This article presents microbiological air pollution around wastewater treatment plants in Słupca, Kostrzyń, and Września, and the Complex Wastewater Treatment and Wastes Composting Plant in Grodzisk Mazowiecki, Poland. The samples of air were collected using the sedimentation and aspiration methods. The largest group of microorganisms in the monitored air were psychrophilic and mesophilic bacteria and microscopic fungi. The number of psychrophilic bacteria ranged from 78 to 225,000 CFU/m³, the number of mesophilic bacteria varied in the range from 0 to 195,000 CFU/m³ and the fungi – from 0 to 65,700 CFU/m³ of air. The amount of other bacteria (Staphylococcus, Pseudomonas fluorescens, and coliforms) ranged from 0 to 87,500 CFU/m³.
A great number of bacteria and fungi has been detected near sewage aeration tanks, places of sludge disposal, and grit chambers. The interpretation of the results has been conducted according to the Polish Standards, which classify the degree of air pollution in reference to the number of microflora in the air. A change in air pollution has been noted depending on the season and climatic conditions (wind strength in particular). Research has shown that coliform bacteria, although not included in the Polish Standard, constitutes a good indicator of microorganisms’ emission from sewage into the air.