Wastewater treatment is the process of removing household and institutional wastes from the water supply. Household wastes, also called sewage, such as debris that comes from toilets, sinks, kitchen garbage disposals, baths, and showers. Industrial wastes can be some of the same, though will usually also include contaminants like manufacturing by-products that are flushed through the factory’s or other commercial facility’s sewage system. These are processed out in wastewater treatment to get recycled water to put in use and also reduce the harmful components in the water.

Source:

https://ecequip.com/the-impact-of-wastewater-treatment-to-our-environment/