The Isolation Of Lambda-cyhalothrin Degrading Bacteria And The Research Of Its Degradation Characteristics

In this dissertation, taking Lambda-cyhalothrin as a model pollutant, its analytical method, degrading bacteria enrichment and isolation, characterization of its biodegradation were studied systematically. The main items as following:The extaction and analysis method of Lambda-cyhalothrin in liquid media were set up, including UV-Spectrophotometric method and Gas Chromatography method. The residual Lambda-cyhalothrin was extracted with CH₂Cl₂ and C₆H₁₄ in UV Spectrophotometric method and Gas Chromatography method, respectively. The R² of standard curve was 0.9943 and 0.998 in UV-Spectrophotometric method and Gas Chromatography method, respectively. The two methods could meet the requirement for analysis of Lambda-cyhalothrin residue.The Lambda-cyhalothrin degrading bacteria were isolated by direct way and selective enrichment from wastewater of pesticides production. 32 bacteria strains were isolated in all, 12 strains of which could degrade Lambda-cyhalothrin in evidence. 3 strains were proved to have highly degradation rates to Lambda-cyhalothrin by further screenings. Strains BD-e, BE-land BE-6 has 40.1%,57.3% and 36.8% degradation rates respectively.The degration characteristics of BE-1 strain was studied. BE-1 degrading capacity was influent by pH and Temperature, and the optimal pH and Temperature was 7.0 and 30℃. The effects of initial Lambda-cyhalothrin concentration on the strain BE-1 could not be ingored. Lambda-cyhalothrin was accelerate and restrain the growth of BE-1 strain at low concentration and high concentration, repectively. The effects of inoculum and volume of ventilation on the degrading could be ingored. Strain BE-1 could degrade Lambda-cyhalothrin in its 50mg/L liquor medium,with 55% degrading rate in 48h, and with 60.2% degrading rate in 120h.Effects of temperature, pH and initial concentration of Lambda-cyhalothrin on the BE-6 degrading characteristic were studied by orthogonal experiment. The results indicated that the optimal level was temperature 25℃, pH 7.0 and the initial concentration of 100mg/L.