Theia pioneered the use of activated carbon to treat landfill and digester gas and has been slowly replacing iron sponge at a number of locations around the country. As the focus for many sites has changed from using the gas on site to refining and putting into the gas pipeline, even more attention has been focused on more reliable means of removing the H2S from the gas to lower levels. Theia’s media has been the choice on many of these applications.
JMEUA Digester Gas:
The customer was using iron sponge technology to treat the methane from their digester. While the media mostly worked and was inexpensive to purchase, the performance was not reliable and the cost to remove dispose of the media continued to rise. Among the issues with iron sponge media:
-The media clumps and hardens, requiring entry into the vessels by personnel to break up the media. This presents a danger to the operators and greatly increases the cost and the time for replacement service.
-Spent iron sponge media is often considered a hazardous waste and disposing of the media is becoming more and more difficult.
-Removing the spent media is dangerous due to the pyritic nature of the media. The media often needs to be laid out onto a tarp and hosed down to keep it from lighting on fire.
Though interested in Theia’s media, the customer nonetheless wanted to see the media perform on their gas. Theia designed a slipstream treatment unit that allowed the customer to test the media in parallel head to head with the existing iron sponge media. After some pilot testing at the facility, the customer decided to try our H2S 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
HRSD is a large wastewater authority in eastern Virginia. Their Atlantic Plant has a sludge digester that produces methane with a significant level of H2S (hydrogen sulfide). The gas treatment system includes a biological treatment system followed by dry media vessels. The initial treatment system utilized iron sponge for this polishing step. Over time, the plant became dissatisfied with the performance of the iron sponge as well as the issues which accompanied this media.
Iron sponge was creating significant operational and safety issues. the media would need to be laid onto tarps and continuously sprayed down to prevent if from lighting on fire. Even after these extraordinary precautions, the media was difficult to deal with and the spent media has been considered hazardous waste.
The plant replaced the iron sponge with Theia’s H2S media and has enjoyed great performance as well as easy replacement services with no disposal issues since that time.
Idaho Digester – RNG
Theia was contacted by an engineer that specializes recovery, treatment and enhancement of methane created in digesters which process dairy waste. They had heard through mutual contacts about Theia’s H2S media and wanted to see if we could help.
Their customer(s) have purchased packaged gas handling and conditioning systems for taking the methane created by the sludge digesters on site and conditioning and purifying it to allow for use for power generation as well as for sale of the gas into the commercial gas market. The pretreatment technology offered by the system packager is not efficient or effective enough to handle the level of H2S (hydrogen sulfide) accompanying the methane.
Theia is working with this engineer and its customers to utilize our H2S media as well as equipment in some of the locations. Theia has shipped media to one of these customer locations to replace the media that was not able to deliver the performance that the customer needed. The media has been placed into the temporary vessels that the customer rented. The system is processing 500 cfm with 3000 ppmv of H2S.