What is the purpose of a trickling filter in wastewater treatment?

• A. To facilitate primary sedimentation.
• B. To chemically treat wastewater.
• C. To use microorganisms for degrading organic matter.
• D. To remove heavy metals from wastewater.

Answer: (C)

The purpose of a trickling filter in wastewater treatment is to utilize microorganisms for degrading organic matter. In this process, wastewater is distributed over a bed of media, typically consisting of stones, rocks, or plastic. As the wastewater trickles down through the media, a biofilm of microorganisms forms on the surface. These microorganisms feed on the organic pollutants in the wastewater, effectively breaking them down through biological processes such as respiration and decomposition.

This method is particularly effective because it allows for a large surface area for microbial attachment, enhancing the treatment efficiency. As the microorganisms consume the organic material, they convert it into biomass, carbon dioxide, and other by-products, which significantly reduces the organic load in the effluent.

The other options are not the primary purpose of a trickling filter. Primary sedimentation is a process that primarily removes solids from wastewater and occurs in a different phase of treatment. Chemical treatment involves the use of various substances to alter or remove contaminants, which is not the focus of a trickling filter. The removal of heavy metals typically requires specific treatment processes such as precipitation or ion exchange, not microbial action in a trickling filter system.