegradation

of certain xenobiotic today goes beyond the tech-

niques of bioengineering, because biochemical

pathways can evolve. In this regard, the exchange

of genetic information Pseudomonas soya beans

that is able to degrade a wide range of chlorobenzo-

ate and chlorophenols. If it is carried out genetic

engineering of microorganisms is referred to as

process of Bioaugmentation [5]. Bioremediation

depends not only on the type and concentration of

pollution and present microbiological community,

but also of hydro geochemical soil characteristics.

3060

TABLE 1

Technology of Remediation [15]

The status of

technology

Status

of technology

Availability

Application

in combination

Pollutants

Remediation

time

Residue

Overall

expenses

VOC

SVOC

Fuel

Inorganic

substances

Biologic processes ex situ

Biologic processing of the polluted soil

†††

⃰

†††

††

†††

†

†††

Composting

†††

⃰

†††

††

†††

†

††

†††

Controlled biologic processing of the pollut-

ed soil

†††

⃰

†††

††

†††

†

††

†††

Biologic processing of the polluted soil in

slurry state

††

⃰

†††

††

†††

†

††

Physical and chemical processes ex situ

Chemical reduction/oxidation

†††

◊

††

†††

solid

††

Halogen removal

†

⃰

††

†††

††

†

□

gas

□

Halogen removal

††

⃰

††

†††

†

††††

†

Soil washing

††

◊

††

†††

††

Soil vapor extraction ex situ

†††

⃰

†††

††

†

††

†††

Solidification/stabilization

†††

⃰

†

††

†

†††

Solvent extraction

††

◊

††

†††

††

†

†††

†

Supercritical fluid oxidation

•

Supercritical fluid extraction

•

Thermal processes ex situ

High temperature thermal desorption

†††

◊

††

†††

††

†

†††

††

Low temperature thermal desorption

†††

◊

†††

††

†††

†

†††

Incineration

†††

⃰

††

†††

†

†††

†

Pyrolysis

†

⃰

††

†††

††

†

†††

†

Nitrification

††

⃰

††

†††

††

†

Technology (plasma)

•

□

⃰

†††

□

Biologic processes in situ

In situ biodegradation

†††

⃰

†††

†

††

In situ bioventing

†††

⃰

†††

†

††

†††

Natural attenuation

•

†††

⃰

†††

†

†††

Phytoremediation

Physical and chemical processes in situ

Creating cracks in the layers (Fracturing)

††

◊

††

•

†††

Soil flushing

†††

⃰

†††

††

†††

†

□

Soil Vapor Extraction - SVE (Vacuum ex-

traction)

†††

⃰

†††

††

†††

†

††

†††

In situ solidification/stabilization

†††

⃰

†

††

†

†††

Thermal processes in situ

Enhanced vacuum vapor extraction

††

⃰

††

†††

††

†

†††

††

Vitrification

†

⃰

††

†††

†

Legend: ®- completely developed technology, o- pilot facility level of developed technology, • - there is no data, † - unsatis-

factory, †† - average, ††† - satisfactory, * - self-applied technology, ◊ - technology is applied in combination with other sub-

sequent technologies, □ - inadequate data, voc - evaporative organic compounds, svoc, semi-evaporative organic compounds

When designing bioremediation process must

prevent the further pollution spreads due to penetra-

tion in the ground water. Which variant of the

cleaning will be applied depends on the type of

contamination, the nature of the terrain, etc. It can

be applied technical, spontaneous bioremediation, a

combination of both, or a mixture of bioremediation

with non-biological treatment. As the usual concen-

tration of pollution in groundwater is less than in

the zone of pollution sources, then can be applied

different procedures for the original zone and the

widespread stain. Factors affecting the design of

bioremediation process are: the objectives to be

achieved in the treatment of land, spread of pollu-

tion (type, concentration and location), type of bio-

logical process that efficiently transforms pollution,

transport dynamics of the land.

RESULTS AND DISCUSION

Types of soil remediation. Bioremediation

can be divided into two basic types:

a) Passive bioremediation, which applies

when the natural conditions are suitable for taking

place of bioremediation without human interven-

tion; b) Technical (engineered) bioremediation,

which is applied when it is necessary to add sub-

stances that stimulate microorganisms.

Passive Bioremediation involves the reduction

of the concentration of pollution by natural pro-

cesses. Passive Bioremediation is applied when the

natural biodegradation degree of pollution is faster

than the degree of migration of pollution. This rela-

3061

tive ratio depends on the type and concentration of

pollution, microbial communities and hydro geo-

chemical characteristics of the soil. It is mainly

used to clean the aquifer where the source of pollu-

tion has been removed, although it can also be used

when the source is still present or if there are re-

moved some dangerous points.

