Bioremediation of PAH-Contaminated Soil

Biodegradation of PAH-contaminated soil was studied by a slurry reactor test and a soil column test. The initial total concentration 1000 ppm PAH soil was decreased to 50…100 ppm in the slurry reactor in 6 weeks. In the soil columns the concentration was decreased to 120…770 ppm in 4 weeks. Addition of coniferous tree bark enhanced degradation significantly in the soil column tests, but not in slurry reactor tests. Use of inoculants had only a slight positive effect in slurry tests; the effect was even negative in the degradation of 5–6 ring compounds in some soil column tests.The experiences were applied to practical scale by using a composting method where bark is used as a bulking agent. High moisture content is maintained in the heap and the leaching water is circulated until the target concentration is reached. The different functions of the bark addition is discussed.