How are TDS solids characterized?

Total Dissolved Solids (TDS) refers to the concentration of dissolved substances in water, which includes a variety of solutes such as salts, minerals, and other compounds. When characterizing TDS solids, it is important to recognize that they are typically small enough to pass through filters of a certain pore size.

When we say that TDS solids are those solids that are small enough to pass through a 1.2-micron filter, we are indicating that these solids are in a dissolved state within the liquid, which allows them to move through such small filter pores. This characterization is useful in water treatment and analytical methods for assessing water quality since it helps in determining the level of dissolved materials that may affect the physical and chemical properties of the water.

The other options do not accurately define TDS. For example, solids that are too large to filter would not be considered part of TDS because they remain in the water as suspended solids rather than dissolved solids. Solids that are visible without drying do not accurately reflect the microscopic nature of TDS, which is composed of particles that cannot be visually separated from the water without chemical processes. Furthermore, TDS does not include solids that consist purely of gases, as gases do not dissolve in water