Dissolved Air Flotation Desludging with Ambient Airflow
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Solution Overview
Problem
Current desludging methods in dissolved air flotation units are inefficient, leading to significant liquid loss and increased costs due to the need for large amounts of water and chemicals, as well as high energy consumption and frequent maintenance requirements.
Innovation Solution
A modified DAF tank design incorporating fans to create ambient airflow that accelerates sludge over a weir, reducing liquid loss and enhancing sludge removal efficiency, potentially replacing traditional skimming methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional hydraulic flushing or mechanical skimming is used to remove sludge, then sludge removal is achieved, but significant liquid loss occurs and operational costs increase
Solution Approach 1:
The patent applies pneumatic principles by introducing air flow through a diffuser system at the tank bottom to create upward buoyant forces that lift and move sludge toward the weir. This pneumatic-assisted hydraulic flushing mechanism enables more effective sludge removal with reduced liquid loss compared to traditional purely hydraulic or mechanical methods.
Solution Approach 2:
The patent changes operational parameters by introducing controlled air flow rates, adjusting water depth, and modifying flushing intensity through the diffuser system. These parameter adjustments optimize the balance between sludge removal efficiency and liquid loss, allowing effective desludging with minimal water waste.
2Productivity
If continuous flushing is maintained to keep liquid level above overflow weir, then sludge removal is continuous, but water and chemicals are wasted
Solution Approach 1:
The patent implements periodic action by using intermittent air flow pulses through the diffuser system rather than continuous flushing. The air flow is activated in cycles to create sufficient buoyant force for sludge removal, then paused, achieving effective sludge clearance while minimizing water and chemical consumption during idle periods.
Solution Approach 2:
The patent enables self-service by allowing the sludge to be removed through natural buoyancy forces enhanced by periodic air flow. The system uses the sludge's own density difference and the periodic pneumatic assistance to achieve self-clearing without requiring continuous external energy input or chemical addition, reducing overall operational costs.
3Productivity
If mechanical skimmers are used to remove float, then sludge removal is achieved, but equipment complexity and maintenance requirements increase
Solution Approach 1:
The patent extracts and eliminates the complex mechanical skimmer mechanism from the system by replacing it with a simpler pneumatic-hydraulic approach. The diffuser system at the tank bottom creates upward air flow that directly moves sludge to the weir, removing the need for mechanical skimming equipment and associated complexity while maintaining effective sludge removal capability.
Solution Approach 2:
The patent substitutes the mechanical skimming system with a pneumatic-hydraulic system. Instead of using mechanical blades or scoops to remove sludge, the system uses air flow through the diffuser to create buoyant forces that naturally move sludge toward the overflow weir, eliminating mechanical components and reducing maintenance 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 approach reduces liquid loss by more than half, cuts desludging time in half, and decreases chemical usage and operational costs, allowing for longer intervals between desludging events, while also eliminating the need for additional equipment and labor.
Implementation Method 1
one or more fans (or blowers) at one end of the tank configured to blow the sludge toward and over the weir at the other end of the DAF tank
Implementation Method 2
The removal is achieved by dissolving air in the liquid under pressure and then releasing the air at atmospheric pressure in a flotation tank or basin. The released air forms tiny bubbles which adhere to the suspended matter causing the suspended matter to float to the surface of the liquid
Data Source
AI summary
A method and apparatus of minimizing the loss of liquid in a dissolved air flotation desludging process, is disclosed. The method and apparatus creates an ambient airflow over the top of the dissolved air flotation tank directed towards a weir at one end of the dissolved air flotation tank whereby sludge floating on top of the liquid is accelerated over the weir at a higher rate than the liquid, thereby conserving the amount of liquid lost over the weir.