Natural removal of contamination may be due

to the destructive (aerobic and anaerobic biodegra-

dation, abiotic oxidation, hydrolysis) and non-

destructive (sorption, dilution (dispersion and infil-

tration), volatilization) process. Advantages of nat-

ural removal are the lower cleaning costs and min-

imal disruption of the landscape. Disadvantages

include the inability to remove high concentrations

of pollution, it may cause migration of pollution,

time degradation of severe fraction is long, cannot

always achieve the target value for the concentra-

tion of pollution for a reasonable time, the condi-

tions on the site may be unfavorable, you need a

long-term monitoring. In order the passive biore-

mediation was favored the following conditions are

required: a steady flow of groundwater, the pres-

ence of minerals that protect to prevent changes in

pH environment, the presence of high concentra-

tions of oxygen, nitrate, and sulfate, iron (III). Pas-

sive bioremediation relies on the natural abilities of

the present microbial communities.

The ability of natural microorganisms to per-

form passive bioremediation must be proven by

laboratory tests conducted on specific land. These

tests must be carried out before the establishment of

passive bioremediation that would be accepted as a

legitimate technique for cleaning. In addition, the

efficiency of passive bioremediation must be prov-

en by field monitoring that includes chemical anal-

ysis of pollution, the final electron-donor and/or

other reactants or products characteristic of the bio-

degradation process.

Passive bioremediation can be used alone or in

conjunction with other remediation techniques.

Similarly, this process can be applied after the

"pump it-and-treat" technique or after a technical

bioremediation to prevent migration of pollution

from a given locality. Primarily, in the application

of passive bioremediation is that the land must be

fully tested. The parameters that need to pay atten-

tion are: type, quantity and distribution of pollution,

contamination susceptibility to biodegradation by

microorganisms in the soil, groundwater flow when

pumping is not performed (including seasonal fluc-

tuations), the period of migration stains and intima-

cy and sensitivity of potential receptors, which can

be harmfully favored if they come into contact with

the pollution. If our information on all of these pa-

rameters is available, we can use a mathematical

model to determine the relationship of migration

and biodegradation.

Key characteristics of the land suitable for

spontaneous bioremediation are: a steady flow of

groundwater (speed and direction) through the sea-

son: - seasonal variations in the thickness of water

table <1m, seasonal variations in regional trajectory

of the flow fulfilled the expectation. If expectations

are not met and pollution is spreading, must contin-

ue to apply further corrective measures.

Other technical terms for bioremediation are

"enhanced" bioremediation and "biorestoration".

Technical bioremediation is faster than passive,

because it’s carried out the stimulation of microbio-

logical degradation of the pollution through the

control of concentrations of oxygen, nutrients,

moisture, content, pH, temperature, etc. Technical

bioremediation is applied when it is important that

cleaning is carried out for a short time or when the

stain is rapidly expanding. Its application reduces

costs due to shorter treatment and fewer land sam-

ples and analysis, and it is important for political

and psychological needs because the community is

highly exposed to contamination. It is subject to

variations due to geological, hydrological and

chemical characteristics of the soil and the neces-

sary biochemical process, and an important aspect

when establishing the technical bioremediation is

whether is treated the land or water.

In situ and ex situ bioremediation. Depend-

ing on the execution site of decontamination, bio-

remediation technologies are divided into two sub-

categories: in situ and ex situ. In situ bio-

technologies are carried out directly on the site of

contamination, while the ex situ bio-technologies

the contaminated soil is removed from the site of

contamination and transported to the "pro-

cessing/treatment." locality. In situ bioremediation

technologies are substantially more cost-effective

than ex situ technologies, because they allow the

treatment of contaminated soil directly to the site of

contamination, while avoiding the costs of excava-

tion and transportation.

In situ bioremediation technologies are very

effective when subsurface soil is very permeable,

when includes land located in the depths of a max-

imum of 8 - 10 meters and when groundwater is

present at depths below 10 meters. The depth of the

contamination is a very important factor that deter-

mines whether the in situ bioremediation will be

applied. In the case that the contaminations are

penetrated to the proximity of groundwater, it is

necessary the excavation of contaminated soil, or

applied ex situ bioremediation technology in order

to avoid contamination of groundwater. The perme-

ability of the land also has great significance. Land

with low permeability is not suitable for in situ bio-

remediation. In case that in situ bioremediation

technologies applied without additional aeration,

the effective diffusion of oxygen, which would en-

able a satisfactory level of bioremediation can be

achieved for the majority of land in the depths of a

few to thirty centimetres. Some of the most im-

3062

portant in situ bioremediation technologies are su-

perficial landfarming, bioventilation, biorasplasing,

biostimulation and phytoremediation.

