In general, what is the percentage of dissolved solids in the total solids of wastewater?

The correct choice indicates that, in general, approximately 70% of the total solids in wastewater consist of dissolved solids. This is an important concept in wastewater treatment because total solids are categorized into two main components: suspended solids and dissolved solids.

Dissolved solids are those particles that pass through a filter and are usually composed of various organic and inorganic materials, such as salts, metals, and nutrients. Understanding the proportion of dissolved solids is crucial for operators as it influences treatment processes, affects water quality, and impacts the efficiency of equipment and treatment methods used in the wastewater treatment process.

The values assigned to the other options may suggest different percentages; however, these would not align as closely with standard observations in the field. It is well established in wastewater treatment literature that a significant majority of the solids present in wastewater are indeed in a dissolved form, thus validating that around 70% is a reasonable and commonly accepted estimate.