Realization of Simultaneous Nitrification and Denitrification via Nitrite by Controlling Sludge Age

Nitrogen removal from synthetic municipal domestic wastewater was studied using the sequencing batch reactor(SBR) activated sludge process.Simultaneous nitrification and denitrification via nitrite was successfully realized through controlling sludge age.Experimental results show that for optimal sludge age,the ratio of NO-2-N to NO-x-N remains above 84.48% throughout the aeration phase,and 80.39% of ammonia is removed by simultaneous nitrification and denitrification during the end of the aeration phase.Under the feasible DO concentration,maintaining optimal sludge age by draining the mixture of activated sludge and wastewater at normal temperature can result in a stable simultaneous nitrification and denitrification via nitrite.