In situ Bioremediation is based on the treat-

ment of contaminated soil or water at the same lo-

cation where it is detected for the presence of con-

taminants. The main goal of aerobic in situ biore-

mediation is to provide oxygen and nutrients neces-

sary for the growth of microorganisms in order to

effectively degradation of contaminants. This group

of methods, among others, involves the bioventila-

tion and insertion of hydrogen-peroxide. In the sys-

tem of bioventilation air from the atmosphere is

injected into the contaminated soil or water, and

oxygen, which in this way reaches to the system,

uses the microorganisms for own biosynthesis, as

well as the degradation of contaminants. By inject-

ing hydrogen peroxide and its circulation through

the contaminated soil, provides the oxygen stimu-

lating effect on microorganisms, which, through its

activities, contribute to the degradation of contami-

nants.

Ex situ bioremediation techniques are faster,

easier to control and allow the decomposition of a

wider spectrum of contaminants than in-situ biore-

mediation. These techniques involve the excavation

and treatment of contaminated soil before, and

sometimes, after performing of bioremediation. The

most common method of ex situ bioremediation is

mixing of contaminated soil with appropriate

amounts of water in a special 'bioreactor' with the

addition of microorganisms. Information in the

field of molecular ecology can be useful for the

development of bioremediation method and evalua-

tion of environmental impact. These information’s

have special application in the process of bioaug-

mentation or the introduction of exogenous micro-

organisms in contaminated soil or groundwater.

The nature of soil pollution. Some types of

microorganisms can use oil as a carbon source, a

kind of oil kills or inhibits, while some species are

not affected. Physical and chemical characteristics

of oil affect the degree and speed of its degradation.

Physical effects of importance to biodegradability

are: viscosity, photolytic activity, evaporation, me-

chanical dispersion, dissolution, bioemulsification

and sorption. Viscosity affects the spread of oil

slicks, and thus an increase in the surface suitable

for microbial attack, which tend to focus on the

interface of the oil - water. Low viscosity oil spilled

in the cooler temperatures is more resistant to bio-

degradation. Photolytic products are more polar and

therefore more susceptible to the biodegradation of

the compounds from which they arise. Liquid hy-

drocarbons are susceptible to biodegradation than

those in solid form.

As a special factor influencing the biodegrada-

tion can be considered concentrations of the indi-

vidual components in the oil. Certain compounds in

high concentrations, like phenol, m- and p-cresol,

can be degraded due to their toxicity, while at low

concentrations subject to the biodegradation. As it

regards the chemical composition of the oil, n-

alkanes are degraded faster than the other groups of

the compound. Also alkanes of medium chain

length are less toxic and decompose quickly from

n-alkane chain of large length (in excess of 30 car-

bon atoms) or a cycloalkane. Degradation of al-

kanes inhibits their ramifications, especially at low

temperatures.

Volatile compounds, benzene, toluene, ethyl

benzene and xylenes (BTEX), relatively easily are

degraded due to several factors: they are relatively

soluble in water, can serve as the primary electron

donor for many bacteria, they are quickly destroyed

and decomposed by bacteria which degrade BTEX

grow rapidly in the presence of oxygen. The PAHs

are slowly degraded due to the complex structure,

low solubility and strong alveolar features. The

half-life degradation of PAHs low molecular mass

(naphthalene, alkyl naphthalene) takes few days in

the atmosphere, week in the water, months in the

soil and about a year in sediment. The PAHs of

higher molecular mass, with five or six-membered

condensed rings in the molecule are more stable,

with a half-life of several weeks to several years.

The efficiency of biodegradation of individual

PAHs in sediment decreases with the number of

condensed rings in the molecule, so that the five-

member and six-member PAHs are very difficult to

to get degraded.

The factors affecting the efficiency of bio-

remediation. The success of the bioremediation

process apart from microorganism capability to

degrade contaminant as a carbon source must be

taken into account other factors such as easily

adoptable source of nitrogen and phosphorus (nutri-

ents), humidity, temperature, oxygen (aeration) and

the presence of surfactants. In addition, important

are the characteristics of the soils, such as pH, min-

eralogical composition and the content of organic

substances.

Polluting substances represents a carbon

source for microorganisms, and mainly contaminat-

ed soil is poor in nitrogen and phosphorus. The

inclusion of these components leads to increased

growth of microorganisms and accelerates the deg-

radation of contaminants. It is customary to add

nutrients to the soil in order to establish the mass

ratio of carbon: nitrogen: phosphorus (C: N: P) 120:

10: 1, which is about the relationship of these ele-

ments in the biomass. Addition of nutrients is re-

ferred to as bio stimulation, and can be used miner-

al fertilizer or organic fertilizer (manure, activated

sludge). The optimum soil moisture for bioremedia-

tion process is 12-30% or 40-80% saturation capac-

ity. Insufficient humidity limits and reduces the

3063

growth of microorganisms and reduces excessive

humidity of aerating soil.

