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Improvements in Treatment of Waste from Petroleum Industry in Croatia

Wastes associated with exploration and production (E&P) activities in the petroleum industry have the potential to impact the environment. These wastes include hydrocarbons, solids contaminated with hydrocarbons, water contaminated with a variety of dissolved and suspended solids, and different types of chemicals. Common practice in Croatia includes disposal of solid E&P wastes into pits and underground injection of liquid E&P waste. The liquid phase is injected into dry exploration or depleted production wells, while the remaining solid phase is treated with lime for stabilization and solidification (S/S) and buried on site. This material is then covered with soil. Durn et al. (2004) showed that the release to the environment (especially to groundwater) of both inorganic and organic pollutants from lime-treated waste may be high for selected sites. E&P waste generated by the petroleum industry in Croatia from one central oilfield pit (COP) was investigated in order to find field-acceptable methods to reduce the amount of waste to be treated with S/S or some other method. A composite sample from COP was treated in the laboratory using a four-step procedure involving boiling water, condensate, and organophilic clay. Organophilic clay was used because of its ability to sorb hydrophobic pollutants. In the leachate of an E&P waste sample, the lowest values for the majority of inorganic and organic pollutants were observed following the fourth step (treatment with organophilic clay). This is also manifested in the lowest indicator of total discharge (ITD%) values for the fourth treatment step. Considering the concentrations of analyzed parameters in leachates and their ITD% values, the biggest effect for the majority of inorganic and organic pollutants was achieved between the first and the second treatment step. This suggests that treatment with boiling water is the most effective treatment for the majority of inorganic and organic pollutants. Concentrations of benzene, ethylbenzene, toluene, and xylene (BETX) in distilled water leachate are generally increasing after each succeeding treatment step. This shows that BETX is added to the E&P waste through condensate addition in the third treatment step. References: DURN, G., GAURINA-MEĐIMUREC, N., FRÖSCHL, H., MEANDŽIJA, I., VERONEK, B. & MESIĆ, S. (2004):The Geochemical and Mineralogical Assessment of Lime Stabilized Waste from the Petroleum Industry in Croatia.- Journal of Energy Resources Technology, 126, 112-118.

waste treatment; petroleum industry; Croatia

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