Virus reduction through microfiltration membranes modified with a cationic polymer for drinking water applications

Virus penetration is a significant problem in water treatment membrane filtration. To effectively remove waterborne viruses nano-filtration, reverse osmosis or ultrafiltration must be used, all of which are high energy filtration schemes. Novel approaches and technologies for the production of virus-free drinking water are therefore warranted. In this study, we modified model surfaces and commercial polyether sulfone, (PES) microfiltration (MF) membranes to achieve a substantial virus reduction under gravity based filtration membranes. The successful modification using the cationic polymer polyethyleneimine (PEI) was confirmed by Fourier transform infrared spectroscopy (FTIR) and zeta potential measurements. MS2 bacteriophages, a surrogate for human pathogenic waterborne viruses like norovirus were used to challenge the modified surfaces. The membrane modification resulted in similar to 22% loss of the membrane permeability while an increase of >= 3 log(10)-units (>= 99.9%) in MS2 reduction was observed. These reductions were comparable to the reduction of PEI-coated model surfaces tested for contact reduction. This simple modification of a commercially available MF membrane led to substantial viral reductions with a significant flux of 5000 L/m(2) in approximately 2.5 h. This work therefore, highlights the potential modified MF membranes for gravity-based filtrations to produce safe drinking water. Further studies should be done to show similarly enhanced reductions of human pathogenic viruses.