Abatement of siloxanes in sewage biogas: coupling adsorption and biological treatments

The anaerobic digestion of organic matter in landfills and wastewater treatment plants causes the formation of biogas that can be used in energy conversion systems for the production of electricity and heat, injection into the gas grid or as a fuel for vehicles. However, biogas includes a wide range of trace contaminants, from which siloxanes are the most harmful since, during biogas combustion reactions, they promote serious damage to energy conversion units. The elimination of siloxanes is mandatory for the biogas energy applications and the most commonly used technology to reduce their concentration in biogas is adsorption into activated carbon. Despite the high efficiency in the elimination of siloxane, the frequent replacement of exhausted activated carbon and the consequent treatment as a hazardous waste increase the operating costs of the technology.

The thesis “Abatement of siloxanes in sewage biogas: coupling adsorption and biological treatments” by Eric Santos Clotas, supervised by doctors Maria J. Martín (UdG), Alba Cabrera i Codony (UdG) and Joaquim Comas i Matas (UdG/ICRA), aims to investigate different technologies and also explore different activated carbons to eliminate siloxanes from biogas. In this work, different types of activated carbon both commercial and experimental from the valorization of waste from the food industry have been evaluated. Moreover, other technologies based in biological processes have also been applied such as biotrickling filtration and membrane bioreactors, with the objective of increasing the sustainability in the purification of biogas.