| The biodegradation of pyrene and biosorption of cadmium by a bacterial strain (Stenotrophomonas maltophilia) were studied in this research, including the characteristics of S.maltophilia growth, biodegradation and biosorption capability, the treatment of pyrene-Cd combined pollution in water-sediment systems with strain, and the interaction mechanism between strain and pyrene-Cd.S.maltophilia could utilize pyrene as the sole carbon source optimally at 25℃and pH 8.0. The strain grew well when pyrene concentration was 0.5 to 2mg/L. However, excess pyrene would inhibit the cultivation. The growth of bacteria was significantly affected in combined pollution system when pyrene concentration was 2mg/L and Cd concentration was 0.1 to 10mg/L, cell growth decreased with increasing cadmium concentration.The highest degradation efficiency was 65.74% when initial pyrene concentration, temperature and pH value were 2mg/L,25℃and 8.0, respectively. The degradation of pyrene was promoted in complex pollution system with cadmium concentration 0.1 to 0.5mg/L. Nevertheless, higher concentration cadmium would depress the degradation.The biosorption equilibrium conformed to the Langmuir equations. Infrared spectroscopy analysis indicated that the main functional groups participated in Cd adsorption were C-H, N-H, O-H.S.maltophilia treated pyrene-Cd combined pollution in water-sediment systems effectively. The degradation efficiency of pyrene was 75.06% and the concentration of cadmium in water was decreased to 0.175mg/L from initial lmg/L after nine days.Scanning electronic microscope (SEM) observation exhibited that S.maltophilia could maintain normal growth condition in pollution system, thus ensuring their basic capability of degradation and biosorption. The strain would release Na+, NH4+, K+, Mg2+ and Ca2+ during the process of degradation and biosorption. FTIR analysis showed that the remediation process mainly related with hydroxyl, amide groups, C-H. |
