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Home / Solutions / Research & Development / Success Explorer / Athos™ process

Athos™ process

A clean technology to overcome sludge

In France, 1.1million tons of sludge (i.e. roughly 22kg per person) is indirectly and unknowingly produced each year by consuming drinking water which, once used, is transported to wastewater treatment plants. This water treatment produces waste in the form of sludge. However, the solutions available to treat this type of waste are not adapted to all local authorities.
In the 1990s, Veolia’s R&D launched research programs aimed at inventing economically and ecologically viable wastewater sludge treatment technologies. This was achieved by the Athos™ process which uses a hydro-thermal oxidation technique (HTO).

 

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Athos™ process: a godsend for the treatment of urban sludge

The sludge generated by industrial and urban wastewater has become a genuine issue since the early 90s. This raising awareness coincided with the reinforcement of the legislation.
Thermal treatment, landfilling and economic recovery are the three solutions to the urban sludge problem but these solutions cannot apply everywhere, for regulatory, geographical or agricultural reasons.

When research is enflamed by flameless combustion

In 1990 Veolia’s R&D researchers identified existing technologies which could be adapted to the specific urban sludge issue. In 1996, following a long testing and adaptation phase, a pilot system was built in Veolia’s water research Center in order to validate process engineering and viability. In 1998, a pre-industrial pilot unit was built in order to safely complete the industrial operation phase. The European Community funded part of the project as part of the “Life Environment” program. In France, ADEME (1) and water authorities also supported the project. The Veolia Water and Solutions and Technologies Division, the Technical Division and R&D worked together for four years to implement a prototype in Toulouse demonstrating the possibility of operating this process on an industrial scale.
Recognition came in 2002 with the city of Brussels’ decision to acquire the 1st wastewater treatment plant including the Athos™ hydro-thermal oxidation process.

(1) Agency for the Environment and Energy Management

A clean solution: hydro-thermal oxidation

Sludge is combined with an oxidizing gas (oxygen) which degrades its organic materials. The oxidation of sludge’s organic matter produces water, carbon dioxide and easily biodegradable organic compounds. The gases released during the operation are released into the air following specific treatment. Thus, an Athos™ reactor adapted to a population of 30,000 does not pollute more than a big truck. In addition, the heat released by this process is recovered to pre-heat the sludge, thereby reaching a thermal balance! Oxidation residue is a solid mineral which can be recycled in ceramic production processes (roof tiles, bricks, tiles etc.).

Malik Djafer in charge of Paris suburb studies for Veolia Water and the Athos™ program for Veolia’s water research Center at the time

“The hydro-thermal oxidation on which the Athos™ process is based produces a mineral residue, the “technosand”. Studies and tests are ongoing at the research Center to find applications for this residue in the construction industry, notably as a replacement for certain raw materials such as clay. (...) Thus, with Athos™, nothing is lost, everything is transformed!”