Comparative study of methanol, butyrate, and hydrogen as electron donors for long-term dechlorination of tetrachloroethene in mixed anaerobic cultures. Biotechnol Bioeng 91(6):743–753

Abstract: This study examined the ability of different electron donors (i.e., hydrogen, methanol, butyrate, and yeast extract) to sustain long-term (500 days) reductive dechlorination of tetrachloroethene (PCE) in anerobic fill-and-draw bioreactors operated at 3:1 donor:PCE ratio (defined on a total-oxidation basis for the donor). Initially (i.e., until approximately day 80), the H2-fed bioreactor showed the best ability to completely dechlorinate the dosed PCE (0.5 mmol/L) to ethene whereas, in the presence of methanol, butyric acid or no electron donor added (but low-level yeast extract), dechlorination was limited by the fermentation of the organic substrates and in turn by H2 availability. As the study progressed, the H2-fed reactor experienced a diminishing ability to dechlorinate, while more stable dechlorinating activit