DUKE ENERGY

In 2017, BKT piloted a new anti-fouling membrane treatment technology for FGDW at a 2,240 MW power plant. Trade-named FMX, the system uses rotating blades to create hydraulic vortices at the membrane surface, preventing the fouling and scaling experienced by conventional membranes. The pilot treated 5,000 gal/d using a membrane surface area of 54.5ft2 to compare FMX removal performance to an existing membrane bioreactor (MBR). Over 3 months of treatment, Se influent concentrations ranged from 71-697ug/l (mean 200ug/l). FMX achieved 61% average Se removal with min 47% and max 85% removal. Average removal for other target pollutants were 74%, 94%, and 35% for As, Hg, and NOx, respectively. Influent concentrations were 10mg/L for As, 51ng/L for Hg, and 24mg/L for NOx. FMX achieved an average flux of 61 gal/(ft2∙day) with negligible scaling/fouling observed. FMX effluent was able to meet the US EPA’s BAT and BADCT treatment standards for FGD discharge (2015 rule 40 CFR Part 423) but was not able to guarantee adherence to Se and NOx limits without downstream membrane processes. BKT is now testing a smaller pore membrane with a MWCO of 200Da intended to guarantee single-stage adherence to revised EPA standards.

Test overview

•Testing took place at the Duke Energy Belews Creek Power Station from April 30th – July 30th 2017

•The FMX system was used to treat the FGD feed pre-treated by Evoqua’s selenium reduction process using membrane NF-270

•Permeate generated from the FMX membrane system was returned back to the system for reuse and reject (concentrate) was collected to be used in a test bed to produce concrete

•Feed, FMX Permeate, FMX Concentrate were collected for each week and sent out for analysis to Duke laboratory

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Client Goals and Test Results Summary

1. Client Goals
   The main goal of this onsite test is to collect 50,000 gallons of concentrated brine

2. Challenges
    Changing influent wastewater characteristics

3. Expectation on FMX
    FMX can produce enough concentrated brine without major issues, such as clogging, membrane damage or fouling

4. Test Results Summary
    The FMX system was able to generate 50,000 gallons of concentrated brine without major issues
    Of 184 documented batches, the FMX showed 30-60% of rejection with an average of 44.4% rejection of TDS
    Average Flux 88 LMH (51 GFD)

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fmx benefits

  1. Analytical analysis of TDS shows a consistent rejection rates for Mercury, Lead, Arsenic, Sulfate, Selenium, and Zinc.
     
  2. High flux figures and low CIP intervals indicate that fouling and scaling of the membrane surface is kept to a minimum with FMX technology.
 

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