Impact of Sulphate-Reducing Bacterioa on the Performance of Engeneering Material - Reza Javaherdashti, July 2011.pdf

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Impact of sulphate-reducing bacteria on the
performance of engineering materials
Article in Applied Microbiology and Biotechnology · September 2011
DOI: 10.1007/s00253-011-3455-4 · Source: PubMed
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Impact of sulphate-reducing bacteria on
the performance of engineering materials
Reza Javaherdashti
Applied Microbiology and
Biotechnology
ISSN 0175-7598
Volume 91
Number 6
Appl Microbiol Biotechnol (2011)
91:1507-1517
DOI 10.1007/s00253-011-3455-4
1 23
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Appl Microbiol Biotechnol (2011) 91:1507–1517
DOI 10.1007/s00253-011-3455-4
MINI-REVIEW
Impact of sulphate-reducing bacteria on the performance
of engineering materials
Reza Javaherdashti
Received: 6 May 2011 / Revised: 14 June 2011 / Accepted: 15 June 2011 / Published online: 24 July 2011
#
Springer-V
erlag 2011
Abstract
Microbiologically Influenced Corrosion (MIC)
is an electrochemical corrosion influenced by the
presence/action of biological agents such as, but not
limited to, bacteria. One of the key elements of MIC is
sulphate-reducing bacteria (SRB). There are still many
misunderstandings about these bacteria, their role in the
deterioration of engineering materials and their impor-
tance over other types of corrosion-related micro-/macro-
organisms. SRB do not require oxygen, yet they can be
found in oxygenated environments; they are capable of
tolerating a relative wide range of temperature, pH,
chloride concentration and pressure values. Not only can
SRB have deteriorating impact on engineering materials,
they are also capable of inducing harm to health and
agriculture. In this paper, after reviewing facts and
figures regarding ecological and economical impacts of
corrosion in general and MIC, in particular, the central
concept of MIC, that is, biofilm formation and its
deterioration mechanisms and the role of SRB in such
mechanisms are described. Also, the possible enhancing
role of SRB on stress corrosion cracking of steels and
the controversial concept of no relationship between the
number of SRB and corrosion rate are addressed and
reviewed.
Keywords
Corrosion . Microbiologically influenced
corrosion . Sulphate-reducing bacteria . Biofilm . Stress
corrosion cracking
Introduction
Corrosion and its thermodynamics
Corrosion can be defined in many ways. ISO 8044 standard
defines corrosion as
“Physicochemical
interaction (usually
of an electrochemical nature) between a metal and its
environment which results in changes in the properties of
the metal and which may often lead to impairment of the
function of the metal, the environment or the technical
system of which these form a part” (Mattson
1989).
The importance of ISO definition in relation to the topic of
this paper can be summarised in the following two points:
1.
Electrochemical corrosion is a physicochemical reac-
tion; therefore, whatever is contributing to that, from
high internal stresses caused by heat treatment to the
existence of biological species, will eventually result in
more enhanced corrosion characterised by higher
corrosion rates.
2.
Corrosion is not an isolated process that will take place
without affecting many factors, including the system in
which corrosion is taking place. In other words,
corrosion has the capacity of working on feedbacks.
This is an important issue especially when it comes to
the so-called microbial corrosion because it seems that
there is a feedback between electrochemical corrosion
and microbial corrosion in the sense that they can
exacerbate each other. This matter will be explained in
more details later.
Another important conclusion that, in addition to the
above two points can also be mentioned is that due to the
thermodynamical nature of corrosion, it is a natural process
that can never be stopped but controlled. In other words, in
practice, either the observed corrosion rates are too small to
R. Javaherdashti (*)
Qatar University,
P Box 2713, Doha, Qatar
.O.
e-mail: rezaj@qu.edu.qa
Author's personal copy
1508
Appl Microbiol Biotechnol (2011) 91:1507–1517
be measured or accepted as 0 corrosion rates. The measures
that in practice are collectively referred to as
“corrosion
management” to allow for controlling corrosion at large in
industries, at their best, can lower corrosion to rates too low
to be measured and too slow to cause significant cata-
strophic damage.
All the above conclusions will be later used to address
the severity of microbial corrosion and the role of sulphate-
reducing bacteria (SRB) in it.
