Integrated system for monitoring of odor emissions from civil wastewater treatment plants.

The characterization and reduction of odor emissions represents an open debate among the scientific community. Odor nuisances are connected to a large number of chemical substances, mostly detectable at low concentration thresholds. Direct estimation of odor impacts through olfactometry is not always applicable, as this approach requires air sampling and a pool of trained panelists. Measuring the concentration of odorous substances (known as the analytical method) may be preferable in case a continuous monitoring of such impacts is needed. The objective of this research project is the design and development of an integrated odor emission monitoring system at the wastewater treatment plant (WWTP) in Castiglione Torinese, Italy, using an analytical approach. In this paper, the results of the preliminary stage are presented. The characterization of the emission sources was obtained by mean of three monitoring campaigns held between October 2017 and May 2018. A GC-MS analysis of air samples allowed the characterization of the main chemical species present onsite. A weather station was installed and entered into operation in September 2017. Results show that VOC is the only group of compounds that is always detectable on the site. Nevertheless, NH3 and H2S may, in some case, be present at considerable concentrations. If measurements are taken moving away from the emission source, concentrations decay rapidly to very low values (few ppb for VOC, below the detection limit for NH3 and H2S). In the view of the design and set up of the modelling chain, the characterization of emission sources results challenging, given the high number of sources on the site, with different shape and features. In addition, the estimate of odor emission flow is complicated by the low concentration values and the large surface of the sources. The design and features of the continuous monitoring system was defined according to the analysis of the preliminary results obtained from the monitoring campaigns. As a final result of this research project, CastiglioneTorinese’s WWTP will be equipped with a complete and integrated monitoring system of odor emissions, able to detect possible episodes of odor nuisances and immediately warn WWTP operators and environmental control agencies.