Immobilized Microbes-plants Combined To Repair Fluoranthene Pollution In River Sediments

PAHs pollution in the river sediment becomes a increasingly serious problem.High molecular weight PAHs is difficult to be repaired because of its toxicity and poor degradation.In this paper,fluoranthene with high detection frequency and relatively high abundance was used as the representative material of high molecular weight PAHs.The degradation efficiency of fluoranthene by Penicillium purpurogenum strain DTQ-HK1 that was immobilized and added surfactant was studied under the rhizosphere of plants.The DTQ-HK1 was adsorbed and embedded by different carriers.Comparing the oxygen consumption rate of immobilized strain and short-term degradation of fluoranthene to optimize the immobilization methods,and then the long-term degradation rates of fluoranthene and resistance to environmental impact were researched.The results showed that adsorption immobilization was superior to embedment immobilization.Corncob with particle size of 10 mesh was the best carrier of adsorption immobilization.The degradation rate of fluoranthene by adsorption immobilized strain in liquid was 62.45%after 42 days,which was increased by 10.23%comparing with the free strain.The resistance ability to environmental impact(different temperature,pH and different concentration of heavy metal ions.)of strain immobilized by corncob was enhanced.In order to improve the fluoranthene degradation by adsorption immobilized bacteria,the glucose,maltose,HA,anthracene and phenanthrene mixture were chose as the external carbon source.The different carbon sources and dosage of carbon sources on the degradation efficiency of fluoranthene were investigated.The maltose was the most favorable for the degradation by immobilized bacteria,and the best dosage of maltose was Cfluoranthene:Cmaltose =5:3.The degradation rate of fluoranthene by immobilized bacteria with maltose was 100%,which was 13.86%higher than that without adding maltose.After the effect of immobilization technology on the degradation of fluoranthene was studied,the effect of surfactant addition on immobilized bacteria for fluoranthene degradation was further investigated.The effects of two kinds of surfactants(SDBS and Tween80)on the solubilization of fluoranthene,the activity of immobilized bacteria and solubilization effect of different condition(temperature,pH and ionic strength)were studied.The result showed that Tween80 had the better solubilization effect on fluoranthene and little effect on the activity of immobilized bacteria.On the basis of adding immobilized bacteria and maltose,the time that fluoranthenethe was degraded completely was reduced by 15 days,and the degradation rates was enhanced by 78%.Toxicity analysis of fluoranthene 42 days degradation products was evaluated by Pseudomonas aeruginosa.The results showed that the specific growth rate was 0.0117 h-1 after degradation by suspended bacteria,and was enhanced by 14.5%after degradation by immobilized bacteria.The specific growth rate were increased to 0.01876 h-1 after adding maltose and surfactant on the basis of degradation by immobilized bacteria.It showed that degradation ability of fluoranthenehe and metabolite by immobilized bacteria was enhanced obviously.Adding external carbon source and surfactant could further increase the degradation efficiency of fluoranthene and reduce the toxicity of fluoranthene degradation products.