An improved method of hydrogen production as electron donor for anaerobic bioremediation

This paper investigated an improved electrochemical approach that is able t o provide hydrogen for anaerobic bioremediation of chloroethenes in subsurf ace. Hydrogen is the ultimate electron donor of biodechlorination processes . In experiments, iron wire was used as electrodes, an anaerobic bacteria e nrichment collected from a site contaminated with chloroethenes as test mic robes, perchloroethylene (PCE) as model chloroethene. Experiments were cond ucted by switching the polarities of electrodes periodically and supplying electrical power in an intermittent way. The results showed that an electro chemical bioreactor that was switched 1 time/10 min and operated only 8 li a day was able to produce more hydrogen than that operated 24 h a day at 0. 4 V without polarity switching, stimulating microbial growth more effective ly. The intermittent operation also resulted in periodical release of overp otentials that built up on electrode surfaces, thus prevented charged ions and particles from attaching on electrodes. The hydrogen produced was avail able for microbial growth and PCE dechlorination. It is suggested that the improved electrochemical process developed in this study has significant im plications to anaerobic bioremediation.