Evaluation of hydrogen sulfide emission control technology in a high-strength wastewater treatment application

Wastewater treatment plants, such as the Cedar Rapids Water Pollution Control Facility (CRWPCF), often struggle with hydrogen sulfide (H₂S) emission control. When high enough concentrations are inhaled, H₂S presents a danger to human health and can even claim lives. Here, we discuss a H₂S ambient air monitoring project, which captured ambient concentration reductions following emission control upgrades at CRWPCF. Additionally, we report that when coupled with air dispersion modeling, a more comprehensive evaluation of community exposure to H₂S was achieved. Bertram Township, Cheyenne Dog Park, Don Murphy Lake Park, and Indian Creek Nature Center were all identified as locations of interest where potential citizen exposure could occur. Through scenario investigation, the American Meteorological Society-Environmental Protection Agency Regulatory Model showed that Cheyenne Dog Park and Don Murphy Lake Park both experienced more health threshold exceedances than Bertram Township and the ambient monitoring site prior to the emission control upgrades, indicating the station may not have captured the highest ambient concentrations occurring in the community. Out of all locations evaluated, Don Murphy Lake Park consistently experienced the greatest number of hourly values above the low odor threshold of 1 ppb, mean odor threshold of 8 ppb, and above the health threshold of 30 ppb. Additionally, Indian Creek Nature Center continued to experience heath threshold exceedances after the emission control construction. We conclude that if an equipment failure were to result in excess H₂S emissions in the future, Indian Creek Nature Center would likely experience the highest number of hours exceeding 30 ppb.