Study on the removal efficiency of UF membranes using bacteriophages in bench-scale and semi-technical scale

Abstract

To determine the removal efficiency of ultrafiltration (UF) membranes for nano-particles in the size range of viruses the state of the art uses challenge tests with virus-spiked water. This work focuses on bench-scale and semi-technical scale experiments. Different experimental parameters influencing the removal efficiency of the tested UF membrane modules were analyzed and evaluated for bench- and semi-technical scale experiments. Organic matter in the water matrix highly influenced the removal of the tested bacteriophages MS2 and phiX174. Less membrane fouling (low ΔTMP) led to a reduced phage reduction. Increased flux positively affected phage removal in natural waters. The tested bacteriophages MS2 and phiX174 revealed different removal properties. MS2, which is widely used as a model organism to determine virus removal efficiencies of membranes, mostly showed a better removal than phiX174 for the natural water qualities tested. It seems that MS2 is possibly a less conservative surrogate for human enteric virus removal than phiX174. In bench-scale experiments log removal values (LRV) for MS2 of 2.5-6.0 and of 2.5-4.5 for phiX174 were obtained for the examined range of parameters. Phage removal obtained with differently fabricated semi-technical modules was quite variable for comparable parameter settings, indicating that module fabrication can lead to differing results. Potting temperature and module size were identified as influencing factors. In conclusion, careful attention has to be paid to the choice of experimental settings and module potting when using bench-scale or semi-technical scale experiments for UF membrane challenge tests.

The roles of bacteriophages in membrane-based water and wastewater treatment processes: A review

“…A few previous studies have shown an increase of bacteriophage retention with increasing organic contents in the feed water (Huang et al, 2012;Kreißel et al, 2012). The enhancement of bacteriophage removal was mainly attributed to (1) the accumulated fouling layers on the membranes due to rejected large-sized organics (similar to a 'dynamic membrane'), and (2) the greater pore constriction by the small organics that adhered to the membrane matrix.…”

“…Although all reported model bacteriophages have negatively-charged surfaces at neutral pH condition, their hydrophobic nature and isoelectric points are different (e.g., isoelectric point is 3.1 for MS2, 2.1 for GA, 2.7 for Qβ, and 2.1 for SP (Langlet et al, 2008); 3.8 to 5.5 for B-14 (Purnell et al, 2015)). The surface properties of bacteriophages determine their aggregation tendency, adsorption by natural organic compounds/sludge flocs, and interaction with membrane surfaces, which impact bacteriophage removal efficiency in natural waters and wastewaters (Boudaud et al, 2012;Chaudhry et al, 2015a;ElHadidy et al, 2013ElHadidy et al, , 2014Kreißel et al, 2012). For example, in natural waters, the bacteriophages with greater hydrophobicity are more efficiently rejected by membranes possibly due to their stronger interaction with natural organic substances and membrane surface (Boudaud et al, 2012;Kreißel et al, 2012).…”

“…The surface properties of bacteriophages determine their aggregation tendency, adsorption by natural organic compounds/sludge flocs, and interaction with membrane surfaces, which impact bacteriophage removal efficiency in natural waters and wastewaters (Boudaud et al, 2012;Chaudhry et al, 2015a;ElHadidy et al, 2013ElHadidy et al, , 2014Kreißel et al, 2012). For example, in natural waters, the bacteriophages with greater hydrophobicity are more efficiently rejected by membranes possibly due to their stronger interaction with natural organic substances and membrane surface (Boudaud et al, 2012;Kreißel et al, 2012). In contrast, in MBRs, bacteriophage removal efficiency was associated with the attachment capability of bacteriophages to activated sludge floc in certain cases, rather than electrostatic interactions with membranes (Chaudhry et al, 2015a).…”

“…It is worth noting that Antony et al (Antony et al, 2012) In these reported studies (Table 2), the bacteriophages such as MS2, F2, φX174, Qβ, GA, and F2, are the mostly-used model surrogates to simulate human enteric viruses in membranebased water and wastewater treatment processes. Although a few studies have compared virus removal efficiencies for various tested bacteriophages in the membrane processes (Boudaud et al, 2012;Chaudhry et al, 2015a;ElHadidy et al, 2013ElHadidy et al, , 2014Kreißel et al, 2012;Soussan et al, 2011), the findings are not similarly conclusive. For example, MS2 was removed more than φX174 in the experiments performed by Kreiβel et al (Kreißel et al, 2012) and ElHadidy et al (ElHadidy et al, 2013), but other researchers observed their comparable removal efficiencies (ElHadidy et al, 2014) or less removal for MS2 (Chaudhry et al, 2015b).…”

“…Although a few studies have compared virus removal efficiencies for various tested bacteriophages in the membrane processes (Boudaud et al, 2012;Chaudhry et al, 2015a;ElHadidy et al, 2013ElHadidy et al, , 2014Kreißel et al, 2012;Soussan et al, 2011), the findings are not similarly conclusive. For example, MS2 was removed more than φX174 in the experiments performed by Kreiβel et al (Kreißel et al, 2012) and ElHadidy et al (ElHadidy et al, 2013), but other researchers observed their comparable removal efficiencies (ElHadidy et al, 2014) or less removal for MS2 (Chaudhry et al, 2015b). This is attributed to the fact that the comparison of these surrogates was performed under completely non-identical experimental conditions.…”