Biological Cleaning of Soil and Reservoirs from Oil Products

The production of oil and gas condensate invariably involves environmental hazards: water and soil contamination due to miscellaneous breakdowns of technological equipment and pipeline damage. Among many existing contamination methods biological cleaning has become more popular lately. It took us some years to make investigations and to carry out a number of field tests in order to develop biological methods of cleaning soil and reservoirs from oil and gas condensate products. Our method is based on the use of special biological agents containing various active hydrocarbon oxidizing bacteria. It has been experimentally proved that biological agents of "Devouroil" possess the greatest oxidizing properties. "Devouroil" contains five kinds of hydrocarbon oxidizing bacteria of Pseudomonas, Rodococcus, Candida genera. These bacteria are extracted from natural ecosystems: underground waters, soils, reservoirs. As the agents are grown on oil distillate, they are very destructive to different oil products. We also proved the described microorganisms' ability to oxidize sulfate oil and hydrocarbon condensate, which are the most toxic components. For four years our colleagues have been cleaning soil and reservoirs contaminated with oil, black oil, gas condensate and other products of hydrocarbon origin. This method was used to treat different kinds of soil and ground (grass and arable land, swamp and forest) in actual hazardous situations involving oil and gas condensate spills. Besides it was successfully applied to clean sludge storage which had been filled with oil process sewage for several years. The efficiency of soil treatment depends on many factors: the age and degree of contamination, the depth and the type of polluted soil, climate. The cleaning effect of the proposed method proved 75–90% over the period of 2–3 months with initial pollution up to 150 g/kg, all the requires being fulfilled. The test results are represented in Table 1. Damp loose soils are cleaned more effectively. Already in the first months of the treatment process soils and biocenoses are reconstructed to a high degree. We used biological agent "Devouroil" in cleaning contaminated reservoirs (ponds, lakes, streams). If it was necessary oil products were collected mechanically first, then "Devouroil" and the immobilized hydrocarbon oxidizing bacteria on a special support material were placed into the polluted reservoir. The support material served as a mechanical barrier for oil products and microorganisms oxidized them. In running water any loss of immobilized microorganisms was prevented and the pollutants were localized thus increasing the efficiency of the method. The application of immobilized microorganisms on the support material in cleaning a stream from gas condensate provided the rise in the efficiency to 98% in two months and in the decontamination of the lake water loaded with black oil the effect reached 96% in three months of work. The method was more effective at hydrocarbon oxidizing bacteria concentration equal to 10-10 bacteria per one ml. First hydrocarbons C8 - C12 and C18-C21 then C12 -C17 were oxidized. Benzol and alcohol benzol resins were oxidized slowly but finally all fractions were treated. Thus the developed biotechnological treatment method is ecologically safe and economically effective. P. 759