Bi-On SIGMA is a hydrogen sulphide (H2S) scavenger, consisting of iron hydroxide, Fe(OH)3, blended into a proprietary pelletized support.

Bi-On SIGMA has been developed to work efficiently with biogas that has 95% or less relative humidity. System design should take into account the need to avoid intensive condensation onto the pellets, since it could end into a loss of the media capacity and the impossibility to perform a proper regeneration

Once the media is spent, it may be regenerated by blowing ambient air through the bed

No H2S is released while the regenerating process takes place. Taking into consideration that one cycle is defined as the completion of these two reactions, Bi-On SIGMA may undergo at least 10 cycles before exhaustion and disposal.

In the absence of oxygen, Bi-On SIGMA displays a higher H2S breakthrough capacity than a caustic impregnated activated carbon. Furthermore, spent activated carbon cannot be regenerated and hence must be disposed of after just one cycle.


  • Avoids equipment corrosion problems.
  • Minimizes fire risk due to its high ignition temperature.


Bi-On SIGMA is specially designed for removal of H2S from anaerobic gas streams, e.g. biogas. In addition avoid corrosion and damage equipment caused by H2S.