Define sludge in the context of sewage treatment.

In the context of sewage treatment, sludge refers to the solid material that settles at the bottom of treatment tanks during the wastewater treatment process. This material is a mixture of organic and inorganic matter, including bacteria, nutrients, and other solids that are produced as wastewater is processed.

As wastewater undergoes treatment, particularly during the primary and secondary stages, the solids eventually settle out and form sludge. This material can then be further processed, often via anaerobic digestion or other methods, to reduce its volume and potential environmental impact before disposal or reuse.

Understanding the role of sludge is crucial for sewage treatment workers, as proper management of sludge is essential for effective wastewater treatment and for maintaining the health of the environment.