No abstract

In aerobic conditions, many of microorganisms cause decomposition of saturated hydrocarbons. Little publications are available relative to anaerobic transformation of these compounds, which provides substantial сapiltal saving for waste water treatment. At the same time, cultures found among aerobic decomposers of petroleum products are characterized by the ability to use elements with variable valence as terminal electron acceptors in oxidation of organic substances. Their ability to decompose aliphatic hydrocarbons helps to identify some of them.Purpose: studying the ability of a selected association of immobilized bacteria on a fibrous carrier to utilize sulfate as a terminal electron acceptor for toluene oxidation.Methodology/approach: Analytical summarizing of results, literature review, laboratory research based on standard and modern up-to-date methodologies with the use of modern analytical equipment.Findings: The availability of using microorganism selection is shown for expanding the range of polluting strippants in biological purification; the main directions are determined for the process intensification by immobilization of active sludge on a fibrous carrier. The ability of microorganisms to oxidize toluene under oxygen-free (anaerobic) conditions is studied in the laboratory conditions.Research implications: monoaromatic hydrocarbons, toluene, in particular, can be changed by selected associations of decomposers using terminal electron acceptors in oxidation of nitrates and sulfates.

Introduction. The novelty of the research is driven by the growing environmental contamination with anthropogenic substances, and in the course of accidents and emergency situations, as well as the need to develop the most advanced methods of their elimination. More intensive application of selected micro-organisms, capable of using variable valency chemicals as terminal acceptors, can help to treat wastewater from organic and mineral pollutants. Materials and methods. The co-authors have performed a review of literature and used analytical equipment to conduct laboratory researches according to standard and advanced methodologies. Results. The principal results include the restructuring of the treatment facilities operated by Autodetail Open Joint Stock Company. The restructuring consisted in the feeding process change in the currently used biological tower for the feeding to be performed with the help of the fiber carrier and immobilized association of oil oxidizing microorganisms. The association was obtained in the course of earlier laboratory researches. The most active nitrogen-gathering and oil oxidizing cultures, including Rhodococcus erythropoltis, Pseudomonas fluorescens, Arthrobacter tumescens, Pseudomonas rathonis, Azotobacter chroococcum, taken in equal parts, helped to develop a bio-product designated for the decomposition of oil and its components in the aquatic environment. This bio-product was immobilized in respect of the feeding to be performed with the help of the fiber carrier and loaded into the production company’s biological tower which is part of idle wastewater treatment facilities. Conclusions. In the course of the work performed at the first stage, special cultures were selected for the treatment of water from hydrocarbons of anthropogenic origin. These cultures had nitrogen-fixing properties needed to reduce secondary anthropogenic pollution of the water body. At the second stage, water treatment facilities of Autodetail Open Joint Stock Company were restructured and operation-related results were obtained. They enabled the researchers to make a statement that the biological transformation of pollutions was efficiently applicable to the suspended matter — 99.7 %; oil products — 98.3 %; COD — 89.2 %; nitrogen of ammonium salts — 77.9 %; mineral phosphorus — 53.3 %. Acknowledgements: The co-authors would like to express gratitude to all reviewers and the writing team for the publication of this article.

The article presents the results of studies on decomposition of petroleum products, on the example of diesel fuel, the investigation having been carried out in a bioreactor with loading of immobilized microorganisms specially selected and adapted to the destruction of hydrocarbons. In the course of the investigation, 25 micro-organism culture strains were isolated from crude oil by selection, the strains had different destructive activity relative to hydrocarbons of the paraffin fraction of diesel fuel and nitrogen-fixing ability. Further, selection was carried out along with oxidation of hydrocarbons and according to the ability of microorganisms to nitrogen fixation. Such microorganisms during oxidation of hydrocarbons will allow reducing the content of biogens in purified water. Part of the microorganisms was identified and the nitrogenase activity of pseudomonades was investigated. When growing on diesel hydrocarbons in a bioreactor, nitrogen assimilation is most active in Rhodococcus erythopoltis R-2 culture and equals 10.52 nmol C2H4/mg protein per hour. The maximum nitrogenase activity has the association of bioreactor destructive cultures obtained by the authors, which, when growing on diesel oil products is 23.7 nmol C2H4/mg protein per hour, which is 2.3 times higher than the nitrogen-fixing capacity of Rhodococcus erythropoltis R-2. There was studied the rate of hydrocarbon degradation, оn the seventh day of cultivation, the degradation of paraffinic hydrocarbons in nitrogen-free media is 68%, whereas in the presence of ammonium nitrogen it reached - 87 %. These investigations have determined the ability of isolated cultures of oil-oxidizing bacteria to use hydrocarbons under atmospheric nitrogen assimilation conditions.