What is the role of fats and greases in the context of sewage composition?

Fats and greases play a significant role in sewage composition, primarily as a pollutant. They are considered a primary pollutant because they can lead to several environmental and operational issues. When fats and greases enter the sewage system, they can accumulate and form solid blockages, which can obstruct pipes and hinder sewage treatment processes. This accumulation can disrupt the functioning of treatment facilities and increase maintenance costs.

Moreover, fats and greases can lead to the production of harmful byproducts when they undergo anaerobic digestion, contributing to unpleasant odors and creating conditions that may harm aquatic life if the sewage is not treated properly. Their presence can also inhibit the effectiveness of biological treatment processes, as they can create an unfavorable environment for the microorganisms involved in breaking down organic matter.

In contrast, while fats and greases can provide some biodegradable material, they predominantly disrupt sewage systems and treatment processes, thus reinforcing their classification as a primary pollutant.