Emissions Comparison of Natural Gas Usage and Digester Gas Usage in Biosolids Drying

Municipal wastewater contains a wide variety of volatile organic compounds that are released during throughout the treatment train. In common practice, instead of natural gas, digester gas is used for economical reasons. This practice raises concern whether this adds to the VOC emissions that could subject the plant to Hazardous Air Pollution (HAP) regulations. The current research was conducted to identify differences between natural gas and digester gas in the Regenerative Thermal Oxidizer (RTO) when the Drum Drying System (DDS) was operated. The Morris Forman Water Quality Treatment Center (MFWQTC) in Louisville, Kentucky was the experiment site. The DDS was run in two cases: fueled by digester gas and fueled by natural gas. Obtained samples were analyzed at the University of Louisville. The data from these two test cases showed no significant RTO emission differences between fuels. Therefore, it is observed that the use of digester gas instead of natural gas is economical without emitting additional harmful emissions.