Study On Insolation And Identification Of Bacterial FDBS₁,the UV Mutagenesis And Immobilized Cells In Degration Of Formaldehyde

As an important chemical reagent and chemical raw material,formaldehyde has been widely used in many fields,such as resin production,medicine,decoration materials and so on.However,formaldehyde wastewater could cause environmental pollution.Currently,some measures may be used to treat formaldehyde wastewater such as physical method,chemical method and biological method,which have their own advantages and limitations.Biological method is relatively convenient and environmentally friendly for removing formaldehyde.As a native toxin,formaldehyde has strong toxic effect on the organism and high concentration of formaldehyde even.Therefore,it is very important to select the microorganisms that can tolerate high concentration formaldehyde wastewater.The aim of the research was to isolate a highly tolerant and highly active strain which can metabolize formaldehyde,then investigate the culture conditions and ultraviolet mutagenesis in degradation of formaldehyde and the characteristics of immobilized cells by gel beads.The research provided a basic study for constructing a high tolerance and efficient bacteria for formaldehyde degradation and the application for biological treatment technology about formaldehyde industrial wastewater.The main contents are as follows:Two strains of formaldehyde degrading bacteria were isolated from the wastewater of a printing and dyeing factory in Hohhot.The number 1 was used as the experimental strain,and the strain was identified as Bacillus tequilensis and named FDBS₁ by morphological observation,physiological and biochemical characteristics and homology analysis of 16 S rDNA.The culture conditions of FDBS₁ were optimized by single factor experiment and orthogonal experiment.The optimized medium was NaCl 5 g/L,peptone 10 g/L,and the trace elements were 0.7 m L/L.The optimum culture conditions were as follows: pH=8,160 rpm,37 ? for 16 h.Under optimum conditions the formaldehyde of 2000 mg/L could degrade 985.34 mg.Formaldehyde concentration has an effect on the degradation rate of FDBS₁.When the concentration of formaldehyde was 1000 mg/L,2 h could be degraded completely.When the concentration of formaldehyde was mg/L,the degradation rate of h was more than 7,which was more than 90%.For the low concentration of formaldehyde wastewater,the bacteria have good reuse and genetic stability.The degradation process is a process of entropy increasing,and the degradation process of low concentration accords with the two order kinetic model.The degradation efficiency of FDBS₁ was improved obviously through ultraviolet mutagenesis.For the 2000 mg/L formaldehyde,the degradation rate increased by14.11%¹5.72%,and FDBS₁ had good genetic stability,the degradation rate remained at about 80%.The embedding method was used to fix the FDBS₁.For the 1000 mg/L Formaldehyde solution,the removal rate could reach more than 80%.