Metodologiczne aspekty badania substancji odorowych w otoczeniu oczyszczalni ścieków

Problems of emission of odorants in Poland are not regulated administratively, because there are no regulations to appropriate law records. Still, there is a norm that defines method of measurement, however using it according to polish law is voluntary. The present study is based on the results of measurements carried out at a sewage treatment plant and around that object. Studies were performed using so called expert method that allows practical assessment of nuisance and impact of odorous substances on the environment. Measurements of odorants contents at mechanical-biological sewage treatment plant and in its vicinity were carried out in the years 2013–2014. Measurements of odorants were taken on average 3 times per month and each time in 10 characteristic points, taking into account the basic technological and environmental processes (Fig. 1). Assessment of odour nuisance was made by group of 4 experts with relevant experience and proven sensory sensitivity. Individual parameters of odour intensity measurements in time were rated by 4 experts (A, B, C, D) according to the following odour scale: 0 – imperceptible, 1 – weak, 2 – distinct, 3 – strong. Particular odorous nuisance emitted from the area of sewage treatment was observed at a distance of about 300 m. Nuisance observed at the distance of approximately 500–600 meters from the main sources of emissions was much smaller. Sporadic air pollution with odorous substances are also found in the distance of 900 m in developed agriculturally area and near existing residential development. Thus, nuisance zone of examined sewage treatment plant should be 900 m (Fig. 1). Results of this study and public consultation prove that all nuisance related to the operation of sewage treatment plant depend on composition of odorants in vicinity of the plant, their intensity and frequency of appearing during year. Those factors strongly correlate with directions and wind speed (very variable in the studied area), temperature and geomorphological factors. Very beneficial has here tree coverage of the area. Research odour intensity with the use of expert method should be supplemented with olfactometric measurements.