Temperature affects the microbial growth, the

composition of microbial communities and the rate

of degradation of pollutants. In addition, since the

temperature depends on the viscosity, solubility,

physical nature and chemical composition of petro-

leum pollutants. Biodegradation of hydrocarbons

can be carried out in a wide temperature range. Iso-

lated are the psychrophilic mesophilic and thermo-

philes microorganisms that use hydrocarbon oil as

the sole source of electrons and atoms [4].

The degradation of petroleum pollutants is the

fastest and most complete exercised under aerobic

conditions. The availability of oxygen depends on

the intensity of the total microbial consumption and

soil types. In order to increase the concentration of

oxygen in the contaminated environment using a

number of methods, such as rolling over, forced

aeration, by mechanical mixing, bioventilation, the

introduction of air and addition of alternative

sources of oxygen such as hydrogen peroxide or,

preferably, magnesium peroxide.

pH soil determines the type of bacteria that is

available for biodegradation. Most bacteria corre-

spond to a neutral pH, and mushrooms slightly acid

environments. Usually is the optimum pH for bio-

remediation in the range of 6 to 8. If the soil is acid-

ic, lime is added, and if it is too alkaline pH is ad-

justed by adding ammonium sulphate.

Surfactants are compounds that reduce the sur-

face tension of the water and increase the solubility

of hydrophobic substances in water. Hydrocarbons

bind to the particles of soil, surfactants and soil in

the pores of aiding the process of desorption of the

non-polar compounds from the soil particles, there-

by increasing their bio-adaptability. May be used

surfactants both from chemical and biological

origin. Chemical of surfactants used in the biore-

mediation must be biodegradable and that do not

inhibit the growth of micro-organisms. Some mi-

cro-organisms synthesize biosurfactants glycolipids

such as rhamnolipids in strains of Pseudomonas

aeruginosa or trehalose ripids in the genus of Rho-

dococcus, lipopeptides such as surfactant in in the

genus of strains of Bacillus subtilis, the polymers as

emulsion in bacteria Acinetobacter calcoaceticus.

Although it was confirmed that the biosurfactants

are formed and in the soil, is generally considered

to be in situ bioremediation is not achieved in an

effective concentration of surfactant. As an alterna-

tive there is the process where rhamnolipids prod-

ucts in a separate proceeding, and then added to the

plant for bioremediation [10-15].

The texture of the soil affects the permeability,

the moisture content and the total density of the

soil. Finely splashed soils are less permeable than

land with large particles. Soils with low permeabil-

ity are usually plastered and impede the distribution

and transport of moisture, nutrients and air. To such

land during the bioremediation can be added agents

such as straw or sawdust to achieve the desired tex-

ture. The speed and degree of degradation also af-

fects the type of contaminated soil, clay content and

organic substances, and the stake of individual frac-

tions of sand. Land which includes sand and gravel

in the overwhelming amount has good drainage

capacity, i.e., very shortly retains water and is per-

meable to air.

CONCLUSION

The market of remediation technology is con-

stantly increasing. Although the share biological

methods on the market, about 10%, bioremediation

has significant advantages as compared to other

technologies in terms of cost and efficiency in the

removal of the pollutants. This technology infringes

at least the environment, particularly in the applica-

tion of in situ, and is convenient to strategy of sus-

tainable development. However, bioremediation is

not universal and is not applicable to all pollutions.

The effectiveness of bioremediation of land de-

pends on a number of parameters: environmental

factors, additive and availability of nutrients and the

technical characteristics of the plant. It is important

to point out that even under optimal conditions, the

process does not remove all the contaminants, but

the effectiveness and cost-effectiveness of the bio-

logical process depends on the identification of

critical factors and their optimization.

In the countries of the Western Balkans are yet

to develop remediation technologies, and in a world

where bioremediation is already commercially used

on an industrial scale for more than 10 years con-

stantly improve techniques to expand the list of

contaminants that treatment can be applied, and the

process is accelerated with the aim of increasing

efficiency. They study the metabolic pathways and

the role of certain strains of the microbial commu-

nities. The ecotoxicological methods are introduced

for monitoring and evaluation of current processes,

studying the distribution of contaminants before

and after the applied treatment. Of particular im-

portance are strategies to increase the bioavailabil-

ity of contaminants, as well as introducing biologi-

cal steps in processes based on chemical or physical

methods [16-22].

