Denitrification of groundwater with methane as sole hydrogen donor

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