The City’s Roadmap to Selecting a Membrane Bioreactor

As a part of the WRRF Project, the City needs to update their secondary treatment process. Secondary treatment includes removing ammonia and other pollutants using microorganisms. There are numerous methods to achieve this treatment level, so the team used the triple bottom line as their selection criteria. Based on economic, environmental, and social factors, the membrane bioreactor (MBR) was selected. The MBR provides the following benefits to the facility and the City’s ratepayers:

  • Reduces the need for additional treatment processes, therefore decreasing the amount of infrastructure required to implement.

  • Maximizes value as it positions the City for future potable reuse, while meeting existing water quality requirements.

  • Provides ultra-filtration that physically removes solids, resulting in a high-quality water that requires less energy to treat during UV disinfection.

  • Innovative yet proven technology.

  • Requires a smaller footprint, therefore conserving valuable “real estate” on site for future buildout.

In membrane filtration, the membrane pores are smaller than the microorganisms that provide biological treatment to the nutrient rich water and other materials, allowing only clean water to pass through the membrane.

The next step in the selection process was to learn about the different MBR suppliers. The City’s proactive approach to learning about the different MBR technologies on the market included the WRRF Operations and Maintenance staff every step of the way. These folks are the front-line staff who will eventually be responsible for the equipment, and including them was essential to determining the best product for the WRRF. The City and project team toured facilities to learn about different MBR systems, and to hear directly from the Operators about the systems’ performance.

As a result of their research and bidding process, the City has preselected Suez to supply the MBR system for the WRRF Project. Next steps for the project include incorporating Suez’s MBR into the design and preparing the drawings for construction.

Image credit: M brannock at English Wikipedia / CC-BY-SA-3.0 / Some changes made

© City of San Luis Obispo 2019