Excessive head loss at a micro-screen unit could indicate which condition?

• A. Backwash flow rate is too high
• B. Screen is clean and functioning
• C. Drum speed too low, blinding or high TSS levels
• D. Feed temperature is too high

Answer: (C)

Excess head loss across a micro-screen means the flow resistance is rising, usually from solids adhering to or piling up on the screen. In a rotary micro-screen, the drum speed provides the cleaning action that keeps the screen pores open. If the drum speed is too low, that cleaning is reduced, so solids can accumulate on the screen and form a blinding layer that blocks flow. When TSS levels are high, more solids are available to clog the screen, making blinding occur more quickly and increasing the pressure drop. A screen that is clean and functioning would have lower head loss; feed temperature being too high isn’t the primary driver of excessive head loss, and while an overly high backwash rate affects cleaning, it doesn’t explain elevated head loss during normal operation.