ИСТИНА

The approach to mitigate the drill cuttings impact on the environment Kovaleva E.I.1,2, Guchok M.V.1,2, Ledovskikh S.S.2, Terekhova V.A.1 1Lomosonov Moscow State University, Soil Science Faculty, Moscow, Russia, 2Ecoterra Autonomous Non-Commercial Organization (ANO "Ecoterra"), Moscow, Russia katekov@mail.ru, ekaterina.kovaleva@soil.msu.ru Oil extraction impacts the environment by the landfill of drill cuttings (DC). The DC composition is determined by chemical composition of drilling fluids, oil, and produced water. The main contaminants, entering to the environment from DC landfills, are petroleum hydrocarbons (PHC), chlorides and metals. Finding approaches to changes the DC characteristics and produce the mixture like safe ground is a crucial problem. We sought the best additives to DC, modeling physico-chemical properties and evaluating DC mixture toxicity. DC was sampled in Yamalo-Nenets Autonomous Okrug, West Siberia. We mixed DC with sand to improve physical characteristics, shungite or kieselguhr to increase the sorption capacity, phosphogypsum (PG) to regulate acid medium of mixtures. The additives were tested independently and in a mixture with DC in different ratio and with different PHC doses (30 - 70 g kg-1). We tracked contaminant transition from mixtures into water, flowing one-year precipitation amount through samples. PHC were detected by gas chromatography, chlorides - ion liquid chromatography, metals - inductively coupled plasma mass-spectrometry. Bioassay (crustaceans, infusorians, algae, terrestrial plant test) was used to evaluate the mixture toxicity. Shungite adding as 5% from DC amount reduced the chloride content from 14.4 to 7.2 g L-1 and didn’t decrease PHC penetration into filtrate. 10% shungite additive decreased PHC content in filtrate from 1.7 to 0.5 mg L-1 and chloride content from 15.7 up to 6.1 g L-1. Kieselguhr adding as 5% from DC amount adsorbed up to 98% of PHC and only 10% of chlorides; while 12-15% didn’t change chloride content in filtrate significantly. 2-3% of PG additive shifted the pH values of mixture water extracts to 7.0-8.5 range and transformed metal-ions in non-exchangeable forms. Kieselguhr in amount of 5% from pure DC is the best to adsorb PHC (up to 50 g kg-1) in mixtures. 10% shungite adding allows decreasing of chloride content up to 40% in DC mixtures. We approved the non-toxic characteristics of mixtures using bioassay. The major advantage of the proposed approach is in selection ratio and additives to produce the safe ground as an effective recultivant to restore degraded lands. Acknowledgments .This study is carried out in the framework of research directions of Moscow State University: “Development of soil technology for food and environmental safety, their theoretical and methodological bases” and “Scientific and theoretical foundations of environmental regulation, environmental components quality assessment and ecological management”