Which of the following is NOT one of the four wastewater streams?

The cooling water recirculation system is not considered one of the four typical wastewater streams. The primary wastewater streams generally include effluents that are directly contaminated or necessitate treatment before being released or reused.

Waste from floor drains typically contains contaminants and needs to be treated, making it a recognizable wastewater stream. Boiler blowdown is necessary to remove impurities that concentrate in the boiler, thus qualifying it as a wastewater stream. Waste from reverse osmosis systems involves the rejection of water containing contaminants and impurities, classifying it as another wastewater stream.

In contrast, cooling water recirculation systems generally involve the reuse of water that has been circulated through processes of heat exchange. While there may be some loss of water due to evaporation or blowdown, the majority of the water is not considered wastewater because it is reused and does not typically result in a contaminated effluent requiring treatment.