Settling can be very effective in removing small particle sizes. Settling is typically accomplished through a series of settling ponds or tanks. Screening is a process where the liquid manure passes through a screen. The solids are collected on the screen while the liquids pass through. The separation efficiency of a screening process depends on the size and design of the screen.
Screens can be stationary, rotating, or vibrating.
Stationary screens are mounted on an incline with the manure entering at the top edge of the screen. As the manure passes over the screen the liquids drain through the screen and the solids fall off the lower end. Rotating drum screens are designed to continuously rotate allowing liquid to pass through the screen and solids to move across the screen. This design keeps the screen holes open better because the screen is continually being scraped clean. Vibrating screens are level with the manure stream entering the middle of the screen.