Membrane Separation Device Dynamic Flux Control
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Solution Overview
Problem
Membrane separation devices in wastewater treatment face issues with sudden increases in transmembrane pressure due to fouling, requiring frequent cleaning and increased membrane area, leading to high operation costs and potential flux reduction.
Innovation Solution
Implementing a membrane filtration control unit that adjusts the permeated water flow based on inflow fluctuations, using aeration and chemical cleaning during halted operations to manage transmembrane pressure, and strategically setting the design flux to maintain stable filtration while reducing membrane area and operation costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If the membrane area is reduced and the design flux is increased to reduce operation cost, then the operation cost decreases, but the transmembrane pressure may rapidly increase
Solution Approach 1:
The control unit performs preliminary actions by monitoring transmembrane pressure in advance and automatically initiating relaxation processes or chemical cleaning before the pressure reaches critical levels. This proactive approach allows the system to maintain higher design flux with reduced membrane area while preventing sudden pressure increases through timely maintenance actions.
Solution Approach 2:
The system implements continuous feedback by measuring transmembrane pressure and automatically adjusting operation based on predefined criteria. When pressure exceeds thresholds, the control unit triggers cleaning processes, creating a closed-loop system that maintains optimal performance with reduced membrane area and lower operation costs while managing pressure increases.
2Stability of the object's composition
If a considerable margin is provided in the design flux to suppress sudden rise of transmembrane pressure, then the transmembrane pressure stability is improved, but the membrane area must be increased
Solution Approach 1:
The system transitions from a static design flux approach to a dynamic control system that automatically adjusts operation parameters based on real-time transmembrane pressure conditions. The control unit modulates flux and triggers cleaning processes dynamically, allowing the membrane area to be reduced while maintaining pressure stability through adaptive management.
Solution Approach 2:
The control system changes operational parameters (flux, cleaning frequency, chemical dosing) based on measured transmembrane pressure. By dynamically adjusting these parameters rather than relying on a fixed design flux with large margins, the system achieves pressure stability with smaller membrane area.
3Reliability
If the filtration operation is halted for relaxation process or chemical cleaning, then the membrane surface is cleaned, but the permeated water flow amount decreases
Solution Approach 1:
The control unit implements periodic relaxation processes and chemical cleaning at optimized intervals based on transmembrane pressure monitoring. This periodic maintenance approach minimizes downtime by performing cleaning only when necessary, thereby maintaining high productivity while ensuring reliable membrane performance through regular cleaning.
Solution Approach 2:
The system performs self-service by automatically monitoring its own performance and initiating cleaning processes when needed. The control unit autonomously manages the balance between filtration productivity and membrane maintenance, halting operations only when transmembrane pressure criteria are met, thus maximizing permeated water flow while ensuring reliable cleaning.
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 effectively manages sudden transmembrane pressure increases, reduces operation costs by minimizing aeration needs, and ensures stable membrane filtration by incorporating aeration and chemical cleaning processes during halted operations, thereby maintaining design flux and extending membrane lifespan.
Implementation Method 1
a membrane separation device which is immersed in the biological treatment tank and which obtains permeated water from water to be treated in the membrane separation tank
Implementation Method 2
a relaxation process so as to clean the membrane surface with an upward flow of the water to be treated by aeration
Data Source
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AI summary
The present invention provides a method for operating a membrane separation device capable of handling a sudden, unexpected rise in transmembrane pressure, while also increasing a design flux and reducing operating costs. The method includes a membrane filtration process for setting a flow amount M(t) of permeated water from the membrane separation device so as to satisfy a relationship expressed by the following equation: M(t) = KQ(t-1), where M(t) is a flow amount of the permeated water during a time period t having a predetermined length, K is a gain (> 1), and Q(t-1) is an amount of inflow of the water to be treated during a time period t-1 immediately prior to the time period t, and extracting the permeated water from the membrane separation device by the set flow amount M(t) of the permeated water, and a halt process for temporarily stopping the extracting the permeated water from the membrane separation device when a water level of a first water tank in which the membrane separation device is immersed, a water level of a second water tank which is in communication with the first tank such that a water level thereof is the same as that of the first water tank, or a water level of a third water tank into which overflowing water from the first water tank is flowing, becomes lower than a predetermined halt water level.