Model-based control of MF/UF filtration processes: pilot plant implementation and results

Abstract

Membrane micro- and ultrafiltration processes are widespread in water and wastewater treatment applications. Owing to the complex filtration mechanisms and the few available measurement information, they are typically operated using simple control approaches. However, two negative consequences are the sub-optimal performance and the relatively inflexible operation despite dynamic operating conditions. In previous publications, a model-based, adaptive run-to-run control approach for filtration processes has been introduced to improve process performance. It exploits the structure of cyclically operated filtration processes, where one cycle comprises a filtration and a backwashing phase. This contribution focuses on the experimental validation of the approach at a pilot-scale membrane bioreactor for municipal wastewater treatment. Necessary modifications to the approach and details on its implementation are discussed. The controller yields very good results with respect to prediction quality, optimization results, and stability. In addition to improved operational safety, savings of up to 50% are achieved with respect to energy consumption and membrane strain.