Tennessee Wastewater Operator Practice Exam

What is one limitation of trickling filters regarding the removal of specific pathogens?

1. Ammonia

2. Fecal coliform

3. Heavy metals

4. Organic matter

The correct answer is: Fecal coliform

Trickling filters are a type of biological treatment process used in wastewater treatment systems where microorganisms grow on a media and remove organic matter through biological interactions. However, one limitation of this process is its effectiveness in removing specific pathogens, particularly fecal coliform bacteria. Fecal coliform is a type of bacteria commonly found in the intestines of warm-blooded animals and often used as an indicator of water contamination by fecal matter. Trickling filters primarily focus on the removal of organic matter and nutrients, and although they can achieve some reduction in pathogen levels, their design and operation do not provide the necessary conditions for effective pathogen die-off or removal. The microbial populations within trickling filters work best on organic matter rather than specifically targeting pathogens like fecal coliform. Factors such as retention time and the conditions within the trickling filter (like pH, temperature, and oxygen levels) may not be optimized for killing or removing these bacteria, leading to a limitation in the overall removal efficiency of fecal coliform compared to other treatment methods designed specifically for pathogen reduction. In contrast, other options such as ammonia, heavy metals, and organic matter, are addressed either through different treatment processes or can be significantly reduced through trickling filters, which are more