Disinfectants are commonly used in households, hospitals, in drug manufacturing, in food processing. With the ever-increasing antibiotic-resistance of microorganisms, it is crucial to rationally apply disinfectants in suitable concentrations, with proper active substance, as not all substances affect various organisms in the same way. Among the microorganisms that are particularly difficult to kill, there are bacteria producing spores - forms that have different structure and sensitivity to disinfectants than the vegetative forms. The aim of the study has been to examine the influence of frequently used disinfectant compounds upon the spores of bacteria of the Bacillus genus: B. cereus, B. mycoides, and B. subtilis. In the study of disinfectants the findings showed that the disinfectants with the best results against spores are: peracetic acid, hydrogen peroxide in concentrations of 30% as well as 5%, and Lysoformin 3000. The least efficient in fighting spores proved to be Isopropanol and Promanum N. Differentiation has been found to exist in the reaction of specific species to the preparation Rafasept, as B. subtilis occurred to be very sensitive to that compound, whereas Rafasept turned out to be ineffective in the case of B. mycoides and B. cereus.
The prevalence of heavy metals in wastewater is the cause of death of numerous organisms which take part in biological treatment of wastewater, that is why the aim of the study has been to asses the influence of cadmium and copper ions upon the microfauna of activated sludge. 5, 10, 50, and 100 mg/l of Cd2+ and Cu2+ were added into the samples of activated sludge and then, after 24 hours, the microscopic observations of activated sludge microfauna were carried out, and all changes concerning the amount of microfauna, functional groups, and species composition were determined. The results obtained allowed to find a high level of toxicity of Cd2+ and Cu2+ ions to activated sludge microfauna, which resulted in the changes in the value of the Sludge Biotic Index and classes of sludge, survivability of microfauna, and reduction in the number of taxonomic units. It was observed that Cu2+ ions are more toxic to activated sludge microfauna than Cd2+ ions in identical doses. Organisms sensitive to Cd2+ and Cu2+ ions have been found to be testate amoebae, Aspidisca sp. and Epistylis sp., as well as organisms relatively sensitive to tested metals, which turned out to be ciliates of Opercularia and Vorticella convalaria genera.