Trickling Filters and RBCs · Fixed-Film Treatment
What Lives in a Trickling Filter Biofilm?
A biofilm is more than a layer of bacteria. It may also hold fungi, protozoa, algae, and other organisms. The mix of life changes with the wastewater, the oxygen supply, the temperature, the load, and the location in the unit.
Some bacteria feed on organic matter that contains carbon. That organic matter is the food the biofilm lives on. Operators measure it with the biochemical oxygen demand test, or BOD. A lower BOD after the unit means the film ate more of the food. A page later in this module introduces the tests you will see.
Some fixed-film units also grow nitrifying bacteria, which change ammonia into nitrate. Nitrifiers grow more slowly than most carbon-removing bacteria, so they are easier to upset. The nitrification page in this module explains why that matters.
You will see this community on your rounds. Its color, its thickness, and the worms and fly larvae living in it tell you how the unit is doing. Do not judge the plant by one organism. Later modules show what normal and abnormal growth look like.
Key point: The biofilm's makeup reflects the treatment conditions and the pollutants that reach it.
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Trickling Filters and Rotating Biological Contactors
This page comes from the course. It covers biofilm, trickling filter equipment, recirculation and loading, lab tests, sloughing, RBCs and common operating problems, one step at a time, with short knowledge checks and a certificate of completion.
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