Active and Inert Cord Modules for Mixed Biofilm Nitrogen Removal
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Solution Overview
Problem
Existing membrane biofilm reactors face challenges in efficiently combining aerobic and anoxic/anaerobic zones for effective total nitrogen removal, as they require thick biofilms that are difficult to control and create diffusion barriers, leading to reduced reaction rates and energy inefficiencies.
Innovation Solution
A module comprising a combination of active and inert cords, where active cords have gas-permeable hollow fibers for aerobic support and inert cords without or with closed ends for anoxic/anaerobic support, allowing for separate biofilm zones within a single reactor, enhancing nitrification and denitrification processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If thick biofilms are used to combine aerobic and anoxic zones, then total nitrogen removal is achieved, but diffusion barriers are created and reaction rates are reduced
Solution Approach 1:
The invention segments the biofilm support structure into separate active cords (with hollow fibers for gas supply) and inert cords (without hollow fibers). This segmentation allows different zones to be maintained at different depths, enabling both aerobic nitrification at the surface and anoxic denitrification at deeper levels without creating a single thick diffusion barrier that would reduce reaction rates.
Solution Approach 2:
The invention applies local quality by providing gas supply only to specific locations (the hollow fibers of active cords) rather than uniformly throughout the entire biofilm mass. This creates localized aerobic zones around the hollow fibers while allowing anoxic conditions to develop in the bulk liquid and at deeper levels, optimizing both nitrification and denitrification processes simultaneously.
2Productivity
If thick biofilms are used for nitrogen removal, then total nitrogen removal is achieved, but energy consumption increases
Solution Approach 1:
By segmenting the support structure into active and inert cords distributed throughout the reactor, the invention enables efficient mass transfer and reduces the need for high-energy mixing operations. The segmented structure allows natural convection and diffusion to operate more effectively across multiple smaller zones rather than through a single thick biofilm layer.
Solution Approach 2:
The invention utilizes gas flow through the hollow fibers of active cords to create localized aeration and enhance mass transfer. This pneumatic approach reduces the need for mechanical mixing, thereby lowering energy consumption while maintaining effective nitrogen removal through the combined aerobic and anoxic processes.
3Speed
If mixed active and inert cords are used, then thin biofilms are maintained and reaction rates are enhanced, but device complexity increases
Solution Approach 1:
The invention merges active cords (with hollow fibers) and inert cords (without hollow fibers) into a single mixed support structure. This combination allows the system to maintain thin biofilms and high reaction rates while simplifying the overall device structure compared to separate reactors. The mixed cords are potted together in a single module, reducing the need for complex multi-reactor configurations.
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 combined module design facilitates efficient total nitrogen removal by maintaining thin biofilms, promoting high aeration fluxes and reaction rates, while reducing energy consumption and mixing requirements, and avoiding diffusion barriers.
Implementation Method 1
a combination of one or more inert cords and one or more active cords, potted in the at least one potting head, the active cords comprising hollow fiber gas transfer membranes
Implementation Method 2
a biofilm that receives a gas through a membrane has an aerobic zone and is used primarily for nitrification
Implementation Method 3
Another biofilm attached to an inert support has an anoxic or anaerobic zone and is used primarily for denitrification and COD removal
Data Source
Figure 1~2
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Figure 5~6
AI summary
A bioreactor has a biofilm that receives a gas through a supporting membrane and another biofilm attached to an inert support. The first biofilm is aerated through the membrane and provides nitrification. The other biofilm has an anoxic or anaerobic zone and provides denitrification. A module useful in the bioreactor has cords potted in at least one potting head. Optionally, some or all of the cords have a gas transfer membrane. The module may provide inert supports, active gas transfer supports or a combination of both types of support. Multiple modules may be assembled together into a cassette, the cassette providing inert supports, active supports or a combination. The module or cassette may have an aerator for mixing or biofilm control.