Study On The Mechanism Of Reducing Of Bacaillus To The U, Mn, As Enrichment Plants

This paper aims at the key technical problems of how to deal with uranium and associated heavy metals enrichment plants,probing into the adsorption rate of U,Mn,As and weightlessness rate of straw under the decompose of Bacillus subtilis,Bacillus licheniformis and Bacillus cereus,and discusses the adsorption and mechanism of action of Bacillus subtilis,Bacillus licheniformis and Bacillus cereus to U,Mn and As in liquid nutrient medium,which provides a certain reference for the rapid reduction of super enrichment organisms by microorganisms.The main conclusions are as follows:(1)Bacillus subtilis,Bacillus licheniformis and Bacillus cereus can be effectively degraded the straw that contains heavy metals.In 15 days,the three kinds of bacillus made the straw loss weight 20.54% and the enrichment rate of U,Mn,and As was 28.43%、48.53%、45.43%.After adding the bacillus,the bacteria could enrich the heavy metals on the surface of the straw and destroy the fibrous structure of the straw.(2)When the initial concentration of UO22+ is 25~100 mg/L,Bacillus subtilis,Bacillus licheniformis and Bacillus cereus can grow normally,and enrich the uranium.The maximum adsorption rates of Bacillus subtilis,Bacillus licheniformis and Bacillus cereus to U were 86.09%,79.73% and 87.94%respectively.FTIR indicated that the adsorption sites of UO22+ were mainly hydroxyl,amine,carboxyl and bacterial proteins.And XPS showed that U(VI)is the main form of uranium adsorbed by bacillus.SEM and EDS showed that the cell surface of bacillus was rough,and uranium deposited on the surface and surrounding areas of bacillus.Therefore,uranium is adsorbed to the bacillus by hydroxyl,amino,carboxyl and other active sites,forms the precipitation of uranium on the surface,and with the microbial metabolism processes accumulation in the cell.(3)Bacillus subtilis,Bacillus licheniformis and Bacillus cereus can grow normally in Mn and As-containing medium and can enrich the Mn and As.The maximum adsorption rates of Bacillus subtilis,Bacillus licheniformis and Bacillus cereus to Mn were 76.21%、78.3%、82.02%.The FTIR results showedthat the adsorption sites of manganese were mainly hydroxyl,amine,carboxyl and other active sites.The maximum adsorption rates of Bacillus subtilis,Bacillus licheniformis and Bacillus cereus to As were 86.09%、79.73%、87.94%.And FTIR indicated that the adsorption sites of arsenic were mainly amide,hydroxyl,carboxyl and other active sites.(4)Under the 20~100 mg/L combined pollution with uranium,manganese and arsenic,Mn significantly inhibited the enrichment of U by Bacillus subtilis(r=-0.5235*).Mn significantly promoted the enrichment of Mn by mixed bacillus(r=0.7514**),and As significantly inhibited the enrichment of As by mixed bacillus(r=-0.5208*).