Odor Determination at Wastewater Collection Systems: Olfactometry versus H₂S Analyses

Abstract

Abstract H 2 S is usually the main indicator parameter to assess when nuisance odors arise in wastewater handling systems. However, sampling and measurement of H 2 S need to be made with utmost care and analytical methods are neither easy nor cheap. Although Jerome meters from Arizona Instruments are used in some parts of the world, the cost and difficulty of measuring H 2 S in odorous gases is a general problem. It should also be kept in mind that a simple linear relationship between H 2 S concentrations and odor perception by the public is not available, especially in complex odorous gas mixtures. This leads to the conclusion that measuring the H 2 S alone is neither easy nor accurate in describing and resolving public complaints due to odors from wastewater collection and treatment systems. In this study, data for odors and H 2 S measurements from two pumping stations of the wastewater collection system of Çesme, Izmir, Turkey are evaluated. Concentrations of H 2 S were measured with chemical methods. Results indicated concentrations several orders of magnitude above the odor threshold level, which is generally accepted as 0.1 μg/m 3 for pure H 2 S in air. The statistical relationships between analytical and sensory odor data were established. Correlations indicated power law relationships between odor and H 2 S concentrations ( R 2 between 0.88–0.92). Steven's law between the intensity of human perception and concentration of stimulants is obeyed.