| More and more rubbish is released into the environment along with the development of industry, heavy metals are included. Heavy metals could enter into the environment through many ways, as a result, it brings great loss and damage to the ecology environment. Sediment is the place that the large deal of halobios and marinebenthos live in, and heavy metal contamination of sediment is harmful to the halobios and marinebenthos, and may destroy the health of human being by the food chain. There are three main methods to remediate heavy metal pollution, including physical method, chemical method and phytoremediation and bioremediation method. The disadvantages of physical and chemical method are the high cost and second pollution, respectively, phytoremediation method has long period, so it's unfit for cosmical application, bioremediation is not suitable for soil and sediment.The content of this dissertation was divided into five parts, the first part is summarization of literature; the second part is isolation and identification and fermentation of bacteria which produce biosurfactant; the third part is the extraction and evaluation of biosurfactant; the fourth part is the study of heavy metal removal by biosurfactant; the last part is the conclusion and expectation.In this study, 14 strains were isolated from oilfield wastewater and mixed bacteria in the Lab, and fermentation conditions were studied, one strain that produces biosurfactant was selected, the best fermentation condition was determined, and the structure of the biosurfactant was analysed, the results suggested that it was identified as lipopeptide biosurfactant. In addition, remediation of heavy metal pollution by biosurfactant was seriously studied , the conclusions were as follows:(1) 14 strains were isolated from Shengli oilfield wastewater and mixed bacteria in the Lab after 3 times enrichment; one of them could reduce the surface tension of fermentation liquor dramatically after fermentation, which was named L-Z-1. It was identified as bacillus subtilis through Biolog and physiological biochemical testing. (2) The best carbon and nitrogen source for fermentation were determined as olive oil and NaNO3, respectively, and the best fermentation conditions were (in grams per liter of water): olive oil, 20; NaNO3, 8; NaCl, 5; K2HPO4, 3; KH2PO4, 3; beef extract, 1; microelement solution, 4 mL; pH 7.0, and incubated in a gyratory shaker at 160 rpm for 72 h at 37 oC. The fermentation production was extracted, it was lipopeptide. The property research indicated that the cmc is 150 mg/L.(3) In the artificially contaminated sediment experiment, copper removal efficiency increased as the increasing of biosurfactant concentration; in natural pH, 66.02 % copper could be removal by 150 mg/L biosurfactant solution, when biosurfactant concentration adding to 300 mg/L, copper removal efficiency got to 66.67 %. Removal efficiency was also affected by pH, and got to 77.88 % when pH was 10.(4) The removal efficiency for natural sediment was worse than artificially contaminated sediment, the control water could remove only a small amount of copper, lipopeptide solution can remove 35.57 % copper when pH was 11; washing effect of various species of copper had an evidence difference at different pH conditions; Washing times can affect copper removal, 63.98 % copper was removed after 5 times washing by biosurfactant solution; In addition, the filtrated and centrifugal fermentation liquor was able to remove copper from artificial contaminated sediment. A compare between lipopeptide and SDS solution (163.6 mg/L, the same as lipopeptide solution) was made to remove copper from sediment, and it suggested that SDS could hardly remove copper.(5) The lipopeptide biosurfactant can also remove lead from artificially contaminated sediment, 150mg/L biosurfactant solution can remove 51.43 % lead, at pH 10, 88.56 % lead was removed.(6) SEM and ultrafiltration experiments indicated that copper was removed by the complexation with biosurfactant micelle.
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