Siloxanes Complicate Biogas Picture, But Solutions are at Hand

September 8th, 2010 by Tina Casey

Perhaps you’ve heard of siloxanes — those ubiquitous chemicals found in hair care products, make-up, deodorant, food additives, soaps, textiles, lubricants, paints – oh heck, the list goes on and on. The problem is, siloxanes end up in biogas recovered from landfills, industrial operations and sewage treatment plants. If not removed they can end up causing severe damage to equipment.

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In recent years the problem has also migrated over to the agricultural sector, which could complicate the federal government’s efforts to promote dairy farm biogas and other agricultural biogas recovery through its Agstar program. Fortunately, new gas scrubbing technologies have been running neck and neck with the siloxane problem, but it does indicate that in the future, manufacturers – and consumers – will have to take the impacts on the waste-and-recovery stream into consideration when formulating and using new products.

The Problem With Siloxanes

Siloxanes are in the class of organic compounds with carb0n-silicon bonds, and therein lies a clue to their destructiveness. Silicon is the most common material in the earth’s crust, in the form of sand and quartz. When gas containing siloxanes gets into machinery, the siloxanes can build up into a glasslike material that blocks turbines and grinds down metal parts. The problem is not new, though in recent years it has increased as new products enter the market.

Siloxanes in Agricultural Biogas

One thing that does appear to be new is the relatively sudden and rapidly growing appearance of siloxanes in biogas from the agricultural sector. CleanTechnica spoke with Tim Robinson, COO of Applied Filter Technology, Inc., about the trend. According to Robinson, the problem could derive from new products introduced in cattle and dairy operations, for example in the use of new fly repellents containing siloxanes. Applied Filter got its start with the invention of a graphite molecular sieve designed to prevent siloxanes from blocking turbines at a large sewage treatment plant about 14 years ago, and since then it has developed additional patented technologies related to biogas and wastewater systems of all sizes.

Growth of Biogas Markets

Biogas is still flared off or otherwise wasted in many agricultural operations, but that is rapidly changing. Aside from the federal government’s effort to promote biogas recovery through Agstar, agribusiness giants such as Cargill are dipping their toes in the biogas market in pursuit of big profits. Somewhere down the line that could result in some interesting new alliances between industry, consumer and environmental groups, with the aim of reducing or eliminating potential contaminants from agricultural use, in order to ensure that agricultural biogas recovery remains cost-effective and profitable.

Image: Cow by C, S, M and M on flickr.com.

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Tags: Agriculture, AgStar Program, Applied Filter Technology, Biogas, dairy farms, siloxanes

About the Author

Tina Casey Tina Casey specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Tina’s articles are reposted frequently on Reuters, Scientific American, and many other sites. Views expressed are her own. Follow her on Twitter @TinaMCasey and Google+.