BDE209 Aerobic Degradation And The Influential Factors By Bacillus Thuringiensis

People have been great concerning on PBDEs pollution and its correspondingly ecological risks existed in E-waste recycling area. The research performed on the characteristic and impact factors of BDE209 degradation by Bacillus thuringiensis. In the work, a strain being able to degrade BDE209 in aerobic condition was screened, identified and its characteristic degrading BDE209 was investigated. The effect of bio-surfactant, Cd on BDE209 degradation by the strain was also observed. Furthermore, the mechanism of BDE209 degradation by the strain was explored in the aerobic condition.The strain, isolated from the contaminated soil, strongly tolerable of Cd and effective in degrading BDE209 was identified as Bacillus thuringiensis and named as Bacillus thuringiensis J-1. The factors such as inoculation amount, cell age, pH, temperature, pollutant concentration, dissolved oxygen, substrate concentration and salinity significantly affect the efficiency of BDE209 degradation by J-1. Sucrose as the additional carbon source could mostly promote J-1 degrading BDE209.Biosurfactant could enhance the efficiency of BDE209 degradation by J-1. The factors, for example initial concentration, surfactant concentration, temperature, pH, dissolved oxygen etc., could greatly impact on BDE209 degradation by J-1 in the presence of bio-surfactant. Treating the BDE209 solution forl day with the bio-surfactant could effectively increased the efficiency of BDE209 degradation by J-1.In BDE209-Cd combined pollution system, the J-1 whose age was 12-24h degraded BDE209 and absorbed Cd effectively. The dynamic equation of BDE209 degradation by J-1 met the first order kinetics. The way of bacteria inoculation had significant influence on the remediation of BDE209-Cd combined pollution. Addition of 10-20mg/l of bio-surfactants could improve the removal efficiencies of BDE209 and Cd in combined pollution. The result of electron microscope scans showed that the cell of J-1 maintained integrity in BDE209-Cd combined pollution system, which indicated the J-1 was strong tolerance to the kind of combined pollution.The result of enzymatic degradation showed that the internal and external enzyme both could degrade BDE209, but the intracellular enzyme was more effective. The environmental factors such as pH, temperature, and dissolved oxygen could affect the activity of extra-cellular enzyme. A certain concentration of Cd could improve the enzymatic degradation. The analysis degrading of products by FT-IR and GC-MS showed that BDE209 was transformed into octa-BDEs by broking off the Br on the benzene ring with the action of microorganisms. At the same time, some oxygen groups such as hydroxyl, carboxyl also produced.