A motor-driven blower, air header with branch laterals and a membrane diffuser grid feed a mixed-liquor cutaway in this simulator. A dissolved-oxygen probe mast reports the result. Change clean kLa, maximum uptake, temperature, basin volume and diffuser loss, or switch the blower off, and watch the oxygen balance settle.
• A real-time 3D view with numbered, clickable parts: motor-driven blower and inlet filter; air header and branch laterals; membrane diffuser grid; mixed-liquid cutaway; dO probe and status mast. Scene tools include home view, focus-selected-part, auto-rotate, expand and show/hide labels, and drag-to-orbit with pinch-to-zoom. • Experiment controls: clean kla (1–12 h⁻¹); maximum oxygen uptake (0–40 mg/L/h); water temperature (10–30 °C); basin volume (500–2000 m³); diffuser transfer loss (0–0.8 fraction); blower enabled, plus a show flow/process markers toggle, pause/resume, single-step buttons (0.1 s and 1 s), a playback-speed selector and a restart trial action. • Live readouts: dissolved oxygen; estimated saturation; oxygen transfer; oxygen uptake; predicted steady DO; effective kLa. A model response curve is drawn beside the 3D view and updates as you change controls. • A Curves & measurements tab with two live charts, the model equations as written in the simulator and snapshot readouts; an Experiments tab with 2 guided presets (blower outage; no oxygen demand) plus a model-verification bench, timestamped event log and copyable trial report. • A Learn & assess tab with 3 lessons (bubbles do not equal dissolved oxygen; biological uptake draws oxygen down; temperature changes saturation), a 2-question knowledge check with reset, and a written model-scope statement.
Rising bubbles show that air is being supplied, but dissolved oxygen (DO) is set by the balance between transfer and uptake. Transfer is proportional to the effective kLa and to the gap between saturation and the current DO, while biological uptake draws DO down. The model also reduces uptake near zero DO so the concentration never goes negative.
The Predicted steady DO value shows where the balance is heading, and the charts compare DO against the saturation level over time so you can see the approach to equilibrium after a change.
Warmer water holds less oxygen, so the simulator uses an empirical freshwater saturation curve that drops as temperature rises. The diffuser transfer-loss control reduces effective kLa while the blower is on, letting you see how fouled diffusers limit DO even at full air flow. Turning the blower off removes transfer and the bubbles and lets uptake pull DO down.
This is a well-mixed oxygen balance with surrogate oxygen-limited uptake. It has no full biomass model, salinity or bubble-size effects, and one animation second represents 15 process seconds.
kLa is the volumetric oxygen transfer coefficient, a rate constant that describes how quickly oxygen moves from air into the liquid per unit of the gap between saturation and actual DO. Higher values mean faster transfer.
With no air supply the transfer term is zero while biological uptake continues, so DO is drawn down. The simulator shows this with its blower-outage experiment.
The solubility of oxygen in water decreases as temperature increases. The model uses an empirical freshwater polynomial so the saturation concentration shown drops as you raise the temperature.
They reduce effective kLa by a chosen fraction to mimic diffusers that transfer less oxygen than when clean. It is a simple multiplier, not a detailed membrane or bubble-size model.