Total solids are comprised of TSS and what other component?

Total solids in wastewater are comprised of two main components: Total Suspended Solids (TSS) and Total Dissolved Solids (TDS). TSS refers to the particles suspended in the water that can be removed by filtration, while TDS includes both dissolved organic and inorganic materials that pass through a filter and remain in the water.

Total Dissolved Solids encompass a wide range of substances such as salts, minerals, and other small particles that contribute to the conductivity and chemical makeup of water. Therefore, the combination of TSS and TDS accurately represents the total solids present in a given sample of wastewater, making TDS the correct answer in this context.

The other options—VSS (Volatile Suspended Solids), CSS (Colloidal Suspended Solids), and FDS (Fixed Dissolved Solids)—either represent specific subsets of suspended or dissolved solids, or are terminology that isn't widely used in defining total solids in the context of wastewater treatment. Thus, they do not accurately complete the distinction necessary for understanding total solids in this context.