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Received: 13.4.2018

Accepted: 28.02.2019

CORRESPONDING AUTHOR

Sonja Ketin

Faculty of Maritime Academic Studies Belgrade

Belgrade 11000 – Serbia

e-mail: ketin.sonja@gmail.com

Perspectives on the microorganism of extreme environments and their applications

Article

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Apr 2022

Extremophiles are organisms that can survive and thrive in conditions termed as “extreme” by human beings. Conventional methods cannot be applied under extreme conditions like temperature and pH fluctuations, high salinity, etc. for a variety of reasons. Extremophiles can function and are adapted to thrive in these environments and are sustainable, cheaper, and efficient, therefore, they serve as better alternatives to the traditional methods. They adapt to these environments with biochemical and physiological changes and produce products like extremolytes, extremozymes, biosurfactants, etc, which are found to be useful in a wide range of industries like sustainable agriculture, food, cosmetics, and pharmaceuticals. These products also play a crucial role in bioremediation, production of biofuels, biorefinery, and astrobiology. This review paper comprehensively lists out the current applications of extremophiles and their products in various industries and explores the prospects of the same. They help us understand the underlying basis of biological mechanisms exploring the boundaries of life and thus help us understand the origin and evolution of life on Earth. This helps us in the research for extra-terrestrial life and space exploration. The structure and biochemical properties of extremophiles along with any possible long-term effects of their applications need to be investigated further.

A survey on constructed wetland publications in the past three decades

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Jul 2023
ENVIRON MONIT ASSESS

Decentralised wastewater treatment systems, such as constructed wetlands, are becoming increasingly popular these days because they are more economical and cost-effective than conventional plants. The primary objective of this review paper is to determine the number of studies that have been conducted on constructed wetlands, specifically ‘free water surface flow constructed wetlands’, ‘horizontal subsurface flow constructed wetlands’, ‘vertical subsurface flow constructed wetlands’, and ‘hybrid constructed wetlands’. In addition, the paper examines the status of research publications on constructed wetlands by country, author, and journal. Based on the review, it has been found that although constructed wetland technology is economical and cost-effective, it is still not among the top 10 effluent treatment methods. Compared to other constructed wetland systems, ‘hybrid constructed wetlands’ have received minimal attention. Based on the search results, 4639 documents published between 1989 and 2021 have been extracted from the online edition of SCI-EXPANDED, Web of Science. The documents associated with constructed wetlands are divided into eight main document types. Articles and proceedings papers are the most common document type, accounting for 93% of all publications, followed by reviews (4%), meeting abstracts (1.3%), corrections (0.56%), editorial materials (0.38%), news items (0.2%), letters (0.04%), and book reviews (0.02%).

Comparison of 2- and 3-Compartment Electrodialytic Remediation Cells for Oil Polluted Soil from Northwest Russia

Article

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Apr 2020

Electrodialytic remediation is a method based on electrokinetics, in which an electric field of low intensity increases the availability of pollutants in solid waste materials. The electric field induces processes that mobilize and transport inorganic and organic pollutants. The transport of ions in the electrodialytic cell is controlled by employing ion-exchange membranes, allowing separation of the electrodes from the solids. In this study, using a two cell design, electrodialytic experiments were conducted to compare remediation of a heavily oil-polluted soil from Arkhangelsk, Russia. The 2-compartment cell has not previously been employed for electrodialytic removal of organic pollutants and was tested along with the traditional 3-compartment design. The influence of experimental variables (current density, remediation time, stirring and light) and settings on the two cell designs was investigated. The highest removal (77%) of total hydrocarbons (THC) was observed in the 3-compartment cell at high current density (0.68 mA/cm²), longer remediation time (28 days), stirring and exposure to daylight. High current density and stirring increased the removal efficiencies in both cell designs. Within the studied experimental domain, the removal efficiencies in the 3-compartment cell (10-77%) were however, higher than those observed in the 2-compartment cell (0-38%).

EMERGING TRENDS OF EXTREMOZYMES IN INDUSTRIAL BIOTECHNOLOGY

Chapter

Mar 2024

Biotechnology is one of the emerging fields that can add new and better application in a wide range of sectors like health care, service sector, agriculture, and processing industry to name some. This book will provide an excellent opportunity to focus on recent developments in the frontier areas of Biotechnology and establish new collaborations in these areas. The book will highlight multidisciplinary perspectives to interested biotechnologists, microbiologists, pharmaceutical experts, bioprocess engineers, agronomists, medical professionals, sustainability researchers and academicians. This technical publication will provide a platform for potential knowledge exhibition on recent trends, theories and practices in the field of Biotechnology

MENADŽMENT BIOREMEDIJACIJE I BIOHEMIJSKIMETABOLIZAM U "ZELENOJ HEMIJI"

