Presence of Eisenia fetida Enhanced Phytoremediation of Anthracene by Ryegrass

The efficiency of co-application of Eisenia fetida and Ryegrass (Lolium perenne) was evaluated in a process so called as earthworm-assisted phytoremediation. Anthracene was used as a model compound for PAHs. The experiments were carried out on a loamy soil in the greenhouse conditions with anthracene concentration of 500 ppm. There were four different treatments which were applied in four replications. The treatments were plant without earthworm, plant with earthworm, earthworm without plant and a control. At the end of experiment, the soil samples analyzed for residual anthracene by HPLC. Results showed that, phytoremediation using ryegrass could remove 81% of anthracene; however, the rate of removal was 92% when Eisenia fetida was applied simultaneously. Eisenia fetida alone could also remove the initial concentration of anthracene by 40%. Although, ryegrass itself could remove anthracene significantly, the employment of earthworm, together with plant was more efficient than each of them individually. The application of Eisenia fetida could also enhance the growth parameters of ryegrass significantly. The plant dry weight, root length, shoots length, and root volume, has been increased in the presence of Eisenia fetida. The number of live earthworms was also increased in the planted pots, indicating the helpfulness of the plant for survival of the earthworm in the PAH-contaminated soil. Although, plant and earthworm use completely different mechanisms for anthracene degradation, they improve efficiency and survival of the three-component-system.

Keywords:

Bioremediation , Earthworm , Lolium perenne , PAHs , Plant-assisted Phytoremediation