A common component of the gases produced during anaerobic digestion of wastewater sludge is siloxane. When methane gas containing siloxane is combusted, deposits of solid silica can collect within the equipment, causing maintenance and operational issues with downstream power generation equipment running on methane produced by the anaerobic digesters. Because of this tendency, Palm Beach County Water Utilities Department (PBCWUD) wanted to remove siloxane from the digester gas produced at its Southern Region Water Reclamation Facility (SRWRF).

Under a continuing design-build services contract, PBCWUD hired Globaltech to provide engineering design, permitting and installation of a digester gas siloxane removal system. The Work Authorization also included upgrades to the existing digester gas flare equipment: two new flow meters along with motorized valve operators to enable remote operation of the flare.

Project Achievements / Benefits

• Globaltech installed a gas equipment skid with two siloxane removal vessels equipped with media capable of removing siloxane to less than 100 parts per billion by volume. The skid was mounted on a concrete pad built next to the plant’s existing gas compressor skid.
• Globaltech conducted pre- and post-installation gas sampling to verify the proper level siloxane removal of the installed system.
• On the digester gas flare, Globaltech provided instrumentation and a power supply for the new motorized valves and connected the instrumentation to the PLC in the plant’s electrical room, giving PBCWUD improved process control.