What is the role of microorganisms in sewage treatment?

Microorganisms play a crucial role in sewage treatment primarily through the decomposition of organic matter and pollutants. During the treatment process, these microbes break down complex organic compounds found in sewage, which includes human waste, food scraps, and other biodegradable materials. This biological process not only reduces the volume of organic material in the sewage but also transforms harmful substances into simpler, less toxic forms.

This decomposition is essential for making the sewage less harmful before it is released into the environment or further treated. The action of microorganisms is typically harnessed in both primary and secondary treatment stages of sewage processing, where aerobic and anaerobic bacteria are utilized to expedite the breakdown of organic pollutants efficiently.

The other options do not accurately capture the primary function of microorganisms. While sewage treatment may involve additional aspects such as the removal of heavy metals or physical debris, the direct and significant impact of microorganisms lies in their ability to decompose organic matter and pollutants, making this the most appropriate role attributed to them in the sewage treatment process.