Used to remove microbes in heat labile materials like;
vaccine
Antibiotics
Toxin
Serum
Sugar Solution
Purification of Air
Depth filters;
Porous filters
Retain particles throughout the depth of the filter
Previously used for bacterial purification;
Candle filters;
a. Chamberland filters: made of unglazed porcelain.
b. Berkefeld filters: diatomaceous earth.
Asbestos filters; Sietz filter & Sterimat filter
Sintered glass filters
Membrane filters;
Most widely used for bacterial filtration.
porous filters
retain particles larger than the pores size on the surface.
Pore size: m/c used- 0.22 µm
☆0.22 µm= removes most of bacteria, allows virus to pass through.
Sterilization controls (for membrane filtering): Serratia marcescens &
Brevundimonasa diminuta
Air Filters;
Used in: Biological safety cabinets and laminar air flow systems
☆HEPA Filters = High Efficiency Particulate Air Filters;
Pore size= 0.3 µm or more
Removes 99.97% of particles
☆ULPA Filters= Ultra Low Penetration/Particulate Air Filters;
Removes 99.9% of dust, pollen, mold, bacteria and any air borne particles of size 0.12 µm or larger