Why is secondary treatment also called biological treatment?

Sewage Treatment Plants (STPs) are those plants where sewage water is treated before its discharge into the rivers. Discuss the following: Why the secondary treatment is also called biological treatment?

Why do we prefer to call secondary wastewater treatment as biological treatment?

why do we prefer to call secondary wastewater treatment as biological treatment?

What is "Secondary treatment" of sewage?

In the treatment of waste water discharge, which treatment stage involves biological treatment?

Secondary sewage treatment is mainly is

Why is tetanus also called lockjaw disease?

Complete the missing links: Secondary treatment for polluted water are _________ and activated sludge method.