The Greenfield Clovis WRF MBR Design: Theory Versus Reality

The City of Clovis, California, started up a state-of-the-art water reuse facility (WRF) in 2009 that reduces the City's dependency on groundwater and provides for future wastewater treatment needs. The new facility has the capacity to produce an average of 2.8 mgd and will meet California's stringent Title 22 reuse requirements.Greenfield design of wastewater treatment plants includes significant risks that the influent and plant operation will not be as predicted. During the design process a thorough analysis of alternatives that took into consideration the track record of successful use, beneficial use of residuals, footprint, energy use, and cost, MBR's were chosen for the main liquid process in combination with Siemens Cannibal™ process for solids handling and UV for disinfection. The selected processes provide a high quality Title 22 effluent while minimizing the production of residuals while providing a robust solution deal with uncertainties.The Clovis WRF has indeed shown that influent quality is significantly different than predicted, but the MBR process has been able to accommodate the differences without adverse effects on the plant. Of particular note was the ability to operate at lower DO levels than planned, thus reducing energy usage and improving total nitrogen values, which is directly attributable to the long SRTs produced by the Cannibal solids reduction process. Lastly, the UV transmittance of the MBR effluent has been much higher than predicted, thus allowing the UV system to almost continually run at it's lower power settings and achieve the needed disinfection goals.