Improvement in filtration efficiency

1
Improvement in filtration efficiency

• Problems
• High specific cake resistance
• In cake filtration the cake is the target product
  
• The higher the filtration rate, the greater is
  the amount of cake
• The greater the amount the cake, the lower is the
  filtration rate
• Cake compressibility
• Blinding of filter media

• Solutions
• Pretreatment of feed/slurry
• Temperature
• Flocculent
• Coagulants
• Use of filter aid
• Forms porous structure
• Decreases specific cake resistance
• Decreases compressibility
• Is an impurity
• Reduces media blinding

2
Mode of operation in cake filtration

• Cake accumulation and removal in batch mode
• Filter funnel
• Filter press
• Leaf pressure filter
• Vacuum leaf filter
• Continuous cake accumulation and removal
• Horizontal continuous filter
• Rotary drum filter
• Slurry concentration by delayed cake filtration
• Slurry concentration by cross flow filtration
• Cake washing

3
Filter press
4
Filter press

• Applications
• Cake filtration
• Clarification
• Solid-liquid extraction
• Cake washing
• De-watering
• Industries
• Chemical
• Pharmaceutical
• Food
• Metallurgical
• Clays and Ceramics
• Dyes and Pigments
• Municipal Wastewater Treatment

• Advantages
• Compact design
• High throughput and process rate
• Disadvantages
• Labour intensive (needs dismantling)
• Batch operation
• High down time
• Capacity limited by internal space

5
Rotary drum filter
6
Rotary drum filter

• Applications
• Cake filtration
• Cake washing
• De-watering
• Industries
• Chemical
• Pharmaceutical
• Food
• Metallurgical
• Clays and Ceramics
• Dyes and Pigments
• Municipal Wastewater Treatment

• Advantages
• Continuous operation
• More or less compact
• Allows drying of product
• Disadvantages
• Low driving force (vacuum)
• Complicated design with many moving parts and
  seals

7
Vacuum leaf filter
8
Vacuum leaf filter

• Advantages
• Simple design
• General flexibility
• Semi-dry cake can be obtained
• Disadvantages
• Labour intensive
• High floor space requirement
• Cakes can fall off during transfer from one pan
  to another

• Applications
• Cake filtration
• Clarification
• Industries
• Chemical
• Pharmaceutical
• Food