A large Midwest vegetable canning processor has a waste treatment system that treats 100,000 gpd (380 m 3 /day). The system consists of an aeration basin, anaerobic settling lagoon, and sludge lagoons.
The system has been operating for many years without chemical treatment. The customer had actively sought odor control advice from several companies to eliminate odor-related problems. Several treatments, such as ferric chloride, were considered.
Odors from the lagoons led to complaints from neighbors as far as a half mile away. Most of the odors smelled like rotten eggs with an underlying odor associated with organic decay. In addition, employees near lagoons complained of eye burning and tearing.
Because the sludge was used on farm land, the use of heavy metal salts for odor control was not practical. The use of oxidizing agents, such as potassium permanganate, and hydrogen peroxide, were also considered, but because the organic level in the plant’s wastewater was high, these were not cost effective.
After surveying the system, Veolia recommended a ProSweet Odor Control program. To immediately attack the H2S problem, a ProSweet OC series product designed to prevent the formation of H2S was fed into the system at a point to ensure good product mixing. Another ProSweet OC product, which influences the bacteria to produce byproducts other than H2S, was fed at a point before entering the lagoons in order to permit the enzyme to interact with the anaerobic bacteria.
After beginning the ProSweet OC feed, the H2S odor disappeared. The second ProSweet OC product, fed at maintenance dosage, kept the H2S below detectable levels. Neighbor complaints ceased, and employees can now work in the vicinity of lagoons without eye irritation. Sludge can also continue to be used on farm land.