Potential Use of Polyacrylamide Encapsulation for Treatment of Petroleum Drilling Cuttings and Hydrocarbon Contaminated Soil

Mineral soil of alluvial origin, contaminated with diesel+lubricating oil (1:2), was treated with a commercial polyacrylamide product at 100 % of the distributer recommended dosage, producing a reduction in hydrocarbon concentration (EPA 9074) of 76 % that remained stable during the study period (38 days) and even after thermal treatment (60 oC, 18 hrs.). Increasing the dosage to 150 % did not improve the treatment results, but repeating the treatment (at 100 %) resulted in a slight additional reduction (4 %). Similar results were obtained with oil-based drilling cuttings (~60 % reduction at both 100 % and 150 %). Pre-drying of the drilling cuttings prior to treatment did not improve the hydrocarbon reduction, but it did produce smaller, potentially more stable aggregates (0.5 – 1-0 mm in diameter). The treatment of organic soil resulted in a similar reduction in hydrocarbon concentration (65 %) and a reduction of acute toxicity (Microtox) to below background levels, however this effect was not stable. An additional application (including mixing) of the polyacrylamide product resulted in partial disintegration of the organic fibres and release of the stabilized hydrocarbons, measuring an overall increase in hydrocarbon concentration of 19 %.