Nonlinear process control of anaerobic sludge digester

Abstract

Anaerobic absorption is a sequence of processes by which microbes separate decomposable wastes without oxygen. They convert the decomposable wastes in the form of carbon dioxide and water. Due to the nonlinear nature of the anaerobic process several control strategies are used to adjust the manipulated inputs to maintain the process outputs at desired set points. The objective of this work is to achieve the desired sludge temperature level of the anaerobic digester using PI (Proportional Integral), PID (Proportional-Integral-Derivative) Control and Fuzzy Logic Control (FLC). The comparative study indicates that the Fuzzy Logic Control is enhanced over conventional PID Control. The designed system can also be implemented using BFOA (Bacterial Foraging Optimization Algorithm) to optimize the operation and in tuning of PID controller parameters for an anaerobic digester.

Subject Classification:

• 93C10 Nonlinear systems in control theory
• 93B52 Feedback Control
• 93C42 Fuzzy Control/Observation systems
• 92B20 Neural Networks for/in biological studies

Keywords:

• PID Control
• Fuzzy Logic
• Fuzzy PID
• Substrate temperature
• BFOA