Study Of Combined Remediation Effects Of Ryegrass-Staphylococcus Auricularis On Cu And Pyrene Containmnated Water

The effects of ryegrass (Lolium perenne L.) and Staphylococcus auricularis on the remediation of Cu and pyrene contaminated water were studied using hydroponic culture experiments. This study has focused on the remediation efficiency of Cu and pyrene. Experiments were also carried out to study the interaction mechanism between ryegrass and S.-auricularis on combined remediation.The results indicated that treatment conditions such as pH, treatment time, the dosage of S.-auricularis and the fresh weight of ryegrass influenced pyrene removal efficiencies.S. auricularis played an important role in plant-microorganism combined bioremediation. The removal rations of Cu by ryegrass and S. auricularis were over 85% when the initial Cu concentrations in the water body were between 5～30 mg·L-1, which was more efficient than the single remediation by ryegrass. S. auricularis's better resistence and adsorption towards Cu were revealed, and up to 40.6 mg·g-1of Cu (dry weight) was observed in the shoots of ryegrass when treated with 100 mg·L-1 Cu. The Cu-biosorption capacity of S. auricularis consequently resulted not only in the increase of chlorophyll content in the leaves and plant biomass but also in the decreases of Cu concentrations both in the roots and shoots of ryegrass.The shoot and root biomass of ryegrass significantly increased by 5%～8% and 9%～42%, respectively, when inoculated with S. auricularis. Both ryegrass and S. auricularis accumulated a certain amount of Cu and pyrene. And up to 1.08 mg-kg-1 of pyrene (freash weight) was observed in S. auricularis. The removal efficiencies of Cu and pyrene by jointed ryegrass and S.-auricularis were 90% and 77%, respectively.The ryegrass exudates included about 2g-L-1 oxalic acid and the amount of carbohydrate remained at 0.05～0.14 g·L-1. S. auricularis enhanced the pH of nutrient solution, but reduced the amount of oxalic acid and carbohydrate. Pyrene reduced the amount of carbohydrate, and Cu caused the oxidative damageof ryegrass leaf. S. auricularis strengthened the resistance ability of ryegrass to Cu and pyrene contamination. Observation by scanning electron microscope indicated that a larger number of hair roots were grown on the fibrous root under the stimulation of pyrene, S. auricularis not only increased hair roots, but also relieved the toxic risk to the fibrous and hair root. It also proved the cell of S. auricularis adhere to the root of ryegrass.