A Hybrid Denitrification–Alternate Cycles Reactor To Enhance the Nitrogen Biological Removal in a Real Wastewater Treatment Plant

Abstract

This paper involves the retrofitting of a real municipal wastewater treatment plant (WWTP) of 6600 population equivalent (PE), from a traditional biological process to a predenitrificationalternating cycles (PreD-AC) technology, defining a hybrid reactor. The application was investigated for 11 months, from the upgrading in October 2009 to September 2010. The pro- cess optimization allowed to reach high standards of effluent's quality, with total nitrogen (TN) and ammonia (NH4-N) con- centrations lower than 15 and 1 mg L 1 , respectively. Moreover, the flexibility and automatic control of the process guaranteed an energy consumption decrease of17%, witha specificenergyconsumptionof0.18 kWhPETN 1 d 1 asan average value.Areduction of 20% was reached by comparing the sludge amounts disposed in landfills in 2009 and 2010.