Filtration Cake Layer Formation for Membrane Fouling Reduction
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Solution Overview
Problem
Waste water treatment systems using membrane bioreactors face issues with fouling and clogging due to the formation of a biomass layer, leading to high operating costs and the need for frequent chemical cleaning, and existing filtration methods are inefficient and unreliable.
Innovation Solution
A method utilizing a filtration cake formed from particles in the liquid, specifically activated sludge flocs, deposited on a porous support to separate solid particles of different sizes, allowing for efficient filtration of smaller particles while managing the biomass layer and reducing clogging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If membrane filtration is used for waste water treatment, then filtration efficiency is improved, but fouling and clogging occur leading to limited flow and high operating costs
Solution Approach 1:
The invention applies preliminary action by forming a filtration cake layer from activated sludge flocs before the actual filtration process. This pre-formed cake layer acts as a protective barrier that prevents direct contact between the membrane and suspended particles, thereby preventing fouling and clogging while maintaining filtration efficiency. The cake layer is established in advance and then used to filter the waste water, resolving the contradiction between filtration efficiency and flow capacity.
Solution Approach 2:
The invention introduces an intermediary substance - the filtration cake layer formed from activated sludge flocs - that mediates between the waste water and the membrane filter. This intermediary layer performs the actual filtration function, protecting the membrane from direct exposure to harmful particles. The cake layer serves as a buffer that maintains filtration efficiency while preventing fouling, thus resolving the technical contradiction.
2Manufacturing precision
If membrane filtration is used, then filtration performance is improved, but chemical cleaning and regeneration are required increasing operational costs
Solution Approach 1:
The invention applies self-service by using activated sludge flocs from the waste water itself to form the filtration cake layer. The system uses its own byproducts (sludge flocs) to create the filtering medium, eliminating the need for external chemicals or complex regeneration processes. This self-service approach maintains high filtration performance while significantly reducing operational costs associated with chemical cleaning and membrane regeneration.
3Manufacturing precision
If a biomass layer is formed on coarse mesh to improve solid-liquid separation, then separation efficiency is improved, but the layer thickness grows continuously requiring bottom aeration to control it
Solution Approach 1:
The invention extracts and removes the problematic continuous growth characteristic of biomass layers by using a different mechanism. Instead of relying on living biomass that requires aeration to control growth, the system uses dead or inert activated sludge flocs that form a stable cake layer. This extracted approach eliminates the need for bottom aeration systems while maintaining high solid-liquid separation efficiency, thereby reducing device complexity.
4Stability of the object's composition
If membrane coarse bubble aeration is used to control biomass layer thickness, then layer thickness control is improved, but operating costs increase significantly
Solution Approach 1:
The invention uses cheap, readily available activated sludge flocs to form the filtration cake layer, replacing the expensive and energy-intensive membrane aeration system. The cake layer is a disposable filtering medium that can be easily formed and removed without requiring continuous energy input for aeration. This approach provides stable biomass layer thickness control while dramatically reducing operating costs by eliminating the need for expensive membrane aeration equipment.
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 provides a more efficient and reliable filtration process, reducing fouling and clogging, lowering operational costs, and enabling effective biomass retention, with the filtration cake being easily removable and reusable, thus enhancing the overall efficiency of the waste water treatment system.
Implementation Method 1
a pressure difference across the filtration cake support (4), to provide a flow of liquid through the filtration cake support (4)
Implementation Method 2
providing a flow of the fraction comprising only the smaller particles towards and through the filtration cake (18)
Implementation Method 3
these solid particles are deposited on a filtration cake support being a porous member as a porous layer forming the filtration cake
Data Source
Figure 1
Figure 2a
Figure 2b
AI summary
The present invention relates to a method of filtering a feed and waste water treatment system using the filtration method. The method utilizes a filtration cake for the filtration, which filtration cake is formed by elements contained in a liquid having a different composition than the feed to the filtered. The invention relates in particular to a method for filtering a liquid containing solid particles of different sizes which utilizes a filtration cake formed at least partly and preferably only from particles contained in said liquid containing solid particles of different sizes. The particles of the filtration cake are deposited on a filtration cake support and the method involves separation of the liquid containing solid particles of different sizes into two fractions: one fraction containing solid particles above a certain size and one containing smaller particles, and filtering the fraction containing smaller particles through the filtration cake. According to preferred aspects of the invention, the feed to be filtered is activated sludge supernatant and the filtration cake is formed from floes of an activated sludge mixed liquor.