High Effluent Turbidity / TSS
Effluent clarity degrades even though the settling test in the lab looks acceptable.
Symptoms: rising effluent TSS or turbidity readings, sometimes with a visible cloudy tint despite decent settling test results.
Probable Causes: clarifier hydraulic overload (exceeding SOR), short-circuiting from uneven flow distribution, wind-driven currents in outdoor clarifiers, or fine pin floc passing through the weir.
Troubleshooting Steps: 1) Calculate current SOR against design limits — bring an additional clarifier online if available. 2) Inspect influent well and baffles for uneven flow distribution causing short-circuiting. 3) Check weir levelness — even small elevation differences concentrate flow and velocity at low points. 4) If pin floc is the cause, address the underlying deflocculation issue rather than the clarifier itself.
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