Effects of Two Kinds of Herbage Crops on the Removal of High Molecular Weight PolycyclicAromatic Hydrocarbons in Sludge

The purpose of this study was to compare the effects of two herbage crops (awnless brome and alfalfa) on the removal of high molecular weight polycyclic aromatic hydrocarbons (HMW-PAHs) in sludge, including 9 PAHs. The results showed that Awnless brome and alfalfa had similar removal percentages for the total Σ9 HMWPAHs in the sludge, which were 85.75% and 85.08%, respectively. However, these two plants were different in the removal percentages of individual PAHs, for example, awnless brome had higher removal percentages for the 4-ring compounds (Pyr, BaA, Chry, BbF and BKF), while alfalfa showed higher removal percentages for the 5-ring and 6-ring compounds (BaP, DbA, Bghip and InP). The activities of catalase and polyphenol oxidase in the sludge planted with alfalfa were significantly higher than those in the sludge with awnless brome, while the activities of dehydrogenase in these two kinds of sludge were opposite. In conclusion, awnless brome and alfalfa could be directly used for the remediation of HMW-PAHs-polluted sludge, and awnless brome inclined to degrade the HMW-PAHs with 4 rings, while alfalfa tended to degrade the HMW-PAHs with 5 and 6 rings.