Improving oil contaminated soil characteristics through the use of combined treatments necessary for phytoremediation technologies

The objective of this study was to determine the possibility of using fly ash amendment optimal doses from a thermal plant, mixed with a fertilizer agent, anaerobically stabilized sewage sludge to reduce stress caused by the presence of large amounts of 113.5 g·kg-1 D.M. of oil product, TPH, (Total Petroleum Hydrocarbons) in polluted soils. The study was conducted in vegetation pots to determine the emergence degree and development of a culture of forage leguminous plants of Lotus corniculatus species, bird’s foot trefoil. The experimental variants were treated with fly ash and fertilized with 500g per vegetation pot of anaerobically stabilized sewage sludge. Studies were done in comparison with experimental versions cultivated with bird’s foot trefoil of polluted soil treated with fly ash, polluted soil fertilized untreated with ash. The addition of fertilizing agent mixed with small amount of fly ash caused a emergence degree of 50-60%, and the reduction of the content of oil product, after 4 months of vegetation, by 29.9%. The maintaining of vegetation in perennial regime specific to this plant species demonstrates the plant tolerance to conditions created by the treatment of polluted soil with adequate amounts of fertilizer and fly ash amendment.