Study Mechanism And Kinetic Of Cl O4-bio-degradation With Redox Mediators

With the widely use of perchlorate in industry and its tremendous environmental damages, how to properly deal with the perchlorate pollution becomes a hot spot. Various technologies exist to remove perchlorate from water, But it is importantto develop an economic, applicable and effective method. For the slow biological reaction rate, redox mediator can enhance it by accelerating electron transport rate, but the acceleration mechanism is not clear. Thus, this research isolated a high-efficiency perchlorate reduction strain firstly, and then the characteristics and mechanism of perchlorate bio-degradation with redox mediators were carried out in detail.A perchlorate reduction Acinetobacter bereziniae strain GWF, which was a Gram-negative, non-fermentative, facultative anaerobe character, was isolated from domestication sludge of maturity. The growth and denitrification property were investigated in this paper. Results of the experiment showed that the optimized growth conditions were the temperature of 30℃, the pH range of 7.5 to 8.5 and the carbon(CH3COONa) concentration of 1.2g/L and the C/ClO4- ratio of 10:1. NO3- was beneficial to Cl O4-degradation process in its concentration range of 0 to 30mg/L. The influence of SO42- was connected with its concentration on ClO4- degradation. ClO3- inhibited inhibited perchlorate degradation with its concentration of 0.2 to 1.0m M. And there maybe have ClO3-during the process of ClO4-degradating. Any concentration of ClO2-could inhibited perchlorate degradation. Therefore, it was not detected during the process of Cl O4-degradating.The effect of dissolved redox mediators could promote perchlorate degradation andα-AQS was provided for the highest ClO4- reduction, followed by AQDS, 1,5-AQDS,2,7-AQDS, AQS and blank. α-AQS was the best redox mediator among them and could substantially catalytic accelerated ClO4-degradation process in its concentration range0.178~1.422 mmol·L-1, the temperature of 30℃, the pH range of 7.5 to 8.0. α-AQS could promote perchlorate degradation and slow down the inhibition of ClO3- to ClO4-. But it could not slow down the inhibition of ClO2-to ClO4-. The cyclic voltam Metry characteristics of redox mediators suggested that α-AQS had good redox activity, which benefited to its optimal acceleration effect.The effect of non-dissolved redox mediators could promote perchlorate degradation and1,5-Dichloroanthraquinone was the best redox mediator among them and could substantially catalytic accelerated ClO4- degradation process in its concentration of 0.036 mM, the temperature of 35℃, the pH of 7.5, the carbon(NaAC) concentration of 1.2g/L and the C/ClO4- ratio of 10:1. NO3- was benefical to the process of1,5-Dichloroanthraquinone promoting perchlorate degradation, but the effect of PO43- and SO42-was not obvious in the procss. ClO3-was a limiting step in ClO4-degradation, and this process had a little of accumulation ClO3-. 1,5-Dichloroanthraquinone maybe promote ClO2- degradation, and weakened the toxicity of ClO2- on chlorite dismutase. During perchlorate degradation, the pH and ORP value was kept in 7.2 to 8.0 and-420 mv.Meanwhile, the high redox activity of 1,5-chloroanthraquinone among five non-dissolved quinones was maybe the reason of its optimal acceleration effect.