What are solids in suspension separated by filtering a sample, drying and weighing residue?

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The concept is about measuring solids that are physically floating as particles in the water and can be captured by a filter. When you filter a sample, the solid particles that are suspended will stay on the filter. By drying that residue and weighing it, you quantify how much suspended material was present in the sample. This is a gravimetric way to determine suspended solids: the mass on the filter equals the suspended solids content.

Dissolved solids, by contrast, pass through the filter and would be measured from the evaporated filtrate rather than the residue on the filter. Total solids would involve weighing all solids by drying the whole sample without filtering, giving the combined dissolved and suspended solids. Colloidal particles can be part of the suspended solids if they are retained by the filter, but the key distinction for this method is capturing and weighing the material held on the filter.