The application of electronic nose technology to environmental monitoring of water and wastewater treatment activities

An electronic nose instrument was evaluated for its ability to monitor liqu id wastewater samples, wastewater odor, and tainting compounds in water sup plies. Current methods for measuring odors are based on human sensory panel s (olfactometry) and used to determine 50% detection thresholds. Such metho ds are time consuming, labor intensive, and subject to large variation betw een analyses. An electronic nose, consisting of a nonspecific sensor array, could offer a more objective means of measuring odors emanating from water and wastewater. Monitoring of quiescent wastewater liquors from three trea tment works over an 8-month period showed that an electronic nose could dis tinguish between wastewater samples of different types and origins. Thresho ld odor numbers obtained from olfactometry analysis were correlated with el ectronic nose output for wastewater odors from 10 treatment works. Results suggested that no universal relationship exists between these parameters; h owever, a strong linear relationship can be produced for odor samples that are site or source specific. The electronic nose was also tested for its ab ility to screen raw and treated water supplies for tainting compounds. This aspect of the work demonstrated that low levels of organic pollutants can be detected by monitoring water samples with the nose.