The study looked at controlling odors at an activated sludge plant. While trickling filters and aerobic ponds often have odor issues due to overloading, activated sludge plants are usually odor-free. However, an overloaded activated sludge plant treating wastewater from a yeast production plant in Italy caused bad smells for over 6 months. This shows that overloaded activated sludge plants can lead to poor effluent quality and nuisance odors.