Activated Carbon As A Support In Biotrickling Filters For The Removal Of Siloxanes In Sewage Sludge Biogas

Biogas generated during anaerobic digestion in wastewater treatment plants and landfills is considered as a resource of renewable energy, and its use assists initiatives to reduce global warming. In order to be used as high qualify fuel upgrading processes are needed, such as siloxanes removal. They might be found at low concentrations yet they possess abrasive properties during combustion in engines, thereby decreasing the efficiency of energy recovery systems. The most widespread technology commercially available for siloxanes removal is adsorption onto porous materials, though their regeneration or replacement is energy-consuming and expensive. On the contrary, biotechnologies may reduce investment and operating costs, increment treatment capacities and require low energy and chemicals. Siloxanes, though, challenge biotechnologies due to their low solubility into water, which hinders their gas-liquid mass transfer.Within this work, several batch studies were carried out suspending different activated carbons saturated with siloxanes in mineral medium. Siloxane mass transfer was investigated into ACs in presence of water, to select the most suitable AC for a biotrickling filter, being chemically activated carbons more suitable due to higher catalytic activity. A biotrickling filter was set up with and without the selected activated carbon in the packing bed, and were inoculated with enriched bacterial cultures isolated from sewage sludge from a wastewater treatment plant. A synthetic gas with siloxanes was treated counter currently to the mineral medium recirculation. The carbon proved to help the performance of the reactor increasing the removal efficiency, though its effect did not last long enough.