Sampling and analysis of landfill gas / biogas, an overview

Lately it seems that the sampling and analysis of landfill gas / biogas is a popular topic among our customers.  When initially ask about the topic, I had an idea of what customers were trying to do, but didn’t really have a firm grasp on the topic.  As I dug deeper, I began to realize just how broad and complicated this topic actually was and no longer was I surprised customers were asking us for some guidance.

I was aware that gas analysis via GC was a primary aspect of monitoring landfills.  GC analysis of most or all fixed/permanent gases including CH4, CO2, N2, O2, CO and H2 was often mentioned by most customers.  I also knew that H2S and NH3 were typically monitored because of their negative health effects above certain concentrations and their unpleasant odors.

After a brief discussion of these gases, the next topic usually discussed was trace VOC's (Volatile Organic Compounds) collection/sampling and analysis. Unlike the fixed gases which are commonly collected in air cans and/or sample bags, trace VOC's are routinely collected onto thermal desorption tubes to concentrate the sample in order for the instrument/detector to be able to detect these trace levels.

Those two sampling/analysis were about the extent of what I knew. Only after talking with customers and reading more on the topic did I realize there were multiple other sampling/analysis performed associated with landfill gas / biogas.  These included mercaptans, siloxanes, non-methane hydrocarbons/organics, aromatics, alcohols, etc.  It seemed like the list of compounds could be quite extensive.

So how does one determine which analysis is needed? Usually the customer determines the list.  How does a customer determine the list?  If I understood correctly from the references I reviewed, it is determined by local, state and federal agencies based upon their regulations.  For landfills, it appears sampling/analysis requirements can be dictated by the size (acreage) of the site, the age of the landfill, and previous collected data.  For biogas, the starting material and the process (fermentation, digestion or other) usually dictates the compound list and/or method/analysis requirements.

For additional information, I found the following interesting and informative.  I hope you do too.

EPA landfill gas

Collection of Methods for Biogas

Guidance for Monitoring Trace Components in Landfill Gas