Biodegradation of phenanthrene in soil.

We investigated the potential of an aerobic polycyclic aromatic hydrocarbon (PAH)-adapted consortium to degrade phenanthrene in soil. Optimal degradation conditions were determined as pH7.0 and 30 degrees C with a water content of 100% wt soil/wt water (w/w). At a concentration of 5 microg/g, phenanthrene degradation (k1) was measured at 0.0269 l/hr with a half-life (t(1/2)) of 25.8 hrs. Our results show that the higher the phenanthrene concentration, the slower the degradation rates. Phenanthrene degradation was enhanced by treatment with yeast extract, glucose, or pyruvate, but was not significantly improved by the addition of acetate. Degradation was delayed by the addition of either compost or potassium nitrate and enhanced by the addition of nonionic surfactants (Brij30, Brij35, Triton X100 or Triton N101) at critical micelle concentration (CMC). Phenanthrene degradation was delayed at levels above CMC.