Acta Universitatis Sapientiae Agriculture and Environment, 1 (2009) 38-45 38 Adaptating dynamic simulation to a wastewater treatment plant reconstruction Endre DOMOKOS 1 , Viola SOMOGYI 1 , Ákos RÉDEY 1 , T. YUZHAKOVA 1 1 Institute of Environmental Engineering, University of Pannonia, Hungary e-mail: domokose@uni-pannon.hu e-mail: somogyiv@uni-pannon.hu e-mail: redeya@almos.uni-pannon.hu e-mail: yuzhakova@uni-pannon.hu Manuscript received 30.07. 2009; revised 20.08. 2009, accepted; 25.08.2009 Abstract: The examined municipal wastewater plant was designed for 100,000 population equivalent (PE) and which was previously operating as a total oxidation system. The management wanted the plant to perform denitrification and excess phosphorus removal out of economical and environmental reasons. In this study the reconstruction plan created by the company was examined with the help of modeling software. On behalf of this the plant would function well during the summer, but at low water temperature (15°C) the expected results would not be met. Therefore the authors, after further calculations, suggested a new scheme. Keywords: nutrient deficiency, phosphorous removal, modeling 1. Introduction The wastewater treatment plant was working in the same structure since 1994. It was designed for a daily load of 48,000 m 3 . The plant consists of three primary settlers with a total volume of 2270 m 3 , four aerated reactors 3000 m 3 each and four secondary settlers (2750 m 3 each) operating in parallel mode. The annual rate of flow of 2003 (Figure 1.) shows that in most of the year the input of the plant was around 21,000 m 3 /day and even in the processing period of the preserving factory it did not go over 23,000 m 3 /day. The daily fluctuation was of greater influence. This derived partly from the cyclic changes in processing and in the rate of the municipal flow, partly from the function of the feed pumps. The changes of a typical summer day are shown on Figure 2.