Evaluation of drum bioreactor performance used for decontamination of soilpolluted with polycyclic aromatic hydrocarbons

A laboratory-scale drum bioreactor system was used to study engineering asp ects of soil bioremediation. Polycyclic aromatic hydrocarbons (PAHs) were c hosen as contaminants in soil. In the operation of the reactor, different m ixing strategies were applied according to the size of soil without separat e washing of sand. The effect of the water content of the soil mixture on s olid mixing time and phenanthrene degradation rate was of particular intere st. At 20% water content, which was below the saturation level, the mixing effficiency of soil and the degradation rate of phenanthrene was lower than those at 30% or 40% water content. Optimal water content was variable acco rding to the soil texture. The drum bioreactor was operated under optimal w ater content and PAH concentration (fluorene, phenanthrene, anthracene, pyr ene) and microbial numbers were measured in each soil phase (sediment and s uspension). Over 95% of PAHs with three or four rings (fluorene, phenanthre ne, anthracene, pyrene) were degraded at 270 mgkg(-1) soil within 20 days. The degradation rate of PAHs in the suspension phase was higher than that i n sediment phase. (C) 1999 Society of Chemical Industry.