Conference Paper

Full-text available

Jun 2023

U uslovima hemijske kontaminacije zemljišta i vode, enzimski metabolizam kao bio-hemijski process, sve više se koristi u modifikaciji hemijskih jedinjenja u živim organizmima i ćelijama. Metabolizam se deli na anabolizam odnosno biosintezu (stvaranje) kompleksnih organskih molekula i na katabolizam, koji je obrnuti proces od anabolizma, a to je razdvajanje kompleksnih organskih jedinjenja u jednostavnija jedinjenja. Bioremedijacija je u suštini proces koji predstavlja sposobnost mikroorganizama da razlažu različite opasne materije, i ima rastuću ključnu ulogu u prečišćavanju zagađenog zemljišta i podzemnih voda. Bioremedijacija je ekonomski isplativa, zelena tehnologija kojom se zagađujuće supstance biološkim putem transformišu u netoksična jedinjenja ili se potpuno razgrađuju do ugljendioksida i vode. Kao biološki agensi se najčešće koriste mikroorganizmi. Ovi procesi dobijaju svoje mesto zahvaljujući kapacitetu enzimskog metabolizma mikroorganizama da transformišu organske zagađivače u polutante i manje opasna jedinjenja. Ali, ne treba zaboraviti da ovu metodu nije moguće primeniti u svakom slučaju. Među raspoloživim opcijama za prečišćavanje zagađenog zemljišta, bioremedijacija je najbolja zato što najmanje remeti životnu sredinu i sa ekonomske tačke gledišta-manje košta. U ovom radu je dat i pregled ex situ bioremedijacionih postupaka na industrijskom nivou korišćenih za tretman kontaminiranog zemljišta.

Application of Microbial Enzymes in Wastewater Treatment

Chapter

Jan 2023

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Chapter

Jan 2023

Recent years’ rapid industrialization has led to the creation of new or emerging pollutants (EPs) and their release into the environment, which are thought to pose potential risks to the environment and public health. New technologies are therefore needed to decontaminate these emerging contaminants from contaminated sites. The use of living organisms (plants and microbes) in bioremediation, which has shown great promise, is time-consuming and suffers when contaminants are high (causing toxicity to the microorganisms). Recent developments in nanotechnology and bioremediation have greatly increased the potential for efficient and sustainable decontamination methods. For instance, when combined with plants, nanozerovalent iron (nZVI) rapidly breaks down organic pollutants like chlorpyrifos and can accumulate broken-down by-products. Similar to this, enzyme-loaded nanomaterials could be used to break down resistant organic pollutants into simpler compounds through the combined efforts of microbes or plants. The bioremediation technologies for treating emerging contaminants are covered in this chapter. Additionally, it discusses the integration of nanotechnology with bioaugmentation and its potential benefits and drawbacks.

Bioremediation of Cucurbitacins from Cucurbitacin Phytonematicides

Chapter

Jun 2022

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Bioaugmentation as a strategy for the removal of emerging pollutants from wastewater

Chapter

Jan 2022

In recent years, rapid industrialization had led the occurrence of new or emerging pollutants (EPs) and their release to the environment that are considered to be as potential threats to environment and human health. Hence, there is a need for new technologies for decontamination of these newly emerging contaminants in contaminated sites. Biological methods such as bioremediation which involves living organisms (microbes and plants) have shown great potential, but require long time and also suffer when the contaminant level is high (causing toxicity to the microorganisms). In recent times, the advancement of nanotechnology and its integration with bioremediation provides immense potential for sustainable and effective decontamination technology. For instance, nano zerovalent iron (nZVI) rapidly degrade organic pollutants such as chlorpyrifos and coupled with plants can accumulate degraded products. Similarly, nanomaterials encapsulated enzymes might be used for the resistant organic pollutant degradation into simpler compounds due to joint activities of microbes or plants with the enzyme loaded in nanomaterial. This chapter discusses the integration of the use of nanotechnology with Bioaugmentation, its potential opportunities, and finally challenges associated with it.

Technology for the remediation of soil

Article

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Jan 2015

This paper presents the importance of soil remediation technology in large process systems (oil and petrochemical industry, electricity production). Various types of technology have been compared and presented with all their advantages and shortcomings. Some solutions for specific examples when the soil remediation is required are suggested. The examples are used to present all the problems and their solutions when a contaminated soil requires remediation. © 2015, National Centre for Agrarian Sciences. All rights reserved.

Chemical Processes of Decontamination in the Treatment of Hazardous Substances

Article

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Jan 2015
POL J ENVIRON STUD

When CB (chemical and biological) armor is applied as protection against CB accidents and CB terrorism and to remove the consequences of contamination, one of the principal activities is performing final decontamination. For this purpose, caporit (calcium hypochlorite) in water solution is, we believe, the most frequently used material. This is an inorganic substance with active chlorine. When solution is properly prepared, it is useful, economical, effective, and applicable for decontamination and desinfection activities. Production of this material consists of finding production materials, collecting them, proper equipment use, quantifying, preparing both the production area and the equipment, solution production, effectiveness control, and, finally, the use of product made. Technology depends on quality and quantity of repro material in disposal, aperature, and equipment, employees' education, business organization, and protective measures during the working process. In terms of highly-toxic chemical and biological contamination it is necessary to perform chemical and biological decontamination as soon as possible.

