Energy Optimization in Membrane Bioreactors (MBR) Through Proper Design and Operations

Membrane Bioreactor (MBR) Systems for use in wastewater treatment is growing rapidly. Although superior effluent quality has been demonstrated for many years, there is still a popular belief that the high energy requirements of MBR Systems may preclude their use if the typical drivers are absent. MBR Systems are generally considered to be energy efficient at their capacity design points, but energy efficiency drifts higher as the capacity requirements move farther from the design point. The first step towards a more energy efficient MBR System is the evolution of the membrane units themselves. Current generation Submerged Membrane Units (SMU) are doing more with less, meaning reduced air scour requirements to sustain a proper biofilm at a given flux rate. Coupled with the evolution of the SMU is an overall systems approach to MBR design and operations. The goal of the system designer is to use only the required SMUs and associated equipment to treat a given flow, or flux rate, while at the same time maintaining proper system turndown to handle the varying influent flows most plants experience. This systems concept will keep the energy requirements consistent with the capacity requirements.