FLEWR Study Could Lead to Customer Benefits Through Reduced Operating Costs
The Filter Loading Evaluation for Water Reuse (FLEWR) is a systematic approach to determine the effect on recycled water quality of varying filter loading rates — and as influenced by other routinely monitored plant performance parameters.
Data obtained from pilot filters in Phase 1 indicated that a higher loading rate is capable of producing acceptable quality tertiary recycled water, resulting in a significantly higher throughput with the same filtration facilities.
The filtration system employed at Monterey Regional Water Pollution Control Agency water recycling plant was typical of many of the 250-plus tertiary filtration systems in use in California. Thus, a scientific basis for an acceptably higher filter loading rate may assist other agencies’ ability to increase their water recycling capacities with minimal additional investments.
 The UC Berkeley Connection
One of the evaluation requirements is that FLEWR be an academic study, that a graduate student lead the project and that the results be published. Gordon Williams, a PhD candidate at UC Berkeley, is that person. He is shown at right collecting water samples during Phase I to test for pathogens at the pilot plant he helped design and build.
Phase 2 Begins
In May, the California Department of Health Services Water Quality Control Board gave the go-ahead for Phase 2. “It took a long time to acquire the waiver,” states MRWPCA Engineer Tom Kouretas. “After Phase 1, at the beginning of 2006, there was much paperwork to take care of, including a complete engineering report on the treatment plant.”
And then there was the preparation. “We couldn’t just start running 50 percent more influent — 7.5 gallons per minute per square foot instead of 5 gallons — through the filters,” Tom notes. “We had to install additional equipment, such as particle grinders on Filter 6, the test filter.”
In July, the first set of 10 runs began. “The filters seemed to respond well,” Tom says. “After each set, we’ll do a quick analysis of the data here then send it off to UC Berkeley for more extensive analysis. We’re looking at the percentage of difference in water quality, turbidity and particle counts. What the differences are will determine how many runs of 10 we do. After each run, we’ll tighten things up — to help achieve the desired results.”
Operations and Lab Performing Essential Roles
“Virtually everyone in Operations has had a role in Phase 2,” Tom says, “and they’ve been working really hard.”
The Plant Operators strictly control the flow to Filter 6. “As an added perk for the Agency, they can also time it so that the higher rate runs during peak influent times, thus allowing us to capture more wastewater for recycling,” Tom states.
“Everyone in Operations has been quick and well focused,” states James Dix, “from making chemical adjustments to Filter 6 to grabbing samples several times per shift and recording what’s going on with the filter.”
 In the Lab, Jackie Dhlos and Angelica Lopez (pictured at right), along with Supervisor Patrice Parsons and Sylvia Burnett, handle the total coliform and E coli testing. “During the first runs, there were adjustments to be made to ensure our results were good,” Patrice notes. Jackie adds that “Some bacteria have to be read at 24 and 28 hours, so, depending on when the samples come in, we can wind up monitoring them in the evenings or on weekends.” There haven’t been any objections to the unusual work routine, according to Sylvia. “We all recognize that this is an important project.”
FLEWR Goes Statewide
The FLEWR pilot study was conducted solely at the MRWPCA treatment facilities. For Phase 2, additional agencies are participating:
- City of Santa Rosa
- City of San Jose
- Los Angeles County Sanitation Districts
- West Basin Municipal Water District
- Delta Diablo Sanitary District
- Inland Empire Utilities Agency
Additional Information
http://www.coe.berkeley.edu/forefront/images/spring2005.pdf
http://www.coe.berkeley.edu/forefront/spring2005/nelson.html
http://www.bahmansheikh.com/pdf_files/papersheikhetal.pdf
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