Algae Harvesting via pH-Induced Cell Disruption
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Solution Overview
Problem
Current methods for harvesting algae from dilute aqueous suspensions are economically and energy-inefficient due to high costs and energy requirements, particularly in separating algae from its growth media, with conventional methods like centrifugation and flocculation being costly and inefficient.
Innovation Solution
A method involving pH adjustment of the algae suspension to disrupt cell walls, followed by the addition of a partially water-soluble organic solvent like ethyl acetate, which allows for the separation and extraction of algal lipids into an organic layer that can be mechanically recovered, eliminating the need for centrifugation and dewetting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If centrifugation is used to separate algae from dilute suspension, then separation efficiency is improved, but capital and operational costs become extremely high
Solution Approach 1:
The patent changes the chemical parameter (pH) of the aqueous suspension to disrupt algal cell walls and alter the charge state of algal surfaces. This parameter change enables the algae to aggregate and become separable by simple decanting or filtration, replacing the need for expensive centrifugation while maintaining high separation efficiency
Solution Approach 2:
The patent introduces an intermediary substance (metal salt such as aluminum sulfate or ferric chloride) that acts as a bridge between the algal cells and the separation process. This intermediary coagulates the algae by neutralizing surface charges and forming flocs, enabling easy separation without expensive equipment
2Ease of manufacture
If flocculation is used to separate algae from dilute suspension, then operational cost is reduced, but sedimentation rate becomes slow and biomass yield is low
Solution Approach 1:
The patent performs preliminary pH adjustment before the separation process to disrupt cell walls and expose hydrophobic regions of algal lipids. This preliminary action prepares the algae for more effective coagulation and faster sedimentation, increasing both the rate and yield of biomass recovery
Solution Approach 2:
The patent creates composite floc structures by combining metal salt coagulants with pH adjustment, forming larger and denser aggregates that settle faster. The combination of chemical coagulation and pH-mediated cell wall disruption creates a more effective composite separation mechanism than either method alone
3Reliability
If conventional harvesting methods are used on dilute algae suspension, then algae can be separated from growth media, but energy input and processing time become excessive
Solution Approach 1:
The patent replaces the mechanical energy-intensive centrifugation system with a chemical process (pH adjustment and coagulation) that enables separation through simple gravity-driven decanting or low-energy filtration. This substitution dramatically reduces energy input while maintaining reliable separation effectiveness
Solution Approach 2:
The patent induces a phase transition in the algal suspension by changing pH, which causes cell wall disruption and alters the physical state of algal cells from dispersed to aggregated. This phase change enables rapid separation through gravity rather than requiring continuous mechanical energy input
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 method significantly reduces energy input and costs by allowing for efficient separation and extraction of algal lipids with high yield, using low-cost, environmentally friendly chemicals, and can be completed in less time with fewer steps compared to conventional methods.
Implementation Method 1
adjusting the pH of the dilute aqueous suspension to cause disruption of the algal cell walls and exposure of the hydrophobic tails of the algal lipid bilayer
Implementation Method 2
adding at least one organic solvent to the dilute aqueous suspension; and mixing the dilute aqueous suspension
Implementation Method 3
exposure of the hydrophobic tails of the algal lipid bilayer
Implementation Method 4
waiting for formation of an organic layer from the dilute aqueous suspension; and recovering the organic layer
Data Source
AI summary
The present disclosure generally pertains to methods for the harvesting of biomass, in particular algae, from dilute aqueous suspension. In one embodiment, the method comprises the steps of: adjusting the pH of the dilute aqueous suspension to cause disruption of the algal cell walls and exposure of the hydrophobic tails of the algal lipid bilayer; adding at least one organic solvent to the dilute aqueous suspension; and mixing the dilute aqueous suspension. The method may also include the steps of: waiting for formation of an organic layer from the dilute aqueous suspension; and recovering the organic layer. The organic layer rises to the top of the dilute aqueous suspension, allowing for mechanical separation or decanting of the organic layer.