Recultivation principles of destructed silts
in oil pipeline construction
Исмаилов
Нариман Мамед оглы,
доктор биологических наук, профессор,
Сулейманов
Бахруз Аллахверди оглы,
кандидат физико-математических наук,
Панахова
Айтекин Акбер кызы,
аспирант.
Институт радиационных проблем
Национальной Академии Наук Азербайджана.
Ismailov
N. M.,
Suleymanov
B. A.,
Institute of Microbiology of Azerbaijan
National Academy of Sciences,
Panahova
A. A.,
Institute of Radiation Problems of
Azerbaijan National Academy of Sciences.
Introduction
Apparently,
the laying of the main pipeline of hundred kilometers in length is accompanied
by destruction of hundreds hectares of fertile soil. In case of pipelines lining
ground can and should be restored.
It
is important to restore silt at the main pipelines construction. While
developing rehabilitation projects there are defined the followings:
·
Borders of arable lands on a pipeline where
rehabilitation is necessary.
·
Thickness of a removed fertile layer on each part.
·
Width of a rehabilitation zone within the limits of a
strip of allotting.
·
Location dump for permanent storage of a removed
fertile layer.
·
Permissible destruction of the level fertile layer
above broken lands.
·
Removal, transportation and laying ways of a fertile
layer.
·
Scopes and methods of loading and export of a
superfluous mineral silt, and its unloading in specified places for the purpose
as well.
·
Methods of packing of the loosened mineral ground and
a fertile layer of ground after covering of the
pipeline.
Rational
rehabilitation of the lands during the construction of the main pipelines
allows the reducing scope of excavations, the saving biologically active silt layer
pollution and considerable reducing of soil and environment.
Basic
approaches used in remediation
According
to market testing remediation technology is developed on directions focused on purification
ground and reservoirs from the most various pollutants. In this connection
there are developed and used more than 27 types of technologies of environment purification
of a technical, physics- chemical and biotechnological orientation [1, 2, 3, 4].
Physical
and chemical methods differ from biotechnological ones with high standardization
result application technology, efficiency and predictability, but lose at the
expense of rigidity of influence on ground and the raised cost on 10-40 %.
Correspond
to the chemical methods of ground rehabilitation constitutes ground processing with
highly active adsorbents, such as lime treatment,
sulfate of sodium, ferric oxide, gypsing with
washing, adding organic and mineral fertilizers.
One
of the methods providing dispersion of oil pollution and improving contact with
microorganisms is surfactants adding. Washing substances wash mineral oil away from
silts together with water. The application combination of surfactants with
mineral fertilizers accelerates biodestruction.
Remediation or
bioremediation
Effectively
joint utilize of physic-chemical and biological methods are economical favour
at high levels pollution as well. Among physic- chemical methods from the ecology
point of view purification methods oil polluted ground in hydro cyclones is
most comprehensible at biologically decomposed surface-active substances
utilities. While effective solvents utilities oil of various mechanical structures
is wished away from ground the technology which provides safety of functional
activity of soil microbiotas and processing biodegradation of residual oil is
carried out. [3,11].
Addition
of oil decomposing microbial preparations, oil microflora (biota) directed activation
and long-term herbages seeding phytomelioration correspond to biological
methods as well.
Main principles of
bioremediation technologies.
Biotechnological methods supply microorganisms; application capable to
utilize various pollutants. The meaning of the term bioremediation: a
bio-life (Greek), remedio - to treat.
The
leading factor of self purification of oil polluted silts under natural conditions
is the biological factor. It’s based on the ability of microorganisms to
decompose a wide spectrum of organic compounds contained in polluted silts.
However under natural conditions self-purification process of silts from oil
hydrocarbons processes slowly and depends on aeration degree, oxygen availability,
nitrogen sources, phosphorus, etc.
Nowadays aerobic bacteria are mainly
utilized at the biopurification process. Researches showed their ability in
active hydrocarbons decomposition, demands according to existent as the most
effective for the growth were determined. Their metabolism has been
investigated in detail and it showed that products processed by microorganisms
of mineral oil products are not dangerous for a man and environment. The most utilized
biological preparations on the development of hydrocarbon oxidizing
microorganisms bacteria corresponding to Pseudomonas, Rhodococcus, Bacillus,
Arthrobacter, Acinetobacter, Azotobacter, Alkaligenes, Mycobacterium genera are
concerned; yeast Candida genus; threadlike actinomycetes of Streptomyces; the
fungus corresponding Aspergillus’s and Penicillium genera and other micromycetes.
Biostimulation in situ. This approach is based on stimulation of
natural (indigenous) growth of microorganisms contained in polluted soil and
potentially capable to utilize the pollutant, activity of which is suppressed because
of absence or lack of number of biogenic substrates - nitrogen, phosphorus,
potassium, etc. In this case by laboratory researches it is possible to determine
the following with the use of polluted soil samples; biogenic elements and
their quantity necessary for adding to the polluted soil to stimulate the growth
of the microorganisms, capable to decompose a pollutant. Many firms have been
patented bioadditives which have stimulating effect on a wide spectrum of the
microorganisms capable to utilities plenty of the pollutants [6, 8, 10].
Biostimulation in vitro differs for its sample biostimulation of
natural micro biota of polluted silt or water which is conducted at the start under
laboratory or industrial conditions (in bioreactors or in fermenter). Thus the
bioreactor primarily supplies selective growth of these microorganisms which
are most capable for effective pollutant utilization. Thus stimulated microorganisms
with necessary biogenic compounds increasing efficiency pollutant utilities are
added simultaneously as well [11].
