EFFECT OF FERMENTED WASTES ON DENITRIFICATION IN ACTIVATED-SLUDGE

Fermented organic wastes were investigated as electron donors for deni trification in activated sludge. Fermentation of primary domestic wast ewater sludge improved denitrification rates in nonacclimated activate d sludge, whereas fermentation of wastewater had no effect. In both ac climated and nonacclimated activated sludges, higher denitrification r ates were obtained with fermented sludges (from domestic wastewater or swine waste) than with either methanol or acetate. Methanol was equiv alent to acetate as electron donor for denitrification in acclimated s ludges but supported lower denitrification rates than acetate in nonac climated sludges. Mixing and pH were important determinants of volatil e fatty acid yields from organic wastes, whereas temperature in the ra nge of 28 degrees C to 35 degrees C had little influence.