What is a common issue faced when operating a dual media filter under heavy loading?

When operating a dual media filter under heavy loading, a common issue that arises is the shorter filter runs due to shearing of iron flocs. In this context, heavy loading can lead to a buildup of particles and flocs within the filter medium. As the flow rate increases, the mechanical forces can become significant enough to disturb the settled flocs, particularly those comprised of iron or other metals. This shearing effect destabilizes the flocs, resulting in them being washed out of the filter and leading to a decrease in filtration efficiency and an increase in the frequency of backwashing or filter replacement.

The process of shearing effectively disrupts the formation of stable floc structures and can cause operational challenges, necessitating the need for more frequent maintenance to ensure that water quality remains within acceptable parameters. As a result, dual media filters under heavy loading conditions may experience reduced operational efficiency and shorter filter runs, highlighting the importance of understanding and managing flow rates and loading conditions in water treatment operations.