Bioaugmentation («bioimprovement»). In this
case enriched with a plenty of the specialized microorganisms added to the
polluted soil selected beforehand from various polluted sources were
genetically modified. In the process of bioaugmentation alien microorganisms are
often added to the soil alien for it. After utilization of the pollutant the
quantity of viable alien microorganisms added to the soil from the outer mass
should be sharply decreased [7].
Below on the circuit there are shown the basic
stages of microorganisms’ selection - destructors from the polluted objects.
Microbial
screening and the analysis
Soil samples
|
↓
Definition of the number of oil oxidizing microorganisms
|
↓
Screening on various hydrocarbons
|
↓
Selection
|
↓
Identification
|
↓
Creation of microorganisms’ collection
|
↓
|
Creation of biological preparations
|
At
a method bioremediation choice - biostimulation in situ or in vitro one of the essential
parameters are those parameters of microbial system status of object. Such
parameters are number and biomass of microorganisms, correlations of
saprophytes and oil oxidizing microorganisms and direct correlation is detected
out among the number of populations of microorganisms and intensity of pollution,
otherwise it is absent.
Scales
can be used for a level rating of soil enrichment by microorganisms (tab. 1).
Tab. 1.
Scales for biostimulation methods of planning utilization depending on
enrichment an level of soil by microorganisms.
|
soil enrichment level |
Total number of
bacteria |
Dry bio-mass of bacteria |
Length of fungi |
Dry bio-mass of
fun-gi |
Number of bacteria
on Meat medium agar |
Number of bacteria
on Еshbi, Chapеcs and SAA (starch ammonium agar) |
Possible methods
of biostimulation ( in situ, in
vitro) |
||||
|
Mlyd/q |
Mlyd/ sm2 |
kq/ ha |
mq |
m/ sm2 |
kq/ ha |
mln/q |
mln/ sm2 |
mln/q |
mln/ sm2 |
||
|
Very pure |
1 |
50 |
42 |
30 |
750 |
120 |
1 |
25 |
1-2 |
50 |
in vitro |
|
pure |
1-2 |
50-100 |
42-85 |
30-100 |
750-2500 |
120-400 |
1-2 |
25-50 |
2-4 |
50-100 |
in vitro |
|
average |
2-5 |
100-200 |
85-170 |
100-300 |
2500-7500 |
400-1200 |
2-5 |
50-125 |
4-10 |
100-250 |
in situ |
|
Rich |
5-10 |
200-400 |
170-340 |
300-1000 |
7500-25000 |
1200-4000 |
5-10 |
125-250 |
10-20 |
250-500 |
in situ |
|
Very rich |
>10 |
>400 |
>340 |
>1000 |
>25000 |
>4000 |
>10 |
>250 |
>20 |
>500 |
in situ |
Cost of bioremediation
Nowadays
bioremediation methods are the most comprehensible from ecological and economic
points of view [5] (pic.1). Methods are used for purification of ground surface
on depth up to
Picture 1. Economic
purification profit oil polluted silts by different methods.
To
intensify process of decomposition of oil hydrocarbons (five and more times) is
possible by artificial adding to the soil the pure or mixed cultures of hydrocarbon
oxidizing microorganisms as biological products. Biological preparates made by
business concerns, represent a biomass of viable hydrocarbon cells oxidizing microorganisms
and differ in their reception application with especial physiology-biochemical properties,
Nowadays the market offers a big variety of biological preparation: Uni-Rem,
Petro, Petro trite, Avalon, Roder, Ekoil,
Fechel-bio, Devoroil, Econadin, etc.
The
utilization of genetically modified microorganisms for bioremediation can be
expedient when their biochemical characteristics providing bioremediation are
improved, and the spectrum decomposed pollutants is distributed, genetic
updating provides (or increases) the stability of microorganisms for the environmental
factors (stability on heavy metals, high concentration of salts, etc.), allows
to operate the vital functions of a microorganism and by that to supervise
their growth and activity.
References
1.
Velkov V.V. (1995). Bioremediation: principles,
problems, approaches. /Biotechnology, №3-4, p.20-27. (In Russian).
2.
3.
5.
Sinkova E.A. (2006). Rational ways to sanities of centers
pollution technogenic by hydrocarbon connections. // Sank-Petersburg, 25p, (In
Russian).
6.
Bayrai R.K., Zappi M.E., Gunnison D. (1994). // Annals
of the New York Academy of Sciences, v.721, p.450-465, (In
English).
7.
Bewley R.J.F. Release of Genetically Modified
Microorganisms –REGEM 2/Eds. D.E.S.Stewart Tull, M.Sussman.-N.Y and
8.
Bragg J.R., Pribce R.C., Harner E.J. ET all. (1994). //Nature,v.368,
N.6470, p.413-418, (In English).
9.
Funk S.B., Roberts D.J. and Crawford D.L. ET all.
(1993). // App. and Environmental Microbiology, v.59, №7, P.2171-2177, (In English).
10.
Mills S.A.,
Frankenberger W.T. (1994). //Bull. Of Environmental Contamination. And Toxicology,
v.53, N2, P.280-284, (In English).
11.
Shouche M.S.,
Petersen J.N., Skeen R.S. at all. (1994). //App. Biochemist and Biotechnology, v.45,
N6, p.775-785, (In English).
Поступила в редакцию
15.10.2009 г.