Active control optimization for anaerobic digestion processes

• Published in: Desalination and water treatment 2019-01, Vol.138, p.200-207
• Main Authors: Phuc, Bui Duc Hong, You, Sam-Sang, Nam, Nguyen Ngoc, Kim, Hwan-Seong
• Format: Article
• Language: English
• Subjects: Anaerobic digestion; Chemical oxygen demand; Observer; Robust control; Volatile fatty acid
• ISSN: 1944-3986; 1944-3986
• DOI: 10.5004/dwt.2019.23331

Anaerobic digestion is currently the most popular process for renewable energy by collecting biogas from organic degradable materials. The main barriers include significant changes in the input composition, external disturbance, and the high cost and complexity of the analyzing system. In this paper, after some nonlinear analyses, the observer-based robust controller is designed for the linearized system to replace the limitations of conventional controllers dealing with those problems. The chemical oxygen demand concentration and dilution rate are selected as controlled and manipulated variables, respectively. The volatile fatty acid is the system state to be estimated, providing that there is no sensor to analyze this composition. The simulation results show that the achieved controller can regulate chemical oxygen demand concentration under large disturbances and plant uncertainties as well as can exactly estimate the volatile fatty acid. Applying this approach can help to increase the robustness of anaerobic digestion processes and to reduce the investment cost by replacing some expensive sensors.