Which solid classification is NOT considered in wastewater treatment?

In wastewater treatment, solid classification typically focuses on the nature of the solids found in the effluent. The primary classifications are organic and inorganic solids, as these directly relate to their composition and the biological processes involved in treatment. Organic solids are derived from living organisms, including plant and animal matter, while inorganic solids are non-living components, such as minerals and metals.

Color-related classification does not play a significant role in the categorization of solids in wastewater treatment. It does not impact how solids interact in the treatment processes or how treatment technologies are employed. Size-related classification, while relevant in contexts such as filtration, also doesn't encompass a broad categorization of solids that differentiates their biological or chemical behavior in wastewater treatment.

Thus, among the classifications presented, color-related solids are not a recognized category in the assessment and management of wastewater treatment processes.