What role does activated sludge play in wastewater treatment?

Activated sludge plays a crucial role in wastewater treatment as it is a rich mixture of microorganisms, including bacteria and protozoa, that effectively break down and decompose organic matter found in sewage. This biological process is essential for reducing the concentration of pollutants in wastewater before it is released back into the environment. The microorganisms utilize the organic matter as food, converting it into biomass, carbon dioxide, and water while also ensuring that harmful pathogens are significantly reduced during the treatment process.

While filtration processes remove larger debris, heavy metal removal is typically achieved through other means, such as chemical precipitation or adsorption, and aeration is a necessary component in maintaining aerobic conditions for the microorganisms but does not define the primary role of activated sludge. The key function of activated sludge is its involvement in the biological treatment stage, whereby it enables efficient decomposition of organic materials, thus making option B the most accurate representation of its role in wastewater management.