Real-Time Membrane Fouling Monitoring


The Port Hueneme Water Agency (PHWA) has been operating a municipal drinking water treatment plant designed to be a Brackish Water Reclamation Demonstration Facility. The facility consists of 3 separate side-by-side full scale systems or trains, each representing a major membrane separation process: nanofiltration (NF), reverse osmosis (RO) and electro dialysis reversal (EDR). Both the NF and RO trains use semipermeable spiral-wound thin-film polyamide membranes, manufactured by Dow Filmtec, that selectively allow water to pass but not most dissolved salt ions.

In order to monitor the plant’s operation, PHWA relies on a combination of IntelleutionFix data and reports generated by the facility’s SCADA data acquisition system. Membrane system performance is being monitored daily using Dow Filmtec’s ROSA software program and a set data normalization procedure. Plant operators inputted the flow set points and water quality analysis data into the original ROSA configuration. They used the expected fouling factor of 1.0 and the set points for flows as published by Filmtec. Each day, the operators take the average analog values for flows, pressures, and conductivities, and enter them in an Excel spreadsheet with 'macros' back to the ROSA configuration file. That gave them the ability to request trending graphs of normalized flow, differential pressure, salt passage, and salt rejection . Of these, the normalized flows and differential pressure graphs in particular are utilized to monitor the system’s health. Daily and monthly performance reports generated by PLWeb, are available to the public on-line.

Design and operating data from RO Train A and NF Train A were recently provided by PHWA for evaluation using a new, early-warning membrane performance and fouling monitoring technology and software system known as MASAR ( Membrane Analysis System and Automated Reporter), developed recently by MASAR Technologies, Inc. of Tucson, Arizona. A unique parameter, known as the Fouling Monitor, or FM, is measured and used by MASAR software to monitor the membrane systems performance of RO, NF, UF and MF water purification plants. The industry-standard normalization method (ASTM D-4516-00, “Standard Practice for Standardizing Reverse Osmosis Performance Data”) has been utilized by all membrane manufacturers and water plant operators to produce a long-term flux decline performance trend by comparing the normalized product flux and quality performance to design projections under the same conditions. The FM, on the other hand, is based on detecting and quantitatively measuring membrane fouling or scaling as soon as it starts to develop in the system in real-time, eliminating the need for long-term, ambiguous trending analysis.

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