The team began by performing onsite wastewater treatability tests to verify the oxidation concept and determine design parameters. They directed a controlled flow of the facility’s wastewater to a bench-scale testing area, where the effluent was fed into buckets and tubs of various sizes with air diffusers installed in them. They then tested different combinations of air flow, retention time and tank size to find the optimal configuration to completely aerate and oxidize the hydrogen sulfides. The results helped CDM Smith size the full-scale oxidation tank so that it was not too small (where sulfides would not oxidize sufficiently) or too big (which would add costs for Bel Brands).
The constructed stainless-steel, 81,250-gallon oxidation tank processes up to 374,000 gallons of cheese processing water per day. Requiring less than 5 hours of retention time to fully eliminate the odors before discharging the effluent, the system can handle influent hydrogen sulfide concentrations as high as 128 milligrams per liter (mg/L). The tank features a fine bubble diffuser system to provide complete mixing and a maximum dissolved oxygen concentration of about 8 mg/L at 25 degrees Celsius. Three positive displacement blowers adjacent to the tank provide the air to the diffusers.
The new oxidation system’s smart design enabled Bel Brands to avoid new chemical storage and feeding, as well as offsite waste disposal, minimizing long-term operating costs. Under an aggressive deadline, CDM Smith’s design-build team not only met the schedule, but their solution helped Bel Brands meet its treatment objective. The hydrogen sulfide odors were fully eliminated from the plant’s discharged effluent, allowing Bel Brands to maintain its strong commitment to environmental and community responsibility.