Development of a perimeter odor monitoring system for landfill sites

A need exists for instrumentation capable of continuous measurement of gas and odor emission from the perimeter of a landfill site. Current practice is to manually use a flame ionization detector. Instruments based on an array of MOS gas sensors were developed and placed on the perimeter of a landfill site, functioning as point monitoring systems, using methane as a surrogate for odor emission. The single-point instrument (SPEMMI) proved to be sensitive to methane, with the sensors showing a change in resistance of about 4% for a methane concentration of 50 ppm. On-site measurements showed that, while there was some sensitivity to temperature, it was possible to identify methane emission events. Data analysis techniques using a Savitsky-Golay second order filter show that event detection was possible. The system was operational in the field and was reliable. The use of complementary, n-type and p-type gas sensors, allowed discrimination of gas events from ambient temperature fluctuations.