When the biology goes sideways.
Process-control diagnostics for the symptoms every operator sees eventually — poor settling, bulking, foaming, nitrification loss, EBPR breakdown, and toxic inhibition — with probable causes and the response that actually works, built from the existing process-control library.
Start with the symptom, follow the cause.
The Troubleshooting Guide
A comprehensive walkthrough of common process control problems — poor settling, high SVI, rising sludge, foaming, pin floc, nitrification failure — with probable causes and step-by-step response.
Process Control Guide
Filamentous Organisms & Bulking
Identify the specific filament behind a bulking event — Type 1701, Nocardia, Microthrix, Thiothrix — and the matching correction, from DO and F/M adjustments to RAS chlorination and foam management.
Toxicity & Inhibition Response
Recognize a toxic slug, identify common toxicants (metals, cyanide, solvents, free ammonia), protect biomass during recovery, and document the event for pretreatment follow-up.
Phosphorus Removal & EBPR Failure Modes
Why biological phosphorus removal underperforms — anaerobic zone nitrate/DO carryover, VFA limitation, secondary P release — and how chemical-P polishing compares and combines with EBPR.
Dewatering Process Control
Polymer dosing, cake solids, and loading rates — the variables operators watch to keep dewatering efficient when feed sludge character shifts.
Sludge Thickening & Solids Balance
Gravity, DAF, and mechanical thickening: spotting thin underflow, low capture rate, and the solids-side bottlenecks that quietly limit the whole plant.
Quick links by problem.
Looking for the full set of process-control reference material — formulas, glossaries, and biology explainers, not just diagnostics? Browse the Process Control topic hub.
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