Beyond H2S: Applying Gas Chromatography to Characterise Sewer Odour Emissions

Management and control of odour emissions from sewers offers many challenges. While abatement based upon H2S has addressed many sewer odour issues, a wide range of compounds are emitted from sewers that may not be efficiently removed by existing odour abatement processes, or negatively impact performance. Towards providing insight into non-H2S sewer emissions, a long term monitoring program was conducted for several sewers located in Sydney (Australia) to identify key compounds of interest. A range of sewer sites were studied, including sites with residential and commercial wastewater, sites downstream of sewer structures, sites with upstream chemical addition to control H2S, and sites with upstream discharge of industrial wastewater. The monitoring program included the application of gas chromatography based analytical techniques to analyse two families of odorous compounds, namely volatile organic compounds (VOCs) and volatile sulfur compounds. Odorants were identified using combined gas chromatography and olfactory analysis. Independent of the type of wastewater being transported on the site, a large number of non-odorous VOCs were detected at all sites. Supplementing conventional VOC analysis techniques with dedicated sulfur and nitrogen analysis techniques would enable enhanced identification, prioritisation, and tracking of key sewer odorants, and provide a more robust picture of the key odorants present in the sewer gases.