ABSTRACT
The present study focuses on the development of a new chemical treatment method for naturally occurring radioactive materials (NORM) scale wastes from the oil industry. The method consists of three-stages, including the separation of oil using the Fenton oxidation process at room temperature, the complete dissolution of soluble and slightly soluble salts and separation of Ra and Pb isotopes. The proposed method can be considered as an innovative procedure for NORM scales treatment and radionuclides separation, which in turn support the radioactive waste management with economic benefits.
ABSTRACT
Contamination of soil with 226Ra is a common problem in the oilfields, leading to costly remediation and disposal programmes. The present study focuses on the chemical fractionation and mobility of 226Ra in contaminated soils collected from an oilfield using a three-step sequential extraction procedure (BCR). The total activity concentrations of 226Ra in contaminated soils were measured and found to be in the range from 1030 ± 90 to 7780 ± 530 Bq kg-1, with a mean activity concentration of 2840 ± 1840 Bq kg-1. The correlation between the total concentration of 226Ra and soil properties, mainly pH, LOI, Corg, clay and Ca, was investigated using the principal component analysis method (PCA). The chemical fractionation of 226Ra was studied using the sequential extraction method (BCR). The highest fraction of 226Ra (27-65%) was found to be in the acid-reducible fraction, which suggests that 226Ra is mainly bound to FeMn oxides. The BCR method showed that high percentages of 226Ra were found to be in mobile soil phases (between 45 and 99%). Consequently, groundwater contamination could occur due to the remobilization of 226Ra from soils under normal environmental conditions. However, the obtained results could be useful to reduce the volume of NORM wastes generated from the oilfields and decision-making process for final treatment and disposal of NORM-contaminated soil.
