At a Glance
Costs vary significantly with scale, bowl design, and throughput requirements. Use untangle.bio for project-specific estimates.
How Centrifugation Works
Centrifugation exploits density differences between solids and liquids by applying centrifugal force. Particles denser than the surrounding medium sediment outward toward the bowl wall, while the clarified liquid (centrate) is discharged from the center. The separation efficiency depends on the relative centrifugal force (RCF), particle size, and the density difference between phases.
Two Outputs
Sediment / Solids (heavy): Cells, cell debris, inclusion bodies, precipitates, and other dense particles that sediment under centrifugal force.
Centrate / Supernatant (light): Clarified liquid containing dissolved molecules — proteins, sugars, salts, and other soluble species.
Operating Modes
| Mode | Purpose | Description |
|---|---|---|
| Cell Harvesting | Cell removal | Separate intact cells from fermentation broth; product recovered in centrate (extracellular) or solids (intracellular) |
| Inclusion Body Recovery | IB collection | After cell lysis, recover dense inclusion bodies in sediment at 10,000–15,000 ×g |
| Debris Removal | Clarification | Remove cell debris after homogenization; product in centrate, debris in solids |
| Precipitate Collection | Protein recovery | Recover ammonium sulfate or isoelectric precipitates from solution |
Centrifuge Type Selection Guide
Rule of thumb: Disc-stack for continuous large-scale operations; tubular bowl for high-g, smaller-volume applications.
| Centrifuge Type | RCF Range | Best For | Common Use |
|---|---|---|---|
| Disc-Stack | 5,000–15,000 ×g | High throughput, continuous discharge | Cell harvest at production scale, yeast separation |
| Tubular Bowl | 15,000–20,000 ×g | Fine particles, high-g force | Inclusion body recovery, cell debris removal |
| Decanter | 1,000–5,000 ×g | High-solids slurries, continuous | Mycelial broths, high-density cultures |
| Basket / Bottle | 100–3,000 ×g | Lab/pilot scale, batch mode | Small-scale clarification, process development |
Best Molecules for Centrifugal Separation
| Molecule | Size / Density | Centrifugation Behavior | Use Case |
|---|---|---|---|
| E. coli | 1–2 µm / 1.1 g/cm³ | Sediments at ≥4,000 ×g | Cell harvest, inclusion body process |
| Yeast | 5–10 µm / 1.1 g/cm³ | Readily sediments at ≥1,000 ×g | Brewing clarification, yeast recovery |
| CHO Cells | 12–15 µm / 1.05 g/cm³ | Sediments at moderate g-force | mAb harvest clarification |
| IgG (mAb) | 150 kDa | Remains in centrate | Recovered in supernatant after cell removal |
| BSA | 66.5 kDa | Remains in centrate | Recovered in supernatant |
| Glucose | 180 Da | Remains in centrate | Passes through with supernatant |
Cost Considerations
Capital Cost (CAPEX)
Centrifuge CAPEX varies widely with bowl type, throughput capacity, and materials of construction. Disc-stack centrifuges for GMP bioprocessing represent a significant capital investment. Tubular bowl centrifuges are generally less expensive but limited in throughput. All designs require robust foundations and vibration isolation.
Key CAPEX Drivers
| Factor | Impact |
|---|---|
| Bowl type & size | Disc-stack > tubular bowl > decanter at equivalent throughput |
| Materials of construction | 316L SS standard; Hastelloy or titanium for corrosive feeds adds 2–3× |
| Throughput capacity | Primary cost driver — scales with bowl diameter and disc count |
| CIP/SIP capability | GMP-grade with automated CIP/SIP adds significant cost over basic designs |
Operating Cost (OPEX)
Centrifuges consume significant electrical power for the motor drive, especially at high g-forces. Maintenance costs include periodic bowl inspection, seal replacement, and bearing servicing. Cooling is often required for temperature-sensitive biologics. Unlike membranes, there are no consumable replacement costs per batch.
Frequently Asked Questions
What is the difference between disc-stack and tubular bowl centrifuges?
Disc-stack centrifuges use stacked conical discs to increase settling area and operate continuously with intermittent or continuous solids discharge. They handle high throughputs at 5,000–15,000 ×g. Tubular bowl centrifuges achieve higher g-forces (up to 20,000 ×g) in a simple cylindrical bowl but have limited solids capacity and require manual cleaning, making them better for small-volume, fine-particle applications.
Can centrifugation replace microfiltration for cell removal?
Centrifugation handles high cell densities more effectively than MF and avoids membrane fouling. However, centrifuges typically achieve 95–99% cell removal rather than complete removal. Many industrial processes use centrifugation for primary cell removal followed by MF or depth filtration for polishing to achieve a particle-free feed for chromatography.
What g-force is needed to remove E. coli cells?
E. coli cells (1–2 µm, density ~1.1 g/cm³) require at least 4,000–6,000 ×g for efficient sedimentation. Inclusion bodies from lysed E. coli are denser (1.3–1.4 g/cm³) and sediment readily at 10,000–15,000 ×g, allowing separation from lighter cell debris.
How does temperature affect centrifugation performance?
Lower temperatures increase broth viscosity, which reduces sedimentation velocity (Stokes’ law). However, many biologics require cold operation (4–8 °C) to maintain stability. The trade-off is managed by increasing residence time or g-force. High-speed centrifuges also generate heat from friction, requiring active cooling jackets.
Related Separation Techniques
Design a Centrifugation Step Into Your Process
Drag-and-drop centrifugation into your flowsheet, connect streams, and simulate with real mass balance.
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