Ceramic Membrane Backwashing via Segmented Air Pressure
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Solution Overview
Problem
The existing membrane filtration systems face efficiency decline due to fouling, requiring frequent backwashing, which increases backwashing wastewater volume and necessitates large-diameter pipes, compromising equipment compactness and flexibility.
Innovation Solution
A method involving controlled air pressure to gradually drain and push out fouling substances from the membrane, using a ceramic filtration membrane with a substrate and separating layer, and positioning the backwashing air feed pipe below the filtrated water feed pipe to reduce wastewater volume and pipe diameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If high-pressurized air is supplied for backwashing to avoid using filtrated water, then water recovery is improved, but a large amount of water lodged in the membrane element is suddenly pushed out requiring large-diameter pipes
Solution Approach 1:
The backwashing process is divided into multiple sequential stages: first draining water from the secondary chamber, then gradually pushing out water from the membrane element using controlled air pressure, and finally performing high-pressure air backwashing. This segmentation allows water to be removed in manageable portions rather than all at once, enabling the use of smaller-diameter pipes while maintaining effective backwashing.
Solution Approach 2:
Before supplying high-pressurized air for backwashing, the system first drains water from the secondary chamber and gradually pushes out water from the membrane element using controlled air pressure. This preliminary action removes the bulk of water beforehand, so that when high-pressure air is supplied, only a small amount of remaining water needs to be expelled, eliminating the need for large-diameter pipes.
2Reliability
If backwashing is performed frequently to maintain filtration efficiency, then filtration performance is improved, but backwashing wastewater volume increases reducing operational efficiency
Solution Approach 1:
The system implements a continuous backwashing process where water is gradually pushed out from the membrane element using controlled air pressure, followed by high-pressure air backwashing. This continuous action thoroughly removes fouling substances without requiring frequent interruptions, maintaining filtration efficiency while reducing total backwashing wastewater volume through the preliminary draining stage.
Solution Approach 2:
The system recovers and drains water from the secondary chamber and membrane element before backwashing. This recovered water is removed in a controlled manner through the preliminary draining stage, reducing the volume of wastewater that needs to be handled during backwashing operations and improving overall operational efficiency.
3Reliability
If large-diameter feed pipes are used to facilitate backwashing wastewater flow, then backwashing effectiveness is improved, but equipment compactness and flexibility are compromised
Solution Approach 1:
Before backwashing, the system performs preliminary draining of water from the secondary chamber and gradual water removal from the membrane element using controlled air pressure. This preliminary action reduces the volume of water that needs to be expelled during backwashing, allowing effective backwashing to be performed through smaller-diameter pipes, thereby maintaining equipment compactness and flexibility.
Solution Approach 2:
The backwashing process is segmented into multiple stages with water removal occurring in portions rather than all at once. This segmentation allows the system to achieve effective backwashing without requiring large-diameter pipes to handle a sudden large volume of wastewater, preserving equipment compactness while maintaining backwashing effectiveness.
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 allows for effective backwashing without enlarging pipe diameters, maintaining efficiency and enabling compact, flexible equipment design by reducing backwashing wastewater volume and improving water recovery ratios.
Implementation Method 1
increasing air pressure so as to push out water remaining in the filtration membrane toward the primary side and thereby peel off the fouling substances
Implementation Method 2
a membrane element 1, formed with a large number of filtration channels 12 arranged in a porous portion 11 so as to be parallel to one another
Data Source
AI summary
A backwashing method incorporating a membrane filtration apparatus in which a ceramic filtration membrane including a substrate layer 11b having an extremely large number of filtration pores and a separating layer 11a having filtration pores smaller than those of the substrate layer is accommodated in a casing. Air controlled to a pressure p1 is supplied to the secondary side of the filtration membrane so as to drain the filtrated water in the membrane filtration apparatus gradually toward the primary side. After that, air pressure is increased to p3 so as to push the water in the filtration membrane toward the primary side together with the air, thereby peeling off any fouling substances. Unlike in conventional cases, a large amount of backwashing drain water is at no time drained at any one time, and thus, without reducing the effectiveness of backwashing, a backwashing drain pipe can be designed to have a small diameter. As a result, equipment can be reduced in size and the flexibility of equipment can be enhanced.