What is ATAD?
ATAD stands for Autoheated Thermophilic Aerobic Digestion. This technology uses the nutrients and metabolic heat contained in sludge to generate high temperatures in a digester.
The process takes place in a closed tank, which is agitated and has air injected into it in order to aerate the sludge.
It is used to treat sewage sludge.
When, where and why is it applied?
Its main application is in the treatment of wastewater in small towns and cities (i.e. those with 5,000-50,000 inhabitants).
It can be a good option for small and medium-sized plants, where the amount of sludge produced is insufficient for the implementation of energy recovery processes (anaerobic digestion)
During the process, the temperature is increased to 55 °C and remains at that level for 24 hours in order to sanitise the sludge and eliminate pathogens. The result is less concentrated sludge, which is then dehydrated and used as agricultural fertiliser.
Main components of the system
- Digester: an upright tank in which the sludge is mixed and aerated. This produces aerobic digestion, which is designed to generate heat.
- Recirculation pumps to agitate the sludge.
- Air injector: a jet of air is injected in order to add bubbles to the mixture, thereby enabling the microorganisms to obtain sufficient oxygen for metabolism to take place.