          109      !"#$%& ’() " &%%) *&*&% %&#&+ ,) !"#$’&% #’-"+ Stefania Iordache 1 , Nicolae Petrescu 1 , Cornel Ianache 2 1 Faculty of Environmental Engineering and Biotechnology Valahia University of Târgovişte, Regele Carol I, nr 2,130024, Târgovişte, Romania 2 Faculty of Electrical and Mechanical Engineering, „Petroleum+Gas” University of Ploieşti, 39, Bucureşti Blvd, Ploieşti, 100680, România E+mail: stefania.iordache@yahoo.com  The aim of this work is to asses conditions for implementation of a Biological Nutrient Removal (BNR) process in the Wastewater Treatment Plant (WWTP) of Moreni city (Romania). In order to meet the more increased environmental regulations, the wastewater treatment plant that was studied, must update the actual treatment process and have to modernize it. A comparative study was undertaken of the quality of effluents that could be obtained by implementation of biological nutrient removal process like A2/O (Anaerobic/Anoxic/Oxic) and VIP (Virginia Plant Initiative) as wastewater tertiary treatments. In order to asses the efficiency of the proposed treatment schemata based on the data monitored at the studied WWTP, it were realized computer models of biological nutrient removal configurations based on A2/O and VIP process. Computer simulation was realized using a well+known simulator, BioWin by EnviroSim Associates Ltd. The simulation process allowed to obtain some data that can be used in design of a tertiary treatment stage at Moreni WWTP, in order to increase the efficiency in operation. . : process simulation, biological processes, nutrient removal, wastewater.  +%"(’!"+   + / /  With the aim to prevent eutrophication process, the maximum nutrient (Nitrogen and Phosphorus) concentrations of treated municipal wastewater are restricted by European regulation. The limit values of specific indicators regarding nutrient concentrations are presented in the Urban Wastewater Treatment Directive 91/271/EEC[3]. In order to improve Nitrogen and Phosphorus removal, existing wastewater treatment plants (WWTP) have to be updated by inclusion of a a step for biological nutrient removal, according with the Directive limits. The process of nutrient removal from urban wastewater can be achieved by biological treatment, which was studied by a lot of different authors during the past years [1,2,5,6,7,16]. Nowadays, Biological Nutrient Removal (BNR), is a very well known process and is usually achieved by activated sludge processes with selected anaerobic, anoxic and aerobic conditions [6]. In the past decade, a number of enhanced biological phosphorus removal (EBPR) processes have been developed [9]. EBPR is a modified activated sludge process in which an initial anaerobic unit followed by an aerobic cycling of the activated sludge results in the production of biomass of higher than normal phosphorus content. [9,10,11]. Due to more stringent regulations for secondary municipal wastewater treatment, municipalities are beginning to implement tertiary treatment in their wastewater treatment plants [7]. Tertiary treatment involves removal of either phosphorous or nitrogen or both from the wastewater before it is discharged in a water body. Nowadays, in Romania, biological treatment became an increasingly popular process used to accomplish the nutrient removal from wastewater [8]. There are several processes available that can provide acceptable levels of biological nutrient and BOD removal from wastewater[7].