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Determination of Rate and Order of Denitrification of Nitrified Effluent without Organic Carbon using Activated Sludge

Authors : Roumi Bhattacharya and Debabrata Mazumder



Denitrification studies of synthetic nitrified effluent were performed in laboratory scale batch activated sludge process to examine the effect of absence of organic carbon on denitrification. The orders of the reaction under two conditions of organic carbon content were determined and relevant rate constants were evaluated from the experimental data. During the study, maximum nitrate removal of 92% and 54% was achieved in case of denitrification using methanol and without using methanol respectively under a nitrate to biomass concentration ratio of 0.1. Zero order reaction kinetics was observed to be the best fit for all the studies. The maximum specific denitrification rates were observed to be 11.93±5.13 and 9.46±1.56 mg nitrate/g MLSS/h respectively in presence and absence of methanol. The maximum denitrification rate was attained, when methanol was added
@ 1.9 times of nitrate concentration under a nitrate to biomass ratio of 0.2. In presence of sufficient biomass in a reactor, limited supply of readily available organic carbon facilitates endogenous metabolism and addition of external carbon may be reduced, thus economizing the process.
Nitrate profile for denitrification with methanol and at nitrate to biomass ratio 0.1













Denitrification, nitrified effluent, organic carbon, order of reaction, specific denitrification rate