Discussion/Findings
This Method has provided decent preliminary work to help explain Ca organic fouling phenomenon and the influences that different anions have on the system, but needs further work to develop a method that provides more accurate and precise results (higher spike recoveries and lower QRSD).
Future work for Experiments:
- Use more accurate calibration range for Na (1-100 ppb)
- Digest a larger quantity of the membrane sample
- Use a second more dilute sample for calcium analysis to reduce matrix effects
- Running a Standard Addition Method if needed
- Use QC samples that are closer in concentration to the unknowns
These preliminary results show that the ion pairing interactions with Ca can greatly impact organic fouling. When ion pairing increases between the Cl, NO3, and SO4 experiments less free Ca can interact with the organic matter, threshold flux increases, and the Ca concentration on the membrane decreases. However, the interactions between the ion-paired species and the organic matter can have a more profound impact on the fouling behavior. While acetate and CO3 ion-pair less than SO4 they both increase threshold flux due to the anion capping the Ca interacting with the organic matter, reducing the amount of bridging that occurs while increasing the total Ca in the fouling layer.
Future work for Experiments:
- Performing triplicate fouling experiments for statistically relevant
- Threshold fluxes and
- Membrane surface concentrations (fouled and pristine)
- Organic Analysis
- Total Organic Carbon Analysis on feed samples
- Size Exclusion Chromatography (SEC) on feed samples
- Ion Chromatography on feed samples
- Inorganic Carbon Analysis on CO3 feed sample
- Fluorescence Spectroscopy on feed samples and membrane surfaces
- Fourier Transformed Infrared Spectroscopy (FTIR) on feed samples and membrane surfaces