Enzyme-Producing Bacteria for Aggregate Cementation
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Solution Overview
Problem
The construction industry relies heavily on high-embodied energy materials like concrete and steel, which contribute significantly to carbon dioxide emissions, and traditional clay brick manufacturing also has a substantial carbon footprint due to its reliance on non-renewable resources and energy-intensive processes.
Innovation Solution
The method involves using enzyme-producing bacteria like Sporosarcina Pasteurii to induce calcite precipitation in loose aggregate, such as sand, to form a solid construction material through microbial-induced calcite precipitation (MICP), reducing the need for high-energy materials and minimizing carbon emissions by creating a locally sourced, biologically grown building material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If traditional clay brick manufacturing is used, then construction material is produced, but carbon dioxide emissions are high due to coal-powered kilns
Solution Approach 1:
The patent replaces the thermal/chemical system of coal-powered kilns with a biological system using urease-producing bacteria. The bacteria catalyze the decomposition of urea to produce ammonia and carbon dioxide in situ, which then react with calcium ions to form calcite that cements the aggregate. This biological substitution eliminates the need for high-temperature firing and external CO2 emissions.
Solution Approach 2:
The bacteria are applied to the loose aggregate and autonomously perform the cementation function. The urease-producing bacteria self-catalyze the chemical reactions needed to form calcite bonds between sand grains, eliminating the need for external energy input or complex manufacturing equipment. The system serves itself by using the bacteria's natural enzymatic activity to achieve the binding function.
2Productivity
If concrete masonry units with Portland cement are used, then manufacturing speed is improved, but carbon dioxide emissions from cement production increase
Solution Approach 1:
The patent replaces the industrial chemical process of Portland cement production with a biological process using urease-producing bacteria. Instead of heating limestone to high temperatures to produce cement, the bacteria catalyze urea decomposition and subsequent calcite precipitation at ambient conditions, achieving similar binding results without the high emissions associated with cement manufacturing.
Solution Approach 2:
The patent changes the fundamental parameters of the cementation process by operating at ambient temperature and pressure rather than the high temperatures required for Portland cement production. The biochemical pathway through urease catalysis allows the same functional outcome (aggregate bonding) to be achieved under vastly different, more environmentally friendly conditions.
3Productivity
If fired clay bricks are manufactured, then structural material is produced, but the process takes 3-20 days depending on equipment
Solution Approach 1:
The patent replaces the thermal processing system of fired brick manufacturing with a biochemical system. The urease-producing bacteria catalyze rapid calcite formation at ambient temperatures, achieving structural bonding in a fraction of the time required for traditional firing and cooling cycles, thereby dramatically reducing both manufacturing time and energy consumption.
Solution Approach 2:
The bacteria are applied to the loose aggregate in advance, and the cementation process begins immediately without requiring subsequent high-temperature firing or extended curing periods. The biochemical reactions proceed rapidly under ambient conditions, achieving structural integrity much faster than traditional methods that require days for firing and cooling.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces atmospheric carbon dioxide emissions by producing a sustainable, low-embodied energy construction material that can be locally manufactured, using a process that mimics natural sandstone formation, and allows for the integration of additional performance traits like strength and insulation.
Implementation Method 1
Urease producing Sporosarcina Pasteurii, a nonpathogenic, common-soil bacterium has the ability to induce the production of calcite through a chemical reaction
Implementation Method 2
the bacteria produce an enzyme, which in this case is urease, and use urea as a source of energy, producing ammonia and carbon dioxide
Implementation Method 3
The rise in pH forms a mineral 'precipitate,' combining calcium chloride with carbon dioxide
Implementation Method 4
The calcium ions contribute to the formation of calcium carbonate. The calcium carbonate fills at least some of the gaps between the loose pieces of aggregate, bonding to the aggregate
Implementation Method 5
The bacteria can then act as nucleation sites, attracting mineral ions from the calcium chloride to the cell wall, forming calcite crystals
Implementation Method 6
The hardened material is formed in a process referred to by Stocks-Fischer as microbial induced calcite precipitation [MICP]
Data Source
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AI summary
Methods for producing construction material utilizing loose pieces of aggregate (30), enzyme producing bacteria, an amount of urea and an amount of calcium ions. A first solution is prepared which includes urease which is formed by enzyme producing bacteria. A second solution is prepared which includes urea and calcium ions. The first and second solutions are added to the loose aggregate (30). The calcium ions contribute to the formation of calcium carbonate wherein the calcium carbonate fills and bonds between at least some of the gaps between the loose pieces of aggregate forming a solid construction material (92).