Rotating Filter Disk Microfiltration for Wastewater Solids Removal
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Solution Overview
Problem
Existing microfiltration machines for wastewater reuse face inefficiencies due to irregular filter disk surfaces, high energy consumption, and inability to meet stringent regulations for total solid suspended particle content below 5 mg/l, as well as maintenance and structural complexities.
Innovation Solution
The machine features filter disks with continuous and flat inner surfaces, reduced weight, and a simplified structure, allowing for higher rotation speeds, lower energy consumption, and improved filtration efficiency, along with enhanced backwashing mechanisms and a toroidal guard for splash prevention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If disk diameter is increased to handle higher flow rates, then filtration capacity is improved, but disk surface irregularity increases making particle collection difficult
Solution Approach 1:
The large disk surface is segmented into multiple smaller filter elements arranged in a modular pattern. Each filter element is a small, precisely manufactured component with consistent flatness, while the overall disk maintains large diameter for high filtration capacity. This segmentation allows manufacturing precision to be maintained at the element level while achieving high productivity at the system level.
Solution Approach 2:
Different zones of the disk are designed with locally optimized properties. The filter elements are concentrated in specific radial zones where flow patterns and particle deposition are most effective, while other zones accommodate structural support and washing mechanisms. This local quality approach ensures that each region of the large disk performs its specific function optimally.
2Reliability
If duct edges are positioned closer to disk surface to improve particle collection, then filtration efficiency increases, but risk of mesh damage from interferences increases
Solution Approach 1:
The collection duct is segmented into multiple smaller channels that run parallel to the disk surface. These segmented ducts can be positioned closer to the filter elements without requiring a single large clearance, as each duct serves a localized area. This segmentation allows efficient particle collection while maintaining safe distances to prevent mesh damage.
Solution Approach 2:
A protective intermediary layer or structure is introduced between the duct edges and the filter mesh. This intermediary element acts as a buffer that prevents direct contact and potential damage to the mesh while still allowing the duct to effectively collect particles. The intermediary maintains the necessary clearance while preserving filtration efficiency.
3Reliability
If disk rotation speed is increased to improve dynamic filtration effect, then particle blocking efficiency increases, but energy consumption increases
Solution Approach 1:
The disk rotation is optimized to operate at variable speeds with periodic adjustments rather than continuous high-speed rotation. During normal filtration, the disk rotates at a moderate speed to maintain the dynamic tangential effect. During backwashing cycles, the rotation speed is reduced or reversed. This periodic action maintains filtration effectiveness while significantly reducing average energy consumption compared to constant high-speed operation.
Solution Approach 2:
The system dynamically changes operational parameters including rotation speed, flow rate, and washing intensity based on filtration conditions. By adjusting these parameters in response to actual performance needs, the system maintains high filtration effectiveness when required while minimizing energy consumption during steady-state operation or between cleaning cycles.
4Strength
If disk mass is increased to withstand hydraulic loads, then structural strength is improved, but moment of inertia increases requiring higher motor power
Solution Approach 1:
The disk structure utilizes composite materials combining high-strength, low-density materials such as fiber-reinforced polymers or aluminum alloys with strategic reinforcement zones. This composite construction provides the necessary strength to withstand hydraulic loads while keeping the overall mass and moment of inertia low, thereby reducing the motor power required for rotation.
Solution Approach 2:
The disk is segmented into a lightweight central hub and peripheral filter element mounts connected by thin radial spokes. This segmentation places structural material only where absolutely necessary for strength, minimizing overall mass. The filter elements themselves provide additional structural support, allowing the use of lighter disk materials that reduce rotational inertia and motor power requirements.
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 configuration achieves significantly lower total solid particle content, reduced energy consumption, extended bearing life, and easier maintenance, while meeting stringent regulatory requirements and improving filtration flow rates.
Implementation Method 1
uses disks with filter meshes operating with the principle of 'dynamic tangential filtration', which implies that, as the disks rotate, the direction of the incoming flow is substantially parallel to the filter disks, whereby the particles that move over them have a velocity with a main component parallel to the flow and a second component perpendicular thereto
Implementation Method 2
Solid particles deposited on disk meshes are periodically removed by jet washing and backwashing means, directed against the outer surfaces of the disks, to urge them toward a collecting duct
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A continuous microfiltration machine for removing suspended solid particles from process and waste water comprises a container (2) with an inlet conduit (4) defining a flow direction (F), and having therein an influent chamber (7) for feeding the liquid to be filtered, a treatment chamber (8) with a bottom wall (9), at least one pair of filter disks (1 0) keyed to a shaft (1 2) perpendicular to the flow direction (F) and having inner filter surfaces (1 0') outer surfaces (1 0") and outer peripheral edges (1 5) in sliding contact with the bottom wall (9), an effluent chamber (1 7) for receiving the filtered liquid, with a discharge conduit (1 8), drive means (1 3, 14) for imparting rotation to the disks, first jet washing means (20) directed against the outer surfaces (1 0") of the disks (1 0) for removing the particles retained thereby, a first collecting duct (24) for collecting the removed particles, which is interposed between the disks (1 0) and has substantially parallel side edges (25) located at a predetermined minimum distance (D) from the inner surfaces (1 0') of the disks (1 0). The inner surfaces (1 0') of the disks are substantially flat and continuous surfaces, with a flatness error (ε) smaller than said predetermined minimum distance (D).