Membrane Filter Chemical Clean via Permeate Side Diffusion
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Solution Overview
Problem
Existing methods for cleaning microfiltration and ultrafiltration membranes in water filtration systems face challenges such as high chemical solution volume requirements, waste generation, and incomplete removal of foulants, leading to permeability deterioration over time.
Innovation Solution
A method involving the introduction of a cleaning agent to either the feed or permeate side of the membrane, with controlled pressure and diffusion to contact and remove foulants, using a concentration gradient and pulsed pressure to dislodge solids, and repeated cycles with backwashes to minimize chemical usage and waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If membranes are immersed in chemical cleaning solution for full chemical recovery, then membrane permeability is restored, but large volumes of chemical solution are required and large volumes of chemical waste are generated
Solution Approach 1:
The cleaning process is divided into two distinct stages: a maintenance clean stage using minimal chemical solution to prevent foulant buildup, and a full chemical recovery stage only when necessary. This segmentation allows the system to maintain membrane performance with significantly reduced chemical consumption compared to continuous full chemical cleaning
Solution Approach 2:
The system implements periodic maintenance cleaning cycles rather than continuous chemical cleaning. The cleaning frequency and duration are adjusted based on monitored membrane performance, enabling chemical solution to be applied only when needed to restore permeability, thereby reducing overall chemical usage and waste generation
2Productivity
If frequent backwashes are performed to reclaim membrane permeability, then some foulants are removed, but foulants continue to build up and permeability deteriorates over time
Solution Approach 1:
Chemical cleaning agents are introduced as an intermediary substance to enhance the backwash process. The chemical solution facilitates the removal of adhered foulants that mechanical backwashing alone cannot eliminate, thereby restoring membrane permeability more effectively and preventing long-term permeability deterioration
Solution Approach 2:
The system changes the chemical composition and concentration parameters of the cleaning solution based on the specific type and amount of foulants detected. By adjusting these parameters, the cleaning process becomes more targeted and effective at removing stubborn deposits that accumulate during normal operation and resist standard backwashing
3Reliability
If chemical cleaning agents are used to dissolve accumulated solids, then membrane performance is recovered, but the amount of chemical agent required and waste generated increases
Solution Approach 1:
Instead of applying full chemical cleaning continuously, the system uses partial chemical action during maintenance cycles - applying just enough chemical solution to prevent foulant accumulation and maintain permeability. Full chemical cleaning is reserved for periodic recovery when membrane performance degradation exceeds a threshold, thereby optimizing chemical usage
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 significantly reduces chemical consumption and waste, enhances membrane permeability recovery, and improves operational efficiency by targeting foulants effectively without the need for large chemical volumes.
Implementation Method 1
allowing the cleaning agent to contact the permeate side of the membrane for a predetermined time, and contact the pores of the membrane
Implementation Method 2
introducing a fluid containing a cleaning agent to the permeate side of a membrane
Data Source
AI summary
A method of cleaning a porous polymeric membrane having a feed side and a permeate side including the steps of introducing a fluid containing a cleaning agent to the permeate side of a membrane allowing the cleaning agent to contact the permeate side of the membrane for a predetermined time, and contact the pores of the membrane, or introducing a fluid containing a cleaning agent to the feed side of a membrane; applying a transmembrane pressure to force the fluid containing the cleaning agent from the feed side to the permeate side of the membrane; allowing the cleaning agent to contact the permeate side of the membrane for a predetermined time, and contact the pores of the membrane. Preferably a concentration gradient between the feed side fluid and the lumen side fluid containing the cleaning agent causes cleaning agent to diffuse into the feed side fluid. Pressure may be applied to the fluid containing a cleaning agent to dislodge, where present, dissolved and undissolved solid from the membrane pores. The pressure may be applied in a pulsed fashion, and can be by way of compressed air at a pressure not more than the membrane's bubble point. The methods of the present invention may be preceded by, or followed with a backwash.