Denitrification of groundwater with methane as sole hydrogen donor

It was examined, whether methane call be used as hydrogen donor for an in s itu denitrification of groundwater. It is demonstrated, that groundwater ca n sen e as liquid medium and that the denitrification can occur at 10 degre esC. Efforts to enrich methanotrophic bacteria under anoxic conditions have not been successful. No methane oxidation occurred in the absence of oxyge n. For this reason, the denitrification with methane must be performed in a two-stage process with aerobic methanotrophic bacteria producing metabolit es, that are used as hydrogen donor by non-methanotrophic bacteria in anoxi c areas. This kind of indirect denitrification was proved by quantifying ni trogen and nitrous oxide in enrichment cultures that were not stirred or sh aken, Large numbers of non-methanotrophic bacteria being able to denitrify with methanol, acetate or proteins as sole hydrogen donor were enriched bes ides the methanotrophic bacteria under these conditions. (C) 2001 Elsevier Science Ltd. All rights reserved.