REMEDIATION TRIALS FOR THE REUSE OF CONTAMINATED LAGOON SEDIMENTS BY LAN DFARMING (EX-SITU BIOREMEDIATION)

Sediments from a lagoon heavily contaminated with petroleum hydrocarbons, mainly diesel fuel, have undergone pilot-scale remediation trials using a landfarming methodology Additives, in the form of partially composted green waste, wheat straw and blended farm manure were added to the sediment to provide a population of micro organisms. The added material was essential for allowing aeration to occur, with very little aeration occurring in the sediment with no additives. The additives also improved the texture of the sediment in order to form a soil for reuse on another part of the site, to improve the environment in this area. Over the 53 weeks of the trials, a reduction in hydrocarbon concentration of up to 67% was observed. Due to the nature of the process, the breakdown of the hydrocarbon in the soil will continue to occur. A number of lines of evidence were used to assess the various ratios of additives that were used in the trials. These were the chemical analysis results from soil and leachate samples, seedling emergence and growth tests and earthworm toxicity tests. The earthworm toxicity tests proved to be particularly sensitive, which identified the most effective additive combination for generating a product suitable for use as topsoil.