Calcite forming bacteria, isolation, biocement production and advantages

1. CALCITE FORMING BACTERIA
AND
BIOCEMENT PRODUCTION
By
Saajida Sultaana Mahusook

2. Calcite
A common rock forming mineral of calcium carbonate
(CaCO3), found primarily in limestone
Used in cement production
Calcite-forming bacteria
A bacterium that forms calcite in the presence of
calcium ions is known as calcite forming bacteria
(CFB).

3. Microorganisms react with
the (Ca2+) ions in the
environment
Secrete one or more metabolic
products such as CO32-
Precipitation of minerals
MICROBIALLY INDUCED CALCITE PRECIPITATION

4. Metabolic process involved
• Urea hydrolysis
• Denitrification
• Sulfate reduction
• Carbonic anhydrase type of calcite formation
Bacteria types:
B. megaterium, B. subtilis, , B. thuringiensis, D.
halophila, L. sphaericus CH5, Methylocystis parvum,
Aerobacter aerogenes, Myxococcus xanthus, Proteus
mirabilis, Pseudomonas denitrificans, Sporosarcina
ginsengisoli and Sporosarcina pasteurii.

5. • Developed by Dutch scientists Eric Schlangen and
Henk Jonkers
• Alternative to cement and chemical grouts
• Biocementation produce binding material based on
MICP mechanism
• based mainly on application of urease-producing
microorganisms together with urea and calcium ions
in a permeable soil

7. Urea urease ammonia + carbonate ions
The bacteria creates an alkaline environment (high ph)
Calcite precipitation the presence of calcite ions

8. • Using B4 medium
Isolation
• Gram staining
• X-ray diffractometer analysis
• Calcite forming mechanism determinationCharacterization
• Biocement production
Biocement

9. Patented method for biocement production

10. Binder • cement
Aggregate • sand
Biological
mortar
• Limestone
powder
• nutrient
• Bacterial paste
Components

11. • The bacteria remains dormant for even 200 years
without food or O2 .
• When a crack occurs, the bacteria are activated with
H2O and the bacteria feed on calcium sources.
• Production and accumulation of calcite in the crack
spaces

14. • It needs shorter time for production
• The in-situ process raw material of bio cement are produced at low
temperature
• The eco construction material consumes less energy and less CO2
emission
• It increases compressive strength of mortar by up to 38%.
• It can remediate cracks in building materials and monumental stones
and regain strength within 28 days.
• To make the process economical, microbial additives can be
prepared by growing bacterial cells using industrial byproducts such
as lactose mother liquor and corn steep liquor as nutrient sources.
• It enhances the durability of bricks by reducing their permeability
and increasing compressive strength.