Terpenes and Siloxanes

Biogas and biomethane must reach consistently high standards. Yet, as they’re derived from organic waste, they contain impurities. Desotec has the solution. Our filters handle a range of contaminants, including two of the most common: siloxanes and terpenes.

Siloxanes are volatile liquid compounds that do not biodegrade easily. They’re used in cosmetics, deodorants, water repellents, food additives, and soaps, so are often found in the biogas stream produced at wastewater treatment plants (WWTPs).

Terpenes usually come from the fermentation of green waste, including fruit, vegetables, and agricultural by-products. They may also be derived biosynthetically from isoprene for use as fragrances in cosmetics.

Every company wants to protect its machinery and equipment, reducing maintenance costs and repair bills. Yet, siloxanes give rise to abrasive silica (sand-like) deposits when combusted in machinery such as combined heat and power engines (CHP). If these sandy deposits exceed the manufacturer’s stated limits, they reduce the lifespan of this important and expensive equipment.

Desotec offers a simple solution. Our filters purify the biogas stream from siloxanes, so it can be fed into a CHP to produce low-carbon energy. As other compounds, such as hydrogen sulfide (H₂S), are likely to be present in the biogas stream, multiple filters may be placed in series.

We all love the smell of Christmas trees, which are produced by natural terpenes. In high concentrations, though, these compounds are an odour nuisance for workers and neighbours. So, it’s essential to purify biogas from terpenes to keep the air smelling fresh.

Plus, removing terpenes is necessary to protect the membranes used to upgrade biogas into biomethane and prevent gaskets and piping systems from corrosion.

Desotec is here to help. Our mobile activated carbon filters adsorb terpenes and siloxanes, allowing biogas to be upgraded into biomethane. The latter can then be injected into the national grid or converted into compressed natural gas (Bio-CNG) or liquified natural gas (Bio-LNG) for use as transport fuel.

Legislation governing air quality (including emissions of volatile organic compounds (VOCs), terpenes, and siloxanes) is becoming increasingly stringent. Desotec filters are modular, so they can easily be adapted to help you reach lower limits, thus future-proofing your company.

Odour control tends to be governed at the country level. The Nordics have especially strict regulations, but other countries are following suit.

Manufacturers set guidelines for using their machinery, including CHP engines. If you exceed their stated limits for terpenes and siloxanes, you will invalidate your warranty. By installing Desotec filters, you extend the lifespan of your equipment and cut your costs.