Engineering, 2010, 2, 820-831 doi:10.4236/eng.2010.210105 Published Online October 2010 (http://www.SciRP.org/journal/eng) Copyright © 2010 SciRes. ENG A Fast Predicating of Nutrient Removal Efficiency in Five Steps Sequencing Batch Reactor System Using Fuzzy Logic Control Model Saad Abualhail 1 , Rusul Naseer 2 , Ammar Ashor 3 , Xi-Wu Lu 1* 1 Department of Environmental Science and Engineering, Southeast University, Nanjing, China 2 Department of Chemical Engineering, Faculty of Engineering, Basrah, Iraq 3 Department of Civil Engineering, Faculty of Engineering, Basrah, Iraq E-mail: saad.arab@yahoo.com Received June 10, 2010; revised August 4, 2010; accepted August 6, 2010 Abstract Removal efficiency of COD, NH4-N and PO4-P and NO3-N in five step SBR processes is widely influenced by hydraulic retention time of Anaerobic/Anoxic/Aerobic/Anoxic/Aerobic step of this system where the hy- draulic retention time in each step is influence directly on removal efficiency of this system therefore the op- erator of this system cannot control on this system without experience or a control model. The major objec- tive of this paper is develop a control model (Fuzzy Logic Control Model) based on fuzzy logic rule to pre- dict the maximum removal efficiency of COD,NH4-N,PO4-P and NO3-N and minimize hydraulic retention time in each step of SBR process where the controlled variables was the hydraulic retention times in the An- aerobic/Anoxic/Aerobic/Anoxic/Aerobic step respectively and the output variables was the COD, NH4-N, PO4-P and NO3-N removal efficiency at constant ratio of C/N/P and sludge age. As a results Fuzzy logic if-then rules were used and MIMO Model was built to control COD, NH4-Nand PO4-P and NO3-N removal efficiency based on hydraulic retention time in each tank of five step SBR process where the three dimension results show that the influence of hydraulic residence time at each step of SBR system on removal efficiency COD, NH4-N, PO4-P and NO3-N. Fuzzy control model provide a suitable tool for control and fast predict of Hydraulic residence time effects on biological nutrient removal efficiency in five-step sequencing batch re- actor. Keywords: Fuzzy Logic Control, Hydraulic Retention Time and SBR System 1. Introduction Conventional control methods are powerful when good analytical mathematical models are available to support their development and operation. This situation is un- common in real processes. Particularly, the real-time control of wastewater treatment plants (WWTP) is a dif- ficult but essential task, due to the lack of accurate dy- namical models describing the process and reliable on -line instrumentation (Olsson and Newell, 1999). How- ever, WWTP can be properly operated by specialized peo- ple, having knowledge about the process, though in prac- tice, this know-how is essentially qualitative, empirical, and incomplete. The operation of a WWTP represents therefore a knowledge intensive task. In this regard, a system capable of giving all the possible information about the state of the process must be available in order to establish the basis of a diagnosis system integrating all the possible knowledge. This requirement is an important step to have successful control. Decisions(Patry and Chapman, 1989). Applications of knowledge-based systems to activated sludge processes are being widely studied (Chapman et al., 1989, Barnett et al., 1992). Most of systems are off-line Knowledge- Based Expert Systems (KBES) mainly diagnostic and advising tools to help process Operators. An activated sludge wastewater treatment plant can be classified as a complex system due to its nonlinear dynamics, large un- certainty in uncontrolled inputs and in the model pa- rameters and structure, multiple time scale of the dy- namics, and multi input-output structure. Some KBES *Corresponding Author: Xi-Wu Lu, Southeast University