Product Description

THIOPAQ®: Biogas desulfurization

Highly Efficient H2S Removal from biogas and landfill gas at high uptime enables industries to consistently meet stringent gas quality requirements.

Biogas is an important renewable energy source. However, it always contains hydrogen sulfide (H2S). Removal of H2S is required for biogas upgrading, emissions reduction, and limiting corrosion of equipment such as gas engines, boilers and piping.

The THIOPAQ® was developed by Paques in cooperation with universities, research institutes and customers. Fundamental and applied research into biological, physical and mechanical aspects of the system resulted in a cost-effective and reliable process.

Through continuous development Paques is able to provide every customer with a tailor-made gas treatment solution that enables the customer to produce biogas with a very low hydrogen sulfide content at a low O&M cost and to fuel local gas-fired microgrids, or upgrade the gas to biomethane. Additionally, the elemental sulfur produced by the THIOPAQ® can be used as a high-quality fertilizer.



  • Proven technology, > 30 years operational experience
  • 325 THIOPAQ® references worldwide
  • Continuous innovation
  • In-house manufacturing and quality control
  • Deep H₂S removal (to < 25 ppm)
  • High uptime and reliable process
  • Low total cost of ownership
  • No air input into biogas
  • Production of high-quality fertilizer
  • No hazardous byproducts


Operation Principle:

The caustic solution in the THIOPAQ® scrubber is continuously biologically regenerated. In the scrubber, the gas containing H₂S is brought into contact with the wash solution in counter-current flow. Absorption of H₂S under slightly alkaline conditions (pH 8-9) enables a chemical reaction with hydroxide ions:

In the bioreactor the sulfide is oxidised into elemental sulfur by autotrophic colorless sulfidogenic bacteria:

The hydroxide used in the scrubber is regenerated in the bioreactor. Since the wash solution entering the scrubber at the top is sulfide-free, a high concentration difference between the liquid and gas phase makes it possible to obtain a very high H₂S removal efficiency: exceeding 99.5%. Both the small bleed stream (consisting mainly of sodium salts) and the produced sulfur are free of sulfide, so discharge is not a problem.



The THIOPAQ® scrubber can be applied to a wide range of biogas streams containing H2S and can be combined with all biological anaerobic systems, as well as treat natural gas and gas from oil & gas applications. After treatment in the THIOPAQ® scrubber, the biogas can be used in a gas engine or boiler or can be transported and used to fuel a local gas-fired microgrid. Upgrading to biomethane, which can be brought into the gas distribution network or used as fuel for vehicles is another possibility.

  • Standard designs for gas flows from 30 to 3,000 scfm
  • Standard designs for sulfur load up to 2,500 lbs/d
  • Custom-made designs for higher gas flows and loads
  • References for > 10,000 Nm³/h and sulfur loads > 5 tons S/day.

The THIOPAQ® process explained:

For more information, please visit our website at:

Contact us:
North America
Burlington (MA), USA
t + 1 781 362 4636


THIOPAQ® – USA – Dairy
640 scfm

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