The biogas produced from wastewater digesters possesses desirable energy value and its use assists initiatives to decrease global warming. The production of biogas from municipal solid waste and wastewater sludge has increased in the past years and many sewage treatment plants are collecting and using their biogas mixtures to obtain energy. However, in order to be used as a high-quality fuel, biogas needs to undertake a process of upgrading, to remove the undesirable volatile compounds such as siloxanes [1] that negatively affect the energy recovery systems. Sources of siloxanes are substantial and increasing, as they have many applications in personal- care products, pharmaceuticals or lubricants. The most volatile siloxanes disperse into the atmosphere, but less volatile compounds, like octamethylcyclotetrasiloxane (D4), remain accumulated in the sewage sludge and, given the high temperatures in the digesters, the biogases are generated containing siloxanes. During the combustion of biogas, siloxanes are converted into silica, leading to the abrasion of engine parts or the build-up of silica layers that inhibit essential heat conduction or lubrication [2].
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