Bio Thelys™

Bio Thelys™ Batch Thermal Hydrolysis

Bio Thelys™ is a complete sludge reduction solution that works in batch mode, combining thermal hydrolysis and anaerobic digestion.

By coupling the thermal hydrolysis and the anaerobic digestion, Bio Thelys™ offers better performance than a conventional digestion and optimizes sludge treatment by producing:

  • 25 to 35% less dry matter
  • 30 to 50% more biogas
  • No odours
  • A pasteurised digestate, for full control over the sanitation hazards and safe agricultural reuse.


Bio Thelys™ handles all kinds of organic, industrial or municipal sludge and can also handle grease.

Using Bio Thelys™ process allows to:

  • Reduce sludge volume
  • Improve sludge quality
  • Increase biogas production


Features and Benefits

Bio Thelys™ is a flexible and safe solution which produces a pasteurised digestate that is compliant with international standards e.g.: EPA class A (UAS) and ADAS Safe Sludge Matrix (UK)


Bio Thelys™ allows:

  • Reduced digester related investment for new installations
  • Reduced operating costs:
    • Less sludge to remove
    • At existing installations, the digestion capacity can be increased by handling new input.
  • An income which is generated from:
    • Either processing external input through co-digestion
    • Either selling the energy produced by co-generation or producing bio-methane


Bio Thelys™ is a solution that guarantees energy and environmental performance, thanks to:

  • Conversion into "green" electricity via co-generation
  • Bio-methane production (for injection into the network or as fuel)
  • Complete sludge pasteurization
  • Reduced carbon footprint of the facilities
  • Many possibilities for using biogas: with external input (co-digestion), energy self- sufficiency or even a positive energy footprint may be achieved by the plant.


Bio Thelys™ combines with other Veolia sludge treatment processes such as Athos™ (hydrothermal oxidation), Pyrofluid™ (incineration), BioCon™ (thermal drying), Solia™ (solar drying) and completes them to offer even more sustainable solutions.



  • Oxford, United Kingdom, 2013: 230,000 PE* and 26,000 t DS/year**
  • Esholt, United Kingdom, 2013: 760,000 PE and 32,800 t DS/year**
  • Tergnier, France, 2011: 30,000 PE and 1,600 t DS/year**
  • Monza, Italy, 2010: 750,000 PE and 15,800 t DS/year
  • Le Pertuiset SIVO, France, 2008: 80,000 PE and 2,000 t DS/year
  • Château-Gontier, France, 2007: 38,000 PE and 1,000 t DS/year
  • Saumur, France, 2006: 60,000 PE and 1,600 t DS/year

*PE: Population Equivalent
**including sludge external input

Dehydrated sludge first goes through a batch thermal hydrolysis phase during which steam is injected in reactors operating under specific pressure (9 bar) and temperature (165°C) conditions for approximately 30 minutes.





Bio Thelys™ is available under the 3 following configurations:


Lysis/Digestion (LD) Configuration

Thermal hydrolysis is performed on the whole or a part of the sludge stream prior to digestion.

This configuration reduces digester volume by a factor of 2 to 3, reduces the amount of sludge and guarantees that it is sanitized while increasing biogas production.

Using the LD configuration, the throughput of an overloaded digestion plant can be doubled, thus avoiding the need to build the additional digestion capacity.





Digestion/Lysis (DL) Configuration

The hydrolysis reactor is installed on a sludge recirculation loop combined with a digester. Thermal hydrolysis is applied to part of the digested sludge.

This configuration gives the client wide flexibility whilst using a smaller scale hydrolysis stage.

Using the DL configuration, digestion capacity of an existing installation can be increased by up to 30%.





Digestion/Lysis/Digestion (DLD) Configuration - Veolia Patent

Thermal hydrolysis is applied to all of the digested sludge from digester 1. Then the sludge is cooled and diluted before breakdown continues in digester 2.

This is the optimum formula in energy terms as it uses less steam while producing more biogas and electricity.

It also enables the greatest reduction in the amount of sludge to be produced.





Bio Thelys™ Brochure (532.46 KB)