Hazardous odor markers from sewage wastewater: A step towards simultaneous assessment, dearomatization and removal

• GCMS has been specifically applied along with olfactometry in a Trickling Filter based Sewage Treatment Plant.
• Organosulphur based Hazardous Odour Markers are assessed by GCMS.
• Key odour markers for a Sewage Treatment Plant are: 1-propanethiol, ethylmethyl sufide and Disulfide, bis[1-(methylthio)ethiol].
• Odour Assessment is carried out by Panel Olfactometry.
• The time-variant odour concentration profiles go at par with the time variant Volatile Organo-Sulphur Compounds (GC/MS outputs).

Odor emissions from Sewage Treatment Plants (STP) may be hazardous and cause nuisance in the surrounding area. Odor is generated by the mixture of volatile organic compounds present in the sewage gas, leachate and leachate treatment systems, sewage sludge and waste materials.This research aimed to develop a quantitative Odor Assessment and Control Scheme (OACS) by simultaneous use of human sensors and liquid phase adsorption. Assessment of odor intensity was accomplished by the standard Sniffer Panel method of Olfactometry. Psychophysical laws were applied and validated to evaluate odor concentrations in the semi-solid, liquid and gas phases. Parameters of these laws were estimated by a robust nonlinear least square technique. It was observed that Beidler's equation on intensity–concentration relationship for sewage could be suitable for samples carrying intense odor from trickling filter based STP. The temporal reduction in odor concentration correlated well with the reduction in the concentration of the most hazardous volatile organo-sulfur compounds (VOSCs) such as n-Propyl Mercaptan (1-Propanethiol), Ethyl-Methyl Sulphide (Methylthio Ethane) and 3,6 Dimethyl 2,4,5,7-tetrathiooctane (bis 1-[{methylthio}ethyl] disulphide).