Optimizing Membrane Bioreactor/ Reverse Osmosis Performance for Municipal Wastewater Treatment

Abstract

Combining microfiltration (MF) and reverse osmosis (RO) is an accepted practice for treating secondary effluent to allowable levels for common and advanced reuse applications. Several municipalities in the United States and abroad use this combination on a large scale. This leads to the next innovation in treating wastewater—membrane bioreactors (MBRs), the specialized use of MF integrated with activated sludge treatment followed by RO. The Southern Nevada Water Authority has been conducting an ongoing test of such a configuration at the Las Vegas Water Pollution Control Facility since 2009. The study's goal is to better understand the fouling of RO membranes, which directly treat MBR effluent, and to evaluate technologies to minimize RO fouling. The pilot has had stable operation for more than 4,000 hours and has not required RO cleaning when operated at a flux rate of 14 gpd/ft² (23.8 LMH) and higher. The results have confirmed that MBR–RO is a viable wastewater treatment technology.