Bioremediation of creosote-contaminated soil: a pilot-scale landfarming evaluation

A pilot-scale landfarming investigation of the effects of biostimulation and bioaugmentation on a creosote-contaminated (258.3 g kg^–1) mispah form (FAO: lithosol) soil, with a view to developing a cost-effective bioremediation methodology for creosote-contaminated soils was conducted in nine duplicate reactors, including two controls (Treatments 1 and 2). Treatments 3–9 were watered and aerated daily and Treatment 4–9 were monthly amended with mono-ammonium phosphate. Treatment 5–9 received further amendments as follows: Treatment 5, hydrogen peroxide; Treatment 6, indigenous microbial biosupplement; Treatment 7, sewage sludge; Treatment 8, cow manure; Treatment 9, poultry manure. Residual concentrations of creosote ranged between 29 and 215 g kg^–1 after sixteen weeks. The phenolics and the 2- and 3-ringed polyaromatic hydrocarbons (PAHs) were removed below detectable levels or to very low levels. The 4- and 5-ringed PAHs were removed by between 68 and 83%. Indigenous microbial biosupplement and sewage sludge were the most effective in creosote removal. Hydrogen peroxide did not significantly enhance microbial population and creosote removal. There was no significant difference between the results obtained from the treatments amended with organic manures. However, there was a significant difference between the effects of the organic manures and the indigenous microbial biosupplement. Results from this study suggests that a combination of the two treatment techniques (biostimulation and bioaugmentation) would be a better approach to treating soil contaminated with very high concentrations of creosote.