Microfiltration range — Microfiltration for removing suspended material such as bacteria generally uses membranes with pore sizes in which range?

Introduction:
Microfiltration membranes are commonly used to remove bacteria, cell debris, and other suspended solids from liquids. Correctly identifying the pore size range is important for selecting between microfiltration, ultrafiltration, and nanofiltration technologies in downstream processing.

Given Data / Assumptions:

• Bacterial cell diameters typically range from roughly 0.5 to several micrometers.
• Membranes are characterized by nominal pore size.
• Pressure-driven, crossflow or dead-end operation.

Concept / Approach:
Microfiltration is widely defined as spanning approximately 0.1 to 10 μm. Pores smaller than roughly 0.1 μm belong to ultrafiltration or tighter classifications; pores much larger than a few micrometers drift toward coarse screening rather than membrane microfiltration.

Step-by-Step Solution:
Relate target (bacteria) to pore size needed for retention.Recall standard membrane taxonomy: microfiltration 0.1–10 μm, ultrafiltration ~1–100 nm, nanofiltration ~0.5–2 nm by effective MWCO behavior.Select the range that matches microfiltration: 0.1 to 10 μm.

Verification / Alternative check:
Supplier catalogs list microfiltration cartridges at 0.1, 0.2, 0.45, and 1.0 μm nominal ratings for bioburden control, consistent with this range.

Why Other Options Are Wrong:

• Ångström ranges (options b and d) are ultrafiltration or nanofiltration scales.
• 20–30 μm are coarse screens or prefilters, not typical microfiltration membranes.
• 0.005–0.05 μm (5–50 nm) is ultrafiltration, not microfiltration.

Common Pitfalls:
Confusing nominal pore size with absolute retention rating; forgetting that real retention depends on particle shape and operating conditions.

Final Answer:
0.1 to 10 μm