DEfiltreringssystemer

DEfiltreringssystemer, or diatomaceous earth filtration systems, are filtration units that use diatomaceous earth (DE) as a filtration aid or medium to remove suspended solids from liquids. They are used in municipal and industrial water treatment, beverage production, dairy and food processing, pharmaceuticals, wastewater treatment, and pool filtration.

How they work: A thin layer of DE is deposited on a supporting medium within the filter vessel to form a porous filtration cake. Liquids pass through the cake, while fine particles become trapped in the DE layer. As filtration continues, the cake thickens and the pressure drop increases, signaling a backwash. Backwashing reverses flow to dislodge solids, after which the DE layer is re-coated or re-dosed to restore filtration performance.

Key components include the filter vessel with plates or grids, a controlled DE dosing system, a backwash system, and a control system that monitors differential pressure and flow. The DE powder is added in controlled amounts; spent DE is removed during backwashing and disposed according to local regulations.

Applications and performance: DE filtration yields very clear filtrates and can retain sub-micron particles, making it suitable for beverages (beer, wine), fruit juices, dairy products, and certain pharmaceutical liquids, as well as some municipal and industrial waters. It is also used in some swimming pool filtration systems.

Advantages and challenges: DE filtration offers high filtration efficiency and versatility across liquids with varying turbidity. Challenges include handling and dust control of the fine DE powder, disposal of spent DE, and ongoing maintenance to prevent channeling or fouling. Operators must follow safety guidelines for DE exposure.

Maintenance: Regular monitoring of differential pressure, timely backwashing, and re-coating with fresh DE are essential for consistent performance.