Radioactivity in Oily Sludge and Produced Waste Water from Oil: Environmental Concerns and Potential Remedial Measures

Produced water separated from oil is usually returned to the environment and could permeate through the water table. If such water is contaminated with radioactive substances, it could create a definite threat to the water supply, especially in arid regions where ground water and overhead streams are sources of potable water. Low-level radioactive contamination of oily sludge is equally hazardous and also leads to detrimental pollution of water resources. We investigated the distribution of Ra, K and Ac in produced waste water and oily sludge and found abnormal levels of radioactivity. A total of 90 ground wastewater samples were collected from different sites for a period of one year. The presence of these radionuclides was identified by their characteristic gamma rays. The detection system consisted of a high-purity germanium detector. Our results show that about 20% of the samples exhibited 20–60 Bq/L radioactivity and ~6% of the samples exceeded 60 Bq/L. Roughly 70% of the experimental samples fell in the range of 2–20 Bq/L, which still exceeded the maximum admissible drinking-water limit 0.2 Bq/L.