AERATION DIFFUSER MEMBRANE TESTING AT THE SONOMA VALLEY TREATMENT PLANT

Following successive aeration diffuser membrane failures at the Sonoma Valley Treatment Plant (SVTP), the plant operations and maintenance staff performed in-situ materials testing and evaluations to determine the best readily-available membrane material for a permanent replacement.The methodology used for testing was to place three identical groups of various diffuser membrane materials in service within one aeration basin for an extended period of time while holding an identical control group in storage. Following the in-situ test period the diffusers were removed and evaluated for signs of degradation. The materials evaluation was performed by comparing each diffuser membrane from one test group with its corresponding unused control membrane visually and with aeration pattern and water flow tests.A materials viability matrix was created from the evaluation data along with cost and maintenance considerations. Verification retesting of the two most viable materials was conducted using all three test group diffusers and the most viable material was selected.Reference interviews of plant personnel using the selected membranes were conducted and an application evaluation for fitting the selected membranes onto the existing diffuser bodies was performed prior to procurement and installation.