Method for comparison of the maximum range of chemical pollutants

Article

Full-text available

Jan 2015
RUSS J GEN CHEM+

This paper analyzes the oil and petrochemical complex with four scenarios (for different threshold limit values of pollutants concentrations) from whence the following conclusions have been made: Based on the results of modeling and analysis of aggregate data it can be concluded that the application of software ALOHA (model) it is possible to plan and manage the set limit values for concentrations of pollutants in industrial plants along with monitoring the dispersion of pollutants in the oil and petrochemical complex. The model was applied, which based on Gaussian distribution calculates maximum range of pollutants and pollutant concentrations. These researches are specific, highly complex and rare, and for the first time conducted by using the model of SO2 and NO2 dispersion, the dominant pollutants in the oil and petrochemical industry complex. The paper provides relevant information based on which emitters were detected with the highest level of environmental and working environment pollution. By the analysis of the used data conclusions were obtained about the effects of pollutants on pollution that provide safe and reliable conclusion on the emitters, causes of pollution of industrial plants of oil and petrochemical complex.

Bioremediation of soil polluted with crude oil and its derivatives: Microorganisms, degradation, pathways, technologies

Article

Full-text available

Oct 2011

The contamination of soil and water with petroleum and its products occurs due to accidental spills during exploitation, transport, processing, storing and use. In order to control the environmental risks caused by petroleum products a variety of techniques based on physical, chemical and biological methods have been used. Biological methods are considered to have a comparative advantage as cost effective and environmentally friendly technologies. Bioremediation, defined as the use of biological systems to destroy and reduce the concentrations of hazardous waste from contaminated sites, is an evolving technology for the removal and degradation of petroleum hydrocarbons as well as industrial solvents, phenols and pesticides. Microorganisms are the main bioremediation agents due to their diverse metabolic capacities. In order to enhance the rate of pollutant degradation the technology optimizes the conditions for the growth of microorganisms present in soil by aeration, nutrient addition and, if necessary, by adding separately prepared microbial cultures. The other factors that influence the efficiency of process are temperature, humidity, presence of surfactants, soil pH, mineral composition, content of organic substance of soil as well as type and concentration of contaminant. This paper presents a review of our ex situ bioremediation procedures successfully implemented on the industrial level. This technology was used for treatment of soils contaminated by crude oil and its derivatives originated from refinery as well as soils polluted with oil fuel and transformer oil.

Microecological effect of cyfluthrin-degrader, strain FLQ-11-1, simulating bioremediation in situ

Article

Jan 2016

The influence of cyfluthrin-degrader, a novel Lysinibacillus sphaericus strain, FLQ-11-1, with respect to biodegradation effectiveness and its effects on soil microbial community simulating in situ, was evaluated. Two 4-kg soil samples containing 100 mg/L of cyfluthrin were set up, one without cyfluthrin degrader inoculation and one inoculated with degrader. The results showed that the cyfluthrin concentration in the inoculated soil declined by 99.45% within 28 days, whereas in strain-free samples, this concentration decreased by 29.1%. The amount of culturable bacteria in the inoculated soil grew faster in the 7 days after inoculation than in the strain-free sample, although it was low in both samples. PLFA profiles of soil after inoculating strain FLQ-11-1 displayed significant difference, with the character of biomark 18:0 negative related to cyfluthrin residue content. microrganisms L. sphaericus and P. amygdali, were only detected in the the soil inoculated with FLQ-11-1, while R. leguminosarum and Nitrosospira sp., were special microbes in the free soil, and twelve bacterium were in common. And strain FLQ-11-1 were the advantage organism in the 28 day, accomplying with the microbial diversity recovery. These results showed that strain FLQ-11-1 could well colonized in the cyfluthrin-polluted soil, although change the indigenous microorganism community diversity in its earlier bioremediation action, but contribute to recover the indigenous microorganisms community with decreasing of cyfluthrin in the soil.

Isolation and characterization of alkali-tolerant crude oil degrading bacteria consortia from the oily sludge

Article

Dec 2017

This study details the indigenous oil-degrading consortia, using crude oil as sole carbon and energy sources, which were screened out from the oily sludge of Central-Asia arid region via a crude oil mineral salt medium (MSM) plate tests. The enriched consortia are considered as heterotrophic alkali-tolerant microorganisms, which readily grew under the pH 6.0-12.0. Moreover, petroleum hydrocarbon degradation in water exhibited that the decomposition rate was the highest at pH 11.0 and reached 68.57% for the 8 d period. For the alkaline oily sludge with pH of ∼10, the selected consortia could consume 60% of petroleum hydrocarbon in 7 days of aerobic cultivation, indicating that it had the potential practical application in remediation of crude oil-contaminated saline-alkaline soil and sludge. GC-MS analysis of the residual hydrocarbons showed that chain saturated alkane (C8 to C20) was greater than 90% treated for 8 days. Based on 16S rRNA gene sequences, the consortia were identified as Porphyrobactercryptus, Staphylococcus epidermidis, and Pseudomonas aeruginosa. Overall, the obtained oil-degrading strain presented a short growth period, the ease of isolation and screening, as well as the high crude oil degradation capacity and alkali-tolerant property, which would endow it to degrade crude-oil under alkali-wastewater or sludge.

