From the same wbsite, I find the alternative rather interesting...
Hydrogen can be used as a nitrate scavenger in the presence of a catalyst. The best results were achieved with a palladium catalyst; 99.9% of nitrate was reduced to nitrogen and only 0.1% formed ammonia (Horold, S.; Vorlop, K. D.; Tacke, T; Sell, M. Catal. Today1993, 17, 21-30). The drawback is that the catalyst is sensitive to poisoning by the presence of heavy metals. The process has been tested only at low concentrations of nitrate.
so what is palladium catalyst...
what if the we can feed the remaining ammonia to the readily available bacteria?
...low concentrations of nitrate.... hmmmm.