[Process fundamentals and field demonstration of wheat straw enhanced biodegradation of petroleum]

A new bioaugmentation method utilizing wheat straw to enhance salt leaching and the subsequent petroleum biodegradation by consortia of bacteria and fungi was proposed. The present study aimed at the effects of wheat straw on the growth and the degradation behavior of E. cloacae and Cun. echinulata, the two species of the consortia. In the laboratory experiments, it was shown that the addition of 5% (mass fraction) straw led to an increase of biomass by 25- and 3-fold to the bacteria and fungi, respectively. The biodegradation ratio of total petroleum hydrocarbon (TPH) was elevated from 29.2% to 48.0% after 468 h treatment. The biodegradation ratio of alkane and aromatic hydrocarbons in petroleum were increased from 31.5% and 39.1%, to 55.7% and 55.9%, respectively. The field demonstration was carried in an area of 6400 m2, in which the bacteria and fungi were inoculated after salt leaching in the presence of wheat straw. The addition of wheat straw in the contaminated soil led to an increase by 158- and 9-fold to the bacteria and fungi, as compared to their counterpart in the controlland without wheat straw, at 25 days after the inoculation. The content of TPH was down to below 0.3% while the maximum biodegradation ratio of TPH reached 75% after 45 days treatment. These results demonstrated the effectiveness and high potential of the wheat straw enhanced bioaugmentation of petroleum-salt contaminated soil.