In the past 2 years, Theia Air has been busy helping customers that were having major operating issues with their Gas Treatment Systems.  We have been replacing their iron sponge media with our H2S Rex media, eliminating operational issues and improving the performance

A few of the sites where we have replaced iron sponge technology recently are: {different pages ?)

  • JMEUA – Digester Gas Treatment  
    • The customer was using iron sponge technology to treat the methane from their digester. While the media worked and was inexpensive to purchase, the performance was not reliable and the cost to remove the media and dispose of continued to rise.
    • After some pilot testing at the facility, the customer decided to try our H2S Rex media. Once installed, the media lasted 40% longer than had been predicted or promised making it an even greater value.   The customer was pleased enough with the performance that they placed the media into both of their vessels, removing the iron sponge technology altogether.
  • HRSD: Digester Gas Treatment
    • The customer has a digester gas plant at one of their treatment plants. They are treating the H2S with a biological treatment system which cannot remove sufficient H2S to get them to their required level before going into their engines.  They have two (2) large treatment absorbers and
  • Eastern PA Utility – Landfill gas
    • Theia replaced iron sponge media in 6 large vessels which were filled with iron sponge media. The customer is treating 4300 cfm of landfill gas.  H2S levels have been gradually climbing and are presently near 1000 ppmv of H2S.
    • The iron sponge media created a number of operational issues at the plant including increases in pressure drop across the beds, depositing foreign matter into the gas itself and the need for regular watering.
    • Once spent, removing the media became a major challenge. The customer’s treatment system utilizes six (6) 14-foot diameter fiberglass vessels. The System vendor which provided it provides iron sponge in large nets which are designed to be pulled in and out of the vessel in one piece using a large machine. In order to use these nets, the entire top of the vessel must be removed which includes removing 100 bolts per vessel.  The cover must be lifted off and then placed on the ground away from the work on a level surface where it will not be damaged.
    • The customer attempted to utilize the nets as provided but the nets were not strong enough to break up the media and, instead, they tore making the removal of the media even more challenging than it was without the nets.
    • After the catastrophic failure of the net concept, the customer opted for loose iron sponge media. In order to remove the iron sponge media, the customer still had to deal with the arduous task of removing the lids.  They then removed the media using an excavator.  The customer was fortunate to have very skilled personnel who could operate the machine with sufficient skill and precision to allow them to complete these service events.
    • Even after the spent media is removed, the challenges did not stop. The media needed to be laid onto tarps and continuously wetted down to avoid fires.   The media was tested and considered to be hazardous waste and a long waiting period before the customer was able to secure a facility where they can dispose of the media properly.


Iron Sponge media does effectively remove Hydrogen Sulfide for a time. The idea behind the media and the manufacture of the media goes back many years.  It is a simple idea that works and is very inexpensive to manufacture and purchase.  For these reasons, it has been the most utilized H2S removal technology in landfill and digester gas applications as long as these applications have been around.   Eventually other iron-based medias were developed but suffer from some of the same issues.


While the media is inexpensive and relatively effective for a time, there are major operational issues which greatly reduce the value of these iron-based technologies. Theia developed our line of biogas media, like H2S Rex, to provide a treatment media that eliminates these issues

  • Flow:
    • Iron based media solidifies over time, creating channeling forcing the gas to go through only part of the media.  The solidification also blocks water distribution causing some areas to retain water and others to be dried out.   This issue causes the media to “break though prematurely” and causes the pressure drop to go up over time
    • H2S Rex media never clumps, or fouls, allowing the gas flow to remain consistent. The pressure drop through our media starts low and stays low.
  • Service:
    • Iron media solidifies creating large very hard chunks which are very difficult to remove. Removal service costs many times more than the media itself.    This service requires the service crew to enter the treatment vessel to break up these clumps before they can be removed.
      • One Iron Sponge vendor is offering a “solution” to this service issue. They are providing the media in large nets.  This technological breakthrough would allow the operator to remove the media in sections, 3 to 6 of these would be placed in a large vessel.  This “solution” has often created a situation that is arguably much worse then the loose media did
        • Iron Sponge forms such hard chunks that the nets are often not strong enough to dislodge the media and end up tearing. This creates an even more daunting challenge for service and creates a safety issue.
        • Use of this technology requires that the entire top of the treatment vessels be removable. As these vessels are fiberglass, this step requires the operator to remove over 100 bolts per vessel and then pull off a large fiberglass cover and place it out of the way somewhere.
        • Even when successful, this design requires the operator to pull out and place in large heavy objects suspended overhead and service technicians working below it. in order to “hook “the lower layers, a technician must often enter the vessel and secure the lifting apparatus to the net.
      • Theia media including H2S Rex is removed as easily as it is placed into the vessel. The media is removed via vacuum quickly and easily without entry of any technician into the vessel.
    • Disposal:
      • Disposal is also an issue with the spent iron sponge media. There are a number of safety issues including heat and flammability.  Additionally, the media can often be rendered hazardous with a limited number of disposal facilities that will accept the spent media
      • H2S Rex media is non-hazardous and completely safe to dispose of. Spent media is not even technically a waste and can be utilized as a soil amendment


These issues are well known and have been tolerated mostly due to the lack of options in the industry.