Pollution potential of the wastes of used oil treatment plants and their possible remediation techniques

Abstract

In this research, wastes of used oil treatment plants have been studied for their pollution potential and geotechnical characteristics. A random sampling plan was used to collect 11 samples from the dump site. Moreover, statistical analysis indicated that six samples were required to prepare a representative sample for the wastes. Thus, a mixed sample was prepared to determine moisture content, pH, Atterberg limits and density of the waste. The analysis of organic compounds and heavy metals showed the presence of total petroleum hydrocarbons (TPH) and Barium as the main pollutants. The results also showed waste as a fine-grained soil heavily contaminated by petroleum hydrocarbons. The mean concentration of TPH was more than 216 g/kg, which is 832, 108 and 433 times greater than the acceptable cleanup levels for diesel range organics, oil range organics and TPH, respectively. Nevertheless, heavy metals concentrations are lower than proposed cleanup levels for industrial area. The moisture content, pH, liquid limit, plastic limit, plastic index and density of the mixed sample were 12.26%, 9.6, 25.91, 15.83, 10.08 and 1.22 g/cm3, respectively. After that, several remediation techniques were evaluated to propose the best one based on the physical and chemical properties of the waste, the applicability of the method and implementation costs. Finally, solidification/stabilization technique using organophilic clay as the stabilizer, incineration and bioremediation techniques was recommended for cleanup of the site.