Conventional pollutant

A conventional pollutant is a term used in the USA to describe a water pollutant that is amenable to treatment by a municipal sewage treatment plant. A basic list of conventional pollutants is defined in the U.S. Clean Water Act. The list has been amended in regulations issued by the Environmental Protection Agency:

The Secondary Treatment Regulation contains national discharge standards for BOD, pH and TSS, applicable to sewage treatment plants in the U.S.

...
Wikipedia