Portable Liquid Filtration Device with Self-Cleaning Cross-Flow
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Solution Overview
Problem
Existing personal filtration devices for remote locations face challenges in efficiently removing microbiological pathogens and managing filter cake buildup, requiring manual disassembly and potential contamination risks during cleaning, and are cumbersome due to their design.
Innovation Solution
A compact personal filtration device with a hollow fiber filter cartridge that employs continuous cross-flow filtration, allowing self-cleaning without manual intervention, and includes a flush port to remove debris and air, maintaining efficiency and preventing contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dead-end filtration mode is used to remove microbiological pathogens, then filtration effectiveness is improved, but filter cake buildup reduces efficiency over time and requires manual cleaning
Solution Approach 1:
The system automatically switches between filtration mode and backflush mode in periodic cycles. During filtration mode, contaminated water is filtered through the hollow fiber membrane. When pressure differential exceeds a threshold, the system automatically reverses flow direction for a predetermined time to remove filter cake, then returns to filtration mode. This periodic switching maintains consistent water production efficiency while ensuring continuous pathogen removal.
Solution Approach 2:
The system performs self-cleaning through automatic backflushing without requiring manual intervention. A controller monitors the pressure differential across the membrane and automatically initiates backflushing when needed, using stored clean water to remove accumulated filter cake. This eliminates the need for users to manually disassemble and clean the filter, maintaining both effectiveness and productivity.
2Ease of repair
If manual disassembly is required for cleaning the filter cartridge, then filter cake can be removed, but contamination risk increases and ease of operation deteriorates
Solution Approach 1:
The system performs self-cleaning through automatic backflushing without requiring manual disassembly. A controller monitors the pressure differential across the membrane and automatically initiates backflushing when needed, using stored clean water to remove accumulated filter cake. This eliminates the need for users to manually disassemble and clean the filter, maintaining both effectiveness and productivity.
Solution Approach 2:
Clean water stored in a reservoir acts as an intermediary cleaning agent. During backflush mode, this stored water is pumped in reverse through the hollow fiber membrane to remove filter cake. This intermediary fluid enables the cleaning function without requiring direct manual contact with the membrane surface, reducing contamination risk while maintaining cleaning effectiveness.
3Reliability
If chemical disinfectants are used to treat water, then pathogen removal is achieved, but halogen-resistant protozoa cannot be removed and water palatability decreases
Solution Approach 1:
The system replaces chemical disinfection with a physical filtration mechanism using hollow fiber membranes with pore sizes of 0.01 to 0.1 micrometers. This mechanical/physical barrier effectively removes all microbiological pathogens including halogen-resistant protozoa like Cryptosporidium, without relying on chemical reactions that may fail against certain pathogens. The physical filtration also preserves water palatability by not adding chemical residues.
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 device effectively treats microbiologically contaminated water by continuously removing filter cake and air, ensuring consistent water production and safety without the need for manual cleaning, making it suitable for remote use.
Implementation Method 1
These personal filtration devices include a variety of water purification media that utilize a physical-barrier (i.e., size-exclusion) approach to removing microbiological pathogens
Implementation Method 2
A compact personal filtration device with a hollow fiber filter cartridge that employs continuous cross-flow filtration, allowing self-cleaning without manual intervention
Data Source
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AI summary
A portable liquid-filtration device includes an inlet port, a filtering portion including a filtering medium and fluidly coupled to the inlet port, a filtered-liquid output port fluidly coupled to the filtering portion, a flush port fluidly coupled to the filtering portion, and a manually activated pump assembly fluidly coupled to the inlet port, filtering portion, output port and flush port. The pump assembly is configured, when activated, to create a negative fluid pressure at the inlet port and a positive fluid pressure at the output port and the flush port. As a consequence of activation of the pump assembly., the filtering portion receives unfiltered liquid from the inlet port, the output port receives from the filtering portion only liquid traversing the filtering medium in a first direction, and the flush port receives from the filtering portion liquid traversing the filtering medium in a second direction different from the first direction.