What is a Micron
Micron Sizes: Understanding Particle Filtration
A micron (1 μm - aka a micrometer*) is a unit of measurement equal to one-millionth of a meter
It is commonly used to describe the size of particles, including microorganisms, and the pore size of filters.
Understanding micron sizes helps ensure the right filtration system is chosen to address specific contaminants effectively.
*The symbol for micron is μm, which is a lowercase Greek letter mu followed by the letter "m"
Common Micron Sizes
1. Human Hair: ~50-100 microns
2. Sand: ~60-200 microns
3. Pollen: ~10-100 microns
4. Bacteria:
• Range: ~0.2-2 microns
• Example: E. coli (~0.5-2 microns)
5. Protozoa:
• Range: ~4-15 microns
• Example: Giardia (~8-15 microns)
6. Viruses:
• Range: ~0.02-0.3 microns
• Example: Norovirus (~0.02-0.04 microns)
Filter Micron Ratings
• Coarse Filters (5-100 microns):
• Remove visible particles like sand, rust, and debris.
• Microfiltration (0.1-5 microns):
• Removes bacteria and protozoa but not viruses.
• Ultrafiltration (0.01-0.1 microns):
• Removes bacteria, protozoa, and some viruses.
• Nanofiltration (0.001-0.01 microns):
• Removes most viruses, bacteria, and dissolved contaminants.
• Reverse Osmosis (0.0001 microns):
• Removes nearly all microorganisms and dissolved salts.
Importance in Filtration
• Bacteria Removal: Requires filters with pores ≤1 micron.
• Virus Removal: Needs ultrafiltration, nanofiltration, or reverse osmosis (<0.01 microns).
• Protozoa Removal: Achievable with filters ≥5 microns (e.g., ceramic or microfilters).
