THE VORTEX DROP STRUCTURE IMPLEMENTATION FOR ODOR AND CORROSOIN CONTROL

Hydrogen sulfide gas emissions cause extensive corrosion and odor problems in wastewater conveyance and treatment systems. A significant source of these emissions is from drop structures such as interceptor drop maintenance holes, forcemain discharges, joint structures, and wet well drops in sewer pumping stations. The Vortex Drop Structure (VDS), invented by Eugene Natarius, is an effective energy dissipater and aerator, which considerably improves the drop structure. It dissipates the flow energy and aerates the wastewater, preventing emission of odorous gases, oxidizing the hydrogen sulfides, and protecting the drop structure from corrosion and abrasive wear.Metropolitan Council Environmental Services, a regional public agency serving the Minneapolis/St. Paul area, successfully implements the VDS. Four installed VDS have been working on main interceptors with no odor complains from the public. The cost of chemical feed for odor control has been significantly reduced, and the structures are virtually maintenance-free. Additional VDS installations are in progress at a pumping station wet well, and on a forcemain discharge.Testing to measure VDS effectiveness was performed at two installations. The analysis of multiple wastewater samples taken simultaneously upstream and downstream of the Vortex Drop Structures shows a significant decrease of dissolved hydrogen sulfides and a sharp rise in the dissolved oxygen concentrations downstream of the structures. The results of air quality monitoring around VDS installations indicate a strong effectiveness. Odor complaints from adjacent homeowners have virtually disappeared.