Pilot-scale spiral wound membrane assessment for THM precursor rejection from upland waters

Area of Science:

• Environmental Science
• Water Treatment Technology
• Membrane Filtration

Background:

• Trihalomethanes (THMs) are disinfection byproducts in drinking water.
• Effective removal of THM precursors is crucial for water safety.
• Ultrafiltration (UF) and Nanofiltration (NF) are advanced membrane technologies for water purification.

Purpose of the Study:

• To evaluate the performance of commercial UF/NF spiral-wound membranes in removing THM precursors.
• To assess the impact of membrane pore size and selectivity on precursor removal efficiency.
• To correlate precursor removal with THM generation potential.

Main Methods:

• Pilot-scale filtration study using commercial UF/NF membrane elements.
• Analysis of surface water from a single source in Scotland.
• Measurement of dissolved organic carbon (DOC) passage and hydrophobic (HPO) fraction removal.
• Quantification of THM yield (weight % total THMs per DOC).

Main Results:

• NF membranes exhibited lower DOC passage than UF membranes, consistent with smaller pore sizes.
• Aromatic polyamide NF membrane showed the lowest DOC passage and THM yield.
• THM generation strongly correlated with the concentration of HPO fraction in the permeate (R² = 0.98).

Conclusions:

• Commercial UF/NF membranes are effective in rejecting THM precursors from surface water.
• Membrane selectivity and pore size significantly influence precursor removal efficiency.
• Reducing HPO fraction in permeate is key to minimizing THM formation in water treatment.