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Keywords: Environmental protection, bacteria, MICP.
Brick is an important construction material from the ancient time itself, but even though after the modernization in the construction industry, there is a research gap in the development of eco-friendly brick. Brick industry is resource intensive and polluting, having significant social and environmental consequences. Bangladesh currently produces around 17 billion bricks per year, consuming around 45 million tons of fertile soil and the brick kilns burn approximately 3.5 million tons of coal and 1.9 million of wood causing severe air pollution. According to a study by Bangladesh University of Engineering and Technology, brick kilns contribute about 38% of the pollution around Dhaka. The brick kilns emit toxic fumes containing suspended particulate matters rich in carbon particles and high concentration of carbon monoxides and oxides of Sulphur. Human and plant health is adversely affected by this and emission of huge quantity of toxic elements is resulting in a permanent change in the global climate. Realizing the treats from the years-old process of manufacturing brick, adapting an environment friendly process has become an important issue.
This article speaks about the brick making in using microbial bacteria, which could be a green solution for our current situation. The idea is the brain child of Ginger Doiser, an assistant professor at American University of Sharjah in the United Arab Emirates. The bricks are made in a process called microbial-induced calcite precipitation or MICP. In the whole process some local sand, bacteria and urea-made from processed urine, water and calcium chloride are needed. We can produce urea synthetically or it can be come from wastes. In a chain of chemical reactions, the microbes on sand are joined together like glue. The resulting brick looks like sandstone, but as strong as clay-fired brick or even marble. At first, sand is dried and placed into molds. Then the urea is mixed with lab-cultured bacteria and poured into the sand. It germinates the contact with the water and it feeds on the sand like a glue of calcium lactate. This type of bacteria is called genus bacillus. They continuously precipitate calcite over bricks with high impermeable layer, which increases the compressive strength and prevents the water into the brick and increase durability of the brick. In the part of metabolism of bacterial precipitate, a numerous amount of urea, which stimulates the urea to produce CO2 and ammonia, sequentially pH value increased in the surrounding, where ions Ca2+ and CO32- precipitate as CaCO3. Manufactured bricks are kept under the room temperature for 28 days to attain full growth. After the construction of the wall using bio brick the strength and durability of the brick increases because of the bacterial growth. The water component used in the mixture is to deliver the sedimentation reagent and to recycle a closed loop manufacturing system. When the water seeps through cracks of the brick and reaches the bacteria, again the biochemical reaction is stimulated and calcite precipitate is formed along the brick’s crack. Chemical reaction of bacteria in bio brick:
Ca2+ + CO3+ → CaCO3 ↓
CaCO3 → CaO + CO2
CaO + H2O → Ca(OH)2
Ca (OH)2 + CO2 → CaCO3 + H2O
There is still some work to be done, because the brick can be poisonous to groundwater as microbes convert the ammonia to nitrates. To solve the problem Doiser plans to design a system that would capture emissions and recycle them back to the brick-production cycle. Despite the challenges, the bacteria-brick is a promising solution to our traditional brick manufacturing process. For the normal manufacturing of the bricks it will take several weeks ago for the process. This process can be conducted in the very low temperature and the bricks are strong enough for use in houses, commercial buildings, and other structures, and it can be formed into various shapes and styles. Experimental data of bacterial bio brick and traditional brick:
Brick size cm (19*9*9)
Bacterial Brick
Water Absorbance
19.92 %
Compressive Strength
9.16 N/mm2
Traditional Brick
Water Absorbance
24.07 %
Compressive Strength
7.7 N/mm2
It is also found that none of bacterial bricks has fingernail impression and the bricks have clear metallic sound with no damage at the edges. The big advantage of the process is that unlike conventional bricks, which have to be fried at high temperature, it uses very little energy. It is expected by the experts that the innovation of Prof. Doiser’s low-energy bricks would help cut down on the use of cement, and it would be very beneficial for the environment as cement is one of the biggest consumer of energy, takes up about 6% of world’s energy. The bacterial growing brick is welcomed as it can be served as the substitute to these with same properties with smaller carbon footprint.