Low Flow Design for Membrane Bioreactors

Like many wastewater treatment systems, membrane bioreactors (MBR) frequently start up with flows well below design conditions and must continue to operate at low flows for extended periods of time. Low flow conditions are often overlooked during the design phase as a result of designers focusing on peak flow performance. However, controlling the performance of an MBR system at low flows is more challenging than controlling an MBR system at peak flows, especially if the system design does not account for low flows. Low flows can create operational challenges for equipment and ultimately lead to reduced effluent quality. This paper discusses the challenges related to design of MBR systems for low flow conditions and offers design methods to overcome these challenges. The Kuna, ID MBR system will be used as an example of the successful use of low flow design methods.