Recultivation principles of destructed silts in oil pipeline construction

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Recultivation principles of destructed silts in oil pipeline construction

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

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).

rehabilitation land pipeline environment

Tab. 1. Scales for biostimulation methods of planning utilization depending on enrichment an level of soil by microorganisms.

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 1 meter.

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. Ismaylov N.M. (1996). Ecological of biotechnology of clearing in the decision of a problem recultivation petrol polluted soils of Absheron. // Baku, 41p, (In Azeri).

3. Ismaylov N.M. (2007). Remediation of soils polluted by oil and drill of sludge. // Baku. Science, 158p, (In Azeri).

4. Purification of soil from oil products on Absheron peninsula with the use of bioremediation technology. (2004). (Grant N UNOO3785-AZ025), «Azecolab» company, Baku, 19p.

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 London: Plenum Press, p.33-46, 1992.

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).

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