Dispersion Modeling and Assessment of Volatile Organic Compound Emissions From a Municipal Wastewater Treatment Plant

Abstract

This study presents the dispersion modeling and assessment of total volatile organic compounds (TVOC) emissions from a municipal wastewater treatment plant in Saudi Arabia. The study uses the AERMOD dispersion model to predict the ground-level atmospheric TVOC emissions over 1-h, 8-h, 24-h, and annual periods under average and peak flow-rate scenarios. The effects of winter and summer seasons on TVOC dispersion were also analyzed by generating seasonal dispersion maps. The significant findings indicate that maximum TVOC concentrations are confined within the Dhahran North Sewage Treatment Plant (NSTP) area, attributed to low release heights from aeration and settling tanks. TVOC concentrations during the summer were approximately 6.8% higher than the annual average due to lower wind speeds, while winter winds enhanced dispersion, resulting in an 8.7% decrease in TVOC concentrations. The study shows that TVOC levels decrease with distance from the source, following linear and logarithmic patterns. Comparison with wastewater treatment plants in other regions demonstrates that Dhahran NSTP has lower TVOC concentrations, highlighting the influence of influent characteristics on emission levels. The strong correlation between influent flowrate and TVOC concentrations reinforces the consistency of the findings with similar facilities. The study findings indicate that the predicted atmospheric dispersion of TVOC from Dhahran NSTP may not pose a health risk to treatment plant employees and the public residing within the selected receptor domain. This supports the efficacy of the implemented air quality management practices.