“Vortexing” Away Hydrogen Sulfide – Reducing H2S Concentrations
- Troy Maciaszek PE - Hazen and Sawyer
- Guy Schmoltze - Joint Municipal Water & Sewer Commission
As the levels of hydrogen sulfide (H2S) rise, there is a direct increase to a system’s operation and maintenance costs, regulatory impacts, environmental issues and safety concerns. There are several ways to control the hydrogen sulfide in a system, but you must first understand the physical characteristics of the wastewater. Joint Municipal Water & Sewer Commission (JMWSC) contracted with Hazen and Sawyer (Hazen) to assess the extent of odors and corrosion potential within a portion of the JMWSC’s collection system. This project was divided into two phases with the first phase evaluating the wastewater and providing recommendations. The second phase was the implementation of the recommendations to achieve acceptable levels of hydrogen sulfide within the system.
JMWSC authorized Hazen to evaluate the odor and corrosion potential of the sewer collection system from several areas of interest including the Old Barnwell Pump Station. Hazen conducted a physical evaluation of the wastewater that included both liquid and gas samples. It was found that the H2S concentrations were the highest at the Old Barnwell Pump Station with average measurements of 136.4 ppm and peak values of 256.00 ppm. The H2S concentration is a main contributor to corrosion, so it was determined that steps needed to be taken to reduce the H2S at this point in the system.
An analysis was performed to determine the best, and most feasible, solution to reducing the H2S at the Old Barnwell Pump Station. An evaluation of liquid phase treatment, ventilation, and wet well characteristics were studied to recommend the best alternative for further study and design. Ultimately, it was determined that moving existing liquid phase treatment to an upstream pump station and modifying the wet well flow would provide the best solution.
During the second phase of the project a review of the wet well flow patterns were completed to determine what options were available to reduce the turbulence created by an existing wet well trough. A Vortex unit was evaluated and determined to be the best option to modify the turbulence of the wet well flow. This system was designed, permitted, constructed and produced immediate, measurable results. The construction of the project was completed in August of 2016 with average temperatures in the mid-90’s. The average H2S concentration during the time period immediately following construction was 24.7 ppm producing a reduction of over 80% of the H2S. Ventilation was suggested as an alternative to the construction contract and the system will continue to be monitored through the winter months to see if the ventilation system is necessary to further reduce the H2S levels.
The project required planning, coordination, and communication between the Utility Engineering and Operations Staff, Consultant, and Vortex Manufacturer. The presentation will focus on the study needed to identify the characteristic of the wastewater, the analysis of options to reduce H2S corrosion, the construction of the project, and the measureable reduction of the H2S concentrations.
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