Study On Mechanism Of Strengthening Vanadium Removal Based On Bio-electrochemical System

With the toxicity increasing with the valence, pentavalent vanadium is the most toxic among all valence state of vanadium. Traditional vanadium method has the problem of large investment, poor removal effect, so there is an urgent need to develop a new processing method with high efficiency and low energy consumption. Nowdays bio-electrochemical system has been the research hotspots with combining biological method and electrochemical method.This study achieved the success of the effective removal of pentavalent vanadium and electricity generation by using microbial fuel cell technology and bio-electrochemical reactor respectively, based on the bio-electrochemical system improved the removal of vanadium with simulated wastewater containing pentavalent vanadium(V(V)) as an electron acceptor, and studied the mechanism and the pentavalent vanadium removal mechanism, influence factors. The results are as follows:The removal of pentavalent vanadium and electricity generation was achieved in a double chamber microbial fuel cell. The output voltage of 500~700 m V and maximum power density of 341.7 m W/m2 were realized in the dual chamber MFCs with influent pentavalent vanadium 100 mg/L. After the operation of 72 h, the removal rate of pentavalent vanadium was above 90%. At the same time, the amount of electronic anode produced by microorganisms is the limiting factor for generating electricity and reducing pentavalent vanadium.It was achieved to simultaneous anodic andcathodic reductions of vanadium(V) with energy recovery in microbial fuel cells by adding the pentavalent vanadium in the anode chamber, with greatly improving the removal efficiency of pentavalent vanadium. The output voltage of 420~460 m V and maximum power density of 418.6 ±11.3 m W/m2 were realized in the dual chamber MFCs with influent pentavalent vanadium 75 mg/L and 150 mg/L in anode and cathode respectively. Under the conditions of various combinations,the pentavalent vanadium in water was removed effectively. At the same time, this article researched the anodic microorganisms by molecular biological analysis, and found that the new generation Deltaproteobacteria and Bacteroidetes and the increased Spirochaetes play a major role in the removal of pentavalent vanadium. And it was verified that the final reduction product of pentavalent vanadium is tetravalent vanadium through the EDX and XPS technology.In this article, bio-electricity produced by microbial fuel cell, was used to strengthen the microbial reduction of pentavalent vanadium process, promote the removal of pentavalent vanadium. The influence of different factors(applied voltage, pentavalent vanadium concentration, COD concentration, conductivity) on the performance of the reactor were also studied. High-throughput 16 S r RNA gene pyrosequencing analysis implies the accumulated Enterobacter and Lactococcus reduce V(V) by consuming the products from fermentative microorganisms such as Macellibacteroides. The presentation of electrochemically active bacteria as Enterobacter plays a role in promoting electron transfers.This study combined firstly the electrochemical and biological reducing pentavalent vanadium, also expanded the scope of application of bio electrochemical system, and provided a reliable theoretical and experimental support for the practical application of the method.