Fuzzy Controller Design And Simulation Of SBR Wastewater Treatment Process

According to the shortage of freshwater both with the enhancement of environment protection, the importance of wastewater treatment is becoming more and more obvious. The Activated Sludge Process, as a kind of wastewater treatment method which is most commonly used, is a artificial strengthened method on self-purification of water body. In the activated sludge, with the removal of contaminants, the composition of sludge, the variety and numbers of microorganism and the dynamic parameters indicating its reaction, and the volume and density of water are all varying, so it's very difficult to establish a precise mathematics'model, and also the control can't be well fulfilled by classic control theory and modern control theory.SBR, a kind of activated sludge process, has been investigated deeply and applied widely in recent years due to its unique technical characteristics. The automatic control of SBR, which determines the potential for its application, has always been the focus of people's attention and academic research. Now, the method usually adopted in practice is the timing control based on 5 steps of SBR. But the defects of the timing control is that it can not realize online control of reaction process and time according to the actual volume and density of waste water, resulting in processed water failing the standard and sludge expanding. With the improvement of automatic control theory and technology, the transformation from automatic control to intelligent control needs to be worked out. Fuzzy control, as a branch of intelligent control, can translate monitors'or experts'knowledge and experiences into control rules, which will be used to control system. Therefore, fuzzy control is typically suitable for the control of unknown mathematic model and complicated non-linear system. Based on these characters, this essay proposes to apply fuzzy control to the control of dissolved oxygen in SBR, in order to improve the efficiency of waste water treatment, decrease energy consumption and evade sludge expanding.The main study of dissertation is following:â‘ Through analyze the current application status of fuzzy control in the waste water treatment, and point out the viability of fuzzy control in the SBR treatment processâ‘¡suggest the fuzzy control strategies of SBRâ‘¢based on the characters of SBR, apply fuzzy control to the control of dissolved oxygen in SBR, design fuzzy controller and finally by MATLAB simulation, verify the adaptability of applying the fuzzy control to dissolved oxygen control in SBR.