Bioremediation Of Polybrominated Diphenyl Ethers In Sediment

Decabromodiphenyl ether(BDE-209) is the main ingredient of bromine flame retardants. The environmental pollution caused by it draws more and more attention of people as time goes by. Thalia dealbata which is common in the river is used as the effective plant for phytoremediation. And Brevibacillus brevis and Enterococcus casselifavus were used to enhance the phytoremediation and meanwhile biostimulant was added to promote the growth of microorganism. The biostimulant and rhizosphere effects on physical and chemical properties of the sediment, and the impacts of rhizosphere effects on fluorescein diacetate(FDA) and removal rate were investgated through pot experiment. Mechanism about how the microorganisms enhanced the phytoremediation including concentration, species and distribution of polybrominated diphenyl ethers and changes of concentration organic acids and phospholipid fatty acid were analyzed. Phytoremediation pathway was also discussed.The addition of biostimulant which includes basic compounds increased the p H value of sediment and also had an effect on the growth of plant and oxidation reduction potential of sediment at the beginning of the experiment. The plant increased the removal rate of total nitrogen and total nitrogen in sediment. The planting of Thalia dealbata increased the removal rate of BDE-209 in sediment. Concentration of BDE-209 in the control samples reduced from 1.33 mg?kg-1 to 1.13 mg?kg-1, and concentration of that reduced to 0.97 mg?kg-1 in treatment group with plant. The removal rate of BDE-209 increased from 15% to 27%. GC-MS analysis suggested that BDE-209 existed in both ground and underground part of the plant, indicating the roots could uptake BDE-209 and transport it to the ground part of the plant.Brevibacillus brevis and Enterococcus casselifavus were chosed to enhance phytoremediation of Thalia dealbata. Addition of them to sediment increased concentration of phospholipid fatty acid(PLFA), suggesting the microorganisms were inoculated to the sediment successfully and they could grow and multiply normally. Concentration of PLFA Could be changed by the addition of pant and BDE-209. Rhizosphere effect and microorganisms may have an effect on the concentration of organic acids in sediment. BDE-209 might stimulate roots to secrete more organic small molecular substances which is beneficial to the removal of BDE-209. Results shows that Brevibacillus brevis coud enhance the effect of phytoremediation to the utmost extent. Addition of plant and microorganisms could promote metabolic capacity of carbon of microorganisms in sediment.The removal rate of BDE-209 wase raised to 66%, which is the highest compared with others.