International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

A comprehensive study of the air condition in urban areas was conducted, based on lidar monitoring. The subject of monitoring are two districts of Sofia the capital of the R.Bulgaria. The time period of the study is May-June 2020 and coincides with the introduced quarantine period in connection with the COVID-19 pandemic. The study includes lidar monitoring of the selected urban areas taking into account the mass concentration of particulate matter (PM). The method is combined with in situ sampling taking into account also the size control in μm – PM2.5 and PM10. The data are compared with those from the indications for the period of the licensed laboratories of the Ministry of Environment and Water and the Civil Network. A physicochemical study of the phase composition, structure and dispersion of the collected PM was performed by the methods of powder X-ray diffraction and Mössbauer spectroscopy. Predominant pollen and spore contamination was reported using Cascad Impactor measurements. Most part, the PMs studied show a conglomerate of several particles.

Acid mine drainage waters polluted by iron, several non-ferrous metals (mainly copper, zinc and cobalt) and sulphates as the main pollutants were efficiently treated by a lab-scale passive system consisting of an alkaline limestone drain and a permeable reactive multibarrier connected in a series. The multibarrier was filled by a mixture of solid biodegradable organic substrates (mainly of plant biomass) and was inhabited by different metabolically connected anaerobic microorganisms (mainly different heterotrophs including some iron-reducing and sulphate-reducing bacteria). The effluents from this system were rich in soluble organic compounds and were treated in a microbial fuel cell in which consortium of electrochemically active microorganisms used these compounds as donors of electrons for electricity generation.

Biotechnologies could supply inexpensive, environment friendly and effective materials for new nonstandard and concurrent solutions. The present work’s focus was on acquiring new physical data for application in electronics and medicine of biogenic materials obtained due to the metabolism in laboratory conditions of iron-oxidizing bacteria from the genus Leptothrix. Powders and coatings on glass samples were under investigation. XRD and Raman Spectroscopy analysis of the data collected show that the Fe²⁺-depending from the growth media could transformed into Fe³⁺ or Fe^2.5+ in the form of two types of oxides/hydroxides such as magnetite (Fe₃O₄) and lepidocrocite (ɣ-FeOOH), all with nanostructured morphology. Biotechnology for obtaining one biogenic iron phosphate hydroxide (ferrian giniite) – (Fe₅(PO₄)₄(OH)₃.2H₂O) was also developed. The ferrian magnetic material is dispersed in the walls of biogenic tubular structures.
The average particle’s size and crystalline structures of bio-products were investigated. Results based on PPMS measurements on the magnetic properties were reported. The new biogenic materials showed superparamagnetic behaviour and high sensitivity to electromagnetic radiation and have real potential for application in electronic and information technologies.