Waste water substances can be break down by biological (e.g. by enzymes, bacteria, fungi or other microorganisms), chemical (e.g. oxidation, catalytic reaction) or by physical (e.g. light energy) processes.

Biodegradation takes place through metabolism by living organisms. Larger particles (e.g. dead cells) can be broke down into smaller fragments. They are then converted into molecular fragments by other organisms. The last step is often the breakdown into inorganic molecules such as water (H2O) or carbon dioxide (CO2). Furthermore, also inorganic substances can be broke down like ammonium (NH4 +) into nitrate (NO3-) (nitrification) and nitrate into nitrogen (N2) (denitrification).

In the biological wastewater treatment stage of municipal wastewater treatment plants, large amounts of degradable substances in the wastewater are made harmless by the microorganisms in the activated sludge. This activated sludge represents a wide variety of microorganisms and mostly has a flake structure. In the biological cleaning process of sewage treatment plants, the microorganisms are controlled and supported in such a way that the breakdown of the substances is optimized.

A large part of the microorganisms prefers a socialization with other microorganisms in a fixed form. Due to the symbiosis and protective functions generated by polymeric compounds, these granular microorganism societies could achieve significantly higher degradation rates and are more stable against temporary nutrient deficiencies or toxic compounds. With the S::Select® process, aerobic granular activated sludge is specifically generated and supported.


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