Odour emission from primary settling tanks after air-tightening

The purpose of the present article was to determine odour emission rate from primary settling tanks after hermetisation. The paper presents the results of the research on odour emission from four settling tanks, covered with self-supporting aluminium domes with a diameter of 52 meters, located on urban wastewater treatment plants, with the planned flow capacity equal to 200 000 m³/day. Altogether, the olfactometry analysis of 189 samples of polluted air pulled from the domes with the use of an air blower which has efficiency of 12 000 m³/h was conducted. The results of odour concentration measurements were in a range of approximately 10 800 to 763 600 ou_E/m³. Average odour emission rate was equal to 102 ou_E/(s · m²). The obtained value is much higher than the literature data, available for non-hermetised settlers only. This rate enables better estimation of the odour stream that has to be deodorised after sealing the settling tanks.