(635a) Towards the Control of Fouling Behavior of Hollow-Fiber Membranes Via High-Throughput Screening

Hollow-fiber (HF) membranes are the preferred configuration for various water and wastewater treatment applications. The fouling of HF membranes is a complex phenomenon that is known to depend on a multitude of parameters and have a severe effect on membrane filtration performance. An ongoing challenge is the significant effort and time that is required to develop and test the effect of different operating parameters. We have recently developed a high-throughput (HT) platform for HF membranes [1] that allows for six filtration tests to be conducted in parallel with each test using a single HF membrane - this design is hereafter referred to as ‘high-throughput hollow fiber’ (HT-HF) module. As a proof of concept, preliminary experiments were conducted with un-modified polyvinylidene fluoride (PVDF) membranes in constant flux mode to evaluate the fouling tendency for different humic acid (HA) types and concentrations, solution conditions (pH, conductivity), and filtrate flux. It was observed that increasing the pH and decreasing the conductivity results in higher transmembrane pressures and lower apparent sieving coefficients. For example, the final transmembrane pressure (TMP) value decreased from 2.2 to 1.3 psi as the HA solution conditions were changed from 5% phosphate buffered saline (PBS) to 100% PBS while this change in solution conditions has increased the apparent sieving coefficient from 20% to 54%.

Furthermore, we have extended the application of the HT-HF module by performing experiments with a ‘library’ of potential foulants (humic acids, proteins, polysaccharides), testing different membrane pre-treatment and cleaning strategies, and using surface modified PVDF membranes. Surface modification of PVDF membranes have been studied by different groups in conventional format using different modifying agents such as polydopamine [2–4], polyvinyl alcohol [5], polyvinylpyrrolidone [6] and chitosan [7]. Furthermore, previous studies have shown the usefulness of developing a HT strategy to study the effect of surface modification on polyethersulfone flat sheet membrane performance using a monomer library in 96 well filter plate format towards natural organic matter [8] and protein fouling [9]. However, none of the previous works have studied the surface modification of HF membranes in HT format. In this study, PVDF HF membranes were modified using multiple approaches and modification conditions by using nanoparticles, polyelectrolytes and other polymers deposition in HT format using the HT-HF module. The modified membranes were characterized using contact angle measurements, Fourier transform infrared spectroscopy and scanning electron microscopy. The effect of surface modification condition on membrane hydraulic permeability, TMP profiles and separation performance were studied and the results were compared statistically to each other and to those of un-modified HF membranes. The HT platforms and the results introduced here will be used to develop new strategies for controlling membrane fouling and to better understand membrane fouling behavior.

References

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