NITRATE REDUCTION BY ANAEROBIC SLUDGE USING GLUCOSE AT VARIOUS NITRATE CONCENTRATIONS - AMMONIFICATION, DENITRIFICATION AND METHANOGENIC ACTIVITIES

A synthetic wastewater containing glucose as the sole source of carbon was used to assay glucose-acclimatized anaerobic digester sludge in b atch-tests for its potential to carry out ammonification (nitrate-->am monium), denitrification (nitrate-->nitrogen gas) and to continue anae robic digestion processes at various nitrate loads. Nitrate-->ammonium reduction activity was found to increase with decrease in the initial nitrate load. This activity appeared to take place principally during the acidogenesis of the glucose. Nitrate/nitrite loss after the ferme ntation process was essentially through denitrification. The denitrifi cation capacity of the anaerobic sludge used was very high. Up to 80% of added nitrate was denitrified. The presence of nitrate or nitrite e nhanced the fermentation of glucose to acetic acid but inhibited the p roduction of propionic acid and methane. This inhibition was not obser ved after the complete reduction of nitrate and nitrite.