Wastewater Lab · Settleable Solids
What Is the Settleable Solids Test?
Settleable solids is a settled-volume measurement; TSS is a retained-mass concentration.
Recognize The Cone
An Imhoff cone is a clear, cone-shaped graduated vessel that lets settleable material collect at the bottom. It provides a direct visual relationship between the wastewater sample and settled volume.
What The Result Represents
The test measures the volume of material that settles from a defined sample during the required period. Follow your lab procedure for the timing, reading details, and reported units.
Use With Process Evidence
Settleable-solids observations can support review of sedimentation or activated-sludge settling. Compare them with clarifier condition, TSS, blanket observations, and trends. One cone result does not prove one cause.
Reading The Cone
A common settleable-solids test fills an Imhoff cone to the 1 L mark with a well-mixed sample and lets it settle for 60 minutes. The result is read from the cone's markings in mL/L. For example, solids that settle to the 8 mL mark in a 1 L cone give 8 mL/L. Read the top of the settled layer, not stray floating material. A clear effluent may read less than 0.1 mL/L, while raw wastewater may read much higher.
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