How to simulate substrate-inhibited fermenter (haldane kinetics)
A continuous chemostat where growth is genuinely **inhibited** at high substrate concentration — the real Haldane mechanism (mu = mu_max*S/(Ks + S + S^2/Ki)), a native solver kinetics option (params['ki']), not a decorative custom block (custom_block structurally can't change stream composition, so faking this through one would misrepresent the reactor's actual material balance). At the same dilution rate a plain Monod fermenter would consume nearly all the feed substrate; here more substrate survives unconverted and less biomass forms, because growth is suppressed in this concentration range — the whole point of modeling inhibition at all. A strongly inhibitory Ki can also make a nominally achievable dilution rate (D < mu_max) physically unreachable and the reactor washes out, since the Haldane mu(S) curve peaks at a finite S and falls again at higher S.
- 1Open the ready-made model
Open the "Substrate-inhibited fermenter (Haldane kinetics)" model in the MaximaLabs workspace — no install, no license. It loads live on the canvas, ready to edit and run.
- 2Confirm the thermodynamics
This process is modeled with the NRTL property package over ethanol, water — already selected, so the phase equilibrium and enthalpy are physically consistent from the first run.
- 3Review the flowsheet
The flowsheet chains BIO. Every block is a real, solvable unit op you can reconfigure on the canvas.
- 4Run the simulation
Click Run. The deterministic solver converges the material and energy balances (recycles included) and fills the live stream table — the AI never invents a number.
- 5Read the results and iterate
Inspect the converged streams, tweak a spec, and re-run — or ask the AI copilot to explain a result or diagnose a failed solve in plain English.
- Thermodynamics
- NRTL
- Components
- ethanol, water
- Unit operations
- BIO
Opens live on the canvas — free, no install.
Explore the model & flowsheetFrequently asked questions
- What does the Substrate-inhibited fermenter (Haldane kinetics) model simulate?
- A continuous chemostat where growth is genuinely **inhibited** at high substrate concentration — the real Haldane mechanism (mu = mu_max*S/(Ks + S + S^2/Ki)), a native solver kinetics option (params['ki']), not a decorative custom block (custom_block structurally can't change stream composition, so faking this through one would misrepresent the reactor's actual material balance). At the same dilution rate a plain Monod fermenter would consume nearly all the feed substrate; here more substrate survives unconverted and less biomass forms, because growth is suppressed in this concentration range — the whole point of modeling inhibition at all. A strongly inhibitory Ki can also make a nominally achievable dilution rate (D < mu_max) physically unreachable and the reactor washes out, since the Haldane mu(S) curve peaks at a finite S and falls again at higher S.
- Which thermodynamic method does it use?
- The NRTL property package, over ethanol, water — already selected. You can switch the method on the canvas before running.
- Which unit operations are in the flowsheet?
- It chains BIO. Every block is a real, solvable unit operation you can reconfigure, add to, or remove.
- Do I need to install software or buy a license?
- No. Substrate-inhibited fermenter (Haldane kinetics) runs entirely in your browser on MaximaLabs — free, no install, no license. Open the model to load it live and run the deterministic solver.
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