The Study Of BDE-209Adsorption On Sediment And Biodegradation

BDE-209degradation by microbial and adsorption on sediment were studied.The main works included the effects of BDE-209adsorption on sediment by changingenvironmental factors and adding heavy metals Cd, Pb; degradation of BDE-209byBrevibacillus brevis in water system; researching the effects and the mechanisms ofBDE-209degradation by microbial and adsorption by sediment in sediment-watersystem through addition of heavy metals cadmium, lead. The results were as follows.The adsorption kinetic and isotherm of BDE-209on sediment indicated thatthere were two relatively fast stages of BDE-209adsorption on sediments, and theadsorption equilibrium time was about24h. When BDE-209concentration rangedfrom2to10mg L^-1, its adsorption on the sediment fit well with the Langmuir model.In addition, changing pH in water exhibited little effect on adsorption of BDE-209onsediment. With the increase of sediment concentration, sediment adsorption amount ofBDE-209also increased, but not simple geometric increase.Addition of surfactants had significant influence on the saturated adsorptionamount of BDE-209on sediments. At the concentration of20mg L^-1, ionicsurfactants SDBS, CTAB promoted BDE-209adsorption on sediment, whilenon-ionic surfactants Tween80, TX^-100restrained it. The equilibrium adsorptionamount （Q_e） of BDE-209exhibited the following sequence: Q_e(TX^-100)＜Q_e（Tween80）＜Q_e（No）＜Q_e（CTAB）＜Q_e（SDBS）. When heavy metals concentrationranged from1to6mg L^-1, the mount of BDE-209on sediment would be inhibited.When the concentration of BDE-209was2mg L^-1, the inhibition was unconspicuous;while it became significant when the concentration of BDE-209was equal or greaterthan4mg L^-1.Degradation of BDE-209by B. brevis in water system fit well with the first orderkinetics reaction equation. When the BDE-209concentration was2mg L^-1, B. brevisdegradation efficiency of BDE-209in water system reached21.4%within24h,7days of the degradation rate was44.8%. When the concentration of BDE-209was2,4, 6mg L^-1, degradation rate of BDE-209in sediment-water system reached30.5%,38.4%,25.7%respectively. When the BDE-209concentration was2mg L^-1,degradation rate of BDE-209in sediment-water system reached45.7%afterremoving of iron and manganese oxides and organic matter from sediment.Heavy metals Cd and Pb showed inhibitory effect in B. brevis degradation ofBDE-209in water system, and with the heavy metal concentration increases, theinhibition enhanced. When the concentration of heavy metal Cd, Pb was1mg L^-1, thedegradation rate of BDE-209were higher than without heavy metal in sediment-water system. While the degradation rate will fall obviously if the concentration ofheavy metal Cd, Pb greater than2mg L^-1. When the concentration of heavy metal Cd,Pb was1mg L^-1, B. brevis degradation rate of BDE-209close to zero after4days.