The Movement and Electric Injection of Two Strains of Microorganism in Soils Under Uniform Electric Field

XU Wei,WANG Cui-ping,ZHANG Zhi-yuan,LIU Hai-bin,SUN Hong-wen(MOE Key Laboratory on Pollution Processes and Environmental Criteria,Nankai University,Tianjin 300071,China)

electric injection;microorganism movement;pH value variation;electrokinetic bioremediation

Active microorganisms are the primary factor controlling the effieciency of bioremediation of sites contaminated by organic pollutants.Electrokinetic provides a new way to inject mocroorganisms into target sites.In this study,the movement of Bacillus subtillis and Phanerochaete chrysosporium in a soil under uniform electric field and the electric injection of the two microorganisms were studied.The two microorganisms could be transported effectively into the soil by the electrokinetic injection.They moved in electric field driven by both electroosmosis and electrophoresis.The electroosmotic flow rate was 26 mL·d-1 under voltage gradient of 1 V·cm-1.The two microorganisms migrated mainly to anode driven by electrophoresis.The migration velocities were 13.5 cm·d-1 to the anode and 7.5 cm·d-1 to the cathode for B.subtillis in the studied soil,and 18.0 cm·d-1 to the anode and 9 cm·d-1 to the cathode for P.chrysosporium.Compared to changing the electric direction,keeping the electric field in the same direction led a more even distribution of the microorganisms.With the circulation pattern,the acidity and alkalinity generated by electrolysis of water molecule in electrode solutions were neutralized,thus pH in soil did not change dramatically,ranging between 7.0 and 7.6 in the tested soil.The neutral pH provide a suitable condition for the survival of microorganisms.This study provides necessary data for the set-up of electrokinetic bioremediation for sites contaminated by organic pollutants.