What is the key to a stable and efficient DAF system? The answer is the result of the collaboration of multiple core components.
DAF is a proven and effective physical-chemical technology commonly used for many industrial and municipal applications.
So, what is the key factor that determines the effectiveness of its treatment? We can use an analogy:
Microbubbles are like “taxi”. The prerequisite is to produce enough taxis of the right size.
The gas-to-solid ratio is like the dispatch ratio of taxis to passengers. Only by dispatching the appropriate number of taxis based on the number of passengers (pollutant concentration) can transportation be completed efficiently and economically.
Coagulation reaction is to cause dispersed passengers (fine pollutants) to clump together, making them easier to carry in the vehicle.
The contact zone and separation zone are well-designed “boarding points” and “traffic routes” to ensure that the taxi (microbubble) can pick up the passenger (floc) and drive smoothly and quickly to the destination (water surface).
Therefore, the core of the DAF process is the “stable generation of sufficient quantities of microbubbles of suitable size,” and based on this, the precise control of the “gas-to-solid ratio.” It is the physical foundation of the entire process; without it, nothing that follows can function properly.
1. Physical Basis: Generation (release) of microbubbles. This is the physical basis and execution unit of the air flotation process.
Function: Microbubbles act as transporters, attaching to pollutants (oil, suspended matter, etc.) to form a “bubble-particle” complex, making it less dense than water and causing it to float.
Indicators: bubble size (ideally 10-100μm), uniformity, and stability.
Why is it the core issue?: If the bubbles are too large, they will float quickly, but their adhesion will be poor, their surface area will be small, and their carrying efficiency will be low. If the bubbles are unstable or uneven, the entire air flotation process will be uncontrollable.
Therefore, the core difference between all air flotation technologies (such as dissolved air flotation, vortex flotation, and induced draft flotation) lies in how to generate these microbubbles efficiently and economically.
2.Core Parameter: gas-to-solid ratio. This is the soul of quantitative process design and the key to process control.
Definition: Gas-to-solid ratio (A/S) refers to the ratio of the total amount of gas released to the total amount of suspended solids to be removed from the influent (usually by mass).
Function: It determines how many pollutants can be treated by how many bubbles are introduced.
Low gas-to-solid ratio: Insufficient bubbles prevent pollutants from being fully carried away and removed, resulting in poor treatment effect.
High gas-to-solid ratio can lead to an excess of bubbles, causing them to merge and grow larger, wasting energy, and even disturbing the existing scum layer.
Why is it the core issue?Because it connects water quality (pollutant concentration), process (pressure, reflux ratio), and target effect (removal rate).
Engineers calculate and adjust the gas-to-solid ratio to design dissolved air pressure, reflux ratio, or intake air volume to achieve optimal treatment results and economic benefits.
Besides the two core parameters mentioned above, other parameters also affect the entire system, such as the gas dissolution method and the choice of chemicals. In short, an efficient and stable DAF system is the result of the collaboration of multiple core components.
