Geochemical and Mineralogical Assessment of Lime Stabilized Waste From Petroleum Industry in Croatia

The aim of this study was geochemical and mineralogical assessment of materials from two already closed pits. Total testing and leachate testing (Equilibrium Leach Test and Sequential Leach Test) of topsoil, waste stabilized with lime and underlying rock was performed on composite samples. Analysis of underground water from underlying rock was also accomplished. Major pollutants in stabilized waste from investigated locations differ. High total values of some heavy metals in stabilized waste from one of the investigated locations can probably be attributed to high barite content (mercury, zinc and cadmium) and pipe dope (lead). Mercury, zinc and cadmium are enriched in the organic-sulfide fraction that might indicate they are tied up as sulfide impurities in barite. In distilled water lecheate of stabilized waste from this location higher concentrations of Pb, Hg and TOC were observed. In the stabilized waste from the second location high total values of TPH, PAH and BTEX were detected, while distilled water lecheate is enriched in Hg, AOX, TOC and TPH. This investigation shows that stabilization with lime is not always suitable method for treatment of wastes from petroleum industry, particularly those that are contaminated with both organic and inorganic contaminants. Proper characterization of the waste material to be processed is needed in order to select the most appropriate method of treatment. Our ongoing research study uses different pretreatment techniques and different absorbents (organophilic clay, zeolite, calcined siliceous earth, etc.) to preferentially absorb organic contaminants that can be used before stabilization/solidification.