Innovative soil-remediation technology for industrial site

Article

Oct 2001

H. Suzuki

A discussion of major tendencies in polluted soil treatment techniques covers soil pollution sources; in-situ and ex-situ treatment of polluted soil; on-site and off-site ex-situ soil treatment; merits and disadvantages of major soil remediation techniques, including high-temperature incineration, bio-remediation, chemical decomposition, solvent extraction of crude oil and PCB, and thermal desorption; recent examples of real cases, including samples taking by rotary boring and geo-probing, soil treatment plans and measures, and soil treatment equipment; and characteristics of solvent extraction technology developed in the USA by Terra-Kleen Response Group Inc.

Isolation and characterization of a diesel oil degrading bacterial strain from oil polluted soil of Pars special economic energy zone (Assalouyeh, Iran)

Article

Jan 2015

Diesel, a refinery product of crude oil constitutes is a major source of pollution in our environment. In the present study six different bacteria were isolated and identified from the soil around Pars special economic energy zone (Assalouyeh, Iran). The isolate with higher growth was identified as Pseudomonas aeruginosa strain RK64 based on 16S rDNA gene sequence analysis. The optimum pH that supported growth of strain RK64 was between pH 7.0 to 8.0. The strain exhibited maximum growth between 30 and 40 degrees C. The maximum growth was observed in 6% concentration of diesel and potassium nitrate caused the highest growth of isolates on diesel compared to other nitrogen sources. The strain also showed high cell surface hydrophobicity and emulsification index over a period of 7 days and surface tension was obtained 33.3 +/- 0.5 mN/m. GC-MS analysis showed that 99.5% of the diesel oil was degraded by the strain after one week of incubation. The current research showed high potential of P. aeruginosa RK64 in biostufactant production and diesel oil degradation.

A comparative assessment on soil environment quality of Anhui Province (China) based on chemical analyses of Heavy Metals

Article

Jan 2015

Contamination of soil by heavy metals is an increasing environmental issue. This paper reports the concentration of 11 metals in the soils sampled during 1991 and 2011 from 17 cities of Anhui Province (China). Among the detected metals, the concentration of Mn is the highest and Hg the lowest. In the past 20 years, the concentrations of soil Cd, Co, Mn and Cu demonstrated an increasing trend. In 2009, only Tongling City had a total metal concentration over 1,000 mg/kg, but in 2011, the eligible cities also included Bengbu, Chizhou, Fuyang, Huainan, Huangshan and Maanshan. Four assessment methods (two pollution indexes and two fuzzy mathematical models) were employed to investigate the soil environment quality of the 17 cities. Soil environment quality of most of the 17 cities were class I according to the comprehensive index model. In comparison with the single-factor index method, the comprehensive index model concerned both dominant parameter and average contribution of all factors to the integrated environmental quality. Using the two fuzzy mathematical methods (single-factor deciding and weighted average models), the environmental risks were determined to be class I or class II. However, divergence of the membership degree to each pollution class still occurred between the two methods. In fuzzy mathematical methods, membership functions were used to describe the limits between different pollution degrees, and different weights were allocated for the factors according to pollution contribution. Introduction of membership degree and weight of each factor to fuzzy mathematical models made the methods more reasonable in the field of environmental risk assessment.

Bioremediation of petroleum-contaminated saline soil using straw and starch wastewater as biostimulation agents

Article

Jan 2011

To evaluate the efficacy of straw and starch wastewater as biostimulation agents for the remediation of petroleumcontaminated saline soil, five remediation treatments with and without straw and starch wastewater were tested in laboratory. According to the total petroleum hydrocarbon (TPH) measurement and Sole carbon source utilization (BIOLOG) analysis, a large application of straw and starch wastewater could result in a satisfactory TPH biodegradation rate of up to 31.91 % and an overall increase in microorganism activity. In addition, denaturing gradient gel electrophoresis analysis of 16s rDNA genes indicated that the straw caused significant changes in community composition while the starch wastewater triggered a higher petroleum biodegradation rate by offering nutrients for biodegradation. Thus, in this study, an inexpensive bioremediation method was developed for petroleum-contaminated saline soil.

BIOREMEDIATION AND "GREEN CHEMISTRY"

Abstract

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