Columnar denitrification of a munitions waste

Abstract

The removal of nitrate nitrogen from a munitions waste by means of bacterial reduction was investigated using packed anaerobic columns. The feasibility of using a munitions waste high in organic carbon (Water Dry Process Waste) as the organic carbon source was also investigated. Simultaneously the biological processing was accomplished in two manners, anaerobic packed columns and batch anaerobic vessels.

It was found that anaerobic columns were effective in reducing 100 mg/l nitrate nitrogen by as much as 99.9% operating at an empty column detention time of 8.76 hours. No difference in denitrification capacity was found between columns packed with activated carbon or sand, but the activated carbon was found to be an undesirable media because of its low specific gravity which permitted it to float after gasification began, and because of foul-smelling odors associated with the activated carbon effluent. The Water Dry Process Waste was found to be a suitable organic carbon source for denitrification and it had a consumptive ratio of 1.47. Batch vessels were found to be ineffective in significantly reducing total nitrogen over a period of 46 days. Buildup of high concentrations of nitrite within the vessels suggested inhibition of the biomass to an extent that further denitrification would not occur.