Fixed Bed Bio Reactor

Fixed Bed Bioreactor (FBBR) is one type of bioreactor used in biotechnology or waste treatment processes, where microorganisms grow and adhere to the surface of solid media (fixed bed) in the reactor. Here's a detailed explanation 👇

Working Principle

• Microorganisms form a biofilm on the surface of the media (such as stone, plastic, ceramic, or porous synthetic material).

• Liquid (substrate or effluent) is passed through this medium.

• The attached microorganisms decompose the organic matter in the liquid through biological processes (usually aerobic).

In other words, this reactor works by flowing liquid across a surface covered with active microorganisms.

Main Components

1. Reactor tank - the container where the fixed bed and liquid flow takes place.

2. Support media - where the microorganisms attach (e.g. bioballs, gravel, or plastic fibers).

3. Aeration system (for aerobic processes) - supplies oxygen to the microorganisms.

4. Water distribution and jetting system - ensures even liquid flow.

Pros

• High density of microorganisms (because they stick to the media).

• Stable to fluctuations in organic load.

• Easy maintenance, as microbes do not need to be constantly maintained in suspension.

• Efficient for treatment of effluents with low-medium organic concentrations.

Disadvantages

• Possible clogging if the media is too dense or high in solids.

• Oxygen and substrate diffusion can be a limiting factor if the biofilm is too thick.

• Usually less efficient for effluents with high solids content than activated sludge (suspended growth) systems.

Typical Applications

• Treatment of domestic and industrial wastewater (e.g. from food, dairy, or pharmaceutical plants).

• Production of bioethanol, enzymes and organic acids in industrial biotechnology.

• Also used in nitrification-denitrification processes in wastewater treatment.