Total, dissolved and suspended solids

The total quantity of all substances (the sum of all dissolved and suspended solids) present in water is determined by evaporation of a water sample, drying of the evaporation residue at 105°C to a constant weight and weighing of the dry residue. Dissolved and suspended solids are separated (mostly by filtration) and the quantity of dissolved solids is then determined according to the amount of dry residue of the filtrate. 

Suspended solids can be indirectly determined from the difference between the total quantity of solids and dissolved solids, or directly after their separation from a sample of water and after drying. 

In drinking waters, the total quantity of substances is determined, in exceptional cases also that of dissolved and suspended solids. In surface waters all dissolved and suspended solids are determined. In wastewaters all suspended and dissolved solids aje determined, depending on the character of the sample [13, 14]. 

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If the total dissolved and suspended solids contents are too much to filter through the 0.4S micron filter, centrifuge the sample, decant, and then filter the aqueous phase (see Paragraph 8.4.7). Combine the solids from the centrifiige bottle(s), the particulate on the filter and the filter itself and proceed with the SDS extraction in Paragraph 9.5.4. 

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