Underdrain Positive Pressure Prevents Liquid Downward Flow

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Solution Overview

Problem

In water or wastewater treatment units employing granular media, the air-only washing cycle faces challenges due to downward liquid flow, which causes maldistribution of air and clogs discharge ports, reducing the effectiveness of the washing process and necessitating costly underdrain replacements.

Innovation Solution

A method that maintains a constant liquid volume in the underdrain during the air-only washing cycle by introducing filtered water, creating a positive pressure to prevent liquid from flowing downward, thus stabilizing the granular media and preventing clogging of discharge ports without modifying the existing underdrain structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If air-only washing cycle is performed, then granular media is washed to remove impurities, but liquid flows downward into the underdrain causing maldistribution of air and clogging of discharge ports

Engineering Contradiction:

Improvewashing effectivenessVSAvoidliquid flow downward causing clogging

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system applies preliminary anti-action by introducing liquid into the underdrain before the air-only washing cycle begins, creating a positive pressure head that prevents downward liquid flow during the washing process. This preemptive measure counteracts the harmful downward liquid movement before it can cause clogging or maldistribution of air

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

Liquid introduced into the underdrain serves as an intermediary substance that mediates between the air washing process and the granular media. This intermediary liquid creates the necessary positive pressure to prevent harmful downward flow while allowing the air washing to proceed effectively

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If liquid is introduced into the underdrain to create positive pressure, then downward liquid flow is prevented, but additional liquid management requirements are introduced

Engineering Contradiction:

Improveprevention of media cloggingVSAvoidliquid introduction and management system

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The underdrain system is designed with multi-functionality, serving both as the traditional air distribution medium and as a receptacle for introducing liquid to create positive pressure. This universal design allows the same structure to perform multiple functions without adding significant complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system uses the liquid introduction mechanism to serve multiple purposes: creating positive pressure to prevent downward flow, maintaining stable liquid levels, and protecting the discharge ports. The liquid management system essentially serves itself by using the introduced liquid to maintain the conditions necessary for its own effective operation

Inventive Principle:

Principle #25Self-service

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 enhances the air-only washing efficiency, reduces clogging, and allows for continuous operation without the need for underdrain replacements, maintaining treatment unit performance and extending filtration cycles.

Implementation Method 1

directing a gas (e.g., air) into and upwardly through the underdrain and into a bed of granular media

Methodology Applied

Scientific EffectGas flow:

Implementation Method 2

directing a liquid, preferably filtered water, into the underdrain during the gas/air only cycle so that the volume of liquid in the underdrain remains constant

Methodology Applied

Scientific EffectHydraulic pressure: Pressure Increase

Implementation Method 3

creating a positive pressure on the underdrain to stabilize the volume of liquid present in the underdrain during the air only phase of a washing cycle

Methodology Applied

Scientific EffectPressure equilibrium: Pressure Increase

Data Source

PatentUS12059637B2Apparatus and method to prevent downward flow of liquid during a gas only washing cycle

Publication Date: 2024.08.13 ROBERTS MARKETING DE

AI summary

Devices and methods associated with these devices for significantly reducing or eliminating liquid (e.g., water) in a water or wastewater treatment unit above the underdrain from moving downwardly into the underdrain during an air only wash cycle of the treatment unit. The treatment unit can take many forms including but not limited to an upflow filter and a downflow filter. The treatment unit may include a filter bed having one or more layers of filter media supported by gravel above the underdrain. The treatment unit may also include an underdrain having a porous plate, slotted plate or slotted upper structure that obviates the need for gravel. Positive pressure is provided to the underdrain to overcome the downward force of the driving head in the treatment unit to significantly reduce or prevent liquid present in the treatment unit above the underdrain from moving downwardly into the underdrain.