The purpose of the presented research is to analyse possible methods of thickening of the Microcystis aeruginosa (Kützing) Kützing cyanobacteria using the obtained concentrate as a biomass for the production of energy carriers and bio-logically valuable substances. Method of cyanobacteria thickening under the action of electric current and in the electric field, as well as the method of coagulation–flocculation and gravity thickening, was experimentally investigated in lab-scale conditions. Electrical methods didn't show positive results for the Microcystis aeruginosa thickening, despite the re-ports of their potential efficiency in a number of previous studies. The high efficiency of the method of coagulation–flocculation and gravity thickening of Microcystis aeruginosa suspensions was obtained. The optimum concentrations of industrial polymeric coagulants and flocculants for the thickening of Microcystis aeruginosa suspensions were defined in the range of about 10 ppm for the coagulants and about 1 ppm for the flocculants. Negative effect of the previous cavitational treatment of the diluted suspensions of Microcystis aeruginosa on the effectiveness of the coagulation–flocculation and gravitational thickening was confirmed experimentally. Hydrodynamic cavitation should be recommended to use after the thickening as the next step of processing of concentrated suspensions of Microcystis aeruginosa to achieve maximum extraction of energy carriers and biologically valuable substances.

This article presents research on the structure of energy mixes and the dependence on imports of the EU-27 member states, with a particular emphasis on Poland. During the conducted research, a spatial information system was used. GIS tools made it possible to build layers presenting information based on the countries’ energy mix, the level of dependence on the import of this fuel, and the share of the Russian Federation in fuel imports. It was also examined whether the level of dependence on imports from Russia was dependent on the geographical location. Since it has been shown that the share of Russian fuel is significant in the energy mixes of many member states, and that security does not depend solely on import dependence, an energy security assessment measure has been created (SES). As the level of security consists of many factors, assessing each of them separately is very difficult and unclear. Therefore, in order to simplify this analysis, it was necessary to determine one indicator that would take into account all the factors influencing the level of energy security. Poland is privileged in terms of access to fossil fuels due to its rich coal deposits; however, the potential of this fuel is not used, which is also indicated by the level of the SES measure. In the case of Poland, SES amounts to less than 16% and is almost three times lower than the EU-27 average. The indicator made it possible to indicate not only those factors that positively affect the level of energy security but also those that adversely affect it. It also enabled the identification of possible remedial measures.