Hydrogen sulfide and odor control in Izmir Bay

The city of Izmir on the Aegean Sea shoreline is suffering from rotten odor s emitted by anoxic river mouths. Anaerobic conditions in the shallowest po rtion of Izmir Bay due to industrial and domestic wastewaters as well as eu trophication products in this very calm part of the Bay are responsible for this. The inner section of the Bay is becoming shallower with sediments ri ch in organic matter. Aerobic digestion of organic pollutants is limited by the oxygen input and the warm climate leads to an optimal medium for anaer obic processes when anoxic conditions take over. Anaerobic digestion produc ts are odorous gases among which H2S with a characteristic pungent odor is most effective in this case. Sulfur containing gases are formed from sulfid es and sulfates in the sediment-water interface and are released into the a ir. Airborne H2S concentrations are variable as they depend on factors such as high atmospheric diffusion coefficients under changing wind direction a nd speed, as well as variable such as water depths, organic loadings from r ivers, air and water temperatures, sulfate concentrations in sediment and w ater phases, pH, and Eh. This study aimed to control noxious smells by inhibiting the anaerobic sulf ate-reducing bacteria at the sediment surface. To achieve this aim, pH of t he sediment-water interface was increased by spreading hydrated lime. Succe ssful lime doses were investigated in laboratory models first and were then tested and applied in the estuary and downstream segment of one of the cre eks. Rates of H2S gas emissions and aqueous H2S levels were measured. It wa s noted that waterborne H2S levels at river mouths were reduced. Odor contr ol efficiencies of 80-96% even after 10 days of lime addition in the field experiments were obtained. Therefore, the results of this study indicated t hat lime application to the sediment surface is a recommended method in odo r control programs.