Walnut Shell Filter Draft Tube Backwash
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Solution Overview
Problem
Conventional walnut shell filter systems require high initial and maintenance costs due to mechanical backwash methods, generate excessive backwash fluid, and create dead spots where oil and suspended solids are not effectively removed, necessitating a more efficient and compact solution for wastewater treatment.
Innovation Solution
A system utilizing a draft tube system to roll the walnut shell filter media during backwash, employing a combination of air and water pulses to intermittently agitate and clean the media, reducing the need for mechanical equipment and minimizing backwash fluid usage, while ensuring thorough media contact and efficient contaminant removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical backwash methods are used, then the filter media can be effectively regenerated, but the initial costs and maintenance costs increase
Solution Approach 1:
The patent replaces mechanical backwash systems with a pneumatic system that uses air bubbles generated by a sparger. The air bubbles rise through the filter media, providing fluidization and regeneration without requiring mechanical impellers, pumps, or moving parts. This substitution eliminates mechanical seals and reduces maintenance requirements while maintaining effective media regeneration.
Solution Approach 2:
The patent employs pneumatic principles by introducing air through a sparger at the bottom of the filter vessel. The air bubbles create upward flow that fluidizes the filter media, enabling regeneration through bubble-induced mixing and suspension. This pneumatic approach replaces complex mechanical systems with a simpler gas-based mechanism.
2Reliability
If conventional backwash systems are used, then the filter media is cleaned, but significant amounts of backwash fluid are generated
Solution Approach 1:
The patent utilizes the phase transition of air to bubbles in liquid. By introducing air gas that transitions to bubbles within the water-saturated filter media, the system creates upward flow and fluidization without requiring large volumes of backwash liquid. The bubbles rise, carry media particles, and facilitate cleaning while minimizing liquid waste.
3Reliability
If high velocity backwash liquid is used, then the filter media can be turned, but dead spots remain where backwash fluid does not reach
Solution Approach 1:
The patent segments the backwash process into numerous small air bubbles rather than using a single high-velocity liquid stream. The sparger creates multiple bubble streams that distribute throughout the filter media, ensuring comprehensive coverage and eliminating dead spots. Each bubble acts as a localized fluidization point, collectively achieving uniform media turnover.
4Reliability
If mechanical mixing systems are used, then the filter media can be agitated during backwash, but the system footprint increases
Solution Approach 1:
The patent extracts the agitation function from mechanical components and transfers it to the pneumatic bubble system. The air bubbles themselves perform the mixing and agitation function that would otherwise require mechanical impellers or moving parts. This extraction eliminates the need for separate mechanical agitation equipment, reducing the system footprint.
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 pulsed backwash method reduces capital and maintenance costs, minimizes backwash fluid volume, and effectively addresses dead spots, enabling a more compact and efficient walnut shell filter system suitable for offshore applications and extended filtration periods.
Implementation Method 1
The air bubbles cause fluidization of the filter media and rolling of the particles in the filter media.
Implementation Method 2
Walnut shell filter media is known for its affinity for both water and oil, making it a desirable filter media and is typically used for the removal of oil from water and wastewater.
Data Source
AI summary
The present invention relates generally to a system and method for treating wastewater in a filter media apparatus having a draft tube system. The filter media may be walnut shell media.