Transcript 02-31078061 Biocementation

31078061
BIO 301 Industrial Bioprocessing
and Bioremediation
Microbial Production of Biocement
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Introduction
 Author profile
 Thesis 1 summary
 Thesis 2 summary
 Comparison between Thesis 1 and 2
 Conclusion
 Reference
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Introduction
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Cementaion, precipitation of calcium carbonate, occurs
in the process of microbial actions or naturally, forming
natural rocks which are presence in the marine
,freshwater and soil environment. (Salwa.A.T,2008)
Biocement, a solid crystaline form of calcium carbonate,
could be obtained through the microbial urease activity
occuring in the calcium-rich environment. (Whiffin,V. S.
,2004).
Biocementation is defined as the sand consolidation
technology in which the carbonate, released from the
microbial hydrolysis of the urea, in the presence of
excess calcium ions and from calcite(CaCO3)precipitate.
(Salwa.A.T,2008)
Author Profile
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Hello everyone , I am Frankie. I’m doing my third year
studies here at Murdoch university , majoring in
Biomedical science and Biotechnology.
The reason I chose this topic was that I got inspired by
the breakthrough of science in biocementaion which
attracts the commercial values.
Microbial CaCO3 precipitation for
the production of Biocement
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This article focus on the biocementaion of the specific bacteria S.
pasteurii and aim to produce biocement through a low-cost processes.
(Whiffin,V. S. ,2004).
The binding strength of the precipitated calcium carbonate can be
increased by regulating the rate of carbonate formation by the
bacteria. (Whiffin,V. S. ,2004).
The enzyme urease produced by S. pasteurii is found to be functional
in temperatures up to at least 80 ‘C , tolerating urea concentration up
to 3M and calcium nitrate mixture up to 2 M. (Whiffin,V. S. ,2004).
It is possible to reuse the urease activity which is one of the cost
effective ways of producing biocement. (Whiffin,V. S. ,2004).
Tests have been made to prove that this strain of bacteria is suitable
for biocementation. For example, the ammonium concentration does
not have a huge impact on urease activity.
(Whiffin,V. S. ,2004).
High strength in-situ Biocementation of soil by
calcite precipitating locally isolated ureolytic
bacteria
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Conditions that promote the urease activity of S. pasteurii was studied and
can be found that this activity can be increased by increasing the
concentration of yeast extract and nickel ions in the growth medium.
(Salwa.A.T,2008)
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A term Biomineralisation was introduced and the growth and strength of
the calcite crystal were studied, and it was found that the stregth is
produced within the first 3 to 4 hours of the biocementation process.
(Salwa.A.T,2008)
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The bacterial attachment to the intersurfaces such as sand granules ,has
been studied and could be concluded that in 1m sand column, the bacterial
attachment was stronger if they were grown in calcium ion rich medium.
(Salwa.A.T,2008)
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It was recommended that biocementation process can be damaging to the
environment because the ammonium produced from the hydrolysis of urea
could be leaked to the groundwater and hence, the use of carbonsources
in biocementation process may reduce this impact to the environment.
(Salwa.A.T,2008)
Comparison between Thesis 1 and 2
Thesis 1 focus more on the industrial
point of view, finding a way to make
the biocementation as cheap and
practical as possible.
 In thesis 2, a more detailed study has
been made on parameters affecting
the in-situ biocementaion process.
 Both thesis were concerned about the
ammonium impact on the
environment.
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Conclusion
Urease activity is an important part of the
biocementation process and could be increased by
concentrating the yeast extract and nickel ions in
growth medium.
 The strength of the calcite were produced in the first 3
to 4 hours of biocemtation process and could be
increased by regulating carbonate formation rate.
 The reuse of urease enzyme could be very costsaving to
the industrialized biocemation.
 The waste management of the ammonium is required
since it is harmful to the environment.
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Reference
Al-Thawadi, Salwa (2008) High strength insitu biocementation of soil by calcite
precipitating locally isolated ureolytic bacteria.
PhD thesis, Murdoch University
 Whiffin,Victoria S. (2004) Microbial CaCO3
precipitation for the production of biocement.
PhD thesis, Murdoch University.
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