Decanter Centrifuge Calculator
Evaluate a decanter centrifuge with two transparent checks: bowl mechanics from diameter and speed, and a feed-to-cake solids mass balance. Estimate G-force, tip speed, hydraulic residence screening, dry-solids loading, cake and centrate production, volume reduction and polymer demand without implying a vendor performance guarantee.
Educational estimate. Calculator results are for planning and information only, not financial, tax, medical, legal, or engineering advice. Verify important decisions with official sources or a qualified professional.
Decanter Centrifuge Calculator
G-Force, Solids Loading, Capture & Cake Production
📐 Formula & Method
G-Force
Uses bowl inside radius and g = 9.80665 m/s². This mechanical acceleration calculation is deterministic.
Dry-Solids Loading
Daily loading equals hourly dry-solids load multiplied by operating hours.
Solids Capture and Cake
Cake volume is wet cake mass divided by cake density. Uncaptured dry solids leave in the centrate.
Centrate Solids
Centrate flow is estimated by wet-mass balance using liquid density of 1000 kg/m³; added polymer solution and dissolved constituents are excluded.
Approximate Pool Residence
This is a simplified cylindrical liquid-pool screening value. It excludes the beach, solids layer, feed zone and internal geometry.
Polymer Requirement
The result is active polymer mass, not neat emulsion or prepared-solution volume.
📋 How to Use
-
1
Enter sludge feed rate, daily operating time, feed total solids and feed density.
-
2
Enter expected solids capture and cake solids from representative testing, operating data or a vendor guarantee.
-
3
Enter wet cake density and active polymer dose for transport and chemical-use estimates.
-
4
Enter bowl diameter, cylindrical clarifying length, pond depth, bowl RPM and differential speed from the machine data.
-
5
Calculate mechanical G-force and tip speed plus feed, cake, centrate and polymer mass balances.
-
6
Check that the assumed capture, cake dryness and throughput are simultaneously supported by trials or vendor data.
🧮 Worked Examples
Municipal sludge validation case
10 m³/h feed at 3% TS and 1020 kg/m³, 95% capture, 20% cake solids, 1100 kg/m³ cake density, 3000 RPM and 0.45 m bowl diameter.
Daily polymer planning
The same feed operates 8 h/day at 6 kg active polymer per dry tonne.
Decanter Centrifuge Performance and Sludge Mass Balance
A decanter centrifuge cannot be sized reliably from bowl RPM or G-force alone. G-force describes centrifugal acceleration, but actual clarification and dewatering also depend on feed solids, particle size and density, viscosity, polymer conditioning, hydraulic and solids loading, pond depth, beach geometry, scroll design, differential speed and torque.
The most auditable preliminary calculation is a dry-solids mass balance. Feed volume, density and total solids establish the incoming dry-solids load. The selected capture determines dry solids reporting to cake, and selected cake solids determine wet cake mass and approximate transport volume.
Centrate suspended solids are estimated from the uncaptured dry-solids load and remaining liquid flow. The result is useful for return-load screening, but representative feed, cake and centrate sampling is required because dissolved solids, polymer carrier water and density differences are simplified.
Pond depth and differential speed create important tradeoffs. A deeper pond generally increases liquid residence and clarification but shortens the drying zone; differential speed changes solids residence, compression and conveying capacity. Neither setting has a universal optimum.
The previous generic sigma estimate has intentionally been removed. Sigma models require a defined centrifuge geometry and correction approach, and modern decanter performance cannot be responsibly inferred from an assumed length-to-diameter ratio. Use manufacturer curves, pilot testing and guaranteed duty data for equipment selection.
🔬 Methodology & Accuracy
Formula: Combines deterministic bowl G-force and tip-speed calculations with a user-defined sludge dry-solids mass balance, expected solids capture, cake concentration, approximate centrate flow/TSS, active-polymer demand and a simplified cylindrical pond residence-time check.
Data sources: US EPA Biosolids Technology Fact Sheet: Centrifuge Thickening and Dewatering (EPA 832-F-00-053); Flottweg technical references on centrifuge speed, pond depth and differential speed; Alfa Laval technical discussion of decanter process parameters and sigma-factor limitations.
Last reviewed: July 2026 · General formula used: G-Force · Accuracy: Results are precise to two decimal places using IEEE-754 double-precision arithmetic. Intended for educational and planning use only.
For informational purposes only. Results are estimates based on the inputs and formulas provided. For financial, tax, medical, or legal decisions, consult a qualified professional. Rates and regulations change — always verify current figures with official sources.