Evaluation of treatment efficiency of drilling waste with thermal desorption technique

This study investigated the treatment efficiency of oil-based mud contaminated drilling waste using the Thermal Desorption Unit (TDU) technique, and also monitored pollutant gas emissions associated with the process. Composite drilling waste feedstock samples were characterized. Heavy metals were determined spectrophotometrically while total petroleum hydrocarbons (TPHs) (benzene, ethyl benzene, toluene, naphthalene and xylene) were determined chromatographically. Digital air monitors and a high volume gravimetric air filter sampler were used to monitor gaseous emissions. Variation plots and Sudent's t-test were used to analyze data. The concentrations of the contaminants decreased significantly after treatment (t=0.032) at P<0.05 from 21520.00 to 71.61 mg/kg (TPHs), 0.001 to 0.0005 mg/kg (benzene), 7.55 to 0.001 mg/kg (toluene), 3.64 to 0.001 mg/kg (xylene) and 5.80 to 0.001 mg/kg (naphthalene). Very high treatment efficiencies of 99.67, 99.99, 99.97, 99.98, 99.47, 97.48 and 87.13% were recorded for TPHs, toluene, xylene, naphthalene, V, moisture contents and electrical conductivity. Gaseous emission levels were below regulatory limits, even as relatively highest emissions were recorded for suspended particulate matter (15.0 ± 0.2 mg/m³), and least emissions for CH4 (0.39 ± 0.1 mg/m³).