Rotating Drum Bioreactor with Perforated Aeration Tubes
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Solution Overview
Problem
Existing biological water treatment methods using biomass fixed on media, such as MBBR and RBC, face challenges including high operating costs due to continuous air injection, maintenance difficulties, moderate oxygenation capacity, inefficient biomass distribution, and unpredictable processing efficiency, particularly when treating large volumes of water.
Innovation Solution
A system featuring a rotating drum with permeable walls and free media occupying 30-80% of its volume, which alternately submerges and emerges from water, utilizing perforated tubes for aeration, allowing for efficient mixing and biofilm detachment without dedicated aeration, thus reducing maintenance and energy costs while enhancing oxygenation and biomass distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If continuous air injection is used in MBBR reactors to achieve aeration and fluidization, then oxygenation capacity is improved, but operating cost increases and maintenance difficulty increases
Solution Approach 1:
The patent employs periodic air injection through controllable valves instead of continuous aeration. Air is injected in cycles during specific phases of the bioreactor operation, providing sufficient oxygenation while dramatically reducing energy consumption and eliminating the need for continuous monitoring and maintenance of aeration systems.
Solution Approach 2:
The bioreactor system utilizes the natural movement and mixing of the slurry phase to distribute oxygen throughout the biomass. The periodic air injection combined with the natural convection and mixing processes creates self-sustaining oxygen distribution without requiring complex continuous aeration infrastructure that needs frequent maintenance.
2Productivity
If free media are used in MBBR reactors to increase biofilm surface area, then treatment capacity is improved, but device complexity increases due to media retention requirements
Solution Approach 1:
The patent employs a porous floating support structure that provides extensive surface area for biofilm attachment while maintaining buoyancy. This porous foam material naturally retains the biomass and prevents washout without requiring additional mechanical retention systems, screens, or complex internal structures, thus simplifying the overall device design while maximizing treatment capacity.
3Ease of operation
If rotating biological contactors are used to achieve aeration without air injection, then operating cost is reduced, but oxygenation capacity becomes moderate and limits biomass development
Solution Approach 1:
The system uses periodic air injection during specific operational phases to provide high oxygenation capacity when needed, rather than relying solely on passive atmospheric exposure. This timed aeration strategy delivers sufficient oxygen for robust biomass development while maintaining low overall energy consumption and simple operation.
4Volume of stationary object
If biomass is fixed on media in traditional systems, then reactor size is reduced, but homogeneous biomass distribution becomes difficult to achieve
Solution Approach 1:
The patent employs a slurry-phase bioreactor system where the entire mixture of biomass, substrate, and liquid phase is agitated and circulated as a uniform slurry. This approach eliminates the need for fixed media while maintaining compact reactor size, and the continuous mixing ensures homogeneous biomass distribution throughout the reactor volume.
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 system efficiently treats large volumes of water with reduced maintenance and energy costs, achieving homogeneous biomass growth and stable biofilm detachment, resulting in consistent treatment efficiency and reduced suspended solid matter, while offering a larger surface area for biofilm development compared to traditional methods.
Implementation Method 1
a rotating drum defining an internal volume, said drum being capable of rotating about a horizontal shaft
Implementation Method 2
the rotating drum being disposed in the tank and being intended for being partially submerged in the water contained in the tank
Implementation Method 3
at least one hollow tube extending in parallel to said horizontal shaft fixed to said wall of said rotating drum within said rotating drum, said at least one hollow tube having a perforated longitudinal section comprising a set of orifices
Implementation Method 4
said at least one hollow tube being designed to get filled alternately with water and with air when said rotating drum, partially submerged in the water contained in the tank, is put into rotation
Implementation Method 5
free media, having a surface suited to the development of a biofilm, disposed within the rotating drum
Implementation Method 6
the free media occupying a volume ranging from 30% to 80% of the internal volume of the rotating drum
Implementation Method 7
having a wall that is at least partly permeable to water
Implementation Method 8
the free media occupying a volume ranging from 30% to 80% of the internal volume of the rotating drum
Data Source
AI summary
A system for biologically treating wastewater comprising a rotating drum disposed within a tank. Biofilm carriers are contained in the drum. One or more hollow tube aerators are secured inside the drum to a perforated wall that forms a part of the drum. As the drum is rotated within the tank, the mixing of the biofilm carriers with the wastewater therein and the action of the hollow tubes aerates the wastewater in the rotating drum.