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The City of Riverside (City) is currently constructing the largest Membrane Bioreactor (MBR) retrofit in the United States as part of the $200 million Regional Water Quality Control Plant (RWQCP) Phase 1 expansion project. The City evaluated the total cost of MBR ownership and membrane system supplier experience and selected GE/Zenon Environmental Corporation (GE) in July of 2010 as providing the best overall value. Initially the City selected GE/Zenon to supply their "10/30 Eco-Aeration Design" system. In July 2011 at the time of the project's 100 percent design submittal, GE released the LEAPmbr system. The City had to decide if the risk of applying the new technology were acceptable. The City decided that the savings in construction cost and energy were worth the risk and delays of implementing the new system. The board approved the change in the system.

Tertiary treatment has become widespread in wastewater treatment plants, both to meet discharge standards for receiving water and to provide influent for advanced water treatment in arid regions. There are many approaches to tertiary treatment depending on the contaminants to be removed, and as a result, there are a wide variety of tertiary unit processes in operation around the world. The long-term success of these systems requires effective approaches for rehabilitation and operational optimization. In this study, the City of Los Angeles Bureau of Engineering, MWH, and Lee and Ro investigated the tertiary granular media filters at the Terminal Island Water Reclamation Plant in San Pedro, CA, to determine the causes of various operational issues and consider potential rehabilitation. It was discovered that the design and operation of the filters had several inconsistencies. The rehabilitation of the filters focused on resolving the identified issues and inconsistencies. Issues encountered included significant media loss, leaking valves, underdrain block failures, and inconsistent design elements built into operation of the filter.