MICP Vertical Barrier Using Ca-Bentonite to Reduce Permeability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Ca-bentonite-based vertical barriers exhibit poor hydraulic conductivity and higher costs compared to Na-bentonite, with the additional challenge of limited availability of Na-bentonite in countries like China.
Innovation Solution
A microbially induced carbonate precipitation (MICP)-based vertical barrier is developed using Ca-bentonite, ureolytic bacteria, and a cementing solution, which reduces permeability and increases strength by forming calcium carbonate precipitates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If Ca-bentonite is used instead of Na-bentonite, then manufacturing cost is reduced, but hydraulic conductivity (permeability) deteriorates
Solution Approach 1:
The patent applies parameter changes by modifying the physical and chemical properties of Ca-bentonite through MICP treatment. The calcium carbonate precipitation alters the pore structure and surface characteristics of the bentonite, transforming its hydraulic conductivity parameters to achieve both low cost and effective barrier performance
Solution Approach 2:
The patent creates a composite material system combining Ca-bentonite with microbially induced carbonate precipitation. This composite structure integrates the cost advantage of Ca-bentonite with the performance-enhancing effects of carbonate precipitates, achieving both economic and functional objectives
2Ease of manufacture
If Ca-bentonite is used, then manufacturing cost is reduced, but permeability coefficient deteriorates
Solution Approach 1:
The MICP process changes the physical parameters of Ca-bentonite by inducing carbonate precipitation that fills pores and modifies the pore network structure. This transforms the permeability coefficient parameter while maintaining the cost advantage of using Ca-bentonite
Solution Approach 2:
The patent utilizes porous materials principles by controlling the pore structure through MICP. The carbonate precipitation creates a dual-pore system that maintains some permeability for fluid flow while reducing overall permeability coefficient to achieve barrier function
3Reliability
If Na-bentonite is used, then hydraulic conductivity is improved, but manufacturing cost increases and availability decreases
Solution Approach 1:
The patent employs the principle of using cheaper Ca-bentonite instead of expensive Na-bentonite. By accepting that Ca-bentonite requires additional treatment to achieve comparable performance, the solution uses more economical materials that can be effectively treated to meet performance requirements
4Strength
If cement-mixed soil is used, then strength is improved, but permeability deteriorates and construction difficulty increases
Solution Approach 1:
The patent replaces the mechanical mixing and curing process of cement-mixed soil with a biological MICP process. The bacteria-mediated carbonate precipitation achieves strengthening and permeability reduction through chemical precipitation rather than mechanical cementation, avoiding the construction difficulties of cement mixing
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
The MICP technology effectively reduces the permeability coefficient and increases the strength of Ca-bentonite-based vertical barriers, while also significantly reducing manufacturing costs and carbon footprint.
Implementation Method 1
whose metabolism can produce ureolytic bacteria to catalyze urea hydrolysis
Implementation Method 2
combining of carbonate ions and ammonium ions produced after the hydrolysis of urea with free metal cations to form gelled crystals
Implementation Method 3
it enables filling the pores in the soil, and at the same time, achieving the effects of reduced permeability coefficient and increased of strength
Data Source
AI summary
The present invention discloses a microbially induced carbonate precipitation (MICP)-based vertical barrier, and a preparation method thereof, wherein a raw material of the vertical barrier includes in-situ soil, Ca-bentonite, a bacteria-containing culture medium, and a cementing solution. The bacteria-containing culture medium comprises flocculent ureolytic bacteria flora. The proportions of dry the Ca-bentonite to in-situ soil, the bacterial-containing culture medium to the cementing solution, and the cementing solution to the Ca-bentonite are specified to be 1:2, (2˜5):1, and (1˜2.5):10, respectively, to ensure optimal performance. The present invention addresses challenges related to the insufficient impermeability of Ca-bentonite-based barriers in the application of vertical barrier, and aims to reduce both the cost and carbon emissions associated with their construction.