Principle of Rotary Drum Filter
The rotary drum filter operates on the principle of vacuum filtration, where a vacuum is applied inside the drum to draw liquid through the filter medium, leaving solids behind.
Construction
Rotary Drum: A rotating cylindrical drum covered with a filter cloth.
Vacuum System: Creates a vacuum inside the drum.
Slurry Tank: Contains the slurry to be filtered.
Discharge System: For collecting filtrate and removing filter cake.
Agitator: Keeps the slurry in suspension.
Working
The drum rotates partially submerged in the slurry tank.
A vacuum is applied inside the drum, drawing liquid through the filter cloth.
Solids are retained on the outside of the drum, forming a filter cake.
As the drum rotates, the filter cake is dried by air or other means.
The cake is removed by a scraper or other mechanical means.
The filtrate is collected and drained off.
Uses
Mineral processing
Food industry (e.g., sugar refining)
Wastewater treatment
Pharmaceutical industry
Merits
Continuous operation.
Suitable for large-scale filtration.
Produces a relatively dry filter cake.
Demerits
High initial cost.
Requires significant space.
Not suitable for very fine particles.
Maintenance can be complex.