How does primary treatment primarily differ from secondary treatment?

Primary treatment primarily involves physical processes aimed at removing large solids and debris from wastewater. This stage typically includes methods such as screening, sedimentation, and grit removal. The primary goal is to reduce the organic and inorganic matter in the wastewater to prepare it for the subsequent stages of treatment.

In contrast, secondary treatment is characterized by biological processes, where microorganisms are used to break down organic matter. This stage often involves aeration tanks and biological reactors, highlighting the shift from a purely physical approach in primary treatment to a biological one in secondary treatment.

The other options suggest methods or processes that do not accurately represent the nature of primary treatment. For instance, the use of chemicals for disinfection typically occurs in later stages or as part of the secondary treatment, not primarily in primary treatment. Similarly, advanced filtration is not a characteristic of primary treatment, which focuses more on sedimentation and physical separation than on filtration technologies.