Bioremediation


General description


Bioremediation is defined as the process whereby organic wastes are biologically degraded under controlled conditions to an innocuous state, or to levels below concentration limits established by regulatory authorities[1]
In this way Bioremediation is a technology that aims the treatment of contaminated material, specially the cleanup of hazardous chemicals in soil, by the usage of microorganism action. This offers the possibility to destroy or render harmless various contaminants using natural biological activity. As such, it uses relatively low-cost, low-technology techniques, which generally have a high public acceptance and can often be carried out in situ, it uses naturally occurring bacteria and fungi or plants to degrade or detoxify substances hazardous to human health and/or the environment. Contaminant compounds are transformed by living organisms through reactions that take place as a part of their metabolic processes
In this field the term ‘bioaugmentation’ [8] is also widespread; this is used to describe the addition of cultured microorganism, to a subsurface, that is capable of biodegrading or transforming specific groundwater/soil contaminants, usually in this approach organism are more specialized for degrading specific target contaminants.

Some essential factors in this technology are in the next table.

tabela1.jpg

Table adapted form http://www.pollutionissues.com/A-Bo/Bioremediation.html


Different types of Bioremediation and Applications

Different techniques can be employed in bioremediation, classically they are called In situ and Ex situ. (table 1, [2] ) [2]
In situ techniques are defined as those that are applied to soil and groundwater at the site with minimal disturbance. Ex situ techniques are those that are applied to soil and groundwater at the site which has been removed from the site via excavation (soil) or pumping (water). [2][3]

tabela2.jpg


History

The use and manipulation of microorganisms for treatment of municipal waste-water have been applied since ancient times. The Romans, for instance, built intricate networks of sewers as early as 600 B.C. in order to collect wastewater which underwent subsequent biological treatment.[4]
The techonology itself was reportedly invented by George M. Robinson who was assistant county petroleum engineer for Santa Maria, California.
Anyway the date that probably is a mark for the bioremediation beginning is the first commercial use of a bioremediation system which was in 1972 in Ambler, Pennsylvania (National Research Council 47) to clean up a Sun Oil pipeline spill.


Companies

Some of the main companies involved in this type of technology are listed below:

Regenesis (http://www.regenesis.com/)
Kanzanci (http://www.microbial-products.com/default.asp)
Adventus (http://www.adventusgroup.com/)
Solinst http://www.solinst.com/
RNAS http://www.rnasinc.com/


Advantages and Disadvantages


Advantages:- As it is a "natural process” is therefore supposed by the public in general as an acceptable waste treatment process.
- It usually does not produce toxic by-products, the residues for the treatment are usually include carbon dioxide, water, and cell biomass
- It is usually less expensive than other technologies.
-
Can often be carried out on site, often without causing a major disruption of normal activities. This also eliminates the need to transport quantities of waste off site and the potential threats to human health and the environment that can arise during transportation.


Disadvantages:


- More research is needed for locations with complex mixtures of contaminants.
- Clean up using bioremediation often takes longer than other actions (incineration).
- The process must be carefully monitored to ensure the effectiveness. [3]
- Bioremediation is limited to those compounds that are biodegradable. Not all compounds are susceptible to rapid and complete degradation. [6]- Biological processes are often highly specific. Important site factors required for success include the presence of metabolically capable microbial populations, suitable environmental growth conditions, and appropriate levels of nutrients and contaminants. [7]
- It is difficult to extrapolate from bench and pilot-scale studies to full-scale field operations.
- Contaminants may be present as solids, liquids, and gases.
- Regulatory uncertainty remains regarding acceptable performance criteria for bioremediation.



By Sandra D. Silva


References


[1] Department of environmental quality http://www.deq.state.mi.us/apcrats/toc_collapsible_2.shtml
[2] M. Vidali, Bioremediation. An overview, Dipartimento di Chimica Inorganica, Metallorganica, e Analitica, Università di Padova Via Loredan, 4 35128 Padova, Italy, Pure Appl. Chem., Vol. 73, No. 7, pp. 1163–1172, 2001.
[3] J.H. Langwaldt, J.A. Puhakka, On-site biological remediation of contaminated groundwater: a review, Institute of Water and Environmental Engineering, Tampere University of Technology, PO Box 541, FIN-33101 Tampere, Finland Environmental Pollution 107 (2000) 187±197
[4] R. Barry King, Gilbert M., Long Practical Enviromental Bioremediation , the field guid
[5] http://www.pollutionissues.com/A-Bo/Bioremediation.html
[6] Vijai Elango et al, Bioremediation of Hexachlorocyclohexane Isomers, Chlorinated Benzenes, and Chlorinated Ethenes in Soil and Fractured Dolomite, Department of Environmental Engineering and Earth Sciences, Bioremediation Journal, Volume 14, Issue 1 January 2010 , pages 10 – 27
[7] Kela P. Weber et al, Influence of the Microbial Community in the Treatment of Acidic Iron-Rich Water in Aerobic Wetland Mesocosms, Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario, Canada, Bioremediation Journal, Volume 14, Issue 1 January 2010 , pages 28 – 37
[8] Regenesis (http://www.regenesis.com/)


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