Sulfide Elimination Program Solves Odor & Corrosion Issues

The Challenge

A Midwestern Ethanol facility was experiencing severe odor issues due to Hydrogen Sulfide (H₂S), resulting in higher than acceptable corrosion rates throughout their system. There were also concerns about the potential for employee health & safety risks associated with the elevated levels of H₂S.

Veolia Water Technologies was brought in to fully evaluate the situation and to determine the best solution for alleviating the problem. In order to ensure continuous and reliable performance of the odor control program, and minimize the downstream impacts on the local POTW Headworks, Veolia was also asked to design and integrate a customized automation and control platform into the treatment program.

 

The Solution

After a thorough survey of the plant which involved detailed testing and trending H₂S levels to determine the highest priority areas to address, a 2 product odor control approach was implemented. At the heart of the treatment solution were Veolia's Hydrex™ 67808 (Reagent) and Hydrex™ 9561 (Oxidizing Agent) technologies. When applied together and controlled properly, the Hydrex Sulfide Elimination System program instantly produces powerful hydroxyl free radicals which oxidizes any sulfides in solution in less than 3 minutes. In oxidized form, the sulfides pose no threat to contribute to the formation of H₂S.

 

Process Description

The Hydrex™ 67808 lean chelated iron (Fe3) complex is dosed into a manifold or pipe, as shown below, where it reacts with hydrogen sulfide and creates elemental sulfur, thus losing an electron, resulting in a rich (Fe2) molecule. When an oxygen source (Hydrex™ 9562) is introduced it regenerates the Hydrex™ 67808 chelated iron molecule and allows it to react with additional hydrogen sulfide. This redox process is created repeatedly until there is no presence of hydrogen sulfide available.

 

Results

Veolia implemented the Hydrex Sulfide Elimination System on May 9, 2022, and immediately eliminated all odor complaints and H₂S concerns. The client site remains at ZERO ppm H₂S and the downstream municipal POTW headworks have seen reduced influent H₂S levels at or around 10 ppm. The financial savings as a result of eliminating H2S-induced corrosion is in the process of being determined, but the elimination of health and safety concerns more than outweighs any other factor.

The charts below were generated by the HSES automated control system. They show the immediate impact on the client’s system, as well as the downstream impact on the City’s POTW Headworks.