EFFECT OF FERMENTED WASTES ON DENITRIFICATION IN ACTIVATED-SLUDGE

Fermented organic wastes were investigated as electron donors for denitrification in activated sludge. Fermentation of primary domestic wastewater sludge improved denitrification rates in nonacclimated activated sludge, whereas fermentation of wastewater had no effect. In both acclimated and nonacclimated activated sludges, higher denitrification rates were obtained with fermented sludges (from domestic wastewater or swine waste) than with either methanol or acetate. Methanol was equivalent to acetate as electron donor for denitrification in acclimated sludges but supported lower denitrification rates than acetate in nonacclimated sludges. Mixing and pH were important determinants of volatile fatty acid yields from organic wastes, whereas temperature in the range of 28 degrees C to 35 degrees C had little influence.