Dispersion Modeling of Odor Emissions from Area Sources in a Municipal Wastewater Treatment Plant

Wastewater treatment plants (WWTPs) generate significant emissions of gaseous substances, such as H2S, NH3, and VOCs, which cause discomfort and pose health risks to residents in surrounding areas. The objective of this study was to estimate pollutant concentrations under various scenarios through a mathematical modeling of the pollutant dispersion in the surrounding air using the AERMOD View software platform, version 11.2.0. In this study, four mathematical models with two different scenarios were conducted to illustrate the odor concentrations both on site and in nearby areas under the most unfavorable weather conditions. The “1st Highest Values” and “98th Percentile” metrics were used to represent the peak concentrations and to exclude the 2% of conditions with the worst-case dispersion, respectively. In the first scenario, under normal operating conditions with all treatment equipment functioning, the maximum on-site odor concentration was estimated at 36.8 ouE/m3 using the 1st highest value function, and it was 20.4 ouE/m3 using the 98th percentile function. The second scenario considered all emission sources, with the grease collection system of the de-sanding/grease separation Unit Line 1 and the sludge collection system of the primary settling decanter (Unit 4) out of service. In this case, the maximum on-site odor concentration reached 749 ouE/m3 over 98% of a one-year period and 956.5 ouE/m3 using the 1st highest value function. These findings underscore the necessity for ongoing monitoring, strict adherence to environmental regulations, and stakeholder engagement to improve mitigation techniques and foster community trust in environmental management. Regular inspections are essential to ensure that all equipment operates within normal parameters, supporting both regulatory compliance and improved operational efficiency, including the control of odor emissions.