A radial clarifier cutaway reveals the center feedwell, the bridge with its rotating bottom rake, the sludge blanket, the perimeter launder and the underflow pump. Change feed flow, feed solids, clarifier diameter and sludge withdrawal, or fail the underflow pump, and follow the solids inventory.
• A real-time 3D view with numbered, clickable parts: center feedwell and inlet column; circular basin and perimeter launder; bridge, drive and bottom rake; sludge blanket volume; sludge withdrawal pump and outlet. 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: feed flow (100–400 m³/h); feed suspended solids (1000–4000 mg/L); clarifier diameter (12–24 m); sludge withdrawal (0–60 m³/h); scraper drive enabled; underflow pump failed, 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: blanket depth; sludge inventory; solids captured; current solids withdrawal; effluent suspended solids; inventory balance error. 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 (lose underflow; high withdrawal) plus a model-verification bench, timestamped event log and copyable trial report. • A Learn & assess tab with 3 lessons (the blanket is an inventory; hydraulic loading and solids loading differ; a stopped withdrawal system can overflow solids), a 2-question knowledge check with reset, and a written model-scope statement.
In this lumped model the sludge blanket is a mass inventory. Captured solids add to it, sludge withdrawal and any spill over the weir subtract from it, and blanket depth follows from inventory, an assumed constant underflow concentration and the basin area. The inventory balance error is shown so you can confirm that captured, withdrawn and spilled mass account for every kilogram.
Hydraulic loading (flow over area) and solids loading (mass feed rate) are different things: raising flow lowers capture efficiency through the overflow rate, while raising feed concentration changes mass loading even at the same flow.
If the underflow pump fails or withdrawal is set to zero while solids keep arriving, the blanket rises. Once the inventory exceeds the modeled working depth of 3.5 m, excess solids leave with the overflow and appear in the effluent suspended-solids value, which is the behavior the lose-underflow experiment demonstrates.
The scope is deliberately simple: a lumped inventory with a constant underflow concentration and an illustrative capture curve, no hindered-settling flux analysis or compaction, and scraper animation that does not change the bulk capture relation. One animation second represents one minute.
It is the layer of settled solids on the clarifier floor. Its depth reflects how much solids inventory the clarifier holds, which rises when capture exceeds withdrawal and falls when withdrawal exceeds capture.
Hydraulic loading is flow per unit surface area and mostly affects capture efficiency. Solids loading is the mass of solids applied per unit area and time, so it also depends on the feed concentration.
Withdrawal stops while feed continues, so the inventory and blanket depth rise. If the working depth is exceeded, solids spill into the overflow and effluent suspended solids climb.
No. The rake animation shows the equipment, but the bulk capture and inventory relations do not depend on the scraper, and the model does not include compaction or hindered-settling flux limits.