Dry substance content (DS content)
The dry substance content (DS content), also called dry matter content, is the percentage of solids in a mixture of substances. The higher this proportion, the drier the mixture. The unit of DS content is [% by weight].
How is the DS content of a suspension calculated?
In order to calculate the DS content of a suspension, certain key data are necessary:
- density of the pure liquid (mostly water content)
- density of the pure solid (dry residue)
- density of the suspension under consideration
The densities of the respective components have the unit [kg/m³].
Formula for calculating the dry substance content of a suspension
Example procedure for determining DS content
Dry matter is measured in the laboratory. A weighed sample of the substance mixture (sometimes called fresh mass) is taken and heated to over 100°C in the drying room in order to evaporate the residual moisture (mostly water). The remaining dry residue is weighed and proportioned. This yields the dry substance content of the mixture.
Dry matter as a measure in the food industry
In centrifugation, the DS content is used to determine the quality of the separation result. In the food industry, for example, the fat content of cheese in the dry matter is indicated by this value.
Dry matter as a quality feature in sewage sludge dewatering
In sewage sludge dewatering, the consistency of the dewatered sludge or discharge product can be determined based on the DS content (paste at 6%, crumbly cake at >20%). The drier the dewatered sludge/solid, the more money sewage treatment plants can save during subsequent incineration.
 Michael Wächter: Chemielabor – Einführung in die Laborpraxis,1. Auflage, 2011
 H.G.Kessler: Lebensmittel- und Bioverfahrenstechnik [Food and Bioprocess Engineering], 4. Edition 1996