What phenomenon is indicated by abnormally high head loss on recently backwashed filters?

Abnormally high head loss on recently backwashed filters is primarily indicative of air binding. This phenomenon occurs when air pockets become trapped within the filter media, disrupting the flow of water and causing increased resistance. When filters are backwashed, the flow direction is reversed to remove accumulated particles and debris. However, if air is introduced into the system during this process, it can lead to a situation where the air pockets inhibit water flow, resulting in higher pressure loss across the filter.

Understanding air binding is essential for maintaining the efficiency of filtration systems. It can exacerbate issues such as flow rate reduction and uneven distribution of water through the filter media, ultimately affecting the overall performance of the filtration system. Monitoring pressure levels and observing changes immediately after backwashing can help operators identify air binding issues and implement corrective actions to restore normal filter operation.