Importance of corrosion
The importance of anything can be measured through its
economical and environmental damage. This is of course
enhanced by an overwhelming academic interest in know-
ing the matter for itself.
It will be quite logical to assess the importance of
corrosion from both economical and ecological points of
view. Economy-wise, insurance companies have paid out
more than US $91 billion in losses from weather-related
natural disasters in the 1990s (Worldwatch News Brief
1999),
whereas direct loss of corrosion in 1994 just in the
US industry was US $300 billion. The cost of corrosion has
been reported from many studies to be of the order of 4% of
the Gross National Product (GNP) of any industrialised
country (Heitz
1992).
More details of such losses have been
reviewed elsewhere (Javaherdashti
2000).
About the environmental impact of corrosion, the
following facts and figures are important:
&
Internationally, 1 ton of steel turns into rust every 90 s;
on the other hand, the energy required to make 1 ton of
steel is approximately equal to the energy an average
family consumes over 3 months (El-Meligi
2010).
All corrosion controlling methods are intrinsically not
environmentally friendly(Javaherdashti and Nikraz
2010);
therefore, the must for controlling corrosion is
in fact related to have an as much as possible small
quantity of corrosion that in turn will require as small
quantity of corrosion controlling measures a relatively
great deal of are, in essence chemical, as possible.
3.
In addition to the presence of micro-organisms, nutrients
and water must be also present to initiate MIC.
It is well documented that almost all engineering
materials are vulnerable to MIC (Javaherdashti
1999,
2007;
Critchley and Javaherdashti
2004;
Ribas Silva and
Pinheiro
2007;
Maruthamuthu et al.
2008)
In fact, many
studies (Tiller
1983a;
Kovach and Redmond
1997;
Neville
and Hodgkiess
1998;
Sathiyanarayanan et al.
2002;
Y
uan et
al.
2010)
suggest that even the most promising engineering
materials, stainless steels, are also prone to MIC.
While there are relatively a large number of
“culturable”
type of bacteria whose corrosion impacts are known (Lane
2005),
perhaps the central bacteria of interest in MIC has
been the one known as SRB. Before preceding more, we
want to also introduce a few lines regarding the importance
of MIC.
Importance of microbiologically influenced corrosion
MIC is believed to account for 20% of the damage caused
by corrosion (Flemming
1996).
On the basis of GNP annual
,
MIC-related industrial loss in Australia, for instance, is
estimated to be more than US $5 billion (Javaherdashti and
Raman Singh
2001).
Over the past half of century, costs
imposed by MIC have always been a matter of concern for
corrosion technologists; a 1954 estimate of MIC loss in
buried pipelines, for instance, puts a figure between 0.5 and
2.0 billion US dollars a year—a figure that can only have
increased since then (Singleton
1993).
It has been
suggested that (Maxwell et al.
2004)
overall loss to the oil
and gas industry could be over US $100 million per annum.
MIC has been estimated to be responsible for the 10% of
corrosion cases in the UK (de Romero et al.
2000).
MIC
has caused a lifetime reduction of flow lines in Western
Australia from the designed +20 years to less than 3 years
(Cord-Ruwisch
1996).
Also, microbial corrosion has been
addressed as one of the major causes of corrosion problems
of underground pipelines (Li et al.
2003).
&
Microbiologically influenced corrosion
All definitions for microbial corrosion, or as more
technically known, microbiologically influenced corrosion
(MIC) (Little and Wagner
1997;
Beech et al.
2000;
Li et al.
2001;
de Romero et al.
2004),
are common in at least three
following basic ideas (Javaherdashti
2008):
1.
MIC is an electrochemical process.
2.
Micro-organisms are capable of affecting the extent,
severity and course of corrosion.
Biofilm: the
“nursery”
for bacteria, including
but not limited to, sulphate-reducing bacteria
Perhaps, the key element of understanding how SRB can
contribute to corrosion will be understanding the concept of
“mixed
bacterial communities” or
“biofilms”.
A manifesta-
tion of biofilms can be seen as
“tubercles”
on the surface of
metallic surfaces, resulting in localised corrosion under
these venues. Figure
1
shows an example of such tubercles.
Studies on metallic surfaces such as stainless steel,
galvanized steel and copper has confirmed that over time,
SRB number on these surfaces increases (İlhan Sungur et

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